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Sample records for bacteria influence microbial

  1. Microbial influenced corrosion by thermophilic bacteria

    Science.gov (United States)

    Lata, Suman; Sharma, Chhaya; Singh, Ajay

    2012-03-01

    The present study was undertaken to investigate microbial influenced corrosion (MIC) on stainless steels due to thermophilic bacteria Desulfotomaculum nigrificans. The objective of the study was to measure the extent of corrosion and correlate it with the growth of the biofilm by monitoring the composition of its extracellular polymeric substances (EPS). The toxic effect of heavy metals on MIC was also observed. For this purpose, stainless steels 304L, 316L and 2205 were subjected to electrochemical polarization and immersion tests in the modified Baar's media, control and inoculated, in anaerobic conditions at room temperature. Scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS) were used to identify the chemicals present in/outside the pit. The results show maximum corrosive conditions when bacterial activity is highest, which in turn minimizes the amount of carbohydrate and protein along with the increase in the fraction of uronic acid in carbohydrate in EPS of the biofilm. However, although bacterial activity and corrosion rate decreases, the amount of biofilm components continue to increase. It is also observed that the toxicity of metals ions affect the bacterial activity and EPS production. It was observed that Desulfotomaculum sp. has the ability to biodegrade its own EPS.

  2. Metabolic profiling of biofilm bacteria known to cause microbial influenced corrosion.

    Science.gov (United States)

    Beale, D J; Morrison, P D; Key, C; Palombo, E A

    2014-01-01

    This study builds upon previous research that demonstrated the simplicity of obtaining metabolite profiles of bacteria in urban water networks, by using the metabolic profile of bacteria extracted from a reticulation pipe biofilm, which is known to cause microbial influenced corrosion (MIC). The extracellular metabolites of the isolated bacteria, and those bacteria in consortium, were analysed in isolation, and after exposure to low levels of copper. Applying chemometric analytical methodologies to the metabolomic data, we were able to better understand the profile of the isolated biofilm bacteria, which were differentiated according to their activity and copper exposure. It was found that the metabolic activity of the isolated bacteria and the bacteria in consortium varied according to the bacterium's ability to metabolise copper. This demonstrates the power of metabolomic techniques for the discrimination of water reticulation biofilms comprising similar bacteria in consortium, but undergoing different physico-chemical activities, such as corrosion and corrosion inhibition. PMID:24434961

  3. Bacteria and microbially influenced corrosion in district heating systems. Prevention, control and supervision

    Energy Technology Data Exchange (ETDEWEB)

    Froelund, Bo [Teknologisk Inst., Miljoe (Denmark); Smidt, Henning D. [Teknologisk Inst., Energi (Denmark); Halkjaer Nielsen, Per [Aalborg Univ., Environmental Engineering Lab. (Denmark)

    1999-04-01

    Bacterial growth can be inhibited and microbially influenced corrosion can be prevented within the existing framework for water treatment at heating plants when the user is attentive. It is also possible to control microbial growth when it first has appeared with traditional controlling agents, and often in a lower concentration than usually recommended. These results have been achieved in the project called `Microbially influenced corrosion in district heating systems`. (au)

  4. The influence of different metal ions on light scattering properties of pattern microbial fuel cells' bacteria Desulfuromonas acetoxidans

    Science.gov (United States)

    Vasyliv, Oresta M.; Bilyy, Olexsandr I.; Getman, Vasyl'B.; Ferensovyich, Yaroslav P.; Yaremyk, Roman Y.; Hnatush, Svitlana O.

    2011-09-01

    Microbial fuel cell (MFC) technologies represent the newest approach for generating electricity - bioelectricity generation from biomass using bacteria. Desulfuromonas acetoxidans are aquatic obligatory anaerobic sulfur-reducing bacteria that possess an ability to produce electric current in the processes of organic matter oxidation and Fe3+- or Mn4+- reduction. These are pattern objects for MFC systems. They could be applied as a highly effective and self-sustaining model of wastewater treatment which contains energy in the form of biodegradable organic matter. But wastewaters contain high concentrations of xenobiotics, such as different heavy metals that have a detrimental effect towards all living organisms. The influence of different concentrations of MnCl2×4H2O, FeSO4 CuSO4, CdSO4, ZnSO4 and PbNO3 on light scattering properties of aquatic D. acetoxidans bacteria on the base of their cells' size distribution and relative content has been investigated by the new method of measurement. The cell distribution curve was in the range of 0.4 - 1.4 μm. The most crucial changes of cell concentration dependences, compared with other investigated metal ions, have been observed under the influence of copper ions. The ability of D. acetoxidans bacteria to produce electric current upon the specific cultivation conditions and the influence of Fe2+ and Mn2+ has been verified.

  5. Microbially influenced corrosion of stainless steels by aerobic bacteria; Kokisei saikin no kanyoshita sutenresu ko no biseibutsu fushoku

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, H.; Miyuki, H. [Sumitomo Metal Inductries Ltd., Osaka (Japan). Corporate Research and Development Lab.

    1996-03-20

    Influence of microorganisms on the corrosion of metals has been recognized since Kuhr proposed the hypothesis of corrosion promotion due to so called hydrogen double electrode when hydrogen formed in corrosion reaction of steel is used by anaerobic bacteria. Corrosion of metals caused by the influence of such type of microorganisms is known as Microbially influenced corrosion (MIC), and recently is paid attention specially in Europe and America. These recent years, research on MIC is showing active trend even in Japan. As for the research subjects of MIC, the example of corrosion promotion of carbon steel by sulfate reducing bacteria (SRB) in anaerobic environment is paid attention conventionally. Further, at present, effect of general type of aerobic heterotrophic bacteria on the corrosion of steel is paid attention and research is carried out actively. In this report, effect of aerobic heterotrophic bacteria on the corrosion of stainless steel is introduced focusing to the authors knowhow regarding the ennoblement phenomena of corrosion potential of stainless steel in natural sea water. 44 refs., 10 figs., 3 tabs.

  6. Environmentally-acquired bacteria influence microbial diversity and natural innate immune responses at gut surfaces

    Directory of Open Access Journals (Sweden)

    Pluske John R

    2009-11-01

    Full Text Available Abstract Background Early microbial colonization of the gut reduces the incidence of infectious, inflammatory and autoimmune diseases. Recent population studies reveal that childhood hygiene is a significant risk factor for development of inflammatory bowel disease, thereby reinforcing the hygiene hypothesis and the potential importance of microbial colonization during early life. The extent to which early-life environment impacts on microbial diversity of the adult gut and subsequent immune processes has not been comprehensively investigated thus far. We addressed this important question using the pig as a model to evaluate the impact of early-life environment on microbe/host gut interactions during development. Results Genetically-related piglets were housed in either indoor or outdoor environments or in experimental isolators. Analysis of over 3,000 16S rRNA sequences revealed major differences in mucosa-adherent microbial diversity in the ileum of adult pigs attributable to differences in early-life environment. Pigs housed in a natural outdoor environment showed a dominance of Firmicutes, in particular Lactobacillus, whereas animals housed in a hygienic indoor environment had reduced Lactobacillus and higher numbers of potentially pathogenic phylotypes. Our analysis revealed a strong negative correlation between the abundance of Firmicutes and pathogenic bacterial populations in the gut. These differences were exaggerated in animals housed in experimental isolators. Affymetrix microarray technology and Real-time Polymerase Chain Reaction revealed significant gut-specific gene responses also related to early-life environment. Significantly, indoor-housed pigs displayed increased expression of Type 1 interferon genes, Major Histocompatibility Complex class I and several chemokines. Gene Ontology and pathway analysis further confirmed these results. Conclusion Early-life environment significantly affects both microbial composition of the adult

  7. The influence of microbial factors on the susceptibility of bacteria to photocatalytic destruction

    OpenAIRE

    Robertson, Jeanette M. C.; Sieberg, Carina; Robertson, Peter K. J.

    2015-01-01

    The role that bacterial factors play in determining how bacteria respond to photocatalytic degradation is becoming increasingly recognised. Fimbriae which are thin, proteinaceous cell surface structures produced by many enterobacteria are generally considered to be important bacterial virulence determinants in the host. Recent studies, however, suggest that their expression may be increased during times of environmental stress to protect them against factors such as nutrient depletion and oxi...

  8. Interactions between fungi and bacteria influence microbial community structure in the Megachile rotundata larval gut.

    Science.gov (United States)

    McFrederick, Quinn S; Mueller, Ulrich G; James, Rosalind R

    2014-03-22

    Recent declines in bee populations coupled with advances in DNA-sequencing technology have sparked a renaissance in studies of bee-associated microbes. Megachile rotundata is an important field crop pollinator, but is stricken by chalkbrood, a disease caused by the fungus Ascosphaera aggregata. To test the hypothesis that some gut microbes directly or indirectly affect the growth of others, we applied four treatments to the pollen provisions of M. rotundata eggs and young larvae: antibacterials, antifungals, A. aggregata spores and a no-treatment control. We allowed the larvae to develop, and then used 454 pyrosequencing and quantitative PCR (for A. aggregata) to investigate fungal and bacterial communities in the larval gut. Antifungals lowered A. aggregata abundance but increased the diversity of surviving fungi. This suggests that A. aggregata inhibits the growth of other fungi in the gut through chemical or competitive interaction. Bacterial richness decreased under the antifungal treatment, suggesting that changes in the fungal community caused changes in the bacterial community. We found no evidence that bacteria affect fungal communities. Lactobacillus kunkeei clade bacteria were common members of the larval gut microbiota and exhibited antibiotic resistance. Further research is needed to determine the effect of gut microbes on M. rotundata health. PMID:24478297

  9. Monitoring Microbially Influenced Corrosion

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    Abstract Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria (SRB). The applicability and reliability of a number of corrosion monitoring techniques for monitoring MIC has been evaluated in experiments...... and diffusional effects and unreliable corrosion rates, when biofilm and ferrous sulphide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 by electrochemical techniques. Weight loss coupons and ER are recommended as necessary basic monitoring techniques....... EIS might be used for detection of MIC as the appearance of very large capacitances can be attributed to the combined ferrous sulphide and biofilm formation. Capacitance correlates directly with sulphide concentration in sterile sulphide media. Keywords: Corrosion monitoring, carbon steel, MIC, SRB...

  10. The Influence of Tallow on Rumen Metabolism, Microbial Biomass Synthesis and Fatty Acid Composition of Bacteria and Protozoa

    DEFF Research Database (Denmark)

    Weisbjerg, Martin Riis; Børsting, Christian Friis; Hvelplund, Torben

    1992-01-01

    Rumen metabolism, microbial biomass synthesis and microbial long chain fatty acid composition were studied in lactating cows fed at two levels of dry matter intake (L, 8.6 kg DM and H, 12.6 kg DM) with 0, 4 and 6% added tallow at the low feed level (L0, L4 and L6) and 0, 2, 4 and 6% at the high f...

  11. Critical parameters influencing microbial corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Ferris, F.G.

    1991-03-31

    The effects of injection water chemistry on the development of corrosive microbial biofilms, corrosion rates, and deposition of corrosion deposits was studied at an oil field water injection test facility in Alberta. Data were collected during two separate 12 week duration experimental runs. Attached bacterial populations were allowed to develop on removable steel sample coupons, and chemical treatment started after four weeks. Two different cocodiamine and bromonitropropane-diol based biocides were used in addition to a phosphate scale inhibitor. Of the various constituents present in the injection water, sulfate was noted as having a strong stimulative effect on sulfate reducing bacteria (SRB). Nitrate was inhibitory, whereas sulfide exhibited a positive correlation with SRB. While high concentrations of magnesium constrained SRB and organic acid producing bacteria (APB), high bacterial counts coincided with an apparent optimal range of 15 to 20 ppM total organic carbon. The results indicated that injection water chemistry strongly influences microbial growth and population distribution in water injection systems. Scanning electron microscopy indicated that complex pore geometries contribute to the meager permeability that constrains the penetration of biocides into biofilms. Most of the iron sulfide corrosion deposits consisted of an amorphous sulfur-deficient chlorine-rich phase, which sustains high corrosion rates when depolarized by hydrogen consuming SRB. 33 refs., 54 figs., 3 tabs.

  12. Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    2000-01-01

    Abstract Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria, e.g. on pipelines buried in soil and on marine structures. MIC of c...

  13. The biocathode of microbial electrochemical systems and microbially-influenced corrosion.

    Science.gov (United States)

    Kim, Byung Hong; Lim, Swee Su; Daud, Wan Ramli Wan; Gadd, Geoffrey Michael; Chang, In Seop

    2015-08-01

    The cathode reaction is one of the most important limiting factors in bioelectrochemical systems even with precious metal catalysts. Since aerobic bacteria have a much higher affinity for oxygen than any known abiotic cathode catalysts, the performance of a microbial fuel cell can be improved through the use of electrochemically-active oxygen-reducing bacteria acting as the cathode catalyst. These consume electrons available from the electrode to reduce the electron acceptors present, probably conserving energy for growth. Anaerobic bacteria reduce protons to hydrogen in microbial electrolysis cells (MECs). These aerobic and anaerobic bacterial activities resemble those catalyzing microbially-influenced corrosion (MIC). Sulfate-reducing bacteria and homoacetogens have been identified in MEC biocathodes. For sustainable operation, microbes in a biocathode should conserve energy during such electron-consuming reactions probably by similar mechanisms as those occurring in MIC. A novel hypothesis is proposed here which explains how energy can be conserved by microbes in MEC biocathodes. PMID:25976915

  14. COMPETITION BETWEEN ANOXYGENIC PHOTOTROPHIC BACTERIA AND COLORLESS SULFUR BACTERIA IN A MICROBIAL MAT

    NARCIS (Netherlands)

    VISSCHER, PT; VANDENENDE, FP; SCHAUB, BEM; VANGEMERDEN, H

    1992-01-01

    The populations of chemolithoautotrophic (colorless) sulfur bacteria and anoxygenic phototrophic bacteria were enumerated in a marine microbial mat. The highest population densities were found in the 0-5 mm layer of the mat: 2.0 X 10(9) cells CM-3 sediment, and 4.0 X 10(7) cells cm-3 sediment for th

  15. Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    2000-01-01

    Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria, e.g. on pipelines buried in soil and on marine structures. MIC of carbon steel must be monitored on-line in order to provide an efficient protection...

  16. Microbial Cellulose Production from Bacteria Isolated from Rotten Fruit

    OpenAIRE

    Rangaswamy, B.E.; Vanitha, K. P.; Hungund, Basavaraj S.

    2015-01-01

    Microbial cellulose, an exopolysaccharide produced by bacteria, has unique structural and mechanical properties and is highly pure compared to plant cellulose. Present study represents isolation, identification, and screening of cellulose producing bacteria and further process optimization. Isolation of thirty cellulose producers was carried out from natural sources like rotten fruits and rotten vegetables. The bacterial isolates obtained from rotten pomegranate, rotten sweet potato, and rott...

  17. Microbially influenced degradation of concrete structures

    Science.gov (United States)

    Rogers, Robert D.; Hamilton, Melinda A.; Nelson, Lee O.

    1998-03-01

    Steel reinforced concrete is the most widely used construction material in the world. The economic costs of repair or replacement of environmentally damaged concrete structures is astronomical. For example, half of the concrete bridges in the Federal Department of Transportation highway system are in need of major repairs. Microbially influenced degradation of concrete (MID) is one of the recognized degradative processes known to adversely affect concrete integrity. It is not possible to assign a specific percent of effect to any of these processes. However, MID has been shown to be as aggressive as any of the physical/chemical phenomena. In addition, the possibility exists that there is a synergism which results in cumulative effects from all the processes. Three groups of bacteria are known to promote MID. Of these, sulfur-oxidizing bacteria (SOB) are the most aggressive. Much is known about the nutritional needs of these bacteria. However, there has not been a biological linkage established between the presence of environmental, polluting sulfur sources and the degradation of concrete structures. It has been shown that the environmental pollutants sulfur dioxide and sulfite can be utilized by active SOB for the biological production of sulfuric acid. Therefore, it is not a reach of reality to assume that SOB exposed to these pollutants could have a major impact on the degradation of concrete structures. But, until the environment sulfur loop is closed it will not be possible to calculate how important SOB activity is in initiating and promoting damage.

  18. Microbially influenced corrosion of carbon steels

    Energy Technology Data Exchange (ETDEWEB)

    White, D.C.; Jack, R.F.; Dowling, N.J.E.; Franklin, M.J.; Nivens, D.E.; Brooks, S.; Mittelman, M.W.; Vass, A.A. (Tennessee Univ., Knoxville, TN (USA). Inst. for Applied Microbiology); Isaacs, H.S. (Brookhaven National Lab., Upton, NY (USA))

    1990-01-01

    Microbially influenced corrosion of pipeline steels is an economically important problem. Microbes form tubercles which block fluid flow and can facilitate localized corrosion leading to through-wall penetrations. Microbes of diverse physiological types and metabolic potentialities have been recovered from fresh tubercles or under-deposit corrosion and have been characterized. In tests utilizing sterilizable flow-through systems containing pipeline steel coupons, corrosion rates determined by nondestructive electrochemical means have indicated that increasing the number of physiological types of microbes inoculated into the system generally increased the severity of the microbially influenced corrosion (MIC). This study reports the MIC of monocultures and combinations of monocultures in an aerobic fresh water system with low sulfate and an anaerobic saline system. In both the aerobic and anaerobic systems, the combination of microbes induced greater MIC responses than the monocultures. In tests involving a combination of microbes in both systems in which one member was a sulfate-reducing bacteria (SRB), the corrosion mechanism was different for the control and the monocultures. This difference was indicated by the phase shift in the electrochemical impedance spectra (EIS). The localization of corrosion, that in many cases is the hallmark of MIC, may be initiated by the inhomogeneities of supposedly smooth metal surfaces. The scanning vibrating electrode technique (SVET) demonstrated non-uniform current densities over carbon steel electrodes polished to a 600 grit finish suggesting pitting and repassivation of pits in sterile medium.

  19. Nitrification and Nitrifying Bacteria in a Coastal Microbial Mat

    NARCIS (Netherlands)

    Fan, H.; Bolhuis, H.; Stal, L.J.

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tida

  20. Exoelectrogenic bacteria that power microbial fuel cells

    KAUST Repository

    Logan, Bruce E.

    2009-03-30

    There has been an increase in recent years in the number of reports of microorganisms that can generate electrical current in microbial fuel cells. Although many new strains have been identified, few strains individually produce power densities as high as strains from mixed communities. Enriched anodic biofilms have generated power densities as high as 6.9 W per m2 (projected anode area), and therefore are approaching theoretical limits. To understand bacterial versatility in mechanisms used for current generation, this Progress article explores the underlying reasons for exocellular electron transfer, including cellular respiration and possible cell-cell communication.

  1. Nitrification and Nitrifying Bacteria in a Coastal Microbial Mat

    OpenAIRE

    Fan, Haoxin; Bolhuis, Henk; Stal, Lucas J.

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is presen...

  2. NITRIFICATION AND NITRIFYING BACTERIA IN A COASTAL MICROBIAL MAT

    OpenAIRE

    Haoxin eFan; Henk eBolhuis; Lucas eStal

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is presen...

  3. The role of acetogens in microbially influenced corrosion of steel

    OpenAIRE

    Jaspreet eMand; Hyung Soo ePark; Jack, Thomas R.; Gerrit eVoordouw

    2014-01-01

    Microbially influenced corrosion (MIC) of iron (Fe0) by sulfate-reducing bacteria (SRB) has been studied extensively. Through a mechanism, that is still poorly understood, electrons or hydrogen (H2) molecules are removed from the metal surface and used as electron donor for sulfate reduction. The resulting ferrous ions precipitate in part with the sulfide produced, forming characteristic black iron sulfide. Hydrogenotrophic methanogens can also contribute to MIC. Incubation of pipeline water ...

  4. Electric current generation by sulfur-reducing bacteria in microbial-anode fuel cell

    Science.gov (United States)

    Vasyliv, Oresta M.; Bilyy, Oleksandr I.; Ferensovych, Yaroslav P.; Hnatush, Svitlana O.

    2012-10-01

    Sulfur - reducing bacteria are a part of normal microflora of natural environment. Their main function is supporting of reductive stage of sulfur cycle by hydrogen sulfide production in the process of dissimilative sulfur-reduction. At the same time these bacteria completely oxidize organic compounds with CO2 and H2O formation. It was shown that they are able to generate electric current in the two chamber microbial-anode fuel cell (MAFC) by interaction between these two processes. Microbial-anode fuel cell on the basis of sulfur- and ferric iron-reducing Desulfuromonas acetoxidans bacteria has been constructed. It has been shown that the amount of electricity generation by investigated bacteria is influenced by the concentrations of carbon source (lactate) and ferric iron chloride. The maximal obtained electric current and potential difference between electrodes equaled respectively 0.28-0.29 mA and 0.19-0.2 V per 0.3 l of bacterial suspension with 0.4 g/l of initial biomass that was grown under the influence of 0.45 mM of FeCl3 and 3 g/l of sodium lactate as primal carbon source. It has also been shown that these bacteria are resistant to different concentrations of silver ions.

  5. Microbial Cellulose Production from Bacteria Isolated from Rotten Fruit

    Directory of Open Access Journals (Sweden)

    B. E. Rangaswamy

    2015-01-01

    Full Text Available Microbial cellulose, an exopolysaccharide produced by bacteria, has unique structural and mechanical properties and is highly pure compared to plant cellulose. Present study represents isolation, identification, and screening of cellulose producing bacteria and further process optimization. Isolation of thirty cellulose producers was carried out from natural sources like rotten fruits and rotten vegetables. The bacterial isolates obtained from rotten pomegranate, rotten sweet potato, and rotten potato were identified as Gluconacetobacter sp. RV28, Enterobacter sp. RV11, and Pseudomonas sp. RV14 through morphological and biochemical analysis. Optimization studies were conducted for process parameters like inoculum density, temperature, pH, agitation, and carbon and nitrogen sources using Gluconacetobacter sp. RV28. The strain produced 4.7 g/L of cellulose at optimum growth conditions of temperature (30°C, pH (6.0, sucrose (2%, peptone (0.5%, and inoculum density (5%. Characterization of microbial cellulose was done by scanning electron microscopy (SEM.

  6. Microbially Influenced Corrosion of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Deuk; Ryu, Seung Ki; Kim Young Ho [POSCO Techanical Researh Laboratories, Pohang (Korea, Republic of)

    1996-06-25

    Microbially Influenced Corrosion(MIC) is often a significant factor in controlling the long-term performance of most structural materials in industrial applications. This papers cover MIC mechanism and evaluation of stainless steels in soil and sea water environments. Papers also cover detection, monitoring and mitigation of MIC, biocides and treatments. (author). 28 refs., 2 tabs., 5 figs.

  7. Nitrification and Nitrifying Bacteria in a Coastal Microbial Mat

    Science.gov (United States)

    Fan, Haoxin; Bolhuis, Henk; Stal, Lucas J.

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is present in both AOA and AOB, were assessed and the potential nitrification rates in these mats were measured. The potential nitrification rates in the three mat types were highest in autumn and lowest in summer. AOB and AOA amoA genes were present in all three mat types. The composition of the AOA and AOB communities in the mats of the tidal and intertidal stations, based on the diversity of amoA, were similar and clustered separately from the supratidal microbial mat. In all three mats AOB amoA genes were significantly more abundant than AOA amoA genes. The abundance of neither AOB nor AOA amoA genes correlated with the potential nitrification rates, but AOB amoA transcripts were positively correlated with the potential nitrification rate. The composition and abundance of amoA genes seemed to be partly driven by salinity, ammonium, temperature, and the nitrate/nitrite concentration. We conclude that AOB are responsible for the bulk of the ammonium oxidation in these coastal microbial mats. PMID:26648931

  8. NITRIFICATION AND NITRIFYING BACTERIA IN A COASTAL MICROBIAL MAT

    Directory of Open Access Journals (Sweden)

    Haoxin eFan

    2015-12-01

    Full Text Available The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA or ammonium-oxidizing bacteria (AOB. We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is present in both AOA and AOB, were assessed and the potential nitrification rates in these mats were measured. The potential nitrification rates in the three mat types were highest in autumn and lowest in summer. AOB and AOA amoA genes were present in all three mat types. The composition of the AOA and AOB communities in the mats of the tidal and intertidal stations, based on the diversity of amoA, were similar and clustered separately from the supratidal microbial mat. In all three mats AOB amoA genes were significantly more abundant than AOA amoA genes. The abundance of neither AOB nor AOA amoA genes correlated with the potential nitrification rates, but AOB amoA transcripts were positively correlated with the potential nitrification rate. The composition and abundance of amoA genes seemed to be partly driven by salinity, ammonium, temperature and the nitrate/nitrite concentration. We conclude that AOB are responsible for the bulk of the ammonium oxidation in these coastal microbial mats.

  9. Nitrification and Nitrifying Bacteria in a Coastal Microbial Mat.

    Science.gov (United States)

    Fan, Haoxin; Bolhuis, Henk; Stal, Lucas J

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is present in both AOA and AOB, were assessed and the potential nitrification rates in these mats were measured. The potential nitrification rates in the three mat types were highest in autumn and lowest in summer. AOB and AOA amoA genes were present in all three mat types. The composition of the AOA and AOB communities in the mats of the tidal and intertidal stations, based on the diversity of amoA, were similar and clustered separately from the supratidal microbial mat. In all three mats AOB amoA genes were significantly more abundant than AOA amoA genes. The abundance of neither AOB nor AOA amoA genes correlated with the potential nitrification rates, but AOB amoA transcripts were positively correlated with the potential nitrification rate. The composition and abundance of amoA genes seemed to be partly driven by salinity, ammonium, temperature, and the nitrate/nitrite concentration. We conclude that AOB are responsible for the bulk of the ammonium oxidation in these coastal microbial mats. PMID:26648931

  10. Study on microbial influence assessment in geological disposal

    International Nuclear Information System (INIS)

    We conducted the following four investigations concerned with microbial influence in geological disposal facilities. (1) Improvement of the FEP dictionary and investigation on chemical evolution of nitrate by microbes. (2) Experimental estimation of microbial mobility in compacted Na bentonite saturated by synthetic seawater with 30wt% silica sand and Ca bentonite with 30wt % silica sand. (Both dry densities are 1.6 g/cm3). (3) Habitation of microbes in Na rich bentonite deposit and Ca rich one. (4) Interaction between SRB (sulfate reducing bacteria) and Np in a reducing environment at Eh = -85mV. As the result, it was revealed that (1) microbial activity in near field rock and microbial denitrification of nitrate under the existence of electron donor are important, (2) microbes didn't move in Na bentonite in 3 weeks and moved to the distance of 20 mm in Ca bentonite, and (3) microorganisms existed at the inside of the deposits. (4) The difference between distribution coefficient of Eh = -85mV and Eh = -500mV was evaluated. (author)

  11. Bacteria and microbial induced corrosion in district heating systems; Bakterier og mikrobiel betinget korrosion i fjernvarmesystemer

    Energy Technology Data Exchange (ETDEWEB)

    Froelund, B. [Dansk Teknologisk Inst., Miljoeteknik, Aarhus (Denmark); Smidt, H.D. [Dansk Teknologisk Inst., Energi, Aarhus (Denmark); Halkjaer Nielsen, P. [Aalborg Univ., Lab. for Miljoeteknik (Denmark)

    1998-09-01

    Bacteria has been found in district heating systems in a number that indicate the risk of technical problems of a microbial nature. Bacteria in district heating systems can cause problems like unpleasant smell, increased roughness on the inner side of the pipes, decreased performance of the heat exchangers etc. There is also found bio film containing bacteria on the surface of the pipes. In the bio film there are often other conditions than in water, e.g. a lower pH value that improves growth of bacteria. Finally there is found sulphate-reducing bacteria. These bacteria can cause corrosion; a corrosion form called microbial induced corrosion. The report gives recommendations on how to reduce these bacteria. The bacteria can be reduced by regulating the pH value or by minimising the organic material in the water and finally by biocides that are able to kill the microorganisms. (SM) EFP-95. 12 refs.

  12. Counting viruses and bacteria in photosynthetic microbial mats

    NARCIS (Netherlands)

    C. Carreira; M. Staal; M. Middelboe; C.P.D. Brussaard

    2015-01-01

    Viral abundances in benthic environments are the highest found in aquatic systems. Photosynthetic microbial mats represent benthic environments with high microbial activity and possibly high viral densities, yet viral abundances have not been examined in such systems. Existing extraction procedures

  13. Microbially-influenced corrosion capability of Yucca Mountain bacterial isolates

    Energy Technology Data Exchange (ETDEWEB)

    Pitonzo, B.; Castro, P.; Amy, P. [Univ. of Nevada, Las Vegas, NV (United States)] [and others

    1996-12-01

    Microorganisms implicated in microbially-influenced corrosion have been isolated from the deep subsurface at Yucca Mt. Iron-oxidizing (FeOx), sulfate-reducing (SRB), and exopolymer (EPS)-producing bacteria were found. Microbial corrosion rate was monitored electrochemically. The test system was composed of a 1020 carbon steel coupon immersed in soft R2A agar prepared with simulated groundwater (J-13). A KCl bridge was used to connect the test and reference cell (calomel electrode). A platinum counter-electrode was used to apply a potential to the coupon and the corrosion process was measured by a potentiostat (Gamry). Corrosion cells (3x) were inoculated with purified cultures of EPS-producing bacteria and enrichment cultures of FeOx and SRB bacteria. Test cells were inoculated with microorganisms separately, as well as in various combinations. An uninoculated control cell was prepared to assess abiotic corrosion. Average corrosion rates were measured in milli-inches per year (mpy) against time. The control, and cells containing EPS-producing, FeOx or SRB bacteria alone or in combination demonstrated a rapid decrease in corrosion rate by 3 days. The corrosion rates stabilized, and at 35 days peaked at 2.25 mpy (FeOx), 3.30 mpy (SRB), and 2.80 mpy (EPS). AU of these values were significantly higher than the corrosion rate observed in the control cell, 1.30 mpy at 35 days. The various combinations demonstrated higher corrosion rates than any bacterial group alone. Coupons were cleaned, revealing surface pits. 200 pits/sq. in. were counted on a coupon previously exposed to a mixture of EPS-producing and FeOx microorganisms. Pit diameter ranged from 0.25 to 2.75 mm. The results indicate that Yucca Mountain microorganisms, alone and in combination, are capable of causing corrosion of 1020 carbon steel.

  14. Fermentation couples Chloroflexi and sulfate-reducing bacteria to Cyanobacteria in hypersaline microbial mats

    OpenAIRE

    Lee, Jackson Z.; Burow, Luke C; Dagmar eWoebken; R Craig Everroad; Kubo, Michael D.; Alfred Michael Spormann; Weber, Peter K.; Jennifer ePett-Ridge; Bebout, Brad M; Hoehler, Tori M.

    2014-01-01

    Past studies of hydrogen cycling in hypersaline microbial mats have shown an active nighttime cycle, with production largely from Cyanobacteria and consumption from sulfate-reducing bacteria (SRB). However, the mechanisms and magnitude of hydrogen cycling have not been extensively studied. Two mats types near Guerrero Negro, Mexico -- permanently submerged Microcoleus microbial mats (GN-S), and intertidal Lyngbya microbial mats (GN-I) -- were used in microcosm diel manipulation experiments wi...

  15. Microbial-influenced cement degradation: Literature review

    International Nuclear Information System (INIS)

    The Nuclear Regulatory Commission stipulates that disposed low-level radioactive waste (LLW) be stabilized. Because of apparent ease of use and normal structural integrity, cement has been widely used as a binder to solidify LLW. However, the resulting waste forms are sometimes susceptible to failure due to the actions of waste constituents, stress, and environment. This report reviews literature which addresses the effect of microbiologically influenced chemical attack on cement-solidified LLW. Groups of microorganisms are identified, which are capable of metabolically converting organic and inorganic substrates into organic and mineral acids. Such acids aggressively react with concrete and can ultimately lead to structural failure. Mechanisms inherent in microbial-influenced degradation of cement-based material are the focus of this report. This report provides sufficient evidence of the potential for microbial-influenced deterioration of cement-solidified LLW to justify the enumeration of the conditions necessary to support the microbiological growth and population expansion, as well as the development of appropriate tests necessary to determine the resistance of cement-solidified LLW to microbiological-induced degradation that could impact the stability of the waste form

  16. MATHEMATICAL SIMULATION OF THE INTERACTIONS AMONG CYANOBACTERIA, PURPLE SULFUR BACTERIA AND CHEMOTROPIC SULFUR BACTERIA IN MICROBIAL MAT COMMUNITIES

    NARCIS (Netherlands)

    DEWIT, R; VANDENENDE, FP; VANGEMERDEN, H

    1995-01-01

    A deterministic one-dimensional reaction diffusion model was constructed to simulate benthic stratification patterns and population dynamics of cyanobacteria, purple and colorless sulfur bacteria as found in marine microbial mats. The model involves the major biogeochemical processes of the sulfur c

  17. Fate of 14C-labeled microbial products derived from nitrifying bacteria in autotrophic nitrifying biofilms

    OpenAIRE

    Okabe, Satoshi; Kindaichi, Tomonori; Ito, Tsukasa

    2005-01-01

    The cross-feeding of microbial products derived from 14C-labeled nitrifying bacteria to heterotrophic bacteria coexisting in an autotrophic nitrifying biofilm was quantitatively analyzed by using microautoradiography combined with fluorescence in situ hybridization (MAR-FISH). After only nitrifying bacteria were labeled with [14C] bicarbonate, biofilm samples were incubated with and without NH4+ as a sole energy source for 10 days. The transfer of 14C originally incorporated into nitrifying b...

  18. Fate of 14C-Labeled Microbial Products Derived from Nitrifying Bacteria in Autotrophic Nitrifying Biofilms

    OpenAIRE

    Okabe, Satoshi; Kindaichi, Tomonori; Ito, Tsukasa

    2005-01-01

    The cross-feeding of microbial products derived from 14C-labeled nitrifying bacteria to heterotrophic bacteria coexisting in an autotrophic nitrifying biofilm was quantitatively analyzed by using microautoradiography combined with fluorescence in situ hybridization (MAR-FISH). After only nitrifying bacteria were labeled with [14C] bicarbonate, biofilm samples were incubated with and without NH4+ as a sole energy source for 10 days. The transfer of 14C originally incorporated into nitrifying b...

  19. Microbially influenced corrosion of stainless steels in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, U.P.; Wolfram, J.H.; Rogers, R.D.

    1990-01-01

    This paper reviews the components, causative agents, corrosion sites, and potential failure modes of stainless steel components susceptible to microbially influenced corrosion (MIC). The stainless steel components susceptible to MIC are located in the reactor coolant, emergency, and reactor auxiliary systems, and in many plants, in the feedwater train and condenser. The authors assessed the areas of most high occurrence of corrosion and found the sites most susceptible to MIC to the heat-affected zones in the weldments of sensitized stainless steel. Pitting is the predominant MIC corrosion mechanisms, caused by sulfur reducing bacteria (SRB). Also discussed is the current status of the diagnostic, preventive, and mitigation techniques, including use of improved water chemistry, alternate materials, and improved thermomechanical treatments. 37 refs., 3 figs.

  20. Fourier transform-infrared spectroscopic methods for microbial ecology: analysis of bacteria, bacteria-polymer mixtures and biofilms

    Science.gov (United States)

    Nichols, P. D.; Henson, J. M.; Guckert, J. B.; Nivens, D. E.; White, D. C.

    1985-01-01

    Fourier transform-infrared (FT-IR) spectroscopy has been used to rapidly and nondestructively analyze bacteria, bacteria-polymer mixtures, digester samples and microbial biofilms. Diffuse reflectance FT-IR (DRIFT) analysis of freeze-dried, powdered samples offered a means of obtaining structural information. The bacteria examined were divided into two groups. The first group was characterized by a dominant amide I band and the second group of organisms displayed an additional strong carbonyl stretch at approximately 1740 cm-1. The differences illustrated by the subtraction spectra obtained for microbes of the two groups suggest that FT-IR spectroscopy can be utilized to recognize differences in microbial community structure. Calculation of specific band ratios has enabled the composition of bacteria and extracellular or intracellular storage product polymer mixtures to be determined for bacteria-gum arabic (amide I/carbohydrate C-O approximately 1150 cm-1) and bacteria-poly-beta-hydroxybutyrate (amide I/carbonyl approximately 1740 cm-1). The key band ratios correlate with the compositions of the material and provide useful information for the application of FT-IR spectroscopy to environmental biofilm samples and for distinguishing bacteria grown under differing nutrient conditions. DRIFT spectra have been obtained for biofilms produced by Vibrio natriegens on stainless steel disks. Between 48 and 144 h, an increase in bands at approximately 1440 and 1090 cm-1 was seen in FT-IR spectra of the V. natriegens biofilm. DRIFT spectra of mixed culture effluents of anaerobic digesters show differences induced by shifts in input feedstocks. The use of flow-through attenuated total reflectance has permitted in situ real-time changes in biofilm formation to be monitored and provides a powerful tool for understanding the interactions within adherent microbial consortia.

  1. Influence of Engineering Bacteria Quantitative Inspection on Diversity of Anpeng Alkali Mine Resources Exploitation

    Directory of Open Access Journals (Sweden)

    Yu Tao

    2016-03-01

    Full Text Available Cadmium (Cd is a heavy metal pollutant seriously threatening creatures, and highly concentrated Cd in soil severely inhibits the activity of microbial populations. Soil in Anpeng Alkali Mine area in Nanyang city (Henan province is seriously polluted by heavy metal. Both copper (Cu and Cd content are found to be over standard, in which, Cu belongs to mild contamination while Cd is a serious contamination. To detect diversity of microbial communities in soil in the process of bioremediation, Cd polluted soil samples are collected from orefield for pot experiment, Biolog micro-plate technology is used to study the influence of applying low, medium and high amount of rice straw (5.3 t/ha, 10.2 t/ha and 23.4 t/ha in polluted soil and combining low, medium and high amount of rice straw with surface displayed engineering bacteria (X4/pCIM on microbial community. In the meantime, X4/pCIM is quantitatively measured by real-time polymerase chain reaction (PCR. Biolog experimental results indicate that the combination of rice straw and engineering bacteria is able to change the composition of soil microbial community, and has a difference in influencing rhizosphere and non-rhizosphere microorganisms. Through real-time PCR, it is found that the number of engineering bacteria falls to 103 after 120 days of bioremediation. Therefore, it can be concluded that combining rice straw with engineering bacteria can change the composition of soil microbial community and have diverse influences as application rate changes, without obvious rules to follow.

  2. [Distribution and influence factors of Anammox bacteria in sewage treatment systems].

    Science.gov (United States)

    Zheng, Bingyu; Peng, Yongzhen; Zhang, Liang; Yang, Anming; Zhang, Shujun

    2014-12-01

    Nitrogen removal techniques based on Anammox process are developing rapidly these years. The distribution and diversity of Anammox have become important research directions. A variety of Anammox have been detected till now, of which only Kuenenia and Brocadia are often detected in wastewater treatment systems. In addition, in a single niche there is only one type of Anammox bacteria. However, the distribution mechanism and transformation of Anammox bacteria in different niches are still ambiguous. Therefore, the distribution of Anammox in various conditions was summarized and analyzed in this article. And the key factors influencing the distribution of Anammox were concluded, including substrate concentration and the specific growth rate, sludge properties and microbial niche, the joint action and influence of multiple factors. The engineering significance research on the distribution and influencing factors of Anammox bacteria in the sewage system and proposed research prospects were expounded. PMID:26016371

  3. Microbial ecology of halo-alkaliphilic sulfur bacteria

    NARCIS (Netherlands)

    Foti, M.J.

    2007-01-01

    The research of this thesis focussed on the investigation of the microbial diversity in soda lakes, giving a special attention to the micro-organisms involved in the sulphur cycle. The present PhD was part of a bigger project aiming to develop a biological process for the removal of hydrogen sulphid

  4. Mineral Influence on Microbial Survival During Carbon Sequestration

    Science.gov (United States)

    Santillan, E. U.; Shanahan, T. M.; Wolfe, W. W.; Bennett, P.

    2012-12-01

    CO2 sequestered in a deep saline aquifer will perturb subsurface biogeochemistry by acidifying the groundwater and accelerating mineral diagenesis. Subsurface microbial communities heavily influence geochemistry through their metabolic processes, such as with dissimilatory iron reducing bacteria (DIRB). However, CO2 also acts as a sterilant and will perturb these communities. We investigated the role of mineralogy and its effect on the survival of microbes at high PCO2 conditions using the model DIRB Shewanella oneidensis MR-1. Batch cultures of Shewanella were grown to stationary phase and exposed to high PCO2 using modified Parr reactors. Cell viability was then determined by plating cultures after exposure. Results indicate that at low PCO2 (2 bar), growth and iron reduction are decreased and cell death occurs within 1 hour when exposed to CO2 pressures of 10 bar or greater. Further, fatty acid analysis indicates microbial lipid degradation with C18 fatty acids being the slowest lipids to degrade. When cultures were grown in the presence of rocks or minerals representative of the deep subsurface such as carbonates and silicates and exposed to 25 bar CO2, survival lasted beyond 2 hours. The most effective protecting substratum was quartz sandstone, with cultures surviving beyond 8 hours of CO2 exposure. Scanning electron microscope images reveal biofilm formation on the mineral surfaces with copious amounts of extracellular polymeric substances (EPS) present. EPS from these biofilms acts as a reactive barrier to the CO2, slowing the penetration of CO2 into cells and resulting in increased survival. When biofilm cultures were grown with Al and As to simulate the release of toxic metals from minerals such as feldspars and clays, survival time decreased, indicating mineralogy may also enhance microbial death. Biofilms were then grown on iron-coated quartz sand to determine conversely what influence biofilms may have on mineral dissolution during CO2 perturbation

  5. DEVELOPMENT OF RESISTANCE IN BACTERIA AGAINST ANTI - MICROBIAL AGENTS: REASONS, THREATS AND ONGOING ENCOUNTER

    Directory of Open Access Journals (Sweden)

    Shibabrata Pattanayak

    2011-07-01

    Full Text Available Development of Multi Druug Resistant bacteria is creating a very severe problem in anti-microbial chemotherapy. Many recently developed antibiotics are found incapable to control resistant organisms.The reasons of development of resistance gene in the bacterial plasmid and their quick spread among various related and unrelated bacteria are analysed in this article along with discussion of world wide ongoing research to combat the problem.

  6. Survey of microbial oxygenases: trichloroethylene degradation by propane-oxidizing bacteria.

    OpenAIRE

    Wackett, L P; Brusseau, G A; Householder, S R; Hanson, R S

    1989-01-01

    Microorganisms that biosynthesize broad-specificity oxygenases to initiate metabolism of linear and branched-chain alkanes, nitroalkanes, cyclic ketones, alkenoic acids, and chromenes were surveyed for the ability to biodegrade trichloroethylene (TCE). The results indicated that TCE oxidation is not a common property of broad-specificity microbial oxygenases. Bacteria that contained nitropropane dioxygenase, cyclohexanone monooxygenase, cytochrome P-450 monooxygenases, 4-methoxybenzoate monoo...

  7. Decay of Fecal Indicator Bacteria and Microbial Source Tracking Markers in Cattle Feces

    Science.gov (United States)

    The survival of fecal indicator bacteria (FIB) and microbial source tracking (MST) markers in water microcosms and manure amended soils has been well documented; however, little is known about the survival of MST markers in bovine feces deposited on pastures. We conducted a study...

  8. Perchlorate reduction by hydrogen autotrophic bacteria and microbial community analysis using high-throughput sequencing.

    Science.gov (United States)

    Wan, Dongjin; Liu, Yongde; Niu, Zhenhua; Xiao, Shuhu; Li, Daorong

    2016-02-01

    Hydrogen autotrophic reduction of perchlorate have advantages of high removal efficiency and harmless to drinking water. But so far the reported information about the microbial community structure was comparatively limited, changes in the biodiversity and the dominant bacteria during acclimation process required detailed study. In this study, perchlorate-reducing hydrogen autotrophic bacteria were acclimated by hydrogen aeration from activated sludge. For the first time, high-throughput sequencing was applied to analyze changes in biodiversity and the dominant bacteria during acclimation process. The Michaelis-Menten model described the perchlorate reduction kinetics well. Model parameters q(max) and K(s) were 2.521-3.245 (mg ClO4(-)/gVSS h) and 5.44-8.23 (mg/l), respectively. Microbial perchlorate reduction occurred across at pH range 5.0-11.0; removal was highest at pH 9.0. The enriched mixed bacteria could use perchlorate, nitrate and sulfate as electron accepter, and the sequence of preference was: NO3(-) > ClO4(-) > SO4(2-). Compared to the feed culture, biodiversity decreased greatly during acclimation process, the microbial community structure gradually stabilized after 9 acclimation cycles. The Thauera genus related to Rhodocyclales was the dominated perchlorate reducing bacteria (PRB) in the mixed culture.

  9. Interactions of bacteria with diatoms: Influence on natural marine biofilms.

    Digital Repository Service at National Institute of Oceanography (India)

    Khandeparker, L.; DeCosta, P.M.; Anil, A.C.; Sawant, S.S.

    influenced by monsoons: spatial and temporal variations. Marine Biology, 148, 693-709. Mitbavkar S., Anil A.C. (2007) Species interactions within a fouling diatom community: roles of nutrients, initial inoculum and competitive strategies. Biofouling, 23, 99... by bacteria that helps in competition and signaling processes. The changes in fouling diatom communities when treated with antibiotics indicate the relevance of bacteria in influencing the biofilm. Streptomycin and chloramphenicol (produced naturally...

  10. Controlling microbially influenced corrosion through piping geometry

    Energy Technology Data Exchange (ETDEWEB)

    Angell, P.; Schefski, C. [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada); Richard, R.; Mills, G.; Pestonji, S. [Pickering Nuclear Generating Station, Ontario Power Generation, Pickering, Ontario (Canada)

    2004-07-01

    Power plants have experienced tuberculation and microbially influenced corrosion (MIC) in systems that use raw, or minimally treated, water. Piping geometry can have a significant effect on MIC. A geometry that allows the action of thermal convection to provide constant low levels of oxygen, under near static flow conditions, are known to promote tuberculation and MIC. The two geometries studied in this paper are: Piping geometry with horizontal secondary headers between a flowing ring header and a vertical riser (pipestand) which is susceptible to MIC; and, piping geometry with vertical secondary headers between a flowing ring header and a vertical riser (pipestand) which is not susceptible to MIC. A trend of historical failures due to pinhole leaks has been noted in pipes that are routinely stagnant or have low flow, but are connected to pipes that see regular flow. Accurate predictions of problem areas were made from our understanding of the failure mechanism. Initially, inspections were completed to determine the extent of degradation in the PNGS fire protection system. Radiographic inspections and visual inspections indicated that sections of the secondary headers that had an immediate vertical take-off from the flowing ring header (as opposed to the typical horizontal take-off) appeared to exhibit a much lower rate of subsequent tuberculation. This paper will present historical station data to support the concept that piping geometry changes can significantly lower the risk of MIC. An explanation will be presented demonstrating how convective mixing is reduced with the vertical configuration, thus reducing the tuberculation and MIC. Similar geometry changes are expected to significantly lower the incidence of tuberculation and MIC in other systems that use raw water with similar flow patterns. (author)

  11. Influence of disturbances on bacteria level in an operating room

    DEFF Research Database (Denmark)

    Brohus, Henrik; Hyldig, Mikkel; Kamper, Simon;

    2008-01-01

    In operating rooms great effort is manifested to reduce the bacteria level in order to decrease the risk of infections. The main source of bacteria is the staff and the patient, thus, the resulting bacteria concentration is roughly speaking a combination of the ventilation system and the emission...... from the occupants. This study investigates the influence of two main disturbances in an operating room namely the door opening during the operation and the activity level of the staff. It is found that the frequent door opening in this case does not cause significant transport of air from outside...... the operating room to the wound area of the patient. However, a significant influence of the activity level on the bacteria emission and concentration is found. Counting the number of persons in an operating room to estimate the bacteria source strength is not sufficient, the corresponding activity level must...

  12. The role of acetogens in microbial influenced corrosion of steel

    Directory of Open Access Journals (Sweden)

    Jaspreet eMand

    2014-06-01

    Full Text Available Microbially-influenced corrosion (MIC of iron (Fe0 by sulfate reducing bacteria (SRB has been studied extensively. Through a mechanism, that is still poorly understood, electrons or hydrogen (H2 molecules are removed from the metal surface and used as electron donor for sulfate reduction. The resulting ferrous ions precipitate in part with the sulfide produced, forming characteristic black iron sulfide. Hydrogenotrophic methanogens can also contribute to MIC. Incubation of pipeline water samples, containing bicarbonate and some sulfate, in serum bottles with steel coupons and a headspace of 10% (vol/vol CO2 and 90% N2, indicated formation of acetate and methane. Incubation of these samples in serum bottles, containing medium with coupons and bicarbonate but no sulfate, also indicated that formation of acetate preceded the formation of methane. Microbial community analyses of these enrichments indicated the presence of Acetobacterium, as well we of hydrogenotrophic and acetotrophic methanogens. The formation of acetate by homoacetogens, such as Acetobacterium woodii from H2 (or Fe0 and CO2, is potentially important, because acetate is a required carbon source for many SRB growing with H2 and sulfate. A consortium of the SRB Desulfovibrio vulgaris Hildenborough and A. woodii was able to grow in defined medium with H2, CO2 and sulfate, because A. woodii provides the acetate, needed by D. vulgaris under these conditions. Likewise, general corrosion rates of metal coupons incubated with D. vulgaris in the presence of acetate or in the presence of A. woodii were higher than in the absence of acetate or A. woodii, respectively. An extended MIC model capturing these results is presented.

  13. The role of acetogens in microbially influenced corrosion of steel

    Science.gov (United States)

    Mand, Jaspreet; Park, Hyung Soo; Jack, Thomas R.; Voordouw, Gerrit

    2014-01-01

    Microbially influenced corrosion (MIC) of iron (Fe0) by sulfate-reducing bacteria (SRB) has been studied extensively. Through a mechanism, that is still poorly understood, electrons or hydrogen (H2) molecules are removed from the metal surface and used as electron donor for sulfate reduction. The resulting ferrous ions precipitate in part with the sulfide produced, forming characteristic black iron sulfide. Hydrogenotrophic methanogens can also contribute to MIC. Incubation of pipeline water samples, containing bicarbonate and some sulfate, in serum bottles with steel coupons and a headspace of 10% (vol/vol) CO2 and 90% N2, indicated formation of acetate and methane. Incubation of these samples in serum bottles, containing medium with coupons and bicarbonate but no sulfate, also indicated that formation of acetate preceded the formation of methane. Microbial community analyses of these enrichments indicated the presence of Acetobacterium, as well as of hydrogenotrophic and acetotrophic methanogens. The formation of acetate by homoacetogens, such as Acetobacterium woodii from H2 (or Fe0) and CO2, is potentially important, because acetate is a required carbon source for many SRB growing with H2 and sulfate. A consortium of the SRB Desulfovibrio vulgaris Hildenborough and A. woodii was able to grow in defined medium with H2, CO2, and sulfate, because A. woodii provides the acetate, needed by D. vulgaris under these conditions. Likewise, general corrosion rates of metal coupons incubated with D. vulgaris in the presence of acetate or in the presence of A. woodii were higher than in the absence of acetate or A. woodii, respectively. An extended MIC model capturing these results is presented. PMID:24917861

  14. [Anoxygenic phototrophic bacteria from microbial communities of Goryachinsk Thermal Spring (Baikal Area, Russia)].

    Science.gov (United States)

    Kalashnikov, A M; Gaĭsin, V A; Sukhacheva, M V; Namsaraeva, B B; Panteleeva, A N; Nuianzina-Boldareva, E N; Kuznetsov, B B; Gorlenko, V M

    2014-01-01

    Species composition of anoxygenic phototrophic bacteria in microbial mats of the Goryachinsk thermal spring was investigated along the temperature gradient. The spring belonging to nitrogenous alkaline hydrotherms is located at the shore of Lake Baikal 188 km north-east from Ulan-Ude. The water is of the sulfate-sodium type, contains trace amounts of sulfide, salinity does not exceed 0.64 g/L, pH 9.5. The temperature at the outlet of the spring may reach 54 degrees C. The cultures of filamentous anoxygenic phototrophic bacteria, nonsulfur and sulfur purple bacteria, and aerobic anoxygenic phototrophic bacteria were identified using the pufLM molecular marker. The fmoA marker was used for identification of green sulfur bacteria. Filamentous cyanobacteria predominated in the mats, with anoxygenic phototrophs comprising a minor component of the phototrophic communities. Thermophilic bacteria Chloroflexus aurantiacus were detected irn the samples from both the thermophilic and mesophilic mats. Cultures ofnonsulfur purple bacteria similar to Blastochloris sulfoviridis and Rhodomicrobium vannielii were isolatd from the mats developing at high (50.6-49.4 degrees C) and low temperatures (45-20 degrees C). Purple sulfur bacteria Allochromatium sp. and Thiocapsa sp., as well as green sulfur bacteria Chlorobium sp., were revealedin low-temperature mats. Truly thermophilic purple and gree sulfur bacteria were not found in the spring. Anoxygenic phototrophic bacteria found in the spring were typical of the sulfuret communities, for which the sulfur cycle is mandatory. The presence of aerobic bacteriochlorophylla-containing bacteria identified as Agrobacterium (Rhizobium) tumifaciens in the mesophilic (20 degrees C) mat is of interest.

  15. Interaction and Synergism of Microbial Fuel Cell Bacteria within Methanogenesis

    Science.gov (United States)

    Klaus, David

    2004-01-01

    Biological hydrogen production from waste biomass has both terrestrial and Martian advanced life support applications. On earth, biological hydrogen production is being explored as a greenhouse neutral form of clean and efficient energy. In a permanently enclosed space habitat, carbon loop closure is required to reduce mission costs. Plants are grown to revitalize oxygen supply and are consumed by habitat inhabitants. Unharvested portions must then be recycled for reuse in the habitat. Several biological degradation techniques exist, but one process, biophotolysis, can be used to produce hydrogen from inedible plant biomass. This process is two-stage, with one stage using dark fermentation to convert plant wastes into organic acids. The second stage, photofermentation, uses photoheterotrophic purple non-sulfur bacteria with the addition of light to turn the organic acids into hydrogen and carbon dioxide. Such a system can prove useful as a co-generation scheme, providing some of the energy needed to power a larger primary carbon recovery system, such as composting. Since butyrate is expected as one of the major inputs into photofermentation, a characterization study was conducted with the bacterium Rhodobacter sphaeroides SCJ, a novel photoheterotrophic non-sulfur purple bacteria, to examine hydrogen production performance at 10 mM-100 mM butyrate concentrations. As butyrate levels increased, hydrogen production increased up to 25 mM, and then decreased and ceased by 100 mM. Additionally, lag phase increased with butyrate concentration, possibly indicating some product inhibition. Maximal substrate conversion efficiency was 8.0%; maximal light efficiency was 0.89%; and maximal hydrogen production rate was 7.7 Umol/mg/cdw/hr (173 ul/mg cdw/hr). These values were either consistent or lower than expected from literature.

  16. Manufacturing process influences properties of probiotic bacteria

    OpenAIRE

    Grzeskowiak, Lukasz; Isolauri, Erika; Salminen, Seppo; Gueimonde Fernández, Miguel

    2011-01-01

    Production and manufacturing methods and the food carrier may influence the properties of probiotic strains, and have an impact on the outcome of clinical intervention studies. The aim of the present study was to establish whether the properties of a specific probiotic strain, Lactobacillus rhamnosus GG, may differ depending on the product and source of the strain. In total, fifteen different L. rhamnosus isolates, among them fourteen labelled as L. rhamnosus GG, were isolated from specific p...

  17. Microbially influenced corrosion communities associated with fuel-grade ethanol environments.

    Science.gov (United States)

    Williamson, Charles H D; Jain, Luke A; Mishra, Brajendra; Olson, David L; Spear, John R

    2015-08-01

    Microbially influenced corrosion (MIC) is a costly problem that impacts hydrocarbon production and processing equipment, water distribution systems, ships, railcars, and other types of metallic infrastructure. In particular, MIC is known to cause considerable damage to hydrocarbon fuel infrastructure including production, transportation, and storage systems, often times with catastrophic environmental contamination results. As the production and use of alternative fuels such as fuel-grade ethanol (FGE) increase, it is important to consider MIC of engineered materials exposed to these "newer fuels" as they enter existing infrastructure. Reports of suspected MIC in systems handling FGE and water prompted an investigation of the microbial diversity associated with these environments. Small subunit ribosomal RNA gene pyrosequencing surveys indicate that acetic-acid-producing bacteria (Acetobacter spp. and Gluconacetobacter spp.) are prevalent in environments exposed to FGE and water. Other microbes previously implicated in corrosion, such as sulfate-reducing bacteria and methanogens, were also identified. In addition, acetic-acid-producing microbes and sulfate-reducing microbes were cultivated from sampled environments containing FGE and water. Results indicate that complex microbial communities form in these FGE environments and could cause significant MIC-related damage that may be difficult to control. How to better manage these microbial communities will be a defining aspect of improving mitigation of global infrastructure corrosion. PMID:26092755

  18. Salinity influence on soil microbial respiration rate of wetland in the Yangtze River estuary through changing microbial community

    Institute of Scientific and Technical Information of China (English)

    Xue Fei Xi; Lei Wang; Jia Jun Hu; Yu Shu Tang; Yu Hu; Xiao Hua Fu; Ying Sun

    2014-01-01

    Estuarine wetland,where freshwater mixes with salt water,comprises different regions (rivers and marine ecosystems) with significantly varying tidal salinities.Two sampling areas,ZXS and JS,were selected to investigate the effect of tidal salinity on soil respiration (SR).ZXS and JS were located in Zhongxia Shoal and Jiangyanan Shoal of Jiuduansha Wetland respectively,with similar elevation and plant species,but significantly different in salinity.The results showed that with almost identical plant biomass,the SR and soil microbial respiration (SMR) of the tidal wetland with lower salinity (JS) were significantly higher than those of the tidal wetland with higher salinity (ZXS) (p < 0.05).However,unlike SMR and SR,the difference in the soil microbial biomass (SMB) was not significant (p > 0.05) with the SMB of ZXS a little higher than that of JS.The higher SMR and SR of JS may be closely connected to the soil microbial community structures and amount of dominant bacteria.Abundant β-and γ-Proteobacteria and Actinobacteria in JS soil,which have strong heterotrophic metabolic capabilities,could be the main reason for higher SMR and SR,whereas a high number of ε-Proteobacteria in ZXS,some of which have carbon fixation ability,could be responsible for relatively lower carbon output.Path analysis indicated that soil salinity had the maximum negative total influencing coefficient with SMR among the various soil physical and chemical factors,suggesting that higher soil salinity,restricting highly heterotrophic bacteria,is the principle reason for lower SMR and SR in the ZXS.

  19. Bacteria with Phosphate Solubilizing Capacity Alter Mycorrhizal Fungal Growth Both Inside and Outside the Root and in the Presence of Native Microbial Communities.

    Science.gov (United States)

    Ordoñez, Yuli Marcela; Fernandez, Belen Rocio; Lara, Lidia Susana; Rodriguez, Alia; Uribe-Vélez, Daniel; Sanders, Ian R

    2016-01-01

    Arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing Pseudomonas bacteria (PSB) could potentially interact synergistically because PSB solubilize phosphate into a form that AMF can absorb and transport to the plant. However, very little is known about the interactions between these two groups of microorganisms and how they influence the growth of each other. We tested whether different strains of bacteria, that have the capacity to solubilize phosphate, are able to grow along AMF hyphae and differentially influence the growth of AMF both outside the roots of carrot in in vitro conditions and inside the roots of potato in the presence of a microbial community. We found strong effects of AMF on the growth of the different bacterial strains. Different bacterial strains also had very strong effects on the growth of AMF extraradical hyphae outside the roots of carrot and on colonization of potato roots by AMF. The differential effects on colonization occurred in the presence of a microbial community. Our results show that these two important groups of rhizosphere microorganisms indeed interact with each other. Such interactions could potentially lead to synergistic effects between the two groups but this could depend on whether the bacteria truly solubilize phosphate in the rhizosphere in the presence of microbial communities. PMID:27253975

  20. Bacteria with Phosphate Solubilizing Capacity Alter Mycorrhizal Fungal Growth Both Inside and Outside the Root and in the Presence of Native Microbial Communities

    Science.gov (United States)

    Lara, Lidia Susana; Rodriguez, Alia; Uribe-Vélez, Daniel; Sanders, Ian R.

    2016-01-01

    Arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing Pseudomonas bacteria (PSB) could potentially interact synergistically because PSB solubilize phosphate into a form that AMF can absorb and transport to the plant. However, very little is known about the interactions between these two groups of microorganisms and how they influence the growth of each other. We tested whether different strains of bacteria, that have the capacity to solubilize phosphate, are able to grow along AMF hyphae and differentially influence the growth of AMF both outside the roots of carrot in in vitro conditions and inside the roots of potato in the presence of a microbial community. We found strong effects of AMF on the growth of the different bacterial strains. Different bacterial strains also had very strong effects on the growth of AMF extraradical hyphae outside the roots of carrot and on colonization of potato roots by AMF. The differential effects on colonization occurred in the presence of a microbial community. Our results show that these two important groups of rhizosphere microorganisms indeed interact with each other. Such interactions could potentially lead to synergistic effects between the two groups but this could depend on whether the bacteria truly solubilize phosphate in the rhizosphere in the presence of microbial communities. PMID:27253975

  1. Bacteria with Phosphate Solubilizing Capacity Alter Mycorrhizal Fungal Growth Both Inside and Outside the Root and in the Presence of Native Microbial Communities.

    Directory of Open Access Journals (Sweden)

    Yuli Marcela Ordoñez

    Full Text Available Arbuscular mycorrhizal fungi (AMF and phosphate solubilizing Pseudomonas bacteria (PSB could potentially interact synergistically because PSB solubilize phosphate into a form that AMF can absorb and transport to the plant. However, very little is known about the interactions between these two groups of microorganisms and how they influence the growth of each other. We tested whether different strains of bacteria, that have the capacity to solubilize phosphate, are able to grow along AMF hyphae and differentially influence the growth of AMF both outside the roots of carrot in in vitro conditions and inside the roots of potato in the presence of a microbial community. We found strong effects of AMF on the growth of the different bacterial strains. Different bacterial strains also had very strong effects on the growth of AMF extraradical hyphae outside the roots of carrot and on colonization of potato roots by AMF. The differential effects on colonization occurred in the presence of a microbial community. Our results show that these two important groups of rhizosphere microorganisms indeed interact with each other. Such interactions could potentially lead to synergistic effects between the two groups but this could depend on whether the bacteria truly solubilize phosphate in the rhizosphere in the presence of microbial communities.

  2. Microbially influenced corrosion under disbonded coatings on a line pipe

    Energy Technology Data Exchange (ETDEWEB)

    MacLeod, F.A.; Kiff, D.R.; Vosikovsky, O. [Canada Centre for Mineral and Energy Technology, Ottawa, ON (Canada). Metals Technology Labs.]|[Canada Centre for Mineral and Energy Technology, Ottawa, ON (Canada). Mineral Sciences Labs.

    1992-12-31

    The effect of microbial activity on stress corrosion cracking (SCC) under disbonded coating on a line pipe was investigated. Sulfate-reducing bacteria were of particular interest in this study. The test pipe consisted of an X65 (Grade 448) steel pipe, 4.5 m in length and 508 mm in diameter. Sections of the pipe were surrounded by soils excavated from Alberta and Ontario sites where SCC was detected. Microbial, chemical and physical parameters were monitored at regular time intervals. Bacterial enumeration and analysis for organic acids and ions were performed. Profiles of water content and redox potential were also obtained. It was found that redox potential values decreased with soil depth. The environments in all sections of the pipe were classified as aggressive toward metal as described by Booth et al. Tests showed the most severe pitting corrosion at the top surface of the pipe. The environment at this position had the highest redox potential. Enumeration data suggested that this position was the only location that contained sufficient nutrients to support a viable acid producing population. It has been demonstrated that sulfate-reducing and acid producing bacteria cause severe pitting corrosion. It was also concluded that the availability of nutrients to support corrosion-causing bacteria should be an important consideration when evaluating the potential for metallic corrosion in soil. 4 figs., 1 table

  3. Broad spectrum anti-microbial compounds producing bacteria from coast of Qingdao bays.

    Science.gov (United States)

    Khan, Muhammad Naseem; Li, Meng; Mirani, Zulfiqar Ali; Wang, Jingxue; Lin, Hong; Buzdar, Muhammad Aslam

    2015-03-01

    Anti-microbial resistance burden and hazard associated with chemical treatment of infections demanded for new anti-microbial natural products. Marine associated microorganisms are the enormous source of bioactive compounds. In this study we have isolated 272 marine bacteria among them 136 (50%) were antagonistic to at least one of the four pathogenic strains Listeria monocytogenes, Vibrio cholerae, E. coli and S. aureus. Only two strains exhibited antibacterial activity against all four test strains, which were identified by 16S rDNA sequencing as Bacillus sp. DK1-SA11 and Vibrio sp. DK6-SH8. Marine isolate DK1-SA11 has potential to resist boiling temperature and pH 2-12. Furthermore cell free extract (CFE) inhibited all test organisms including superbug MRSA and pathogenic yeast Candida albicans. Marine isolate Bacillus sp. DK1-SA11 could be a potential combatant for the battle of drugs and bugs. PMID:25730803

  4. Accelerated cathodic reaction in microbial corrosion of iron due to direct electron uptake by sulfate-reducing bacteria

    International Nuclear Information System (INIS)

    Highlights: ► Corrosive SRB strain accelerates cathodic reaction of iron by direct electron uptake. ► Hydrogenotrophic control strain does not influence the cathodic reaction. ► Deposited ferrous sulfides do not stimulate the cathodic reaction. ► Deposited ferrous sulfides mediate electrical contact between metal and cells. - Abstract: Microbially influenced iron corrosion by sulfate-reducing bacteria (SRB) is conventionally attributed to the chemical corrosiveness of H2S, facilitated abiotic H+-reduction at deposited FeS, and biological consumption of chemically formed (‘cathodic’) H2. However, recent studies with corrosive SRB indicated direct consumption of iron-derived electrons rather than of H2 as a crucial mechanism. Here, we conducted potentiodynamic measurements with iron electrodes colonized by corrosive SRB. They significantly stimulated the cathodic reaction, while non-corrosive yet H2-consuming control SRB had no effect. Inactivation of the colonizing bacteria significantly reduced current stimulation, thus confirming biological catalysis rather than an abiotic cathodic effect of FeS.

  5. Microbially influenced corrosion on stainless steels in natural seawater; Kaisuichu ni okeru sutenresu ko no biseibutsu fushoku

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, H.; Miyuki, H. [Sumitomo Metal Industries Ltd., Osaka (Japan)

    1995-04-05

    The influence of microbes on the corrosion of steels in natural seawater is introduced laying stress on elucidated points. Biofilm consisting of various kinds of microbes is formed on the surface immersed in natural seawater. Adhered bacteria in this biofilm are isolated, and corrosion potential (Ecorr) in an experimental pure cultured system has been also investigated. Metabolic reaction of bacteria plays a part in microbially influenced corrosion (MIC), and reproduction of ennoblement of Ecorr is attempted by artificial means which simulates the breathing reaction of bacteria using refined oxidizing enzyme. It is made clear that corrosion behavior in natural seawater can be reproduced experimentally in a short period of time. This test method simulates the environment of the actual natural seawater well, and environmental MIC can be easily reproduced, which has been difficult in tests where conventional isolated bacteria are employed. 32 refs., 6 figs., 2 tabs.

  6. Microbial influenced corrosion in cargo oil tanks of crude oil tankers

    Energy Technology Data Exchange (ETDEWEB)

    Huang, R.T. [Chevron Shipping Co., San Francisco, CA (United States); McFarland, B.L. [Chevron Research and Technology Co., Richmond, CA (United States); Hodgman, R.Z. [Corrpro Companies Inc., Hayward, CA (United States)

    1997-09-01

    Excessive pitting corrosion in the uncoated bottom platings of cargo oil tanks was detected in newbuilt crude oil tankers only 2 to 5 years old, and was diagnosed as microbial influenced corrosion (MIC). Sulfate-reducing bacteria (SRB) concentrations reached as high as 100,000 to 10,000,000 per milliliter in the settled water at the bottom of the cargo oil tanks. Biocide treatment to control MIC was studied in the laboratory using microbial consortia isolated from cargo oil tank bottoms. Biocide treatment to control MIC was attempted experimentally, but was found to be impractical onboard tankers. A MIC mitigation strategy, employing an enhanced pitting inspection and repair program combined with the coating of the bottom platings, was developed and implemented for existing crude oil tankers. Considerations for improvement of future newbuild crude oil tankers are also presented.

  7. Investigation on behavior of bacteria in reservoir for microbial enhanced oil recovery; Biseibutsuho (MEOR) no tameno yusonai saikin katsudo ni kansuru chosa

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, K.; Tanaka, S.; Otsuka, M.; Nakaya, K. [Kansai Research Institute, Kyoto (Japan). Lifescience Research Center; Maezumi, S.; Yazawa, N. [Japan National Oil Corp., Tokyo (Japan). Technology Research Center; Hong, C.; Chida, T.; Enomoto, H. [Tohoku University, Miyagi (Japan). Graduate School of Engineering

    2000-07-01

    Behavior of bacteria activated in reservoir though molasses-injection-tests, was investigated using the restriction fragment length polymorphism analysis with the polymerase chain reaction (PCR-RFLP) method, for elucidating potential bacteria to suppress in situ growth of microbes to be injected into the reservoir in the microbial enhanced oil recovery (MEOR) process. As a result, some bacteria belonging to Enterobacteriaceae species or their close relative species were grown predominantly in the reservoir, among bacteria inhibiting in the ground-water. The foregoing indicates that behavior of these bacteria in reservoir must be taken into consideration when giving a full account of behavior of microbes to be injected into the reservoir to put the MEOR process into operation. Potential proliferation using molasses to activate those bacteria was also estimated on the laboratory tests, to clarify the growth of microbes to be injected into the reservoir to operate the MEOR process. In consequence, it became clear that these bacteria have a potential growth exceeding 10{sup 8} CFU/ml, utilizing molasses. These facts indicated that microbes to be injected into the reservoir at the MEOR field tests are necessary to grow more excellently than bacteria inhabiting in the ground-water. In addition, as flow, the injection fluid is influenced by reservoir heterogeneity caused by injection of molasses, it was inferred that microbes to be injected into the reservoir at the MEOR field process are also necessary to grow more remarkably than bacteria inhabiting in the reservoir brine at high permeability zones and bacteria inhabiting in the reservoir rock. Furthermore, the results of the functional testing for MEOR conducted in the presence of bacteria activated through molasses-injection-tests indicated the importance of effective use of microbes to be injected, taking into account the characteristics of the reservoir and function for MEOR of those microbes. (author)

  8. Microbial Diversity of Planctomycetes and Related Bacteria in Wetlands with Different Anthropogenic Disturbances

    Institute of Scientific and Technical Information of China (English)

    Yu Wang; Guibing Zhu; Erwin van der Biezen; Mike S M Jetten; Chengqing Yin

    2013-01-01

    The diversity of Planctomycetes and related bacteria in 3 types of freshwater wetlands with different anthropogenic disturbances were investigated by cloning and sequencing PCR-amplified partial 16S rRNA genes.Three clone libraries were constructed using 16S rRNA-targeted forward PCR primer specific for Planctomycetales and general bacterial reverse primer.Phylogenetic analysis of the 16S rRNA gene sequences defined 95 operational taxonomic units (OTUs) with 163 sequences.The clone libraries covered a wide microbial diversity of Proteobacteria and the Planctomycetes-Verrucomicrobia-Chlamydiales (PVC) superphylum.The majority of the OTUs were related to the phylum of Planctomycetes (33 OTUs),Proteobacteria (22 OTUs) and Verrucomicrobia (22 OTUs).Four known genera from the Planctomycetes phylum were all detected.The genus Pirellula (18 OTUs) dominated the Planetomycetes community,but different patterns of distribution were observed in the wetlands.The littoral wetlands of Baiyangdian Lake with the least anthropogenic disturbances covered more species and showed the highest biodiversity.However,the Jiaxing paddy fields with the highest anthropogenic disturbances showed a higher biodiversity than that in the riparian wetlands of the North Canal.Bacteria distantly related to anammox bacteria were also detected with a small proportion (4 OTUs).It showed that wetlands hold a great biodiversity of phyla Planctomycetes and related bacteria; furthermore,there is ample opportunity to discover novel phylotypes of Planctomycctes in the wctland ecosystems.

  9. Soil Bacteria Population Dynamics Following Stimulation for Ureolytic Microbial-Induced CaCO3 Precipitation.

    Science.gov (United States)

    Gat, Daniella; Ronen, Zeev; Tsesarsky, Michael

    2016-01-19

    Microbial-induced CaCO3 precipitation (MICP) via urea-hydrolysis (ureolysis) is an emerging soil improvement technique for various civil engineering and environmental applications. In-situ application of MICP in soils is performed either by augmenting the site with ureolytic bacteria or by stimulating indigenous ureolytic bacteria. Both of these approaches may lead to changes in the indigenous bacterial population composition and to the accumulation of large quantities of ammonium. In this batch study, effective ureolysis was stimulated in coastal sand from a semiarid environment, with low initial ureolytic bacteria abundance. Two different carbon sources were used: yeast-extract and molasses. No ureolysis was observed in their absence. Ureolysis was achieved using both carbon sources, with a higher rate in the yeast-extract enrichment resulting from increased bacterial growth. The changes to the indigenous bacterial population following biostimulation of ureolysis were significant: Bacilli class abundancy increased from 5% in the native sand up to 99% in the yeast-extract treatment. The sand was also enriched with ammonium-chloride, where ammonia-oxidation was observed after 27 days, but was not reflected in the bacterial population composition. These results suggest that biostimulation of ureolytic bacteria can be applied even in a semiarid and nutrient-poor environment using a simple carbon source, that is, molasses. The significant changes to bacterial population composition following ureolysis stimulation could result in a decrease in trophic activity and diversity in the treated site, thus they require further attention. PMID:26689904

  10. Ecological parameters influencing microbial diversity and stability of traditional sourdough.

    Science.gov (United States)

    Minervini, Fabio; De Angelis, Maria; Di Cagno, Raffaella; Gobbetti, Marco

    2014-02-01

    The quality of some leavened, sourdough baked goods is not always consistent, unless a well propagated sourdough starter culture is used for the dough fermentation. Among the different types of sourdough used, the traditional sourdough has attracted the interest of researchers, mainly because of its large microbial diversity, especially with respect to lactic acid bacteria. Variation in this diversity and the factors that cause it will impact on quality and is the subject of this review. Sourdough microbial diversity is mainly caused by the following factors: (i) sourdough is obtained through spontaneous, multi-step fermentation; (ii) it is propagated using flour, whose nutrient content may vary according to the batch and to the crop, and which is naturally contaminated by microorganisms; and (iii) it is propagated under peculiar technological parameters, which vary depending on the historical and cultural background and type of baked good. In the population dynamics leading from flour to mature sourdough, lactic acid bacteria (several species of Lactobacillus sp., Leuconostoc sp., and Weissella sp.) and yeasts (mainly Saccharomyces cerevisiae and Candida sp.) outcompete other microbial groups contaminating flour, and interact with each other at different levels. Ecological parameters qualitatively and quantitatively affecting the dominant sourdough microbiota may be classified into specific technological parameters (e.g., percentage of sourdough used as inoculum, time and temperature of fermentation) and parameters that are not fully controlled by those who manage the propagation of sourdough (e.g., chemical, enzyme and microbial composition of flour). Although some sourdoughs have been reported to harbour a persistent dominant microbiota, the stability of sourdough ecosystem during time is debated. Indeed, several factors may interfere with the persistence of species and strains associations that are typical of a given sourdough: metabolic adaptability to the

  11. Influence of oxytetracycline on the structure and activity of microbial community in wheat rhizosphere soil

    Institute of Scientific and Technical Information of China (English)

    YANG Qingxiang; ZHANG Jing; ZHU Kongfang; ZHANG Hao

    2009-01-01

    The microbial community composition in wheat rhizosphere was analyzed by detecting colony forming units (CFUs) in agar plates. The total CFUs in rhizosphere were 1.04×109/g soil with 9.0×108/g bacteria, 1.37×108/g actinomyces and 3.6×106/g fungi. The 10 dominant bacteria were isolated from wheat rhizosphere and were grouped into genus Bacillus according to their full length 16S rRNA gene sequences. Although belonging to the same genus, the isolated strains exhibited different sensitivities to oxytetracycline. When a series of the rhizosphere soil was exposed under various concentrations of oxytetracycline, the microbial community structure was highly affected with significant decline of CFUs of bacteria and actinomyces (22.2% and 31.7% at 10 mg/kg antibiotic, respectively). This inhibition was clearly enhanced with the increase exposure dosage of antibiotic and could not be eliminated during 30 d incubation. There was no obvious influence of this treatment on fungi population. Among the four soil enzymes (alkaline phosphatase, acidic phosphatase, dehydrogenase and urease), only alkaline phosphatase was sensitive to oxytetracycline exposure with 41.3% decline of the enzyme activity at 10 mg/kg antibiotic and further decrease of 64.3%-80.8% when the dosage over 30 mg/kg.

  12. Microbial consortium influence upon steel corrosion rate, using the electrochemical impedance spectroscopy technique

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Gayosso, M.J.; Ruiz-Ordaz, N. [Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional. Prolongacion de Carpio y Plan de Ayala, Mexico, D.F, C.P. 11340 (Mexico); Zavala-Olivares, G.; Garcia-Esquivel, R. [Instituto Mexicano del Petroleo, Grupo de Corrosion. Eje Central Lazaro Cardenas 152, Col. San Bartolo Atepehuacan, Mexico, D.F, C.P. 07730 (Mexico); Mora-Mendoza, J.L. [Petroleos Mexicanos, Marina Nacional 329, B-1, piso 8, Colonia Huasteca, CP 11311, Mexico, D.F. (Mexico)

    2004-09-01

    The Electrochemical Impedance Technique was used to evaluate the influence of a microbial consortium, isolated from a gas pipeline, upon API XL52 steel corrosion rate. The bacteria growth exhibited two different kinetics behavior, one for the planktonic and the other for the sessile phase. The sessile bacteria were found to be the main responsible for the corrosion rate increment observed during the experiments and no relationship between the planktonic microorganisms and the corrosion rate increment was found. The diagrams obtained from the electrochemical impedance measurements, indicated a biofilm formation and that the system changed from activation to diffusion control. Although the system was under diffusion control, an increment on the corrosion rate was detected, and a localized corrosion process was induced. The results were complemented with some surface analysis using Scanning Electron Microscopy. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  13. Fermentation couples Chloroflexi and sulfate-reducing bacteria to Cyanobacteria in hypersaline microbial mats

    Directory of Open Access Journals (Sweden)

    Jackson Z Lee

    2014-02-01

    Full Text Available Past studies of hydrogen cycling in hypersaline microbial mats have shown an active nighttime cycle, with production largely from Cyanobacteria and consumption from sulfate-reducing bacteria (SRB. However, the mechanisms and magnitude of hydrogen cycling have not been extensively studied. Two mats types near Guerrero Negro, Mexico -- permanently submerged Microcoleus microbial mats (GN-S, and intertidal Lyngbya microbial mats (GN-I -- were used in microcosm diel manipulation experiments with 3-(3,4-dichlorophenyl-1,1-dimethylurea (DCMU, molybdate, ammonium addition, and physical disruption to understand the processes responsible for hydrogen cycling between mat microbes. Across microcosms, H2 production occurred under dark anoxic conditions with simultaneous production of a suite of organic acids. H2 production was not significantly affected by inhibition of nitrogen fixation, but rather appears to result from constitutive fermentation of photosynthetic storage products by oxygenic phototrophs. Comparison to accumulated glycogen and to CO2 flux indicated that, in the GN-I mat, fermentation released almost all of the carbon fixed via photosynthesis during the preceding day, primarily as organic acids. Across mats, although oxygenic and anoxygenic phototrophs were detected, cyanobacterial [NiFe]-hydrogenase transcripts predominated. Molybdate inhibition experiments indicated that SRBs from a wide distribution of dsrA phylotypes were responsible for H2 consumption. Incubation with 13C-acetate and nanoSIMS (secondary ion mass-spectrometry indicated higher uptake in both Chloroflexi and SRBs relative to other filamentous bacteria. These manipulations and diel incubations confirm that Cyanobacteria were the main fermenters in Guerrero Negro mats and that the net flux of nighttime fermentation byproducts (not only hydrogen was largely regulated by the interplay between Cyanobacteria, SRBs, and Chloroflexi.

  14. Microbially influenced corrosion of buried pipelines and its control; Dojo maisetsu pipeline no biseibutsu fushoku to sono taisaku

    Energy Technology Data Exchange (ETDEWEB)

    Kajiyama, F. [Tokyo Gas Co. Ltd., Tokyo (Japan)

    1997-08-25

    This paper describes microbially influenced corrosion (MIC) on buried pipelines and its preventive measures. Major microorganisms involved in the corrosion include iron bacteria, iron oxidized bacteria, sulfur oxidized bacteria, sulfate reduced bacteria, and methane producing bacteria, which are largely divided into aerobic and anaerobic bacteria. There is high negative correlation between oxidation-reduction potential `E{sub h}` and pH of soils, and activity regions of each microorganism correspond to each region determined by E{sub h} - pH. According to the result of experimentally measuring the MIC rate in cast iron pipes, the rate was found to decrease in the order of iron bacteria > iron oxidized bacteria > sulfate reduced bacteria. As a first measure to prevent MIC, it is necessary to isolate pipes from soil. The present study disclosed that it is absolutely necessary to apply a coating having high insulation performance and take measures of cathodic protection, and that the corrosion may be prevented if the conventionally recommended anti-corrosive potential is cleared and electric current is flowing into defective parts even if a defect has occurred in the coating. 26 refs., 10 figs., 1 tab.

  15. Influence of bacteria on film formation inhibiting corrosion

    International Nuclear Information System (INIS)

    Mild steel coupons were incubated separately in two bacterial cultures namely Pseudomonas flava and Pseudomonas stutzeri. A significant reduction in the corrosion rate was observed in presence of P. flava. With a view to understand the mechanisms of microbially influenced corrosion/corrosion inhibition, various electrochemical and biological experiments such as weight change measurements and electrochemical impedance spectroscopy (EIS) measurements were made. The exposed surfaces were examined using scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDAX). The scraped surface film was also examined using FT-IR (Fourier transform infra red) spectroscopy. The results suggest that P. flava have enhancing effect on corrosion inhibitive properties of phosphate film

  16. A mini-microbial fuel cell for voltage testing of exoelectrogenic bacteria

    Institute of Scientific and Technical Information of China (English)

    Xiaoxin CAO; Xia HUANG; Xiaoyuan ZHANG; Peng LIANG; Mingzbi FAN

    2009-01-01

    Current methods for testing the electricity generation capacity of isolates are time- and labor-consuming. This paper presents a rapid voltage testing system of exoelectrogenic bacteria called Quickscreen,which is based on a microliter microbial fuel cell(MFC).Geobacter sulfurreducens and Shewanella baltica were used as the model exoelectrogenic bacteria; Escherichia coli that cannot generate electricity was used as a negative control. It was found that the electricity generation capacity of the isolates could be determined within about five hours by using Quickscreen, and that its time was relatively rapid compared with the time needed by using larger MFCs. A parallel, stable, and low background voltage was achieved using titanium as a current collector in the blank run. The external resistance had little impact on the blank run during the initial period. The cathode with a five-hole configuration, used to hydrate the carbon cathode, gave higher cathode potential than that with a one-hole configuration. Steady discharge and current interrupt methods showed that the anode mostly con-tributed to the large internal resistance of the Quickscreen system. However, the addition of graphite felt decreased the resistance from 18 to 5 kΩ. This device was proved to be useful to rapidly evaluate the electricity generation capacity of different bacteria.

  17. Microscopic examination of distribution and phenotypic properties of phylogenetically diverse Chloroflexaceae-related bacteria in hot spring microbial mats

    DEFF Research Database (Denmark)

    Nübel, Ulrich; Bateson, Mary M; Vandieken, Verona;

    2002-01-01

    We investigated the diversity, distribution, and phenotypes of uncultivated Chloroflexaceae-related bacteria in photosynthetic microbial mats of an alkaline hot spring (Mushroom Spring, Yellowstone National Park). By applying a directed PCR approach, molecular cloning, and sequence analysis of 16S......-scale distribution. FISH was combined with oxygen microelectrode measurements, microscope spectrometry, and microautoradiography to examine their microenvironment, pigmentation, and carbon source usage. Abundant type C-related, filamentous bacteria were found to flourish within the cyanobacterium-dominated, highly...

  18. Microscopic Examination of Distribution and Phenotypic Properties of Phylogenetically Diverse Chloroflexaceae-Related Bacteria in Hot Spring Microbial Mats

    DEFF Research Database (Denmark)

    Nübel, U.; Bateson, Mary M.; Vandieken, V.;

    2002-01-01

    We investigated the diversity, distribution, and phenotypes of uncultivated Chloroflexaceae-related bacteria in photosynthetic microbial mats of an alkaline hot spring (Mushroom Spring, Yellowstone National Park). By applying a directed PCR approach, molecular cloning, and sequence analysis of 16S......-scale distribution. FISH was combined with oxygen microelectrode measurements, microscope spectrometry, and microautoradiography to examine their microenvironment, pigmentation, and carbon source usage. Abundant type C-related, filamentous bacteria were found to flourish within the cyanobacterium-dominated, highly...

  19. Succession of sulfur-oxidizing bacteria in the microbial community on corroding concrete in sewer systems.

    Science.gov (United States)

    Okabe, Satoshi; Odagiri, Mitsunori; Ito, Tsukasa; Satoh, Hisashi

    2007-02-01

    Microbially induced concrete corrosion (MICC) in sewer systems has been a serious problem for a long time. A better understanding of the succession of microbial community members responsible for the production of sulfuric acid is essential for the efficient control of MICC. In this study, the succession of sulfur-oxidizing bacteria (SOB) in the bacterial community on corroding concrete in a sewer system in situ was investigated over 1 year by culture-independent 16S rRNA gene-based molecular techniques. Results revealed that at least six phylotypes of SOB species were involved in the MICC process, and the predominant SOB species shifted in the following order: Thiothrix sp., Thiobacillus plumbophilus, Thiomonas intermedia, Halothiobacillus neapolitanus, Acidiphilium acidophilum, and Acidithiobacillus thiooxidans. A. thiooxidans, a hyperacidophilic SOB, was the most dominant (accounting for 70% of EUB338-mixed probe-hybridized cells) in the heavily corroded concrete after 1 year. This succession of SOB species could be dependent on the pH of the concrete surface as well as on trophic properties (e.g., autotrophic or mixotrophic) and on the ability of the SOB to utilize different sulfur compounds (e.g., H2S, S0, and S2O3(2-)). In addition, diverse heterotrophic bacterial species (e.g., halo-tolerant, neutrophilic, and acidophilic bacteria) were associated with these SOB. The microbial succession of these microorganisms was involved in the colonization of the concrete and the production of sulfuric acid. Furthermore, the vertical distribution of microbial community members revealed that A. thiooxidans was the most dominant throughout the heavily corroded concrete (gypsum) layer and that A. thiooxidans was most abundant at the highest surface (1.5-mm) layer and decreased logarithmically with depth because of oxygen and H2S transport limitations. This suggested that the production of sulfuric acid by A. thiooxidans occurred mainly on the concrete surface and the

  20. Microbial consortium influence upon steel corrosion rate, using polarisation resistance and electrochemical noise techniques

    International Nuclear Information System (INIS)

    The microbiologically influenced corrosion (MIC) is a process, which affects the oil industry, particularly the hydrocarbons extraction, transport and storage. MIC evaluation has been normally based upon microbiological tests, and just a few references mention alternating methods, such as the electrochemical techniques, which can be used as criteria for their evaluation. In this work, two different electrochemical laboratory techniques, polarisation resistance and electrochemical noise were used, in order to determine the corrosion behaviour of a microbial consortium, obtained from a gas transporting pipeline, located in the southeast of Mexico. The bacteria population growth was found to be different for sessile and plancktonic microorganisms. Moreover, long incubation times were required to reach the maximum concentration of sessile bacteria. The electrochemical techniques used in this study exhibited a similar tendency on the corrosion rate behaviour with time, and values above 0.3 mm year-1 were observed at the end of the experiments. The experiments were complemented with surface analysis. Scanning electron microscope observation of APIXL52 steel coupons, exposed to the consortium action, revealed bacteria presence, as well as a damaged steel surface. A type of localized corrosion was observed on the metal surface, and it was associated to the bacteria effect

  1. Microbial consortium influence upon steel corrosion rate, using polarisation resistance and electrochemical noise techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Gayosso, M.J.; Zavala Olivares, G.; Ruiz Ordaz, N.; Juarez Ramirez, C.; Garcia Esquivel, R.; Padilla Viveros, A

    2004-10-01

    The microbiologically influenced corrosion (MIC) is a process, which affects the oil industry, particularly the hydrocarbons extraction, transport and storage. MIC evaluation has been normally based upon microbiological tests, and just a few references mention alternating methods, such as the electrochemical techniques, which can be used as criteria for their evaluation. In this work, two different electrochemical laboratory techniques, polarisation resistance and electrochemical noise were used, in order to determine the corrosion behaviour of a microbial consortium, obtained from a gas transporting pipeline, located in the southeast of Mexico. The bacteria population growth was found to be different for sessile and plancktonic microorganisms. Moreover, long incubation times were required to reach the maximum concentration of sessile bacteria. The electrochemical techniques used in this study exhibited a similar tendency on the corrosion rate behaviour with time, and values above 0.3 mm year{sup -1} were observed at the end of the experiments. The experiments were complemented with surface analysis. Scanning electron microscope observation of APIXL52 steel coupons, exposed to the consortium action, revealed bacteria presence, as well as a damaged steel surface. A type of localized corrosion was observed on the metal surface, and it was associated to the bacteria effect.

  2. Influence of manure age and sunlight on the community structure of cattle fecal bacteria as revealed by Illumina sequencing

    Science.gov (United States)

    Wong, K.; Shaw, T. I.; Oladeinde, A.; Molina, M.

    2013-12-01

    Fecal pollution of environmental waters is a major concern for the general public because exposure to fecal-associated pathogens can have severe impacts on human health. Stream and river impairment due to fecal pollution is largely the result of agricultural activities in the United States. In the last few years, numerous metagenomic studies utilized next generation sequencing to develop microbial community profiles by massively sequencing the 16sRNA hypervariable region. This technology supports the application of water quality assessment such as pathogen detection and fecal source tracking. The bacteria communities of samples in these studies were determined when they were freshly collected; therefore, little is known about how feces age or how environmental stress influences the microbial ecology of fecal materials. In this study we monitored bacteria community changes in cattle feces for 57 days after excretion (day 0, 2, 4 8, 15, 22, 29, 43, 57) by sequencing the 16s variable region 4, using Illumnia MiSeq. Twelve cattle feces were studied; half of the samples were directly exposed to sunlight (unshaded) and half were shaded. Results indicate that the relative abundance (RA) profile in both shaded and unshaded samples rapidly changed from day 0 to 15, but stabilized from day 22 to 57. Firmcutes were the most abundant phylum (~40%) at day 0, but were reduced to bacteria community in the natural environment. According to the rarefaction curve analysis, richness of bacteria diversity in feces decreased as time progressed. Some pathogens such as Campylobacter were detected only at the beginning, meaning they substantially decayed during the course of our study. Overall, this study indicated: (1) sunlight can influence the community structure and (2) after excretion the fecal bacteria diversity can be significantly changed over time. Future studies should therefore use not only the microbial signature of fresh but also moderately aged fecal samples to develop more

  3. Incorporation of probiotic bacteria in whey cheese: decreasing the risk of microbial contamination.

    Science.gov (United States)

    Madureira, A Raquel; Pintado, Manuela E; Gomes, Ana M P; Malcata, F Xavier

    2011-07-01

    For dairy products that are consumed fresh, contamination by spoilage microorganisms and pathogens from the environment is a major concern. Contamination has been associated with a number of outbreaks of foodborne illnesses; however, consistent data pertaining to the microbial safety of whey cheeses specifically have not been reported. Hence, the goals of this research effort were (i) to manufacture a probiotic whey cheese with Bifidobacterium animalis and Lactobacillus casei and (ii) to assess the antimicrobial activity of these probiotics against a set of foodborne pathogens (Listeria innocua, Salmonella Enteritidis, and Staphylococcus aureus) and food spoilage microorganisms (Pseudomonas aeruginosa and Escherichia coli). Three ranges of these microbial contaminants were used for inoculation of cheeses: 10(3) to 10(4), 10(4) to 10(6), and 10(6) to 10(8) CFU/g. Inoculation in plain culture medium served as a control. The inhibition produced by the probiotics was calculated, and the major effect was found to be bacteriostatic. In specific cases, full inhibition was observed, i.e., by B. animalis against P. aeruginosa and by L. casei against Salmonella Enteritidis and L. innocua. Conversely, the least inhibition was detected for L. casei against P. aeruginosa. Our results suggest that use of these probiotic strains can extend the shelf life of whey cheeses and make them safer by delaying or preventing growth of common contaminant bacteria.

  4. The microbial logic behind the prevalence of incomplete oxidation of organic compounds by acetogenic bacteria in methanogenic environments

    NARCIS (Netherlands)

    Dolfing, J.

    2001-01-01

    Microbial degradation of organic material in methanogenic ecosystems is a multistep process in which subsequent groups use the products of the first groups of organisms in the chain as substrates. The acetogenic bacteria in these systems produce both H2 and acetate. In the present minireview a therm

  5. Influence of Asellus aquaticus on Escherichia coli, Klebsiella pneumoniae, Campylobacter jejuni and naturally occurring heterotrophic bacteria in drinking water

    DEFF Research Database (Denmark)

    Christensen, Sarah Christine; Nissen, Erling; Arvin, Erik;

    2012-01-01

    . aquaticus on microbial water quality in non-chlorinated drinking water in controlled laboratory experiments. Pure cultures of the indicator organisms Escherichia coli and Klebsiella pneumoniae and the pathogen Campylobacter jejuni as well as naturally occurring heterotrophic drinking water bacteria...... decreased over time, following a first order decay with half lives of 5.3, 18.4 and 1.3 days, respectively. A. aquaticus did not affect survival of indicators and pathogens substantially whereas HPC were influenced by presence of dead A. aquaticus. Growth rates increased with an average of 48% for bacteria...... grown on R-2A agar and an average of 83% for bacteria grown on yeast extract agar when dead A. aquaticus were present compared to no and living A. aquaticus present. A. aquaticus associated E. coli, K. pneumoniae and C. jejuni were measured (up to 25 per living and 500 per dead A. aquaticus) and so were...

  6. Monitoring exogenous and indigenous bacteria by PCR-DGGE technology during the process of microbial enhanced oil recovery.

    Science.gov (United States)

    Wang, Jun; Ma, Ting; Zhao, Lingxia; Lv, Jinghua; Li, Guoqiang; Zhang, Hao; Zhao, Ben; Liang, Fenglai; Liu, Rulin

    2008-06-01

    A field experiment was performed to monitor changes in exogenous bacteria and to investigate the diversity of indigenous bacteria during a field trial of microbial enhanced oil recovery (MEOR). Two wells (26-195 and 27-221) were injected with three exogenous strains and then closed to allow for microbial growth and metabolism. After a waiting period, the pumps were restarted and the samples were collected. The bacterial populations of these samples were analyzed by denaturing gradient gel electrophoresis (DGGE) with PCR-amplified 16S rRNA fragments. DGGE profiles indicated that the exogenous strains were retrieved in the production water samples and indigenous strains could also be detected. After the pumps were restarted, average oil yield increased to 1.58 and 4.52 tons per day in wells 26-195 and 27-221, respectively, compared with almost no oil output before the injection of exogenous bacteria. Exogenous bacteria and indigenous bacteria contributed together to the increased oil output. Sequence analysis of the DGGE bands revealed that Proteobacteria were a major component of the predominant bacteria in both wells. Changes in the bacteria population in the reservoirs during MEOR process were monitored by molecular analysis of the 16S rRNA gene sequence. DGGE analysis was a successful approach to investigate the changes in microorganisms used for enhancing oil recovery. The feasibility of MEOR technology in the petroleum industry was also demonstrated. PMID:18273653

  7. Fractionation of Mercury Stable Isotopes during Microbial Methylmercury Production by Iron- and Sulfate-Reducing Bacteria.

    Science.gov (United States)

    Janssen, Sarah E; Schaefer, Jeffra K; Barkay, Tamar; Reinfelder, John R

    2016-08-01

    The biological production of monomethylmercury (MeHg) in soils and sediments is an important factor controlling mercury (Hg) accumulation in aquatic and terrestrial food webs. In this study we examined the fractionation of Hg stable isotopes during Hg methylation in nongrowing cultures of the anaerobic bacteria Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132. Both organisms showed mass-dependent, but no mass-independent fractionation of Hg stable isotopes during Hg methylation. Despite differences in methylation rates, the two bacteria had similar Hg fractionation factors (αr/p = 1.0009 and 1.0011, respectively). Unexpectedly, δ(202)Hg values of MeHg for both organisms were 0.4‰ higher than the value of initial inorganic Hg after about 35% of inorganic Hg had been methylated. These results indicate that a (202)Hg-enriched pool of inorganic Hg was preferentially utilized as a substrate for methylation by these organisms, but that multiple intra- and/or extracellular pools supplied inorganic Hg for biological methylation. Understanding the controls of the Hg stable isotopic composition of microbially produced MeHg is important to identifying bioavailable Hg in natural systems and the interpretation of Hg stable isotopes in aquatic food webs.

  8. Fractionation of Mercury Stable Isotopes during Microbial Methylmercury Production by Iron- and Sulfate-Reducing Bacteria.

    Science.gov (United States)

    Janssen, Sarah E; Schaefer, Jeffra K; Barkay, Tamar; Reinfelder, John R

    2016-08-01

    The biological production of monomethylmercury (MeHg) in soils and sediments is an important factor controlling mercury (Hg) accumulation in aquatic and terrestrial food webs. In this study we examined the fractionation of Hg stable isotopes during Hg methylation in nongrowing cultures of the anaerobic bacteria Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132. Both organisms showed mass-dependent, but no mass-independent fractionation of Hg stable isotopes during Hg methylation. Despite differences in methylation rates, the two bacteria had similar Hg fractionation factors (αr/p = 1.0009 and 1.0011, respectively). Unexpectedly, δ(202)Hg values of MeHg for both organisms were 0.4‰ higher than the value of initial inorganic Hg after about 35% of inorganic Hg had been methylated. These results indicate that a (202)Hg-enriched pool of inorganic Hg was preferentially utilized as a substrate for methylation by these organisms, but that multiple intra- and/or extracellular pools supplied inorganic Hg for biological methylation. Understanding the controls of the Hg stable isotopic composition of microbially produced MeHg is important to identifying bioavailable Hg in natural systems and the interpretation of Hg stable isotopes in aquatic food webs. PMID:27392249

  9. Influence of Wastewater Discharge on the Metabolic Potential of the Microbial Community in River Sediments

    KAUST Repository

    Li, Dong

    2015-09-24

    To reveal the variation of microbial community functions during water filtration process in river sediments, which has been utilized widely in natural water treatment systems, this study investigates the influence of municipal wastewater discharge to streams on the phylotype and metabolic potential of the microbiome in upstream and particularly various depths of downstream river sediments. Cluster analyses based on both microbial phylogenetic and functional data collectively revealed that shallow upstream sediments grouped with those from deeper subsurface downstream regions. These sediment samples were distinct from those found in shallow downstream sediments. Functional genes associated with carbohydrate, xenobiotic, and certain amino acid metabolisms were overrepresented in upstream and deep downstream samples. In contrast, the more immediate contact with wastewater discharge in shallow downstream samples resulted in an increase in the relative abundance of genes associated with nitrogen, sulfur, purine and pyrimidine metabolisms, as well as restriction–modification systems. More diverse bacterial phyla were associated with upstream and deep downstream sediments, mainly including Actinobacteria, Planctomycetes, and Firmicutes. In contrast, in shallow downstream sediments, genera affiliated with Betaproteobacteria and Gammaproteobacteria were enriched with putative functions that included ammonia and sulfur oxidation, polyphosphate accumulation, and methylotrophic bacteria. Collectively, these results highlight the enhanced capabilities of microbial communities residing in deeper stream sediments for the transformation of water contaminants and thus provide a foundation for better design of natural water treatment systems to further improve the removal of contaminants. © 2015, Springer Science+Business Media New York.

  10. Influence of Wastewater Discharge on the Metabolic Potential of the Microbial Community in River Sediments.

    Science.gov (United States)

    Li, Dong; Sharp, Jonathan O; Drewes, Jörg E

    2016-01-01

    To reveal the variation of microbial community functions during water filtration process in river sediments, which has been utilized widely in natural water treatment systems, this study investigates the influence of municipal wastewater discharge to streams on the phylotype and metabolic potential of the microbiome in upstream and particularly various depths of downstream river sediments. Cluster analyses based on both microbial phylogenetic and functional data collectively revealed that shallow upstream sediments grouped with those from deeper subsurface downstream regions. These sediment samples were distinct from those found in shallow downstream sediments. Functional genes associated with carbohydrate, xenobiotic, and certain amino acid metabolisms were overrepresented in upstream and deep downstream samples. In contrast, the more immediate contact with wastewater discharge in shallow downstream samples resulted in an increase in the relative abundance of genes associated with nitrogen, sulfur, purine and pyrimidine metabolisms, as well as restriction-modification systems. More diverse bacterial phyla were associated with upstream and deep downstream sediments, mainly including Actinobacteria, Planctomycetes, and Firmicutes. In contrast, in shallow downstream sediments, genera affiliated with Betaproteobacteria and Gammaproteobacteria were enriched with putative functions that included ammonia and sulfur oxidation, polyphosphate accumulation, and methylotrophic bacteria. Collectively, these results highlight the enhanced capabilities of microbial communities residing in deeper stream sediments for the transformation of water contaminants and thus provide a foundation for better design of natural water treatment systems to further improve the removal of contaminants.

  11. Microbially influenced corrosion of copper nuclear fuel waste containers in a Canadian disposal vault

    International Nuclear Information System (INIS)

    An assessment of the potential for microbially influenced corrosion (MIC) of copper nuclear fuel waste containers in a Canadian disposal vault is presented. The assessment is based on a consideration of the microbial activity within a disposal vault, the reported cases of MIC of Cu alloys in the literature and the known corrosion behaviour of Cu. Because of the critical role of biofilms in the reported cases of MIC, their formation and properties are discussed in detail. Next, the literature on the MIC of Cu alloys is briefly reviewed. The various MIC mechanisms proposed are critically discussed and the implications for the corrosion of Cu containers considered. In the majority of literature cases, MIC depends on alternating aerated and deaerated environments, with accelerated corrosion being observed when fresh aerated water replaces stagnant water, e.g., the MIC of Cu-Ni heat exchangers in polluted seawater and the microbially influenced pitting of Cu water pipes. Finally, because of the predominance of corrosion by sulphate-reducing bacteria (SRB) in the MIC literature, the abiotic behaviour of Cu alloys in sulphide solutions is also reviewed. The effect of the evolving environment in a disposal vault on the extent and location of microbial activity is discussed. Biofilm formation on the container surface is considered unlikely throughout the container lifetime, but especially initially when the environmental conditions will be particularly aggressive. Microbial activity in areas of the vault away from the container is possible, however. Corrosion of the container could then occur if microbial metabolic by-products diffuse to the container surface. Sulphide, produced by the action of SRB are considered to be the most likely cause of container corrosion. It is concluded that the only likely form of MIC of Cu containers will result from sulphide produced by SRB diffusing to the container surface. A modelling procedure for predicting the extent of corrosion is

  12. Influence of process dynamics on the microbial diversity in a nitrifying biofilm reactor: Correlation analysis and simulation study.

    Science.gov (United States)

    Vannecke, Thomas P W; Bernet, Nicolas; Winkler, Mari K H; Santa-Catalina, Gaelle; Steyer, Jean-Philippe; Volcke, Eveline I P

    2016-09-01

    For engineers, it is interesting to gain insight in the effect of control strategies on microbial communities, on their turn influencing the process behavior and its stability. This contribution assesses the influence of process dynamics on the microbial community in a biofilm reactor for nitrogen removal, which was controlled according to several strategies aiming at nitrite accumulation. The process dataset, combining conventional chemical and physical data with molecular information, was analyzed through a correlation analysis and in a simulation study. During nitrate formation, an increased nitrogen loading rate (NLR) resulted in a drop of the bulk liquid oxygen concentration without resulting in nitrite accumulation. A biofilm model was able to reproduce the bulk liquid nitrogen concentrations in two periods before and after this increased NLR. As the microbial parameters calibrated for the ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in both periods were different, it was concluded that the increased NLR governed an AOB and NOB population shift. Based on the molecular data, it was assumed that each period was typified by one dominant AOB and probably several subdominant NOB populations. The control strategies for nitrite accumulation influenced the bulk liquid composition by controlling the competition between AOB and NOB. Biotechnol. Bioeng. 2016;113: 1962-1974. © 2016 Wiley Periodicals, Inc. PMID:26887287

  13. Microbial corrosion of steel in Toarcian argillite: potential influence of bio-films

    International Nuclear Information System (INIS)

    sulfate reduction. Then, the characterization of biodiversity of Tournemire argillite has shown the presence of bacteria within undisturbed argillite, as well as the potential development of exogenous microorganisms within disturbed areas. Indeed, the observed bacterial diversity tends to depend on the different oxygen and humidity conditions, and also probably on space availability. Furthermore, the interaction of argillite with steel coupons placed into boreholes filled with re-compacted argillite during 6 years has been described by Gaudin et al. (2009). This study highlighted that oxygen introduced in the boreholes during drilling was consumed slower than expected, but the presence of hematite tends to show that reducing conditions prevailing in the host rock may have been recovered within 6 years. Recently, the characterization of the microbial diversity at interfaces between steel coupons and argillite in similar boreholes after 10 years of interaction has been investigated. The bio-diversities differ depending on the steel type and the borehole considered, indicating the influence of both iron-clay interactions and in situ environmental conditions. Sulphate-reducing bacteria, iron-reducing bacteria and bacteria capable to develop at high temperatures were detected. These microorganisms can grow at the interfaces between materials in a very short period of time compared with planned durations of disposal. Experimental In this framework, in order to better understand the conditions favoring the formation of biofilm, as well as the impact of microorganisms on the durability of metallic components, an experimental methodology was designed to assess microbial corrosion of steel in contact with argillite. A synthetic solution representative of the Tournemire pore water percolates through cells containing steel coupons placed in contact with argillite. Various environmental conditions likely to prevail in a repository are tested. Different artificial communities of

  14. Microbially influenced corrosion: studies on enterobacteria isolated from seawater environment and influence of toxic metals on bacterial biofilm and bio-corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Bermond-Tilly, D.; Pineau, S.; Dupont-Morral, I. [Corrodys, 50 - Equeurdreville (France); Janvier, M.; Grimont, P.A.D. [Institut Pasteur, Unite BBPE, 75 - Paris (France)

    2004-07-01

    of microbial clusters and the increase production of the EPS by bacteria (Fang et al., 2002). This study was conducted to test the corrosive activity of Citrobacter freundii, Proteus mirabilis and Klebsiella planticola on carbon steel coupons and the influence of a toxic metal Cr(III) found in polluted marine environment) on these bacteria and the EPS production of the biofilm formed on carbon steel by appropriate in vitro experiments. (authors)

  15. Influence of Culture Media on Microbial Fingerprints Using Raman Spectroscopy.

    Science.gov (United States)

    Mlynáriková, Katarína; Samek, Ota; Bernatová, Silvie; Růžička, Filip; Ježek, Jan; Hároniková, Andrea; Šiler, Martin; Zemánek, Pavel; Holá, Veronika

    2015-11-24

    Raman spectroscopy has a broad range of applications across numerous scientific fields, including microbiology. Our work here monitors the influence of culture media on the Raman spectra of clinically important microorganisms (Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans). Choosing an adequate medium may enhance the reproducibility of the method as well as simplifying the data processing and the evaluation. We tested four different media per organism depending on the nutritional requirements and clinical usage directly on a Petri dish. Some of the media have a significant influence on the microbial fingerprint (Roosvelt-Park Institute Medium, CHROMagar) and should not be used for the acquisition of Raman spectra. It was found that the most suitable medium for microbiological experiments regarding these organisms was Mueller-Hinton agar.

  16. Antibiotics influence on lactic acid bacteria inhibiting gastrointestinal tract

    Directory of Open Access Journals (Sweden)

    Andreja Čanžek Majhenič

    2001-04-01

    Full Text Available Lactic acid bacteria (LAB are common inhabitants of the gastrointestinal (GI tract and have important role in maintaining the equilibrium of GI flora, which can be influenced by various factors like diets, antimicrobials and stress. Minimal inhibitory concentrations (MIC and minimal bactericidal concentrations (MBC of 6 antibiotics, commonly used in human medicine for 8 selected lactobacilli strains were determined by macrodilution and microdilution methods in liquid media and by diffusion method on agar plates. The effects of Penicillin G and Ampicillin on intestinal LAB were tested in vivoon mice as well. Lactobacilli were sensitive to Penicillin G, (penicillines and their derivatives and Erythromycin (macrolides by in vitro testing. Clyndamycin (pyranosid showed moderate inhibitory effect. All lactobacilli strains were resistant to Kanamycin and Neomycin (aminoglycosides, while L. salivarius IM 124 has shown extra resistance to Erythromycin and Clyndamycin. The influence of orally administered Ampicillin showed no significant influence on LAB count in mice faeces. The effect of Penicillin G on mice LAB total count was significant, while no effect of orally administered lactobacilli was determined.

  17. Factors influencing the purification efficiency of photosynthetic bacteria

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    One strain of photosynthetic bacteria (PSB) was isolated from substrate sludge offresh-water fishpond. Influence of the use level of PSB culture solution, illumination condition,temperature, salinity, the use level of copper sulfate and dipterex on the purification efficiency was investigated. The results showed that the optimum use level of PSB culture solution was 10 mg/L,and the purification efficiency at illumination was higher than that at black, and if the temperature was lower than 15℃, or the use level of sodium chloride, copper sulfate and dipterex were higherthan 10 000 mg/L, 0.4 mg/L and 2.0 mg/L, respectively, the purification efficiency dropped distinctly.

  18. Succession of Sulfur-Oxidizing Bacteria in the Microbial Community on Corroding Concrete in Sewer Systems† ▿

    OpenAIRE

    Okabe, Satoshi; Odagiri, Mitsunori; Ito, Tsukasa; Satoh, Hisashi

    2007-01-01

    Microbially induced concrete corrosion (MICC) in sewer systems has been a serious problem for a long time. A better understanding of the succession of microbial community members responsible for the production of sulfuric acid is essential for the efficient control of MICC. In this study, the succession of sulfur-oxidizing bacteria (SOB) in the bacterial community on corroding concrete in a sewer system in situ was investigated over 1 year by culture-independent 16S rRNA gene-based molecular ...

  19. Microbial dynamics in natural aquifers

    OpenAIRE

    Bajracharya, Bijendra Man

    2016-01-01

    Microorganisms in groundwater form ecosystems that can transform chemical compounds. Quantitatively understanding microbial dynamics in soils and groundwater is thus essential for pollutant dynamics and biogeochemistry in the subsurface. This dissertation addresses three factors influencing microbial dynamics in aquifers and soils, namely: (1) the influence of grazing on bacteria in eutrophic aquifers, posing the question whether the carrying capacity of bacteria, which has been observed i...

  20. Phylogenetic Evidence for the Existence of Novel Thermophilic Bacteria in Hot Spring Sulfur-Turf Microbial Mats in Japan

    OpenAIRE

    Yamamoto, Hiroyuki; Hiraishi, Akira; Kato, Kenji; Chiura, Hiroshi X.; Maki, Yonosuke; Shimizu, Akira

    1998-01-01

    So-called sulfur-turf microbial mats, which are macroscopic white filaments or bundles consisting of large sausage-shaped bacteria and elemental sulfur particles, occur in sulfide-containing hot springs in Japan. However, no thermophiles from sulfur-turf mats have yet been isolated as cultivable strains. This study was undertaken to determine the phylogenetic positions of the sausage-shaped bacteria in sulfur-turf mats by direct cloning and sequencing of 16S rRNA genes amplified from the bulk...

  1. Clay minerals and metal oxides strongly influence the structure of alkane-degrading microbial communities during soil maturation.

    Science.gov (United States)

    Steinbach, Annelie; Schulz, Stefanie; Giebler, Julia; Schulz, Stephan; Pronk, Geertje J; Kögel-Knabner, Ingrid; Harms, Hauke; Wick, Lukas Y; Schloter, Michael

    2015-07-01

    Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant 'seed bank'.

  2. On-line electrochemical monitoring of microbially influenced corrosion

    International Nuclear Information System (INIS)

    Newly emerging electrochemical measurement techniques can provide on-line, non-destructive monitoring of the average corrosion rate and indications of localized pitting corrosion together with insight into fundamental electrochemical mechanisms responsible for the corrosion process. This information is relevant to evaluating, monitoring, understanding and controlling microbially influenced corrosion (MIC). MIC of coupons exposed in sidestream devices on site or in laboratory-based experiments, where the corrosion response is accelerated by exposure to active consortia of microbes recovered from specific sites, can be utilized to evaluate mitigation strategies. The average corrosion rates can be determined by small amplitude cyclic voltametry (SACV), and AC impedance spectroscopy (EIS). EIS can also give insight into the mechanisms of the MIC and indications of localized corrosion. Pitting corrosion can be detected non-destructively with open circuit potential monitoring (OCP). OCP also responds to bacterial biofilm activities such as oxygen depletion and other electrochemical activities. Utilizing these methods, accelerated tests can be designed to direct the selection of materials, surface treatments of materials, and welding filler materials, as well as the optimization of chemical and mechanical countermeasures with the microbial consortia recovered and characterized from the specific sites of interest

  3. Understanding the performance of sulfate reducing bacteria based packed bed reactor by growth kinetics study and microbial profiling.

    Science.gov (United States)

    Dev, Subhabrata; Roy, Shantonu; Bhattacharya, Jayanta

    2016-07-15

    A novel marine waste extract (MWE) as alternative nitrogen source was explored for the growth of sulfate reducing bacteria (SRB). Variation of sulfate and nitrogen (MWE) showed that SRB growth follows an uncompetitive inhibition model. The maximum specific growth rates (μmax) of 0.085 and 0.124 h(-1) and inhibition constants (Ki) of 56 and 4.6 g/L were observed under optimized sulfate and MWE concentrations, respectively. The kinetic data shows that MWE improves the microbial growth by 27%. The packed bed bioreactor (PBR) under optimized sulfate and MWE regime showed sulfate removal efficiency of 62-66% and metals removal efficiency of 66-75% on using mine wastewater. The microbial community analysis using DGGE showed dominance of SRB (87-89%). The study indicated the optimum dosing of sulfate and cheap organic nitrogen to promote the growth of SRB over other bacteria. PMID:27085153

  4. Understanding the performance of sulfate reducing bacteria based packed bed reactor by growth kinetics study and microbial profiling.

    Science.gov (United States)

    Dev, Subhabrata; Roy, Shantonu; Bhattacharya, Jayanta

    2016-07-15

    A novel marine waste extract (MWE) as alternative nitrogen source was explored for the growth of sulfate reducing bacteria (SRB). Variation of sulfate and nitrogen (MWE) showed that SRB growth follows an uncompetitive inhibition model. The maximum specific growth rates (μmax) of 0.085 and 0.124 h(-1) and inhibition constants (Ki) of 56 and 4.6 g/L were observed under optimized sulfate and MWE concentrations, respectively. The kinetic data shows that MWE improves the microbial growth by 27%. The packed bed bioreactor (PBR) under optimized sulfate and MWE regime showed sulfate removal efficiency of 62-66% and metals removal efficiency of 66-75% on using mine wastewater. The microbial community analysis using DGGE showed dominance of SRB (87-89%). The study indicated the optimum dosing of sulfate and cheap organic nitrogen to promote the growth of SRB over other bacteria.

  5. Top-down controls on bacterial community structure: microbial network analysis of bacteria, T4-like viruses and protists

    OpenAIRE

    Chow, Cheryl-Emiliane T.; Kim, Diane Y.; Sachdeva, Rohan; Caron, David A.; Fuhrman, Jed A

    2013-01-01

    Characterizing ecological relationships between viruses, bacteria and protists in the ocean are critical to understanding ecosystem function, yet these relationships are infrequently investigated together. We evaluated these relationships through microbial association network analysis of samples collected approximately monthly from March 2008 to January 2011 in the surface ocean (0–5 m) at the San Pedro Ocean Time series station. Bacterial, T4-like myoviral and protistan communities were desc...

  6. INFLUENCE OF MICROBIAL SURFACTANTS ON THE GROWTH OF LEGUMES

    Directory of Open Access Journals (Sweden)

    Shcheglova N. S.

    2015-02-01

    Full Text Available The influence of biogenic surfactants — rhamnolipids, trehalose lipids — on the growth of legumes was investigated. Rhamnolipid surfactants — product of biosynthesis of Pseudomonas sp. PS-17 strain were extracted by Folch mixture from the culture liquid supernatant and trehalose lipid surfactants — from biomass of R. erythropolis Aс-50 strain. Вiocomplex PS, which is a mixture of rhamnolipids and polysaccharides was precipitated from culture liquid supernatantof Pseudomonas sp. PS-17 strain with acidification to pH 3. Seeds of alfalfa and winter vetch were treated before sowing with solutions of biosurfactants or with appropriate culture of nitrogen-fixing bacteria and were grown in vessels in the sand culture conditions. The influence of rhamnolipids and indoleacetic acid on rhizogenesis was set in the biotest with beans cuttings. The optimal concentration of biosurfactants (0.01 g/l was determined for pre-sowing treatment of alfalfa and winter vetch seeds, which promoted the growth of their aboveground mass by 16–20%. It was shown that treatment of seeds by biosurfactants improved the efficiency of winter vetch seeds inoculation by biopreparation of nitrogen-fixing microorganisms: an aboveground plant mass increased by 34%. It was shown that soaking of beans cuttings in a mixture of biocomplex PS and indoleacetic acid increased the number of formed roots on 26.7% and their weight — on 19.2% compared with the control which was indoleacetic acid. It was shown that biogenic surfactants (rhamnolipids, trehalose lipids stimulated the growth of legumes (alfalfa, vetch, contributed to the increase of vegetative mass and stimulated the formation of symbiosis of winter vetch with bacteria Rhizobium leguminosarum bv. viciae. It was determined that one of the mechanisms of biosurfactant influence on the plant growth was improving the efficiency of phytohormones, including indole-3-acetic acid.

  7. Constraints on mechanisms and rates of anaerobic oxidation of methane by microbial consortia: process-based modeling of ANME-2 archaea and sulfate reducing bacteria interactions

    Directory of Open Access Journals (Sweden)

    B. Orcutt

    2008-11-01

    Full Text Available Anaerobic oxidation of methane (AOM is the main process responsible for the removal of methane generated in Earth's marine subsurface environments. However, the biochemical mechanism of AOM remains elusive. By explicitly resolving the observed spatial arrangement of methanotrophic archaea and sulfate reducing bacteria found in consortia mediating AOM, potential intermediates involved in the electron transfer between the methane oxidizing and sulfate reducing partners were investigated via a consortium-scale reaction transport model that integrates the effect of diffusional transport with thermodynamic and kinetic controls on microbial activity. Model simulations were used to assess the impact of poorly constrained microbial characteristics such as minimum energy requirements to sustain metabolism and cell specific rates. The role of environmental conditions such as the influence of methane levels on the feasibility of H2, formate and acetate as intermediate species, and the impact of the abundance of intermediate species on pathway reversal were examined. The results show that higher production rates of intermediates via AOM lead to increased diffusive fluxes from the methane oxidizing archaea to sulfate reducing bacteria, but the build-up of the exchangeable species can cause the energy yield of AOM to drop below that required for ATP production. Comparison to data from laboratory experiments shows that under the experimental conditions of Nauhaus et al. (2007, none of the potential intermediates considered here is able to support metabolic activity matching the measured rates.

  8. A biogeographic distribution of magnetotactic bacteria influenced by salinity.

    Science.gov (United States)

    Lin, Wei; Wang, Yinzhao; Li, Bi; Pan, Yongxin

    2012-02-01

    Magnetotactic bacteria (MTB), which synthesize intracellular ferromagnetic magnetite and/or greigite magnetosomes, have significant roles in global iron cycling in aquatic systems, as well as sedimentary magnetism. The occurrence of MTB has been reported in aquatic environments from freshwater to marine ecosystems; however, the distribution of MTB across heterogeneous habitats remains unclear. Here we examined the MTB communities from diverse habitats across northern and southern China, using comprehensive transmission electron microscopy and comparison of 16S rRNA gene analyses. A total of 334 16S rRNA gene sequences were analyzed, representing the most comprehensive analysis on the diversity and distribution of MTB to date. The majority (95%) of sequences belong to the Alphaproteobacteria, whereas a population of giant magnetotactic rod is affiliated with the Nitrospirae phylum. By a statistical comparison of these sequence data and publicly available MTB sequences, we infer for the first time that the composition of MTB communities represents a biogeographic distribution across globally heterogeneous environments, which is influenced by salinity. PMID:21866181

  9. Microbial iron uptake in the naturally fertilized waters in the vicinity of Kerguelen Islands: phytoplankton–bacteria interactions

    Directory of Open Access Journals (Sweden)

    M. Fourquez

    2014-10-01

    Full Text Available Iron (Fe uptake by the microbial community and the contribution of three different size-fractions was determined during spring phytoplankton blooms in the naturally Fe fertilized area off Kerguelen Islands (KEOPS2. Total Fe uptake in surface waters was on average 34 ± 6 pmol Fe L−1 d−1, and microplankton (>25 μm size-fraction; 40–69% and pico-nanoplankton (0.8–25 μm size-fraction; 29–59% were the main contributors. The share of heterotrophic bacteria (0.2–0.8 μm size-fraction to total Fe uptake was low at all stations (1–2%. Iron uptake rates normalized to carbon biomass were highest for pico-nanoplankton above the Kerguelen plateau and for microplankton in the downstream plume. We also investigated the potential competition between heterotrophic bacteria and phytoplankton for the access to Fe. Bacterial Fe uptake rates normalized to carbon biomass were highest when bacteria were incubated in the absence of both micro- and pico-nanoplankton. The absence of microplankton resulted in a decrease in bacterial Fe uptake rates by up to 20-fold, while in incubations with the whole microbial community bacterial uptake rates were reduced by 2- to 8-fold. In Fe-fertilized waters, the bacterial Fe uptake rates normalized to carbon biomass were positively correlated with primary production. Taken together, these results demonstrate that heterotrophic bacteria are outcompeted by small sized phytoplankton cells for the access to Fe during the spring bloom development, most likely due to the limitation by organic matter. We conclude that the Fe and carbon cycles are tightly coupled and driven by a~complex interplay of competition and synergy between different members of the microbial community.

  10. Microbially influenced corrosion of stainless steel by manganese oxidizing microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Linhardt, P. [Technische Universitaet Wien, Technische Versuchs- und Forschungsanstalt (TVFA), Karlsplatz 13, 1040 Wien (Austria)

    2004-03-01

    Based on the corrosion behaviour of stainless steels in fresh water and on the electrochemical properties of higher manganese oxides, the mechanism ''Microbially influenced corrosion by manganese oxidizing microorganisms'' (MIC by MOMOs) is presented as the consequence of biomineralized manganese oxides in contact with the metal. Localized corrosion may develop at elevated but normally undercritical chloride concentration in the water. The mechanism was found useful in the analysis of certain cases of unexpected failure of stainless steel in fresh water. (Abstract Copyright [2004], Wiley Periodicals, Inc.) [German] Ausgehend vom Korrosionsverhalten nichtrostender Staehle in Suesswasser und den elektrochemischen Eigenschaften hoeherer Manganoxide wird der Mechanismus ''Mikrobiell beeinflusste Korrosion durch manganoxidierende Mikroorganismen'' als die Folge des Kontaktes von biomineralisiertem Braunstein mit dem metallischen Werkstoff beschrieben. Unter diesen Bedingungen kann Lokalkorrosion bei Chloridkonzentrationen im Wasser entstehen, die normalerweise als unkritisch angesehen werden. Der Mechanismus hat sich bei der Schadensanalyse bestimmter, unerwarteter Korrosionsfaelle bewaehrt. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  11. Microbial interactions involving sulfur bacteria : implications for the ecology and evolution of bacterial communities

    NARCIS (Netherlands)

    Overmann, J; van Gemerden, H

    2000-01-01

    A major goal of microbial ecology is the identification and characterization of those microorganisms which govern transformations in natural ecosystems. This review summarizes our present knowledge of microbial interactions in the natural sulfur cycle. Central to the discussion is the recent progres

  12. Antimicrobials Influence Bond Stiffness and Detachment of Oral Bacteria.

    Science.gov (United States)

    Song, L; Hou, J; van der Mei, H C; Veeregowda, D H; Busscher, H J; Sjollema, J

    2016-07-01

    Oral biofilm can never be fully removed by oral hygiene measures. Biofilm left behind after brushing is often left behind on the same sites and exposed multiple times to antimicrobials from toothpastes and mouthrinses, after which removal becomes increasingly difficult. On the basis of this observation, we hypothesize that oral bacteria adhering to salivary conditioning films become more difficult to remove after adsorption of antimicrobials due to stiffening of their adhesive bond. To verify this hypothesis, bacteria adhering to bare and saliva-coated glass were exposed to 3 different mouthrinses, containing chlorhexidine-digluconate, cetylpyridinium-chloride, or amine-fluoride, after which bacterial vibration spectroscopy was carried out or a liquid-air interface was passed over the adhering bacteria to stimulate their detachment. Brownian motion-induced nanoscopic vibration amplitudes of 4 oral streptococcal strains, reflecting their bond stiffness, decreased after exposure to mouthrinses. Concurrently, the percentage detachment of adhering bacteria upon the passage of a liquid-air interface decreased after exposure to mouthrinses. A buffer control left both vibration amplitudes and detachment percentages unaffected. Exposure to either of the selected mouthrinses yielded more positively charged bacteria by particulate microelectrophoresis, suggesting antimicrobial adsorption to bacterial cell surface components. To rule out that exposure of adhering bacteria to the mouthrinses stimulated polysaccharide production with an impact on their detachment, Fourier transform infrared spectroscopy was carried out on bacteria adhering to an internal reflection element, prior to and after exposure to the mouthrinses. Infrared absorption band areas indicated no significant change in amount of polysaccharides after exposure of adhering bacteria to mouthrinses, but wave number shifts demonstrated stiffening of polysaccharides in the bond, as a result of antimicrobial

  13. INFLUENCE OF MEAT MATURATION TO THE PRESENCE OF COLIFORM BACTERIA

    Directory of Open Access Journals (Sweden)

    Ľubomír Lopašovský

    2012-12-01

    Full Text Available Normal 0 21 false false false SK JA X-NONE The aim of our study was detection of coliforms bacteria and pH changes in the process of beef maturation. The number of coliforms bacteria were lower as 1 log cfu.g-1 in four samples and the highest coliforms bacteria count was 3.1 log cfu.g-1 after 1-st week of meat maturation. Average number of coliforms bacteria was lower as 1.43 log cfu.g-1.  The pH values of meat varied from 5.5 to 6.1 after 1-st week. Average value of pH was 5.75.  The number of coliforms bacteria were from 2.61 log cfu.g-1 to 3.35 log cfu.g-1 after 2-nd week of meat maturation. Average number of coliforms bacteria was 3.17 log cfu.g-1. The pH values of meat were from 6.0 to 6.2 after 2-nd week of meat maturation. Average value of pH was 6.05. doi:10.5219/181

  14. Microbially influenced corrosion (MIC) analyses of the BNGS-B vacuum building. Report No. 92-185-K. [BNGS (Bruce Nuclear Generating Station)

    Energy Technology Data Exchange (ETDEWEB)

    Jain, D.K.

    1992-01-01

    Microbially influenced corrosion (MIC) has been found to play a significant role in causing corrosion, especially in those industries which use natural waters. The most significant of the organisms found to cause corrosion are the sulphate-reducing bacteria (SRB), particularly with anoxic deposits or stagnant weirs. In May 1992, the Bruce Nuclear Generating Station B Vacuum Building was inspected for MIC after being in service for 10 years. This report provides results for both on-site MIC inspection and for microbiological analysis of sediments, water, and slime deposits for evidence of MIC bacteria.

  15. Influence of organic carbon sources and isotope exchange processes between water and nitrate on the fractionation of the stable isotopes 15N/14N and 18O/16O in dissolved nitrate during microbial dentrification in groundwater

    International Nuclear Information System (INIS)

    Stable isotopes of nitrate are commonly used to determine sources and degradation of nitrate. In this study, nitrite oxidizing bacteria were found to promote an oxygen isotope exchange between water and nitrate under anoxic conditions. Also, different carbon sources were found to influence the enrichment of stable isotopes in nitrate during microbial denitrification. Both results refine the stable isotope model of nitrate in respect to nitrate source determination and microbial nitrate reduction.

  16. Influence of hormonal contraceptives on microbial flora of gingival sulcus.

    Science.gov (United States)

    Klinger, G; Eick, S; Klinger, G; Pfister, W; Gräser, T; Moore, C; Oettel, M

    1998-06-01

    To determine a possible influence of two different hormonal contraceptives on bacterial microflora of gingival sulcus, subgingival plaque samples of 29 healthy women aged between 20 and 32 years were investigated bacteriologically before subjects took a contraceptive and 10 and 20 days after subjects started the medication. In 14 women, and oral contraceptive containing 0.02 mg ethinyl estradiol and 0.15 mg desogestrel (preparation A) was used, and 15 women took a contraceptive containing 0.03 mg ethinyl estradiol and 2.00 mg dienogest (preparation B) daily over 21 days. There were no changes in clinical parameters of the teeth investigated during 3 weeks of the study. The periodontopathogenic bacteria Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were never detected throughout the study. On the other hand, the periodontopathogenic species Prevotella intermedia was found in plaque samples of 22 women. The content of this microorganism showed only a little change between the pretreatment period and plaque sampling after 10 days of contraceptive treatment, but a striking increase occurred after 20 days of contraceptive treatment, especially in the preparation A group. In this respect, there was a significant difference between preparations A and B. PMID:9693397

  17. Differentiation in the microbial ecology and activity of suspended and attached bacteria in a nitritation-anammox process.

    Science.gov (United States)

    Park, Hongkeun; Sundar, Suneethi; Ma, Yiwei; Chandran, Kartik

    2015-02-01

    A directed differentiation between the biofilm and suspension was observed in the molecular microbial ecology and gene expression of different bacteria in a biofilm nitritation-anammox process operated at varying hydraulic residence times (HRT) and nitrogen loading rates (NLR). The highest degree of enrichment observed in the biofilm was of anaerobic ammonia-oxidizing bacteria (AMX) followed by that of Nitrospira spp. related nitrite-oxidizing bacteria (NOB). For AMX, a major shift from Candidatus "Brocadia fulgida" to Candidatus "Kuenenia stuttgartiensis" in both suspension and biofilm was observed with progressively shorter HRT, using discriminatory biomarkers targeting the hydrazine synthase (hzsA) gene. In parallel, expression of the hydrazine oxidoreductase gene (hzo), a functional biomarker for AMX energy metabolism, became progressively prominent in the biofilm. A marginal but statistically significant enrichment in the biofilm was observed for Nitrosomonas europaea related ammonia-oxidizing bacteria (AOB). In direct contrast to AMX, the gene expression of ammonia monooxygenase subunit A (amoA), a functional biomarker for AOB energy metabolism, progressively increased in suspension. Using gene expression and biomass concentration measures in conjunction, it was determined that signatures of AOB metabolism were primarily present in the biofilm throughout the study. On the other hand, AMX metabolism gradually shifted from being uniformly distributed in both the biofilm and suspension to primarily the biofilm at shorter HRTs and higher NLRs. These results therefore highlight the complexity and key differences in the microbial ecology, gene expression and activity between the biofilm and suspension of a nitritation-anammox process and the biokinetic and metabolic drivers for such niche segregation. PMID:25115980

  18. Microbial oxidation of dispersed graphite by nitrifying bacteria 2011.2

    Science.gov (United States)

    Zhu, Chunlin; Hao, Qingli; Huang, Yang; Yang, Jiazhi; Sun, Dongping

    2013-09-01

    A facile and green microbial method to produce graphite oxide nanosheets and nanoparticles is described. The obtained graphite oxide nanosheets have few layers with 0.7-1.5 nm height and 50-300 nm size. The carbon nanoparticles possess the size of 20-60 nm and the height of 2-4 nm.A facile and green microbial method to produce graphite oxide nanosheets and nanoparticles is described. The obtained graphite oxide nanosheets have few layers with 0.7-1.5 nm height and 50-300 nm size. The carbon nanoparticles possess the size of 20-60 nm and the height of 2-4 nm. Electronic supplementary information (ESI) available: Experimental section, characterization details and the mechanism of the oxidation process. Microscopic photographs of graphite during the microbial oxidation and the proposed mechanism of microbial oxidation of graphite. See DOI: 10.1039/c3nr02069j

  19. Rumen microbial communities influence metabolic phenotypes in lambs.

    Science.gov (United States)

    Morgavi, Diego P; Rathahao-Paris, Estelle; Popova, Milka; Boccard, Julien; Nielsen, Kristian F; Boudra, Hamid

    2015-01-01

    The rumen microbiota is an essential part of ruminants shaping their nutrition and health. Despite its importance, it is not fully understood how various groups of rumen microbes affect host-microbe relationships and functions. The aim of the study was to simultaneously explore the rumen microbiota and the metabolic phenotype of lambs for identifying host-microbe associations and potential biomarkers of digestive functions. Twin lambs, separated in two groups after birth were exposed to practices (isolation and gavage with rumen fluid with protozoa or protozoa-depleted) that differentially restricted the acquisition of microbes. Rumen microbiota, fermentation parameters, digestibility and growth were monitored for up to 31 weeks of age. Microbiota assembled in isolation from other ruminants lacked protozoa and had low bacterial and archaeal diversity whereas digestibility was not affected. Exposure to adult sheep microbiota increased bacterial and archaeal diversity independently of protozoa presence. For archaea, Methanomassiliicoccales displaced Methanosphaera. Notwithstanding, protozoa induced differences in functional traits such as digestibility and significantly shaped bacterial community structure, notably Ruminococcaceae and Lachnospiraceae lower up to 6 folds, Prevotellaceae lower by ~40%, and Clostridiaceae and Veillonellaceae higher up to 10 folds compared to microbiota without protozoa. An orthogonal partial least squares-discriminant analysis of urinary metabolome matched differences in microbiota structure. Discriminant metabolites were mainly involved in amino acids and protein metabolic pathways while a negative interaction was observed between methylotrophic methanogens Methanomassiliicoccales and trimethylamine N-oxide. These results stress the influence of gut microbes on animal phenotype and show the potential of metabolomics for monitoring rumen microbial functions. PMID:26528248

  20. Rumen microbial communities influence metabolic phenotypes in lambs

    Directory of Open Access Journals (Sweden)

    Diego P. Morgavi

    2015-10-01

    Full Text Available The rumen microbiota is an essential part of ruminants forging their nutrition and health. Despite its importance, it is not fully understood how various groups of rumen microbes affect host-microbe relationships and functions. The aim of the study was to simultaneously explore the rumen microbiota and the metabolic phenotype of lambs for identifying host-microbe associations and potential biomarkers of digestive functions. Twin lambs, separated in two groups after birth were exposed to practices (isolation and gavage with rumen fluid with protozoa or protozoa-depleted that differentially restricted the acquisition of microbes. Rumen microbiota, fermentation parameters, digestibility and growth were monitored for up to 31 weeks of age. Microbiota assembled in isolation from other ruminants lacked protozoa and had low bacterial and archaeal diversity whereas digestibility was not affected. Exposure to adult sheep microbiota increased bacterial and archaeal diversity independently of protozoa presence. For archaea, Methanomassiliicoccales displaced Methanosphaera. Notwithstanding, protozoa induced differences in functional traits such as digestibility and significantly shaped bacterial community structure, notably Ruminococcaceae and Lachnospiraceae lower up to 6 folds, Prevotellaceae lower by ~40%, and Clostridiaceae and Veillonellaceae higher up to 10 folds compared to microbiota without protozoa. An orthogonal partial least squares-discriminant analysis of urinary metabolome matched differences in microbiota structure. Discriminant metabolites were mainly involved in amino acids and protein metabolic pathways while a negative interaction was observed between methylotrophic methanogens Methanomassiliicoccales and trimethylamine N-oxide. These results stress the influence of gut microbes on animal phenotype and show the potential of metabolomics for monitoring rumen microbial functions.

  1. Microbial Communities Associated with Holothurians: Presence of Unique Bacteria in the Coelomic Fluid

    OpenAIRE

    Enomoto, Masaki; Nakagawa, Satoshi; Sawabe, Tomoo

    2012-01-01

    Marine invertebrates interact with various microorganisms ranging from pathogens to symbionts. One-to-one symbiosis between a single microbial species and a single host animal has served as a model for the study of host-microbe interactions. In addition, increasing attention has recently been focused on the complex symbiotic associations, e.g., associations between sponges and their symbionts, due to their biotechnological potential; however, relatively little is known about the microbial div...

  2. Characterization of the microbial community composition and the distribution of Fe-metabolizing bacteria in a creek contaminated by acid mine drainage.

    Science.gov (United States)

    Sun, Weimin; Xiao, Enzong; Krumins, Valdis; Dong, Yiran; Xiao, Tangfu; Ning, Zengping; Chen, Haiyan; Xiao, Qingxiang

    2016-10-01

    A small watershed heavily contaminated by long-term acid mine drainage (AMD) from an upstream abandoned coal mine was selected to study the microbial community developed in such extreme system. The watershed consists of AMD-contaminated creek, adjacent contaminated soils, and a small cascade aeration unit constructed downstream, which provide an excellent contaminated site to study the microbial response in diverse extreme AMD-polluted environments. The results showed that the innate microbial communities were dominated by acidophilic bacteria, especially acidophilic Fe-metabolizing bacteria, suggesting that Fe and pH are the primary environmental factors in governing the indigenous microbial communities. The distribution of Fe-metabolizing bacteria showed distinct site-specific patterns. A pronounced shift from diverse communities in the upstream to Proteobacteria-dominated communities in the downstream was observed in the ecosystem. This location-specific trend was more apparent at genus level. In the upstream samples (sampling sites just below the coal mining adit), a number of Fe(II)-oxidizing bacteria such as Alicyclobacillus spp., Metallibacterium spp., and Acidithrix spp. were dominant, while Halomonas spp. were the major Fe(II)-oxidizing bacteria observed in downstream samples. Additionally, Acidiphilium, an Fe(III)-reducing bacterium, was enriched in the upstream samples, while Shewanella spp. were the dominant Fe(III)-reducing bacteria in downstream samples. Further investigation using linear discriminant analysis (LDA) effect size (LEfSe), principal coordinate analysis (PCoA), and unweighted pair group method with arithmetic mean (UPGMA) clustering confirmed the difference of microbial communities between upstream and downstream samples. Canonical correspondence analysis (CCA) and Spearman's rank correlation indicate that total organic carbon (TOC) content is the primary environmental parameter in structuring the indigenous microbial communities

  3. Interactions between marine snow and heterotrophic bacteria: aggregate formation and microbial dynamics

    DEFF Research Database (Denmark)

    Grossart, H.P.; Kiørboe, Thomas; Tang, K.W.;

    2006-01-01

    bacteria depended on phytoplankton growth and aggregation dynamics. The community composition of especially attached bacteria significantly differed between the 2 algal cultures. Our study suggests that phytoplankton aggregation and vertical fluxes are closely linked to interactions between the marine...... well as abundance, colonization behaviour, and community composition of bacteria during the growth of 2 marine diatoms (Thalassiosira weissflogii and Navicula sp.) under axenic and non-axenic conditions. Community composition of free-living and attached bacteria during phytoplankton growth and...... aggregation was studied by amplification of 16S rRNA gene fragments and denaturing gradient gel electrophoresis (DGGE). Our results show that the presence of bacteria was a prerequisite for aggregation of T. weissflogii but not of Navicula sp. Occurrences of distinct populations of free-living and attached...

  4. Contribution of microbial influence corrosion to power-plant aging

    International Nuclear Information System (INIS)

    A summary of microbial induced corrosion (MIC) is presented. Occurrences of this type of corrosion in nuclear power generating plants systems are cited. Both safety and nonsafety systems have been attacked by MIC. This phenomena is discussed in relation to the potential effects it could have in the overall aging of the plant. Microbial involvement, types of metals affected and mitigation and prevention of MIC are also covered

  5. A summary of microbial influenced corrosion in nuclear power plants

    International Nuclear Information System (INIS)

    A summary of microbial induced corrosion (MIC) is presented. Occurrences of this type of corrosion in nuclear power generating plants systems are cited. Both safety and nonsafety systems have been attacked by MIC. This phenomena is discussed in relation to the potential effects it could have in the overall aging of the plant. Microbial involvement, types of metals affected and mitigation and prevention of MIC are also covered

  6. Selection of bacteria with favorable transport properties through porous rock for the application of microbial-enhanced oil recovery.

    Science.gov (United States)

    Jang, L K; Chang, P W; Findley, J E; Yen, T F

    1983-11-01

    This paper presents a bench-scale study on the transport in highly permeable porous rock of three bacterial species-Bacillus subtilis, Pseudomonas putida, and Clostridium acetobutylicum-potentially applicable in microbial-enhanced oil recovery processes. The transport of cells during the injection of bacterial suspension and nutrient medium was simulated by a deep bed filtration model. Deep bed filtration coefficients and the maximum capacity of cells in porous rock were measured. Low to intermediate ( approximately 10/ml) injection concentrations of cellular suspensions are recommended because plugging of inlet surface is less likely to occur. In addition to their resistance to adverse environments, spores of clostridia are strongly recommended for use in microbial-enhanced oil recovery processes since they are easiest among the species tested to push through porous rock. After injection, further transport of bacteria during incubation can occur by growth and mobility through the stagnant nutrient medium which fills the porous rock. We have developed an apparatus to study the migration of bacteria through a Berea sandstone core containing nutrient medium.

  7. Thermophilic hydrogen production from sludge pretreated by thermophilic bacteria: analysis of the advantages of microbial community and metabolism.

    Science.gov (United States)

    Zheng, He-Shan; Guo, Wan-Qian; Yang, Shan-Shan; Feng, Xiao-Chi; Du, Juan-Shan; Zhou, Xian-Jiao; Chang, Jo-Shu; Ren, Nan-Qi

    2014-11-01

    In this study, the effects of thermophilic bacteria pretreatment and elevated fermentation temperature on hydrogen production from sludge were examined. The highest hydrogen yield of 19.9mlH2g(-1) VSS was achieved at 55°C by using pretreated sludge, which was 48.6% higher than raw sludge without pretreatment, and 28.39% higher than when fermented at 35°C. To explore the internal factors of this superior hydrogen production performance, the microbial community and the metabolism analysis were performed by using high-throughput sequencing and excitation-emission matrix. The pretreated sludge showed better utilization of dissolved organic matter and less inhibition of metabolism, especially at thermophilic condition. The 454 sequencing data indicated that microbial abundance was distinctly reduced and extremely high proportion of hydrogen-producing bacteria was found in the thermophilic community (Thermoanaerobacterium accounted for 93.75%). Thus, the pretreated sludge and thermophilic condition showed significant advantages in the hydrogen production using waste sludge as substrate.

  8. Constraints on mechanisms and rates of anaerobic oxidation of methane by microbial consortia: process-based modeling of ANME-2 archaea and sulfate reducing bacteria interactions

    Directory of Open Access Journals (Sweden)

    B. Orcutt

    2008-05-01

    Full Text Available Anaerobic oxidation of methane (AOM is the main process responsible for the removal of methane generated in Earth's marine subsurface environments. However, the biochemical mechanism of AOM remains elusive. By explicitly resolving the observed spatial arrangement of methanotrophic archaea and sulfate reducing bacteria found in consortia mediating AOM, potential intermediates involved in the electron transfer between the methane oxidizing and sulfate reducing partners were investigated via a consortium-scale reaction transport model that integrates the effect of diffusional transport with thermodynamic and kinetic controls on microbial activity. Model simulations were used to assess the impact of poorly constrained microbial characteristics such as minimum energy requirements to sustain metabolism, substrate affinity and cell specific rates. The role of environmental conditions such as the influence of methane levels on the feasibility of H2, formate and acetate as intermediate species, and the impact of the abundance of intermediate species on pathway reversal was examined. The results show that higher production rates of intermediates via AOM lead to increased diffusive fluxes from the methane oxidizing archaea to sulfate reducing bacteria, but the build-up of the exchangeable species causes the energy yield of AOM to drop below that required for ATP production. Comparison to data from laboratory experiments shows that under the experimental conditions of Nauhaus et al. (2007, neither hydrogen nor formate is exchanged fast enough between the consortia partners to achieve measured rates of metabolic activity, but that acetate exchange might support rates that approach those observed.

  9. Effects of Fructooligosaccharides,compared with Direct-Fed Microbial Bacteria,and Zinc Bacitracin on Cecal Microbial Populations and Performance of Broilers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An experiment was conducted to determine the effects of dietary fructooligosaccharides(FOS),compared with direct-fed microbial bacteria (DFM),and zinc bacitracin ,on cecal microbial populations and performance of broiler Chickens. One hundred and ninety-two broilers (Avian) were randomly assigned to four groups,with four replicates of 12 birds each. The control group was fed with the basal diet,without any drug additive. FOS,DFM and zine bacitracin was respectively added to the basal diet at the level of 1.5% ,800 mg@kg-1 and 300 mg@ kg-1 to form the experimental diets. Body weight ,feed intake and feed efficiency were measured weekly. The feeding trial started at 1 d and ended at 21 d. At day 14 and day 21 ,four broilers per group were killed and cecum waa taken to determined microflors and pH. The results showed that dietary FOS increased bifidobactrial concentration by 1. 75-fold( P <0. 05) at 14 d of age and 1.45-fold( P <0. 05) at 21 d of age compared with control. FOS had no effect on concnetrations of E. coli and pH. There were no dietary effects of FOS,DFM,and zinc bacitracin on weight gain,feed intake,feed conversion( P >0. 05).

  10. Microbial influenced corrosion of stainless steels in natural waters: interest of an enzymatic approach

    International Nuclear Information System (INIS)

    The electrochemical behavior of stainless steels in natural waters has been characterized with the ennoblement of their free corrosion potential (Ecorr). This phenomenon is heavily related to the bio-film settlement on their surfaces. Many hypotheses have been suggested to make clear the bio-film action. These hypotheses can be classified in two categories: mechanisms due to the passive film change and mechanisms related to the bio-film species. In these hypotheses, the enzymatic catalysis can play an important role by shifting the cathodic process. The catalytic effect of the bio-film has been reported by numerous researchers; however the enzyme use in experiments remains rare. This can be explained by two principal reasons: 1- Corrosion tests with the use of enzymes may cause some experimental problems. These proteins are sensible and can be denatured in the corresponding conditions. 2- Scientists, in microbial influenced corrosion, did not characterize enzymes which may play a role in corrosion; however some bacteria related to corrosion had been already identified. The 'corrosion enzymes' notions are unaware. Thus, the enzymatic approach still little reported in the literature. The aim of this paper is to show the interest of such approach to describe mechanisms implicated in the electrochemical behavior of stainless steels in natural waters. (authors)

  11. Microbially influenced corrosion (MIC) of metal welds. Kinzoku yosetsubu no biseibutsu fushoku

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Y.; Matsuda, F. (Osaka Univ., Osaka (Japan). Welding Research Inst.)

    1993-06-20

    There is a microbially influenced corrosion (MIC) as one of the relations between the microorganism (bacteria) and the metal engineering. The corrosion accidents, which have been regarded as caused by MIC, have recently occurred in the petrochemical industry, gas industry, energy plant and so forth, and consequently the damage of structures has become to be the circumstances which were not negligible. It has been understood that the welds have a close relation out of the causes. The MIC advances with a very high speed under an existence of the microorganisms when the environmental conditions are satisfied, and even a value of about 0.57 nm/S (18 mm/year) is presumed in an example of SUS304 steel welds. In spite of defects, which were originally caused by the corrosion, there is a possibility that they were judged by mistake as caused by the weld imperfection. The MIC has a close relation with the plural disciplines such as the microbiology, material engineering, corrosion engineering, welding engineering, joining engineering and so forth. In this paper, the cases of MIC in the stainless steel welds, the kind of microorganisms which cause the MIC and the countermeasures agsinst them are outlined. 9 refs., 6 figs.

  12. A biogeographic distribution of magnetotactic bacteria influenced by salinity

    OpenAIRE

    Lin, Wei; Wang, Yinzhao; Li, Bi; Pan, Yongxin

    2011-01-01

    Magnetotactic bacteria (MTB), which synthesize intracellular ferromagnetic magnetite and/or greigite magnetosomes, have significant roles in global iron cycling in aquatic systems, as well as sedimentary magnetism. The occurrence of MTB has been reported in aquatic environments from freshwater to marine ecosystems; however, the distribution of MTB across heterogeneous habitats remains unclear. Here we examined the MTB communities from diverse habitats across northern and southern China, using...

  13. Influence of indoor microbial aerosol on the welfare of meat ducks.

    Science.gov (United States)

    Yu, G L; Wei, L M; Liu, Y Y; Liu, J Y; Wang, Y; Gao, J; Chai, T J; Cai, Y M

    2016-01-01

    The aim of the study was to evaluate the effects of microbial aerosols on ducks' welfare and provide information on which to establish microbial aerosol concentration standards for poultry. A total of 1800 1-d-old Cherry Valley ducks were randomly divided into 5 groups (A, B, C, D and E) with 360 ducks in each. To obtain objective data, each group had three replications. Different microbial aerosol concentrations in different groups were created by controlling ventilation and bedding cleaning frequency. Group A was the control group and hygienic conditions deteriorated progressively from group B to E. A 6-stage Andersen impactor was used to detect the aerosol concentration of aerobes, fungi, gram-negative bacteria and an AGI-30 microbial air sampler detected endotoxins. Physiological stress was evaluated in the ducks by adrenocorticotropic hormone (ACTH) values in serum. To assess the effects of bioaerosol factors, welfare indicators including fluctuating asymmetry (FA), appearance and gait as well as the Lactobacillus caecal concentration were evaluated. The data showed group D had already reached the highest limit of concentration of airborne aerobic bacteria, airborne fungi, airborne gram-negative bacteria and airborne endotoxin. The ducks in this group had significantly increased serum ACTH values and significantly decreased caecal lactobacilli concentration. Furthermore, appearance and gait scores, wing length and overall FA and caecal Lactobacillus concentration in this group were significantly increased at 6 and 8 weeks of age. In conclusion, high concentrations of microbial aerosol adversely affected the welfare of meat ducks. The microbial aerosol values in group D suggest a preliminary upper limit concentration of bioaerosols in ambient air for healthy meat ducks. PMID:26594822

  14. Bacteria diversity and microbial biomass in forest, pasture and fallow soils in the southwestern Amazon basin Diversidade de bacteria e biomassa microbiana em solos sob floresta, pastagem e capoeira no sudoeste da Amazônia

    Directory of Open Access Journals (Sweden)

    Karina Cenciani

    2009-08-01

    Full Text Available It is well-known that Amazon tropical forest soils contain high microbial biodiversity. However, anthropogenic actions of slash and burn, mainly for pasture establishment, induce profound changes in the well-balanced biogeochemical cycles. After a few years the grass yield usually declines, the pasture is abandoned and is transformed into a secondary vegetation called "capoeira" or fallow. The aim of this study was to examine how the clearing of Amazon rainforest for pasture affects: (1 the diversity of the Bacteria domain evaluated by Polymerase Chain Reaction and Denaturing Gradient Gel Electrophoresis (PCR-DGGE, (2 microbial biomass and some soil chemical properties (pH, moisture, P, K, Ca, Mg, Al, H + Al, and BS, and (3 the influence of environmental variables on the genetic structure of bacterial community. In the pasture soil, total carbon (C was between 30 to 42 % higher than in the fallow, and almost 47 % higher than in the forest soil over a year. The same pattern was observed for N. Microbial biomass in the pasture was about 38 and 26 % higher than at fallow and forest sites, respectively, in the rainy season. DGGE profiling revealed a lower number of bands per area in the dry season, but differences in the structure of bacterial communities among sites were better defined than in the wet season. The bacterial DNA fingerprints in the forest were stronger related to Al content and the Cmic:Ctot and Nmic:Ntot ratios. For pasture and fallow sites, the structure of the Bacteria domain was more associated with pH, sum of bases, moisture, total C and N and the microbial biomass. In general microbial biomass in the soils was influenced by total C and N, which were associated with the Bacteria domain, since the bacterial community is a component and active fraction of the microbial biomass. Results show that the genetic composition of bacterial communities in Amazonian soils changed along the sequence forest-pasture-fallow.Os solos da floresta

  15. Autotrophic nitrogen assimilation and carbon capture for microbial protein production by a novel enrichment of hydrogen-oxidizing bacteria.

    Science.gov (United States)

    Matassa, Silvio; Verstraete, Willy; Pikaar, Ilje; Boon, Nico

    2016-09-15

    Domestic used water treatment systems are currently predominantly based on conventional resource inefficient treatment processes. While resource recovery is gaining momentum it lacks high value end-products which can be efficiently marketed. Microbial protein production offers a valid and promising alternative by upgrading low value recovered resources into high quality feed and also food. In the present study, we evaluated the potential of hydrogen-oxidizing bacteria to upgrade ammonium and carbon dioxide under autotrophic growth conditions. The enrichment of a generic microbial community and the implementation of different culture conditions (sequenced batch resp. continuous reactor) revealed surprising features. At low selection pressure (i.e. under sequenced batch culture at high solid retention time), a very diverse microbiome with an important presence of predatory Bdellovibrio spp. was observed. The microbial culture which evolved under high rate selection pressure (i.e. dilution rate D = 0.1 h(-1)) under continuous reactor conditions was dominated by Sulfuricurvum spp. and a highly stable and efficient process in terms of N and C uptake, biomass yield and volumetric productivity was attained. Under continuous culture conditions the maximum yield obtained was 0.29 g cell dry weight per gram chemical oxygen demand equivalent of hydrogen, whereas the maximum volumetric loading rate peaked 0.41 g cell dry weight per litre per hour at a protein content of 71%. Finally, the microbial protein produced was of high nutritive quality in terms of essential amino acids content and can be a suitable substitute for conventional feed sources such as fishmeal or soybean meal. PMID:27262118

  16. Autotrophic nitrogen assimilation and carbon capture for microbial protein production by a novel enrichment of hydrogen-oxidizing bacteria.

    Science.gov (United States)

    Matassa, Silvio; Verstraete, Willy; Pikaar, Ilje; Boon, Nico

    2016-09-15

    Domestic used water treatment systems are currently predominantly based on conventional resource inefficient treatment processes. While resource recovery is gaining momentum it lacks high value end-products which can be efficiently marketed. Microbial protein production offers a valid and promising alternative by upgrading low value recovered resources into high quality feed and also food. In the present study, we evaluated the potential of hydrogen-oxidizing bacteria to upgrade ammonium and carbon dioxide under autotrophic growth conditions. The enrichment of a generic microbial community and the implementation of different culture conditions (sequenced batch resp. continuous reactor) revealed surprising features. At low selection pressure (i.e. under sequenced batch culture at high solid retention time), a very diverse microbiome with an important presence of predatory Bdellovibrio spp. was observed. The microbial culture which evolved under high rate selection pressure (i.e. dilution rate D = 0.1 h(-1)) under continuous reactor conditions was dominated by Sulfuricurvum spp. and a highly stable and efficient process in terms of N and C uptake, biomass yield and volumetric productivity was attained. Under continuous culture conditions the maximum yield obtained was 0.29 g cell dry weight per gram chemical oxygen demand equivalent of hydrogen, whereas the maximum volumetric loading rate peaked 0.41 g cell dry weight per litre per hour at a protein content of 71%. Finally, the microbial protein produced was of high nutritive quality in terms of essential amino acids content and can be a suitable substitute for conventional feed sources such as fishmeal or soybean meal.

  17. Treatment of gaseous toluene in three biofilters inoculated with fungi/bacteria: Microbial analysis, performance and starvation response.

    Science.gov (United States)

    Cheng, Zhuowei; Lu, Lichao; Kennes, Christian; Yu, Jianming; Chen, Jianmeng

    2016-02-13

    Bacteria and fungi are often utilized for the biodegradation of organic pollutants. This study compared fungal and/or bacterial biofiltration in treating toluene under both steady and unsteady states. Fungal biofilter (F-BF) removed less toluene than both bacterial biofilters (B-BF) and fungal & bacterial biofilters (F&B-BF) (60% vs >90%). The mineralization ratio was also lower in F-BF-levels were 2/3 and 1/2 of those values obtained by the other biofilters. Microbial analysis showed that richer communities were present in B-BF and F&B-BF, and that the Hypocreales genus which Trichoderma viride belongs to was much better represented in F&B-BF. The F&B-BF also supported enhanced robustness after 15-day starvation episodes; 1 day later the performance recovered to 80% of the original removal level. The combination of bacteria and fungi makes biofiltration a good option for VOC treatment including better removal and performance stability versus individual biofilters (bacteria or fungi dominated).

  18. Influences of graphene on microbial community and antibiotic resistance genes in mouse gut as determined by high-throughput sequencing.

    Science.gov (United States)

    Xie, Yongchao; Wu, Bing; Zhang, Xu-Xiang; Yin, Jinbao; Mao, Liang; Hu, Maojie

    2016-02-01

    Graphene is a promising candidate as an antibacterial material owning to its bacterial toxicity. However, little information on influence of graphene on gut microbiota is available. In this study, mice were exposed to graphene for 4 weeks, and high-throughput sequencing was applied to characterize the changes in microbial community and antibiotic resistance genes (ARGs) in mouse gut. The results showed that graphene exposure increased biodiversity of gut microbiota, and changed their community. The 1 μg/d graphene exposure had higher influences on the gut microbiota than 10 μg/d and 100 μg/d graphene exposures, which might be due to higher aggregation of high-level graphene. The influence of graphene on gut microbiota might attribute to that graphene could induce oxidative stress and damage of cell membrane integrity. The results were verified by the increase of ratio of Gram-negative bacteria. Outer membrane of Gram-negative bacteria could reduce the membrane damage induced by graphene and make them more tolerance to graphene. Further, we found that graphene exposure significantly increased the abundance and types of ARGs, indicating a potential health risk of graphene. This study firstly provides new insight to the health effects of graphene on gut microbiota.

  19. Tree Species Composition Influences Enzyme Activities and Microbial Biomass in the Rhizosphere: A Rhizobox Approach

    OpenAIRE

    Shengzuo Fang; Dong Liu; Ye Tian; Shiping Deng; Xulan Shang

    2013-01-01

    Monoculture causes nutrient losses and leads to declines in soil fertility and biomass production over successive cultivation. The rhizosphere, a zone of usually high microbial activities and clearly distinct from bulk soil, is defined as the volume of soil around living roots and influenced by root activities. Here we investigated enzyme activities and microbial biomass in the rhizosphere under different tree compositions. Six treatments with poplar, willow, and alder mono- or mixed seedling...

  20. Ancient bacteria in permafrost soils fact or artefact? Considerations in recovering microbial DNA from geological ancient settings

    Science.gov (United States)

    Willerslev, E.

    2003-04-01

    Several recent reports claim that prokaryotic genetic sequences or viable cultures can survive for millions of years in geological settings. If substantiated, these findings could fundamentally alter views about bacterial physiology, ecology and evolution. However, both the culturing of microbes and the amplification of ancient DNA molecules from fossil remains are beset with difficulties. First, theoretical and empirical studies have shown that small DNA fragments (100 200 bp) do not survive in the geosphere for more than 104 years in temperate environments and 105 years in colder ones due to hydrolytic and oxidative damage. Therefore, the revivals of dormant bacteria with no active DNA repair from remains hundreds of thousands to millions of years old is, from a theoretical point, expected to be difficult, if not impossible. Second, the no specificity of the media used to culture micro organisms, as well as the great sensitivity of PCR, makes the risk of contamination with contemporary ubiquitous microbial cells and exogenous DNA molecules extremely high. Contamination poses risks at all stages of sample processing (e.g.) within the samples themselves, in the chemical reagents, on laboratory disposables or through the air. The high risk of contamination strongly suggests the need for standardized procedures within the field such as independent replication of results. This criterion of authenticity has not yet been full field in any of the studies claiming million year old microbial cultures or DNA. In order to tests the long-term survival of ancient bacteria DNA a study on permafrost was conducted using ancient DNA precautions, controls and criteria. Permafrost must be considered among the most promising environments for long term DNA survival due to its constant low temperatures (-10C to 12C Siberian or 20C Antarctica) and high cell numbers (107). We found that bacteria DNA could reproducibly be obtained from samples dated up to 300-400,000 years B.P. but not

  1. The influence of microbial ecology of drinking water biofilms on their resistance to disinfection

    OpenAIRE

    Simões, Lúcia C

    2010-01-01

    The knowledge of the role of microbial ecology of drinking water (DW) biofilms on disinfection might help to improve our understanding of their resistance mechanisms and allow the development of effective strategies to apply in drinking water distribution systems (DWDS). In this study six opportunistic bacteria (Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp.) isolated from a DWDS were used...

  2. Influence of Organic Manures (Biofertilizers on Soil Microbial Population in the Rhizosphere of Mulberry (Morus Indica L.

    Directory of Open Access Journals (Sweden)

    L. Christilda Louis Mary

    2015-03-01

    Full Text Available The effect of different kinds of organic manures on soil microbial population and mulberry production was assessed. A field experiment wascarried out at Periyar EVR College, Tamil Nadu, India in basic soil to study the influence of organic manures on soil bacterial population andmulberry production. The 4 groups of mulberry plants of MR2 variety were biofertilized with FYM, Azospirillum, Phosphobacteria andVermicompost respectively. The biofertilizers lodged bacteria on the rhizosphere of mulberry plants. When the root microorganism areanalyzed Farm yard manure biofertilized mulberry plant root tips had Gluconacobacter diazotrophicus, Bacillus pumilus, Pseudomonas putida,Bacillus coagulans, Bacillus sonorensis, Azotobacter chrococcum; Azospirillum biofertilized mulberry plants root tips had Bacillus coaculans,Azotobactor chrococcum, Azotobactor vinelandii, Bacillus subtilis and Azospirillum brasilense. Phosphobacteria biofertilized mulberry plantroot tips had Pseudomonas putida, Bacillus stearothermophilus, Brevibacillus borslelansis and Streptomycies thermonitrificans andvermicompost biofertilized mulberry plant root tips had lodged bacterias like Bacillus megaterium, Bacillus subtilis, Gluconacobacterdiazotrophicus, Pseudomonas putida, Azotobacter chrococcum, Azotobacter vinelandi, Bacillus stearothermophilus, Brevibacillus borslelansisand Bacillus sonorensis. Microbiology work reveals luxuriant growth of bacteria in all the biofertizer treated rhizosphere in the order FYM

  3. Using a Microbial Physiologic and Genetic Approach to Investigate How Bacteria Sense Physical Stimuli

    Science.gov (United States)

    Mussi, María Alejandra; Actis, Luis A.; de Mendoza, Diego; Cybulski, Larisa E.

    2014-01-01

    A laboratory exercise was designed to illustrate how physical stimuli such as temperature and light are sensed and processed by bacteria to elaborate adaptive responses. In particular, we use the well-characterized Des pathway of "Bacillus subtilis" to show that temperature modulates gene expression, resulting ultimately in modification…

  4. Microbial communication, cooperation and cheating: quorum sensing drives the evolution of cooperation in bacteria

    NARCIS (Netherlands)

    Czaran, T.L.; Hoekstra, R.F.

    2009-01-01

    An increasing body of empirical evidence suggests that cooperation among clone-mates is common in bacteria. Bacterial cooperation may take the form of the excretion of ‘‘public goods’’: exoproducts such as virulence factors, exoenzymes or components of the matrix in biofilms, to yield significant be

  5. Seaweed-microbial interactions: key functions of seaweed-associated bacteria.

    Science.gov (United States)

    Singh, Ravindra Pal; Reddy, C R K

    2014-05-01

    Seaweed-associated bacteria play a crucial role in morphogenesis and growth of seaweeds (macroalgae) in direct and/or indirect ways. Bacterial communities belonging to the phyla Proteobacteria and Firmicutes are generally the most abundant on seaweed surfaces. Associated bacterial communities produce plant growth-promoting substances, quorum sensing signalling molecules, bioactive compounds and other effective molecules that are responsible for normal morphology, development and growth of seaweeds. Also, bioactive molecules of associated bacteria determine the presence of other bacterial strains on seaweeds and protect the host from harmful entities present in the pelagic realm. The ecological functions of cross-domain signalling between seaweeds and bacteria have been reported as liberation of carpospores in the red seaweeds and settlement of zoospores in the green seaweeds. In the present review, the role of extracellular polymeric substances in growth and settlement of seaweeds spores is also highlighted. To elucidate the functional roles of associated bacteria and the molecular mechanisms underlying reported ecological phenomena in seaweeds requires a combined ecological, microbiological and biochemical approach. PMID:24512602

  6. Reprogrammable microbial cell-based therapeutics against antibiotic-resistant bacteria.

    Science.gov (United States)

    Hwang, In Young; Koh, Elvin; Kim, Hye Rim; Yew, Wen Shan; Chang, Matthew Wook

    2016-07-01

    The discovery of antimicrobial drugs and their subsequent use has offered an effective treatment option for bacterial infections, reducing morbidity and mortality over the past 60 years. However, the indiscriminate use of antimicrobials in the clinical, community and agricultural settings has resulted in selection for multidrug-resistant bacteria, which has led to the prediction of possible re-entrance to the pre-antibiotic era. The situation is further exacerbated by significantly reduced antimicrobial drug discovery efforts by large pharmaceutical companies, resulting in a steady decline in the number of new antimicrobial agents brought to the market in the past several decades. Consequently, there is a pressing need for new antimicrobial therapies that can be readily designed and implemented. Recently, it has become clear that the administration of broad-spectrum antibiotics can lead to collateral damage to the human commensal microbiota, which plays several key roles in host health. Advances in genetic engineering have opened the possibility of reprogramming commensal bacteria that are in symbiotic existence throughout the human body to implement antimicrobial drugs with high versatility and efficacy against pathogenic bacteria. In this review, we discuss recent advances and potentialities of engineered bacteria in providing a novel antimicrobial strategy against antibiotic resistance. PMID:27449598

  7. Microbial Corrosion of API 5L X-70 Carbon Steel by ATCC 7757 and Consortium of Sulfate-Reducing Bacteria

    OpenAIRE

    2014-01-01

    Various cases of accidents involving microbiology influenced corrosion (MIC) were reported by the oil and gas industry. Sulfate reducing bacteria (SRB) have always been linked to MIC mechanisms as one of the major causes of localized corrosion problems. In this study, SRB colonies were isolated from the soil in suspected areas near the natural gas transmission pipeline in Malaysia. The effects of ATCC 7757 and consortium of isolated SRB upon corrosion on API 5L X-70 carbon steel coupon were i...

  8. Enhancement of microbial quality and inactivation of pathogenic bacteria by gamma irradiation of ready-to-cook Iranian barbecued chicken

    Science.gov (United States)

    Fallah, Aziz A.; Siavash Saei-Dehkordi, S.; Rahnama, Mohammad

    2010-10-01

    Ready-to-cook Iranian barbecued chicken consists of cubed chicken breast, lemon juice, salt, red pepper, onion, saffron and vegetable oil with an overall pH value of about 5.5. This product is sometimes consumed under-cooked, hence it may pose health hazards to consumers when contaminated with food-borne pathogens. In this study, the effect of gamma irradiation (0, 1.5, 3 and 4.5 kGy) on the microbial quality of ready-to-cook (RTC) barbecued chicken samples stored at 4 °C for 15 days was investigated. Moreover, the effectiveness of irradiation for inactivating Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella typhimurium inoculated into the samples was also studied. Irradiation of the samples resulted in dose dependent reduction in counts of aerobic mesophilic bacteria, yeasts and molds, Enterobacteriaceae and lactic acid bacteria. Among the microbial flora, yeasts and molds and Enterobacteriaceae were more sensitive to irradiation and got completely eliminated at dose of 3 kGy. D10 values of L. monocytogenes, E. coli O157:H7 and S. typhimurium inoculated into the samples were 0.680, 0.397 and 0.601 kGy, respectively. An irradiation dose of 3 kGy reduced the counts of E. coli O157:H7 to an undetectable level in RTC barbecued chicken but was ineffective on elimination of L. monocytogenes and S. typhimurium. However, none of the food-borne pathogens were detected in the samples irradiated at 4.5 kGy. This study showed that irradiation had no undesirable effects on the initial sensory attributes of barbecued chicken. At the end of the storage period, irradiated samples were more acceptable compared to non-irradiated ones.

  9. Enhancement of microbial quality and inactivation of pathogenic bacteria by gamma irradiation of ready-to-cook Iranian barbecued chicken

    International Nuclear Information System (INIS)

    Ready-to-cook Iranian barbecued chicken consists of cubed chicken breast, lemon juice, salt, red pepper, onion, saffron and vegetable oil with an overall pH value of about 5.5. This product is sometimes consumed under-cooked, hence it may pose health hazards to consumers when contaminated with food-borne pathogens. In this study, the effect of gamma irradiation (0, 1.5, 3 and 4.5 kGy) on the microbial quality of ready-to-cook (RTC) barbecued chicken samples stored at 4 oC for 15 days was investigated. Moreover, the effectiveness of irradiation for inactivating Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella typhimurium inoculated into the samples was also studied. Irradiation of the samples resulted in dose dependent reduction in counts of aerobic mesophilic bacteria, yeasts and molds, Enterobacteriaceae and lactic acid bacteria. Among the microbial flora, yeasts and molds and Enterobacteriaceae were more sensitive to irradiation and got completely eliminated at dose of 3 kGy. D10 values of L. monocytogenes, E. coli O157:H7 and S. typhimurium inoculated into the samples were 0.680, 0.397 and 0.601 kGy, respectively. An irradiation dose of 3 kGy reduced the counts of E. coli O157:H7 to an undetectable level in RTC barbecued chicken but was ineffective on elimination of L. monocytogenes and S. typhimurium. However, none of the food-borne pathogens were detected in the samples irradiated at 4.5 kGy. This study showed that irradiation had no undesirable effects on the initial sensory attributes of barbecued chicken. At the end of the storage period, irradiated samples were more acceptable compared to non-irradiated ones.

  10. Enhancement of microbial quality and inactivation of pathogenic bacteria by gamma irradiation of ready-to-cook Iranian barbecued chicken

    Energy Technology Data Exchange (ETDEWEB)

    Fallah, Aziz A., E-mail: a_a_falah@yahoo.co [Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Shahre-Kord University, Shahre-Kord 34141 (Iran, Islamic Republic of); Research Institute of Zoonotic Diseases, Shahre-Kord University, Shahre-Kord 34141 (Iran, Islamic Republic of); Siavash Saei-Dehkordi, S. [Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Shahre-Kord University, Shahre-Kord 34141 (Iran, Islamic Republic of); Research Institute of Zoonotic Diseases, Shahre-Kord University, Shahre-Kord 34141 (Iran, Islamic Republic of); Rahnama, Mohammad [Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, University of Zabol, Zabol 98615 (Iran, Islamic Republic of)

    2010-10-15

    Ready-to-cook Iranian barbecued chicken consists of cubed chicken breast, lemon juice, salt, red pepper, onion, saffron and vegetable oil with an overall pH value of about 5.5. This product is sometimes consumed under-cooked, hence it may pose health hazards to consumers when contaminated with food-borne pathogens. In this study, the effect of gamma irradiation (0, 1.5, 3 and 4.5 kGy) on the microbial quality of ready-to-cook (RTC) barbecued chicken samples stored at 4 {sup o}C for 15 days was investigated. Moreover, the effectiveness of irradiation for inactivating Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella typhimurium inoculated into the samples was also studied. Irradiation of the samples resulted in dose dependent reduction in counts of aerobic mesophilic bacteria, yeasts and molds, Enterobacteriaceae and lactic acid bacteria. Among the microbial flora, yeasts and molds and Enterobacteriaceae were more sensitive to irradiation and got completely eliminated at dose of 3 kGy. D{sub 10} values of L. monocytogenes, E. coli O157:H7 and S. typhimurium inoculated into the samples were 0.680, 0.397 and 0.601 kGy, respectively. An irradiation dose of 3 kGy reduced the counts of E. coli O157:H7 to an undetectable level in RTC barbecued chicken but was ineffective on elimination of L. monocytogenes and S. typhimurium. However, none of the food-borne pathogens were detected in the samples irradiated at 4.5 kGy. This study showed that irradiation had no undesirable effects on the initial sensory attributes of barbecued chicken. At the end of the storage period, irradiated samples were more acceptable compared to non-irradiated ones.

  11. Influence of Surface Roughness of Stainless steel on Microbial Adhesion

    DEFF Research Database (Denmark)

    Bagge, D.; Hilbert, Lisbeth Rischel; Gram, L.

    2002-01-01

    Bacterial adhesion and biofilm formation is of growing interest in the food processing industry where bacteria can survive on surfaces and resist cleaning and disinfection. The condition of the surfaces (eg lack of cracks) and their general roughness is assumed to be important for the hygienic st...

  12. Influence of coral and algal exudates on microbially mediated reef metabolism

    Directory of Open Access Journals (Sweden)

    Andreas F. Haas

    2013-07-01

    Full Text Available Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC exudate release by the dominant benthic primary producers (calcifying and non-calcifying macroalgae, turf-algae and corals on reefs of Mo‘orea French Polynesia. Subsequently, we examined planktonic and benthic microbial community response to these dissolved exudates by measuring bacterial growth rates and oxygen and DOC fluxes in dark and daylight incubation experiments. All benthic primary producers exuded significant quantities of DOC (roughly 10% of their daily fixed carbon into the surrounding water over a diurnal cycle. The microbial community responses were dependent upon the source of the exudates and whether the inoculum of microbes included planktonic or planktonic plus benthic communities. The planktonic and benthic microbial communities in the unamended control treatments exhibited opposing influences on DO concentration where respiration dominated in treatments comprised solely of plankton and autotrophy dominated in treatments with benthic plus plankon microbial communities. Coral exudates (and associated inorganic nutrients caused a shift towards a net autotrophic microbial metabolism by increasing the net production of oxygen by the benthic and decreasing the net consumption of oxygen by the planktonic microbial community. In contrast, the addition of algal exudates decreased the net primary production by the benthic communities and increased the net consumption of oxygen by the planktonic microbial community thereby resulting in a shift towards net heterotrophic community metabolism. When scaled up to the reef habitat, exudate-induced effects on microbial respiration did not outweigh the high oxygen production rates of benthic algae, such that reef areas dominated with

  13. Microbial oil-degradation under mild hydrostatic pressure (10 MPa): which pathways are impacted in piezosensitive hydrocarbonoclastic bacteria?

    Science.gov (United States)

    Scoma, Alberto; Barbato, Marta; Hernandez-Sanabria, Emma; Mapelli, Francesca; Daffonchio, Daniele; Borin, Sara; Boon, Nico

    2016-01-01

    Oil spills represent an overwhelming carbon input to the marine environment that immediately impacts the sea surface ecosystem. Microbial communities degrading the oil fraction that eventually sinks to the seafloor must also deal with hydrostatic pressure, which linearly increases with depth. Piezosensitive hydrocarbonoclastic bacteria are ideal candidates to elucidate impaired pathways following oil spills at low depth. In the present paper, we tested two strains of the ubiquitous Alcanivorax genus, namely A. jadensis KS_339 and A. dieselolei KS_293, which is known to rapidly grow after oil spills. Strains were subjected to atmospheric and mild pressure (0.1, 5 and 10 MPa, corresponding to a depth of 0, 500 and 1000 m, respectively) providing n-dodecane as sole carbon source. Pressures equal to 5 and 10 MPa significantly lowered growth yields of both strains. However, in strain KS_293 grown at 10 MPa CO2 production per cell was not affected, cell integrity was preserved and PO4(3-) uptake increased. Analysis of its transcriptome revealed that 95% of its genes were downregulated. Increased transcription involved protein synthesis, energy generation and respiration pathways. Interplay between these factors may play a key role in shaping the structure of microbial communities developed after oil spills at low depth and limit their bioremediation potential. PMID:27020120

  14. Microbial oil-degradation under mild hydrostatic pressure (10 MPa): which pathways are impacted in piezosensitive hydrocarbonoclastic bacteria?

    Science.gov (United States)

    Scoma, Alberto; Barbato, Marta; Hernandez-Sanabria, Emma; Mapelli, Francesca; Daffonchio, Daniele; Borin, Sara; Boon, Nico

    2016-03-01

    Oil spills represent an overwhelming carbon input to the marine environment that immediately impacts the sea surface ecosystem. Microbial communities degrading the oil fraction that eventually sinks to the seafloor must also deal with hydrostatic pressure, which linearly increases with depth. Piezosensitive hydrocarbonoclastic bacteria are ideal candidates to elucidate impaired pathways following oil spills at low depth. In the present paper, we tested two strains of the ubiquitous Alcanivorax genus, namely A. jadensis KS_339 and A. dieselolei KS_293, which is known to rapidly grow after oil spills. Strains were subjected to atmospheric and mild pressure (0.1, 5 and 10 MPa, corresponding to a depth of 0, 500 and 1000 m, respectively) providing n-dodecane as sole carbon source. Pressures equal to 5 and 10 MPa significantly lowered growth yields of both strains. However, in strain KS_293 grown at 10 MPa CO2 production per cell was not affected, cell integrity was preserved and PO43‑ uptake increased. Analysis of its transcriptome revealed that 95% of its genes were downregulated. Increased transcription involved protein synthesis, energy generation and respiration pathways. Interplay between these factors may play a key role in shaping the structure of microbial communities developed after oil spills at low depth and limit their bioremediation potential.

  15. Microbial oil-degradation under mild hydrostatic pressure (10 MPa): which pathways are impacted in piezosensitive hydrocarbonoclastic bacteria?

    KAUST Repository

    Scoma, Alberto

    2016-03-29

    Oil spills represent an overwhelming carbon input to the marine environment that immediately impacts the sea surface ecosystem. Microbial communities degrading the oil fraction that eventually sinks to the seafloor must also deal with hydrostatic pressure, which linearly increases with depth. Piezosensitive hydrocarbonoclastic bacteria are ideal candidates to elucidate impaired pathways following oil spills at low depth. In the present paper, we tested two strains of the ubiquitous Alcanivorax genus, namely A. jadensis KS_339 and A. dieselolei KS_293, which is known to rapidly grow after oil spills. Strains were subjected to atmospheric and mild pressure (0.1, 5 and 10 MPa, corresponding to a depth of 0, 500 and 1000 m, respectively) providing n-dodecane as sole carbon source. Pressures equal to 5 and 10 MPa significantly lowered growth yields of both strains. However, in strain KS_293 grown at 10 MPa CO2 production per cell was not affected, cell integrity was preserved and PO43− uptake increased. Analysis of its transcriptome revealed that 95% of its genes were downregulated. Increased transcription involved protein synthesis, energy generation and respiration pathways. Interplay between these factors may play a key role in shaping the structure of microbial communities developed after oil spills at low depth and limit their bioremediation potential.

  16. Anodic biofilms in microbial fuel cells harbor low numbers of higher-power-producing bacteria than abundant genera

    KAUST Repository

    Kiely, Patrick D.

    2010-07-15

    Microbial fuel cell (MFC) anode communities often reveal just a few genera, but it is not known to what extent less abundant bacteria could be important for improving performance. We examined the microbial community in an MFC fed with formic acid for more than 1 year and determined using 16S rRNA gene cloning and fluorescent in situ hybridization that members of the Paracoccus genus comprised most (~30%) of the anode community. A Paracoccus isolate obtained from this biofilm (Paracoccus denitrificans strain PS-1) produced only 5.6 mW/m 2, whereas the original mixed culture produced up to 10 mW/m 2. Despite the absence of any Shewanella species in the clone library, we isolated a strain of Shewanella putrefaciens (strain PS-2) from the same biofilm capable of producing a higher-power density (17.4 mW/m2) than the mixed culture, although voltage generation was variable. Our results suggest that the numerical abundance of microorganisms in biofilms cannot be assumed a priori to correlate to capacities of these predominant species for high-power production. Detailed screening of bacterial biofilms may therefore be needed to identify important strains capable of high-power generation for specific substrates. © 2010 Springer-Verlag.

  17. Screening of bacteria for self-healing of concrete cracks and optimization of the microbial calcium precipitation process.

    Science.gov (United States)

    Zhang, J L; Wu, R S; Li, Y M; Zhong, J Y; Deng, X; Liu, B; Han, N X; Xing, F

    2016-08-01

    A novel high-throughput strategy was developed to determine the calcium precipitation activity (CPA) of mineralization bacteria used for self-healing of concrete cracks. A bacterial strain designated as H4 with the highest CPA of 94.8 % was screened and identified as a Bacillus species based on 16S rDNA sequence and phylogenetic tree analysis. Furthermore, the effects of certain influential factors on the microbial calcium precipitation process of H4 were evaluated. The results showed that lactate and nitrate are the best carbon and nitrogen sources, with optimal concentrations of approximately 25 and 18 mM, respectively. The H4 strain is able to maintain a high CPA in the pH range of 9.5-11.0, and a suitable initial spore concentration is 4.0 × 10(7) spores/ml. Moreover, an ambient Ca(2+) concentration greater than 60 mM resulted in a serious adverse impact not only on the CPA but also on the growth of H4, suggesting that the maintenance of the Ca(2+) concentration at a low level is necessary for microbial self-healing of concrete cracks. PMID:26883348

  18. Screening of bacteria for self-healing of concrete cracks and optimization of the microbial calcium precipitation process.

    Science.gov (United States)

    Zhang, J L; Wu, R S; Li, Y M; Zhong, J Y; Deng, X; Liu, B; Han, N X; Xing, F

    2016-08-01

    A novel high-throughput strategy was developed to determine the calcium precipitation activity (CPA) of mineralization bacteria used for self-healing of concrete cracks. A bacterial strain designated as H4 with the highest CPA of 94.8 % was screened and identified as a Bacillus species based on 16S rDNA sequence and phylogenetic tree analysis. Furthermore, the effects of certain influential factors on the microbial calcium precipitation process of H4 were evaluated. The results showed that lactate and nitrate are the best carbon and nitrogen sources, with optimal concentrations of approximately 25 and 18 mM, respectively. The H4 strain is able to maintain a high CPA in the pH range of 9.5-11.0, and a suitable initial spore concentration is 4.0 × 10(7) spores/ml. Moreover, an ambient Ca(2+) concentration greater than 60 mM resulted in a serious adverse impact not only on the CPA but also on the growth of H4, suggesting that the maintenance of the Ca(2+) concentration at a low level is necessary for microbial self-healing of concrete cracks.

  19. Characterizing relationships among fecal indicator bacteria, microbial source tracking markers, and associated waterborne pathogen occurrence in stream water and sediments in a mixed land use watershed

    Science.gov (United States)

    Bed sediments of streams and rivers may store high concentrations of fecal indicator bacteria (FIB) and pathogens. Due to resuspension events, these contaminants can be mobilized into the water column and affect overall water quality. Other bacterial indicators such as microbial ...

  20. Microbially influenced corrosion of zinc and aluminium - Two-year subjection to influence of Aspergillus niger

    Energy Technology Data Exchange (ETDEWEB)

    Juzeliunas, Eimutis [Institute of Chemistry, A.Gostauto 9, 01108 Vilnius (Lithuania)], E-mail: ejuzel@ktl.mii.lt; Ramanauskas, Rimantas; Lugauskas, Albinas; Leinartas, Konstantinas; Samuleviciene, Meilute; Sudavicius, Aloyzas; Juskenas, Remigijus [Institute of Chemistry, A.Gostauto 9, 01108 Vilnius (Lithuania)

    2007-11-15

    Aspergillus niger. Tiegh., a filamentous ascomycete fungus, was isolated from the metal samples exposed to marine, rural and urban sites in Lithuania. Al and Zn samples were subjected to two-year influence of A. niger under laboratory conditions in humid atmosphere. Electrochemical impedance spectroscopy (EIS) ascertained microbially influenced corrosion acceleration (MICA) of Zn and inhibition (MICI) of Al. EIS data indicated a two-layer structure of corrosion products on Zn. The microorganisms reduced the thickness of the inner layer, whose passivating capacity was much higher when compared to that of the outer layer. An increase in aluminium oxide layer resistance but decrease in the layer thickness implied that MICI affected primarily the sites of localized corrosion of Al (pores, micro-cracks, etc.). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies indicated that bioproducts (i.e. organic acids) did not form crystalline phases with corrosion products of zinc. The study suggested a hypothesis that microorganisms could be used as corrosion protectors instead of toxic chemicals, application of which tends to be increasingly restricted.

  1. Microbial enhanced oil recovery—a modeling study of the potential of spore-forming bacteria

    DEFF Research Database (Denmark)

    Nielsen, Sidsel Marie; Nesterov, Igor; Shapiro, Alexander

    2016-01-01

    resulted in the following conclusions. In order to obtain sufficient local concentrations of surfactant, substantial amounts of substrate should be supplied; however, massive growth of bacteria increases the risk for clogging at the well inlet areas, causing injectivity loss. In such areas, starvation may....... One of the ways of bacterial survival and propagation under harsh reservoir conditions is formation of spores. A model has been developed that accounts for bacterial growth, substrate consumption, surfactant production, attachment/filtering out, sporulation, and reactivation. Application of spore......-forming bacteria is an advantageous novelty of the present approach. The mathematical setup is a set of 1D transport equations involving reactions and attachment. Characteristic sigmoidal curves are used to describe sporulation and reactivation in response to substrate concentrations. The role of surfactant...

  2. Changes in the microbial community structure of bacteria, archaea and fungi in response to elevated CO(2) and warming in an Australian native grassland soil.

    Science.gov (United States)

    Hayden, Helen L; Mele, Pauline M; Bougoure, Damian S; Allan, Claire Y; Norng, Sorn; Piceno, Yvette M; Brodie, Eoin L; Desantis, Todd Z; Andersen, Gary L; Williams, Amity L; Hovenden, Mark J

    2012-12-01

    The microbial community structure of bacteria, archaea and fungi is described in an Australian native grassland soil after more than 5 years exposure to different atmospheric CO2 concentrations ([CO2]) (ambient, +550 ppm) and temperatures (ambient, + 2°C) under different plant functional types (C3 and C4 grasses) and at two soil depths (0-5 cm and 5-10 cm). Archaeal community diversity was influenced by elevated [CO2], while under warming archaeal 16S rRNA gene copy numbers increased for C4 plant Themeda triandra and decreased for the C3 plant community (P < 0.05). Fungal community diversity resulted in three groups based upon elevated [CO2], elevated [CO2] plus warming and ambient [CO2]. Overall bacterial community diversity was influenced primarily by depth. Specific bacterial taxa changed in richness and relative abundance in response to climate change factors when assessed by a high-resolution 16S rRNA microarray (PhyloChip). Operational taxonomic unit signal intensities increased under elevated [CO2] for both Firmicutes and Bacteroidetes, and increased under warming for Actinobacteria and Alphaproteobacteria. For the interaction of elevated [CO2] and warming there were 103 significant operational taxonomic units (P < 0.01) representing 15 phyla and 30 classes. The majority of these operational taxonomic units increased in abundance for elevated [CO2] plus warming plots, while abundance declined in warmed or elevated [CO2] plots. Bacterial abundance (16S rRNA gene copy number) was significantly different for the interaction of elevated [CO2] and depth (P < 0.05) with decreased abundance under elevated [CO2] at 5-10 cm, and for Firmicutes under elevated [CO2] (P < 0.05). Bacteria, archaea and fungi in soil responded differently to elevated [CO2], warming and their interaction. Taxa identified as significantly climate-responsive could show differing trends in the direction of response ('+' or '-') under elevated CO2 or warming, which could then not be used to

  3. Microbial enhanced heavy oil recovery by the aid of inhabitant spore-forming bacteria: an insight review.

    Science.gov (United States)

    Shibulal, Biji; Al-Bahry, Saif N; Al-Wahaibi, Yahya M; Elshafie, Abdulkader E; Al-Bemani, Ali S; Joshi, Sanket J

    2014-01-01

    Crude oil is the major source of energy worldwide being exploited as a source of economy, including Oman. As the price of crude oil increases and crude oil reserves collapse, exploitation of oil resources in mature reservoirs is essential for meeting future energy demands. As conventional recovery methods currently used have become less efficient for the needs, there is a continuous demand of developing a new technology which helps in the upgradation of heavy crude oil. Microbial enhanced oil recovery (MEOR) is an important tertiary oil recovery method which is cost-effective and eco-friendly technology to drive the residual oil trapped in the reservoirs. The potential of microorganisms to degrade heavy crude oil to reduce viscosity is considered to be very effective in MEOR. Earlier studies of MEOR (1950s) were based on three broad areas: injection, dispersion, and propagation of microorganisms in petroleum reservoirs; selective degradation of oil components to improve flow characteristics; and production of metabolites by microorganisms and their effects. Since thermophilic spore-forming bacteria can thrive in very extreme conditions in oil reservoirs, they are the most suitable organisms for the purpose. This paper contains the review of work done with thermophilic spore-forming bacteria by different researchers. PMID:24550702

  4. Microbial Enhanced Heavy Oil Recovery by the Aid of Inhabitant Spore-Forming Bacteria: An Insight Review

    Directory of Open Access Journals (Sweden)

    Biji Shibulal

    2014-01-01

    Full Text Available Crude oil is the major source of energy worldwide being exploited as a source of economy, including Oman. As the price of crude oil increases and crude oil reserves collapse, exploitation of oil resources in mature reservoirs is essential for meeting future energy demands. As conventional recovery methods currently used have become less efficient for the needs, there is a continuous demand of developing a new technology which helps in the upgradation of heavy crude oil. Microbial enhanced oil recovery (MEOR is an important tertiary oil recovery method which is cost-effective and eco-friendly technology to drive the residual oil trapped in the reservoirs. The potential of microorganisms to degrade heavy crude oil to reduce viscosity is considered to be very effective in MEOR. Earlier studies of MEOR (1950s were based on three broad areas: injection, dispersion, and propagation of microorganisms in petroleum reservoirs; selective degradation of oil components to improve flow characteristics; and production of metabolites by microorganisms and their effects. Since thermophilic spore-forming bacteria can thrive in very extreme conditions in oil reservoirs, they are the most suitable organisms for the purpose. This paper contains the review of work done with thermophilic spore-forming bacteria by different researchers.

  5. Selective enrichment of electrogenic bacteria for fuel cell application: Enumerating microbial dynamics using MiSeq platform.

    Science.gov (United States)

    Vamshi Krishna, K; Venkata Mohan, S

    2016-08-01

    This study is intended to examine the effect of pretreatment on selective enrichment of electrogenic bacteria from mixed culture. It has been observed that the iodopropane and heat-shock pretreatments suppress the growth of non-exoelectrons, while selecting only a limited number of strains belonging to genera Xanthomonas, Pseudomonas and Prevotella while untreated control inoculum showed more diverse community comprising of both exoelectrogens and non-exoelectrogens. High power output was observed in iodopropane (180mW/m(2)) pretreated microbial fuel cell (MFC) compared to heat-shock pretreated MFC (128mW/m(2)) and untreated control (92mW/m(2)). Coulombic efficiency of iodopropane and heat-shock pretreated MFC was higher compared to untreated control MFC, while drop in pH and volatile fatty acids (VFA) production was less in iodopropane pretreated MFC signifying the shifts in bacterial community structure toward electrogenesis instead of fermentation. These results signify the role of iodopropane and heat pretreatments on enrichment of electrogenic bacteria for fuel cell application. PMID:27061058

  6. Microbial leaching of iron from pyrite by moderate thermophile chemolithotropic bacteria

    International Nuclear Information System (INIS)

    The present work was aimed at studying the bioleachability of iron from pyrite by the selected moderately thermophilic strains of acidophilic chemolithotrophic and acidophilic heterotrophic bacteria. These included Sulfobacillus thermosulfidooxidans (chemolithotroph) and an un-identified strain of acidophilic heterotroph (code 6A1TSB) isolated from local environments. As compared to inoculated flasks, dissolution of metal (due to acid leaching) was significantly low in the un-inoculated control flasks in all the experiments in ore. A decrease in the bioleaching activity was observed at the later stages of bioleaching of metal from ore. Among the strategies adopted to enhance the metal leaching rates, a mixed consortium of the metal adapted cultures of the above-mentioned bacteria was found to exhibit the maximum metal leaching efficiency. In all the flasks where high metal leaching rates were observed, concomitantly biomass production rates were also high indicating high growth rates. It showed that the metal bioleaching capability of the bacteria was associated with their growth. Pyrite contained 42% iron. (author)

  7. Mercury-resistant bacteria from salt marsh of Tagus Estuary: the influence of plants presence and mercury contamination levels.

    Science.gov (United States)

    Figueiredo, Neusa L L; Areias, Andreia; Mendes, Ricardo; Canário, João; Duarte, Aida; Carvalho, Cristina

    2014-01-01

    Mercury (Hg) contamination of aquatic systems has been recognized as a global, serious problem affecting both wildlife and humans. High levels of Hg, in particular methylmercury (MeHg), were detected in surface sediments of Tagus Estuary. MeHg is neurotoxic and its concentration in aquatic systems is dependent upon the relative efficiency of reduction, methylation, and demethylation processes, which are mediated predominantly by the microbial community, in particular mercury-resistant (HgR) bacteria. Plants in contaminated ecosystems are known to take up Hg via plant roots. Therefore, the aims of this study were to (1) isolate and characterize HgR bacteria from a salt marsh of Tagus Estuary (Rosário) and (2) determine HgR bacteria levels in the rhizosphere and, consequently, their influence in metal cycling. To accomplish this objective, sediments samples were collected during the spring season in an area colonized by Sacocornia fruticosa and Spartina maritima and compared with sediments without plants. From these samples, 13 aerobic HgR bacteria were isolated and characterized morphologically, biochemically, and genetically, and susceptibility to Hg compounds, Hg(2+), and MeHg was assessed by determination of minimal inhibitory concentration (MIC). Genetically, the mer operon was searched by polymerase chain reaction (PCR) and 16S rRNA sequencing was used for bacterial identification. Results showed that the isolates were capable of growing in the presence of high Hg concentration with MIC values for HgCl2 and MeHgCl in the ranges of 1.7-4.2 μg/ml and 0.1-0.9 μg/ml, respectively. The isolates from sediments colonized with Sacocornia fruticosa displayed higher resistance levels compared to ones colonized with Spartina maritima. Bacteria isolates showed different capacity of Hg accumulation but all displayed Hg volatilization capabilities (20-50%). Mer operon was found in two isolates, which genetically confirmed their capability to convert Hg compounds by

  8. Effect of Probiotic Bacteria on Microbial Host Defense, Growth, and Immune Function in Human Immunodeficiency Virus Type-1 Infection

    Directory of Open Access Journals (Sweden)

    Stig Bengmark

    2011-12-01

    Full Text Available The hypothesis that probiotic administration protects the gut surface and could delay progression of Human Immunodeficiency Virus type1 (HIV-1 infection to the Acquired Immunodeficiency Syndrome (AIDS was proposed in 1995. Over the last five years, new studies have clarified the significance of HIV-1 infection of the gut associated lymphoid tissue (GALT for subsequent alterations in the microflora and breakdown of the gut mucosal barrier leading to pathogenesis and development of AIDS. Current studies show that loss of gut CD4+ Th17 cells, which differentiate in response to normal microflora, occurs early in HIV-1 disease. Microbial translocation and suppression of the T regulatory (Treg cell response is associated with chronic immune activation and inflammation. Combinations of probiotic bacteria which upregulate Treg activation have shown promise in suppressing pro inflammatory immune response in models of autoimmunity including inflammatory bowel disease and provide a rationale for use of probiotics in HIV-1/AIDS. Disturbance of the microbiota early in HIV-1 infection leads to greater dominance of potential pathogens, reducing levels of bifidobacteria and lactobacillus species and increasing mucosal inflammation. The interaction of chronic or recurrent infections, and immune activation contributes to nutritional deficiencies that have lasting consequences especially in the HIV-1 infected child. While effective anti-retroviral therapy (ART has enhanced survival, wasting is still an independent predictor of survival and a major presenting symptom. Congenital exposure to HIV-1 is a risk factor for growth delay in both infected and non-infected infants. Nutritional intervention after 6 months of age appears to be largely ineffective. A meta analysis of randomized, controlled clinical trials of infant formulae supplemented with Bifidobacterium lactis showed that weight gain was significantly greater in infants who received B. lactis compared to

  9. Microbial Diversity of Chromium-Contaminated Soils and Characterization of Six Chromium-Removing Bacteria

    Science.gov (United States)

    He, Zhiguo; Hu, Yuting; Yin, Zhen; Hu, Yuehua; Zhong, Hui

    2016-06-01

    Three soil samples obtained from different sites adjacent to a chromium slag heap in a steel alloy factory were taken to examine the effect of chromium contamination on soil bacterial diversity as determined by construction of 16S rDNA clone libraries and sequencing of selected clones based on restriction fragment length polymorphism (RFLP) analysis. Results revealed that Betaproteobacteria, Gammaproteobacteria, Firmicutes, and Alphaproteobacteria occurred in all three soil samples, although the three samples differed in their total diversity. Sample 1 had the highest microbial diversity covering 12 different classes, while Sample 3 had the lowest microbial diversity. Strains of six different species were successfully isolated, one of which was identified as Zobellella denitrificans. To our knowledge, this is the first report of a strain belonging to the genus Zobellella able to resist and reduce chromium. Among all isolates studied, Bacillus odysseyi YH2 exhibited the highest Cr(VI)-reducing capability, with a total removal of 23.5 % of an initial Cr(VI) concentration of 350 mg L-1.

  10. Differences in fungal and bacterial physiology alter soil carbon and nitrogen cycling: synthesizing effects of microbial community structure using the Fungi and Bacteria (FAB) model. (Invited)

    Science.gov (United States)

    Averill, C.; Hawkes, C. V.; Waring, B. G.

    2013-12-01

    Most biogeochemical models of soil carbon and nitrogen cycling include a simplified representation of the soil microbial community as a single pool, despite good evidence that shifts in the composition or relative abundance of microbial taxa can affect process rates. Incorporating a more realistic depiction of the microbial community in these models may increase their predictive accuracy, but this must be balanced against the feasibility of modeling the enormous diversity present in soil. We propose that explicitly including two major microbial functional groups with distinct physiologies, fungi and bacteria, will improve model predictions. To this end, we created the fungi and bacteria (FAB) model, building off previous enzyme-driven biogeochemical models that explicitly represent microbial physiology. We compared this model to a complementary biogeochemical model that does not include microbial community structure (';single-pool'). We also performed a cross-ecosystem meta-analysis of fungi-to-bacteria ratios to determine if model predictions of community structure matched empirical data. There were large differences in process rates and pool sizes between the single-pool and FAB models. In the FAB model, inorganic N pools were reduced by 5-95% depending on the soil C:N ratio due to bacterial immobilization of fungal mineralization products. This nitrogen subsidy also increased microbial biomass at some C:N ratios. Although there were changes in some components of respiration, particularly overflow respiration, there was no net effect of community structure on total respiration fluxes. The FAB model predicted a breakpoint in the relationship between the ratio of fungi to bacteria and soil C:N, after which the fungi-to-bacteria ratio should begin to increase. Break-point analysis of the meta-analysis data set revealed a consistent pattern and matched the slope of the change in F:B with soil C:N, but not the precise breakpoint. We argue that including microbial

  11. Xenorhodopsins, an enigmatic new class of microbial rhodopsins horizontally transferred between archaea and bacteria

    Directory of Open Access Journals (Sweden)

    Ugalde Juan A

    2011-10-01

    Full Text Available Abstract Based on unique, coherent properties of phylogenetic analysis, key amino acid substitutions and structural modeling, we have identified a new class of unusual microbial rhodopsins related to the Anabaena sensory rhodopsin (ASR protein, including multiple homologs not previously recognized. We propose the name xenorhodopsin for this class, reflecting a taxonomically diverse membership spanning five different Bacterial phyla as well as the Euryarchaeotal class Nanohaloarchaea. The patchy phylogenetic distribution of xenorhodopsin homologs is consistent with historical dissemination through horizontal gene transfer. Shared characteristics of xenorhodopsin-containing microbes include the absence of flagellar motility and isolation from high light habitats. Reviewers: This article was reviewed by Dr. Michael Galperin and Dr. Rob Knight.

  12. Modeling the influence of exopolymeric substances (EPS) extracted from Pseudomonas bacteria on chromium (III) sorption and transport in heterogeneous subsurface soils

    Science.gov (United States)

    Kantar, C.; Demiray, H.; Koleli, N.; Mercan, N.

    2009-04-01

    In situ remediation of soils contaminated with Cr(VI) is usually accomplished through microbial reduction of Cr(VI) to Cr(III) by soil microorganisms including Pseudomonas bacteria. Cr(VI) is a toxic substance that may stimulate the production of exopolymeric substances (EPS) by soil bacteria. Natural organic ligands such as EPS may have a pronounced impact on Cr(III) solubility, sorption, transport and bioavailability in subsurface systems. In this study, laboratory sorption and column experiments were performed to investigate the influence of exopolymeric substances (EPS) extracted from Pseudomonas aeruginosa P16, Pseudomonas putida P18 and Pseudomonas stutzeri P40 on chromium (III) sorption and transport in heterogeneous subsurface soils. The results from laboratory experiments indicate that microbial EPS enhanced Cr(III) solubility, which, in turn, led to an increase in Cr(III) transport through columns packed with subsurface soils under slightly acidic to alkaline pH conditions. A reactive transport code that includes a semi-empirical surface complexation model (SCM) to describe chemical processes e.g., sorption was used to simulate bench-scale column data for Cr(III) transport in the presence of EPS. Our transport simulations suggest that for an accurate simulation of Cr(III) transport in the presence of microbial EPS, the following processes and/or interactions need to be explicitly considered: 1) Cr(III)-EPS interactions; 2) binary soil/Cr and soil/EPS surface complexes; and 3) ternary soil/Cr/EPS complexes.

  13. Multi-targeted metagenetic analysis of the influence of climate and environmental parameters on soil microbial communities along an elevational gradient

    Science.gov (United States)

    Lanzén, Anders; Epelde, Lur; Blanco, Fernando; Martín, Iker; Artetxe, Unai; Garbisu, Carlos

    2016-01-01

    Mountain elevation gradients are invaluable sites for understanding the effects of climate change on ecosystem function, community structure and distribution. However, relatively little is known about the impact on soil microbial communities, in spite of their importance for the functioning of the soil ecosystem. Previous studies of microbial diversity along elevational gradients were often limited by confounding variables such as vegetation, pH, and nutrients. Here, we utilised a transect in the Pyrenees established to minimise variation in such parameters, to examine prokaryotic, fungal, protist and metazoan communities throughout three consecutive years. We aimed to determine the influences of climate and environmental parameters on soil microbial community structure; as well as on the relationships between those microbial communities. Further, functional diversity of heterotrophic bacteria was determined using Biolog. Prokaryotic and fungal community structure, but not alpha-diversity, correlated significantly with elevation. However, carbon-to-nitrogen ratio and pH appeared to affect prokaryotic and protist communities more strongly. Both community structure and physicochemical parameters varied considerably between years, illustrating the value of long-term monitoring of the dynamic processes controlling the soil ecosystem. Our study also illustrates both the challenges and strengths of using microbial communities as indicators of potential impacts of climate change. PMID:27321429

  14. Multi-targeted metagenetic analysis of the influence of climate and environmental parameters on soil microbial communities along an elevational gradient

    Science.gov (United States)

    Lanzén, Anders; Epelde, Lur; Blanco, Fernando; Martín, Iker; Artetxe, Unai; Garbisu, Carlos

    2016-06-01

    Mountain elevation gradients are invaluable sites for understanding the effects of climate change on ecosystem function, community structure and distribution. However, relatively little is known about the impact on soil microbial communities, in spite of their importance for the functioning of the soil ecosystem. Previous studies of microbial diversity along elevational gradients were often limited by confounding variables such as vegetation, pH, and nutrients. Here, we utilised a transect in the Pyrenees established to minimise variation in such parameters, to examine prokaryotic, fungal, protist and metazoan communities throughout three consecutive years. We aimed to determine the influences of climate and environmental parameters on soil microbial community structure; as well as on the relationships between those microbial communities. Further, functional diversity of heterotrophic bacteria was determined using Biolog. Prokaryotic and fungal community structure, but not alpha-diversity, correlated significantly with elevation. However, carbon-to-nitrogen ratio and pH appeared to affect prokaryotic and protist communities more strongly. Both community structure and physicochemical parameters varied considerably between years, illustrating the value of long-term monitoring of the dynamic processes controlling the soil ecosystem. Our study also illustrates both the challenges and strengths of using microbial communities as indicators of potential impacts of climate change.

  15. In Situ Microbial Community Succession on Mild Steel in Estuarine and Marine Environments: Exploring the Role of Iron-Oxidizing Bacteria.

    Science.gov (United States)

    McBeth, Joyce M; Emerson, David

    2016-01-01

    Microbiologically influenced corrosion (MIC) is a complex biogeochemical process involving interactions between microbes, metals, minerals, and their environment. We hypothesized that sediment-derived iron-oxidizing bacteria (FeOB) would colonize and become numerically abundant on steel surfaces incubated in coastal marine environments. To test this, steel coupons were incubated on sediments over 40 days, and samples were taken at regular intervals to examine microbial community succession. The experiments were conducted at two locations: (1) a brackish salt marsh stream and (2) a coastal marine bay. We analyzed DNA extracted from the MIC biofilms for bacterial diversity using high-throughput amplicon sequencing of the SSU rRNA gene, and two coupons from the coastal site were single cell sorted and screened for the SSU rRNA gene. We quantified communities of Zetaproteobacteria, sulfate-reducing bacteria (SRB), and total bacteria and archaea using qPCR analyses. Zetaproteobacteria and SRB were identified in the sequencing data and qPCR analyses for samples collected throughout the incubations and were also present in adjacent sediments. At the brackish site, the diversity of Zetaproteobacteria was lower on the steel compared to sediments, consistent with the expected enrichment of FeOB on steel. Their numbers increased rapidly over the first 10 days. At the marine site, Zetaproteobacteria and other known FeOB were not detected in sediments; however, the numbers of Zetaproteobacteria increased dramatically within 10 days on the steel surface, although their diversity was nearly clonal. Iron oxyhydroxide stalk biosignatures were observed on the steel and in earlier enrichment culture studies; this is evidence that the Zetaproteobacteria identified in the qPCR, pyrosequencing, and single cell data were likely FeOB. In the brackish environment, members of freshwater FeOB were also present, but were absent in the fully marine site. This work indicates there is a

  16. In situ microbial community succession on mild steel in estuarine and marine environments: exploring the role of iron-oxidizing bacteria

    Directory of Open Access Journals (Sweden)

    Joyce Margaret Mcbeth

    2016-05-01

    Full Text Available Microbiologically influenced corrosion (MIC is a complex biogeochemical process involving interactions between microbes, metals, minerals, and their environment. We hypothesized that sediment-derived iron-oxidizing bacteria (FeOB would colonize and become numerically abundant on steel surfaces incubated in coastal marine environments. To test this, steel coupons were incubated on sediments over 40 days, and samples were taken at regular intervals to examine microbial community succession. The experiments were conducted at two locations: (1 a brackish salt marsh stream and (2 a coastal marine bay. We analyzed DNA extracted from the MIC biofilms for bacterial diversity using high-throughput amplicon sequencing of the SSU rRNA gene, and two coupons from the coastal site were single cell sorted and screened for the SSU rRNA gene. We quantified communities of Zetaproteobacteria, sulfate-reducing bacteria (SRB, and total bacteria and archaea using qPCR analyses. Zetaproteobacteria and SRB were identified in the sequencing data and qPCR analyses for samples collected throughout the incubations and were also present in adjacent sediments. At the brackish site, the diversity of Zetaproteobacteria were lower on the steel compared to sediments, consistent with the expected enrichment of FeOB on steel. Their numbers increased rapidly over the first 10 days. At the marine site, Zetaproteobacteria and other known FeOB were not detected in sediments; however the numbers of Zetaproteobacteria increased dramatically within ten days on the steel surface, although their diversity was nearly clonal. Iron oxyhydroxide stalk biosignatures were observed on the steel and in earlier enrichment culture studies; this is evidence that the Zetaproteobacteria identified in the qPCR, pyrosequencing, and single cell data were likely FeOB. In the brackish environment, members of freshwater FeOB were also present, but were absent in the fully marine site. This work indicates

  17. Bacteria associated with human saliva are major microbial components of Ecuadorian indigenous beers (chicha).

    Science.gov (United States)

    Freire, Ana L; Zapata, Sonia; Mosquera, Juan; Mejia, Maria Lorena; Trueba, Gabriel

    2016-01-01

    Indigenous beers (chicha) are part of the indigenous culture in Ecuador. The fermentation process of these beers probably relies on microorganisms from fermented substrates, environment and human microbiota. We analyzed the microbiota of artisanal beers (including a type of beer produced after chewing boiled cassava) using bacterial culture and 16S ribosomal RNA (rRNA) gene-based tag-encoded FLX amplicon pyrosequencing (bTEFAP). Surprisingly, we found that Streptococcus salivarius and Streptococcus mutans (part of the human oral microbiota) were among the most abundant bacteria in chewed cassava and in non-chewed cassava beers. We also demonstrated that S. salivarius and S. mutans (isolated from these beers) could proliferate in cassava mush. Lactobacillus sp. was predominantly present in most types of Ecuadorian chicha.

  18. Microbial control of the production of hydrogen sulfide by sulfate-reducing bacteria.

    Science.gov (United States)

    Montgomery, A D; McLnerney, M J; Sublette, K L

    1990-03-01

    A sulfide-resistant ctrain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium or in Berea sandstone cores. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. These data suggest that strain F would be effective in controlling sulfide production in oil reservoirs and other environments.

  19. A generic transport-reactive model for simulating microbially influenced mineral precipitation in porous medium

    NARCIS (Netherlands)

    Zhou, J.; Van Turnhout, A.G.; Heimovaara, T.J.; Afanasyev, M.

    2015-01-01

    The spatial and temporal distribution of precipitated minerals is one of the key factors governing various processes in the sub-surface environment, including microbially influenced corrosion (MIC) (Huang, 2002), bio-cementation (van Paassen et al., 2010) and sediment diagenesis (Paraska et al., 201

  20. Bioaugmentation of anaerobic sludge digestion with iron-reducing bacteria: process and microbial responses to variations in hydraulic retention time.

    Science.gov (United States)

    Baek, Gahyun; Kim, Jaai; Shin, Seung Gu; Lee, Changsoo

    2016-01-01

    Although anaerobic digestion (AD) is a widely used option to manage waste activated sludge (WAS), there are some drawbacks related to its slow reaction rate and low energy productivity. This study examined an anaerobic WAS digester, augmented with an iron-reducing microbial consortium, relative to changes in microbial community structure and process performance at decreasing hydraulic retention times (HRTs) of 20 to 10 days. The enhanced methanation performance (approximately 40 % increase in methane yield) by the bioaugmentation was sustained until the HRT was decreased to 12.5 days, under Fe(3+)-rich conditions (ferric oxyhydroxide, 20 mM Fe). Enhanced iron-reducing activity was evidenced by the increased Fe(2+) to total Fe ratio maintained above 50 % during the stable operational phases. A further decrease in HRT to 10 days resulted in a significant performance deterioration, along with a drop in the Fe(2+) to total Fe ratio to <35 %, after four turnovers of operation. Prevailing existence of putative iron-reducing bacteria (IRBs) was identified by denaturing gradient gel electrophoresis (DGGE), with Spirochaetaceae- and Thauera-related organisms being dominant members, and clear dominance shifts among them with respect to decrease in HRT were observed. Lowering HRT led to evident shifts in bacterial community structure likely associated with washout of IRBs, leading to decreases in iron respiration activity and AD performance at a lower HRT. The bacterial community structure shifted dynamically over phases, and the community transitions correlated well with the changes in process performance. Overall, the combined biostimulation and bioaugmentation investigated in this study proved effective for enhanced methane recovery from anaerobic WAS digestion, which suggests an interesting potential for high-rate AD.

  1. Bioaugmentation of anaerobic sludge digestion with iron-reducing bacteria: process and microbial responses to variations in hydraulic retention time.

    Science.gov (United States)

    Baek, Gahyun; Kim, Jaai; Shin, Seung Gu; Lee, Changsoo

    2016-01-01

    Although anaerobic digestion (AD) is a widely used option to manage waste activated sludge (WAS), there are some drawbacks related to its slow reaction rate and low energy productivity. This study examined an anaerobic WAS digester, augmented with an iron-reducing microbial consortium, relative to changes in microbial community structure and process performance at decreasing hydraulic retention times (HRTs) of 20 to 10 days. The enhanced methanation performance (approximately 40 % increase in methane yield) by the bioaugmentation was sustained until the HRT was decreased to 12.5 days, under Fe(3+)-rich conditions (ferric oxyhydroxide, 20 mM Fe). Enhanced iron-reducing activity was evidenced by the increased Fe(2+) to total Fe ratio maintained above 50 % during the stable operational phases. A further decrease in HRT to 10 days resulted in a significant performance deterioration, along with a drop in the Fe(2+) to total Fe ratio to <35 %, after four turnovers of operation. Prevailing existence of putative iron-reducing bacteria (IRBs) was identified by denaturing gradient gel electrophoresis (DGGE), with Spirochaetaceae- and Thauera-related organisms being dominant members, and clear dominance shifts among them with respect to decrease in HRT were observed. Lowering HRT led to evident shifts in bacterial community structure likely associated with washout of IRBs, leading to decreases in iron respiration activity and AD performance at a lower HRT. The bacterial community structure shifted dynamically over phases, and the community transitions correlated well with the changes in process performance. Overall, the combined biostimulation and bioaugmentation investigated in this study proved effective for enhanced methane recovery from anaerobic WAS digestion, which suggests an interesting potential for high-rate AD. PMID:26428233

  2. Influence of microstructure on the microbial corrosión behaviour of stainless steels

    OpenAIRE

    Moreno, Diego Alejandro; Ibars, José Ramón; Ranninger, Carlos

    2000-01-01

    Several stainless steels (Types UNS S30300, S30400, S30403, S31600, S31603 and S42000) with different microstructural characteristics have been used to study the influence of heat treatments on microbiologically influenced corrosion (MIC). Biocorrosion and accelerated electrochemical testing was performed in various microbiological media. Two species of sulphate-reducing bacteria (SRB) have been used in order to ascertain the influence of microstructure. The morphology of corrosion pits produ...

  3. Influence of Fishmeal-Free Diets on Microbial Communities in Atlantic Salmon (Salmo salar) Recirculation Aquaculture Systems

    Science.gov (United States)

    Schmidt, Victor; Davidson, John; Summerfelt, Steven

    2016-01-01

    ABSTRACT Reliance on fishmeal as a primary protein source is among the chief economic and environmental concerns in aquaculture today. Fishmeal-based feeds often require harvest from wild fish stocks, placing pressure on natural ecosystems and causing price instability. Alternative diet formulations without the use of fishmeal provide a potential solution to this challenge. Although the impact of alternative diets on fish performance, intestinal inflammation, palatability, and gut microbiota has been a topic of recent interest, less is known about how alternative feeds impact the aquaculture environment as a whole. The recent focus on recirculating aquaculture systems (RAS) and the closed-containment approach to raising food fish highlights the need to maintain stable environmental and microbiological conditions within a farm environment. Microbial stability in RAS biofilters is particularly important, given its role in nutrient processing and water quality in these closed systems. If and how the impacts of alternative feeds on microbial communities in fish translate into changes to the biofilters are not known. We tested the influence of a fishmeal-free diet on the microbial communities in RAS water, biofilters, and salmon microbiomes using high-throughput 16S rRNA gene V6 hypervariable region amplicon sequencing. We grew Atlantic salmon (Salmo salar) to market size in six replicate RAS tanks, three with traditional fishmeal diets and three with alternative-protein, fishmeal-free diets. We sampled intestines and gills from market-ready adult fish, water, and biofilter medium in each corresponding RAS unit. Our results provide data on how fish diet influences the RAS environment and corroborate previous findings that diet has a clear influence on the microbiome structure of the salmon intestine, particularly within the order Lactobacillales (lactic acid bacteria). We conclude that the strong stability of taxa likely involved in water quality processing regardless

  4. Coliform bacteria in New Jersey domestic wells: influence of geology, laboratory, and method.

    Science.gov (United States)

    Atherholt, Thomas B; Bousenberry, Raymond T; Carter, Gail P; Korn, Leo R; Louis, Judith B; Serfes, Michael E; Waller, Debra A

    2013-01-01

    Following passage of the New Jersey Private Well Testing Act, 50,800 domestic wells were tested between 2002 and 2007 for the presence of total coliform (TC) bacteria. Wells containing TC bacteria were further tested for either fecal coliform or Escherichia coli (FC/E. coli) bacteria. Analysis of the data, generated by 39 laboratories, revealed that the rate of coliform detections in groundwater (GW) was influenced by the laboratory and the method used, and also by geology. Based on one sample per well, TC and FC/E. coli were detected in wells located in bedrock 3 and 3.7 times more frequently, respectively, than in wells located in the unconsolidated strata of the Coastal Plain. In bedrock, detection rates were higher in sedimentary rock than in igneous or metamorphic rock. Ice-age glaciers also influenced detection rates, most likely by removing material in some areas and depositing thick layers of unconsolidated material in other areas. In bedrock, coliform bacteria were detected more often in wells with a pH of 3 to 6 than in wells with a pH of 7 to 10 whereas the reverse was true in the Coastal Plain. TC and FC/E. coli bacteria were detected in 33 and 9.5%, respectively, of sedimentary rock wells with pH 3 to 6. Conversely, for Coastal Plain wells with pH 3 to 6, detection rates were 4.4% for TC and 0.6% for FC/E. coli.

  5. Corrosion of low alloy steels in natural seawater. Influence of alloying elements and bacteria

    International Nuclear Information System (INIS)

    Metallic infrastructures immersed in natural seawater are exposed to important corrosion phenomena, sometimes characterised as microbiologically influenced corrosion. The presence of alloying elements in low alloy steels could present a corrosion resistance improvement of the structures. In this context, tests are performed with commercial steel grades, from 0,05 wt pc Cr to 11,5 wt pc Cr. They consist in 'on site' immersion in natural seawater on the one hand, and in laboratory tests with immersion in media enriched with marine sulphide-producing bacteria on the other hand. Gravimetric, microbiological, electrochemical measurements and corrosion product analyses are carried out and show that corrosion phenomenon is composed of several stages. A preliminary step is the reduction of the corrosion kinetics and is correlated with the presence of sessile sulphide-producing bacteria and an important formation of sulphur-containing species. This phase is shorter when the alloying element content of the steel increases. This phase is probably followed by an increase of corrosion, appearing clearly after an 8-month immersion in natural seawater for some of the grade steels. Chromium and molybdenum show at the same time a beneficial influence to generalised corrosion resistance and a toxic effect on sulphide-producing bacteria. This multidisciplinary study reflects the complexity of the interactions between bacteria and steels; sulphide-producing bacteria seem to be involved in corrosion processes in natural seawater and complementary studies would have to clarify occurring mechanisms. (author)

  6. Microbial diversity of soil bacteria in agricultural field contaminated with heavy metals

    Institute of Scientific and Technical Information of China (English)

    CHIEN Chihching; KUO Yumei; CHEN Changchieh; HUNG Chunwei; YEH Chihwei; YEH Weijen

    2008-01-01

    In this study we evaluated the bacterial diversity in a soil sample from a site next to a chemical industrial factory previously contaminated with heavy metals.Analysis of 16S rDNA sequences amplified from DNA directly extracted from the soil revealed 17 different bacterial types (genera and/or species).They included Polyangium spp.,Sphingomonas spp.,Variovorax spp.,Hafina spp.,Clostridia,Acidobacteria,the enterics and some uncultured strains.Microbes able to tolerate high concentrations of cadmium (500 μmol/L and above) were also isolated from the soil.These isolates included strains of Acinetobacter (strain CD06),Enterobacter sp.(strains CD01,CD03,CD04 and CD08) (similar strains also identified inculture-independent approach) and a strain of Stenotrophomonas sp.The results indicated that the species identified from direct analysis of 16S rDNA of the soil can be quite different from those strains obtained from enrichment eultttres and the microbial activities for heavy metal resistance might be more appropriately addressed by the actual isolates.

  7. A vast collection of microbial genes that are toxic to bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Kimelman, Aya; Levy, Asaf; Sberro, Hila; Kidron, Shahar; Leavitt, Azita; Amitai, Gil; Yoder-Himes, Deborah; Wurtzel, Omri; Zhu, Yiwen; Rubin, Edward M; Sorek, Rotem

    2012-02-02

    In the process of clone-based genome sequencing, initial assemblies frequently contain cloning gaps that can be resolved using cloning-independent methods, but the reason for their occurrence is largely unknown. By analyzing 9,328,693 sequencing clones from 393 microbial genomes we systematically mapped more than 15,000 genes residing in cloning gaps and experimentally showed that their expression products are toxic to the Escherichia coli host. A subset of these toxic sequences was further evaluated through a series of functional assays exploring the mechanisms of their toxicity. Among these genes our assays revealed novel toxins and restriction enzymes, and new classes of small non-coding toxic RNAs that reproducibly inhibit E. coli growth. Further analyses also revealed abundant, short toxic DNA fragments that were predicted to suppress E. coli growth by interacting with the replication initiator dnaA. Our results show that cloning gaps, once considered the result of technical problems, actually serve as a rich source for the discovery of biotechnologically valuable functions, and suggest new modes of antimicrobial interventions.

  8. Identification of bacteria used for microbial enhanced oil recovery process by fluorescence in situ hybridization technique

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, K.; Tanaka, S.; Otsuka, M. [Kansai Research Institute, Kyoto (Japan). Lifescience Lab.; Yonebayashi, H. [Japan National Oil Corp., Chiba (Japan). Tech. Research Center; Enomoto, H. [Tohoku University, Sendai (Japan). Dept. of Geoscience and Tech.

    2000-01-01

    A fluorescence in situ hybridization (FISH) technique using 16S rRNA-targeted oligonucleotide probes was developed for rapid detection of microorganisms for use in the microbial enhancement of oil recovery (MEOR) process. Two microorganisms, Enterobacter cloacae TRC-322 and Bacillus licheniformis TRC-18-2-a, were selected from a collection of Enterobacter sp. and Bacillus sp. which were screened in previous studies as candidate microorganisms for injection, and were used for this experiment. Oligonucleotide probes, design based on specific sequences in the 16S rRNA gene were labeled with either fluorescein isothiocyanate (FITC), or 6-car-boxy-X-rhodamine (ROX), and were allowed to hybridize with fixed cells of the two microorganisms noted above. The fluorescence signal emitted from each microorganism cells could clearly be detected by an epifluorescence microscope. Moreover, E. cloacae TRC-322 and B, licheniformis TRC-18-2-a, suspended in actual reservoir brine, including inorganic salts, oil and aboriginal cells of the reservoir brine, could be detected directly by this hybridization method, without the need for cultivation and isolation. (author)

  9. A vast collection of microbial genes that are toxic to bacteria.

    Science.gov (United States)

    Kimelman, Aya; Levy, Asaf; Sberro, Hila; Kidron, Shahar; Leavitt, Azita; Amitai, Gil; Yoder-Himes, Deborah R; Wurtzel, Omri; Zhu, Yiwen; Rubin, Edward M; Sorek, Rotem

    2012-04-01

    In the process of clone-based genome sequencing, initial assemblies frequently contain cloning gaps that can be resolved using cloning-independent methods, but the reason for their occurrence is largely unknown. By analyzing 9,328,693 sequencing clones from 393 microbial genomes, we systematically mapped more than 15,000 genes residing in cloning gaps and experimentally showed that their expression products are toxic to the Escherichia coli host. A subset of these toxic sequences was further evaluated through a series of functional assays exploring the mechanisms of their toxicity. Among these genes, our assays revealed novel toxins and restriction enzymes, and new classes of small, non-coding toxic RNAs that reproducibly inhibit E. coli growth. Further analyses also revealed abundant, short, toxic DNA fragments that were predicted to suppress E. coli growth by interacting with the replication initiator DnaA. Our results show that cloning gaps, once considered the result of technical problems, actually serve as a rich source for the discovery of biotechnologically valuable functions, and suggest new modes of antimicrobial interventions.

  10. Environmental Factors Influencing the Structural Dynamics of Soil Microbial Communities During Assisted Phytostabilization of Acid-Generating Mine Tailings: a Mesocosm Experiment

    Science.gov (United States)

    Valentín-Vargas, Alexis; Root, Robert A.; Neilson, Julia W; Chorover, Jon; Maier, Raina M.

    2014-01-01

    Compost-assisted phytostabilization has recently emerged as a robust alternative for reclamation of metalliferous mine tailings. Previous studies suggest that root-associated microbes may be important for facilitating plant establishment on the tailings, yet little is known about the long-term dynamics of microbial communities during reclamation. A mechanistic understanding of microbial community dynamics in tailings ecosystems undergoing remediation is critical because these dynamics profoundly influence both the biogeochemical weathering of tailings and the sustainability of a plant cover. Here we monitor the dynamics of soil microbial communities (i.e. bacteria, fungi, archaea) during a 12-month mesocosm study that included 4 treatments: 2 unplanted controls (unamended and compost-amended tailings) and 2 compost-amended seeded tailings treatments. Bacterial, fungal and archaeal communities responded distinctively to the revegetation process and concurrent changes in environmental conditions and pore water chemistry. Compost addition significantly increased microbial diversity and had an immediate and relatively long-lasting buffering-effect on pH, allowing plants to germinate and thrive during the early stages of the experiment. However, the compost buffering capacity diminished after six months and acidification took over as the major factor affecting plant survival and microbial community structure. Immediate changes in bacterial communities were observed following plant establishment, whereas fungal communities showed a delayed response that apparently correlated with the pH decline. Fluctuations in cobalt pore water concentrations, in particular, had a significant effect on the structure of all three microbial groups, which may be linked to the role of cobalt in metal detoxification pathways. The present study represents, to our knowledge, the first documentation of the dynamics of the three major microbial groups during revegetation of compost

  11. Microbially Influenced Corrosion of 304 Stainless Steel and Titanium by P. variotii and A. niger in Humid Atmosphere

    Science.gov (United States)

    Zhang, Dawei; Zhou, Feichi; Xiao, Kui; Cui, Tianyu; Qian, Hongchong; Li, Xiaogang

    2015-07-01

    Microbially induced corrosion (MIC) poses significant threats to reliability and safety of engineering materials and structures. While most MIC studies focus on prokaryotic bacteria such as sulfate-reducing bacteria, the influence of fungi on corrosion behaviors of metals has not been adequately reported. In this study, 304 stainless steel and titanium were exposed to two very common fungi, Paecilomyces variotii, Aspergillus niger and their mixtures under highly humid atmosphere. The initial corrosion behaviors within 28 days were studied via scanning Kelvin probe, which showed marked surface ennoblement and increasingly heterogeneous potential distribution upon prolonged fungus exposure. Using stereomicroscopy, fungus growth as well as corrosion morphology of 304 stainless steel and titanium were also evaluated after a long-term exposure for 60 days. The presence of fungi decreased the corrosion resistance for both 304 stainless steel and titanium. Titanium showed higher resistance to fungus growth and the induced corrosion. Exposure to the mixed strains resulted in the highest fungus growth rate but the mildest corrosion, possibly due to the decreased oxygen level by increased fungal activities.

  12. Arctic microbial community dynamics influenced by elevated CO2 levels

    Science.gov (United States)

    Brussaard, C. P. D.; Noordeloos, A. A. M.; Witte, H.; Collenteur, M. C. J.; Schulz, K.; Ludwig, A.; Riebesell, U.

    2013-02-01

    The Arctic Ocean ecosystem is particularly vulnerable to ocean acidification (OA) related alterations due to the relatively high CO2 solubility and low carbonate saturation states of its cold surface waters. Thus far, however, there is only little known about the consequences of OA on the base of the food web. In a mesocosm CO2-enrichment experiment (overall CO2 levels ranged from ~ 180 to 1100 μatm) in Kongsfjorden off Svalbard, we studied the consequences of OA on a natural pelagic microbial community. OA distinctly affected the composition and growth of the Arctic phytoplankton community, i.e. the picoeukaryotic photoautotrophs and to a lesser extent the nanophytoplankton thrived. A shift towards the smallest phytoplankton as a result of OA will have direct consequences for the structure and functioning of the pelagic food web and thus for the biogeochemical cycles. Besides being grazed, the dominant pico- and nanophytoplankton groups were found prone to viral lysis, thereby shunting the carbon accumulation in living organisms into the dissolved pools of organic carbon and subsequently affecting the efficiency of the biological pump in these Arctic waters.

  13. Arctic microbial community dynamics influenced by elevated CO2 levels

    Directory of Open Access Journals (Sweden)

    K. Schulz

    2012-09-01

    Full Text Available The Arctic Ocean ecosystem is particular vulnerable for ocean acidification (OA related alterations due to the relatively high CO2 solubility and low carbonate saturation states of its cold surface waters. Thus far, however, there is only little known about the consequences of OA on the base of the food web. In a mesocosm CO2-enrichment experiment (overall CO2 levels ranged from ∼180 to 1100 μatm in the Kongsfjord off Svalbard, we studied the consequences of OA on a natural pelagic microbial community. The most prominent finding of our study is the profound effect of OA on the composition and growth of the Arctic phytoplankton community, i.e. the picoeukaryotic photoautotrophs and to a lesser extent the nanophytoplankton prospered. A shift towards the smallest phytoplankton as a result of OA will have direct consequences for the structure and functioning of the pelagic food web and thus for the biogeochemical cycles. Furthermore, the dominant pico- and nanophytoplankton groups were found prone to viral lysis, thereby shunting the carbon accumulation in living organisms into the dissolved pools of organic carbon and subsequently affecting the efficiency of the biological pump in these Arctic waters.

  14. The performance of the microbial fuel cell-coupled constructed wetland system and the influence of the anode bacterial community.

    Science.gov (United States)

    Li, Tingting; Fang, Zhou; Yu, Ran; Cao, Xian; Song, Hailiang; Li, Xianning

    2016-01-01

    In order to analyse the influences of substrate and electrode on the performance of microbial fuel cell-coupled constructed wetland (CW-MFC), the electrical generation efficiencies, the decolourization mechanism of reactive brilliant red X-3B, and the microbial communities in the anode were investigated. The closed circuit reactor fed with a mixture of X-3B and glucose (166.7 mg/L X-3B and 140 mg/L glucose) (the mixture CC reactor) got a decolourization rate of 92.79%, which was higher than the open circuit reactor (the mixture OC reactor) and the reactor fed with X-3B (the X-3B reactor). The mixture CC reactor got a maximum power density of 0.200 W/m(3), which was much higher than the X-3B reactor. The intermediates produced by X-3B decolourization were further degraded in CW-MCs. The PCR-denatured gradient gel electrophoresis analysis indicated the dominance of Proteobacteria-like 16S rRNA gnen sequences. The brightest band was detected to be dominant by a Lactobacillus kefiranofaciens-like sequence. The electrogenic bacteria-associated sequences, such as Geobacter metallireducens and Desulfobulbaceae, both existed in the closed circuit and the open circuit reactors, accompanied with Desulfobacterium sp., Klebsiella sp., Aminobacter sp., Flavobacterium sp., Thauera aromatic, and Sphingomonas sp. The abundances of Geobacter sulfurreducens and Betaproteobacteria in the mixture CC reactor were 32.2% and 7.2%, respectively, and were higher than those in the mixture OC reactor. In summary, substrate and electrode can promote the performance of the CW-MFC and have effects on the microbial community in the anode of the CW-MFC. PMID:26652300

  15. Microbial diversity of a Brazilian coastal region influenced by an upwelling system and anthropogenic activity.

    Directory of Open Access Journals (Sweden)

    Juliano C Cury

    Full Text Available BACKGROUND: Upwelling systems are characterised by an intense primary biomass production in the surface (warmest water after the outcrop of the bottom (coldest water, which is rich in nutrients. Although it is known that the microbial assemblage plays an important role in the food chain of marine systems and that the upwelling systems that occur in southwest Brazil drive the complex dynamics of the food chain, little is known about the microbial composition present in this region. METHODOLOGY/PRINCIPAL FINDINGS: We carried out a molecular survey based on SSU rRNA gene from the three domains of the phylogenetic tree of life present in a tropical upwelling region (Arraial do Cabo, Rio de Janeiro, Brazil. The aim was to analyse the horizontal and vertical variations of the microbial composition in two geographically close areas influenced by anthropogenic activity (sewage disposal/port activity and upwelling phenomena, respectively. A lower estimated diversity of microorganisms of the three domains of the phylogenetic tree of life was found in the water of the area influenced by anthropogenic activity compared to the area influenced by upwelling phenomena. We observed a heterogenic distribution of the relative abundance of taxonomic groups, especially in the Archaea and Eukarya domains. The bacterial community was dominated by Proteobacteria, Cyanobacteria and Bacteroidetes phyla, whereas the microeukaryotic community was dominated by Metazoa, Fungi, Alveolata and Stramenopile. The estimated archaeal diversity was the lowest of the three domains and was dominated by uncharacterised marine Crenarchaeota that were most closely related to Marine Group I. CONCLUSIONS/SIGNIFICANCE: The variety of conditions and the presence of different microbial assemblages indicated that the area of Arraial do Cabo can be used as a model for detailed studies that contemplate the correlation between pollution-indicating parameters and the depletion of microbial

  16. Fluorescently labeled bacteria provide insight on post-mortem microbial transmigration.

    Science.gov (United States)

    Burcham, Z M; Hood, J A; Pechal, J L; Krausz, K L; Bose, J L; Schmidt, C J; Benbow, M E; Jordan, H R

    2016-07-01

    Microbially mediated mechanisms of human decomposition begin immediately after death, and are a driving force for the conversion of a once living organism to a resource of energy and nutrients. Little is known about post-mortem microbiology in cadavers, particularly the community structure of microflora residing within the cadaver and the dynamics of these communities during decomposition. Recent work suggests these bacterial communities undergo taxa turnover and shifts in community composition throughout the post-mortem interval. In this paper we describe how the microbiome of a living host changes and transmigrates within the body after death thus linking the microbiome of a living individual to post-mortem microbiome changes. These differences in the human post-mortem from the ante-mortem microbiome have demonstrated promise as evidence in death investigations. We investigated the post-mortem structure and function dynamics of Staphylococcus aureus and Clostridium perfringens after intranasal inoculation in the animal model Mus musculus L. (mouse) to identify how transmigration of bacterial species can potentially aid in post-mortem interval estimations. S. aureus was tracked using in vivo and in vitro imaging to determine colonization routes associated with different physiological events of host decomposition, while C. perfringens was tracked using culture-based techniques. Samples were collected at discrete time intervals associated with various physiological events and host decomposition beginning at 1h and ending at 60 days post-mortem. Results suggest that S. aureus reaches its highest concentration at 5-7 days post-mortem then begins to rapidly decrease and is undetectable by culture on day 30. The ability to track these organisms as they move in to once considered sterile space may be useful for sampling during autopsy to aid in determining post-mortem interval range estimations, cause of death, and origins associated with the geographic location of human

  17. [Opportunistic bacteria and microbial flora in children with leukemia and neutropenic enterocolitis].

    Science.gov (United States)

    García-Elorriaga, Guadalupe; Corona-de Los Santos, Juan C; Méndez-Tovar, Socorro; del Rey-Pineda, Guillermo; Pérez-Casillas, Ruy X

    2013-01-01

    Objetivo: determinar la microbiota y la prevalencia de microorganismos oportunistas en niños con leucemia y enterocolitis neutropénica. Métodos: se realizó un estudio prospectivo observacional en pacientes con leucemia aguda y neutropenia. Se tomaron cultivos de heces para identificar la presencia de bacterias y microbiota. Se aplicó estadística descriptiva para su análisis. Resultados: fueron incluidos 21 pacientes (12 hombres, 57.1 %). En 68 % de los coprocultivos se observó desarrollo de microorganismos gramnegativos. La presencia de microorganismos grampositivos fue de 20 %, 6 % de Candida sp., 3 % de Cryptosporidium sp. y en 3 % se observaron bacilos ácido alcohol resistentes. Staphylococcus epidermidis, Enterobacter sp., y Escherichia coli se observaron en cultivo puro. No se encontró asociación entre microorganismos grampositivos y gramnegativos con la edad, el recuento leucocitario ni el cultivo puro o mixto.Conclusiones: aunque los microorganismos gramnegativos fueron los más frecuentes, se aislaron de manera importante grampositivos y otros que no se buscan de rutina en el coprocultivo.

  18. Influence of microbial acitivity on the stability of activated sludge flocs

    DEFF Research Database (Denmark)

    Wilén, Britt-Marie; Nielsen, Jeppe Lund; Keiding, Kristian;

    2000-01-01

    . These results strongly suggested that microorganisms using oxygen and/or nitrate as electron acceptors were important for maintaining the floc strength. The increase in turbidity under deflocculation was well correlated with the number of bacteria and concentration of protein, humic substances and...... anaerobic biological activity. When anaerobic conditions prevailed, a microbial iron reduction immediately started with iron reduction rates of 4–150 μmol/gVS·h. Subsequently, a decrease in floc strength was observed which could also be observed when the iron-reducing bacterium Shewanella alga BrY was added...

  19. Metabolomic applications to decipher gut microbial metabolic influence in health and disease

    Directory of Open Access Journals (Sweden)

    Francois-Pierre eMartin

    2012-04-01

    Full Text Available Dietary preferences and nutrients composition have been shown to influence human and gut microbial metabolism, which ultimately has specific effects on health and diseases’ risk. Increasingly, results from molecular biology and microbiology demonstrate the key role of the gut microbiota metabolic interface to the overall mammalian host’s health status. There is therefore raising interest in nutrition research to characterize the molecular foundations of the gut microbial mammalian cross-talk at both physiological and biochemical pathway levels. Tackling these challenges can be achieved through systems biology approaches, such as metabolomics, to underpin the highly complex metabolic exchanges between diverse biological compartments, including organs, systemic biofluids and microbial symbionts. By the development of specific biomarkers for prediction of health and disease, metabolomics is increasingly used in clinical applications as regard to disease aetiology, diagnostic stratification and potentially mechanism of action of therapeutical and nutraceutical solutions. Surprisingly, an increasing number of metabolomics investigations in pre-clinical and clinical studies based on proton nuclear magnetic resonance (1H NMR spectroscopy and mass spectrometry (MS provided compelling evidence that system wide and organ-specific biochemical processes are under the influence of gut microbial metabolism. This review aims at describing recent applications of metabolomics in clinical fields where main objective is to discern the biochemical mechanisms under the influence of the gut microbiota, with insight into gastrointestinal health and diseases diagnostics and improvement of homeostasis metabolic regulation.

  20. Microbially influenced corrosion of Fe, Ni, Cu, Al, and Ti based weldments in a marine environment

    Energy Technology Data Exchange (ETDEWEB)

    Buchanan, R.A.; Kovacs, A.L.; Lundin, C.D.; Khan, K.K.; Danko, J.C. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Angell, P. [Southwest Research Inst., San Antonio, TX (United States); Dexter, S.C. [Univ. of Delaware, Lewes, DE (United States). Coll. of Marine Studies

    1996-12-01

    Weldments representative of a range of marine structural materials were exposed to a natural marine environment which was known from previous studies to induce microbially influenced corrosion (MIC). The natural environment was at a University of Delaware site on the Delaware Bay, Lewes, Delaware. Companion laboratory control tests were conducted at the University of Tennessee in 0.2 pm filtered Delaware Bay water and in synthetic seawater. The natural and control tests were conducted with weldments in both creviced and non-creviced conditions. Open-circuit Potentials (OCPs) and corrosion rates (polarization-resistance measurements and microscopic examinations) were evaluated for all tests. The weldments studied were: 304L, 316L and AL-6XN stainless steels; HY-80 and HSLA-80 low-alloy steels; Alloy 400 Ni-Cu alloy; 90-10 Cu-Ni alloy; 5086 aluminum alloy; and unalloyed titanium. In the non-creviced condition, ennoblement of the OCP, to varying degrees, relative to the laboratory control tests, occurred for all weldments. Clearly, a microbial effect at the Delaware Bay site was responsible for this ennoblement (higher OCP values). On comparison of corrosion rates in the natural Delaware Bay water with those in the laboratory control tests, it was determined that the microbial influence was one of significant corrosion acceleration for the 304L. 316L, Alloy 400, and 90-10 Cu-Ni weldments, with Alloy 400 experiencing the greatest degree of acceleration. Corrosion acceleration also occurred for the low-alloy steel weldments, HY-80 and HSLA-80, but to a smaller degree. Conversely, the microbial influence resulted in corrosion inhibition for the 5086 aluminum alloy and titanium weldments. For the AL-6XN weldment, the microbial influence produced corrosion inhibition in the non-creviced condition, but corrosion acceleration in the creviced condition.

  1. An unexpected negative influence of light intensity on hydrogen production by dark fermentative bacteria Clostridium beijerinckii.

    Science.gov (United States)

    Zagrodnik, R; Laniecki, M

    2016-01-01

    The role of light intensity on biohydrogen production from glucose by Clostridium beijerinckii, Clostridium acetobutylicum, and Rhodobacter sphaeroides was studied to evaluate the performance and possible application in co-culture fermentation system. The applied source of light had spectrum similar to the solar radiation. The influence of light intensity on hydrogen production in dark process by C. acetobutylicum was negligible. In contrast, dark fermentation by C. beijerinckii bacteria showed a significant decrease (83%) in produced hydrogen at light intensity of 540W/m(2). Here, the redirection of metabolism from acetic and butyric acid formation towards lactic acid was observed. This not yet reported effect was probably caused by irradiation of these bacteria by light within UVA range, which is an important component of the solar radiation. The excessive illumination with light of intensity higher than 200W/m(2) resulted in decrease in hydrogen production with photofermentative bacteria as well. PMID:26602144

  2. Influence of whole-wheat consumption on fecal microbial community structure of obese diabetic mice.

    Science.gov (United States)

    Garcia-Mazcorro, Jose F; Ivanov, Ivan; Mills, David A; Noratto, Giuliana

    2016-01-01

    The digestive tract of mammals and other animals is colonized by trillions of metabolically-active microorganisms. Changes in the gut microbiota have been associated with obesity in both humans and laboratory animals. Dietary modifications can often modulate the obese gut microbial ecosystem towards a more healthy state. This phenomenon should preferably be studied using dietary ingredients that are relevant to human nutrition. This study was designed to evaluate the influence of whole-wheat, a food ingredient with several beneficial properties, on gut microorganisms of obese diabetic mice. Diabetic (db/db) mice were fed standard (obese-control) or whole-wheat isocaloric diets (WW group) for eight weeks; non-obese mice were used as control (lean-control). High-throughput sequencing using the MiSeq platform coupled with freely-available computational tools and quantitative real-time PCR were used to analyze fecal bacterial 16S rRNA gene sequences. Short-chain fatty acids were measured in caecal contents using quantitative high-performance liquid chromatography photo-diode array analysis. Results showed no statistical difference in final body weights between the obese-control and the WW group. The bacterial richness (number of Operational Taxonomic Units) did not differ among the treatment groups. The abundance of Ruminococcaceae, a family containing several butyrate-producing bacteria, was found to be higher in obese (median: 6.9%) and WW-supplemented mice (5.6%) compared to lean (2.7%, p = 0.02, Kruskal-Wallis test). Caecal concentrations of butyrate were higher in obese (average: 2.91 mmol/mg of feces) but especially in WW-supplemented mice (4.27 mmol/mg) compared to lean controls (0.97 mmol/mg), while caecal succinic acid was lower in the WW group compared to obese but especially to the lean group. WW consumption was associated with ∼3 times higher abundances of Lactobacillus spp. compared to both obese and lean control mice. Analysis of weighted Uni

  3. INFLUENCE OF MICROBIAL INOCULANTS ON FEEDING VALUE OF SPENT LENTINULA EDODES SUBSTRATE

    Directory of Open Access Journals (Sweden)

    Yunfu Gu

    2012-01-01

    Full Text Available Sawdust-based Spent Lentinula Edodes Substrate (SLES is an important agricultural waste resource for its’ huge production amount, on the other hand, it is hard to recycling because of the low digestibility. For the purpose of recycling the SLES, a study was conducted to improve the feeding values of SLES via microbial inoculation. The SLES was ensiled with 0.5% (v/w Lactic Acid Bacteria (LAB, Lactobacillus plantarum or 0.5% (v/w yeast (Saccharomyces cerevisiae for 15 days. Four treatments were made included 100% SLES (control, 99% SLES +0.5% LAB (T1, 99% SLES +0.5% yeast (T2 and 99% SLES +0.5% LAB +0.5% yeast (T3. Compared with the raw SLES (not fermentation, 100% SLES (control after ensiling showed higher (p<0.05 pH (5.47 and lower lactic acid production. The addition of microbe to the SLES improved most of the physical parameters, fermentation parameters and microbial populations compared to the control experiments. On the other hand, microbial-blending to SLES decreased most of the chemical parameters except for the Crude Protein (CP. Compared to the raw, ensile fermentation would increase the amino acids and microbial inoculants to the SLES could increase the total amount of amino acids further and the most abundant component of essential-amino acid and non-essential amino acid were valine and glutamate, respectively. Among the four ensile treatments, the impact of the addition of 0.5% LAB and 0.5% yeast (T3 on the SLES storage and feeding value was the greatest one (p<0.05. In conclusion: Microbial inoculation improved ensiling and feeding values of SLES.

  4. Dissolved Organic Carbon Influences Microbial Community Composition and Diversity in Managed Aquifer Recharge Systems

    KAUST Repository

    Li, D.

    2012-07-13

    This study explores microbial community structure in managed aquifer recharge (MAR) systems across both laboratory and field scales. Two field sites, the Taif River (Taif, Saudi Arabia) and South Platte River (Colorado), were selected as geographically distinct MAR systems. Samples derived from unsaturated riverbed, saturated-shallow-infiltration (depth, 1 to 2 cm), and intermediate-infiltration (depth, 10 to 50 cm) zones were collected. Complementary laboratory-scale sediment columns representing low (0.6 mg/liter) and moderate (5 mg/liter) dissolved organic carbon (DOC) concentrations were used to further query the influence of DOC and depth on microbial assemblages. Microbial density was positively correlated with the DOC concentration, while diversity was negatively correlated at both the laboratory and field scales. Microbial communities derived from analogous sampling zones in each river were not phylogenetically significantly different on phylum, class, genus, and species levels, as determined by 16S rRNA gene pyrosequencing, suggesting that geography and season exerted less sway than aqueous geochemical properties. When field-scale communities derived from the Taif and South Platte River sediments were grouped together, principal coordinate analysis revealed distinct clusters with regard to the three sample zones (unsaturated, shallow, and intermediate saturated) and, further, with respect to DOC concentration. An analogous trend as a function of depth and corresponding DOC loss was observed in column studies. Canonical correspondence analysis suggests that microbial classes Betaproteobacteria and Gammaproteobacteria are positively correlated with DOC concentration. Our combined analyses at both the laboratory and field scales suggest that DOC may exert a strong influence on microbial community composition and diversity in MAR saturated zones.

  5. Dust inputs and bacteria influence dissolved organic matter in clear alpine lakes.

    Science.gov (United States)

    Mladenov, N; Sommaruga, R; Morales-Baquero, R; Laurion, I; Camarero, L; Diéguez, M C; Camacho, A; Delgado, A; Torres, O; Chen, Z; Felip, M; Reche, I

    2011-01-01

    Remote lakes are usually unaffected by direct human influence, yet they receive inputs of atmospheric pollutants, dust, and other aerosols, both inorganic and organic. In remote, alpine lakes, these atmospheric inputs may influence the pool of dissolved organic matter, a critical constituent for the biogeochemical functioning of aquatic ecosystems. Here, to assess this influence, we evaluate factors related to aerosol deposition, climate, catchment properties, and microbial constituents in a global dataset of 86 alpine and polar lakes. We show significant latitudinal trends in dissolved organic matter quantity and quality, and uncover new evidence that this geographic pattern is influenced by dust deposition, flux of incident ultraviolet radiation, and bacterial processing. Our results suggest that changes in land use and climate that result in increasing dust flux, ultraviolet radiation, and air temperature may act to shift the optical quality of dissolved organic matter in clear, alpine lakes.

  6. MICROBIAL LOAD AND MULTIPLE DRUG RESISTANCE OF PATHOGENIC BACTERIA ISOLATED FROM FEACES AND BODY SURFACES OF COCKROACHES IN AN URBAN AREA OF SOUTHWESTERN NIGERIA

    Directory of Open Access Journals (Sweden)

    Monsuru Adebayo Adeleke

    2012-06-01

    Full Text Available This study investigates the microbial load and antibiotic susceptibility pattern of pathogenic bacteria isolated from the faeces and body surfaces of cockroaches in Osogbo, Southwestern Nigeria. The cockroaches collected from residential areas and hospital vicinities were screened for microbial load and antibiotic susceptibility pattern using standard protocols. A total of twenty- three microorganisms namely Klebsiella aerogenes, Bacillius cereus, Proteus spp, Staphyloccocus aureus, S. saprophyticus, Enteroccocus faecalis, Staphylococus epididermis, E. coli, Listeria monoctogene, Proteus mirabilis, Citrobacter species, Pseudomonas aeruginosa, Psuedomonas species, Seretia mensence, Candida albicans, Candida spp., Aspergilius spp., A. flavus, A. fumigates, Mucor species and Penicilium species were isolated. The microbial load of the microorganisms was significantly higher in the isolates from hospital as compared with the residential area (p<0.05 with the exception of Canidida species, Mucor and Penicillium which had higher or equal microbial load at the residential areas. All the pathogenic bacteria isolated had multiple resistance to antibiotics most importantly, Ampicillin, Augumentin, Amoxicillin and Septrin (30μg. Efforts geared towards controlling the insects will be indispensable in curbing the wide spread of multi-drug resistant pathogens in the study area.

  7. Extracellular Electron Transfer from Aerobic Bacteria to Au-Loaded TiO2 Semiconductor without Light: A New Bacteria-Killing Mechanism Other than Localized Surface Plasmon Resonance or Microbial Fuel Cells.

    Science.gov (United States)

    Wang, Guomin; Feng, Hongqing; Gao, Ang; Hao, Qi; Jin, Weihong; Peng, Xiang; Li, Wan; Wu, Guosong; Chu, Paul K

    2016-09-21

    Titania loaded with noble metal nanoparticles exhibits enhanced photocatalytic killing of bacteria under light illumination due to the localized surface plasmon resonance (LSPR) property. It has been shown recently that loading with Au or Ag can also endow TiO2 with the antibacterial ability in the absence of light. In this work, the antibacterial mechanism of Au-loaded TiO2 nanotubes (Au@TiO2-NT) in the dark environment is studied, and a novel type of extracellular electron transfer (EET) between the bacteria and the surface of the materials is observed to cause bacteria death. Although the EET-induced bacteria current is similar to the LSPR-related photocurrent, the former takes place without light, and no reactive oxygen species (ROS) are produced during the process. The EET is also different from that commonly attributed to microbial fuel cells (MFC) because it is dominated mainly by the materials' surface, but not the bacteria, and the environment is aerobic. EET on the Au@TiO2-NT surface kills Staphylococcus aureus, but if it is combined with special MFC bacteria, the efficiency of MFC may be improved significantly.

  8. 硫酸盐还原菌的微生物防治%Microbial Control of Sulfate-reducing Bacteria

    Institute of Scientific and Technical Information of China (English)

    赵波; 贺承祖; 李冬菊

    2012-01-01

    Sulfate -Reducing Bacteria (SRB) is a group of prokaryotes which are capable of reducing the sulfate to sulfide under anaerobic condition with organic substance as electron donors. Sulfide production by SRB is a major concern for the petroleum industry, since it is toxic and corrosive, and causes plugging due to the formation of insoluble iron suliides. Biocides are widely used to control SRB growth. Experience has shown that biocides are expensive and toxic to humans and environment, but more importantly, biocidal treatments are not always effective, since the biological film will reduce biocidal effect and SRB will eventually develop the resistance to biocides. Various microbial methods for inhibiting SRB have been proposed for different treatment purposes as fallows : (1) application of nitrate to activate Nitrate Reducing Bacteria (NRB) for inhibiting the growth of sulfate reducing bacteria through biological competition; (2) application of Sulfide Oxidizing Bacteria (SOB) for removing hydrogen sulfide through biological oxidation; (3) application of Brevibacillus brevis for inhibiting SRB through the produced antagonistic substance; (4) application of phage for killing SRB. At present, application of method one in oil field and application of method two in sewage treatment have entered the industrial tests, both method three and method four are still in the basic research stage. These methods have great application prospect, however there are many problems to be solved. The analysis on these problems is carried on.%硫酸盐还原菌(SRB)是一类能在厌氧条件下以有机物为电子供体,将硫酸盐还原为硫化物的原核微生物.SRB产生的硫化物具有毒性和腐蚀性,其腐蚀产物硫化铁会堵塞地层,历来为环保和石油工业所关注.杀菌剂虽广泛用于抑制SRB生长;但杀菌剂不但价格高,对人体和环境有毒害作用,而且由于生物膜会降低杀菌效果和SRB会产生抗药性,难以获得满意的效

  9. Comparison of factors influencing trichloroethylene degradation by toluene-oxidizing bacteria.

    OpenAIRE

    Leahy, J G; Byrne, A M; Olsen, R H

    1996-01-01

    The degradation of trichloroethylene (TCE) by toluene-oxidizing bacteria has been extensively studied, and yet the influence of environmental conditions and physiological characteristics of individual strains has received little attention. To consider these effects, the levels of TCE degradation by strains distinguishable on the basis of toluene and nitrate metabolism were compared under aerobic or hypoxic conditions in the presence and absence of nitrate and an exogenous electron donor, lact...

  10. The influences of fish infusion broth on the biogenic amines formation by lactic acid bacteria

    OpenAIRE

    Esmeray Küley; Fatih Özogul; Esra Balikçi; Mustafa Durmus; Deniz Ayas

    2013-01-01

    The influences of fish infusion decarboxylase broth (IDB) on biogenic amines (BA) formation by lactic acid bacteria (LAB) were investigated. BA productions by single LAB strains were tested in five different fish (anchovy, mackerel, white shark, sardine and gilthead seabream) IDB. The result of the study showed that significant differences in ammonia (AMN) and BA production were observed among the LAB strains in fish IDB (p < 0.05). The highest AMN and TMA production by LAB strains were obser...

  11. The influence of hydrogeological disturbance and mining on coal seam microbial communities.

    Science.gov (United States)

    Raudsepp, M J; Gagen, E J; Evans, P; Tyson, G W; Golding, S D; Southam, G

    2016-03-01

    The microbial communities present in two underground coal mines in the Bowen Basin, Queensland, Australia, were investigated to deduce the effect of pumping and mining on subsurface methanogens and methanotrophs. The micro-organisms in pumped water from the actively mined areas, as well as, pre- and post-mining formation waters were analyzed using 16S rRNA gene amplicon sequencing. The methane stable isotope composition of Bowen Basin coal seam indicates that methanogenesis has occurred in the geological past. More recently at the mine site, changing groundwater flow dynamics and the introduction of oxygen in the subsurface has increased microbial biomass and diversity. Consistent with microbial communities found in other coal seam environments, pumped coal mine waters from the subsurface were dominated by bacteria belonging to the genera Pseudomonas and the family Rhodocyclaceae. These environments and bacterial communities supported a methanogen population, including Methanobacteriaceae, Methanococcaceae and Methanosaeta. However, one of the most ubiquitous micro-organisms in anoxic coal mine waters belonged to the family 'Candidatus Methanoperedenaceae'. As the Archaeal family 'Candidatus Methanoperedenaceae' has not been extensively defined, the one studied species in the family is capable of anaerobic methane oxidation coupled to nitrate reduction. This introduces the possibility that a methane cycle between archaeal methanogenesis and methanotrophy may exist in the anoxic waters of the coal seam after hydrogeological disturbance. PMID:26541089

  12. A generic transport-reactive model for simulating microbially influenced mineral precipitation in porous medium

    OpenAIRE

    Zhou, J.; Van Turnhout, A.G.; Heimovaara, T.J.; Afanasyev, M.

    2015-01-01

    The spatial and temporal distribution of precipitated minerals is one of the key factors governing various processes in the sub-surface environment, including microbially influenced corrosion (MIC) (Huang, 2002), bio-cementation (van Paassen et al., 2010) and sediment diagenesis (Paraska et al., 2014). The mineral precipitation not only affects the overall reaction network (Konhauser, 1997), but is also physically interconnected with the transport properties of the subsurface environment (Pin...

  13. Microbially influenced corrosion communities associated with fuel-grade ethanol environments

    OpenAIRE

    Williamson, Charles H. D.; Jain, Luke A.; Mishra, Brajendra; Olson, David L.; Spear, John R.

    2015-01-01

    Microbially influenced corrosion (MIC) is a costly problem that impacts hydrocarbon production and processing equipment, water distribution systems, ships, railcars, and other types of metallic infrastructure. In particular, MIC is known to cause considerable damage to hydrocarbon fuel infrastructure including production, transportation, and storage systems, often times with catastrophic environmental contamination results. As the production and use of alternative fuels such as fuel-grade eth...

  14. Characterization of exoelectrogenic bacteria enterobacter strains isolated from a microbial fuel cell exposed to copper shock load.

    Directory of Open Access Journals (Sweden)

    Cuijie Feng

    Full Text Available Microorganisms capable of generating electricity in microbial fuel cells (MFCs have gained increasing interest. Here fourteen exoelectrogenic bacterial strains were isolated from the anodic biofilm in an MFC before and after copper (Cu shock load by Hungate roll-tube technique with solid ferric (III oxide as an electron acceptor and acetate as an electron donor. Phylogenetic analysis of the 16S rRNA gene sequences revealed that they were all closely related to Enterobacter ludwigii DSM 16688T within the Enterobacteriaceae family, although these isolated bacteria showed slightly different morphology before and after Cu shock load. Two representative strains R2B1 (before Cu shock load and B4B2 (after Cu shock load were chosen for further analysis. B4B2 is resistant to 200 mg L-1 of Cu(II while R2B1 is not, which indicated the potential selection of the Cu shock load. Raman analysis revealed that both R2B1 and B4B2 contained c-type cytochromes. Cyclic voltammetry measurements revealed that strain R2B1 had the capacity to transfer electrons to electrodes. The experimental results demonstrated that strain R2B1 was capable of utilizing a wide range of substrates, including Luria-Bertani (LB broth, cellulose, acetate, citrate, glucose, sucrose, glycerol and lactose to generate electricity, with the highest current density of 440 mA·m-2 generated from LB-fed MFC. Further experiments indicated that the bacterial cell density had potential correlation with the current density.

  15. Survival of bacteria in nuclear waste buffer materials. The influence of nutrients, temperature and water activity

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, K.; Motamedi, M. [Goeteborg Univ. (Sweden). Dept. of General and Marine Microbiology; Karnland, O. [Clay Technology AB, Lund (Sweden)

    1995-12-01

    The concept of deep geological disposal of spent fuel is common to many national nuclear waste programs. Long-lived radioactive waste will be encapsulated in canisters made of corrosion resistant materials e.g. copper and buried several hundred meters below ground in a geological formation. Different types of compacted bentonite clay, or mixtures with sand, will be placed as a buffer around the waste canisters. A major concern for the performance of the canisters is that sulphate-reducing bacteria (SRB) may be present in the clay and induce corrosion by production of hydrogen sulphide. This report presents data on viable counts of SRB in the bedrock of Aespoe hard rock laboratory. A theoretical background on the concept water activity is given, together with basic information about SRB. Some results on microbial populations from a full scale buffer test in Canada is presented. These results suggested water activity to be a strong limiting factor for survival of bacteria in compacted bentonite. As a consequence, experiments were set up to investigate the effect from water activity on survival of SRB in bentonite. Here we show that survival of SRB in bentonite depends on the availability of water and that compacting a high quality bentonite to a density of 2.0 g/cm{sup 3}, corresponding to a water activity (a{sub w}) of 0.96, prevented SRB from surviving in the clay. 24 refs.

  16. Survival of bacteria in nuclear waste buffer materials. The influence of nutrients, temperature and water activity

    International Nuclear Information System (INIS)

    The concept of deep geological disposal of spent fuel is common to many national nuclear waste programs. Long-lived radioactive waste will be encapsulated in canisters made of corrosion resistant materials e.g. copper and buried several hundred meters below ground in a geological formation. Different types of compacted bentonite clay, or mixtures with sand, will be placed as a buffer around the waste canisters. A major concern for the performance of the canisters is that sulphate-reducing bacteria (SRB) may be present in the clay and induce corrosion by production of hydrogen sulphide. This report presents data on viable counts of SRB in the bedrock of Aespoe hard rock laboratory. A theoretical background on the concept water activity is given, together with basic information about SRB. Some results on microbial populations from a full scale buffer test in Canada is presented. These results suggested water activity to be a strong limiting factor for survival of bacteria in compacted bentonite. As a consequence, experiments were set up to investigate the effect from water activity on survival of SRB in bentonite. Here we show that survival of SRB in bentonite depends on the availability of water and that compacting a high quality bentonite to a density of 2.0 g/cm3, corresponding to a water activity (aw) of 0.96, prevented SRB from surviving in the clay. 24 refs

  17. Influence of different anoxic time exposures on active biomass, protozoa and filamentous bacteria in activated sludge.

    Science.gov (United States)

    Rodriguez-Perez, S; Fermoso, F G; Arnaiz, C

    2016-01-01

    Medium-sized wastewater treatment plants are considered too small to implement anaerobic digestion technologies and too large for extensive treatments. A promising option as a sewage sludge reduction method is the inclusion of anoxic time exposures. In the present study, three different anoxic time exposures of 12, 6 and 4 hours have been studied to reduce sewage sludge production. The best anoxic time exposure was observed under anoxic/oxic cycles of 6 hours, which reduced 29.63% of the biomass production compared with the oxic control conditions. The sludge under different anoxic time exposures, even with a lower active biomass concentration than the oxic control conditions, showed a much higher metabolic activity than the oxic control conditions. Microbiological results suggested that both protozoa density and abundance of filamentous bacteria decrease under anoxic time exposures compared to oxic control conditions. The anoxic time exposures 6/6 showed the highest reduction in both protozoa density, 37.5%, and abundance of filamentous bacteria, 41.1%, in comparison to the oxic control conditions. The groups of crawling ciliates, carnivorous ciliates and filamentous bacteria were highly influenced by the anoxic time exposures. Protozoa density and abundance of filamentous bacteria have been shown as promising bioindicators of biomass production reduction. PMID:27508364

  18. Influence of Biological Macromolecules and Aquatic Chemistries on the Inhibition of Nitrifying Bacteria by Silver Nanoparticles

    Science.gov (United States)

    Radniecki, T. S.; Anderson, J. W.; Schneider, M. C.; Stankus, D. P.; Nason, J. A.; Semprini, L.

    2010-12-01

    The use of silver nanoparticles (Ag-NP) as a broad spectrum biocide in a wide range of consumer goods has grown exponentially since 2006 (1), which may result in an increased release of Ag-NP into wastewater streams and ultimately the receiving bodies of water. Ammonia oxidizing bacteria (AOB) play a critical role in the global nitrogen cycle through the oxidation of ammonia (NH3) to nitrite (NO2-) and are widely considered to be the most sensitive microbial fauna in the environment being readily inhibited by contaminants, including Ag-NP (2). This research used physiological techniques in combination with physical/chemical assays to characterize the inhibition of Nitrosomonas europaea, the model AOB, by silver ions (Ag+), 3-5 nm Ag-NP, 20 nm Ag-NP and 80 nm Ag-NP under a variety of aqueous chemistries. In addition, the stability of Ag-NP suspensions was examined under a variety of aqueous chemistries including in the presences of divalent cations, chloride anions, natural organic matter (NOM), proteins (BSA) and lipopolysaccharides (alginate). Using the stable Ag-NP/test media suspensions, N. europaea was found to be extremely sensitive to Ag+, 3-5 nm Ag-NP, 20 nm Ag-NP and 80 nm Ag-NP with concentrations of 0.1, 0.12, 0.5 and 1.5 ppm, respectively, resulting in a 50% decrease in nitrification rates. The inhibition was correlated with the amount of Ag+ released into solution. It is suspected that the inhibition observed from Ag-NP exposure is caused by the liberated Ag+. The aquatic chemistry of the test media was found to have a profound influence on the stability of Ag-NP suspensions. The presence of Ag ligands (e.g. EDTA and Cl-) reduced toxicity of Ag-NP through the formation of Ag-ligand complexes with the liberated Ag+. The presence of divalent cations (e.g. Ca2+ or Mg2+) resulted in the rapid aggregation of Ag-NP leading to a decrease in Ag+ liberation and thus a decrease in N. europaea inhibition. The presence of 5 ppm NOM resulted in a highly stable Ag

  19. ADAPTATION OF AQUIFER MICROBIAL COMMUNITIES TO THE BIODEGRADATION OF XENOBIOTIC COMPOUNDS: INFLUENCE OF SUBSTRATE CONCENTRATION AND PREEXPOSURE

    Science.gov (United States)

    Studies were conducted to examine the adaptation response of aquifer microbial communities to xenobiotic compounds and the influence of chemical preexposure in the laboratory and in situ on adaptation. Adaptation and biodegradation were assessed as mineralization and cellular inc...

  20. [Influence of Submerged Plants on Microbial Community Structure in Sediment of Hongze Lake].

    Science.gov (United States)

    Zhang, Ding-yu; Zhang, Ting-xi; Dong, Dan-ping; Li, De-fang; Wang, Guo-xiang

    2016-05-15

    Phospholipid fatty acids (PLFAs) method was applied to analyze the influence of submerged plants on sediment microbial community structure, in order to investigate the changes of sediment microbial community structure for different kinds of the submerged plants in different growth periods. Particularly, Potamogeton crispus L., Potamogeton pectinatus L and the mixed group were chosen as the typical submerged plants in Hongze Lake for investigation in this paper. The results indicated that the change of total PLFAs in different periods was significant, on the contrary, the PLFA change for different groups in the same period was insignificant. The values of G⁺ PLFA/G⁻ PLFA in the submerged plant group were also highly related to the different growth periods, which demonstrated that the root function of the submerged plant had a severe impact on the microbial community in sediment. Furthermore, some environmental factors, such as Temperature, pH, TOC and DO, were correlated to characteristic phospholipid of PLFAs in sediment, which means the environmental factors could also affect the microbial community structure.

  1. Carcass mass has little influence on the structure of gravesoil microbial communities.

    Science.gov (United States)

    Weiss, Sophie; Carter, David O; Metcalf, Jessica L; Knight, Rob

    2016-01-01

    Little is known about how variables, such as carcass mass, affect the succession pattern of microbes in soils during decomposition. To investigate the effects of carcass mass on the soil microbial community, soils associated with swine (Sus scrofa domesticus) carcasses of four different masses were sampled until the 15th day of decomposition during the month of June in a pasture near Lincoln, Nebraska. Soils underneath swine of 1, 20, 40, and 50 kg masses were investigated in triplicate, as well as control sites not associated with a carcass. Soil microbial communities were characterized by sequencing the archaeal, bacterial (16S), and eukaryotic (18S) rRNA genes in soil samples. We conclude that time of decomposition was a significant influence on the microbial community, but carcass mass was not. The gravesoil associated with 1 kg mass carcasses differs most compared to the gravesoil associated with other carcass masses. We also identify the 15 most abundant bacterial and eukaryotic taxa, and discuss changes in their abundance as carcass decomposition progressed. Finally, we show significant decreases in alpha diversity for carcasses of differing mass in pre-carcass rupture (days 0, 1, 2, 4, 5, and 6 postmortem) versus post-carcass rupture (days 9 and 15 postmortem) microbial communities.

  2. The Impact of Microbially Influenced Corrosion on Spent Nuclear Fuel and Storage Life

    Energy Technology Data Exchange (ETDEWEB)

    J. H. Wolfram; R. E. Mizia; R. Jex; L. Nelson; K. M. Garcia

    1996-10-01

    A study was performed to evaluate if microbial activity could be considered a threat to spent nuclear fuel integrity. The existing data regarding the impact of microbial influenced corrosion (MIC) on spent nuclear fuel storage does not allow a clear assessment to be made. In order to identify what further data are needed, a literature survey on MIC was accomplished with emphasis on materials used in nuclear fuel fabrication, e.g., A1, 304 SS, and zirconium. In addition, a survey was done at Savannah River, Oak Ridge, Hanford, and the INEL on the condition of their wet storage facilities. The topics discussed were the SNF path forward, the types of fuel, ramifications of damaged fuel, involvement of microbial processes, dry storage scenarios, ability to identify microbial activity, definitions of water quality, and the use of biocides. Information was also obtained at international meetings in the area of biological mediated problems in spent fuel and high level wastes. Topics dis cussed included receiving foreign reactor research fuels into existing pools, synergism between different microbes and other forms of corrosion, and cross contamination.

  3. The Impact of Microbially Influenced Corrosion on Spent Nuclear Fuel and Storage Life

    International Nuclear Information System (INIS)

    A study was performed to evaluate if microbial activity could be considered a threat to spent nuclear fuel integrity. The existing data regarding the impact of microbial influenced corrosion (MIC) on spent nuclear fuel storage does not allow a clear assessment to be made. In order to identify what further data are needed, a literature survey on MIC was accomplished with emphasis on materials used in nuclear fuel fabrication, e.g., A1, 304 SS, and zirconium. In addition, a survey was done at Savannah River, Oak Ridge, Hanford, and the INEL on the condition of their wet storage facilities. The topics discussed were the SNF path forward, the types of fuel, ramifications of damaged fuel, involvement of microbial processes, dry storage scenarios, ability to identify microbial activity, definitions of water quality, and the use of biocides. Information was also obtained at international meetings in the area of biological mediated problems in spent fuel and high level wastes. Topics dis cussed included receiving foreign reactor research fuels into existing pools, synergism between different microbes and other forms of corrosion, and cross contamination

  4. Influence of DNA extraction on oral microbial profiles obtained via 16S rRNA gene sequencing

    Directory of Open Access Journals (Sweden)

    Loreto Abusleme

    2014-04-01

    Full Text Available Background and objective: The advent of next-generation sequencing has significantly facilitated characterization of the oral microbiome. Despite great efforts in streamlining the processes of sequencing and data curation, upstream steps required for amplicon library generation could still influence 16S rRNA gene-based microbial profiles. Among upstream processes, DNA extraction is a critical step that could represent a great source of bias. Accounting for bias introduced by extraction procedures is important when comparing studies that use different methods. Identifying the method that best portrays communities is also desirable. Accordingly, the aim of this study was to evaluate bias introduced by different DNA extraction procedures on oral microbiome profiles. Design: Four DNA extraction methods were tested on mock communities consisting of seven representative oral bacteria. Additionally, supragingival plaque samples were collected from seven individuals and divided equally to test two commonly used DNA extraction procedures. Amplicon libraries of the 16S rRNA gene were generated and sequenced via 454-pyrosequencing. Results: Evaluation of mock communities revealed that DNA yield and bacterial species representation varied with DNA extraction methods. Despite producing the lowest yield of DNA, a method that included bead beating was the only protocol capable of detecting all seven species in the mock community. Comparison of the performance of two commonly used methods (crude lysis and a chemical/enzymatic lysis+column-based DNA isolation on plaque samples showed no effect of extraction protocols on taxa prevalence but global community structure and relative abundance of individual taxa were affected. At the phylum level, the latter method improved the recovery of Actinobacteria, Bacteroidetes, and Spirochaetes over crude lysis. Conclusion: DNA extraction distorts microbial profiles in simulated and clinical oral samples, reinforcing the

  5. Electrochemical characterization of direct electron uptake in electrical microbially influenced corrosion of iron by the lithoautotrophic SRB Desulfopila corrodens strain IS4

    International Nuclear Information System (INIS)

    Highlights: •direct electron uptake from cathodes by lithotrophic sulfate-reducing bacteria. •graphite and germanium cathodes serving as an electron donor for corrosive SRB. •stimulation of microbial activity in a lithoautotrophic SRB at –0.4 V vs. SHE. •direct electron transfer in electrical microbially influenced corrosion of iron. •c-type cytochromes involved in direct electron transfer mechanism of electrical MIC. -- Abstract: Corrosion of iron infrastructure in anoxic environments is commonly ascribed to the metabolic activity of sulfate-reducing bacteria (SRB), which can influence electrochemical processes on the metallic surface. The present study characterizes electron transfer processes at the electrode/microorganism interface of the specialized lithoautotrophic SRB Desulfopila corrodens strain IS4 that is capable of taking up electrons directly from elemental iron, thereby leading to severe corrosion. Electrochemical analysis of the highly corrosive SRB is performed in bio-electrochemical cells operated with artificial seawater under anoxic conditions, complemented by infrared spectroelectrochemical analysis and environmental SEM observations. In order to provide clear insights into electron transfer processes, sterile controls and a non-corrosive hydrogenotrophic control strain are analyzed in parallel. Remarkably, the electron uptake from electrodes by D. corrodens strain IS4 is not restricted to iron serving as the sole electron donor for the microbial metabolism, but instead proceeds also on graphite and doped germanium cathodes. Consequently, a well-defined electrochemical analysis of the electron uptake mechanism is possible, since corrosion precipitates typically observed on iron electrodes are absent on both of the other cathode materials. Direct electron transfer in the absence of artificial electron mediators is achieved at a potential of −0.4 V vs. SHE under neutral conditions. Electrochemical and infrared spectroelectrochemical

  6. Influence of microbial community structure of seed sludge on the properties of aerobic nitrifying granules.

    Science.gov (United States)

    Song, Zhiwei; Li, Ting; Wang, Qiuxu; Pan, Yu; Li, Lixin

    2015-09-01

    In order to evaluate the influence of microbial community structure of seed sludge on the properties of aerobic nitrifying granules, these granules were cultivated with different seed sludge, and the variation of microbial community and dominant bacterial groups that impact the nitrogen removal efficiency of the aerobic nitrifying granules were analyzed and identified using 16s rDNA sequence and denaturing gradient gel electrophoresis (DGGE) profiles. The results presented here demonstrated that the influence of the community structure of seed sludge on the properties of aerobic nitrifying granules was remarkable, and the granules cultivated by activated sludge from a beer wastewater treatment plant showed better performance, with a stable sludge volume index (SVI) value of 20mL/g, high extracellular polymeric substance (EPS) content of 183.3mg/L, high NH4(+)-N removal rate of 89.42% and abundant microbial population with 10 dominant bacterial groups. This indicated that activated sludge with abundant communities is suitable for use as seed sludge in culturing aerobic nitrifying granules. PMID:26354703

  7. Changes in soil microbial community structure influenced by agricultural management practices in a mediterranean agro-ecosystem.

    Directory of Open Access Journals (Sweden)

    Fuensanta García-Orenes

    Full Text Available Agricultural practices have proven to be unsuitable in many cases, causing considerable reductions in soil quality. Land management practices can provide solutions to this problem and contribute to get a sustainable agriculture model. The main objective of this work was to assess the effect of different agricultural management practices on soil microbial community structure (evaluated as abundance of phospholipid fatty acids, PLFA. Five different treatments were selected, based on the most common practices used by farmers in the study area (eastern Spain: residual herbicides, tillage, tillage with oats and oats straw mulching; these agricultural practices were evaluated against an abandoned land after farming and an adjacent long term wild forest coverage. The results showed a substantial level of differentiation in the microbial community structure, in terms of management practices, which was highly associated with soil organic matter content. Addition of oats straw led to a microbial community structure closer to wild forest coverage soil, associated with increases in organic carbon, microbial biomass and fungal abundances. The microbial community composition of the abandoned agricultural soil was characterised by increases in both fungal abundances and the metabolic quotient (soil respiration per unit of microbial biomass, suggesting an increase in the stability of organic carbon. The ratio of bacteria:fungi was higher in wild forest coverage and land abandoned systems, as well as in the soil treated with oat straw. The most intensively managed soils showed higher abundances of bacteria and actinobacteria. Thus, the application of organic matter, such as oats straw, appears to be a sustainable management practice that enhances organic carbon, microbial biomass and activity and fungal abundances, thereby changing the microbial community structure to one more similar to those observed in soils under wild forest coverage.

  8. Changes in soil microbial community structure influenced by agricultural management practices in a mediterranean agro-ecosystem.

    Science.gov (United States)

    García-Orenes, Fuensanta; Morugán-Coronado, Alicia; Zornoza, Raul; Cerdà, Artemi; Scow, Kate

    2013-01-01

    Agricultural practices have proven to be unsuitable in many cases, causing considerable reductions in soil quality. Land management practices can provide solutions to this problem and contribute to get a sustainable agriculture model. The main objective of this work was to assess the effect of different agricultural management practices on soil microbial community structure (evaluated as abundance of phospholipid fatty acids, PLFA). Five different treatments were selected, based on the most common practices used by farmers in the study area (eastern Spain): residual herbicides, tillage, tillage with oats and oats straw mulching; these agricultural practices were evaluated against an abandoned land after farming and an adjacent long term wild forest coverage. The results showed a substantial level of differentiation in the microbial community structure, in terms of management practices, which was highly associated with soil organic matter content. Addition of oats straw led to a microbial community structure closer to wild forest coverage soil, associated with increases in organic carbon, microbial biomass and fungal abundances. The microbial community composition of the abandoned agricultural soil was characterised by increases in both fungal abundances and the metabolic quotient (soil respiration per unit of microbial biomass), suggesting an increase in the stability of organic carbon. The ratio of bacteria:fungi was higher in wild forest coverage and land abandoned systems, as well as in the soil treated with oat straw. The most intensively managed soils showed higher abundances of bacteria and actinobacteria. Thus, the application of organic matter, such as oats straw, appears to be a sustainable management practice that enhances organic carbon, microbial biomass and activity and fungal abundances, thereby changing the microbial community structure to one more similar to those observed in soils under wild forest coverage.

  9. Microbial interactions with naturally occurring hydrophobic sediments: Influence on sediment and associated contaminant mobility.

    Science.gov (United States)

    Droppo, I G; Krishnappan, B G; Lawrence, J R

    2016-04-01

    The erosion, transport and fate of sediments and associated contaminants are known to be influenced by both particle characteristics and the flow dynamics imparted onto the sediment. The influential role of bitumen containing hydrophobic sediments and the microbial community on sediment dynamics are however less understood. This study links an experimental evaluation of sediment erosion with measured sediment-associated contaminant concentrations and microbial community analysis to provide an estimate of the potential for sediment to control the erosion, transport and fate of contaminants. Specifically the paper addresses the unique behaviour of hydrophobic sediments and the role that the microbial community associated with hydrophobic sediment may play in the transport of contaminated sediment. Results demonstrate that the hydrophobic cohesive sediment demonstrates unique transport and particle characteristics (poor settling and small floc size). Biofilms were observed to increase with consolidation/biostabilization times and generated a unique microbial consortium relative to the eroded flocs. Natural oil associated with the flocs appeared to be preferentially associated with microbial derived extracellular polymeric substances. While PAHs and naphthenic acid increased with increasing shear (indicative of increasing loads), they tended to decrease with consolidation/biostabilization (CB) time at similar shears suggesting a chemical and/or biological degradation. PAH and napthenic acid degrading microbes decreased with time as well, which may suggest that there was a reduced pool of PAHs and naphthenic acids available resulting in their die off. This study emphasizes the importance that any management strategies and operational assessments for the protection of human and aquatic health incorporate the sediment (suspended and bed sediment) and biological (biofilm) compartments and the energy dynamics within the system in order to better predict contaminant

  10. Physicochemical properties influencing denitrification rate and microbial activity in denitrification bioreactors

    Science.gov (United States)

    Schmidt, C. A.

    2012-12-01

    The use of N-based fertilizer will need to increase to meet future demands, yet existing applications have been implicated as the main source of coastal eutrophication and hypoxic zones. Producing sufficient crops to feed a growing planet will require efficient production in combination with sustainable treatment solutions. The long-term success of denitrification bioreactors to effectively remove nitrate (NO¬3), indicates this technology is a feasible treatment option. Assessing and quantifying the media properties that affect NO¬3 removal rate and microbial activity can improve predictions on bioreactor performance. It was hypothesized that denitrification rates and microbial biomass would be correlated with total C, NO¬3 concentration, metrics of organic matter quality, media surface area and laboratory measures of potential denitrification rate. NO¬3 removal rates and microbial biomass were evaluated in mesocosms filled with different wood treatments and the unique influence of these predictor variables was determined using a multiple linear regression analysis. NO3 reduction rates were independent of NO¬3 concentration indicating zero order reaction kinetics. Temperature was strongly correlated with denitrification rate (r2=0.87; Q10=4.7), indicating the variability of bioreactor performance in differing climates. Fiber quality, and media surface area were strong (R>0.50), unique predictors of rates and microbial biomass, although C:N ratio and potential denitrification rate did not predict actual denitrification rate or microbial biomass. Utilizing a stepwise multiple linear regression, indicates that the denitrification rate can be effectively (r2=0.56;pbioreactors to achieve significant N load reductions in large watersheds. The nitrate reduction rate as a function of groundwater temperature for all treatments. Correlations between nitrate reduction rate and properties of carbon media;

  11. Niche distribution and influence of environmental parameters in marine microbial communities: a systematic review

    Directory of Open Access Journals (Sweden)

    Felipe H. Coutinho

    2015-06-01

    Full Text Available Associations between microorganisms occur extensively throughout Earth’s oceans. Understanding how microbial communities are assembled and how the presence or absence of species is related to that of others are central goals of microbial ecology. Here, we investigate co-occurrence associations between marine prokaryotes by combining 180 new and publicly available metagenomic datasets from different oceans in a large-scale meta-analysis. A co-occurrence network was created by calculating correlation scores between the abundances of microorganisms in metagenomes. A total of 1,906 correlations amongst 297 organisms were detected, segregating them into 11 major groups that occupy distinct ecological niches. Additionally, by analyzing the oceanographic parameters measured for a selected number of sampling sites, we characterized the influence of environmental variables over each of these 11 groups. Clustering organisms into groups of taxa that have similar ecology, allowed the detection of several significant correlations that could not be observed for the taxa individually.

  12. Changes in the structure of the microbial community under the influence of oil and radioactive pollution

    Science.gov (United States)

    Stepanov, A. L.; Tsvetnova, O. B.; Panikov, S. N.

    2012-12-01

    Different variants of combined radioactive and oil pollution were simulated in a series of model experiments with soils contaminated with radioactive materials. In the soils with a 137Cs pollution density of 5395.5 kBq, the number of Aeromonas, Pseudomonas, and Rhodococcus representatives decreased, and the number of mycobacteria and fungi increased. The pollution of the soils with diesel fuel with up to 5 mL/100 g soil is accompanied by raising the number of hydrocarbon-oxidizing microorganisms; it eliminates to some extent the negative influence of the radionuclides on the soil microbial community approaching the soil to its initial or background state. The high soil pollution with diesel fuel (30 mL/100 g) leads to a decrease in the population of the microbial community and the biological activity. In the growing of plants, the negative effect of the combined radioactive and oil pollution on the biological activity manifests itself less contrastingly.

  13. Risk assessment of microbially-influenced corrosion in industrial plant; Apprehension des risques de biocorrosion dans les installations industrielles

    Energy Technology Data Exchange (ETDEWEB)

    Pritchard, A.M. [Corrosion and Fouling Consultancy, Oxford (United Kingdom)

    2002-07-01

    Risk management is a vital function for managers in industry today and is concerned with avoiding or minimising the harm from potential accidents or incidents. The harm, which may be physical or financial, or both, can be represented as a sum of the product of hazards and the associated risks. Hazards can include substances, machines, methods of work and other aspects of work organisation. Risk expresses the likelihood that the harm from a particular hazard is realised. In overall risk assessment both the risk and the severity or impact of the harm must be assessed. Once the assessment has been made, the process of risk management is undertaken to eradicate or minimise the harm from each and all of the identified risks. The mechanism that links hazards and the harm that they cause is often clear and well-established. However, this is not the case for Microbially Influenced Corrosion (MIC), which has recently been defined by members of a network of European specialists (BRITE-EURAM Network on Microbiologically Influenced Corrosion of Industrial Materials BRRT-CT98-5084) as 'the influence of microorganisms on the kinetics of corrosion processes of metals, mineral and synthetic materials, caused by microorganisms adhering to the corroding interface (usually called 'bio-films'). A prerequisite for MIC is the presence of microorganisms. If MIC is based on their activity, (i) water, (ii) energy source, (iii) carbon source, (iv) electron donator, and (v) electron acceptor are required'. It is clearly a complex process, which is further complicated by the range of microorganisms, mainly bacteria, that are involved. The mechanisms of MIC are relatively poorly understood. The simple presence of microorganisms in a wide range of systems does not generally give rise to corrosion. Other approaches have to be investigated as a means of assessing the risk. (author)

  14. Influences of hydraulic loading rate on SVOC removal and microbial community structure in drinking water treatment biofilters.

    Science.gov (United States)

    Zhang, Xu-Xiang; Zhang, Zong-Yao; Ma, Li-Ping; Liu, Ning; Wu, Bing; Zhang, Yan; Li, Ai-Min; Cheng, Shu-Pei

    2010-06-15

    Six biofilters were used for advanced treatment of Yangtze River source water to investigate the effects of hydraulic loading rate (HLR) on pollutant removal and microbial community. HLR was found to exert significant influences on the removal efficiency of the conventional pollutants and 24 detectable semivolatile organic compounds (SVOCs). More than 85% of chemical oxygen demand and assimilable organic carbon was removed at the optimal HLR of 3.0 m h(-1). With the increase of HLR, SVOC removal showed a decreasing trend. Di-n-butyl phthalate and bis(2-ethylhexyl)phthalate, two main SVOCs in the source water, had the highest removals of 71.2% and 84.4%, respectively. Nearly 65% of 2,6-dinitrotoluene and 80% of isophorone were removed at the lowest HLR. Phylogenetic analysis showed that Escherichia coli, Shigella sp., E. fergusonii and Firmicutes bacteria predominated in the bioreactors. The dominance of E. coli in the low-HLR biofilters might contribute greatly to the high SVOC removal.

  15. Giardia duodenalis-induced alterations of commensal bacteria kill Caenorhabditis elegans: a new model to study microbial-microbial interactions in the gut

    OpenAIRE

    Gerbaba, Teklu K.; Gupta, Pratyush; Rioux, Kevin; Hansen, Dave; Buret, Andre G

    2015-01-01

    Giardia duodenalis is the most common cause of parasitic diarrhea worldwide and a well-established risk factor for postinfectious irritable bowel syndrome. We hypothesized that Giardia-induced disruptions in host-microbiota interactions may play a role in the pathogenesis of giardiasis and in postgiardiasis disease. Functional changes induced by Giardia in commensal bacteria and the resulting effects on Caenorhabditis elegans were determined. Although Giardia or bacteria alone did not affect ...

  16. PCR-DGGE analysis of intestinal bacteria and effect of Bacillus spp. on intestinal microbial diversity in kuruma shrimp ( Marsupenaeus japonicus)

    Science.gov (United States)

    Liu, Huaide; Liu, Mei; Wang, Baojie; Jiang, Keyong; Jiang, Shan); Sun, Shujuan; Wang, Lei

    2010-07-01

    In this study, the intestinal microbiota of kuruma shrimp ( Marsupenaeus japonicus) was examined by molecular analysis of the 16S rDNA to identify the dominant intestinal bacteria and to investigate the effects of Bacillus spp. on intestinal microbial diversity. Samples of the intestines of kuruma shrimp fed normal feed and Bacillus spp. amended feed. PCR and denaturing gradient gel electrophoresis (DGGE) analyses were then performed on DNA extracted directly from the guts. Population fingerprints of the predominant organisms were generated by DGGE analysis of the universal V3 16S rDNA amplicons, and distinct bands in the gels were sequenced. The results suggested that the gut of kuruma shrimp was dominated by Vibrio sp. and uncultured gamma proteobacterium. Overall, the results of this study suggest that PCR-DGGE is a possible method of studying the intestinal microbial diversity of shrimp.

  17. Influence of compost amendments on the diversity of alkane degrading bacteria in hydrocarbon contaminated soils

    Directory of Open Access Journals (Sweden)

    Michael eSchloter

    2014-03-01

    Full Text Available Alkane degrading microorganisms play an important role for bioremediation of petrogenic contaminated environments. In this study, we investigated the effects of compost addition on the diversity of alkane monooxygenase gene (alkB harboring bacteria in oil-contaminated soil originated from an industrial zone in Celje, Slovenia, to improve our understanding about the bacterial community involved in alkane degradation and the effects of amendments. Soil without any amendments (control soil and soil amended with compost of different maturation stages, i 1 year and ii 2 weeks, were incubated under controlled conditions in a microcosm experiment and sampled after 0, 6, 12 and 36 weeks of incubation. By using quantitative real-time PCR higher number of alkB genes could be detected in soil samples with compost compared to the control soil after 6, 12 and 36 weeks mainly if the less maturated compost was added. To get an insight into the composition of the alkB harboring microbial communities, we performed next generation sequencing of alkB gene fragment amplicons. Richness and diversity of alkB gene harboring prokaryotes was higher in soil mixed with compost compared to control soil after 6, 12 and 36 weeks again with stronger effects of the less maturated compost. Comparison of communities detected in different samples and time points based on principle component analysis revealed that the addition of compost in general stimulated the abundance of alkB harboring Actinobacteria during the experiment independent from the maturation stage of the compost compared to the control soils. In addition alkB harboring proteobacteria like Shewanella or Hydrocarboniphaga as well as proteobacteria of the genus Agrobacterium responded positively to the addition of compost to soil The amendment of the less maturated compost resulted in addition in a large increase of alkB harboring bacteria of the Cytophaga group (Microscilla mainly at the early sampling

  18. Microbially influenced corrosion of 303 stainless steel by marine bacterium Vibrio natriegens: (II) Corrosion mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Yin Yansheng, E-mail: yys2006@ouc.edu.cn [Institute of Ocean Materials and Engineering, Shanghai Maritime University, Shanghai 200135 (China); Cheng Sha [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Chen Shougang, E-mail: sgchen@ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Tian Jintao; Liu Tao; Chang Xueting [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China)

    2009-04-30

    Electrochemical techniques (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves) and surface analysis (scanning electron microscopy (SEM)) were carried out to determine the possible mechanism of the microbially influenced corrosion of 303 stainless steel (303 SS) by marine bacterium Vibrio natriegens (V. natriegens). In order to clarify the mechanism, 303 SS coupons were immersed in four different mediums. EIS results were interpreted with different equivalent circuits to model the physicoelectric characteristics of the electrode/biofilm/solution interface. The results showed that N{sub 2}-fixation actually promoted the corrosion of 303 SS; however, the influence of the produced NH{sub 3} was negligible. It can be speculated that the electron transfer and/or the nitrogenase catalyzing the process may influence the corrosion.

  19. Microbial Corrosion of API 5L X-70 Carbon Steel by ATCC 7757 and Consortium of Sulfate-Reducing Bacteria

    Directory of Open Access Journals (Sweden)

    Arman Abdullah

    2014-01-01

    Full Text Available Various cases of accidents involving microbiology influenced corrosion (MIC were reported by the oil and gas industry. Sulfate reducing bacteria (SRB have always been linked to MIC mechanisms as one of the major causes of localized corrosion problems. In this study, SRB colonies were isolated from the soil in suspected areas near the natural gas transmission pipeline in Malaysia. The effects of ATCC 7757 and consortium of isolated SRB upon corrosion on API 5L X-70 carbon steel coupon were investigated using a weight loss method, an open circuit potential method (OCP, and a potentiodynamic polarization curves method in anaerobic conditions. Scanning electron microscopy (SEM and energy dispersive X-ray spectroscopy (EDS were then used to determine the corrosion morphology in verifying the SRB activity and corrosion products formation. Results from the study show that the corrosion rate (CR of weight loss method for the isolated SRB is recorded as 0.2017 mm/yr compared to 0.2530 mm/yr for ATCC 7757. The Tafel plot recorded the corrosion rate of 0.3290 mm/yr for Sg. Ular SRB and 0.2500 mm/yr for Desulfovibrio vulgaris. The results showed that the consortia of isolated SRB were of comparable effects and features with the single ATCC 7757 strain.

  20. Microbial problems and corrosion in oil and oil product storage

    Energy Technology Data Exchange (ETDEWEB)

    Hill, E.C.

    1983-01-01

    This book presents the papers given at a conference on biological fouling and corrosion during the storage of petroleum and petroleum products. Topics considered at the conference included electrochemical aspects of microbial corrosion, the influence of physical and nutritional conditions on microbial growth, hydrocarbon degradation, sulfate-reducing bacteria, corrosion and fouling problems during crude oil and oil product transport, light fuel oils, concrete corrosion, microbial ecology and its significance, and corrosion hazard assessment.

  1. Influence of substrate concentration and feed frequency on ammonia inhibition in microbial fuel cells

    Science.gov (United States)

    Tice, Ryan C.; Kim, Younggy

    2014-12-01

    Excessive amounts of ammonia are known to inhibit exoelectrogenic activities in microbial fuel cells (MFCs). However, the threshold ammonia concentration that triggers toxic effects is not consistent among literature papers, indicating that ammonia inhibition can be affected by other operational factors. Here, we examined the effect of substrate concentration and feed frequency on the capacity of exoelectrogenic bacteria to resist against ammonia inhibition. The high substrate condition (2 g L-1 sodium acetate, 2-day feed) maintained high electricity generation (between 1.1 and 1.9 W m-2) for total ammonia concentration up to 4000 mg-N L-1. The less frequent feed condition (2 g L-1 sodium acetate, 6-day feed) and the low substrate condition (0.67 g L-1 sodium acetate, 2-day feed) resulted in substantial decreases in electricity generation at total ammonia concentration of 2500 and 3000 mg-N L-1, respectively. It was determined that the power density curve serves as a better indicator than continuously monitored electric current for predicting ammonia inhibition in MFCs. The chemical oxygen demand (COD) removal gradually decreased at high ammonia concentration even without ammonia inhibition in electricity generation. The experimental results demonstrated that high substrate concentration and frequent feed substantially enhance the capacity of exoelectrogenic bacteria to resist against ammonia inhibition.

  2. Non-destructive on-line monitoring of MIC (microbially influenced corrosion)

    Energy Technology Data Exchange (ETDEWEB)

    White, D.C. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA)); Nivens, D.E.; Mittelman, M.W. (Tennessee Univ., Knoxville, TN (USA). Inst. for Applied Microbiology); Chambers, J.Q. (Tennessee Univ., Knoxville, TN (USA). Dept. of Chemistry); King, J.M.H. (Tennessee Univ., Knoxville, TN (USA). Center for Environmental Biotechnology); Sayler, G.S. (Tennessee Univ., Knoxville, TN

    1990-01-01

    The formation of microbial biofilms on metal surfaces with the subsequent increase in heat transfer resistance and the induction of microbially influenced corrosion (MIC) is being increasingly recognized as an extremely important economic and safety problem for industrial water systems. The development of sufficiently rugged and accurate monitoring devices by which biofilm formation and activity of microbial biofilms can be monitored non-destructively, directly in water systems is the goal of this research. This on-line systems would allow the effective utilization of minimal levels of biocides and inhibitors as well as permit in situ testing of materials for MIC resistance. Several non-destructive technologies such as the quartz crystal microbalance (QCM), the attenuated total reflectance-Fourier transforming infrared spectrometer (ATR-FT/IR), and a genetically engineered bacterium containing the lux gene cassette in which its bioluminescence can be used to define its presence on coupons are on-line devices which accurately measure biofilm formation. Corrosion activity can be estimated by electrochemical impedance. 12 refs., 8 figs.

  3. Cathodic protection criteria for controlling microbially influenced corrosion in power plants

    Energy Technology Data Exchange (ETDEWEB)

    Nekoksa, G. (Corrosion Failure Analysis and Control, San Ramon, CA (USA)); Gutherman, B. (Florida Power Corp., St. Petersburg, FL (USA))

    1991-05-01

    The main objective of this project was to evaluate galvanic corrosion on coupled samples and to determine cathodic protection criteria and effectiveness on four materials in an untreated seawater cooling system with microbially influenced corrosion. Hydrogen embrittlement of two cathodically protected high performance condenser tube materials was also evaluated. The long-term field testing was conducted at the intake structure of Florida Power Corporation's Crystal River Unit 3 Nuclear Power Plant. The test results indicate that Type 304L stainless steel can be galvanically corroded when coupled to Cu/Ni and fully cathodically protected when coupled to a carbon steel anode. Cathodic protection did protect carbon steel, but less than expected from the literature. The cathodic protection effectiveness on carbon steel was approximately 82% at {minus}1.01 V (SCE). To prevent hydrogen embrittlement, the tested titanium or ferritic stainless steel should not be polarized to more negative potentials than {minus}0.75 V (SCE). This report consists of a literature search, preliminary laboratory polarization testing, laboratory testing to determine microbial effects caused by an interruption of cathodic current, development of exposure racks for long-term electrochemical testing and analyses of corrosion, metallurgical, microbial and chemical data. 44 refs., 26 figs., 9 tabs.

  4. In-Stream Activities Influence Microbial Water Quality of a Shallow Mountain Stream in Rural Kenya.

    OpenAIRE

    Yillia, P.T.; Kreuzinger, N; Mathooko, J.M.

    2000-01-01

    The influence of periodic in-stream activities of people and livestock on the microbial water quality of the Njoro River in Kenya was monitored at two disturbed pools (Turkana Flats and Njoro Bridge) at the middle reaches. A total of ninety-six sets of samples were obtained from the two pools. On each sampling day, two trips were made before and during in-stream activities and on each trip, two sets of samples were collected upstream and downstream of activities. This schedule was repeated fo...

  5. Characterization of the microbial community in a lotic environment to assess the effect of pollution on nitrifying and potentially pathogenic bacteria.

    Science.gov (United States)

    Medeiros, J D; Araújo, L X; da Silva, V L; Diniz, C G; Cesar, D E; Del'Duca, A; Coelho, C M

    2014-08-01

    This study aimed to investigate microbes involved in the nitrogen cycle and potentially pathogenic bacteria from urban and rural sites of the São Pedro stream. Water samples were collected from two sites. A seasonal survey of bacterial abundance was conducted. The dissolved nutrient content was analysed. PCR and FISH analysis were performed to identify and quantify microbes involved in the nitrogen cycle and potentially pathogenic bacteria. The seasonal survey revealed that the bacterial abundance was similar along the year on the rural area but varied on the urban site. Higher concentration of dissolved nutrients in the urban area indicated a eutrophic system. Considering the nitrifying microbes, the genus Nitrobacter was found, especially in the urban area, and may act as the principal bacteria in converting nitrite into nitrate at this site. The molecular markers napA, amoA, and nfrA were more accumulated at the urban site, justifying the higher content of nutrients metabolised by these enzymes. Finally, high intensity of amplicons from Enterococcus, Streptococcus, Bacteroides/Prevotella/Porphyromonas, Salmonella, S. aureus, P. aeruginosa and the diarrheagenic lineages of E. coli were observed at the urban site. These results indicate a change in the structure of the microbial community imposed by anthrophic actions. The incidence of pathogenic bacteria in aquatic environments is of particular importance to public health, emphasising the need for sewage treatment to minimise the environmental impacts associated with urbanisation. PMID:25296210

  6. Influence of temperature on phenanthrene toxicity towards nitrifying bacteria in three soils with different properties.

    Science.gov (United States)

    Suszek-Łopatka, Beata; Maliszewska-Kordybach, Barbara; Klimkowicz-Pawlas, Agnieszka; Smreczak, Bożena

    2016-09-01

    This study focused on the combined effect of environmental conditions (temperature) and contamination (polycyclic aromatic hydrocarbons, PAHs) on the activity of soil microorganisms (nitrifying bacteria). Phenanthrene (Phe) at five contamination levels (0, 1, 10, 100 and 1000 mg kg(-1) dry mass of soil) was employed as a model PAH compound in laboratory experiments that were conducted at three temperatures (i.e., 20 °C (recommended by ISO 15685 method), 15 and 30 °C). Three soils with different properties were used in these studies, and the activity of the nitrifying bacteria was assessed based on nitrification potential (NP) determinations. For the statistical evaluation of the results, the ANCOVA (analysis of covariance) method for three independent variables (i.e., temperature, phenanthrene concentration, soil matrix (as a qualitative variable)) and their interactions was employed. The results indicated on the significant interaction of all studied factors. Temperature influenced the toxicity of Phe towards NP, and this effect was related to the Phe concentration as well as was varied for the different soils. A low content of soil organic matter (controlling bioavailability of phenanthrene to soil microorganisms) enhanced the combined effect of temperature and Phe toxicity, and a high biological activity of the soil (high NP values) increased the effect of high temperature on the Phe stimulatory influence. The results indicate that the temperature should not be neglected in tests evaluating PAH ecotoxicity, especially for reliable ecological risk assessment. PMID:27394082

  7. Landscape position influences microbial composition and function via redistribution of soil water across a watershed.

    Science.gov (United States)

    Du, Zhe; Riveros-Iregui, Diego A; Jones, Ryan T; McDermott, Timothy R; Dore, John E; McGlynn, Brian L; Emanuel, Ryan E; Li, Xu

    2015-12-01

    Subalpine forest ecosystems influence global carbon cycling. However, little is known about the compositions of their soil microbial communities and how these may vary with soil environmental conditions. The goal of this study was to characterize the soil microbial communities in a subalpine forest watershed in central Montana (Stringer Creek Watershed within the Tenderfoot Creek Experimental Forest) and to investigate their relationships with environmental conditions and soil carbonaceous gases. As assessed by tagged Illumina sequencing of the 16S rRNA gene, community composition and structure differed significantly among three landscape positions: high upland zones (HUZ), low upland zones (LUZ), and riparian zones (RZ). Soil depth effects on phylogenetic diversity and β-diversity varied across landscape positions, being more evident in RZ than in HUZ. Mantel tests revealed significant correlations between microbial community assembly patterns and the soil environmental factors tested (water content, temperature, oxygen, and pH) and soil carbonaceous gases (carbon dioxide concentration and efflux and methane concentration). With one exception, methanogens were detected only in RZ soils. In contrast, methanotrophs were detected in all three landscape positions. Type I methanotrophs dominated RZ soils, while type II methanotrophs dominated LUZ and HUZ soils. The relative abundances of methanotroph populations correlated positively with soil water content (R = 0.72, P < 0.001) and negatively with soil oxygen (R = -0.53, P = 0.008). Our results suggest the coherence of soil microbial communities within and differences in communities between landscape positions in a subalpine forested watershed that reflect historical and contemporary environmental conditions. PMID:26431971

  8. Influence of Chicken Manure Fertilization on Antibiotic-Resistant Bacteria in Soil and the Endophytic Bacteria of Pakchoi.

    Science.gov (United States)

    Yang, Qingxiang; Zhang, Hao; Guo, Yuhui; Tian, Tiantian

    2016-01-01

    Animal manure is commonly used as fertilizer for agricultural crops worldwide, even though it is believed to contribute to the spread of antibiotic resistance from animal intestines to the soil environment. However, it is unclear whether and how there is any impact of manure fertilization on populations and community structure of antibiotic-resistant endophytic bacteria (AREB) in plant tissues. To investigate the effect of manure and organic fertilizer on endophytic bacterial communities, pot experiments were performed with pakchoi grown with the following treatments: (1) non-treated; (2) chicken manure-treated and (3) organic fertilizer-treated. Manure or organic fertilizer significantly increased the abundances of total cultivable endophytic bacteria (TCEB) and AREB in pakchoi, and the effect of chicken manure was greater than that of organic fertilizer. Further, 16S rDNA sequencing and the phylogenetic analysis indicated that chicken manure or organic fertilizer application increased the populations of multiple antibiotic-resistant bacteria (MARB) in soil and multiple antibiotic-resistant endophytic bacteria (MAREB) in pakchoi. The identical multiple antibiotic-resistant bacterial populations detected in chicken manure, manure- or organic fertilizer-amended soil and the vegetable endophytic system were Brevundimonas diminuta, Brachybacterium sp. and Bordetella sp., suggesting that MARB from manure could enter and colonize the vegetable tissues through manure fertilization. The fact that some human pathogens with multiple antibiotic resistance were detected in harvested vegetables after growing in manure-amended soil demonstrated a potential threat to human health. PMID:27376311

  9. Influence of Chicken Manure Fertilization on Antibiotic-Resistant Bacteria in Soil and the Endophytic Bacteria of Pakchoi.

    Science.gov (United States)

    Yang, Qingxiang; Zhang, Hao; Guo, Yuhui; Tian, Tiantian

    2016-01-01

    Animal manure is commonly used as fertilizer for agricultural crops worldwide, even though it is believed to contribute to the spread of antibiotic resistance from animal intestines to the soil environment. However, it is unclear whether and how there is any impact of manure fertilization on populations and community structure of antibiotic-resistant endophytic bacteria (AREB) in plant tissues. To investigate the effect of manure and organic fertilizer on endophytic bacterial communities, pot experiments were performed with pakchoi grown with the following treatments: (1) non-treated; (2) chicken manure-treated and (3) organic fertilizer-treated. Manure or organic fertilizer significantly increased the abundances of total cultivable endophytic bacteria (TCEB) and AREB in pakchoi, and the effect of chicken manure was greater than that of organic fertilizer. Further, 16S rDNA sequencing and the phylogenetic analysis indicated that chicken manure or organic fertilizer application increased the populations of multiple antibiotic-resistant bacteria (MARB) in soil and multiple antibiotic-resistant endophytic bacteria (MAREB) in pakchoi. The identical multiple antibiotic-resistant bacterial populations detected in chicken manure, manure- or organic fertilizer-amended soil and the vegetable endophytic system were Brevundimonas diminuta, Brachybacterium sp. and Bordetella sp., suggesting that MARB from manure could enter and colonize the vegetable tissues through manure fertilization. The fact that some human pathogens with multiple antibiotic resistance were detected in harvested vegetables after growing in manure-amended soil demonstrated a potential threat to human health.

  10. Adaptation of Bacteria of Anaerobic Digestion to Higher Salinity for the Application to Microbial Enhanced Oil Recovery

    DEFF Research Database (Denmark)

    Rudyk, Svetlana Nikolayevna; Ivanova, Yanina; Spirov, Pavel;

    For this study, bacteria of anaerobic digestion from Ribe Biogas plant, Denmark, were chosen. The volume of the produced gas from the bacteria was measured in a water displacement setup every day. After the gas production ceased in the second day, the maximum produced gas was measured at 70 and 90...

  11. Concurrent Phosphorus Recovery and Energy Generation in Mediator-Less Dual Chamber Microbial Fuel Cells: Mechanisms and Influencing Factors

    OpenAIRE

    Abdullah Almatouq; Akintunde O. Babatunde

    2016-01-01

    This study investigated the mechanism and key factors influencing concurrent phosphorus (P) recovery and energy generation in microbial fuel cells (MFC) during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite when ammonium and magnesium chloride solutions were added to the cathode chamber. Monitoring data for chemical oxygen demand (COD), pH, oxidation reduction potential (ORP) and aeration flow rate sho...

  12. Influence of carbon steel grade on the initial attachment of bacteria and microbiologically influenced corrosion.

    Science.gov (United States)

    Javed, M A; Neil, W C; Stoddart, P R; Wade, S A

    2016-01-01

    The influence of the composition and microstructure of different carbon steel grades on the initial attachment (≤ 60 min) of Escherichia coli and subsequent longer term (28 days) corrosion was investigated. The initial bacterial attachment increased with time on all grades of carbon steel. However, the rate and magnitude of bacterial attachment varied on the different steel grades and was significantly less on the steels with a higher pearlite phase content. The observed variations in the number of bacterial cells attached across different steel grades were significantly reduced by applying a fixed potential to the steel samples. Longer term immersion studies showed similar levels of biofilm formation on the surface of the different grades of carbon steel. The measured corrosion rates were significantly higher in biotic conditions compared to abiotic conditions and were found to be positively correlated with the pearlite phase content of the different grades of carbon steel coupons. PMID:26785935

  13. THE AGGREGATION OF BACTERIA KLEBSIELLA OXYTOCA AND KLEBSIELLA PNEUMONIAE UNDER THE INFLUENCE OF CHEMICAL FACTOR

    Directory of Open Access Journals (Sweden)

    G. R. Sadrtdinova

    2015-01-01

    Full Text Available The article acknowledges the formation of bacterial biofilms in strains of bacteria species Klebsiella oxytoca and Klebsiella pneumoniae when grown in liquid media under the influence of negative factors (chemical factor — containing agents. Biofilms, as a community of microorganisms cause many chronic infections (meningitis, inflammatory diseases of the oral cavity, urogenital infections and create problems in the industry (fouling of processing equipment, ship hulls, oil platforms, biocorrosion metal products. Ordinary disinfectants, such as chlorine and sodium chlorite, can not remove the biofilm, so finding an effective means of dealing with them is enough actual problem. Various antibacterial agents are ineffective in combating biofilms, since bacteria produce large amounts of polysaccharides — substances that help the colony stay without disintegration. Polysaccharide serves as a barrier layer for substances in water, including for biocides. This is the main reason for the survival of microorganisms even in the heavily chlorinated water. In the study the latest data took into account on the subject, especially concerning adverse effects of oxygen on the growth of bacterial cells and directs action as a factor in the formation of biofilms. In our study we analyzed the latest generation disinfectant as an influencing factor. Working concentrations were shown in three embodiments. The number of strains studied was 6 (3 strains of each species. All strains were obtained from the Department of Museum MVE and VSE Ulyanovsk State Agricultural Academy n.a. P.A. Stolypin. In our research the biofilm community formation phenomenon has been confirmed, marked differences in biofilm formation, depending on the intensity (in this case, concentration of the promoter and bacteria species. In vivo biofilm is easily destroyed by mechanical action (shaking test tubes with the medium. Biofilm recovery after this manipulation was not observed. The results

  14. Giardia duodenalis-induced alterations of commensal bacteria kill Caenorhabditis elegans: a new model to study microbial-microbial interactions in the gut.

    Science.gov (United States)

    Gerbaba, Teklu K; Gupta, Pratyush; Rioux, Kevin; Hansen, Dave; Buret, Andre G

    2015-03-15

    Giardia duodenalis is the most common cause of parasitic diarrhea worldwide and a well-established risk factor for postinfectious irritable bowel syndrome. We hypothesized that Giardia-induced disruptions in host-microbiota interactions may play a role in the pathogenesis of giardiasis and in postgiardiasis disease. Functional changes induced by Giardia in commensal bacteria and the resulting effects on Caenorhabditis elegans were determined. Although Giardia or bacteria alone did not affect worm viability, combining commensal Escherichia coli bacteria with Giardia became lethal to C. elegans. Giardia also induced killing of C. elegans with attenuated Citrobacter rodentium espF and map mutant strains, human microbiota from a healthy donor, and microbiota from inflamed colonic sites of ulcerative colitis patient. In contrast, combinations of Giardia with microbiota from noninflamed sites of the same patient allowed for worm survival. The synergistic lethal effects of Giardia and E. coli required the presence of live bacteria and were associated with the facilitation of bacterial colonization in the C. elegans intestine. Exposure to C. elegans and/or Giardia altered the expression of 172 genes in E. coli. The genes affected by Giardia included hydrogen sulfide biosynthesis (HSB) genes, and deletion of a positive regulator of HSB genes, cysB, was sufficient to kill C. elegans even in the absence of Giardia. Our findings indicate that Giardia induces functional changes in commensal bacteria, possibly making them opportunistic pathogens, and alters host-microbe homeostatic interactions. This report describes the use of a novel in vivo model to assess the toxicity of human microbiota. PMID:25573177

  15. Effects of water quality on the influence of cadmium to microbial enzyme activity

    Energy Technology Data Exchange (ETDEWEB)

    McKarus, J.N.; Scheuerman, P.R.; Lanza, G.R.; Eckels, M.A. [East Tennessee State Univ., Johnson City, TN (United States). Dept. of Environmental Health

    1994-12-31

    Studies in the laboratory have demonstrated that water quality changes affect the toxicity of Cd{sup +2} to aquatic organisms. This study examined the potential of selected microbial enzyme activities (MEA`s) to show the same effects. Enzymes measured were dehydrogenase (DHA), alkaline phosphatase (ALK), glucosidase (GLU), and galactosidase (GAL). The influence of water quality changes on Cd{sup +2} toxicity to bacterial populations was also examined. A significant difference in ALK and GLU was observed under control conditions in unimpacted and impacted creek water. Cadmium had a significant effect on microbial activity in impacted creek water at 8.75, 4.0, and 0.8 mg Cd{sup +2}/L. Effects observed were not consistent for all Cd{sup +2} concentrations. Significant differences were observed with DHA at Cd{sup +2} concentrations of 4.0 mg Cd{sup +2}/L. Water quality influenced the effect of Cd{sup +2} on enzyme activity at 0.8 and 8.75 mg Cd{sup +2}/L with a high carbonate hardness, and 4.0 mg Cd{sup +2}/L with a high non-carbonate hardness. Variability in water quality may have resulted from seasonal affects. Results indicate that levels of hardness and alkalinity along with seasonal change are crucial elements when establishing site-specific water quality and biomonitoring criteria.

  16. Influent wastewater microbiota and temperature influence anaerobic membrane bioreactor microbial community.

    Science.gov (United States)

    Seib, M D; Berg, K J; Zitomer, D H

    2016-09-01

    Sustainable municipal wastewater recovery scenarios highlight benefits of anaerobic membrane bioreactors (AnMBRs). However, influences of continuous seeding by influent wastewater and temperature on attached-growth AnMBRs are not well understood. In this study, four bench-scale AnMBR operated at 10 and 25°C were fed synthetic (SPE) and then real (PE) primary effluent municipal wastewater. Illumina sequencing revealed different bacterial communities in each AnMBR in response to temperature and bioreactor configuration, whereas differences were not observed in archaeal communities. Activity assays revealed hydrogenotrophic methanogenesis was the dominant methanogenic pathway at 10°C. The significant relative abundance of Methanosaeta at 10°C concomitant with low acetoclastic methanogenic activity may indicate possible Methanosaeta-Geobacter direct interspecies electron transfer. When AnMBR feed was changed to PE, continual seeding with wastewater microbiota caused AnMBR microbial communities to shift, becoming more similar to PE microbiota. Therefore, influent wastewater microbiota, temperature and reactor configuration influenced the AnMBR microbial community. PMID:27262719

  17. IN VITRO CHARACTERIZATION OF PROBIOTIC PROPERTIES OF LACTIC ACID BACTERIA FROM BULGARIAN RYE SOURDOUGHS

    OpenAIRE

    Dobreva-Yosifova, G.; Yocheva, L.; Mehmed, A.; Danova, S.; Antonova-Nikolova, S.

    2009-01-01

    Lactic acid bacteria play a key role in human health. These friendly bacteria as a part of the microflora of the gastrointestinal tract (GIT) have a beneficial influence on microbial balance. The probiotic cultures stimulate the growth of beneficial microorganisms, crowd out potentially harmful bacteria and reinforce the body's natural defense mechanisms. Recent data improve the positive effects of probiotics and stimulate research for discovering of new lactic acid bacteria strains with prob...

  18. An investigation of microbial diversity in crude oil & seawater injection systems and microbiologically influenced corrosion (MIC) of linepipe steels under different exposure conditions

    Science.gov (United States)

    AlAbbas, Faisal Mohammed

    During oil and gas operations, pipeline networks are subjected to different corrosion deterioration mechanisms that result from the interaction between the fluid process and the linepipe steel. Among these mechanisms is microbiologically influenced corrosion (MIC) that results from accelerated deterioration caused by different indigenous microorganisms that naturally reside in the hydrocarbon and associated seawater injection systems. The focus of this research is to obtain comprehensive understanding of MIC. This work has explored the most essential elements (identifications, implications and mitigations) required to fully understand MIC. Advanced molecular-based techniques, including sequencing of 16S rRNA genes via 454 pyrosequencing methodologies, were deployed to provide in-depth understanding of the microbial diversity associated with crude oil and seawater injection systems and their relevant impact on MIC. Key microbes including sulfate reducing bacteria (SRB) and iron reducing bacteria (IRB) were cultivated from sour oil well field samples. The microbes' phylotypes were identified in the laboratory to gain more thorough understanding of how they impact microbial corrosion. Electrochemical and advanced surface analytical techniques were used for corrosion evaluations of linepipe carbon steels (API 5L X52 and X80) under different exposure conditions. On the identification front, 454 pyrosequencing of both 16S rRNA genes indicated that the microbial communities in the corrosion products obtained from the sour oil pipeline, sweet crude pipeline and seawater pipeline were dominated by bacteria, though archaeal sequences (predominately Methanobacteriaceae and Methanomicrobiaceae) were also identified in the sweet and sour crude oil samples, respectively. The dominant bacterial phylotypes in the sour crude sample included members of the Thermoanaerobacterales, Synergistales, and Syntrophobacterales. In the sweet crude sample, the dominant phylotypes included

  19. [Influence of substrate COD on methane production in single-chambered microbial electrolysis cell].

    Science.gov (United States)

    Teng, Wen-Kai; Liu, Guang-Li; Luo, Hai-Ping; Zhang, Ren-Duo; Fu, Shi-Yu

    2015-03-01

    The chemical oxygen demand (COD) of substrate can affect the microbial activity of both anode and cathode biofilm in the single-chamber methanogenic microbial electrolysis cell (MEC). In order to investigate the effect of COD on the performance of MEC, a single chamber MEC was constructed with biocathode. With the change of initial concentration of COD (700, 1 000 and 1 350 mg x L(-1)), the methane production rate, COD removal and energy efficiency in the MEC were examined under different applied voltages. The results showed that the methane production rate and COD removal increased with the increasing COD. With the applied voltage changing from 0.3 to 0.7 V, the methane production rate increased at the COD of 700 mg x L(-1), while it increased at first and then decreased at the COD of 1000 mg x L(-1) and 1350 mg x L(-1). A similar trend was observed for the COD removal. The cathode potential reached the minimum (- 0.694 ± 0.001) V as the applied voltage was 0.5 V, which therefore facilitated the growth of methanogenic bacteria and improved the methane production rate and energy efficiency of the MEC. The maximum energy income was 0.44 kJ ± 0.09 kJ (1450 kJ x m(-3)) in the MEC, which was obtained at the initial COD of 1000 mg x L(-1) and the applied voltage of 0.5 V. Methanogenic MECs could be used for the treatment of wastewaters containing low organic concentrations to achieve positive energy production, which might provide a new method to recover energy from low-strength domestic wastewater.

  20. The influences of fish infusion broth on the biogenic amines formation by lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Esmeray Küley

    2013-01-01

    Full Text Available The influences of fish infusion decarboxylase broth (IDB on biogenic amines (BA formation by lactic acid bacteria (LAB were investigated. BA productions by single LAB strains were tested in five different fish (anchovy, mackerel, white shark, sardine and gilthead seabream IDB. The result of the study showed that significant differences in ammonia (AMN and BA production were observed among the LAB strains in fish IDB (p < 0.05. The highest AMN and TMA production by LAB strains were observed for white shark IDB. The all tested bacteria had decarboxylation activity in fish IDB. The uppermost accumulated amines by LAB strains were tyramine (TYM, dopamine, serotonin and spermidine. The maximum histamine production was observed in sardine (101.69 mg/L and mackerel (100.84 mg/L IDB by Leuconostoc mesenteroides subsp. cremoris and Pediococcus acidophilus, respectively. Lactobacillus delbrueckii subsp. lactis and Pediococcus acidophilus had a high TYM producing capability (2943 mg/L and 1157 mg/L in sardine IDB.

  1. Effects of Neutral Detergent Soluble Fiber and Sucrose Supplementation on Ruminal Fermentation, Microbial Synthesis, and Populations of Ruminal Cellulolytic Bacteria Using the Rumen Simulation Technique (RUSITEC)

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiang-hui; LIU Chan-juan; LI Chao-yun; YAO Jun-hu

    2013-01-01

    We evaluated the effects of neutral detergent soluble fiber (NDSF) and sucrose supplementation on ruminal fermentation, microbial synthesis, and populations of ruminal cellulolytic bacteria using the rumen simulation technique (RUSITEC). The experiment had a 2×2 factorial design with two dosages of sucrose, low (ca. 0.26 g d-1, low-sucrose) and high (ca. 1.01 g d-1, high-sucrose), and two dosages of supplied NDSF, low (1.95 g d-1, low-NDSF) and high (2.70 g d-1, high-NDSF). Interactions between NDSF and sucrose were detected for xylanase activity from solid fraction and apparent disappearance of neutral detergent fiber (NDF) and hemicellulose, with the lowest values observed for high-NDSF and high-sucrose treatment. Supplemental NDSF appeared to increase the molar proportion of acetate and reduce that of butyrate;however, the effects of supplemental sucrose on VFA profiles depended upon NDSF amount. There was a NDSF×sucrose interaction for the production of methane. High-NDSF fermenters had lower ammonia-N production, greater daily N flow of solid-associated microbial pellets and total microorganisms, and greater microbial synthesis efficiency compared with low-NDSF fermenters. Supplementation with NDSF resulted in an increase in 16S rDNA copies of Ruminococcus flavefaciens and a reduction in copies of Ruminococcus albus. Supplementation with sucrose tended to increase the 16S rDNA copies of R. albus from liquid fraction, but did not affect daily total microbial N flow and cellulolytic bacterium populations from solid fraction. These data indicate that the effects of the interaction between NDSF and sugars on ruminal fermentation and fiber digestion should be taken into account in diet formulation. Ruminal fermentation and metabolism of sugars warrant further investigation.

  2. Epilobi Hirsuti Herba Extracts Influence the In Vitro Activity of Common Antibiotics on Standard Bacteria

    Directory of Open Access Journals (Sweden)

    Pirvu Lucia

    2016-03-01

    Full Text Available Epilobium genus has been confirmed as an effective source of natural antimicrobials. However, the influence of Epilobi hirsuti herba derived products on usual antibiotics activity has not been studied. In this study, several standardized Epilobi hirsuti herba extracts (EHE were evaluated in order to asses their potential effects on usual antibiotics tested on standard Gram-positive and Gram-negative bacterial strains in vitro. The results emphasized that the bacterial strains ranged from sensitive (MIC values between 50–200 μg GAE mL-1 (S. epidermidis ATCC 12228 to very resistant (E. coli strains, E. faecalis ATCC 29212 being practically immune to EHE. In terms of synergistic interaction, Tetracycline and Ampicillin combinations lead to the most important stimulatory effects, the diameters of the inhibition zone being even 60% bigger compared to the antibiotic alone. Synergistic effects between myricetin(galloyl derivates and Tetracycline were also revealed on P. aeruginosa and E. coli strains. Together, it clearly demonstrated not only EHE’s own antimicrobial properties, but also their capacity to influence the antimicrobial potency of some common antibiotics. These results could be useful for the area of herbal medicines and as potential candidates in managing microbial resistance, but also for physicians and pharmacists using combined antibacterial therapy.

  3. The influence of the different initial probiotic bacteria concentration on sweet whey fermentation

    Directory of Open Access Journals (Sweden)

    Bojan Matijević

    2008-12-01

    Full Text Available Whey is nutritiously very high-quality secondary product from cheese making which is not used enough in human diet. When the fermentation is performed with probiotic bacteria it additionally increases its nutritional and health values. This research examines the influence of different amount of inoculum addition (2.5, 5 and 7.5 % of monoculture Lactobacillus acidophilus La-5 or Bifidobacterium animalis subsp. lactis BB-12, on the course of fermentation of reconstitued sweet whey at 37 °C. During fermentation and 28 days of cool storage fermented whey pH value, titratable acidity and the viable cells count was monitored. Fermentation with 7.5 % inoculum of monoculture Lactobacillus acidophilus La-5 lasted the shortest (about 13.3 hours, while the fermentation with 2.5 % inoculum lasted the longest (about 15.5 hours. The viable cells count of Lactobacillus acidophilus La-5 cells in all whey samples has increased during fermentation for about 1.3 log CFU/mL and at the end of fermentation was about 8.5 log CFU/mL. Whey fermentation with 7.5 % added inoculum of monoculture Bifidobacterium animalis subsp. lactis BB-12 showed no difference in duration time in comparison to whey fermentation with 2.5 % inoculum addition. The viable cells count of Bifidobacterium animalis subsp. lactis BB-12 has increased during fermentation for about 0.9 log CFU/mL and at the end of fermentation was about 8.7 log CFU/mL. The amount of inoculum had no influence on survival of probiotic bacteria in fermented whey regardless of monoculture used.

  4. Influence of hexavalent chromium on lactate-enriched Hanford groundwater microbial communities.

    Energy Technology Data Exchange (ETDEWEB)

    Somenahally, Anil C [ORNL; Mosher, Jennifer J [ORNL; Yuan, Tong [University of Oklahoma; Podar, Mircea [ORNL; Phelps, Tommy Joe [ORNL; Brown, Steven D [ORNL; Yang, Zamin Koo [ORNL; Hazen, Terry C [ORNL; Arkin, Adam [Lawrence Berkeley National Laboratory (LBNL); Palumbo, Anthony Vito [ORNL; Zhou, Jizhong [University of Oklahoma; Elias, Dwayne A [ORNL

    2013-01-01

    Microbial reduction and immobilization of chromate (Cr(VI)) is a plausible bioremediation strategy. However, higher Cr(VI) concentrations may impose stress on native Cr-reducing communities. We sought to determine if Cr(VI) would influence the lactate enriched native microbial community structure and function in groundwater from the Cr contaminated site at Hanford, WA. Steady state continuous flow bioreactors were amended with lactate and Cr(VI) (0.0, 0.1 and 3.0 mg/L). Microbial growth, metabolites, Cr(VI) concentrations, 16S rRNA gene sequences and GeoChip based functional gene composition in bioreactors were monitored for 15 weeks. Temporal trends and some differences in growth, metabolite profiles, and community composition were observed, largely between Low-Cr and High-Cr bioreactors. In both High-Cr and Low-Cr bioreactors, Cr(VI) was reduced in the bioreactors. With lactate enrichment, the native communities did not significantly differ between Cr concentrations. Native bacterial communities were diverse, whereas after lactate enrichment, Pelosinus spp., and Sporotalea spp., were the most predominant groups in all bioreactors. Similarly, the Archaea diversity significantly decreased from Methanosaeta (35%), Methanosarcina (17%), Halobacteriales (12%), Methanoregula (8%) and others, to mostly Methanosarcina spp. (95%) after lactate enrichment. Composition of several key functional genes was distinct in Low-Cr bioreactors compared to High-Cr. Among the Cr resistant probes (chrA), Burkholderia vietnamiensis, Comamonas testosterone and Ralstonia pickettii proliferated in Cr amended bioreactors. In-situ fermentative conditions facilitated Cr(VI) reduction, and as a result the 3.0 mg/L Cr(VI) did not appear to give chromate reducing strains a competitive advantage for proliferation or for increasing Cr-reduction.

  5. Co-composting of biowaste and wood ash, influence on a microbially driven-process.

    Science.gov (United States)

    Fernández-Delgado Juárez, Marina; Prähauser, Barbara; Walter, Andreas; Insam, Heribert; Franke-Whittle, Ingrid H

    2015-12-01

    A trial at semi-industrial scale was conducted to evaluate the effect of wood ash amendment on communal biowaste in a composting process and on the final composts produced. For this purpose, three treatments including an unamended control (C0) and composts with additions of 6% (C6), and 12% (C12) of wood ash (w/w) were studied, and physico-chemical parameters as well as microbial activity and community composition were investigated. At the end of the process, composts were tested for toxicity and quality, and microbial physiological activity. The influence of ash addition on compost temperature, pH, microbial activity and composition was stronger during the early composting stages and diminished with time, whereby composts became more similar. Using the COMPOCHIP microarray, a reduction in the pathogenic genera Listeria and Clostridium was observed, which together with the temperature increases of the composting process helped in the hygienisation of composts. Lactobacillus species were also affected, such that reduced hybridisation signals were observed with increased ash addition, due to the increased pH values in amended composts. Organic matter mineralisation was also increased through ash addition, and no negative effects on the composting process were observed. The nutrient content of the final products was increased through the addition of ash, and no toxic effects were observed. Nonetheless, greater concentrations of heavy metals were found in composts amended with more ash, which resulted in a downgrading of the compost quality according to the Austrian Compost Ordinance. Thus, regulation of both input materials and end-product quality is essential in optimising composting processes. PMID:26394680

  6. QCM study of microbially influenced corrosion of aluminium subjected to the influence of Aspergillus niger Tiegh

    OpenAIRE

    Miečinskas, Povilas; Leinartas, Konstantinas; Uksienė, Virginija; Lugauskas, Albinas; Ramanauskas, Rimantas; Juzeliūnas, Eimutis

    2006-01-01

    Aspergillus niger Tiegh., a filamentous ascomycete fungus, was isolated from metal samples exposed to marine, rural and urban sites in Lithuania. Al samples prepared as glued foil electrodes on quartz crystal microbalance were subjected to a long-term influence (three months) of A. niger under laboratory conditions in humid atmosphere. The comparison of the QCM data between the samples affected by A. niger and abiotic ones showed a marked increase in the electrode mass due to the development ...

  7. Microbial degradation of chlorinated compounds. Application of specialized bacteria in the treatment of contaminated soil and waste water.

    NARCIS (Netherlands)

    Oldenhuis, Roelof

    1992-01-01

    The development of (aerobic) treatment technologies for polluted environments and waste streams will require an understanding of the microbial potential and the ecophysiology of the most suitable organisms. Therefore, we have studied physiological pathways and some kinetic aspects of the biotransfor

  8. Screening of lactic acid bacteria for their potential as microbial cell factories for bioconversion of lignocellulosic feedstocks

    DEFF Research Database (Denmark)

    Boguta, Anna Monika; Bringel, Francoise; Martinussen, Jan;

    2014-01-01

    biomass into desirable value added products. However, such bioprocesses require availability of suitable and efficient microbial biocatalysts, capable of utilizing C5 sugars and tolerant to inhibitory compounds generated during pretreatment of biomass. In this study, the performance of a collection...

  9. [Influences of water-saved and nitrogen-reduced practice on soil microbial and microfauna assemblage in paddy field].

    Science.gov (United States)

    Gui, Juan; Chen, Xiao-yun; Liu, Man-qiang; Zhuang, Xi-ping; Sun, Zhen; Hu, Feng

    2016-01-01

    The resource and environmental problems caused by excessive consumption of water and fertilizer in rice production have recently aroused widespread concern. This study investigated the effects of irrigation modes (conventional irrigation and 25% water-saved irrigation) and different N application rates (conventional high-nitrogen fertilization and 40% nitrogen-reduced fertilization) on microbial and microfauna assemblages at tillering and ripening stages in paddy field. The results showed that compared with conventional irrigation (CF), water-saved irrigation (WS) decreased the soil pH at tillering stage. Soil dissolved organic matter (dissolved organic C and N) and microbial biomass C and N were significantly affected by irrigation, nitrogen fertilizer and their interactions. WS or N-reduced fertilization (LN) decreased the contents of dissolved organic matter; WS increased microbial biomass C but decreased microbial biomass N. Nitrate was significantly higher in WS than CF, while ammonium showed reverse pattern. At tillering stage, the soil microbial biomass from bacteria, fungi, actinomy and protozoa was higher in WS than in CF, but the trend was opposite at ripening stage. There was a significant interation between irrigation and fertilization on soil rotifer numbers and microbial-feeding nematodes. At tillering stage, WS increased the numbers of rotifer and nematode, and also the proportion of bacterial-feeding nematode; LN increased the abundance of rotifer but decreased the abundance of nematode. In summary, soil microbial and microfauna assemblages showed different response to water-saved and nitrogen-reduced agricultural managements, which depended on different crop growth stages, but also the complex interactions of water and nitrogen and between biological groups in food webs. PMID:27228599

  10. [Influences of water-saved and nitrogen-reduced practice on soil microbial and microfauna assemblage in paddy field].

    Science.gov (United States)

    Gui, Juan; Chen, Xiao-yun; Liu, Man-qiang; Zhuang, Xi-ping; Sun, Zhen; Hu, Feng

    2016-01-01

    The resource and environmental problems caused by excessive consumption of water and fertilizer in rice production have recently aroused widespread concern. This study investigated the effects of irrigation modes (conventional irrigation and 25% water-saved irrigation) and different N application rates (conventional high-nitrogen fertilization and 40% nitrogen-reduced fertilization) on microbial and microfauna assemblages at tillering and ripening stages in paddy field. The results showed that compared with conventional irrigation (CF), water-saved irrigation (WS) decreased the soil pH at tillering stage. Soil dissolved organic matter (dissolved organic C and N) and microbial biomass C and N were significantly affected by irrigation, nitrogen fertilizer and their interactions. WS or N-reduced fertilization (LN) decreased the contents of dissolved organic matter; WS increased microbial biomass C but decreased microbial biomass N. Nitrate was significantly higher in WS than CF, while ammonium showed reverse pattern. At tillering stage, the soil microbial biomass from bacteria, fungi, actinomy and protozoa was higher in WS than in CF, but the trend was opposite at ripening stage. There was a significant interation between irrigation and fertilization on soil rotifer numbers and microbial-feeding nematodes. At tillering stage, WS increased the numbers of rotifer and nematode, and also the proportion of bacterial-feeding nematode; LN increased the abundance of rotifer but decreased the abundance of nematode. In summary, soil microbial and microfauna assemblages showed different response to water-saved and nitrogen-reduced agricultural managements, which depended on different crop growth stages, but also the complex interactions of water and nitrogen and between biological groups in food webs.

  11. MICROBIAL MATS - A JOINT VENTURE

    NARCIS (Netherlands)

    VANGEMERDEN, H

    1993-01-01

    Microbial mats characteristically are dominated by a few functional groups of microbes: cyanobacteria, colorless sulfur bacteria, purple sulfur bacteria, and sulfate-reducing bacteria. Their combined metabolic activities result in steep environmental microgradients, particularly of oxygen and sulfid

  12. Influence of dormancy on microbial competition under intermittent substrate supply: insights from model simulations.

    Science.gov (United States)

    Stolpovsky, Konstantin; Fetzer, Ingo; Van Cappellen, Philippe; Thullner, Martin

    2016-06-01

    Most natural environments are characterized by frequent changes of their abiotic conditions. Microorganisms can respond to such changes by switching their physiological state between activity and dormancy allowing them to endure periods of unfavorable abiotic conditions. As a consequence, the competitiveness of microbial species is not simply determined by their growth performance under favorable conditions but also by their ability and readiness to respond to periods of unfavorable environmental conditions. The present study investigates the relevance of factors controlling the abundance and activity of individual bacterial species competing for an intermittently supplied substrate. For this purpose, numerical experiments were performed addressing the response of microbial systems to regularly applied feeding pulses. Simulation results show that community dynamics may exhibit a non-trivial link to the frequency of the external constraints and that for a certain combination of these environmental conditions coexistence of species is possible. The ecological implication of our results is that even non-dominant, neglected species can have a strong influence on realized species composition of dominant key species, due to their invisible presence enable the coexistence between important key species and by this affecting provided function of the system. PMID:27044984

  13. Influence of anthropogenic activities on microbial and nutrient levels along the Mara River tributaries, Kenya

    Directory of Open Access Journals (Sweden)

    Douglas Nyambane Anyona

    2014-05-01

    Full Text Available Background: A number of factors have a negative impact on natural surface water resources across the world. Although sources of surface water pollution are numerous, anthropogenic activities have been singled out as among the most important and of great concern. The aim of this study was to assess the influence of anthropogenic activities on nutrients and microbial levels along the Amala and Nyangores tributaries of the Mara River in Kenya. Materials and Methods: Four sampling sites along each tributary were specifically selected from which water samples were collected and analyzed for nutrients by use of spectrophotometric techniques, and coliform bacterial presence by a multiple tube fermentation technique. Results: Higher levels of total phosphorus were recorded along the Nyangores than the Amala tributary (P= 0.02. Significant differences in phosphorus levels were recorded between different sites along the Nyangores tributary (P=<0.001 and also along the Amala tributary (P= 0.0036. However, total nitrogen levels varied only within sites along the Nyangores tributary (P<0.0001 but not along the Amala tributary. Similarly, Escherichia coli and total coliform levels varied significantly within Nyangores tributary sites. Sites with frequent and direct human and livestock contact had higher microbial and nutrient levels, indicative of a localized pollution effect. Conclusion: The findings imply that the health of local communities who depend on this water for domestic use might be compromised. As such, regular monitoring, strict enforcement of environmental protection laws, public education and proper sewage disposal is recommended.

  14. Influence of ceramic separator’s characteristics on microbial fuel cell performance

    Directory of Open Access Journals (Sweden)

    Anil N. Ghadge

    2014-12-01

    Full Text Available This study aimed at evaluating the influence of clay properties on the performance of microbial fuel cell made using ceramic separators. Performance of two clayware microbial fuel cells (CMFCs made from red soil (CMFC-1 typically rich in aluminum and silica and black soil (CMFC-2 with calcium, iron and magnesium predominant was evaluated. These MFCs were operated under batch mode using synthetic wastewater. Maximum sustainable volumetric power density of 1.49 W m-3 and 1.12 W m-3 was generated in CMFC-1 and CMFC-2, respectively. During polarization, the maximum power densities normalized to anode surface area of 51.65 mW m-2 and 31.20 mW m-2 were obtained for CMFC-1 and CMFC-2, respectively. Exchange current densities at cathodes of CMFC-1 and CMFC-2 are 3.38 and 2.05 times more than that of respective anodes, clearly indicating that the cathodes supported much faster reaction than the anode. Results of laboratory analysis support the presence of more number of exchangeable cations in red soil, representing higher proton exchange capacity of CMFC-1 than CMFC-2. Higher power generation was observed for CMFC-1 with separator made of red soil. Hence, separators made of red soil were more suitable for fabrication of MFC to generate higher power.

  15. Effect of Host Media on Microbial Influenced Corrosion due to Desulfotomaculum nigrificans

    Science.gov (United States)

    Lata, Suman; Sharma, Chhaya; Singh, Ajay K.

    2013-04-01

    This article reports about the tests carried to investigate microbial-induced corrosion on stainless steels due to sulfate-reducing bacteria sp. Desulfotomaculum nigrificans in different host media. Stainless steel 304L, 316L, and 2205 were selected for the test. Modified Baar's media (BM), sodium chloride solution, and artificial sea water (SW) were used as test solutions in anaerobic conditions. Electrochemical polarization and immersion test were performed to estimate the extent of corrosion rate and pitting on stainless steels. SEM/EDS were used to study the details inside/outside pits formed on the corroded samples. Biofilm formed on corroded coupons was analyzed for its components by UV/Visible spectroscopy. Corrosion attack on the test samples was observed maximum in case of exposure to SW followed by NaCl solution, both having sulfide and chloride whereas stainless steel exposed to BM, having sulfide, showed minimum attack. Tendency of extracellular polymeric substances to bind metal ions is observed to be responsible for governing the extent of corrosion attack.

  16. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples.

    Science.gov (United States)

    Voordouw, Gerrit; Menon, Priyesh; Pinnock, Tijan; Sharma, Mohita; Shen, Yin; Venturelli, Amanda; Voordouw, Johanna; Sexton, Aoife

    2016-01-01

    Microbially-influenced corrosion (MIC) contributes to the general corrosion rate (CR), which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm), for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs based on weight loss and iron determination were in good agreement. Average CRs were 0.022 mm/yr for eight produced waters with high numbers (10(5)/ml) of acid-producing bacteria (APB), but no sulfate-reducing bacteria (SRB). Average CRs were 0.009 mm/yr for five central processing facility (CPF) waters, which had no APB or SRB due to weekly biocide treatment and 0.036 mm/yr for 2 CPF tank bottom sludges, which had high numbers of APB (10(6)/ml) and SRB (10(8)/ml). Hence, corrosion monitoring with carbon steel beads indicated that biocide treatment of CPF waters decreased the CR, except where biocide did not penetrate. The CR for incubations with 20 ml of a produced water decreased from 0.061 to 0.007 mm/yr when increasing the number of beads from 1 to 40. CRs determined with beads were higher than those with coupons, possibly also due to a higher weight of iron per unit volume used in incubations with coupons. Use of 1 ml syringe columns, containing carbon steel beads, and injected with 10 ml/day of SRB-containing medium for 256 days gave a CR of 0.11 mm/yr under flow conditions. The standard deviation of the distribution of residual bead weights, a measure for the unevenness of the corrosion, increased with increasing CR. The most heavily corroded beads showed significant pitting. Hence the use of uniformly sized carbon steel beads offers new opportunities for screening and monitoring of corrosion including determination of the distribution of corrosion rates, which allows

  17. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples

    Directory of Open Access Journals (Sweden)

    Gerrit eVoordouw

    2016-03-01

    Full Text Available Microbially-influenced corrosion (MIC contributes to the general corrosion rate (CR, which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm, for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs based on weight loss and iron determination were in good agreement. Average CRs were 0.022 mm/yr for 8 produced waters with high numbers (105/ml of acid-producing bacteria (APB, but no sulfate-reducing bacteria (SRB. Average CRs were 0.009 mm/yr for 5 central processing facility (CPF waters, which had no APB or SRB due to weekly biocide treatment and 0.036 mm/yr for 2 CPF tank bottom sludges, which had high numbers of APB (106/ml and SRB (108/ml. Hence, corrosion monitoring with carbon steel beads indicated that biocide treatment of CPF waters decreased the CR, except where biocide did not penetrate. The CR for incubations with 20 ml of a produced water decreased from 0.061 to 0.007 mm/yr when increasing the number of beads from 1 to 40. CRs determined with beads were higher than those with coupons, possibly also due to a higher weight of iron per unit volume used in incubations with coupons. Use of 1 ml syringe columns, containing carbon steel beads and injected with 10 ml/day of SRB-containing medium for 256 days gave a CR of 0.11 mm/yr under flow conditions. The standard deviation of the distribution of residual bead weights, a measure for the unevenness of the corrosion, increased with increasing CR. The most heavily corroded beads showed significant pitting. Hence the use of uniformly sized carbon steel beads offers new opportunities for screening and monitoring of corrosion including determination of the distribution of corrosion rates, which allows

  18. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples

    Science.gov (United States)

    Voordouw, Gerrit; Menon, Priyesh; Pinnock, Tijan; Sharma, Mohita; Shen, Yin; Venturelli, Amanda; Voordouw, Johanna; Sexton, Aoife

    2016-01-01

    Microbially-influenced corrosion (MIC) contributes to the general corrosion rate (CR), which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm), for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs based on weight loss and iron determination were in good agreement. Average CRs were 0.022 mm/yr for eight produced waters with high numbers (105/ml) of acid-producing bacteria (APB), but no sulfate-reducing bacteria (SRB). Average CRs were 0.009 mm/yr for five central processing facility (CPF) waters, which had no APB or SRB due to weekly biocide treatment and 0.036 mm/yr for 2 CPF tank bottom sludges, which had high numbers of APB (106/ml) and SRB (108/ml). Hence, corrosion monitoring with carbon steel beads indicated that biocide treatment of CPF waters decreased the CR, except where biocide did not penetrate. The CR for incubations with 20 ml of a produced water decreased from 0.061 to 0.007 mm/yr when increasing the number of beads from 1 to 40. CRs determined with beads were higher than those with coupons, possibly also due to a higher weight of iron per unit volume used in incubations with coupons. Use of 1 ml syringe columns, containing carbon steel beads, and injected with 10 ml/day of SRB-containing medium for 256 days gave a CR of 0.11 mm/yr under flow conditions. The standard deviation of the distribution of residual bead weights, a measure for the unevenness of the corrosion, increased with increasing CR. The most heavily corroded beads showed significant pitting. Hence the use of uniformly sized carbon steel beads offers new opportunities for screening and monitoring of corrosion including determination of the distribution of corrosion rates, which allows

  19. Influence of the Biliary System on Biliary Bacteria Revealed by Bacterial Communities of the Human Biliary and Upper Digestive Tracts.

    Science.gov (United States)

    Ye, Fuqiang; Shen, Hongzhang; Li, Zhen; Meng, Fei; Li, Lei; Yang, Jianfeng; Chen, Ying; Bo, Xiaochen; Zhang, Xiaofeng; Ni, Ming

    2016-01-01

    Biliary bacteria have been implicated in gallstone pathogenesis, though a clear understanding of their composition and source is lacking. Moreover, the effects of the biliary environment, which is known to be generally hostile to most bacteria, on biliary bacteria are unclear. Here, we investigated the bacterial communities of the biliary tract, duodenum, stomach, and oral cavity from six gallstone patients by using 16S rRNA amplicon sequencing. We found that all observed biliary bacteria were detectable in the upper digestive tract. The biliary microbiota had a comparatively higher similarity with the duodenal microbiota, versus those of the other regions, but with a reduced diversity. Although the majority of identified bacteria were greatly diminished in bile samples, three Enterobacteriaceae genera (Escherichia, Klebsiella, and an unclassified genus) and Pyramidobacter were abundant in bile. Predictive functional analysis indicated enhanced abilities of environmental information processing and cell motility of biliary bacteria. Our study provides evidence for the potential source of biliary bacteria, and illustrates the influence of the biliary system on biliary bacterial communities.

  20. Microbially influenced corrosion of stainless steel by marine bacterium Vibrio natriegens: (I) Corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Sha; Tian Jintao [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Chen Shougang, E-mail: sgchen@ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Lei Yanhua; Chang Xueting; Liu Tao [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China); Yin Yansheng, E-mail: yys2006@ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266100 (China)

    2009-04-30

    The microbially influenced corrosion of stainless steel (SS) by marine bacterium Vibrio natriegens (V. natriegens) was investigated using surface analysis (atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDXA)) and electrochemical techniques (the open circuit potential, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization curves ). AFM images corroborated the results from the EIS models which show biofilm attachment and subsequent detachment over time. The SEM images revealed the occurrence of micro-pitting corrosion underneath the biofilms on the metal surface after the biofilm removal. The presence of carbon, oxygen, phosphor and sulfur obtained from EDXA proved the formation of biofilm. The electrochemical results showed that the corrosion of SS was accelerated in the presence of V. natriegens based on the decrease in the resistance of the charge transfer resistance (R{sub ct}) obtained from EIS and the increase in corrosion current densities obtained from potentiodynamic polarization curves.

  1. Microbially influenced corrosion of stainless steels; Stainless ko no biseibutsu fushoku ni kansuru chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Y.; Misawa, M. [Kansai Electric Power Co. Inc., Osaka (Japan)

    1998-11-30

    It is generally known, though not fully clarified, that stainless steel pipes, particularly those exposed to natural sea water; are susceptible to microbially influenced corrosion (MIC) at welded joints. In an effort to gain a better understanding of the mechanism, factors affecting the MIC behavior in welded stainless steel pipe joints were experimentally investigated. Results of the study indicate there are two major contributing factors to MIC development in the weld region. One is the circumferentially protruding shape effect of the deposited metal, provinding an environment that allows aquatic microorganisms to adhere to the downstream side of the welded bead surface. The other factor is the declining corrosion resistance in the welded joint due to the oxide film formation caused by insufficient shielding during welding. There factors, if combined, produce higher susceptibility to MIC in the weld than in the base metal. (author)

  2. Microbially influenced corrosion of Fe-, Ni-, Cu-, Al-, and Ti-based weldments

    Energy Technology Data Exchange (ETDEWEB)

    Buchanan, R.A.; Kovacs, A.L.; Lundin, C.D.; Khan, K.K.; Danko, J.C. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Angell, P. [Southwest Research Inst., San Antonio, TX (United States); Dexter, S.C. [Univ. of Delaware, Lewes, DE (United States). Coll. of Marine Studies

    1997-06-01

    Weldments representative of a range of marine structural materials were exposed to a natural marine environment, which was known from previous studies to induce microbially influenced corrosion (MIC). The natural environment was at a University of Delaware site on the Delaware Bay, Lewes, Delaware. Companion laboratory control tests were conducted at the University of Tennessee in 0.2 {micro}m filtered Delaware Bay water and in synthetic seawater. The natural and control tests were conducted with weldments in both creviced and noncreviced conditions. Open-circuit potentials (OCPs) and corrosion rates (polarization-resistance measurements and microscopic examinations) were evaluated for all tests. The weldments studied were: UNS S30403 (304L), UNS S31603 (316L), and UNS N08367 (AL-6XN) stainless steels; HY-80 and K 11576 (HSLA-80) low-alloy steels; alloy 400 M-Cu alloy; 90-10 Cu-Ni alloy; 5086 aluminum alloy; and unalloyed titanium.

  3. An efficient screening method for the isolation of heterotrophic bacteria influencing growth of diatoms under photoautotrophic conditions.

    Science.gov (United States)

    Zecher, Karsten; Jagmann, Nina; Seemann, Philipp; Philipp, Bodo

    2015-12-01

    Interactions between photoautotrophic diatoms and heterotrophic bacteria are important for the biogeochemical C-cycle in the oceans. Additionally, biofilms formed by diatoms and bacteria are the initiating step of biofouling processes, which causes high costs in shipping. Despite this ecological and economical importance, the knowledge about biochemical and molecular mechanisms underlying these interkingdom interactions is relatively small. For analyzing these mechanisms, laboratory model systems are required. In this study, an efficient screening method for isolating bacteria influencing photoautotrophic diatom growth was established. First, diatom cultures of Phaeodactylum tricornutum and Thalassiosira pseudonana were made axenic by applying β-lactam antibiotics. Second, a non-invasive method for measuring growth of multiple parallel diatom cultures by chlorophyll fluorescence was established. This method allowed semi-quantitative chlorophyll determination of cultures with up to 3 μg (chlorophyll) ml(-1). Axenic diatom cultures were then used for enriching bacteria and led to the isolation of 24 strains influencing growth of both diatom strains in various ways. For example, Rheinheimera sp. strain Tn16 inhibited growth of T. pseudonana, while it stimulated growth and cell aggregation of P. tricornutum. Thus, this screening method is appropriate for isolating heterotrophic bacteria showing different interactions with different diatom species ranging from synergistic to antagonistic. In consecutive applications, this method will be useful to screen for bacterial mutants with altered phenotypes regarding the influence on diatom growth.

  4. Influence of management practices on microbial nitrogen cyclers in agricultural soils

    Science.gov (United States)

    García-Orenes, Fuensanta; Morugán-Coronado, Alicia; McMillan, Mary; Pereg, Lily

    2016-04-01

    Agricultural land management has great influences on soil properties, in particular on microbial communities, due to their sensitivity to the perturbations of the soils. This is even more relevant in Mediterranean agricultural areas under semi-arid conditions. The Mediterranean belt is suffering from an intense degradation of its soils due to the millennia of intense land use and due to unsustainable management practices. As a consequence this area is suffering from a depletion of N content. In this work we investigated the effect of several traditional agricultural management practices on specific functional groups related to the nitrogen cycle in the soil. A field experiment was performed with orchard orange trees (citrus sinesis) in Eastern Spain to assess the long-term effects of ploughing with inorganic fertilization (PI) and ecological practices (EP) (chipped pruned branches and weeds as well as manure from sheep and goats) on microbes that can undertake nitrogen fixation and denitrification. Nine samples of soil were taken from every treatment, near the drip irrigation point and in a zone without the influence of drip irrigation (between trees row), and total DNA extracted. DNA samples were stored at minus-20°C to be analysed by qPCR. Microbial populations involved in the N biochemical cycle were analysed by targeted amplification of key functional biomarker genes: the abundance of nifH (nitrogen fixation), nirS, nirK and nosZ (denitrification) detected by quantitative PCR (qPCR) has shown significant differences between treatments with higher abundance of all four genes in soils from ecological agricultural treatments. This may indicate that the ecological treatment created conditions that are more suitable for N cyclers in the soil and a better fertility and quality status of these soils.

  5. Influence of complement on neutrophil extracellular trap release induced by bacteria

    DEFF Research Database (Denmark)

    Palmer, Lisa Joanne; Damgaard, Christian; Holmstrup, Palle;

    2016-01-01

    by Staphylococcus aureus and three oral bacteria: Actinomyces viscosus, Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum subsp. vincettii. MATERIAL AND METHODS: Bacteria-stimulated NET release from the neutrophils of healthy donors was measured fluorometrically. Various complement containing....... Within biofilms, the complement-inactivating abilities of some bacteria may protect other species against NETosis, while these are more vulnerable when adopting a planktonic lifestyle....

  6. Microbial Enhanced Heavy Oil Recovery by the Aid of Inhabitant Spore-Forming Bacteria: An Insight Review

    OpenAIRE

    Biji Shibulal; Al-Bahry, Saif N.; Al-Wahaibi, Yahya M.; Elshafie, Abdulkader E.; Al-Bemani, Ali S.; Joshi, Sanket J.

    2014-01-01

    Crude oil is the major source of energy worldwide being exploited as a source of economy, including Oman. As the price of crude oil increases and crude oil reserves collapse, exploitation of oil resources in mature reservoirs is essential for meeting future energy demands. As conventional recovery methods currently used have become less efficient for the needs, there is a continuous demand of developing a new technology which helps in the upgradation of heavy crude oil. Microbial enhanced oil...

  7. Structural and chemical modification of Fe-rich smectite associated with microbial Fe-respiration by psychrophilic bacteria in King George Island, West Antarctica

    Science.gov (United States)

    Jung, J.; Kim, J. Y.; Lim, H. S.; Lee, Y. K.; Kim, O. S.; Park, K.; Lee, J.; Yoon, H.; Kim, J. W.

    2015-12-01

    Biotic/abiotic redox reaction is a ubiquitous process in a mineral alteration and an elemental cycling in the sediments/ocean. The role of psychrophiles in clay mineral alteration was tested in the soil for the seven sites from the coast to the inland at Barton Peninsula. Batch experiments of microbe-mineral interaction under the various temperatures (4 ℃, 15 ℃) that mimics the Antarctic condition were performed to understand the mechanism of biogeochemical alteration of clay minerals. After 12 months incubation of the bulk surface soil samples in the M1 minimal medium, the extent of Fe reduction was reached up to 49 and 42 % at 4 ℃ and 15 ℃. The increase in CEC corresponds to the extent of Fe reduction. Moreover, precipitations of secondary phase mineral such as vivianite were observed only in 12 months enrichment samples at 4 ℃ and 15 ℃. Sulfate reducing bacteria and Fe-reducing bacteria capable of reducing Fe were identified by 16S rRNA pyrosequencing. The Fe reduction coupled to oxidation of organic matter might be enhanced by cooperation of a consortium of Sulfate reducing bacteria and Fe-reducing bacteria. Moreover, Nitrate reducing bacteria which have an ability to oxidize ferrous iron anaerobically with nitrate reduction were identified at 15 ℃. The lower values observed in the extent of Fe reduction at 15 ℃ may be associated with Fe-oxidation induced by nitrate reduction.In order to verify the mechanism of microbial Fe reduction in clay minerals at low temperatures (4 and 15 ℃), Fe-rich Nontronite (NAu-1) and Psychrophilic bacteria were incubated for 4 months in anaerobic condition. Total structural Fe in NAu-1 is 16.4 % and 99.6 % of the total Fe is ferric. The extent of Fe reduction in nontronite was reached up to 11.5 % and 11 % at 4 ℃ and 15 ℃, respectively. The structural modification of biologically Fe-reduced nontronite was observed in the (001) peak shift to the lower 2 theta indicating the layer collapse associated with K

  8. Characterization of microbial associations with methanotrophic archaea and sulfate-reducing bacteria through statistical comparison of nested Magneto-FISH enrichments

    Science.gov (United States)

    Case, David H.

    2016-01-01

    Methane seep systems along continental margins host diverse and dynamic microbial assemblages, sustained in large part through the microbially mediated process of sulfate-coupled Anaerobic Oxidation of Methane (AOM). This methanotrophic metabolism has been linked to consortia of anaerobic methane-oxidizing archaea (ANME) and sulfate-reducing bacteria (SRB). These two groups are the focus of numerous studies; however, less is known about the wide diversity of other seep associated microorganisms. We selected a hierarchical set of FISH probes targeting a range of Deltaproteobacteria diversity. Using the Magneto-FISH enrichment technique, we then magnetically captured CARD-FISH hybridized cells and their physically associated microorganisms from a methane seep sediment incubation. DNA from nested Magneto-FISH experiments was analyzed using Illumina tag 16S rRNA gene sequencing (iTag). Enrichment success and potential bias with iTag was evaluated in the context of full-length 16S rRNA gene clone libraries, CARD-FISH, functional gene clone libraries, and iTag mock communities. We determined commonly used Earth Microbiome Project (EMP) iTAG primers introduced bias in some common methane seep microbial taxa that reduced the ability to directly compare OTU relative abundances within a sample, but comparison of relative abundances between samples (in nearly all cases) and whole community-based analyses were robust. The iTag dataset was subjected to statistical co-occurrence measures of the most abundant OTUs to determine which taxa in this dataset were most correlated across all samples. Many non-canonical microbial partnerships were statistically significant in our co-occurrence network analysis, most of which were not recovered with conventional clone library sequencing, demonstrating the utility of combining Magneto-FISH and iTag sequencing methods for hypothesis generation of associations within complex microbial communities. Network analysis pointed to many co

  9. Characterization of microbial associations with methanotrophic archaea and sulfate-reducing bacteria through statistical comparison of nested Magneto-FISH enrichments.

    Science.gov (United States)

    Trembath-Reichert, Elizabeth; Case, David H; Orphan, Victoria J

    2016-01-01

    Methane seep systems along continental margins host diverse and dynamic microbial assemblages, sustained in large part through the microbially mediated process of sulfate-coupled Anaerobic Oxidation of Methane (AOM). This methanotrophic metabolism has been linked to consortia of anaerobic methane-oxidizing archaea (ANME) and sulfate-reducing bacteria (SRB). These two groups are the focus of numerous studies; however, less is known about the wide diversity of other seep associated microorganisms. We selected a hierarchical set of FISH probes targeting a range of Deltaproteobacteria diversity. Using the Magneto-FISH enrichment technique, we then magnetically captured CARD-FISH hybridized cells and their physically associated microorganisms from a methane seep sediment incubation. DNA from nested Magneto-FISH experiments was analyzed using Illumina tag 16S rRNA gene sequencing (iTag). Enrichment success and potential bias with iTag was evaluated in the context of full-length 16S rRNA gene clone libraries, CARD-FISH, functional gene clone libraries, and iTag mock communities. We determined commonly used Earth Microbiome Project (EMP) iTAG primers introduced bias in some common methane seep microbial taxa that reduced the ability to directly compare OTU relative abundances within a sample, but comparison of relative abundances between samples (in nearly all cases) and whole community-based analyses were robust. The iTag dataset was subjected to statistical co-occurrence measures of the most abundant OTUs to determine which taxa in this dataset were most correlated across all samples. Many non-canonical microbial partnerships were statistically significant in our co-occurrence network analysis, most of which were not recovered with conventional clone library sequencing, demonstrating the utility of combining Magneto-FISH and iTag sequencing methods for hypothesis generation of associations within complex microbial communities. Network analysis pointed to many co

  10. The Influence of Ecological and Conventional Plant Production Systems on Soil Microbial Quality under Hops (Humulus lupulus

    Directory of Open Access Journals (Sweden)

    Karolina Oszust

    2014-06-01

    Full Text Available The knowledge about microorganisms—activity and diversity under hop production is still limited. We assumed that, different systems of hop production (within the same soil and climatic conditions significantly influence on the composition of soil microbial populations and its functional activity (metabolic potential. Therefore, we compared a set of soil microbial properties in the field experiment of two hop production systems (a ecological based on the use of probiotic preparations and organic fertilization (b conventional—with the use of chemical pesticides and mineral fertilizers. Soil analyses included following microbial properties: The total number microorganisms, a bunch of soil enzyme activities, the catabolic potential was also assessed following Biolog EcoPlates®. Moreover, the abundance of ammonia-oxidizing archaea (AOA was characterized by terminal restriction fragment length polymorphism analysis (T-RFLP of PCR ammonia monooxygenase α-subunit (amoA gene products. Conventional and ecological systems of hop production were able to affect soil microbial state in different seasonal manner. Favorable effect on soil microbial activity met under ecological, was more probably due to livestock-based manure and fermented plant extracts application. No negative influence on conventional hopyard soil was revealed. Both type of production fulfilled fertilizing demands. Under ecological production it was due to livestock-based manure fertilizers and fermented plant extracts application.

  11. Final Technical Report: DOE-Biological Ocean Margins Program. Microbial Ecology of Denitrifying Bacteria in the Coastal Ocean.

    Energy Technology Data Exchange (ETDEWEB)

    Lee Kerkhof

    2013-01-01

    The focus of our research was to provide a comprehensive study of the bacterioplankton populations off the coast of New Jersey near the Rutgers University marine field station using terminal restriction fragment polymorphism analysis (TRFLP) coupled to 16S rRNA genes for large data set studies. Our three revised objectives to this study became: (1) to describe bacterioplankton population dynamics in the Mid Atlantic Bight using TRFLP analysis of 16S rRNA genes. (2) to determine whether spatial and temporal factors are driving bacterioplankton community dynamics in the MAB using monthly samping along our transect line over a 2-year period. (3) to identify dominant members of a coastal bacterioplankton population by clonal library analysis of 16S rDNA genes and sequencing of PCR product corresponding to specific TRFLP peaks in the data set. Although open ocean time-series sites have been areas of microbial research for years, relatively little was known about the population dynamics of bacterioplankton communities in the coastal ocean on kilometer spatial and seasonal temporal scales. To gain a better understanding of microbial community variability, monthly samples of bacterial biomass were collected in 1995-1996 along a 34-km transect near the Long-Term Ecosystem Observatory (LEO-15) off the New Jersey coast. Surface and bottom sampling was performed at seven stations along a transect line with depths ranging from 1 to 35m (n=178). The data revealed distinct temporal patterns among the bacterioplankton communities in the Mid-Atlantic Bight rather than grouping by sample location or depth (figure 2-next page). Principal components analysis models supported the temporal patterns. In addition, partial least squares regression modeling could not discern a significant correlation from traditional oceanographic physical and phytoplankton nutrient parameters on overall bacterial community variability patterns at LEO-15. These results suggest factors not traditionally

  12. Factors Affecting Microbial Load and Profile of Potential Pathogens and Food Spoilage Bacteria from Household Kitchen Tables.

    Science.gov (United States)

    Biranjia-Hurdoyal, Susheela; Latouche, Melissa Cathleen

    2016-01-01

    The aim was to study the bacterial load and isolate potential pathogens and food spoilage bacteria from kitchen tables, including preparation tables and dining tables. Methods. A total of 53 households gave their consent for participation. The samples were collected by swabbing over an area of 5 cm by 5 cm of the tables and processed for bacterial count which was read as colony forming units (CFU), followed by isolation and identification of potential pathogens and food spoilage bacteria. Result. Knowledge about hygiene was not always put into practice. Coliforms, Enterococcus spp., Pseudomonas spp., Proteus spp., and S. aureus were detected from both dining and preparation tables. The mean CFU and presence of potential pathogens were significantly affected by the hygienic practices of the main food handler of the house, materials of kitchen tables, use of plastic covers, time of sample collection, use of multipurpose sponges/towels for cleaning, and the use of preparation tables as chopping boards (p Kitchen tables could be very important source of potential pathogens and food spoilage bacteria causing foodborne diseases. Lack of hygiene was confirmed by presence of coliforms, S. aureus, and Enterococcus spp. The use of plastic covers, multipurpose sponges, and towels should be discouraged. PMID:27446220

  13. Influence of microstructure on the microbial corrosion behaviour of stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, D. A.; Ibars, J. R.; Ranninger, C. [Universidad Politecnica de Madrid (Spain)

    2000-07-01

    Several stainless steels (Type UNS S30300, S30400, S30403; S31600, S31603 and S42000) with different microstructural characteristics have been used to study the influence of heat treatments on microbiologically influenced corrosion (MIC). Bio corrosion and accelerated electrochemical testing was performed in various microbiological media. Two species of sulphate-reducing bacteria (SRB) have been used in order to ascertain the influence of microstructure. The morphology of corrosion pits produced in both chloride and chloride plus sulphide-SRB metabolites, was inspected by optical and scanning electron microscopy (SEM) complemented with energy-dispersive X-ray (EDX) analysis. Results have shown different behaviours regarding corrosion resistance in each case studied. Sensitized austenitic stainless steels were more affected by the presence of aggressive anions and pitting potential (Ep) values were more cathodic than those of as-received state. A corrosion enhancement is produced by the synergistic action of biogenic sulphides and chloride anions. Pitting corrosion in martensitic stainless steel Type UNS S42000 was found in biocorrosion test. The pitting morphology is correlated to the chemical composition, the microstructure and the electrolyte. (Author) 36 refs.

  14. Influence of microstructure on the microbial corrosion behaviour of stainless steels

    International Nuclear Information System (INIS)

    Several stainless steels (Type UNS S30300, S30400, S30403; S31600, S31603 and S42000) with different microstructural characteristics have been used to study the influence of heat treatments on microbiologically influenced corrosion (MIC). Bio corrosion and accelerated electrochemical testing was performed in various microbiological media. Two species of sulphate-reducing bacteria (SRB) have been used in order to ascertain the influence of microstructure. The morphology of corrosion pits produced in both chloride and chloride plus sulphide-SRB metabolites, was inspected by optical and scanning electron microscopy (SEM) complemented with energy-dispersive X-ray (EDX) analysis. Results have shown different behaviours regarding corrosion resistance in each case studied. Sensitized austenitic stainless steels were more affected by the presence of aggressive anions and pitting potential (Ep) values were more cathodic than those of as-received state. A corrosion enhancement is produced by the synergistic action of biogenic sulphides and chloride anions. Pitting corrosion in martensitic stainless steel Type UNS S42000 was found in biocorrosion test. The pitting morphology is correlated to the chemical composition, the microstructure and the electrolyte. (Author) 36 refs

  15. Temperature and injection water source influence microbial community structure in four Alaskan North Slope hydrocarbon reservoirs.

    Directory of Open Access Journals (Sweden)

    Yvette Marisa Piceno

    2014-08-01

    Full Text Available A fundamental knowledge of microbial community structure in petroleum reservoirs can improve predictive modeling of these environments. We used hydrocarbon profiles, stable isotopes, and high-density DNA microarray analysis to characterize microbial communities in produced water from four Alaska North Slope hydrocarbon reservoirs. Produced fluids from Schrader Bluff (24-27°C, Kuparuk (47-70°C, Sag River (80°C, and Ivishak (80-83°C reservoirs were collected, with paired soured/non-soured wells sampled from Kuparuk and Ivishak. Chemical and stable isotope data suggested Schrader Bluff had substantial biogenic methane, whereas methane was mostly thermogenic in deeper reservoirs. Acetoclastic methanogens (Methanosaeta were most prominent in Schrader Bluff samples, and the combined δD and δ13C values of methane also indicated acetoclastic methanogenesis could be a primary route for biogenic methane. Conversely, hydrogenotrophic methanogens (e.g., Methanobacteriaceae and sulfide-producing Archaeoglobus and Thermococcus were more prominent in Kuparuk samples. Sulfide-producing microbes were detected in all reservoirs, uncoupled from souring status (e.g., the non-soured Kuparuk samples had higher relative abundances of many sulfate-reducers compared to the soured sample, suggesting sulfate-reducers may be living fermentatively/syntrophically when sulfate is limited. Sulfate abundance via long-term seawater injection resulted in greater relative abundances of Desulfonauticus, Desulfomicrobium, and Desulfuromonas in the soured Ivishak well compared to the non-soured well. In the non-soured Ivishak sample, several taxa affiliated with Thermoanaerobacter and Halomonas predominated. Archaea were not detected in the deepest reservoirs. Functional group taxa differed in relative abundance among reservoirs, likely reflecting differing thermal and/or geochemical influences.

  16. Thinning intensity influences on soil microbial and inorganic nitrogen in Pinus densiflora forests, central Korea

    Science.gov (United States)

    Kim, S.; Li, G.; Yun, H. M.; Han, S. H.; Lee, J.; Kim, C.; Lee, S. T.; Son, Y.

    2015-12-01

    With growing considerations for sustainable forest management, examining thinning effects on forest ecosystems becomes one of the principal research focuses. Soil microbial biomass and inorganic nitrogen (N) have, particularly, received increasing attentions, as they are the relevant indices for N availability in forests. Here, we investigated the influences of thinning on soil microbial biomass N (MBN) and inorganic N (NH4+ and NO3-) in two Pinus densiflora forests, central Korea. The thinning from below with different intensities based on stand density (site 1: control, 20%, and 30% thinning; site 2: control, 39%, and 74% thinning) was applied in 2008, and MBN, NH4+, and NO3- at 0-10 cm depth were measured seven years after thinning. The MBN, NH4+, and NO3- concentrations (mg kg-1) of the site 1 were 69.8, 9.8, and 6.3 in the control, 94.6, 9.3, and 4.0 in the 20% thinning plot, and 97.2, 8.4, and 5.2 in the 30% thinning plot, respectively. On the other hand, those of the site 2 were 34.5, 5.4, and 6.3 in the control, 37.3, 4.7, and 7.8 in the 39% thinning plot, and 44.4, 4.4, and 9.2 in the 74% thinning plot, respectively. The MBN of the thinning plots tended to be higher compared to those of the controls, although the analysis of variance reported the significant difference only for the MBN in the site 1 (P0.05). The results of the present study show that the application of thinning could differently affect MBN and inorganic N; accordingly, this difference might alter N availability of the study sites. This study was supported by Forest Practice Research Center, Korea Forest Research Institute.

  17. Biomarkers of sulfate reducing bacteria from a variety of different aged samples including a modern microbial mat

    Science.gov (United States)

    Pages, A.; Grice, K.; Lockhart, R.; Holman, A.; Melendez, I.; Van Kranendonk, M.; Jaraula, C.

    2011-12-01

    Most biomarkers present in sediments occur in only trace concentrations, trapped in kerogen or may be highly functionalised especially in recent sedimentary deposits making them difficult to chromatographically resolve, thus presenting considerable analytical challenges, especially for isotope studies. Innovative hydro (Hy) pyrolysis (Py) techniques are able to target or convert many of these compounds into free hydrocarbons more amenable to gas chromatography mass-spectrometry (GC-MS) and compound-specific isotope analysis (CSIA). HyPy has been applied to a modern layered smooth mat from Shark Bay, Western Australia. Saturate and aromatic fractions from different layers of the mat have been analysed by GC-MS and CSIA. After HyPy, an even-odd distribution of n-alkanes has been revealed as well as very long-chain n-alkanes up to n-C38. Stable carbon isotopic values of the n-alkanes indicated the presence of at least two bacterial communities. The short-chain n-alkanes were likely to be representative of a cyanobacteria community (δ13C, C15-C23, - 18 to -25 %VPDB) while the carbon isotopic values of the long-chain n-alkanes supported the presence of sulfate reducing bacteria (δ13C, C25-C33, - 30 to - 34 %VPDB). Long-chain fatty acids have been previously reported in sulfate reducing bacteria. It is hypothesised that this distribution and isotopic character representing sulfate reducing bacteria consortia may be preserved in the rock record. This hypothesis has been tested in Australian rocks: a Devonian carbonaceous concretion containing an exceptionally well preserved fossil invertebrate from the Canning Basin, Western Australia, a Paleoproterozoic sample (1.6 billion years old) from a lead-zinc ore deposit from the McArthur Basin, Northern Territories and a Paleoproterozoic chert (2.3 billion years old) from the Pilbara, Western Australia. Biomarkers of these samples showed a strong predominance of long-chain n-alkanes, up to n-C38 with an even-odd distribution

  18. Influence of roadside pollution on the phylloplane microbial community of Alnus nepalensis (Betulaceae).

    Science.gov (United States)

    Joshi, S R

    2008-09-01

    The North Eastern region of India is undergoing industrial development at a faster rate than expected. Roads form the main system of transportation and communication owing to the hilly topography of the region. Automobiles discharge a number of gaseous and trace metal contaminants. Human activities like stone grinding, road construction and sand milling also increase the atmospheric dust and heavy metal contaminant level. These contaminants get settled on leaf surfaces at roadsides and enter in contact with phylloplane microorganisms. This study compares microorganisms on leaf surfaces of alder (Alnus nepalensis (Betulaceae)) on roadside and non-roadside environments. Two sites dominated by alder were selected. One at a busy road intersection on the National Highway no. 44 in Shillong with high traffic density (8 000-9 000 heavy vehicles/day), taken as the polluted site and the other one in a forest approximately 500 m away from the roadside considered as the unpolluted site. Analysis of phylloplane microorganisms, lead, zinc, copper, cadmium and sulphur was carried out from leaves. The bacterial population was higher at the unpolluted site. Bacterial population showed a significant negative correlation with lead, zinc, copper, cadmium and sulphur. Similarly, fungal population was higher at the unpolluted site. A total of 29 fungal species were isolated from the phylloplane of A. nepalensis (polluted site 16 species; unpolluted site 28 species). Some fungal forms like Mortierella sp., Fusarium oxysporum and Aureobasidium pollulans were dominant in the polluted site. Numbers of phylloplane fungi and bacteria were significantly reduced in the polluted site. The correlation coefficient indicated a detrimental effect of metals like lead, zinc, copper, cadmium and sulphur on the microbial community of leaf surfaces. The specificity of certain fungi to the unpolluted site may be attributed to their sensitivity to pollution. The predominance of Aureobasidium pollulans

  19. The Influence of Mineral Fertilizer Combined With a Nitrification Inhibitor on Microbial Populations and Activities in Calcareous Uzbekistanian Soil Under Cotton Cultivation

    Directory of Open Access Journals (Sweden)

    Dilfuza Egamberdiyeva

    2001-01-01

    Full Text Available Application of fertilizers combined with nitrification inhibitors affects soil microbial biomass and activity. The objective of this research was to determine the effects of fertilizer application combined with the nitrification inhibitor potassium oxalate (PO on soil microbial population and activities in nitrogen-poor soil under cotton cultivation in Uzbekistan. Fertilizer treatments were N as urea, P as ammophos, and K as potassium chloride. The nitrification inhibitor PO was added to urea and ammophos at the rate of 2%. Three treatments—N200P140K60 (T1, N200 P140 POK60 (T2, and N200 P140 POK60 (T3 mg kg-1 soil—were applied for this study. The control (C was without fertilizer and PO. The populations of oligotrophic bacteria, ammonifying bacteria, nitrifying bacteria, denitrifying bacteria, mineral assimilating bacteria, oligonitrophilic bacteria, and bacteria group Azotobacter were determined by the most probable number method. The treatments T2 and T3 increased the number of oligonitrophilic bacteria and utilization mineral forms of nitrogen on the background of reducing number of ammonifying bacteria. T2 and T3 also decreased the number of nitrifying bacteria, denitrifying bacteria, and net nitrification. In conclusion, our experiments showed that PO combined with mineral fertilizer is one of the most promising compounds for inhibiting nitrification rate, which was reflected in the increased availability and efficiency of fertilizer nitrogen to the cotton plants. PO combined with mineral fertilizer has no negative effects on nitrogen-fixing bacteria Azotobacter and oligo-nitrophilic bacteria.

  20. Lactic Acid Bacteria Improves Peyer's Patch Cell-Mediated Immunoglobulin A and Tight-Junction Expression in a Destructed Gut Microbial Environment.

    Science.gov (United States)

    Kim, Sung Hwan; Jeung, Woonhee; Choi, Il-Dong; Jeong, Ji-Woong; Lee, Dong Eun; Huh, Chul-Sung; Kim, Geun-Bae; Hong, Seong Soo; Shim, Jae-Jung; Lee, Jung Lyoul; Sim, Jae-Hun; Ahn, Young-Tae

    2016-06-28

    To evaluate the effects of lactic acid bacteria (LAB) on Peyer's patch cells, mice were treated with a high dose of kanamycin to disturb the gut microbial environment. The overarching goal was to explore the potential of LAB for use as a dietary probiotic that buffers the negative consequences of antibiotic treatment. In vitro, LAB stimulated the production of immunoglobulin A (IgA) from isolated Peyer's patch cells. Inflammation-related genes (TNF-α, IL-1β, and IL-8) were up-regulated in Caco-2 cells stimulated with lipopolysaccharide (LPS), while tight-junction-related genes (ZO-1 and occludin) were down-regulated; the effects of LPS on inflammatory gene and tight-junction gene expression were reversed by treatment with LAB. Mice treated with a high dose of kanamycin showed increased serum IgE levels and decreases in serum IgA and fecal IgA levels; the number of Peyer's patch cells decreased with kanamycin treatment. However, subsequent LAB treatment was effective in reducing the serum IgE level and recovering the serum IgA and fecal IgA levels, as well as the number of Peyer's patch cells. In addition, ZO-1 and occludin mRNA levels were up-regulated in the ileum tissues of mice receiving LAB treatment. Lactic acid bacteria can enhance the intestinal immune system by improving the integrity of the intestinal barrier and increasing the production of IgA in Peyer's patches. Lactic acid bacteria should be considered a potential probiotic candidate for improving intestinal immunity, particularly in mitigating the negative consequences of antibiotic use. PMID:26975767

  1. Quantification of Tinto River sediment microbial communities: importance of sulfate-reducing bacteria and their role in attenuating acid mine drainage.

    Science.gov (United States)

    Sánchez-Andrea, Irene; Knittel, Katrin; Amann, Rudolf; Amils, Ricardo; Sanz, José Luis

    2012-07-01

    Tinto River (Huelva, Spain) is a natural acidic rock drainage (ARD) environment produced by the bio-oxidation of metallic sulfides from the Iberian Pyritic Belt. This study quantified the abundance of diverse microbial populations inhabiting ARD-related sediments from two physicochemically contrasting sampling sites (SN and JL dams). Depth profiles of total cell numbers differed greatly between the two sites yet were consistent in decreasing sharply at greater depths. Although catalyzed reporter deposition fluorescence in situ hybridization with domain-specific probes showed that Bacteria (>98%) dominated over Archaea (important differences were detected at the class and genus levels, reflecting differences in pH, redox potential, and heavy metal concentrations. At SN, where the pH and redox potential are similar to that of the water column (pH 2.5 and +400 mV), the most abundant organisms were identified as iron-reducing bacteria: Acidithiobacillus spp. and Acidiphilium spp., probably related to the higher iron solubility at low pH. At the JL dam, characterized by a banded sediment with higher pH (4.2 to 6.2), more reducing redox potential (-210 mV to 50 mV), and a lower solubility of iron, members of sulfate-reducing genera Syntrophobacter, Desulfosporosinus, and Desulfurella were dominant. The latter was quantified with a newly designed CARD-FISH probe. In layers where sulfate-reducing bacteria were abundant, pH was higher and redox potential and levels of dissolved metals and iron were lower. These results suggest that the attenuation of ARD characteristics is biologically driven by sulfate reducers and the consequent precipitation of metals and iron as sulfides.

  2. Dissimilar Fitness Associated with Resistance to Fluoroquinolones Influences Clonal Dynamics of Various Multiresistant Bacteria.

    Science.gov (United States)

    Fuzi, Miklos

    2016-01-01

    Fitness cost associated with resistance to fluoroquinolones was recently shown to vary across clones of methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase-producing Klebsiella pneumoniae. The resulting dissimilar fitness should have influenced the clonal dynamics and thereby the rates of resistance for these pathogens. Moreover, a similar mechanism was recently proposed for the emergence of the H30 and H30R lineages of ESBL-producing E. coli and the major international clone (ribotype 027) of Clostridium difficile. Furthermore, several additional international clones of various multiresistant bacteria are suspect to have been selected by an analogous process. An ability to develop favorable mutations in the gyrase and topoisomerase IV genes seems to be a prerequisite for pathogens to retain fitness while showing high-level resistance to fluoroquinolones. Since, the consumption of other "non-fluoroquinolone" groups of antibiotics have also contributed to the rise in resistance rates a more judicious use of antibiotics in general and of fluoroquinolones in particular could ameliorate the international resistance situation. PMID:27458434

  3. Metallic copper corrosion rates, moisture content, and growth medium influence survival of copper ion-resistant bacteria

    DEFF Research Database (Denmark)

    Elguindi, J; Moffitt, S; Hasman, Henrik;

    2010-01-01

    The rapid killing of various bacteria in contact with metallic copper is thought to be influenced by the influx of copper ions into the cells, but the exact mechanism is not fully understood. This study showed that the kinetics of contact killing of copper surfaces depended greatly on the amount...... of moisture present, copper content of alloys, type of medium used, and type of bacteria. We examined antibiotic- and copper ion-resistant strains of Escherichia coli and Enterococcus faecium isolated from pig farms following the use of copper sulfate as feed supplement. The results showed rapid killing...

  4. Different influences of cadmium on soil microbial activity and structure with Chinese cabbage cultivated and non-cultivated

    Energy Technology Data Exchange (ETDEWEB)

    Liao Min; Ma Aili; Peng Ying [Dept. of Resources Science, Zhejiang Univ., Hangzhou (China); Zhejiang Provincial Key Lab. of Subtropical Soil and Plant Nutrition, Hangzhou (China); Xie Xiaomei [Research Center for Eco-Environmental Sciences, Zhejiang Univ., Hangzhou (China)

    2010-07-15

    Gram-positive to Gram-negative bacteria which were responsible for these differences with increasing Cd concentration in the planted and unplanted soils. Conclusions: Soil microbial parameters, including, soil C{sub mic}, the ratio of C{sub mic}/C{sub org}, qCO{sub 2}, and community structure, may be sensitive indicators reflecting environmental stress in soil-Cd-plant system. However, further research work is needed for better understanding the changes in microbial community structure and actually impact on soil microbial community function. (orig.)

  5. Influence of aeolian activities on the distribution of microbial abundance in glacier ice

    Directory of Open Access Journals (Sweden)

    Y. Chen

    2014-10-01

    Full Text Available Microorganisms are continuously blown onto the glacier snow, and thus the glacial depth profiles provide excellent archives of microbial communities and climatic and environmental changes. However, it is uncertain about how aeolian processes that cause climatic changes control the distribution of microorganisms in the glacier ice. In the present study, microbial density, stable isotopic ratios, 18O / 16O in the precipitation, and mineral particle concentrations along the glacial depth profiles were collected from ice cores from the Muztag Ata glacier and the Dunde ice cap. The ice core data showed that microbial abundance was often, but not always associated with high concentrations of particles. Results also revealed clear seasonal patterning with high microbial abundance occurring in both the cooling autumn and warming spring-summer seasons. Microbial comparisons among the neighbouring glaciers display a heterogeneous spatial pattern, with the highest microbial cell density in the glaciers lying adjacent to the central Asian deserts and lowest microbial density in the southwestern margin of the Tibetan Plateau. In conclusion, microbial data of the glaciers indicates the aeolian deposits of microorganisms in the glacier ice and that the spatial patterns of microorgansisms are related to differences in sources of microbial flux and intensity of aeolian activities in the current regions. The results strongly support our hypothesis of aeolian activities being the main agents controlling microbial load in the glacier ice.

  6. Microbial and chemical factors influencing methane production in laboratory incubations of low-rank subsurface coals

    Science.gov (United States)

    Harris, Stephen H.; Smith, Richard L.; Barker, Charles E.

    2008-01-01

    Lignite and subbituminous coals were investigated for their ability to support microbial methane production in laboratory incubations. Results show that naturally-occurring microorganisms associated with the coals produced substantial quantities of methane, although the factors influencing this process were variable among different samples tested. Methanogenic microbes in two coals from the Powder River Basin, Wyoming, USA, produced 140.5-374.6 mL CH4/kg ((4.5-12.0 standard cubic feet (scf)/ton) in response to an amendment of H2/CO2. The addition of high concentrations (5-10 mM) of acetate did not support substantive methane production under the laboratory conditions. However, acetate accumulated in control incubations where methanogenesis was inhibited, indicating that acetate was produced and consumed during the course of methane production. Acetogenesis from H2/CO2 was evident in these incubations and may serve as a competing metabolic mode influencing the cumulative amount of methane produced in coal. Two low-rank (lignite A) coals from Fort Yukon, Alaska, USA, demonstrated a comparable level of methane production (131.1-284.0 mL CH4/kg (4.2-9.1 scf/ton)) in the presence of an inorganic nutrient amendment, indicating that the source of energy and organic carbon was derived from the coal. The concentration of chloroform-extractable organic matter varied by almost three orders of magnitude among all the coals tested, and appeared to be related to methane production potential. These results indicate that substrate availability within the coal matrix and competition between different groups of microorganisms are two factors that may exert a profound influence on methanogenesis in subsurface coal beds.

  7. The Effect of Bicarbonate on the Microbial Dissolution of Autunite Mineral in the Presence of Gram-Positive Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda-Medina, Paola; Katsenovich, Yelena; Wellman, Dawn M.; Lagos, Leonel

    2015-06-01

    Bacteria are key players in the processes that govern fate and transport of contaminants. The uranium release from Na and Ca-autunite by Arthrobacter oxydans strain G968 was evaluated in the presence of bicarbonate ions. This bacterium was previously isolated from Hanford Site soil and in earlier prescreening tests demonstrated low tolerance to U(VI) toxicity compared to other A.oxydans isolates. Experiments were conducted using glass serum bottles as mixed bioreactors and sterile 6-well cell culture plates with inserts separating bacteria cells from mineral solids. Reactors containing phosphorus-limiting media were amended with bicarbonate ranging between 0-10 mM and metaautunite solids to provide a U(VI) concentration of 4.4 mmol/L. Results showed that in the presence of bicarbonate, A.oxydans G968 was able to enhance the release of U(VI) from Na and Ca autunite at the same capacity as other A.oxydans isolates with relatively high tolerance to U(VI). The effect of bacterial strains on autunite dissolution decreases as the concentration of bicarbonate increases. The results illustrate that direct interaction between the bacteria and the mineral is not necessary to result in U (VI) biorelease from autunite. The formation of secondary calcium-phosphate mineral phases on the surface of the mineral during the dissolution can ultimately reduce the natural autunite mineral contact area, which bacterial cells can access. This thereby reduces the concentration of uranium released into the solution. This study provides a better understanding of the interactions between meta-autunite and microbes in conditions mimicking arid and semiarid subsurface environments of western U.S.

  8. Examining microbial community response to a strong chemical gradient: the effects of surface coal mining on stream bacteria

    Science.gov (United States)

    Bier, R.; Lindberg, T. T.; Wang, S.; Ellis, J. C.; Di Giulio, R. T.; Bernhardt, E. S.

    2012-12-01

    Surface coal mining is the dominant form of land cover change in northern and central Appalachia. In this process, shallow coal seams are exposed by removing overlying rock with explosives. The resulting fragmented carbonate rock and coal residues are disposed of in stream valleys. These valley fills generate alkaline mine drainage (AlkMD), dramatically increasing alkalinity, ionic strength, substrate supply (esp. SO42-), and trace element (Mn, Li, Se, U) concentrations in downstream rivers as well as significant losses of sensitive fish and macroinvertebrate species. In prior work within the Mud River, which drains the largest surface mine complex in Appalachia, we found that concentrations of AlkMD increase proportionally with the extent of upstream mining. Here we ask "How do stream microbial communities change along this strong chemical gradient?" We collected surface water and benthic biofilms from 25 stream reaches throughout the Mud River spanning the full range of surface mining impacts, with 0-96% of the contributing watershed area converted to surface coal mines. Microbial communities were collected from biofilms grown on a common substrate (red maple veneers) that were incubated in each stream reach for four months prior to collection in April, 2011. 16S rRNA genes from microbial communities at each study site were examined using 454 sequencing and compared with a generalized UniFrac distance matrix (674 sequence eveness) that was used in statistical analyses. Water chemistry at the sites was sampled monthly from July 2010 to December 2010 and again in April 2011. In April, surface water concentrations of SO42-, Ca2+, Mg2+, and Se2- increased linearly with the extent of upstream mining (all regressions R2 >0.43; pmine drainage and those that were unexposed (NMDS ordination R2 =0.86; PERMANOVA; p=0.029). Bacterial diversity (OTU richness defined at 3% sequence difference) peaked at intermediate conductivities (600 μS cm-1). Environmental data that

  9. Influence of three bacteria strains on the population dynamics of Tisbe holothuriae (Copepoda, Harpacticoida)

    Science.gov (United States)

    Guérin, J.-P.; Rieper-Kirchner, M.

    1991-12-01

    The influence of three bacteria strains (Helgo 21, NCMB 308 and NCMB 13) on the life cycle of Tisbe holothuriae Humes 1957 was investigated under constant experimental conditions (19 20°C and 38‰ S). For each of the first six experiments, females (F1), whose life history was followed, were obtained from a common mother (F0). Experiment no 7 was carried out with adult females (F2) obtained during exp. 4. Females were bred in 50-ml dishes and transferred to a fresh container as soon as they produced a new egg-sac. Offspring (F2: exp. 1 6; F3: exp. 7) from successive egg-layings were counted as soon as they moulted into adults. Larval mortality was estimated by enumeration of the adults issuing from a known number of nauplii that had been fed different bacteria strains. Some difficulties arose in obtaining adults with NCMB 13: it appeared to be necessary to provide this first generation with a small quantity of TetraMin (commercial fish food) in order to initiate reproduction and obtain a second generation. However, in exp. 4, F2 adult females fed NCMB 13 became ovigerous and fertile without needing TetraMin. This result is interpreted as denoting an indispensable period of adaptation to the diet, which probably requires important changes at the enzymatic level. One experiment was carried out with Helgo 21; another one with NCMB 308; two with NCMB 13 (with a unique additional meal of TetraMin to allow reproduction), two with NCMB 13 during larval development, then only tetraMin during adult stage, and one with NCMB 13 alone (with females issued from exp. 4). Data obtained regarding longevity, duration of reproduction period, number of egg-sacs and number of adult descendants show an important variability between bacteria strains. Lower results were almost always obtained with Helgo 21 and NCMB 308. An interesting result lies in the maximum number of egg-sacs: low with Helgo 21 and NCMB 308 (5), but very ample with NCMB 13 (11 in one experiment). In experiment 7

  10. Microbial alterations of the soil influenced by induced compaction Alterações microbianas do solo influenciadas por compactação induzida

    Directory of Open Access Journals (Sweden)

    Breno Pupin

    2009-10-01

    Full Text Available Compaction is one of the most destructive factors of soil quality, however the effects on the microbial community and enzyme activity have not been investigated in detail so far. The objective of this study was to evaluate the effects of soil compaction caused by the traffic of agricultural machines on the soil microbial community and its enzyme activity. Six compaction levels were induced by tractors with different weights driving over a Eutrustox soil and the final density was measured. Soil samples were collected after corn from the layers 0-0.10 and 0.10-0.20 m. The compaction effect on all studied properties was evident. Total bacteria counts were reduced significantly (by 22-30 % and by 38-41 % of nitrifying bacteria in the soil with highest bulk density compared to the control. On the other hand, fungi populations increased 55-86 % and denitrifying bacteria 49-53 %. Dehydrogenase activity decreased 20-34 %, urease 44-46 % and phosphatase 26-28 %. The organic matter content and soil pH decreased more in the 0-0.10 than in the 0.10-0.20 m layer and possibly influenced the reduction of the microbial counts, except denitrifying bacteria, and all enzyme activities, except urease. Results indicated that soil compaction influences the community of aerobic microorganisms and their activity. This effect can alter nutrient cycling and reduce crop yields.A compactação é um dos fatores mais agravantes para a qualidade do solo, porém o seu efeito na comunidade e atividade enzimática microbiana não tem sido suficientemente estudado. Seis níveis de compactação foram obtidos pela passagem de tratores com diferentes pesos em um Latossolo Vermelho, e a densidade final foi medida. Amostras de solo foram coletadas nas profundidades de 0-10 e 10-20 cm, após a colheita do milho. O efeito da compactação foi evidente em todos os parâmetros estudados, mas nem sempre foi significativo. A contagem das bactérias totais reduziu significativamente em 22

  11. Bacteria, viruses, and parasites in an intermittent stream protected from and exposed to pasturing cattle: prevalence, densities, and quantitative microbial risk assessment.

    Science.gov (United States)

    Wilkes, G; Brassard, J; Edge, T A; Gannon, V; Jokinen, C C; Jones, T H; Neumann, N; Pintar, K D M; Ruecker, N; Schmidt, P J; Sunohara, M; Topp, E; Lapen, D R

    2013-10-15

    Over 3500 individual water samples, for 131 sampling times, targeting waterborne pathogens/fecal indicator bacteria were collected during a 7-year period from 4 sites along an intermittent stream running through a small livestock pasture system with and without cattle access-to-stream restriction measures. The study assessed the impact of cattle pasturing/riparian zone protection on: pathogen (bacterial, viral, parasite) occurrence, concentrations of fecal indicators, and quantitative microbial risk assessments (QMRA) of the risk of Cryptosporidium, Giardia and Escherichia coli O157:H7 infection in humans. Methodologies were developed to compute QMRA mean risks on the basis of water samples exhibiting potentially human infectious Cryptosporidium and E. coli based on genotyping Crytosporidium, and E. coli O157:H7 presence/absence information paired with enumerated E. coli. All Giardia spp. were considered infectious. No significant pasturing treatment effects were observed among pathogens, with the exception of Campylobacter spp. and E. coli O157:H7. Campylobacter spp. prevalence significantly decreased downstream through pasture treatments and E. coli O157:H7 was observed in a few instances in the middle of the unrestricted pasture. Densities of total coliform, fecal coliform, and E. coli reduced significantly downstream in the restricted pasture system, but not in the unrestricted system. Seasonal and flow conditions were associated with greater indicator bacteria densities, especially in the summer. Norovirus GII was detected at rates of 7-22% of samples for all monitoring sites, and rotavirus in 0-7% of samples for all monitoring sites; pasture treatment trends were not evident, however. Seasonal and stream flow variables (and their interactions) were relatively more important than pasture treatments for initially stratifying pathogen occurrence and higher fecal indicator bacteria densities. Significant positive associations among fecal indicator bacteria and

  12. Microbial processes and community composition in the rhizosphere of European beech – The influence of plant C exudates

    OpenAIRE

    Koranda, Marianne; Schnecker, Jörg; Kaiser, Christina; Fuchslueger, Lucia; Kitzler, Barbara; Stange, Claus Florian; Sessitsch, Angela; Zechmeister-Boltenstern, Sophie; Richter, Andreas

    2011-01-01

    Plant roots strongly influence C and N availability in the rhizosphere via rhizodeposition and uptake of nutrients. This study aimed at investigating the effect of resource availability on microbial processes and community structure in the rhizosphere. We analyzed C and N availability, as well as microbial processes and microbial community composition in rhizosphere soil of European beech and compared it to the bulk soil. Additionally, we performed a girdling experiment in order to disrupt ro...

  13. Influence of Environmental Factors on Phage-Bacteria Interaction and on the Efficacy and Infectivity of Phage P100.

    Science.gov (United States)

    Fister, Susanne; Robben, Christian; Witte, Anna K; Schoder, Dagmar; Wagner, Martin; Rossmanith, Peter

    2016-01-01

    When using bacteriophages to control food-borne bacteria in food production plants and processed food, it is crucial to consider that environmental conditions influence their stability. These conditions can also affect the physiological state of bacteria and consequently host-virus interaction and the effectiveness of the phage ability to reduce bacteria numbers. In this study we investigated the stability, binding, and replication capability of phage P100 and its efficacy to control Listeria monocytogenes under conditions typically encountered in dairy plants. The influences of SDS, Lutensol AO 7, salt, smear water, and different temperatures were investigated. Results indicate that phage P100 is stable and able to bind to the host under most conditions tested. Replication was dependent upon the growth of L. monocytogenes and efficacy was higher when bacterial growth was reduced by certain environmental conditions. In long-term experiments at different temperatures phages were initially able to reduce bacteria up to seven log10 units after 2 weeks at 4°C. However, thereafter, re-growth and development of phage-resistant L. monocytogenes isolates were encountered. PMID:27516757

  14. Influence of environmental factors on phage-bacteria interaction and on the efficacy and infectivity of phage P100

    Directory of Open Access Journals (Sweden)

    Susanne Fister

    2016-07-01

    Full Text Available When using bacteriophages to control food-borne bacteria in food production plants and processed food, it is crucial to consider that environmental conditions influence their stability. These conditions can also affect the physiological state of bacteria and consequently host-virus interaction and the effectiveness of the phage ability to reduce bacteria numbers. In this study we investigated the stability, binding and replication capability of phage P100 and its efficacy to control L. monocytogenes under conditions typically encountered in dairy plants. The influences of SDS, Lutensol AO 7, salt, smear water and different temperatures were investigated. Results indicate that phage P100 is stable and able to bind to the host under most conditions tested. Replication was dependent upon the growth of L. monocytogenes and efficacy was higher when bacterial growth was reduced by certain environmental conditions. In long-term experiments at different temperatures phages were initially able to reduce bacteria up to seven log10 units after two weeks at 4 °C. However, thereafter re-growth and development of phage-resistant L. monocytogenes isolates were encountered.

  15. Influence of Environmental Factors on Phage–Bacteria Interaction and on the Efficacy and Infectivity of Phage P100

    Science.gov (United States)

    Fister, Susanne; Robben, Christian; Witte, Anna K.; Schoder, Dagmar; Wagner, Martin; Rossmanith, Peter

    2016-01-01

    When using bacteriophages to control food-borne bacteria in food production plants and processed food, it is crucial to consider that environmental conditions influence their stability. These conditions can also affect the physiological state of bacteria and consequently host–virus interaction and the effectiveness of the phage ability to reduce bacteria numbers. In this study we investigated the stability, binding, and replication capability of phage P100 and its efficacy to control Listeria monocytogenes under conditions typically encountered in dairy plants. The influences of SDS, Lutensol AO 7, salt, smear water, and different temperatures were investigated. Results indicate that phage P100 is stable and able to bind to the host under most conditions tested. Replication was dependent upon the growth of L. monocytogenes and efficacy was higher when bacterial growth was reduced by certain environmental conditions. In long-term experiments at different temperatures phages were initially able to reduce bacteria up to seven log10 units after 2 weeks at 4°C. However, thereafter, re-growth and development of phage-resistant L. monocytogenes isolates were encountered. PMID:27516757

  16. Microbial population in the rumen of swamp buffalo (Bubalus bubalis) as influenced by coconut oil and mangosteen peel supplementation.

    Science.gov (United States)

    Pilajun, R; Wanapat, M

    2013-06-01

    Four, rumen fistulated swamp buffalo bulls were used to study microbial populations in the rumen when supplemented with coconut oil and mangosteen peel. Animals were randomly assigned to a 4 × 4 Latin square design. Four treatments were un-supplemented (Control), supplementation with coconut oil at 50 g/kg (CO5), supplementation with mangosteen peel at 30 g/kg (MP3) and supplementation with CO5 and MP3 (COM), of total DM intake. Animals received concentrate at 10 g/kg of BW, and rice straw was given ad libitum. Abundance of total bacteria was increased by CO5 supplementation, whereas populations of protozoa and Fibrobacter succinogenes were reduced by CO5 and COM supplementation. Dietary supplementation did not affect methanogen, Ruminococcus flavefaciens or Ruminococcus albus abundances. Dietary treatments changed denaturing gradient gel electrophoresis (DGGE) band patterns of methanogens and protozoa when compared with the control group, especially when supplemented with MP3. Supplementation of COM resulted in the greatest difference in pattern of DGGE bands for total bacteria compared with the control. Coconut oil and mangosteen peel supplementation resulted in changing of rumen microbial abundances and communities; however, combination of them could be more benefit to improve rumen fermentation of swamp buffalo fed on rice straw.

  17. Bacteria isolated from amoebae/bacteria consortium

    Science.gov (United States)

    Tyndall, Richard L.

    1995-01-01

    New protozoan derived microbial consortia and method for their isolation are provided. Consortia and bacteria isolated therefrom are useful for treating wastes such as trichloroethylene and trinitrotoluene. Consortia, bacteria isolated therefrom, and dispersants isolated therefrom are useful for dispersing hydrocarbons such as oil, creosote, wax, and grease.

  18. Influence of topsoil of pyroclastic origin on microbial contamination of groundwater in fractured carbonate aquifers

    Science.gov (United States)

    Naclerio, Gino; Petrella, Emma; Nerone, Valentina; Allocca, Vincenzo; de Vita, Pantaleone; Celico, Fulvio

    2008-09-01

    The aim of the research was to analyse the influence of a topsoil of pyroclastic origin on microbial contamination of groundwater in a carbonate aquifer and verify the reliability of thermotolerant coliforms and fecal enterococci as bacterial indicators. The research was carried out through hydrogeological and microbiological monitoring at an experimental field site in Italy during two hydrologic years and through column tests in a laboratory. The taxonomic classification of fecal indicators detected in spring water samples was performed using API20 galleries. Fecal enterococci were also identified by means of 16S rRNA gene sequencing. The topsoil of pyroclastic origin significantly retains both thermotolerant coliforms and fecal enterococci. Results of column tests carried out in soil blocks collected randomly within the test site suggest that Escherichia coli was more retained than Enterococcus faecalis, even though this difference is statistically significant in only two out of six soil samples. Thus, a non-uniform difference in retention is expected at field scale. This suggestion is in agreement with the results of the microbiological monitoring. In fact, fecal enterococci were a more reliable indicator than thermotolerant coliforms for detecting contamination at both seasonal springs of the aquifer system, while no significant differences were observed at the perennial spring.

  19. Development of the chick microbiome: How early exposure influences future microbial diversity

    Directory of Open Access Journals (Sweden)

    Anne L Ballou

    2016-01-01

    Full Text Available The concept of improving animal health through improved gut health has existed in food animal production for decades; however, only recently have we had the tools to identify microbes in the intestine associated with improved performance. Currently, little is known about how the avian microbiome develops or the factors that affect its composition. To begin to address this knowledge gap, the present study assessed the development of the cecal microbiome in chicks from hatch to 28 days of age with and without a live Salmonella vaccine and/or probiotic supplement; both are products intended to promote gut health. The microbiome of growing chicks develops rapidly from days 1-3, and the microbiome is primarily Enterobacteriaceae, but Firmicutes increase in abundance and taxonomic diversity starting around day 7. As the microbiome continues to develop, the influence of the treatments becomes stronger. Predicted metagenomic content suggests that functionally, treatment may stimulate more differences at day 14, despite the strong taxonomic differences at day 28. These results demonstrate that these live microbial treatments do impact the development of the bacterial taxa found in the growing chicks; however, additional experiments are needed to understand the biochemical and functional consequences of these alterations.

  20. Influence of bovine lactoferrin on the growth of selected probiotic bacteria under aerobic conditions.

    Science.gov (United States)

    Chen, Po-Wen; Ku, Yu-We; Chu, Fang-Yi

    2014-10-01

    Bovine lactoferrin (bLf) is a natural glycoprotein, and it shows broad-spectrum antimicrobial activity. However, reports on the influences of bLf on probiotic bacteria have been mixed. We examined the effects of apo-bLf (between 0.25 and 128 mg/mL) on both aerobic and anaerobic cultures of probiotics. We found that bLf had similar effects on the growth of probiotics under aerobic or anaerobic conditions, and that it actively and significantly (at concentrations of >0.25 mg/mL) retarded the growth rate of Bifidobacterium bifidum (ATCC 29521), B. longum (ATCC 15707), B. lactis (BCRC 17394), B. infantis (ATCC 15697), Lactobacillus reuteri (ATCC 23272), L. rhamnosus (ATCC 53103), and L. coryniformis (ATCC 25602) in a dose-dependent manner. Otherwise, minimal inhibitory concentrations (MICs) were 128 or >128 mg/mL against B. bifidum, B. longum, B. lactis, L. reuteri, and L. rhamnosus (ATCC 53103). With regard to MICs, bLf showed at least four-fold lower inhibitory effect on probiotics than on pathogens. Intriguingly, bLf (>0.25 mg/mL) significantly enhanced the growth of Rhamnosus (ATCC 7469) and L. acidophilus (BCRC 14065) by approximately 40-200 %, during their late periods of growth. Supernatants produced from aerobic but not anaerobic cultures of L. acidophilus reduced the growth of Escherichia coli by about 20 %. Thus, bLf displayed a dose-dependent inhibitory effect on the growth of most probiotic strains under either aerobic or anaerobic conditions. An antibacterial supernatant prepared from the aerobic cultures may have significant practical use. PMID:24916115

  1. Influence of forage phenolics on ruminal fibrolytic bacteria and in vitro fiber degradation.

    Science.gov (United States)

    Varel, V H; Jung, H J

    1986-08-01

    In vitro cultures of ruminal microorganisms were used to determine the effect of cinnamic acid and vanillin on the digestibility of cellulose and xylan. Cinnamic acid and vanillin depressed in vitro dry matter disappearance of cellulose 14 and 49%, respectively, when rumen fluid was the inoculum. The number of viable Bacteroides succinogenes cells, the predominant cellulolytic organism, was threefold higher for fermentations which contained vanillin than for control fermentations. When xylan replaced cellulose as the substrate, a 14% decrease in the digestibility of xylan was observed with vanillin added; however, the number of viable xylanolytic bacteria cultured from the batch fermentation was 10-fold greater than that of control fermentations. The doubling time of B. succinogenes was increased from 2.32 to 2.58 h when vanillin was added to cellobiose medium, and absorbance was one-half that of controls after 18 h. The growth rate of Ruminococcus albus and Ruminococcus flavefaciens was inhibited more by p-coumaric acid than by vanillin, although no reduction of final absorbance was observed in their growth cycles. Vanillin, and to a lesser extent cinnamic acid, appeared to prevent the attachment of B. succinogenes cells to cellulose particles, but did not affect dissociation of cells from the particles. B. succinogenes, R. albus, R. flavefaciens, and Butyrivibrio fibrisolvens all modified the parent monomers cinnamic acid, p-coumaric acid, ferulic acid, and vanillin, with B. fibrisolvens causing the most extensive modification. These results suggest that phenolic monomers can inhibit digestibility of cellulose and xylan, possibly by influencing attachment of the fibrolytic microorganisms to fiber particles. The reduced bacterial attachment to structural carbohydrates in the presence of vanillin may generate more free-floating fibrolytic organisms, thus giving a deceptively higher viable count.

  2. Characterizing relationships among fecal indicator bacteria, microbial source tracking markers, and associated waterborne pathogen occurrence in stream water and sediments in a mixed land use watershed.

    Science.gov (United States)

    Bradshaw, J Kenneth; Snyder, Blake J; Oladeinde, Adelumola; Spidle, David; Berrang, Mark E; Meinersmann, Richard J; Oakley, Brian; Sidle, Roy C; Sullivan, Kathleen; Molina, Marirosa

    2016-09-15

    Bed sediments of streams and rivers may store high concentrations of fecal indicator bacteria (FIB) and pathogens. Due to resuspension events, these contaminants can be mobilized into the water column and affect overall water quality. Other bacterial indicators such as microbial source tracking (MST) markers, developed to determine potential sources of fecal contamination, can also be resuspended from bed sediments. The primary objective of this study was to predict occurrence of waterborne pathogens in water and streambed sediments using a simple statistical model that includes traditionally measured FIB, environmental parameters and source allocation, using MST markers as predictor variables. Synoptic sampling events were conducted during baseflow conditions downstream from agricultural (AG), forested (FORS), and wastewater pollution control plant (WPCP) land uses. Concentrations of FIB and MST markers were measured in water and sediments, along with occurrences of the enteric pathogens Campylobacter, Listeria and Salmonella, and the virulence gene that carries Shiga toxin, stx2. Pathogens were detected in water more often than in underlying sediments. Shiga toxin was significantly related to land use, with concentrations of the ruminant marker selected as an independent variable that could correctly classify 76% and 64% of observed Shiga toxin occurrences in water and sediment, respectively. FIB concentrations and water quality parameters were also selected as independent variables that correctly classified Shiga toxin occurrences in water and sediment (54%-87%), and Salmonella occurrences in water (96%). Relationships between pathogens and indicator variables were generally inconsistent and no single indicator adequately described occurrence of all pathogens. Because of inconsistent relationships between individual pathogens and FIB/MST markers, incorporating a combination of FIB, water quality measurements, and MST markers may be the best way to assess

  3. Influence of autochthonous lactic acid bacteria on the proteolysis, microstructure and sensory properties of low fat UF cheeses during ripening

    Directory of Open Access Journals (Sweden)

    Dragana Pesic Mikulec

    2012-06-01

    Full Text Available The influence of commercial bacteria Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris (cheese A and combinations of autochthonous lactic acid bacteria (LAB strains Lactobacillus paracasei ssp. paracasei 08, Lactococcus lactis ssp. cremoris 656, Lactococcus lactis ssp. lactis 653 (cheese B and C on composition, proteolysis, microstructure and sensory properties of low fat cheeses during ripening was investigated. Low fat cast ultra-filtered (UF cheeses were produced according to the defined production procedure by mixing UF milk protein powder, skim milk and cream. Significant influence of different LAB strains on composition, primary proteolysis and microstructure was not found. Cheeses made with autochthonous LAB showed a higher rate of secondary proteolysis, as well as higher flavour scores, and were more acceptable than control cheese.

  4. Environmental transcriptome analysis reveals physiological differences between biofilm and planktonic modes of life of the iron oxidizing bacteria Leptospirillum spp. in their natural microbial community

    Directory of Open Access Journals (Sweden)

    Parro Víctor

    2010-06-01

    Full Text Available Abstract Background Extreme acidic environments are characterized by their high metal content and lack of nutrients (oligotrophy. Macroscopic biofilms and filaments usually grow on the water-air interface or under the stream attached to solid substrates (streamers. In the Río Tinto (Spain, brown filaments develop under the water stream where the Gram-negative iron-oxidizing bacteria Leptospirillum spp. (L. ferrooxidans and L. ferriphilum and Acidithiobacillus ferrooxidans are abundant. These microorganisms play a critical role in bioleaching processes for industrial (biominery and environmental applications (acid mine drainage, bioremediation. The aim of this study was to investigate the physiological differences between the free living (planktonic and the sessile (biofilm associated lifestyles of Leptospirillum spp. as part of its natural extremely acidophilic community. Results Total RNA extracted from environmental samples was used to determine the composition of the metabolically active members of the microbial community and then to compare the biofilm and planktonic environmental transcriptomes by hybridizing to a genomic microarray of L. ferrooxidans. Genes up-regulated in the filamentous biofilm are involved in cellular functions related to biofilm formation and maintenance, such as: motility and quorum sensing (mqsR, cheAY, fliA, motAB, synthesis of cell wall structures (lnt, murA, murB, specific proteases (clpX/clpP, stress response chaperons (clpB, clpC, grpE-dnaKJ, groESL, etc. Additionally, genes involved in mixed acid fermentation (poxB, ackA were up-regulated in the biofilm. This result, together with the presence of small organic acids like acetate and formate (1.36 mM and 0.06 mM respectively in the acidic (pH 1.8 water stream, suggests that either L. ferrooxidans or other member of the microbial community are producing acetate in the acidophilic biofilm under microaerophilic conditions. Conclusions Our results indicate that the

  5. Influence of ionic strength and substratum hydrophobicity on the co-adhesion of oral microbial pairs

    NARCIS (Netherlands)

    vanderMei, HC; Busscher, HJ; Bos, R.R.M.

    1996-01-01

    Co-adhesion between oral microbial pairs (i.e. adhesion of a planktonic micro-organism, University of organism to a sessile organism adhering to a substratum surface) has been described as a highly specific interaction, mediated by stereochemical groups on the interacting microbial cell surfaces, an

  6. Microbial Fouling Characteristics of Slime-forming Bacteria on Composite Coating of Ni-P-PTFE%Ni-P-PTFE镀层表面黏液形成菌的污垢特性

    Institute of Scientific and Technical Information of China (English)

    徐志明; 姚响; 白文玉; 刘坐东; 王景涛

    2016-01-01

    目的 研究Ni-P-PTFE镀层改性换热面对微生物污垢的抑制作用.方法 调整化学镀工艺,在换热器常用的低碳钢表面制备不同性能的复合镀层,获取镀层厚度、镀速和表面能等参数.对低碳钢和Ni-P-PTFE复合镀层进行微观形貌对比,并进行黏液形成菌污垢静置实验,测量菌悬液中的细菌数量变化及试样质量变化.分析复合镀层表面在黏液形成菌污垢实验前后的宏观和微观形貌,与低碳钢试样进行对比,研究复合镀层试样表面能和镀层表面污垢沉积的关联性.结果 Ni-P-PTFE复合镀层改变了换热面的表面性能,接触角明显增大,表面能由改性前的49.16 mJ/m2降低到7.54 mJ/m2.与低碳钢的静置结果 相比,悬挂复合镀层试样的菌悬液中黏液形成菌数量显著减少,复合镀层试样表面平均污垢沉积量减少到2.3 g/m2(低碳钢表面为12.1 g/m2).结论 Ni-P-PTFE镀层可以有效抑制黏液形成菌的生长,低表面能有效减少了微生物污垢的沉积,使其表现出良好的耐蚀性和抗垢性.%Objective In order to investigate the influence of the modified surface on microbial fouling, the microbial fouling ex-periment of slime-forming bacteria on the composite coating of Ni-P-PTFE was conducted in this study. Methods Several composite coatings with different properties were prepared by electroless plating on the surface of carbon steel and the parameters such as plat-ing thickness, plating speed and surface energy were obtained. The microstructure of electroless composite plating of Ni-P-PTFE and low carbon was compared by scanning electron microscopy, and the slime-forming bacteria microbial fouling experiments of low carbon steel and the composite coatings samples were conducted. The variation of bacteria amount in the bacterial suspension and weight variation of the samples were documented; The macroscopic and microscopic morphologies of the composite coatings were obtained and analyzed

  7. Microbial growth with vapor-phase substrate

    Energy Technology Data Exchange (ETDEWEB)

    Hanzel, Joanna; Thullner, Martin; Harms, Hauke [UFZ - Helmholtz Centre for Environmental Research, Department of Environmental Microbiology, Permoserstrasse 15, 04318 Leipzig (Germany); Wick, Lukas Y., E-mail: lukas.wick@ufz.de [UFZ - Helmholtz Centre for Environmental Research, Department of Environmental Microbiology, Permoserstrasse 15, 04318 Leipzig (Germany)

    2011-04-15

    Limited information exists on influences of the diffusive transport of volatile organic contaminants (VOC) on bacterial activity in the unsaturated zone of the terrestrial subsurface. Diffusion of VOC in the vapor-phase is much more efficient than in water and results in effective VOC transport and high bioavailability despite restricted mobility of bacteria in the vadose zone. Since many bacteria tend to accumulate at solid-water, solid-air and air-water interfaces, such phase boundaries are of a special interest for VOC-biodegradation. In an attempt to evaluate microbial activity toward air-borne substrates, this study investigated the spatio-temporal interplay between growth of Pseudomonas putida (NAH7) on vapor-phase naphthalene (NAPH) and its repercussion on vapor-phase NAPH concentrations. Our data demonstrate that growth rates of strain PpG7 were inversely correlated to the distance from the source of vapor-phase NAPH. Despite the high gas phase diffusivity of NAPH, microbial growth was absent at distances above 5 cm from the source when sufficient biomass was located in between. This indicates a high efficiency of suspended bacteria to acquire vapor-phase compounds and influence headspace concentration gradients at the centimeter-scale. It further suggests a crucial role of microorganisms as biofilters for gas-phase VOC emanating from contaminated groundwater or soil. - Research highlights: > Suspended bacteria have a high efficiency to degrade vapor-phase naphthalene. > Bacteria influence NAPH vapor-phase concentration gradients at centimeter-scale. > Microbial growth on vapor-phase naphthalene is inversely correlated to its source. > Bacteria are good biofilters for gas-phase NAPH emanating from contaminated sites. - Suspended bacteria have a high efficiency to degrade vapor-phase naphthalene and effectively influence vapor-phase naphthalene concentration gradients at the centimeter scale.

  8. Microbial Biofilms in Endodontic Infections: An Update Review

    OpenAIRE

    Zahed Mohammadi; Flavio Palazzi; Luciano Giardino; Sousan Shalavi

    2013-01-01

    Biofilms and microbial aggregates are the common mechanisms for the survival of bacteria in nature. In other words, the ability to form biofilms has been regarded as a virulence factor. Microbial biofilms play an essential role in several infectious diseases such as pulp and periradicular pathosis. The aim of this article was to review the adaptation mechanisms of biofilms, their roles in pulpal and periapical pathosis, factors influencing biofilm formation, mechanisms of their antimicrobial ...

  9. Arctic microbial and next-generation sequencing approach for bacteria in snow and frost flowers: selected identification, abundance and freezing nucleation

    Science.gov (United States)

    Mortazavi, R.; Attiya, S.; Ariya, P. A.

    2015-06-01

    During the spring of 2009, as part of the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) campaign in Barrow, Alaska, USA, we examined the identity, population diversity, freezing nucleation ability of the microbial communities of five different snow types and frost flowers. In addition to the culturing and gene-sequence-based identification approach, we utilized a state-of-the-art genomic next-generation sequencing (NGS) technique to examine the diversity of bacterial communities in Arctic samples. Known phyla or candidate divisions were detected (11-18) with the majority of sequences (12.3-83.1%) belonging to one of the five major phyla: Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Cyanobacteria. The number of genera detected ranged from, 101-245. The highest number of cultivable bacteria was observed in frost flowers (FFs) and accumulated snow (AS) with 325 ± 35 and 314 ± 142 CFU m L-1, respectively; and for cultivable fungi 5 ± 1 CFU m L-1 in windpack (WP) and blowing snow (BS). Morphology/elemental composition and ice-nucleating abilities of the identified taxa were obtained using high resolution electron microscopy with energy-dispersive X-ray spectroscopy and ice nucleation cold-plate, respectively. Freezing point temperatures for bacterial isolates ranged from -20.3 ± 1.5 to -15.7 ± 5.6 °C, and for melted snow samples from -9.5 ± 1.0 to -18.4 ± 0.1 °C. An isolate belonging to the genus Bacillus (96% similarity) had ice nucleation activity of -6.8 ± 0.2 °C. Comparison with Montreal urban snow, revealed that a seemingly diverse community of bacteria exists in the Arctic with some taxa possibly originating from distinct ecological environments. We discuss the potential impact of snow microorganisms in the freezing and melting process of the snowpack in the Arctic.

  10. Microbial extracellular electron transfer and its relevance to iron corrosion.

    Science.gov (United States)

    Kato, Souichiro

    2016-03-01

    Extracellular electron transfer (EET) is a microbial metabolism that enables efficient electron transfer between microbial cells and extracellular solid materials. Microorganisms harbouring EET abilities have received considerable attention for their various biotechnological applications, including bioleaching and bioelectrochemical systems. On the other hand, recent research revealed that microbial EET potentially induces corrosion of iron structures. It has been well known that corrosion of iron occurring under anoxic conditions is mostly caused by microbial activities, which is termed as microbiologically influenced corrosion (MIC). Among diverse MIC mechanisms, microbial EET activity that enhances corrosion via direct uptake of electrons from metallic iron, specifically termed as electrical MIC (EMIC), has been regarded as one of the major causative factors. The EMIC-inducing microorganisms initially identified were certain sulfate-reducing bacteria and methanogenic archaea isolated from marine environments. Subsequently, abilities to induce EMIC were also demonstrated in diverse anaerobic microorganisms in freshwater environments and oil fields, including acetogenic bacteria and nitrate-reducing bacteria. Abilities of EET and EMIC are now regarded as microbial traits more widespread among diverse microbial clades than was thought previously. In this review, basic understandings of microbial EET and recent progresses in the EMIC research are introduced. PMID:26863985

  11. Trophic interactions between rhizosphere bacteria and bacterial feeders influenced by phosphate and aphids in barley

    DEFF Research Database (Denmark)

    Strandmark, Lisa Bjørnlund; Mørk, Søren; Madsen, Mette Vestergård;

    2006-01-01

    -proteobacteria increased with P addition. To evaluate if differences in bacteria in terms of their quality as food could partly explain the observed differences in protozoan and nematode abundances, growth of the flagellate Cercomonas sp. was assessed with 935 bacteria isolated from the different treatments. This assay......The aim was to study the effects of P fertilization and leaf aphid attack on the trophic interactions of bacteria and bacterial feeders in the rhizospheres of barley plants. The density of protozoa peaked in the rhizospheres of plants fertilized with N and P, whereas nematodes peaked...... indicated that bacterial isolates were of higher food quality to Cercomonas sp. in NP than in N rhizospheres when plants were subjected to aphid attack. Bacteria of high and low food quality for Cercomonas sp., respectively, were fed to the nematode Caenorhabditis elegans and larval production examined. a...

  12. Carbohydrate-degrading bacteria closely associated with Tetraselmis indica: Influence on algal growth

    Digital Repository Service at National Institute of Oceanography (India)

    Arora, M.; Anil, A.C.; Delany, J.; Rajarajan, N.; Emami, K.; Mesbahi, E.

    The interactions between the algal species Tetraselmis indica and strains of bacteria are examined. Three bacterial strains were isolated and sequence analysis of the 16S rDNA indicated that the organisms belong to the genera Pseudomonas...

  13. The influence of surface treatment on hydrophobicity, protein adsorption and microbial colonisation of silicone hydrogel contact lenses

    OpenAIRE

    Santos, Lívia; Rodrigues, Diana Alexandra Ferreira; Lira, Madalena; Oliveira, M. Elisabete; Oliveira, Rosário; Yebra-Pimentel Vilar, Eva; Azeredo, Joana

    2007-01-01

    Purpose: To evaluate the influence of surface treatment of silicone-hydrogel CL on lens hydrophobicity, protein adsorption and microbial colonisation by studying several silicone hydrogel contact lenses (CL) with and without surface treatment. The lenses used in this study were Balafilcon A, Lotrafilcon A, Lotrafilcon B and Galyfilcon A. A conventional hydrogel CL (Etafilcon A) was also tested. Methods: Hydrophobicity was determined through contact angle measurement using the advancing typ...

  14. Influence of DNA extraction on oral microbial profiles obtained via 16S rRNA gene sequencing

    OpenAIRE

    Diaz, Patricia I.; Abusleme, Loreto; Hong, Bo-Young; Amanda K. Dupuy; Linda D Strausbaugh

    2014-01-01

    Background and objective: The advent of next-generation sequencing has significantly facilitated characterization of the oral microbiome. Despite great efforts in streamlining the processes of sequencing and data curation, upstream steps required for amplicon library generation could still influence 16S rRNA gene-based microbial profiles. Among upstream processes, DNA extraction is a critical step that could represent a great source of bias. Accounting for bias introduced by extraction proced...

  15. Influence of cereal non-starch polysaccharides on ileo-caecal and rectal microbial populations in growing pigs

    DEFF Research Database (Denmark)

    Høgberg, Ann; Lindberg, Jan; Leser, Thomas;

    2004-01-01

    The effect of cereal non-starch polysaccharides (NSP) on the gut microbial populations was studied in 5 growing pigs between 39-116 kg body weight according to a Latin square design. The diets were composed to contain different NSP levels. The control diet had a normal NSP content (139 g/kg dry m......, respectively. Both the total gut microflora and the coliform flora were influenced by the dietary NSP content....

  16. Influence of Environmental Stressors on the Physiology of Pollutant Degrading Bacteria

    DEFF Research Database (Denmark)

    Svenningsen, Nanna Bygvraa

    compounds. However, soil environments frequently undergo changes, for instance in nutrient and water availability, and microbial cells residing in soils are continuously exposed to various abiotic and biotic insults. Thriving in soil is therefore difficult and conditions are rarely optimal for the microbial...... microorganisms, that being indigenous populations already present in a given environment or specific microorganisms delivered to the environment for bioremediation purposes, a deeper understanding of the abovementioned characteristics is needed. This PhD project aimed at studying the physiological responses...

  17. A genome probe survey of the microbial community in oil fields

    Energy Technology Data Exchange (ETDEWEB)

    Voordouw, G.; Telang, A. [Calgary Univ., AB (Canada). Dept. of Biology

    2000-07-01

    Reverse sample genome probing (RSGP) was conducted in water injected oil fields in Western Canada in order to analyze the microbial community in the fields to identify different bacteria responsible for microbially influenced corrosion (MIC) or souring. Oil fields of moderate temperature and salinity have an anaerobic microbial community consisting of sulfate-reducing bacteria (SRB), sulfide-oxidizing bacteria (SOB) and heterotrophic bacteria. The RSGP revealed that selected SRB are enhanced at metal surfaces and can therefore contribute to corrosion. Some of the SRB were found to be insensitive to biocides that are used in the field. RSGP also showed that injection of nitrate, instead of sulfate, leads to a marked increase of Campylobacter sp., which gets its energy from the oxidation of sulfide by nitrate. It was concluded that RSGP is a useful tool to monitor the effects of chemical stresses on the oil field microbial community. 13 refs., 2 figs.

  18. Anaerobic thermophilic bacteria isolated from a Venezuelan oil field and its potential use in microbial improved oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Trebbau, G.; Fernandez, B.; Marin, A. [INTEVEP S.A., Caracas (Venezuela)

    1995-12-31

    The objective of this work is to determine the ability of indigenous bacteria from a Venezuelan oil field to grow under reservoir conditions inside a porous media, and to produce metabolites capable of recovering residual crude oil. For this purpose, samples of formation waters from a central-eastern Venezuelan oil reservoir were enriched with different carbon sources and a mineral basal media. Formation water was used as a source of trace metals. The enrichments obtained were incubated at reservoir temperature (71{degrees}C), reservoir pressure (1,200 psi), and under anaerobic conditions for both outside and inside porous media (Berea core). Growth and metabolic activity was followed outside porous media by measuring absorbance at 660 nm, increases in pressure, and decreases in pH. Inside porous media bacterial activity was determined by visual examination of the produced waters (gas bubbles and bacterial cells). All the carbohydrates tested outside porous media showed good growth at reservoir conditions. The pH was lowered, gases such as CO{sub 2} and CH{sub 4} were identified by GC. Surface tension was lowered in some enrichments by 30% when compared to controls. Growth was decreased inside porous media, but gases were produced and helped displace oil. In addition, 10% residual oil was recovered from the Berea core. Mathematical modeling was applied to the laboratory coreflood experiment to evaluate the reproducibility of the results obtained.

  19. PANI-Ag-Cu Nanocomposite Thin Films Based Impedimetric Microbial Sensor for Detection of E. coli Bacteria

    Directory of Open Access Journals (Sweden)

    Huda Abdullah

    2014-01-01

    Full Text Available PANI-Ag-Cu nanocomposite thin films were prepared by sol-gel method and deposited on the glass substrate using spin coating technique. Polyaniline was synthesized by chemical oxidative polymerization of aniline monomer in the presence of nitric acid. The films were characterized using XRD, FTIR, and UV-Visible spectroscopy. The performance of the sensor was conducted using electrochemical impedance spectroscopy to obtain the change in impedance of the sensor film before and after incubation with E. coli bacteria in water. The peaks in XRD pattern confirm the presence of Ag and Cu nanoparticles in face-centered cubic structure. FTIR analysis shows the stretching of N–H in the polyaniline structure. The absorption band from UV-Visible spectroscopy shows high peaks between 400 nm and 500 nm which indicate the presence of Ag and Cu nanoparticles, respectively. Impedance analysis indicates that the change in impedance of the films decreases with the presence of E. coli. The sensitivity on E. coli increases for the sample with high concentration of Cu.

  20. Protection of beryllium metal against microbial influenced corrosion using silane self-assembled monolayers

    Science.gov (United States)

    Vaidya, Rajendra U.; Deshpande, Alina; Hersman, Larry; Brozik, Susan M.; Butt, Darryl

    1999-08-01

    The effectiveness of a self-assembled silane monolayer as protection for beryllium against microbiologically influenced corrosion (MIC) was demonstrated. Four-point bend tests on coated and uncoated beryllium samples were conducted after microbiological exposures, and the effectiveness of these coatings as MIC protection was reported through mechanical property evaluations. Application of the silane monolayer to the beryllium surfaces was found to prevent degradation of the failure strength and displacement-to-failure of beryllium in bending. In contrast, the uncoated beryllium samples exhibited a severe reduction in these mechanical properties in the presence of the marine Pseudomonas bacteria. The potentiodynamic measurements showed that both the uncoated and coated samples pitted at the open-circuit potential. However, the size and distribution of the corrosion pits formed on the surface of the beryllium samples were significantly different for the various cases (coated vs uncoated samples exposed to control vs inoculated medium). This study demonstrates the following: (1) the deleterious effects of MIC on the mechanical properties of beryllium and (2) the potential for developing fast, easy, and cost-effective MIC protection for beryllium metal using silane self-assemblies.

  1. An investigation of microbial diversity in crude oil & seawater injection systems and microbiologically influenced corrosion (MIC) of linepipe steels under different exposure conditions

    Science.gov (United States)

    AlAbbas, Faisal Mohammed

    During oil and gas operations, pipeline networks are subjected to different corrosion deterioration mechanisms that result from the interaction between the fluid process and the linepipe steel. Among these mechanisms is microbiologically influenced corrosion (MIC) that results from accelerated deterioration caused by different indigenous microorganisms that naturally reside in the hydrocarbon and associated seawater injection systems. The focus of this research is to obtain comprehensive understanding of MIC. This work has explored the most essential elements (identifications, implications and mitigations) required to fully understand MIC. Advanced molecular-based techniques, including sequencing of 16S rRNA genes via 454 pyrosequencing methodologies, were deployed to provide in-depth understanding of the microbial diversity associated with crude oil and seawater injection systems and their relevant impact on MIC. Key microbes including sulfate reducing bacteria (SRB) and iron reducing bacteria (IRB) were cultivated from sour oil well field samples. The microbes' phylotypes were identified in the laboratory to gain more thorough understanding of how they impact microbial corrosion. Electrochemical and advanced surface analytical techniques were used for corrosion evaluations of linepipe carbon steels (API 5L X52 and X80) under different exposure conditions. On the identification front, 454 pyrosequencing of both 16S rRNA genes indicated that the microbial communities in the corrosion products obtained from the sour oil pipeline, sweet crude pipeline and seawater pipeline were dominated by bacteria, though archaeal sequences (predominately Methanobacteriaceae and Methanomicrobiaceae) were also identified in the sweet and sour crude oil samples, respectively. The dominant bacterial phylotypes in the sour crude sample included members of the Thermoanaerobacterales, Synergistales, and Syntrophobacterales. In the sweet crude sample, the dominant phylotypes included

  2. Bioelectricity generation in microbial fuel cell using natural microflora and isolated pure culture bacteria from anaerobic palm oil mill effluent sludge.

    Science.gov (United States)

    Nor, Muhamad Hanif Md; Mubarak, Mohd Fahmi Muhammad; Elmi, Hassan Sh Abdirahman; Ibrahim, Norahim; Wahab, Mohd Firdaus Abdul; Ibrahim, Zaharah

    2015-08-01

    A double-chambered membrane microbial fuel cell (MFC) was constructed to investigate the potential use of natural microflora anaerobic palm oil mill effluent (POME) sludge and pure culture bacteria isolated from anaerobic POME sludge as inoculum for electricity generation. Sterilized final discharge POME was used as the substrate with no addition of nutrients. MFC operation using natural microflora anaerobic POME sludge showed a maximum power density and current density of 85.11mW/m(2) and 91.12mA/m(2) respectively. Bacterial identification using 16S rRNA analysis of the pure culture isolated from the biofilm on the anode MFC was identified as Pseudomonas aeruginosa strain ZH1. The electricity generated in MFC using P. aeruginosa strain ZH1 showed maximum power density and current density of 451.26mW/m(2) and 654.90mA/m(2) respectively which were five times higher in power density and seven times higher in current density compared to that of MFC using anaerobic POME sludge.

  3. Assessment of the effects of microbially influenced degradation on a massive concrete structure. Final report, Report 5

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, R.D. [Biodegradation Systems, Inc., Idaho Falls, ID (United States)

    1995-07-08

    There is a need to estimate the effect of environmental conditions on construction materials to be used in the repository at Yucca Mountain. Previous reports from this project have demonstrated that it is important to develop an understanding of microbially influenced degradation (MID) development and its influence on massive concrete structures. Further, it has been shown that the most effective way to obtain quantitative data on the effects of MID on the structural integrity of repository concrete is to study manmade, analog structures known to be susceptible to MID. The cooling tower shell located at the Ohaaki Power Station near Wairakei, New Zealand is such a structure.

  4. Assessment of the effects of microbially influenced degradation on a massive concrete structure. Final report, Report 5

    International Nuclear Information System (INIS)

    There is a need to estimate the effect of environmental conditions on construction materials to be used in the repository at Yucca Mountain. Previous reports from this project have demonstrated that it is important to develop an understanding of microbially influenced degradation (MID) development and its influence on massive concrete structures. Further, it has been shown that the most effective way to obtain quantitative data on the effects of MID on the structural integrity of repository concrete is to study manmade, analog structures known to be susceptible to MID. The cooling tower shell located at the Ohaaki Power Station near Wairakei, New Zealand is such a structure

  5. Soil pH, total phosphorus, climate and distance are the major factors influencing microbial activity at a regional spatial scale

    DEFF Research Database (Denmark)

    Cao, Haichuan; Chen, Ruirui; Wang, Libing;

    2016-01-01

    scaling clearly revealed that soil microbial activities showed distinct differentiation at different sites over a regional spatial scale, which were strongly affected by soil pH, total P, rainfall, temperature, soil type and location. In addition, microbial community structure was greatly influenced...... scales. There are common (distance, climate, pH and soil type) but differentiated aspects (TP, SOC and N) in the biogeography of soil microbial community structure and activity.......Considering the extensive functional redundancy in microbial communities and great difficulty in elucidating it based on taxonomic structure, studies on the biogeography of soil microbial activity at large spatial scale are as important as microbial community structure. Eighty-four soil samples...

  6. Influence of Sulfate-Reducing Bacteria on the Corrosion Residual Strength of an AZ91D Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Xianyong Zhu

    2014-10-01

    Full Text Available In this paper, the corrosion residual strength of the AZ91D magnesium alloy in the presence of sulfate-reducing bacteria is studied. In the experiments, the chemical composition of corrosion film was analyzed by a scanning electron microscope with energy dispersive X-ray spectroscopy. In addition, a series of instruments, such as scanning electronic microscope, pH-meter and an AG-10TA materials test machine, were applied to test and record the morphology of the corrosion product, fracture texture and mechanical properties of the AZ91D magnesium alloy. The experiments show that the sulfate-reducing bacteria (SRB play an important role in the corrosion process of the AZ91D magnesium alloy. Pitting corrosion was enhanced by sulfate-reducing bacteria. Corrosion pits are important defects that could lead to a significant stress concentration in the tensile process. As a result, sulfate-reducing bacteria influence the corrosion residual strength of the AZ91D magnesium alloy by accelerating pitting corrosion.

  7. Electrochemical noise measurements of sustained microbially influenced pitting corrosion in a laboratory flow loop system

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.; Frank, J.R.; St. Martin, E.J. [Argonne National Lab., IL (United States); Pope, D.H. [Bioindustrial Technologies, Inc., Georgetown, TX (United States)

    1999-11-01

    Because of the chaotic nature of the corrosion process and the complexity of the electrochemical noise signals that are generated, there is no generally accepted method of measuring and interpreting these signals that allows the consistent detection and identification of sustained localized pitting (SLP) as compared to general corrosion. The authors have reexamined electrochemical noise analysis (ENA) of localized corrosion using different hardware, signal collection, and signal processing designs than those used in conventional ENA techniques. The new data acquisition system was designed to identify and monitor the progress of SLP by analyzing the power spectral density (PSD) of the trend of the corrosion current noise level (CNL) and potential noise level (PNL). Each CNL and PNL data point was calculated from the root-mean-square value of the ac components of current and potential fluctuation signals, which were measured simultaneously during a short time period. The PSD analysis results consistently demonstrated that the trends of PNL and CNL contain information that can be used to differentiate between SLP and general corrosion mechanisms. The degree of linear slope in the low-frequency portion of the PSD analysis was correlated with the SLP process. Laboratory metal coupons as well as commercial corrosion probes were tested to ensure the reproducibility and consistency of the results. The on-line monitoring capability of this new ENA method was evaluated in a bench-scale flow-loop system, which simulated microbially influenced corrosion (MIC) activity. The conditions in the test flow-loop system were controlled by the addition of microbes and different substrates to favor accelerated corrosion. The ENA results demonstrated that this in-situ corrosion monitoring system could effectively identify SLP corrosion associated with MIC, compared to a more uniform general corrosion mechanism. A reduction in SLP activity could be clearly detected by the ENA monitoring

  8. Electrochemical noise measurements of sustained microbially influenced pitting corrosion in a laboratory flow loop system.

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y. J.

    1999-01-13

    Because of the chaotic nature of the corrosion process and the complexity of the electrochemical noise signals that are generated, there is no generally accepted method of measuring and interpreting these signals that allows the consistent detection and identification of sustained localized pitting (SLP) as compared to general corrosion. We have reexamined electrochemical noise analysis (ENA) of localized corrosion using different hardware, signal collection, and signal processing designs than those used in conventional ENA techniques. The new data acquisition system was designed to identify and monitor the progress of SLP by analyzing the power spectral density (PSD) of the trend of the corrosion current noise level (CNL) and potential noise level (PNL). Each CNL and PNL data point was calculated from the root-mean- square value of the ac components of current and potential fluctuation signals, which were measured simultaneously during a short time period. The PSD analysis results consistently demonstrated that the trends of PNL and CNL contain information that can be used to differentiate between SLP and general corrosion mechanisms. The degree of linear slope in the low-frequency portion of the PSD analysis was correlated with the SLP process. Laboratory metal coupons as well as commercial corrosion probes were tested to ensure the reproducibility and consistency of the results. The on-line monitoring capability of this new ENA method was evaluated in a bench-scale flow-loop system, which simulated microbially influenced corrosion (MIC) activity. The conditions in the test flow-loop system were controlled by the addition of microbes and different substrates to favor accelerated corrosion. The ENA results demonstrated that this in-situ corrosion monitoring system could effectively identify SLP corrosion associated with MIC, compared to a more uniform general corrosion mechanism. A reduction in SLP activity could be clearly detected by the ENA monitoring system

  9. Green Rusts and Their Relationship to Iron Corrosion; a Key Role in Microbially Influenced Corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Genin, J.-M. R.; Refait, Ph.; Abdelmoula, M. [Universite Henri Poincare, Laboratoire de Chimie Physique et Microbiologie pour l' Environnement, UMR 7564, CNRS-Universite Henri Poincare-Nancy 1, Equipe Microbiologie et Physique and Departement Materiaux et Structures, ESSTIN (France)

    2002-03-15

    Moessbauer spectroscopy (MS) has often been used to characterise double-layered hydroxysalts usually named green rusts (GR) and to follow their Fe(II)/Fe(III) ratio during the oxidation process of Fe(OH){sub 2} in the presence of aggressive anions such as Cl{sup -}, SO{sub 4}{sup 2-}, CO{sub 3}{sup 2-},.... They are intermediate compounds between the initial metal Fe(0) via the Fe(II) and the final Fe(III) (oxyhydr)oxides constituting the usual rusts. E-pH Pourbaix diagrams of iron for predicting the aqueous corrosion conditions of iron-based materials are determined by monitoring the electrode potential E{sub h} and pH vs. time. The crystal structure of GRs, in any case constituted of layers of [Fe{sup II}{sub (1-x)}Fe{sup III}{sub x} (OH){sub 2}]{sup x+} that alternate with interlayers [(x/n)A{sup n-}.(mx/n)H{sub 2}O]{sup x-} made of A{sup n-} anions and water molecules, are presented. Several examples of the role of GRs are discussed, from chloride pitting of concrete reinforcing bars to bacterial corrosion of cast iron in water pipes or steel sheet piles in harbours. The efficiency of corrosion inhibitors like phosphate and their relationship to the oxidation of GRs are presented from basic MS studies. But most importantly, the evidence by MS of the dissimilatory reduction of a common ferric oxyhydroxide, {gamma}-FeOOH lepidocrocite, into a GR by the action of a bacterium, Shewanella putrefaciens, opens the path through which microbially influenced corrosion (MIC) operates. A cycling of aerobic and anaerobic conditions is necessary where GRs but also magnetite play likely the key role.

  10. Influence of microstructure on the microbial corrosión behaviour of stainless steels

    Directory of Open Access Journals (Sweden)

    Moreno, Diego Alejandro

    2000-08-01

    Full Text Available Several stainless steels (Types UNS S30300, S30400, S30403, S31600, S31603 and S42000 with different microstructural characteristics have been used to study the influence of heat treatments on microbiologically influenced corrosion (MIC. Biocorrosion and accelerated electrochemical testing was performed in various microbiological media. Two species of sulphate-reducing bacteria (SRB have been used in order to ascertain the influence of microstructure. The morphology of corrosion pits produced in both chloride and chloride plus sulphide -SRB metabolites- was inspected by optical and scanning electron microscopy (SEM complemented with energy-dispersive X-ray (EDX analysis. Results have shown different behaviours regarding corrosion resistance in each case studied. Sensitized austenitic stainless steels were more affected by the presence of aggressive anions and pitting potential (Ep values were more cathodic than those of as-received state. A corrosion enhancement is produced by the synergistic action of biogenic sulphides and chloride anions. Pitting corrosion in martensitic stainless Steel Type UNS S42000 was found in a- biocorrosion test. The pitting morphology is correlated to the chemical composition, the microstructure and the electrolyte.

    Se han utilizado aceros inoxidables de los tipos UNS S30300, S30400, S30403, S31600, S31603 y S42000, en diferentes estados microestructurales, para estudiar la influencia de los tratamientos térmicos sobre la corrosión microbiana. Para ello, se han realizado ensayos electroquímicos y ensayos de biocorrosión, en diferentes medios microbiológicos, utilizándose dos especies de bacterias reductoras de sulfatos (SRB. La morfología de las picaduras, producidas en presencia de cloruros y en presencia de cloruros más sulfuros -metabolitos de SRB-, se ha analizado por microscopía óptica y por microscopía electrónica de barrido (SEM complementada con análisis por energía dispersiva de rayos X

  11. Short-term incorporation of organic manures and biofertilizers influences biochemical and microbial characteristics of soils under an annual crop [Turmeric (Curcuma longa L.)].

    Science.gov (United States)

    Dinesh, R; Srinivasan, V; Hamza, S; Manjusha, A

    2010-06-01

    The study was conducted to determine whether short-term incorporation of organic manures and biofertilizers influence biochemical and microbial variables reflecting soil quality. For the study, soils were collected from a field experiment conducted on turmeric (Curcuma longa L.) involving organic nutrient management (ONM), chemical nutrient management (CNM) and integrated nutrient management (INM). The findings revealed that application of organic manures and biofertilizers (ONM and INM) positively influenced microbial biomass C, N mineralization, soil respiration and enzymes activities. Contrarily, greater metabolic quotient levels in CNM indicated a stressed soil microbial community. Principal component analysis indicated the strong relationship between microbial activity and the availability of labile and easily mineralizable organic matter. The findings imply that even short-term incorporation of organic manures and biofertilizers promoted soil microbial and enzyme activities and these parameters are sensitive enough to detect changes in soil quality due to short-term incorporation of biological fertilizers.

  12. Microbially influenced corrosion of stainless steel welds; Stainless ko yosetsubu no biseibutsu yuki fushoku no kisoteki kento

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Y.; Tomoto, K.; Okayama, C.; Matsuda, F. [Osaka University, Osaka (Japan). Joining and Welding Research Institute; Nishimura, M. [Mitsubishi Kakoki Kaisha Ltd., Tokyo (Japan); Sakane, T. [Institute for Fermentation, Osaka (Japan); Kaneko, Y. [Osaka University, Osaka (Japan). Faculty of Engineering

    1997-06-20

    This paper describes sensitivities of microbiologically influenced corrosion (MIC) for various stainless steels. The failure in the weld joint of SUS steel pipes occurred in about 60 days from the start-up of the sewage treatment plant. Any welding defects were not found, and the corrosion rate of welds was estimated to be 18 mm per year which was too fast. The corrosion was reproduced using the residual liquid from effluent treatment plant in laboratory. Corrosion pits and bacteria adhering around these were observed at the same time. For the experiments using boiled and sterilized waste water, corrosion did not occur. As a result, MIC was confirmed. Seven kinds of bacteria were separated and identified from the waste water. Among individual bacteria separated and incubated, Methylobacterium sp. and Arthrobacter sp. showed the most strong corrosion properties. It was estimated that these bacteria produced organic acid and its concentration became high locally at the site adhered by bacteria to generate the corrosion. The MIC was observed for several kinds of stainless steels used. There was not a significant difference in anti-corrosion due to the kind of steel. 19 refs., 10 figs., 4 tabs.

  13. 短芒大麦草青贮微生物特性研究及优良乳酸菌筛选%Microbial characteristics of Hordeum brevisubulatum silage and screening for lactic acid bacteria with high fermentation performance

    Institute of Scientific and Technical Information of China (English)

    陶雅; 李峰; 高凤芹; 孙启忠

    2015-01-01

    以短芒大麦草为研究对象,利用传统培养法从叶围和青贮发酵体系中分离出乳酸菌、大肠杆菌、好氧细菌、酵母菌和霉菌,并计数;结合细菌形态学、生理生化特征及16S rDNA 序列分析鉴定分离出的乳酸菌菌株;通过研究乳酸菌的生长曲线、产酸特性及耐酸性,筛选优质乳酸菌。以期探明短芒大麦草叶围及青贮发酵体系中微生物菌群特性及青贮料中乳酸菌多样性,筛选出具有促发酵效果的乳酸菌菌株,为有益微生物饲料研发奠定基础。试验结果表明,短芒大麦草经青贮发酵后各微生物菌群数量发生不同程度变化,乳酸菌数量由0 cfu/g FM 增加到4.00×108 cfu/g FM,酵母菌数量由8.50×105 cfu/g FM 增加到1.02×108 cfu/g FM,而好氧细菌、大肠杆菌和霉菌数量变化不明显;从短芒大麦草青贮发酵体系分离得到4株乳酸菌,经鉴定 Lx36为 Lactobacillus pentosus ,Lx37为 Lactobacillus brevis ,Lx53为 Pediococcus pentosaceus ,Lx54为 Lactobacillus parabuchneri ;筛选得到1株益于青贮的乳酸菌株 Lx36,约在20 h 后进入稳定生长期,OD 值达到4.21,且发酵12 h 的 pH 仅为4.08,并可以在 pH=3.0环境条件下生长。综上所述,青贮发酵是体系中各种微生物相互作用的过程,微生物菌群的数量及变化直接影响青贮饲料发酵品质。短芒大麦草青贮饲料中乳酸菌种类较丰富,筛选得到的戊糖乳杆菌繁殖速度快、产酸能力强同时表现出了较强的耐酸性,具有潜在的生产应用价值,适宜用作促发酵的青贮添加剂菌种。%A study has been undertaken to investigate the microbial community structure,microorganism popu-lations and diversity of lactic acid bacteria in Hordeum brevisubulatum silage.Lactic acid bacteria,coliform bacteria,aerobic bacteria,yeast and mold were isolated and counted by means of selective media.Lactic acid

  14. Influence of epiphytic bacteria from grapevine leaves on Phomopsis viticola Sacc.

    Directory of Open Access Journals (Sweden)

    Ewa Król

    2013-12-01

    Full Text Available Out of 282 isolates of epiphytic bacteria population originating from grapevine leaves 15% inhibited growth of Phomopsis viticola on potato-dextrose agar. Protective activity of 16 isolates, representing different morphological groups was tested on one-year old of grapevine stems fragments. Majority of bacterial isolates which inhibited the fungus growth in-vitro provided no protection of stems fragments against P. viticola. The efficiency of protection activity of bacterial isolates tested decreased with time. The most effective isolates of bacteria in protection of grapevine stemswere identified as Bacillus sp. and Pseudomonas fluorescens.

  15. Concurrent Phosphorus Recovery and Energy Generation in Mediator-Less Dual Chamber Microbial Fuel Cells: Mechanisms and Influencing Factors.

    Science.gov (United States)

    Almatouq, Abdullah; Babatunde, Akintunde O

    2016-03-29

    This study investigated the mechanism and key factors influencing concurrent phosphorus (P) recovery and energy generation in microbial fuel cells (MFC) during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite when ammonium and magnesium chloride solutions were added to the cathode chamber. Monitoring data for chemical oxygen demand (COD), pH, oxidation reduction potential (ORP) and aeration flow rate showed that a maximum 38% P recovery was achieved; and this corresponds to 1.5 g/L, pH > 8, -550 ± 10 mV and 50 mL/min respectively, for COD, pH(cathode), ORP and cathode aeration flow rate. More importantly, COD and aeration flow rate were shown to be the key influencing factors for the P recovery and energy generation. Results further show that the maximum P recovery corresponds to 72 mW/m² power density. However, the energy generated at maximum P recovery was not the optimum; this shows that whilst P recovery and energy generation can be concurrently achieved in a microbial fuel cell, neither can be at the optimal value.

  16. Concurrent Phosphorus Recovery and Energy Generation in Mediator-Less Dual Chamber Microbial Fuel Cells: Mechanisms and Influencing Factors

    Directory of Open Access Journals (Sweden)

    Abdullah Almatouq

    2016-03-01

    Full Text Available This study investigated the mechanism and key factors influencing concurrent phosphorus (P recovery and energy generation in microbial fuel cells (MFC during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite when ammonium and magnesium chloride solutions were added to the cathode chamber. Monitoring data for chemical oxygen demand (COD, pH, oxidation reduction potential (ORP and aeration flow rate showed that a maximum 38% P recovery was achieved; and this corresponds to 1.5 g/L, pH > 8, −550 ± 10 mV and 50 mL/min respectively, for COD, pHcathode, ORP and cathode aeration flow rate. More importantly, COD and aeration flow rate were shown to be the key influencing factors for the P recovery and energy generation. Results further show that the maximum P recovery corresponds to 72 mW/m2 power density. However, the energy generated at maximum P recovery was not the optimum; this shows that whilst P recovery and energy generation can be concurrently achieved in a microbial fuel cell, neither can be at the optimal value.

  17. Influence of river discharge on abundance and dissemination of heterotrophic, indicator and pathogenic bacteria along the East Coast of India.

    Science.gov (United States)

    Prasad, V R; Srinivas, T N R; Sarma, V V S S

    2015-06-15

    In order to examine the influence of discharge from different rivers from peninsular India and urban sewage on intensity and dissemination of heterotrophic, indicator and pathogenic bacteria, a study was carried out during peak discharge period along coastal Bay of Bengal. The coastal Bay received freshwater inputs from the river Ganges while Godavari and Krishna contributed to the south. Contrasting difference in salinity, temperature, nutrients and organic matter was observed between north and south east coast of India. The highest heterotrophic, indicator and pathogenic bacterial abundance was observed in the central coastal Bay that received urban sewage from the major city. Intensity and dissemination of heterotrophic, indicator and pathogenic bacteria displayed linear relation with magnitude of discharge. The coliform load was observed up to 100km from the coast suggesting that marine waters were polluted during the monsoon season and its impact on the ecosystem needs further studies. PMID:25934433

  18. Distinctive colonization of Bacillus sp. bacteria and the influence of the bacterial biofilm on electrochemical behaviors of aluminum coatings.

    Science.gov (United States)

    Abdoli, Leila; Suo, Xinkun; Li, Hua

    2016-09-01

    Formation of biofilm is usually essential for the development of biofouling and crucially impacts the corrosion of marine structures. Here we report the attachment behaviors of Bacillus sp. bacteria and subsequent formation of bacterial biofilm on stainless steel and thermal sprayed aluminum coatings in artificial seawater. The colonized bacteria accelerate the corrosion of the steel plates, and markedly enhance the anti-corrosion performances of the Al coatings in early growth stage of the bacterial biofilm. After 7days incubation, the biofilm formed on the steel is heterogeneous while exhibits homogeneous feature on the Al coating. Atomic force microscopy examination discloses inception of formation of local pitting on steel plates associated with significantly roughened surface. Electrochemical testing suggests that the impact of the bacterial biofilm on the corrosion behaviors of marine structures is not decided by the biofilm alone, it is instead attributed to synergistic influence by both the biofilm and physicochemical characteristics of the substratum materials.

  19. Distinctive colonization of Bacillus sp. bacteria and the influence of the bacterial biofilm on electrochemical behaviors of aluminum coatings.

    Science.gov (United States)

    Abdoli, Leila; Suo, Xinkun; Li, Hua

    2016-09-01

    Formation of biofilm is usually essential for the development of biofouling and crucially impacts the corrosion of marine structures. Here we report the attachment behaviors of Bacillus sp. bacteria and subsequent formation of bacterial biofilm on stainless steel and thermal sprayed aluminum coatings in artificial seawater. The colonized bacteria accelerate the corrosion of the steel plates, and markedly enhance the anti-corrosion performances of the Al coatings in early growth stage of the bacterial biofilm. After 7days incubation, the biofilm formed on the steel is heterogeneous while exhibits homogeneous feature on the Al coating. Atomic force microscopy examination discloses inception of formation of local pitting on steel plates associated with significantly roughened surface. Electrochemical testing suggests that the impact of the bacterial biofilm on the corrosion behaviors of marine structures is not decided by the biofilm alone, it is instead attributed to synergistic influence by both the biofilm and physicochemical characteristics of the substratum materials. PMID:27289310

  20. Influence of Pig Slurry on Microbial and Biochemical Characteristics of Soil in Albacete Region, SE Spain

    Science.gov (United States)

    Halil Yanardaǧ, Ibrahim

    2013-04-01

    Soil quality is very important in terms of agricultural sustainability, ecosystem and terrestrial carbon (C) cycle. In turn, soil microbial and biochemical characteristics are indicative of nutrient cycling and soil organic matter dynamics. We investigated the effects of the pig slurries (raw pig slurry (RPS) and treated pig slurry (TPS) from liquid and solid feeding diets) on microbial and biochemical characteristics of soil under barley cropping system. Application doses of slurries are identified with legal doses of Castilla La Mancha Region, which is 210 kg N ha-1 year-1. Microbial biomass C, soluble C, black C and three soil enzymes (β-Glucosidase, β-galactosidase and Arylesterase enzymes) are studied to determine effect slurry on soil biochemical characteristics, which are very important in terms of C cycle in soil. Black carbon content and β-Glucosidase enzyme activities are increased with all pig slurry applications from liquid and traditional feeding diet, as well as microbial biomass and organic carbon content and β-galactosidase enzyme activities are increased with slurry from liquid feeding diet doses. However, pig slurry application from liquid feeding diet doses have increased yield, quality, length and total biomass content of barley. Bioavailable metal contents are increased with all slurry application and with using high doses of slurry can be caused soil pollution. Pig slurries from liquid feeding diet had positive impacts on microbial and biochemical characteristics in terms of soil quality in comparison to the different feeding diets. PS addition to soil had a very significant stimulating effect on the enzyme activities, microbial biomass, soluble and black C compared with different kind of PS and control plots on Mediterranean soil in barley monoculture. This effect may originate from the organic C, N, P and S compounds added with PS. The highest enzyme activity and microbial biomass were observed on the soil samples from the RPS treatment

  1. Application' and validation of autochthonous lactic acid bacteria starter cultures for controlled leek fermentations and their influence on the antioxidant properties of leek.

    Science.gov (United States)

    Wouters, D; Bernaert, N; Anno, N; Van Droogenbroeck, B; De Loose, M; Van Bockstaele, E; De Vuyst, L

    2013-07-15

    Leek (Allium ampeloprasum var. porrum) is one of Belgium's most important outdoor vegetables, mainly cultivated for its white shaft. Fermentation of leek offers opportunities in view of biomass valorization and product diversification. This study deals with the implementation and validation of starter cultures to perform controlled leek fermentations and to ensure a high quality of the end-products. Therefore, a thorough study of the fermentation microbiology and the influence of three starter culture strains (Lactobacillus plantarum IMDO 788, Lactobacillus sakei IMDO 1358, and Leuconostoc mesenteroides IMDO 1347) on the metabolite kinetics of leek fermentation and antioxidant properties of leek was performed. Overall, the application of lactic acid bacteria starter cultures resulted in a fast prevalence of the species involved, coupled to an accelerated acidification. Of the three starter cultures tested, the mixed starter culture of L. plantarum IMDO 788 and L. mesenteroides IMDO 1347 was most promising, as its application resulted in fermented leek of good microbiological quality and in a more extensive carbohydrate consumption, whereby diverse end-metabolites were produced. However, high residual fructose concentrations allowed yeast outgrowth, resulting in increased ethanol and glycerol concentrations, and indicated the lack of a prevailing strictly heterofermentative LAB species. The antioxidant capacity of fermented leek samples, as measured with the oxygen radical absorbance capacity assay, increased when starter cultures were used, whereas with regard to 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, only leek fermented with L. sakei IMDO 1358 scored higher than spontaneously fermented leek. The total phenolic content was not influenced by the use of starter cultures, while the S-alk(en)yl-L-cysteine sulfoxides content decreased strongly. A preliminary sensory analysis revealed that the spontaneously fermented leek and the one obtained

  2. Microbial-Influenced Corrosion of Corten Steel Compared with Carbon Steel and Stainless Steel in Oily Wastewater by Pseudomonas aeruginosa

    Science.gov (United States)

    Mansouri, Hamidreza; Alavi, Seyed Abolhasan; Fotovat, Meysam

    2015-07-01

    The microbial corrosion behavior of three important steels (carbon steel, stainless steel, and Corten steel) was investigated in semi petroleum medium. This work was done in modified nutrient broth (2 g nutrient broth in 1 L oily wastewater) in the presence of Pseudomonas aeruginosa and mixed culture (as a biotic media) and an abiotic medium for 2 weeks. The behavior of corrosion was analyzed by spectrophotometric and electrochemical methods and at the end was confirmed by scanning electron microscopy. The results show that the degree of corrosion of Corten steel in mixed culture, unlike carbon steel and stainless steel, is less than P. aeruginosa inoculated medium because some bacteria affect Corten steel less than other steels. According to the experiments, carbon steel had less resistance than Corten steel and stainless steel. Furthermore, biofilm inhibits separated particles of those steels to spread to the medium; in other words, particles get trapped between biofilm and steel.

  3. Effect of the surface treatment on microbially influenced corrosion resistance of stainless steels; Taibiseibutsu fushokusei ni oyobosu stainless ko no hyomen shori no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, H.; Miyuki, H. [Sumitomo Metal Industries, Ltd., Osaka (Japan)

    1997-06-20

    This paper describes the corrosion potential ennoblement behavior of stainless steel with various surface treatments and the effects of surface treatment on the microbially influenced corrosion (MIC) by means of simulated MIC reproduction test method in the laboratory. SUS316L steels were polished, passivated, electropolished, and electrolyzed in Fe(III)Cr(VI) containing solution and in sulfuric acid. For the specimens polished, passivated, electropolished and electrolyzed in sulfuric acid, the corrosion potential was ennobled in the MIC test solution, and crevice corrosion was generated in the seawater. For the specimen electrolyzed in Fe(III)Cr(VI) containing solution, the corrosion potential was ennobled only in a degree of standard electrode, and crevice corrosion was not observed. The film on the steel surface had a double layer structure composing of the Fe hydride outer layer and the Cr oxide inner layer. The cathodic polarization reaction of the bipolar membrane, which consisted of outer anion selective layer and inner cation selective layer, was suppressed. The corrosion potential ennoblement due to the promotion of cathodic polarization reaction by bacteria was suppressed. Thus, excellent anti-MIC property was demonstrated. 17 refs., 11 figs., 5 tabs.

  4. Influence of Oxygen and Nitrate on Fe (Hydr)oxide Mineral Transformation and Soil Microbial Communities during Redox Cycling.

    Science.gov (United States)

    Mejia, Jacqueline; Roden, Eric E; Ginder-Vogel, Matthew

    2016-04-01

    Oscillations between reducing and oxidizing conditions are observed at the interface of anaerobic/oxic and anaerobic/anoxic environments, and are often stimulated by an alternating flux of electron donors (e.g., organic carbon) and electron acceptors (e.g., O2 and NO3(-)). In iron (Fe) rich soils and sediments, these oscillations may stimulate the growth of both Fe-reducing bacteria (FeRB) and Fe-oxidizing bacteria (FeOB), and their metabolism may induce cycling between Fe(II) and Fe(III), promoting the transformation of Fe (hydr)oxide minerals. Here, we examine the mineralogical evolution of lepidocrocite and ferrihydrite, and the adaptation of a natural microbial community to alternating Fe-reducing (anaerobic with addition of glucose) and Fe-oxidizing (with addition of nitrate or air) conditions. The growth of FeRB (e.g., Geobacter) is stimulated under anaerobic conditions in the presence of glucose. However, the abundance of these organisms depends on the availability of Fe(III) (hydr)oxides. Redox cycling with nitrate results in decreased Fe(II) oxidation thereby decreasing the availability of Fe(III) for FeRB. Additionally, magnetite is detected as the main product of both lepidocrocite and ferrihydrite reduction. In contrast, introduction of air results in increased Fe(II) oxidation, increasing the availability of Fe(III) and the abundance of Geobacter. In the lepidocrocite reactors, Fe(II) oxidation by dissolved O2 promotes the formation of ferrihydrite and lepidocrocite, whereas in the ferrihydrite reactors we observe a decrease in magnetite stoichiometry (e.g., oxidation). Understanding Fe (hydr)oxide transformation under environmentally relevant redox cycling conditions provides insight into nutrient availability and transport, contaminant mobility, and microbial metabolism in soils and sediments. PMID:26949922

  5. Role of a unique population of lithotrophic, Fe-oxidizing bacteria in forming microbial Fe-mats at the Loihi Seamount.

    Science.gov (United States)

    Emerson, D.; Rentz, J. A.; Moyer, C. L.

    2005-12-01

    The Loihi Seamount, located 30 km SE of the island of Hawai'i, is among the most active volcanos on Earth. The summit, at a depth of 1100m, includes a 250m deep caldera (Pele's Pit) formed by an eruption in 1996. The summit, and especially Pele's Pit, are the site of extensive low to intermediate temperature (10° to 65°C) hydrothermal venting, emanating both from diffuse fissures and orifices that have substantial flow rates. The vent fluid is characterized by a low sulfide content, high CO2 concentrations and Fe(II) amounts in the 10s to 100s of μM. Associated with all vents are extensive deposits of iron oxyhydroxides that typically have 107 to 108 bacterial cells/cc associated with them. The morphology of the Fe-oxides are indicative of biological origins. We have isolated microaerophilic, obligately lithotrophic Fe-oxidizing bacteria from Loihi and describe here `Mariprofundus ferroxydans' a unique bacterium that forms a filamentous iron oxide mineral. `M. ferroxydans' is the first cultured representative of a novel division of the Proteobacteria, known previously only from clones from different hydrothermal vent sites. Molecular evidence from Loihi mats based on clone libraries and terminal restriction length polymorphism (T-RFLP) analysis of 16S rRNA genes indicate that this lineage of Fe-oxidizing organisms are common inhabitants at Loihi. We speculate that this organism and its relatives form the basis of an active microbial mat community that owe their existence to the inherent gradients of Fe(II) and O2 that exist at the Loihi vents. In a geological context this is interesting because the Loihi summit and caldera are in an O2-minima zone; O2 concentrations in the bulk seawater are around 0.5 mg/l. In effect, Loihi could serve as a proxy for the late Archaean and early Proterozoic periods when the Earth's atmosphere went from reducing to oxidizing, and it is speculated that abundant Fe(II) in the Earth's oceans served as a major sink for O2 production

  6. Influence of microbial activity on the migration behaviour of redox-sensitive radionuclides (technetium and selenium) in loose rock

    International Nuclear Information System (INIS)

    In closed cycle column tests under sterile conditions there was no or hardly any sorption of the two radionuclides. In closed cycle column tests with unsterile soils, however, the two radionuclides were extremely immobilised (80 % of the output activity of Tc-95m and 40 % of the output activity of Se-75). By inoculation of the sterile columns with mixed soil cultures an increase in sorption of 40 % of the output activity was achieved which is attributed to the microbial activity. The adsorbed radionuclides in unsterile columns could be remobilized by adding a bactericide. In columns with saline water the sorption of radionuclides was slightly lower. Soils with a 5 % organic carbon content showed extremely increased sorption of the two radionuclides. In comparison with closed cycle columns shake tests were carried out. During turbulent intermixing of water and solid, no sorption of technetium was observed in unsterile tests either, while Se-75 added as selenite was strongly adsorbed to the solid. When adding acetate as a C-source, the microbially conditioned reduction of the redox potential to -100 mV and, subsequently, a strong increase of sorption could be observed. A reduction of the pH value in the soils to pH 4, and simultaneous adding of acetate significally reduced the microbial activity and the sorption of technetium, while selenite sorption remained strong as before. Sorption tests with bacteria-pure and mixed cultures showed no sorption of the pertechnetate anion in the oxidation stage (VII). However, when reducing the pertechnetate by means of SnCl2, up to 40 % of the feed activity of killed and living biomass was immobilized. Between 20-30 % of the adsorbed technetium quantity was outside at the membrane, and 40% inside the cells. After a three-day incubation period in a technetium-containing solution, a factor of 15,5 was achieved as the maximum intracellular concentration factor for the isolate 143 (Xanthomas sp.). (orig./MG)

  7. Influence of substrate on electricity generation of Shewanella loihica PV-4 in microbial fuel cells

    Science.gov (United States)

    2014-01-01

    Background The substrate, serving as carbon and energy source, is one of the major factors affecting the performance of microbial fuel cells (MFCs). We utilized BIOLOG system to rapidly screen substrates for electricigens, and further evaluated influence of these substrates on electricity generation of Shewanella loihica PV-4 in MFCs. Results Three of most favorable substrates (lactate acid, formic acid and cyclodextrin) with OD590/750 of 0.952, 0.880 and 0.849 as well as three of most unfavorable substrates (galactose, arabinose and glucose) with OD590/750 of 0.248, 0.137 and 0.119 were selected by BIOLOG system under aerobic conditions. The chronoamperometry results showed that MFCs fed with these substrates exhibited different current behaviors. Cyclic voltammograms results showed that arabinose, galactose and glucose promoted electron transfer from outer membrane c-Cyts of cells to the electrode surface. Lactic acid, formic acid and cyclodextrin produced lower quantity of electric charge of 10.13 C, 9.83 C and 10.10 C, the corresponding OD600 value was 0.180, 0.286 and 0.152 in BES; while galactose, arabinose and glucose generated higher quantity of electric charge of 12.34 C, 13.42 C and 17.45 C, and increased OD600 values were 0.338, 0.558 and 0.409 in BES. SEMs results showed that plenty of plump and stretched cells as well as appendages were observed when lactic acid, formic acid, and cyclodextrin were utilized as substrates, while sparse cells in short shape were obtained when galactose, arabinose and glucose were used as substrates. Conclusions These results suggest that substrate not only has important role in electrochemical performances of MFCs but also in biological properties of electricigens. Lactic acid, formic acid, and cyclodextrin beneficial for cell growth under aerobic conditions are unfavourable for planktonic cell growth and current generation under anaerobic conditions, while consumptions of galactose, arabinose and glucose adverse to cell

  8. Influence of increasing dissolved inorganic carbon concentrations and decreasing pH on chemolithoautrophic bacteria from oxic-sulfidic interfaces

    Directory of Open Access Journals (Sweden)

    K. Mammitzsch

    2012-12-01

    Full Text Available Increases in the dissolved inorganic carbon (DIC concentration are expected to cause a decrease in the pH of ocean waters, a process known as ocean acidification. In oxygen-deficient zones this will add to already increased DIC and decreased pH values. It is not known how this might affect microbial communities and microbially mediated processes. In this study, the potential effects of ocean acidification on chemolithoautotrophic prokaryotes of marine oxic-anoxic transition zones were investigated, using the chemoautotrophic denitrifying ε-proteobacterium "Sulfurimonas gotlandica" strain GD1 as a model organism. This and related taxa use reduced sulfur compounds, e.g. sulfide and thiosulfate, as electron donors and were previously shown to be responsible for nitrate removal and sulfide detoxification in redox zones of the Baltic Sea water column but occur also in other oxygen-deficient marine systems. Bacterial cell growth within a broad range of DIC concentrations and pH values was monitored and substrate utilization was determined. The results showed that the DIC saturation concentration for growth was already reached at 800 μM, which is well below in situ DIC levels. The pH optimum was between 6.6 and 8.0. Within a pH range of 6.6–7.1 there was no significant difference in substrate utilization; however, at lower pH values cell growth decreased sharply and cell-specific substrate consumption increased. These findings suggest that a direct effect of ocean acidification, with the predicted changes in pH and DIC, on chemolithoautotrophic bacteria such as "S. gotlandica" str. GD1 is generally not very probable.

  9. Influence of increasing dissolved inorganic carbon concentrations and decreasing pH on chemolithoautrophic bacteria from oxic-sulfidic interfaces

    Science.gov (United States)

    Mammitzsch, K.; Jost, G.; Jürgens, K.

    2012-12-01

    Increases in the dissolved inorganic carbon (DIC) concentration are expected to cause a decrease in the pH of ocean waters, a process known as ocean acidification. In oxygen-deficient zones this will add to already increased DIC and decreased pH values. It is not known how this might affect microbial communities and microbially mediated processes. In this study, the potential effects of ocean acidification on chemolithoautotrophic prokaryotes of marine oxic-anoxic transition zones were investigated, using the chemoautotrophic denitrifying ɛ-proteobacterium "Sulfurimonas gotlandica" strain GD1 as a model organism. This and related taxa use reduced sulfur compounds, e.g. sulfide and thiosulfate, as electron donors and were previously shown to be responsible for nitrate removal and sulfide detoxification in redox zones of the Baltic Sea water column but occur also in other oxygen-deficient marine systems. Bacterial cell growth within a broad range of DIC concentrations and pH values was monitored and substrate utilization was determined. The results showed that the DIC saturation concentration for growth was already reached at 800 μM, which is well below in situ DIC levels. The pH optimum was between 6.6 and 8.0. Within a pH range of 6.6-7.1 there was no significant difference in substrate utilization; however, at lower pH values cell growth decreased sharply and cell-specific substrate consumption increased. These findings suggest that a direct effect of ocean acidification, with the predicted changes in pH and DIC, on chemolithoautotrophic bacteria such as "S. gotlandica" str. GD1 is generally not very probable.

  10. Synergistic influence of Vetiveria zizanioides and selected rhizospheric microbial strains on remediation of endosulfan contaminated soil.

    Science.gov (United States)

    Singh, Vandana; Singh, Pratiksha; Singh, Nandita

    2016-09-01

    Application of endosulfan tolerant rhizospheric bacterial strain isolated from pesticide contaminated area, Ghaziabad in combination with V. zizanioides for the remediation of endosulfan is described herein. The dissipation of endosulfan from soil was considerably enhanced in the presence of bacterial strain and Vetiveria zizanioides together when compared to the dissipation in presence of either of them alone. Four strains- EAG-EC-12 (M1), EAG-EC-13(M2), EAG-EC-14(M3) and EAG-EC-15(M4) are used for this purpose. V. zizanioides was grown in garden soil spiked with 1500 µg g(-1) of endosulfan and inoculated with 100 ml of microbial culture of above motioned strains. Effect of microbial inoculation on plant growth, endosulfan uptake and endosulfan removal efficiency were analyzed. The microbial inoculation significantly enhances the growth of test plant and endosulfan dissipation from soil (p contaminated soil. PMID:27300249

  11. Can the development and autolysis of lactic acid bacteria influence the cheese volatile fraction? The case of Grana Padano.

    Science.gov (United States)

    Lazzi, Camilla; Povolo, Milena; Locci, Francesco; Bernini, Valentina; Neviani, Erasmo; Gatti, Monica

    2016-09-16

    In this study, the relationship between the dynamics of the growth and lysis of lactic acid bacteria in Grana Padano cheese and the formation of the volatile flavor compounds during cheese ripening was investigated. The microbial dynamics of Grana Padano cheeses that were produced in two different dairies were followed during ripening. The total and cultivable lactic microflora, community composition as determined by length heterogeneity-PCR (LH-PCR), and extent of bacterial lysis using an intracellular enzymatic activity assay were compared among cheeses after 2, 6 and 13months of ripening in two dairies. The evolution of whole and lysed microbiota was different between the two dairies. In dairy 2, the number of total cells was higher than that in dairy 1 in all samples, and the number of cells that lysed during ripening was lower. In addition, at the beginning of ripening (2months), the community structure of the cheese from dairy 2 was more complex and was composed of starter lactic acid bacteria (Lactobacillus helveticus and Lactobacillus delbrueckii) and NSLAB, possibly arising from raw milk, including Lactobacillus rhamnosus/Lactobacillus casei and Pediococcus acidilactici. On the other hand, the cheese from dairy 1 that ripened for 2months was mainly composed of the SLAB L. helveticus and L. delbrueckii. An evaluation of the free-DNA fraction through LH-PCR identified those species that had a high degree of lysis. Data on the dynamics of bacterial growth and lysis were evaluated with respect to the volatile profile and the organic acid content of the two cheeses after 13months of ripening, producing very different results. Cheese from dairy 1 showed a higher content of free fatty acids, particularly those deriving from milk fat lipolysis, benzaldehyde and organic acids, such as pGlu and citric. In contrast, cheese from dairy 2 had a greater amount of ketones, alcohols, hydrocarbons, acetic acid and propionic acid. Based on these results, we can conclude that

  12. Initial steps in the microbially influenced corrosion (MIC) of metallic surfaces in a natural marine environment

    International Nuclear Information System (INIS)

    Immersion of various metal samples in polluted seawater from Tenerife Harbor was followed by microbial attachment as an intermediate step in fouling development. The purpose of this research was to determine the initial steps in MIC by identifying the different microbial species attached to the respective metal or alloy. Image analysis was used to determine the morphologic changes in the metal surfaces. The corrosion products were determined by X-ray diffraction. The open circuit potentials were measured periodically and their variation with time used to assess the electrochemical behavior in the aforementioned marine environment

  13. The Pomegranate: Effects on Bacteria and Viruses That Influence Human Health

    OpenAIRE

    Amy B. Howell; Doris H. D'Souza

    2013-01-01

    Pomegranates have been known for hundreds of years for their multiple health benefits, including antimicrobial activity. The recent surge in multidrug-resistant bacteria and the possibility of widespread global virus pandemics necessitate the need for additional preventative and therapeutic options to conventional drugs. Research indicates that pomegranates and their extracts may serve as natural alternatives due to their potency against a wide range of bacterial and viral pathogens. Nearly e...

  14. Influence Of Associations Of Soil Bacteria On The Structure And Productivity Of Spring Wheat

    OpenAIRE

    Kulnazarov Batyr; Kuznetsova Tatyana

    2015-01-01

    The soil and climatic conditions of the Zhambyl region was verified the growth promoting activity of spring wheat plant associations of soil bacteria (№27, 44, 62). The experiments revealed that the association selected enhance germination, productivity and structure of the spring wheat crop. When preplant treatment of seeds field germination associations increased 4, 3-8, 3 % yield increase of 10,2% - 22,9 %, as well as improved seed quality indicators compared to the control.

  15. Influence Of Associations Of Soil Bacteria On The Structure And Productivity Of Spring Wheat

    Directory of Open Access Journals (Sweden)

    Kulnazarov Batyr,

    2015-09-01

    Full Text Available The soil and climatic conditions of the Zhambyl region was verified the growth promoting activity of spring wheat plant associations of soil bacteria (№27, 44, 62. The experiments revealed that the association selected enhance germination, productivity and structure of the spring wheat crop. When preplant treatment of seeds field germination associations increased 4, 3-8, 3 % yield increase of 10,2% - 22,9 %, as well as improved seed quality indicators compared to the control.

  16. A review of the influence of treatment strategies on antibiotic resistant bacteria and antibiotic resistance genes.

    Science.gov (United States)

    Sharma, Virender K; Johnson, Natalie; Cizmas, Leslie; McDonald, Thomas J; Kim, Hyunook

    2016-05-01

    Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) in the aquatic environment have become an emerging contaminant issue, which has implications for human and ecological health. This review begins with an introduction to the occurrence of ARB and ARG in different environmental systems such as natural environments and drinking water resources. For example, ARG or ARB with resistance to ciprofloxacin, sulfamethoxazole, trimethoprim, quinolone, vancomycin, or tetracycline (e.g., tet(A), tet(B), tet(C), tet(G), tet(O), tet(M), tet(W), sul I, and sul II) have been detected in the environment. The development of resistance may be intrinsic, may be acquired through spontaneous mutations (de novo), or may occur due to horizontal gene transfer from donor bacteria, phages, or free DNA to recipient bacteria. An overview is also provided of the current knowledge regarding inactivation of ARB and ARG, and the mechanism of the effects of different disinfection processes in water and wastewater (chlorination, UV irradiation, Fenton reaction, ozonation, and photocatalytic oxidation). The effects of constructed wetlands and nanotechnology on ARB and ARG are also summarized. PMID:26775188

  17. The influence of dietary microbial phytase and calcium on the accumulation of cadmium in different organs of pigs

    Energy Technology Data Exchange (ETDEWEB)

    Zacharias, B.; Lantzsch, H.J.; Drochner, W. [Hohenheim Univ., Stuttgart (Germany). Inst. fuer Tierernaehrung

    2001-07-01

    A total of 72 barrows (initial body weight 16.7 kg) was used, to evaluate the influence of microbial phytase supplementation alone or in combination with calcium to barley soybean meal diets on the accumulation of cadmium (Cd) in kidney, liver, muscle, brain and bone. The control group received the basal diet with 6 g Ca and a low native Cd concentration of 0.03 mg/kg dry matter (DM). In the experimental groups 2, 3, 4 and 5 dietary cadmium concentration was elevated to 0.78 mg/kg DM. The diet of group 3 was supplemented with 800 U microbial phytase/kg, the diet of group 4 with 6 g Ca/kg. The diet of group 5 contained both supplements. The addition of microbial phytase caused an increase of Cd retention in kidney and liver at 30 and 50 kg body weight. This effect was counteracted by the contemporary addition of calcium. A supplementation of Ca alone showed no effect on the Cd accumulation in kidney and liver. In muscle, brain and bone no effects of phytase and calcium on the accumulation of Cd could be found. (orig.)

  18. Thermal and geochemical influences on microbial biogeography in the hydrothermal sediments of Guaymas Basin, Gulf of California.

    Science.gov (United States)

    McKay, Luke; Klokman, Vincent W; Mendlovitz, Howard P; LaRowe, Douglas E; Hoer, Daniel R; Albert, Daniel; Amend, Jan P; Teske, Andreas

    2016-02-01

    Extreme thermal gradients and compressed metabolic zones limit the depth range of microbial colonization in hydrothermally active sediments at Guaymas Basin. We investigated the physicochemical characteristics of this ecosystem and their influence on microbial community structure. Temperature-related trends of δ(13)C values of methane and dissolved inorganic carbon from 36 sediment cores suggest in situ thermal limits for microbial anaerobic methane oxidation and organic carbon re-mineralization near 80°C and 100°C respectively. Temperature logging probes deposited in hydrothermal sediments for 8 days demonstrate substantial thermal fluctuations of up to 25°C. Putative anaerobic methanotroph (ANME) populations dominate the archaeal community, transitioning from ANME-1 archaea in warm surficial sediments towards ANME-1 Guaymas archaea as temperatures increase downcore. Since ANME archaea performing anaerobic oxidation of methane double on longer time scales (months) compared with relatively rapid in situ temperature fluctuations (hours to days), we conclude that ANME archaea possess a high tolerance for short-term shifts in the thermal regime.

  19. Microbially influenced corrosion in cooling water systems. Development of a new protection concept for system components conveying brackish water

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, Simone; Richter, Tobias [E.ON Kernkraft GmbH, Brokdorf Nuclear Power Plant, Brokdorf (Germany); Nowak, Erika [E.ON Kernkraft GmbH, Hannover (Germany)

    2009-07-01

    Corrosive findings ascribed to microbially influenced corrosion (MIC), have been increasingly observed on cooling water systems in Northern German nuclear power plants. By means of a research programme (field tests), high-alloyed materials with different pitting resistance equivalent numbers (PREN), various surface finishing and various coatings were evaluated, based on microbiological preliminary research, with respect to their corrosion behaviour in natural brackish water. Subsequent material evaluations, in combination with other measures, provided a new standard of knowledge for the development of a protection concept for components conveying brackish water. (orig.)

  20. Use of Homogeneously-Sized Carbon Steel Ball Bearings to Study Microbially-Influenced Corrosion in Oil Field Samples

    OpenAIRE

    Gerrit eVoordouw; Priyesh eMenon; Tijan ePinnock; Mohita eSharma; Yin eShen; Amanda eVenturelli; Johanna eVoordouw; Aoife eSexton

    2016-01-01

    Microbially-influenced corrosion (MIC) contributes to the general corrosion rate (CR), which is typically measured with carbon steel coupons. Here we explore the use of carbon steel ball bearings, referred to as beads (55.0 ± 0.3 mg; Ø = 0.238 cm), for determining CRs. CRs for samples from an oil field in Oceania incubated with beads were determined by the weight loss method, using acid treatment to remove corrosion products. The release of ferrous and ferric iron was also measured and CRs ba...

  1. The veterinary antibiotic oxytetracycline and Cu influence functional diversity of the soil microbial community

    Energy Technology Data Exchange (ETDEWEB)

    Kong, W.-D. [Research Center for Eco-Environmental Sciences, Soil Environment of Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Zhu, Y.-G. [Research Center for Eco-Environmental Sciences, Soil Environment of Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China)]. E-mail: ygzhu@mail.rcees.ac.cn; Fu, B.-J. [Research Center for Eco-Environmental Sciences, Soil Environment of Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Marschner, P. [Soil and Land Systems, School of Earth and Environmental Sciences, University of Adelaide, DP 636, 5005 (Australia); He, J.-Z. [Research Center for Eco-Environmental Sciences, Soil Environment of Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China)

    2006-09-15

    There are increasing concerns over the effects of veterinary antibiotics and heavy metals in agricultural soils. The widely used veterinary antibiotic oxytetracycline (OTC), Cu and their combination on soil microbial community function were assessed with the Biolog method. The microbial community was extracted from the soil and exposed to a 0.85% sodium chloride solution containing OTC (0, 1, 5, 11, 43, 109 and 217 {mu}M), or Cu (0, 10, 20, 100 and 300 {mu}M), or combination of the two pollutants (OTC 0, 5, 11 {mu}M and Cu 0, 20 {mu}M). Functional diversity, evenness, average well color development (AWCD) and substrate utilization decreased significantly with increasing concentrations of OTC or Cu (p < 0.005). The critical concentrations were 11 {mu}M for OTC and 20 {mu}M for Cu. The combination of OTC and Cu significantly decreased Shannon's diversity, evenness and utilization of carbohydrates and carboxylic acids compared to individual one of the contaminants. The antibiotic OTC and Cu had significant negative effects on soil microbial community function, particularly when both pollutants were present. - Oxytetracycline reduces the functional diversity of soil microbial community, and the combination of Cu and oxytetracycline leads to a further reduction.

  2. Soil microbial community dynamics as influenced by composted dairy manure, soil properties and landscape position

    Science.gov (United States)

    Understanding factors that affect plant growth, whether it is manure addition, season, or soil-type and landscape variability may also impact soil microbial activity, biomass and community structure. Thus an in situ study was conducted to evaluate microbiological properties of three different soil t...

  3. Influence of different buffers (HEPES/MOPS) on keratinocyte cell viability and microbial growth.

    Science.gov (United States)

    Dias, Kássia de Carvalho; Barbugli, Paula Aboud; Vergani, Carlos Eduardo

    2016-06-01

    This study assessed the effect of the buffers 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 3-(N-morpholino) propanesulfonic acid (MOPS) on keratinocyte cell viability and microbial growth. It was observed that RPMI buffered with HEPES, supplemented with l-glutamine and sodium bicarbonate, can be used as a more suitable medium to promote co-culture. PMID:27060444

  4. A study of microbial population dynamics associated with corrosion rates influenced by corrosion control materials

    NARCIS (Netherlands)

    Chang, Yu Jie; Hung, Chun Hsiung; Lee, Jyh Wei; Chang, Yi Tang; Lin, Fen Yu; Chuang, Chun Jie

    2015-01-01

    This research aims to analyze the variations of microbial community structure under anaerobic corrosive conditions, using molecular fingerprinting method. The effect of adding various materials to the environment on the corrosion mechanism has been discussed. In the initial experiment, sulfate-re

  5. Influence of Gamma Irradiation on Microbial Quality, Biological Properties and Some Chemical Compositions of Propolis and Bee Pollen In Egypt

    International Nuclear Information System (INIS)

    Propolis and bee pollen may be subjected to microbial contamination as a result of handling and storage, so, the current study was conducted to evaluate the microbial quality and quantity of Egyptian propolis and pollen and to study microbial contamination, antimicrobial activity, antioxidant activity and some chemical properties as amino acid composition and mineral content of irradiated and non-irradiated tested samples.The results showed that most samples were of unsatisfactory microbiological quality where the total bacterial and mold and yeast counts ranged between 6.6x10-6x106 CFU/g and 1.2 x 103-3.7x103 CFU/g, respectively. Agar disk diffusion method was used for in vitro antimicrobial evaluation of propolis and pollen using water and 70% ethanolic extract against four gram positive, three gram negative bacteria and one yeast pathogens. The results exhibited that ethanolic extract has effective antibacterial activities than water extract. The free radical-scavenging activity of 70% ethanolic extract of the tested samples was determined using 1,1-diphenyl-2-picryl hydrazyl (DPPH). Pollen ethanolic extract showed higher antioxidant activity than propolis ethanolic extract. Amino acid profile of 70% ethanolic extract was determined. The results of the analysis showed the predominant amino acids in propolis and pollen were cystine and leucine, respectively. Mineral analysis of the tested samples was carried out by atomic absorption. The tested minerals were higher in pollen than in propolis except manganese and selenium. Propolis and pollen heavily bacterial and mold contaminated samples were subjected to increasing doses of gamma radiation (1-5 kGy). Exposure to 4 kGy was sufficient for microbial decontamination or reducing the count less than 10 CFU/g with no detectable effect on their antimicrobial activity. The same irradiation dose showed variable effects on amino acids and mineral content of the tested samples. Propolis and pollen have pharmacological

  6. Microbially influenced corrosion in district heating plants: Best available practice for monitoring, control and prevention; Mikrobielt betinget korrosion i fjernvarmeanlaeg. Bedste tilgaengelige praksis for overvaegning, bekaempelse og forebyggelse

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    Acknowledgement of the fact that corrosion is not only a consequence of chemical and physical conditions, but a dynamic process influenced by the biology in the system, is overall the primary prerequisite for handling of microbial influenced corrosion (MBC). This report describes the procedures and practical precautions which are considered to be best available practice for handling MBC in district heating systems. (BA)

  7. The influence of substrate on siderophore production by fish spoilage bacteria

    DEFF Research Database (Denmark)

    Gram, Lone

    1996-01-01

    Siderophore production of fish spoilage bacteria (5 isolates of Shewanella putrefaciens and 5 of Pseudomonas sp.) was determined in fish extract, Tris-succinate medium, a liquid medium of the Chrome-Azurol-S (CAS) agar and in M9 medium supplemented with glucose and casamino acids (M9GC). One...... isolates. S. putrefaciens produced siderophores of the hydroxamate type in fish extract and to a lesser extend in the M9GC medium. Growth was supported by the other media. S. putrefaciens grew weakly on the Chrome-azurol-S (CAS agar as this medium did not support siderophore-production. However...

  8. The influence of stress conditions on the growth of selected lactic acid bacteria

    International Nuclear Information System (INIS)

    A study was undertaken to determine the effects of certain stress conditions on selected lactic acid bacteria. Where recontamination occurred, lactic acid bacteria was already the dominant bacterial group, with counts of higher than 106/g in vacuum-packaged 'shelf stable' meat products after 1 week storage at 25 and 37 degrees Celsius respectively. Some of the isolates were capable of growing at a pH of 3,9. The minimum pH for growth of a specific culture was dependant on the type of acid that was used to lower the pH. Lactic and acetic acid had the highest inhibitory action. Hydrochloric and citric acid showed similar inhibitory effects, while the effects when using ascorbic acid or gluconic acid for lowering the pH were also fairly similar. Increase in the activity of certain lactic acid bacteria was noticed where the ratio of undissociated to dissociated citric acid in the medium was increased. After exceeding a concentration of 0,048 moles/l undissosiated citric acid in the medium, the activity of the majority of cultures was progressively inhibited. This phenomenon was also found with acetic acid for certain cultures. Selected lactic acid bacteria were resistant to an water activity (a (sub w)) of 0,94 in MRS broth, where NaCl or glycerol was used as a humectant. The minimum a (sub w) for growth was dependent on the type of humectant used. Concentrations of sodium benzoate and potassium sorbate were necessary to inhibit the majority of strains. The % inhibition by sodium benzoate and methyl paraben did not significantly change with a lowering in the pH of the growth medium. Except in the case of lactic acid, the different acids used to lower the pH of the medium did not have a significant effect on the % inhibition by the chemical preservatives. For the cocci, gamma D10 values of between 0,82 and 1,29 kGy were recorded, whereas the lactobacilli were less resistant to gamma rays, with D10 values of between 0,21 and 0,54 kGy

  9. Bovine Host Genetic Variation Influences Rumen Microbial Methane Production with Best Selection Criterion for Low Methane Emitting and Efficiently Feed Converting Hosts Based on Metagenomic Gene Abundance

    OpenAIRE

    Rainer Roehe; Dewhurst, Richard J.; Carol-Anne Duthie; Rooke, John A.; Nest McKain; Dave W Ross; Hyslop, Jimmy J; Anthony Waterhouse; Freeman, Tom C.; Mick Watson; John Wallace, R.

    2016-01-01

    Methane produced by methanogenic archaea in ruminants contributes significantly to anthropogenic greenhouse gas emissions. The host genetic link controlling microbial methane production is unknown and appropriate genetic selection strategies are not developed. We used sire progeny group differences to estimate the host genetic influence on rumen microbial methane production in a factorial experiment consisting of crossbred breed types and diets. Rumen metagenomic profiling was undertaken to i...

  10. Microbial diversity and community structure in an antimony-rich tailings dump.

    Science.gov (United States)

    Xiao, Enzong; Krumins, Valdis; Dong, Yiran; Xiao, Tangfu; Ning, Zengping; Xiao, Qingxiang; Sun, Weimin

    2016-09-01

    To assess the impact of antimony (Sb) on microbial community structure, 12 samples were taken from an Sb tailings pile in Guizhou Province, Southwest China. All 12 samples exhibited elevated Sb concentrations, but the mobile and bioaccessible fractions were small in comparison to total Sb concentrations. Besides the geochemical analyses, microbial communities inhabiting the tailing samples were characterized to investigate the interplay between the microorganisms and environmental factors in mine tailings. In all samples, Proteobacteria and Actinobacteria were the most dominant phyla. At the genus level, Thiobacillus, Limnobacter, Nocardioides, Lysobacter, Phormidium, and Kaistobacter demonstrated relatively high abundances. The two most abundant genera, Thiobacillus and Limnobacter, are characterized as sulfur-oxidizing bacteria and thiosulfate-oxidizing bacteria, respectively, while the genus Lysobacter contains arsenic (As)-resistant bacteria. Canonical correspondence analysis (CCA) indicates that TOC and the sulfate to sulfide ratio strongly shaped the microbial communities, suggesting the influence of the environmental factors in the indigenous microbial communities. PMID:27188777

  11. Influence of Vegetations' Metabolites on the Composition and Functioning of Soil Microbial Complex

    Science.gov (United States)

    Biryukov, Mikhail

    2013-04-01

    Microbiota is one of the major factors of soils fertility. It transforms organic substances in soil and, therefore, serves as the main component in the cycles of carbon and nitrogen. Microbial communities (MC) are characterized as highly diverse and extremely complex structures. This allows them to adapt to any affection and provide all the necessary biospheric functions. Hence, the study of their functional diversity and adaptivity of microbiota provides the key to the understanding of the ecosystems' functioning and their adaptivity to the human impact. The formation of MC at the initial stage is regulated by the fluxes of substrates and biologically active substances (BAS), which vary greatly in soils under different vegetations. These fluxes are presented by: low molecular weights organic substances (LMWOS), which can be directly included in metabolism of microbes; polymers, that can be decomposed to LMWOS by exoenzymes; and more complex compounds, having different "drug effects" (e.g. different types of phenolic acids) and regulating growth and enzymatic properties of microbiota. Therefore, the main hypothesis of the research was formulated as follows: penetration of different types of substrates and BAS into soil leads to the emergence of MC varying in enzymatic properties and structure. As a soil matrix we used the soil from the untreated variant of the lysimeter model experiment taking place in the faculty of Soil Science of the MSU for over the last 40 years. It was sieved with a 2mm sieves, humidified and incubated at 25C during one week. Subsequently, the samples were air-dried with occasional stirring for one more week. Thereafter, aliquots of the prepared soil were taken for the different experimental variants. The samples were rewetted with solutions of various substrates (glucose, cellulose, starch, etc.) and thoroughly mixed. The control variant was established with addition of deionised water. The samples were incubated at the 25C. During the

  12. Mutual influences in growth and reproduction between pine wood nematode Bursaphelenchus xylophilus and bacteria it carries

    Institute of Scientific and Technical Information of China (English)

    ZHAO Boguang; LIU Yutao; LIN Feng

    2006-01-01

    The interactions between pine wood nematode and three bacterium strains isolated from the nematode,Bursaphelenchus xylophilus,which are two strong pathogenic bacterium strains, Pseudomonas fluorescens GcMS-1A and Pseudomonas putida ZpB1-2A and a weak-pathogenic bacterium strain,Pantoea sp.ZM2C,were studied.The result showed that the strong-pathogenic GcM5-1A strain and ZpB 1-2A strain significantly increased fecundity,reproduction rate,and the body volume of the adult nematode.Meanwhile,pine wood nematodes significantly promoted reproduction of the two strong-pathogenic bacterium strains.However,the weak-pathogenic bacterium strain,ZM2C,completely inhibited reproduction of pine wood nematodes.Aseptic pine wood nematodes significantly inhibited reproduction of the strain ZM2C.The results indicated that mutualistic symbiosis exists between pine wood nematodes and the two pathogenic bacteria it carries.The phenomenon showed that the pathogenic bacteria carried by the nematode were not accidentally contaminated,but rather had existed as symbionts of the nematode with which it had coevoluted over a long period.The role of mutualistic symbiosis in the process of pine wilt disease was also discussed.

  13. Influence of gamma irradiation on the metabolic activity of sulfate-reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Agaev, N.M.; Guseinov, M.M.; Smorodin, A.E.

    1985-09-01

    When water is pumped into oil-bearing seams to increase oil production, the microorganisms in the injected water fall into favorable ecological conditions and, quickly adapting, form a biocenosis and begin to actively develop. Among the anaerobic microorganisms, the most hazardous from the corrosion viewpoint are the sulfate-reducing bacteria (SRB), which are the main producers of hydrogen sulfide as the product of anaerobic respiration. This paper reports on the effect of gamma rays on the metabolic study of SRB Desulfovibrio desulfuricans in the nutrient medium Postgate B. The radioactive source used is a /sup 60/CoK-125 unit with a power of 700 rad/sec. The required dose of gamma rays was calculated from the exposure times of samples with the test medium in the radiation zone o the isotope /sup 60/Co. The criterion characterizing the effectiveness of suppression of development of the bacteria is the concentration of biogenic hydrogen sulfide produced, as determined by iodometric titration.

  14. The Pomegranate: Effects on Bacteria and Viruses That Influence Human Health

    Directory of Open Access Journals (Sweden)

    Amy B. Howell

    2013-01-01

    Full Text Available Pomegranates have been known for hundreds of years for their multiple health benefits, including antimicrobial activity. The recent surge in multidrug-resistant bacteria and the possibility of widespread global virus pandemics necessitate the need for additional preventative and therapeutic options to conventional drugs. Research indicates that pomegranates and their extracts may serve as natural alternatives due to their potency against a wide range of bacterial and viral pathogens. Nearly every part of the pomegranate plant has been tested for antimicrobial activities, including the fruit juice, peel, arils, flowers, and bark. Many studies have utilized pomegranate peel with success. There are various phytochemical compounds in pomegranate that have demonstrated antimicrobial activity, but most of the studies have found that ellagic acid and larger hydrolyzable tannins, such as punicalagin, have the highest activities. In some cases the combination of the pomegranate constituents offers the most benefit. The positive clinical results on pomegranate and suppression of oral bacteria are intriguing and worthy of further study. Much of the evidence for pomegranates’ antibacterial and antiviral activities against foodborne pathogens and other infectious disease organisms comes from in vitro cell-based assays, necessitating further confirmation of in vivo efficacy through human clinical trials.

  15. Microbial fuel cells

    International Nuclear Information System (INIS)

    Microbial fuel cells (MFC) are a promising technology for sustainable production of alternative energy and waste treatment. A microbial fuel cell transformation chemical energy in the chemical bonds in organic compounds to electrical energy through catalytic reactions of microorganisms under anaerobic conditions. It has been known for many years that it is possible to generate electricity directly by using bacteria to break down organic substrates. Key words: microbial fuel cells (MFC), biosensor, wastewater treatment

  16. Studies on microbial population in coastal waters - I : Distribution of nitrogen-cycle bacteria in the Kumano Nada and its adjacent areas

    OpenAIRE

    Sugahara, Isao; Hayashi, Koichiro; Kimura, Toshio

    1984-01-01

    The occurrence and distribution of nitrogen-cycle bacteria in the Kumano Nada and its adjacent areas were studied during 1981-1983. Heterotrophic bacteria in the water usually occurred at the level of 100-104/ml.The distribution of heterotrophic bacteria was uneven horizontally as well as vertically.The number of nitrate-reducing bacteria was in the order of 10-1-103 cells/ml, while denitrifying bacteria were in the range from 10-1 to 102cells/ml or sometimes lower than the value. The occurre...

  17. Analysis and modelling of predation on biofilm activated sludge process: Influence on microbial distribution, sludge production and nutrient dosage.

    Science.gov (United States)

    Revilla, Marta; Galán, Berta; Viguri, Javier R

    2016-11-01

    The influence of predation on the biofilm activated sludge (BAS) process is studied using a unified model that incorporates hydrolysis and predation phenomena into the two stages of the BAS system: moving bed biofilm reactor pre-treatment (bacterial-predator stage) and activated sludge (predator stage). The unified model adequately describes the experimental results obtained in a cellulose and viscose full-scale wastewater plant and has been used to evaluate the role and contribution of predator microorganisms towards removal of COD, nutrient requirements, sludge production and microbial distribution. The results indicate that predation is the main factor responsible for the reduction of both nutrient requirements and sludge production. Furthermore, increasing the sludge retention time (SRT) does not influence the total biomass content in the AS reactor of a BAS process in two different industrial wastewater treatments.

  18. A two-species test of the hypothesis that spatial isolation influences microbial diversity in soil.

    Science.gov (United States)

    Treves, D S; Xia, B; Zhou, J; Tiedje, J M

    2003-01-01

    The hypothesis that spatial isolation is a key determinant of microbial community structure in soils was evaluated by examining the competitive dynamics of two species growing on a single resource in a uniform sand matrix under varied moisture content. One species dominated the community under highly connected, saturated treatments, suggesting that these conditions allow competitive interactions to structure the community. As moisture content decreased, however, the less competitive species became established in the community. This effect was most pronounced at a matric water potential of -0.14 MPa where estimates of final population density and species fitness were equal. A second but more closely related species pair exhibited a similar response to decreasing moisture, suggesting that the effects of spatial isolation we observed are not simply a species-pair-specific phenomenon. These findings indicate that spatial isolation, created by low moisture content, plays an important role in structuring soil microbial communities. PMID:12415419

  19. Autochthonous microbial community associated with pine needle forest litterfall influences its degradation under natural environmental conditions.

    Science.gov (United States)

    Mahajan, Rishi; Nikitina, Anna; Litti, Yury; Nozhevnikova, Alla; Goel, Gunjan

    2016-07-01

    The slow natural degradation of chir pine (Pinus roxburghii) needle litterfall and its accumulation on forest floors have been attributed to its lignocellulosic complexities of the biomass. The present study offers a microbiological insight into the role of autochthonous microflora associated with pine needle litterfall in its natural degradation. The denaturing gradient gel electrophoresis (DGGE) fingerprinting indicated actinomycetes (Saccharomonospora sp., Glycomyces sp., Agrococcus sp., Leifsonia sp., Blastocatella sp., and Microbacterium sp.) as a dominant microbial community associated with pine needle litterfall with the absence of fungal decomposers. On exclusion of associated autochthonous microflora from pine litterfall resulted in colonization by decomposer fungi identified as Penicillium chrysogenum and Aspergillus sp., which otherwise failed to colonize the litterfall under natural conditions. The results, therefore, indicated that the autochthonous microbial community of pine needle litterfall (dominated by actinomycetes) obstructs the colonization of litter-degrading fungi and subsequently hinders the overall process of natural degradation of litterfall. PMID:27317052

  20. Study of the Influence of Different Diphenol Compounds on Soil Microbial Activity by Microcalorimetry

    Institute of Scientific and Technical Information of China (English)

    CHEN, Huilun; YAO, Jun; WANG, Fei; GYULA, Zaray

    2009-01-01

    Microcalorimetry was applied to follow the toxic effects caused by different diphenol compounds on microbial activity of Chinese fir soil. The activity of the microorganisms in soil was stimulated by adding 0.3 mL of a nutrient solution containing 2.5 mg of glucose and 2.5 mg of ammonium sulfate and the measurements were performed under a 35% controlled humidity at 28 ℃. Power-time curves recorded on a microcalorimeter were followed by increasing the amount of diphenol compounds, which affected directly the total thermal effects evolved by the microorganisms. The curves showed a synergism on total thermal effect obtained by the addition of 2000 mg·kg~(-1) of resorcinol, causing a consumption of resorcinol by the microorganisms as a new source of nutrients. Above this dose,the total thermal effect decreased exponentially. However, the addition of catechol and hydroquinone caused the total thermal effects to decrease directly. It was concluded that the increase in the diphenol concentration strongly affected the microbial life in this ecosystem. Microcalorimetry appears as a suitable technique to carry out both qualitative and quantitative comparative studies of microbial activity in soil.

  1. Contrasting influence of soil nutrients and microbial community on differently sized basal consumers

    Science.gov (United States)

    Vonk, J. Arie; Mulder, Christian

    2013-07-01

    There is increasing evidence of the coexistence of trophic and environmental constraints belowground. While too often ignored in current literature, the extent to which phosphorus is relevant for soil biota was demonstrated in this study by positive correlations of soil C/P and N/P ratios with all the measured microbial parameters (biomass, density and activity), with the numerical abundance of roundworms (Nematoda) and potworms (Enchytraeidae) from lower trophic levels and with the roundworm biomass. Total worm biomass seems dependent on land use, being in rangelands about twice as high as in croplands, although the relative contribution of potworms remains comparable for both land use types (49 ± 20 % SD versus 45 ± 27 % SD). Besides soil [P], soil type plays an important role in the relative biomass of potworms compared to roundworms. Soil parameters (here pH, C/P and N/P ratios) are better predictors for the abundance and biomass of roundworms than microbial parameters. We also propose a graphical way to visualize the major responses of basal consumers to their microbial drivers.

  2. 137Cs sorption onto Fullers' Earth (calcium montmorillonite) -the influence of sulphate reducing bacteria

    International Nuclear Information System (INIS)

    The influences of Desulfovibrio desulfuricans on the sorption of 137Cs onto Fullers' Earth (Calcium montmorillonite) has been studied using batch sorption methods. Results were expressed as distributions ratios (Rd) and as Freundlich and Dubinin-Radushkevich isotherms. They show that microbes present naturally in the Fullers' Earth did not influence sorption data, however the addition of microbes in the aqueous phase alters the sorption properties in a complex manner. (author)

  3. 渗透压对细菌的影响%Osmosis for the Influence of Bacteria

    Institute of Scientific and Technical Information of China (English)

    陈燕飞

    2012-01-01

    在等渗溶液中,微生物正常生长繁殖;在高渗溶液中,细胞失水收缩,而水分为微生物生理生化反应所必需,失水会抑制其生长繁殖.根据不同盐质量分数下细菌的繁殖情况,可以判断渗透压对细菌的影响.用含不同质量分数NaCl的牛肉膏蛋白胨培养基培养细菌来观察渗透压对细菌的影响,选用的菌种为金黄色葡萄球菌,大肠杆菌,枯草芽孢杆菌.大肠杆菌耐高渗透压的能力较差,在质量分数为3%以下的NaCl溶液中能正常生长,在5%的NaCl溶液中受到抑制;枯草芽孢杆菌和金黄色葡萄球菌有较强的耐盐能力,枯草芽孢杆菌在5%的NaCl溶液中能正常生长,在10%的NaCl溶液中受到抑制,而金黄色葡萄球菌在10%的NaCl溶液中仍能正常生长,在高于10%的NaCl溶液中生长受到抑制.%To study in isotonic solution,the normal growth and reproduction of microorganisms;in hypertonic solution,the cell dehydration shrinkage,and water for the microorganisms necessary for physiological and biochemical reactions,water loss will inhibit the growth and reproduction[1].According to the propagation of bacteria under different salt conditions,can determine the impact of osmotic pressure on the bacteria.NaCl containing different concentrations of beef extract peptone medium for bacteria to observe the impact of osmotic pressure on the bacteria,selected strains Staphylococcus aureus,Escherichia coli,Bacillus subtilis.The ability of E.coli resistant to high osmotic pressure less,at under 3% of NaCl and could grow under 5% NaCl that inhibited;Bacillus subtilis and Staphylococcus aureus have a stronger salt tolerance,Bacillus subtilis,under 5% NaCl and could grow under 10% NaCl was inhibited,while Staphylococcus aureus in 10% NaCl normal despite the growth of above 10% NaCl in growth was inhibited under.

  4. Influence of an oxic settling anoxic system on biomass yield, protozoa and filamentous bacteria.

    Science.gov (United States)

    Rodriguez-Perez, Santiago; Fermoso, Fernando G

    2016-01-01

    An oxic settling anoxic system coupled with an activated sludge process has been studied to reduce sewage sludge production. The reduction of sludge yield, excess sludge production and active biomass yield were 51.7%, 52.9% and 67.1%, respectively, compared with the control system. The oxic reactor of the oxic settling anoxic system, even with a lower active biomass concentration than the oxic reactor of control system, showed a higher metabolic activity in their active biomass. Diversity and crawling ciliates group have been shown as promising bioindicators of active biomass yield reduction. The identification of floc-forming bacteria in the control system suggested that oxic settling anoxic system will improve settling properties compared to a Conventional Activated Sludge process. PMID:26479432

  5. Sugar and Spice Make Bacteria Not Nice: Protein Glycosylation and Its Influence in Pathogenesis.

    Science.gov (United States)

    Valguarnera, Ezequiel; Kinsella, Rachel L; Feldman, Mario F

    2016-08-14

    Protein glycosylation is a post-translational modification that occurs across the whole tree of life. In the recent years, multiple N- and O-glycosylation mechanisms have been identified and characterized in diverse bacterial species, including human pathogens. This review focuses on bacterial protein glycosylation and its impact in pathogenesis. Bacteria carry N- and O-glycosylation systems that are mediated by an oligosaccharyltransferase (OTase). In OTase-dependent glycosylation mechanisms, an oligosaccharide is synthesized on a lipid carrier and subsequently transferred to proteins en bloc by an OTase. Multiple proteins are glycosylated using this mechanism. OTase-independent glycosylation refers to the pathway in which Protein N- and O-glycosyltransferases (PGTases) sequentially add monosaccharides onto the target proteins. This pathway is employed for glycosylation of flagella and autotransporters. By exploiting glycosylation machineries, it is now possible to generate tailor-made glycoconjugates by attaching polysaccharides derived from lipopolysaccharide or capsule biosynthesis onto a protein of choice. These glycoproteins can be used in developing vaccines and diagnostics of bacterial infections. Furthermore, both N- and O-glycosylation systems are promising targets for antibiotic development. Recently, the discovery of GTase toxins produced by bacterial pathogens and secreted into the host cells has greatly expanded. These proteins are a key factor in host-pathogen interactions and are required by certain pathogenic bacteria to establish a successful infection. The exact functions of bacterial glycoproteins in pathogenesis are just starting to emerge. Understanding these roles is key for new opportunities in the prevention of bacterial infections, which is crucial in times when antibiotic resistance continues to increase. PMID:27107636

  6. Influence of Silver nanoparticles on nutrient removal and microbial communities in SBR process after long-term exposure.

    Science.gov (United States)

    Zhang, Zhaohan; Gao, Peng; Li, Moqing; Cheng, Jiaqi; Liu, Wei; Feng, Yujie

    2016-11-01

    The widespread utilization of silver nanoparticles (AgNPs) in industrial and commercial products inevitably raises the release into wastewater that might cause potential negative impacts on sewage treatment system. In this paper, long-term exposure experiments at four levels were conducted to determine whether AgNPs caused adverse impacts on nutrient removals in sequencing batch reactors (SBRs) and changes of microbial community structure. Compared with the control reactor (without AgNPs), carbon, nitrogen and phosphorus removal in presence of 0.1mg/L AgNPs was no difference. However, presence of 1.0 and 10mg/L AgNPs decreased the average removal efficiencies of COD from 95.4% to 85.2% and 68.3%, ammonia nitrogen from 98.8% to 71.2% and 49%, SOP from 97.6% to 75.5% and 54.1%, respectively. It was found that AgNPs could accumulate in sludge with the distribution coefficients of 39.2-114L/g, inhibit the protein and polysaccharide production in EPS, reduce the SOUR of sludge, and greatly increase LDH release from microbial cells. The illumina high-throughput sequencing results indicated that AgNPs concentration changed the structures of bacterial communities, associating with the effects of AgNPs on reactor performance. Sequence analyses showed that Proteobacteria, Bacteroidetes and Acidobacteria were the dominant phyla. It was notable that AgNPs addition reduced the contents of several nitrifying bacteria at genera level in sludge, leading to the lower removal of nitrogen. PMID:27343942

  7. Microbial ecology of the hive and pollination landscape: Bacterial associates from floral nectar, the alimentary tract and stored food of honey bees (Apis mellifera)

    Science.gov (United States)

    Nearly all eukaryotes are host to beneficial or benign bacteria in their gut lumen that are either vertically inherited or acquired from the environment. While the core bacteria of the honey bee gut is becoming evident, the influence of the pollination environment on honey bee-associated microbial p...

  8. Quercetin Influences Quorum Sensing in Food Borne Bacteria: In-Vitro and In-Silico Evidence.

    Directory of Open Access Journals (Sweden)

    Venkadesaperumal Gopu

    Full Text Available Quorum sensing (QS plays a vital role in regulating the virulence factor of many food borne pathogens, which causes severe public health risk. Therefore, interrupting the QS signaling pathway may be an attractive strategy to combat microbial infections. In the current study QS inhibitory activity of quercetin and its anti-biofilm property was assessed against food-borne pathogens using a bio-sensor strain. In addition in-silico techniques like molecular docking and molecular dynamics simulation studies were applied to screen the quercetin's potentiality as QS inhibitor. Quercetin (80 μg/ml showed the significant reduction in QS-dependent phenotypes like violacein production, biofilm formation, exopolysaccharide (EPS production, motility and alginate production in a concentration-dependent manner. Synergistic activity of conventional antibiotics with quercetin enhanced the susceptibility of all tested pathogens. Furthermore, Molecular docking analysis revealed that quercetin binds more rigidly with LasR receptor protein than the signaling compound with docking score of -9.17 Kcal/mol. Molecular dynamics simulation predicted that QS inhibitory activity of quercetin occurs through the conformational changes between the receptor and quercetin complex. Above findings suggest that quercetin can act as a competitive inhibitor for signaling compound towards LasR receptor pathway and can serve as a novel QS-based antibacterial/anti-biofilm drug to manage food-borne pathogens.

  9. [Microbial corrosion of dental alloy].

    Science.gov (United States)

    Li, Lele; Liu, Li

    2004-10-01

    There is a very complicated electrolytical environment in oral cavity with plenty of microorganisms existing there. Various forms of corrosion would develop when metallic prosthesis functions in mouth. One important corrosive form is microbial corrosion. The metabolic products, including organic acid and inorganic acid, will affect the pH of the surface or interface of metallic prosthesis and make a change in composition of the medium, thus influencing the electron-chemical reaction and promoting the development of corrosion. The problem of develpoment of microbial corrosion on dental alloy in the oral environment lies in the primary condition that the bacteria adhere to the surface of alloy and form a relatively independent environment that promotes corrosion. PMID:15553877

  10. Inoculating poultry manure with companion bacteria influences growth and development of black soldier fly (Diptera: Stratiomyidae) larvae.

    Science.gov (United States)

    Yu, Guohui; Cheng, Ping; Chen, Yanhong; Li, Yongjian; Yang, Zihong; Chen, Yuanfeng; Tomberlin, Jeffery K

    2011-02-01

    The growth and development of black soldier fly, Hermetia illucens (L.), larvae fed chicken manure inoculated with bacteria isolated from black soldier fly larvae and associated larval feed was evaluated. Four strains of Bacillus subtilis were evaluated. B. subtilis strains S15, S16, S19, were isolated from the gut of black soldier fly larvae. B. natto strain D1 was isolated from the diet fed to black soldier fly larvae. These bacteria were added individually into nonsterile 200 g fresh hen manure at 10(6) cfu/g and homogenized. Treated manure was then inoculated with 4-d old black soldier fly larvae. Prepupal weight ranged from 0.0606 g in the control to 0.0946 g in manure treated with the S15 strain. Larval survivorship to the prepupal stage in all treatments ranged from 98.00 ± 2.65% to 99.33 ± 1.15%. Prepupal survivorship to the pupal stage ranged from 91.92 ± 1.87% to 97.95 ± 1.03%. Adult emergence from the pupal stage did not significantly (P black soldier fly larvae influences the growth and development of conspecific larvae feeding on the manure. PMID:22182608

  11. The production-influencing factors of extracellular polysacchadde(EPS) from a Strain of lactic acid bacteria and EPS extraction

    Institute of Scientific and Technical Information of China (English)

    CHEN Ying; SUN Liping; ZENG Yong; WANG Lei; AN Liguo

    2006-01-01

    The influencing factors of extracellular polysaccharide(EPS)produced from a strain of lactic acid bacteria(LAB L15)were studied by using the phenol-H2SO4 method.It was demonstrated that the strain produced EPS at the most amount when it was incubated for 40-48 h and when the pH value was 4 under 30℃.Glucose was the most suitable carbon source for LAB-producing EPS.The rough EPS was obtained from L15 culture after centrifugation,dialysis,deprotein,decoloration,and ethanol-precipitation.The sample was at least composed of two polysaccharides mat were completely different in molecular weight and the amount.The purified EPS was passed through the SephadexG-200 colunm and it showed that it was a sample purified by thin layer chromatography.

  12. Impact of a Recombinant Biocontrol Bacterium, Pseudomonas fluorescens pc78, on Microbial Community in Tomato Rhizosphere

    Directory of Open Access Journals (Sweden)

    Hyun Gi Kong

    2016-04-01

    Full Text Available Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer.

  13. Impact of a Recombinant Biocontrol Bacterium, Pseudomonas fluorescens pc78, on Microbial Community in Tomato Rhizosphere.

    Science.gov (United States)

    Kong, Hyun Gi; Kim, Nam Hee; Lee, Seung Yeup; Lee, Seon-Woo

    2016-04-01

    Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer. PMID:27147933

  14. Habitat influences on diversity of bacteria found on German cockroach in Beijing

    Institute of Scientific and Technical Information of China (English)

    FU Xue; YE Lefu; GE Feng

    2009-01-01

    Cockroaches are worldwide indoor pests carrying microorganisms of medical importance.German cockroaches (Blattella germanica) were sampled in five habitats (hospital, restaurant, office home, and market) in Beijing, and the bacteria were isolated from their external surface and alimentary tract and identified using a Biolog identification system.Cockroach densities significantly differed among habitats (market > home > office > restaurant > hospital).However, no significant differences in bacterial abundance carried by individual German cockroaches (of either sex) were found among habitats.The bacterial abundance in the gut was significantly higher than that on the surface.There were no significant differences in bacterial species richness observed among habitats, sex, carrying position or their interaction.Cluster analysis showed that cockroach densities and bacterial abundance found in the market differed significantly from the other four habitats.The bacterial diversity was not significantly reduced in sensitive facilities such as hospital and restaurant, even though pesticide and bactericide were more frequently applied there.The implications of these findings were discussed in this article.

  15. Influence of diet and microbial activity in the digestive tract on digestibility, and nitrogen and energy metabolism in rats and pigs

    DEFF Research Database (Denmark)

    Eggum, B O; Thorbek, G; Beames, R M;

    1982-01-01

    1. Balance trials with respiration measurements were performed with twelve rats and twelve pigs given either low- or high-crude-fibre diets. There were six collection periods with the rats over a live-weight range of 86-264 g and three collection periods with the pigs over a live-weight range of 30......-55 kg. Measurements were made on the influence of microbial activity in the digestive tract on digestibility and nitrogen and energy metabolism. Dietary inclusion of the antibiotic Nebacitin was the method used to reduce the microbial population. 2. The microbial activity in the hind-gut (mumol ATP....../g air-dry contents) of antibiotic-treated rats was reduced to approximately one-tenth of that of untreated rats. 3. Live-weight gain was not significantly affected in either species by a reduction in the microbial activity, in spite of a reduction in dry matter digestibility in animals with reduced...

  16. Factors Influencing the Accumulation and Subsurface Transport of Fecal Indicator Bacteria near the Shoreline at Freshwater Beaches

    Science.gov (United States)

    Wu, M. Z.; O'Carroll, D. M.; Vogel, L. J.; Robinson, C. E.

    2015-12-01

    Beach sand near the shoreline acts as a reservoir for fecal contaminants with fecal indicator bacteria (FIB) often orders of magnitude higher than in adjacent surface waters. This reservoir poses a human health risk and can also act as an important non-point contamination source for surface waters. Beach water quality advisories or closures can be issued when FIB (Escherichia coli (E. coli), enterococci (ENT)) concentrations are elevated in the surface water. The factors controlling the transport and accumulation of FIB in the foreshore sand are not well understood, though this is required to manage and mitigate this source. Multiple sources may contribute to the accumulation of FIB in sand, with recent studies suggesting that the continuous influx of surface water across the sediment-water interface may be a dominant source at many beaches.The study objective was to develop understanding of the physical processes controlling the accumulation and transport of FIB in beach sand. Field measurements were combined with numerical modelling to evaluate the role of low-energy lapping waves in delivering FIB to the saturated foreshore sand at freshwater beaches. E. coli and ENT were measured at two beaches in Ontario, Canada at depths of up to 1 and 2 m, respectively, below the water table. A numerical model simulating wave-induced groundwater recirculations coupled with microbial transport (using colloid filtration theory) showed that the different FIB distributions measured at the two beaches was due mainly to the different beach slope and terrestrial groundwater flow. The model was applied to assess the impact of beach, wave and bacterial parameters on FIB accumulation. The infiltration zone width, average infiltration velocity and infiltration rate were shown to ultimately control the amount and spatial distribution of FIB in the sand. The study findings are important in understanding factors controlling the transport of FIB at the sediment-water interface of

  17. Can transgenic maize affect soil microbial communities?

    Science.gov (United States)

    Mulder, Christian; Wouterse, Marja; Raubuch, Markus; Roelofs, Willem; Rutgers, Michiel

    2006-09-29

    The aim of the experiment was to determine if temporal variations of belowground activity reflect the influence of the Cry1Ab protein from transgenic maize on soil bacteria and, hence, on a regulatory change of the microbial community (ability to metabolize sources belonging to different chemical guilds) and/or a change in numerical abundance of their cells. Litter placement is known for its strong influence on the soil decomposer communities. The effects of the addition of crop residues on respiration and catabolic activities of the bacterial community were examined in microcosm experiments. Four cultivars of Zea mays L. of two different isolines (each one including the conventional crop and its Bacillus thuringiensis cultivar) and one control of bulk soil were included in the experimental design. The growth models suggest a dichotomy between soils amended with either conventional or transgenic maize residues. The Cry1Ab protein appeared to influence the composition of the microbial community. The highly enhanced soil respiration observed during the first 72 h after the addition of Bt-maize residues can be interpreted as being related to the presence of the transgenic crop residues. This result was confirmed by agar plate counting, as the averages of the colony-forming units of soils in conventional treatments were about one-third of those treated with transgenic straw. Furthermore, the addition of Bt-maize appeared to induce increased microbial consumption of carbohydrates in BIOLOG EcoPlates. Three weeks after the addition of maize residues to the soils, no differences between the consumption rate of specific chemical guilds by bacteria in soils amended with transgenic maize and bacteria in soils amended with conventional maize were detectable. Reaped crop residues, comparable to post-harvest maize straw (a common practice in current agriculture), rapidly influence the soil bacterial cells at a functional level. Overall, these data support the existence of short

  18. Influence of microbial and synthetic surfactant on the biodegradation of atrazine.

    Science.gov (United States)

    Singh, Anil Kumar; Cameotra, Swaranjit Singh

    2014-02-01

    The present study reports the effect of surfactants (rhamnolipids and triton X-100) on biodegradation of atrazine herbicide by strain A6, belonging to the genus Acinetobacter. The strain A6 was able to degrade nearly 80 % of the 250-ppm atrazine after 6 days of growth. The bacterium degraded atrazine by de-alkylation process. Bacterial cell surface hydrophobicity as well as atrazine solubility increased in the presence of surfactant. However, addition of surfactant to the mineral salt media reduced the rate and extent of atrazine degradation by decreasing the bioavailability of herbicide. On the contrary, addition of surfactant to atrazine-contaminated soil increased the rate and extent of biodegradation by increasing the bioavailability of herbicide. As compared to triton X-100, rhamnolipids were more efficient in enhancing microbial degradation of atrazine as a significant amount of atrazine was removed from the soil by rhamnolipids. Surfactants added for the purpose of hastening microbial degradation may have an unintended inhibitory effect on herbicide degradation depending upon contiguous condition, thus highlighting the fact that surfactant must be judiciously used in bioremediation of herbicides.

  19. The Influence of Loading Rate and Variable Temperatures on Microbial Communities in Anaerobic Digesters

    Directory of Open Access Journals (Sweden)

    Richard J. Ciotola

    2014-02-01

    Full Text Available The relationship between seasonal temperatures, organic loading rate (OLR and the structure of archaeal communities in anaerobic digesters was investigated. Previous studies have often assessed archaeal community structure at fixed temperatures and constant OLRs, or at variable temperatures not characteristic of temperate climates. The goal of this study was to determine the maximum OLR that would maintain a balanced microbial ecosystem during operation in a variable temperature range expected in a temperate climate (27–10 °C. Four-liter laboratory digesters were operated in a semi-continuous mode using dairy cow manure as the feedstock. At OLRs of 1.8 and 0.8 kg VS/m3·day the digesters soured (pH < 6.5 as a result of a decrease in temperature. The structure of the archaeal community in the sour digesters became increasingly similar to the manure feedstock with gains in the relative abundance of hydrogenotrophic methanogens. At an OLR of 0.3 kg VS/m3·day the digesters did not sour, but the archaeal community was primarily hydrogenotrophic methanogens. Recommendations for operating an ambient temperature digester year round in a temperate climate are to reduce the OLR to at least 0.3 kg VS/m3·day in colder temperatures to prevent a shift to the microbial community associated with the sour digesters.

  20. Microbial degradation and its influence on components of coalbed gases in Enhong syncline, China

    Institute of Scientific and Technical Information of China (English)

    Lan Fengjuan; Qin Yong; Li Ming; Tang Yonghong; Guo Chen; Zhang Fei

    2013-01-01

    Coalbed gases (CBG) in Enhong syncline are characterized by high concentration of C2+ (C2-5),with the highest content of ethane over 30%.However,the concentrations of C2+ are not evenly distributed in the syncline.Based on the analysis of δ13C1,δ13C2,δ13C3,δ13CO2,δDcH4 of CBG and their origin diagrams in the normal and abnormal areas,this research shows that gases in both areas are thermogenic gases and the reason for the uneven distribution of C2+ is that the microbial degradation action on gases is stronger in the normal area than in the abnormal area.The secondary biologic gases in the normal area are mainly characterized by that the carbon isotopes become obviously lighter in methane and become heavier in ethane,whereas the molecular and isotopic compositions of CO2 change little.These features indicate that the secondary biologic gases are mainly generated by the microbial degradation of C2+,not generated by the reduction of CO2.The degradation process is selective to make the residual ethane being enriched in 13C and the generated methane rich in 12C.

  1. Influence of Purple Sulfur Bacteria on the biogeochemistry of Carbon and Sulfur Isotopes in Crystal Lake, OH

    Science.gov (United States)

    Meyer, A.; Nichols, D. L.; Cheng, S.

    2013-12-01

    Crystal Lakes are a series of four interconnected mesotrophic, moulin-induced glacial lakes in west-central Ohio. The study site, Main Lake (a.k.a. Crystal Lake), is the largest and deepest lake among them. It is about 5 ha with a maximum depth of 11.9 meters and a mean depth of 3.8 meters. Thermal stratification develops during the warmer months. Photosynthesis, which preferentially uptakes lighter isotopes, is the primary pathway for carbon and sulfur isotope fractionation in natural waters. Photosynthesizers present at Crystal Lake include green algae, diatoms, cyanobacteria, and purple sulfur bacteria (PSB). Phytoplankton growth is limited by nutrient availability, influencing the extent of fractionation. Purple sulfur bacteria (PSB) utilize sulfide as an electron donor instead of water. The layer of concentrated PSB population exists between oxic and anoxic water in lakes where sufficient light and sulfide are present. These bacteria impact the levels of several sulfur compounds and isotopic composition within lake systems by oxidizing sulfide to sulfate. Field parameters collected in warmer months show turbidity and chlorophyll peaks around 6 m with variations caused by temperature, light, and nutrient availability. The dissolved oxygen minimum and the redox and sulfate maxima generally correspond with the turbidity and chlorophyll peaks, indicating the presence of a PSB layer. This layer occurs at the boundary between the metalimnion and hypolimnion. Sulfide concentrations increased from a maximum of 0.02 mg/L in May to a maximum of 9.25 mg/L in August. In May sulfide was only found at 10.4 m and below while in August it was present at 6 m and below. Sulfate values remain relatively constant with a maximum at the layer of PSB, then decline with depth where Sulfide is abundant. δ13C-DIC values peak at 6 m corresponding with the layer of PSB. This peak may be due to the influence of PSB on carbon isotope fractionation. The carbon isotope composition of

  2. Influence of co-substrate on textile wastewater treatment and microbial community changes in the anaerobic biological sulfate reduction process.

    Science.gov (United States)

    Rasool, Kashif; Mahmoud, Khaled A; Lee, Dae Sung

    2015-12-15

    This study investigated the anaerobic treatment of sulfate-rich synthetic textile wastewater in three sulfidogenic sequential batch reactors (SBRs). The experimental protocol was designed to examine the effect of three different co-substrates (lactate, glucose, and ethanol) and their concentrations on wastewater treatment performance. Sulfate reduction and dye degradation were improved when lactate and ethanol were used as electron donors, as compared with glucose. Moreover, under co-substrate limited concentrations, color, sulfate, and chemical oxygen demand (COD) removal efficiencies were declined. By reducing co-substrate COD gradually from 3000 to 500 mg/L, color removal efficiencies were decreased from 98.23% to 78.46%, 63.37%, and 69.10%, whereas, sulfate removal efficiencies were decreased from 98.42%, 82.35%, and 87.0%, to 30.27%, 21.50%, and 10.13%, for lactate, glucose, and ethanol fed reactors, respectively. Fourier transform infrared spectroscopy (FTIR) and total aromatic amine analysis revealed lactate to be a potential co-substrate for further biodegradation of intermediate metabolites formed after dye degradation. Pyrosequencing analysis showed that microbial community structure was significantly affected by the co-substrate. The reactor with lactate as co-substrate showed the highest relative abundance of sulfate reducing bacteria (SRBs), followed by ethanol, whereas the glucose-fed reactor showed the lowest relative abundance of SRB. PMID:26241771

  3. Substrate-induced changes in microbial community-level physiological profiles and their application to discriminate soil microbial communities

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian; XIE Huijun; ZHUANG Xuliang; ZHUANG Guoqiang; BAI Zhihui; ZHANG Hongxun

    2008-01-01

    The addition of simple substrates could affect the microbial respiration in soils.This substrate-induced respiration is widely used to estimate the soil microbial biomass,but little attention has been paid to its influence on the changes of community-level physiological profiles.In this study,the process of microbial communities responding to the added substrate using sole-carbon-source utilization (BIOLOG) was investigated.BIOLOG is biased toward fast-growing bacteria;this advantage Was taken to detect the prompt response of the active microbial communities to the added substrate.Four soil samples from agricultural fields adjacent to heavy metal mines were amended with L-arginine,citric acid,or D-glucose.Substrate amendments could,generally,not only increase the metabolic activity of the microbial communities,but also change the metabolic diverse patterns compared with no-substrate contr01.By tracking the process,it was found that the variance between substrate-induced treatment and control fluctuated greatly during the incubation course,and the influences of these three substrates were difierent.In addition,the application of these induced changes to discriminate soil microbial communities was tested.T1le distance among all samples was greatly increased.which further showed the functional variance among microbial communities in soils.This Can be very useful in the discrimination of microbial communities eveB with high similarity.

  4. Culex pipiens Development Is Greatly Influenced by Native Bacteria and Exogenous Yeast

    Science.gov (United States)

    Díaz-Nieto, Leonardo M.; D´Alessio, Cecilia

    2016-01-01

    Culex pipiens is the most cosmopolitan mosquito of the Pipiens Assemblage. By studying the nature of interactions between this species and microorganisms common to its breeding environment we can unravel important pitfalls encountered during development. We tested the survival rate of larval stages, pupae and adults of a Cx. pipiens colony exposed to a variety of microorganisms in laboratory conditions and assessed the transmission to offspring (F1) by those organisms that secured development up to adulthood. Three complementary experiments were designed to: 1) explore the nutritional value of yeasts and other microorganisms during Cx. pipiens development; 2) elucidate the transstadial transmission of yeast to the host offspring; and 3) to examine the relevance of all these microorganisms in female choice for oviposition-substratum. The yeast Saccharomyces cerevisiae proved to be the most nutritional diet, but despite showing the highest survival rates, vertical transmission to F1 was never confirmed. In addition, during the oviposition trials, none of the gravid females was attracted to the yeast substratum. Notably, the two native bacterial strains, Klebsiella sp. and Aeromonas sp., were the preferred oviposition media, the same two bacteria that managed to feed neonates until molting into 2nd instar larvae. Our results not only suggest that Klebsiella sp. or Aeromonas sp. serve as attractants for oviposition habitat selection, but also nurture the most fragile instar, L1, to assure molting into a more resilient stage, L2, while yeast proves to be the most supportive diet for completing development. These experiments unearthed survival traits that might be considered in the future development of strategies of Cx. pipiens control. These studies can be extended to other members of the Pipiens Assemblage. PMID:27055276

  5. The use of microbial-earthworm ecofilters for wastewater treatment with special attention to influencing factors in performance: A review.

    Science.gov (United States)

    Jiang, Luhua; Liu, Yunguo; Hu, Xinjiang; Zeng, Guangming; Wang, Hui; Zhou, Lu; Tan, Xiaofei; Huang, Binyan; Liu, Shaobo; Liu, Simian

    2016-01-01

    With the unique advantages of lower operational and maintenance cost, the use of microbial-earthworm ecofilters (MEEs) for the wastewater treatment has been increasing rapidly in the recent years. This paper provided an overview of the research activities on the use of MEEs for removing pollutants from various wastewater throughout the world. However, the long-term effective treatment performance and sustainable operation of this system still remain a challenge since the treatment performance would be affected by design parameters, operational conditions, and environmental factors. In order to promote the treatment performance, therefore, this paper also provided and summarized the influencing factors of pollutants removal in MEEs. The design parameters and operational conditions of MEEs include earthworm species and load, filter media type, hydraulic loading rate, nutrient load, packing bed height, chemical factors and temperature. Lastly, this review highlighted the further research on these issues to improve performance and sustainability of MEEs. PMID:26611806

  6. The influence of whey protein concentrate on growth and survival of probiotic bacteria in whey

    OpenAIRE

    Ljubica Tratnik; Rajka Božanić; Bojan Matijević; Irena Jeličić

    2008-01-01

    This research examines the influence of whey protein concentrate addition (WPC) on growth and activity of probiotic species Lactobacilus acidophilus La-5 and Bifidobacterium animalis subsp. lactis BB-12 in sweet reconstituted whey and their survival during 28 days of fermented whey cold storage (4 °C). The fermentation of whey at 37º C with and without 1.5 and 3% of WPC addition has been observed. Fermentation of whey with Lactobacillus acidophilus La-5 to which 3% WPC was added, was about an...

  7. Influence of the fuel and dosage on the performance of double-compartment microbial fuel cells.

    Science.gov (United States)

    Asensio, Y; Fernandez-Marchante, C M; Lobato, J; Cañizares, P; Rodrigo, M A

    2016-08-01

    This manuscript focuses on the evaluation of the use of different types and dosages of fuels in the performance of double-compartment microbial fuel cell equipped with carbon felt electrodes and cationic membrane. Five types of fuels (ethanol, glycerol, acetate, propionate and fructose) have been tested for the same organic load (5,000 mg L(-1) measured as COD) and for one of them (acetate), the range of dosages between 500 and 20,000 mg L(-1) of COD was also studied. Results demonstrate that production of electricity depends strongly on the fuel used. Carboxylic acids are much more efficient than alcohols or fructose for the same organic load and within the range 500-5,000 mg L(-1) of acetate the production of electricity increases linearly with the amount of acetate fed but over these concentrations a change in the population composition may explain a worse performance.

  8. Influence of processed sugarcane bagasse on the microbial, nutritional, rheological and quality characteristics of biscuits.

    Science.gov (United States)

    Sangeetha, A V; Mahadevamma, S; Begum, Khyrunnisa; Sudha, M L

    2011-08-01

    Sugarcane bagasse, a dietary fiber-rich by-product of the sugar industry (70-75%) and having negligible protein and fat content, was treated with acid, alkali and steaming to reduce the microbial load. Steaming was effective in making the bagasse microbiologically safe. The processed bagasse (5-15%) was used in the rheological studies and in the preparation of soft dough biscuits. Glucose (hexose), arabinose and xylose (pentose) were present, whereas rhamnose, mannose and galctose were not traced in all of the bagasse samples. Farinograph characteristics of wheat flour-bagasse blends showed that the mixing profile weakened with addition of bagasse. Processed bagasse also affected the pasting characteristics indicating starch dilution on incorporation of bagasse, as indicated by sensory characteristics. Biscuits prepared from steamed bagasse (10%) along with additives were highly acceptable. Results indicated that high-fiber biscuits can be prepared by replacing wheat flour with steamed bagasse at a 10% level.

  9. Influence of the fuel and dosage on the performance of double-compartment microbial fuel cells.

    Science.gov (United States)

    Asensio, Y; Fernandez-Marchante, C M; Lobato, J; Cañizares, P; Rodrigo, M A

    2016-08-01

    This manuscript focuses on the evaluation of the use of different types and dosages of fuels in the performance of double-compartment microbial fuel cell equipped with carbon felt electrodes and cationic membrane. Five types of fuels (ethanol, glycerol, acetate, propionate and fructose) have been tested for the same organic load (5,000 mg L(-1) measured as COD) and for one of them (acetate), the range of dosages between 500 and 20,000 mg L(-1) of COD was also studied. Results demonstrate that production of electricity depends strongly on the fuel used. Carboxylic acids are much more efficient than alcohols or fructose for the same organic load and within the range 500-5,000 mg L(-1) of acetate the production of electricity increases linearly with the amount of acetate fed but over these concentrations a change in the population composition may explain a worse performance. PMID:27130968

  10. Solute concentrations influence microbial methanogenesis in coal-bearing strata of the Cherokee basin, USA

    Directory of Open Access Journals (Sweden)

    Matthew F Kirk

    2015-11-01

    Full Text Available Microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4-1.1 m coalbeds with marginal thermal maturities (0.5-0.7 %Ro that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na-Cl type with total dissolved solids (TDS content ranging from 34.9 to 91.3 g L-1. Gas dryness values [C1/(C2+C3] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65‰ and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%, and few archaeal sequences (avg 4.2% were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast, bacterial diversity more strongly correlates with location than solute

  11. Microbial symbionts in insects influence down-regulation of defense genes in maize.

    Directory of Open Access Journals (Sweden)

    Kelli L Barr

    Full Text Available Diabrotica virgifera virgifera larvae are root-feeding insects and significant pests to maize in North America and Europe. Little is known regarding how plants respond to insect attack of roots, thus complicating the selection for plant defense targets. Diabrotica virgifera virgifera is the most successful species in its genus and is the only Diabrotica beetle harboring an almost species-wide Wolbachia infection. Diabrotica virgifera virgifera are infected with Wolbachia and the typical gut flora found in soil-living, phytophagous insects. Diabrotica virgifera virgifera larvae cannot be reared aseptically and thus, it is not possible to observe the response of maize to effects of insect gut flora or other transient microbes. Because Wolbachia are heritable, it is possible to investigate whether Wolbachia infection affects the regulation of maize defenses. To answer if the success of Diabrotica virgifera virgifera is the result of microbial infection, Diabrotica virgifera virgifera were treated with antibiotics to eliminate Wolbachia and a microarray experiment was performed. Direct comparisons made between the response of maize root tissue to the feeding of antibiotic treated and untreated Diabrotica virgifera virgifera show down-regulation of plant defenses in the untreated insects compared to the antibiotic treated and control treatments. Results were confirmed via QRT-PCR. Biological and behavioral assays indicate that microbes have integrated into Diabrotica virgifera virgifera physiology without inducing negative effects and that antibiotic treatment did not affect the behavior or biology of the insect. The expression data and suggest that the pressure of microbes, which are most likely Wolbachia, mediate the down-regulation of many maize defenses via their insect hosts. This is the first report of a potential link between a microbial symbiont of an insect and a silencing effect in the insect host plant. This is also the first expression

  12. Solute Concentrations Influence Microbial Methanogenesis in Coal-bearing Strata of the Cherokee Basin, USA.

    Science.gov (United States)

    Kirk, Matthew F; Wilson, Brien H; Marquart, Kyle A; Zeglin, Lydia H; Vinson, David S; Flynn, Theodore M

    2015-01-01

    Microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4-1.1 m) coalbeds with marginal thermal maturities (0.5-0.7% R o ) that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na-Cl type with total dissolved solids (TDS) content ranging from 34.9 to 91.3 g L(-1). Gas dryness values [C1/(C2 + C3)] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65 and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%), and few archaeal sequences (avg 4.2%) were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast, bacterial diversity more strongly correlates with location than solute content

  13. Factors influencing the microbial composition of metalworking fluids and potential implications for machine operator's lung.

    Science.gov (United States)

    Murat, Jean-Benjamin; Grenouillet, Frédéric; Reboux, Gabriel; Penven, Emmanuelle; Batchili, Adam; Dalphin, Jean-Charles; Thaon, Isabelle; Millon, Laurence

    2012-01-01

    Hypersensitivity pneumonitis, also known as "machine operator's lung" (MOL), has been related to microorganisms growing in metalworking fluids (MWFs), especially Mycobacterium immunogenum. We aimed to (i) describe the microbiological contamination of MWFs and (ii) look for chemical, physical, and environmental parameters associated with variations in microbiological profiles. We microbiologically analyzed 180 MWF samples from nonautomotive plants (e.g., screw-machining or metal-cutting plants) in the Franche-Comté region in eastern France and 165 samples from three French automotive plants in which cases of MOL had been proven. Our results revealed two types of microbial biomes: the first was from the nonautomotive industry, showed predominantly Gram-negative rods (GNR), and was associated with a low risk of MOL, and the second came from the automotive industry that was affected by cases of MOL and showed predominantly Gram-positive rods (GPR). Traces of M. immunogenum were sporadically detected in the first type, while it was highly prevalent in the automotive sector, with up to 38% of samples testing positive. The use of chromium, nickel, or iron was associated with growth of Gram-negative rods; conversely, growth of Gram-positive rods was associated with the absence of these metals. Synthetic MWFs were more frequently sterile than emulsions. Vegetable oil-based emulsions were associated with GNR, while mineral ones were associated with GPR. Our results suggest that metal types and the nature of MWF play a part in MWF contamination, and this work shall be followed by further in vitro simulation experiments on the kinetics of microbial populations, focusing on the phenomena of inhibition and synergy. PMID:22057869

  14. Redox gradients in distribution systems influence water quality, corrosion, and microbial ecology.

    Science.gov (United States)

    Masters, Sheldon; Wang, Hong; Pruden, Amy; Edwards, Marc A

    2015-01-01

    Simulated distribution systems (SDSs) defined the interplay between disinfectant type (free chlorine and chloramines), water age (1-10.2 days), and pipe material (PVC, iron and cement surfaces) on water chemistry, redox zones and infrastructure degradation. Redox gradients developed as a function of water age and pipe material affected the quality of water consumers would receive. Free chlorine was most stable in the presence of PVC while chloramine was most stable in the presence of cement. At a 3.6 day water age the residual in the chlorinated PVC SDS was more than 3.5 times higher than in the chlorinated iron or cement systems. In contrast, the residual in the chloraminated cement SDS was more than 10 times greater than in the chloraminated iron or PVC systems. Near the point of entry to the SDSs where disinfectant residuals were present, free chlorine tended to cause as much as 4 times more iron corrosion when compared to chloramines. Facultative denitrifying bacteria were ubiquitous, and caused complete loss of nitrogen at distal points in systems with iron, and these bacteria co-occurred with very severe pitting attack (1.6-1.9 mm/year) at high water age. PMID:25462724

  15. Influence of Sulfate-Reducing Bacteria on the Corrosion Behavior of High Strength Steel EQ70 under Cathodic Polarization

    Science.gov (United States)

    Guan, Fang; Zhai, Xiaofan; Duan, Jizhou; Zhang, Meixia; Hou, Baorong

    2016-01-01

    Certain species of sulfate-reducing bacteria (SRB) use cathodes as electron donors for metabolism, and this electron transfer process may influence the proper protection potential choice for structures. The interaction between SRB and polarized electrodes had been the focus of numerous investigations. In this paper, the impact of cathodic protection (CP) on Desulfovibrio caledoniens metabolic activity and its influence on highs trength steel EQ70 were studied by bacterial analyses and electrochemical measurements. The results showed that EQ70 under -0.85 VSCE CP had a higher corrosion rate than that without CP, while EQ70 with -1.05 VSCE had a lower corrosion rate. The enhanced SRB metabolic activity at -0.85 VSCE was most probably caused by the direct electron transfer from the electrode polarized at -0.85 VSCE. This direct electron transfer pathway was unavailable in -1.05 VSCE. In addition, the application of cathodic protection led to the transformation of sulfide rusts into carbonates rusts. These observations have been employed to provide updated recommendations for the optimum CP potential for steel structures in the presence of SRB. PMID:27603928

  16. Adhesion of Pathogenic Bacteria to Food Contact Surfaces: Influence of pH of Culture

    Directory of Open Access Journals (Sweden)

    Akier Assanta Mafu

    2011-01-01

    Full Text Available The adhesion of Aeromonas hydrophila, Escherichia coli O157:H7, Salmonella Enteritidis, and Staphylococcus aureus to hydrophobic and hydrophilic surfaces in cultures with different pHs (6, 7, and 8 was studied. The results indicated that the type of material had no effect on the attachment capacity of microorganisms, while environmental pH influenced the adhesion of A. hydrophila, E. coli, and S. aureus to both solid substrates. The attachment of S. Enteritidis (P>.05 was not affected by the type of substrate or the culture pH, whereas E. coli displayed the weakest affinity for both polystyrene and glass surfaces. No correlation was established between the physicochemical properties of the materials, or the bacterial and the rate of bacterial adhesion, except for S. aureus. Photomicrographs have shown that surfaces were contaminated by small clusters of S. Enteritidis while S. aureus invaded the food contact surfaces in the form of small chains or cell aggregates.

  17. Bacillus anthracis-like bacteria and other B. cereus group members in a microbial community within the International Space Station: a challenge for rapid and easy molecular detection of virulent B. anthracis.

    Directory of Open Access Journals (Sweden)

    Sandra P van Tongeren

    Full Text Available For some microbial species, such as Bacillus anthracis, the etiologic agent of the disease anthrax, correct detection and identification by molecular methods can be problematic. The detection of virulent B. anthracis is challenging due to multiple virulence markers that need to be present in order for B. anthracis to be virulent and its close relationship to Bacillus cereus and other members of the B. cereus group. This is especially the case in environments where build-up of Bacillus spores can occur and several representatives of the B. cereus group may be present, which increases the chance for false-positives. In this study we show the presence of B. anthracis-like bacteria and other members of the B. cereus group in a microbial community within the human environment of the International Space Station and their preliminary identification by using conventional culturing as well as molecular techniques including 16S rDNA sequencing, PCR and real-time PCR. Our study shows that when monitoring the microbial hygiene in a given human environment, health risk assessment is troublesome in the case of virulent B. anthracis, especially if this should be done with rapid, easy to apply and on-site molecular methods.

  18. Bacillus anthracis-like bacteria and other B. cereus group members in a microbial community within the International Space Station: a challenge for rapid and easy molecular detection of virulent B. anthracis.

    Science.gov (United States)

    van Tongeren, Sandra P; Roest, Hendrik I J; Degener, John E; Harmsen, Hermie J M

    2014-01-01

    For some microbial species, such as Bacillus anthracis, the etiologic agent of the disease anthrax, correct detection and identification by molecular methods can be problematic. The detection of virulent B. anthracis is challenging due to multiple virulence markers that need to be present in order for B. anthracis to be virulent and its close relationship to Bacillus cereus and other members of the B. cereus group. This is especially the case in environments where build-up of Bacillus spores can occur and several representatives of the B. cereus group may be present, which increases the chance for false-positives. In this study we show the presence of B. anthracis-like bacteria and other members of the B. cereus group in a microbial community within the human environment of the International Space Station and their preliminary identification by using conventional culturing as well as molecular techniques including 16S rDNA sequencing, PCR and real-time PCR. Our study shows that when monitoring the microbial hygiene in a given human environment, health risk assessment is troublesome in the case of virulent B. anthracis, especially if this should be done with rapid, easy to apply and on-site molecular methods.

  19. Petroleum hydrocarbon biodegradation and microbial responses under seasonal freeze-thaw conditions

    Energy Technology Data Exchange (ETDEWEB)

    Chang, W.; Ghoshal, S. [McGill Univ., Montreal, PQ (Canada). Dept. of Civil Engineering and Applied Mechanics; Klemm, S.; Whyte, L. [McGill Univ., Montreal, PQ (Canada). Dept. of Natural Resource Sciences; Simon, P. [Qikiqtaaluk Environmental Inc., Montreal, PQ (Canada)

    2010-07-01

    Seasonal freeze-thaw temperatures influence the metabolic functions of indigenous cold-adapted bacteria. Quantitative assessments of petroleum hydrocarbon biodegradation and microbial community changes under seasonal freeze-thaw temperatures were investigated in this study. Semi- and non-volatile hydrocarbon fractions were measured and microbial community compositions were characterized in a series of controlled biodegradation experiments conducted in a cold room where the seasonal freeze-thaw temperatures of a sub-Arctic site at Resolution Island were simulated. Results of the experiments demonstrated that the seasonal freezing rate did not stop microbial activity. The growth of viable microbial populations was observed in a nutrient-amended soil tank. Microbial respiration was observed during the semi-frozen soil phase where unfrozen water and pore ice co-existed in the soils. Respiration activity was accelerated due to the rapid increases of soil temperature that occurred in early summer. Microbial community shifts were observed during the freezing and thawing phase.

  20. The influence of soil organic carbon on interactions between microbial parameters and metal concentrations at a long-term contaminated site

    Energy Technology Data Exchange (ETDEWEB)

    Muhlbachova, G. [Crop Research Institute, Drnovska 507, 161 06 Prague 6, Ruzyne (Czech Republic); Sagova-Mareckova, M., E-mail: sagova@vurv.cz [Crop Research Institute, Drnovska 507, 161 06 Prague 6, Ruzyne (Czech Republic); Omelka, M. [Charles University, Faculty of Mathematics and Physics, Dept. of Probability and Mathematical Statistics, Prague 8, Karlin (Czech Republic); Szakova, J.; Tlustos, P. [Czech University of Life Sciences, Department of Agroenvironmental Chemistry and Plant Nutrition, Prague 6, Suchdol (Czech Republic)

    2015-01-01

    The effects of lead, zinc, cadmium, arsenic and copper deposits on soil microbial parameters were investigated at a site exposed to contamination for over 200 years. Soil samples were collected in triplicates at 121 sites differing in contamination and soil organic carbon (SOC). Microbial biomass, respiration, dehydrogenase activity and metabolic quotient were determined and correlated with total and extractable metal concentrations in soil. The goal was to analyze complex interactions between toxic metals and microbial parameters by assessing the effect of soil organic carbon in the relationships. The effect of SOC was significant in all interactions and changed the correlations between microbial parameters and metal fractions from negative to positive. In some cases, the effect of SOC was combined with that of clay and soil pH. In the final analysis, dehydrogenase activity was negatively correlated to total metal concentrations and acetic acid extractable metals, respiration and metabolic quotient were to ammonium nitrate extractable metals. Dehydrogenase activity was the most sensitive microbial parameter correlating most frequently with contamination. Total and extractable zinc was most often correlated with microbial parameters. The large data set enabled robust explanation of discrepancies in organic matter functioning occurring frequently in analyzing of contaminated soil processes. - Highlights: • Soil organic carbon affected all interactions between metals and microorganisms. • Soil organic carbon adjustment changed correlations from positive to negative. • Ammonium nitrate extractable metals were the most influencing fraction. • Dehydrogenase activity was the most affected soil parameter. • Zinc was the most toxic metal among studied metals.

  1. Sediment composition influences spatial variation in the abundance of human pathogen indicator bacteria within an estuarine environment.

    Directory of Open Access Journals (Sweden)

    Tracy L Perkins

    Full Text Available Faecal contamination of estuarine and coastal waters can pose a risk to human health, particularly in areas used for shellfish production or recreation. Routine microbiological water quality testing highlights areas of faecal indicator bacteria (FIB contamination within the water column, but fails to consider the abundance of FIB in sediments, which under certain hydrodynamic conditions can become resuspended. Sediments can enhance the survival of FIB in estuarine environments, but the influence of sediment composition on the ecology and abundance of FIB is poorly understood. To determine the relationship between sediment composition (grain size and organic matter and the abundance of pathogen indicator bacteria (PIB, sediments were collected from four transverse transects of the Conwy estuary, UK. The abundance of culturable Escherichia coli, total coliforms, enterococci, Campylobacter, Salmonella and Vibrio spp. in sediments was determined in relation to sediment grain size, organic matter content, salinity, depth and temperature. Sediments that contained higher proportions of silt and/or clay and associated organic matter content showed significant positive correlations with the abundance of PIB. Furthermore, the abundance of each bacterial group was positively correlated with the presence of all other groups enumerated. Campylobacter spp. were not isolated from estuarine sediments. Comparisons of the number of culturable E. coli, total coliforms and Vibrio spp. in sediments and the water column revealed that their abundance was 281, 433 and 58-fold greater in sediments (colony forming units (CFU/100g when compared with the water column (CFU/100ml, respectively. These data provide important insights into sediment compositions that promote the abundance of PIB in estuarine environments, with important implications for the modelling and prediction of public health risk based on sediment resuspension and transport.

  2. Use of Geographical Information Systems to influence the selection of sampling site locations for the evaluation of microbial diversity

    Science.gov (United States)

    Soil microbial population densities can easily reach one billion cells per gram of soil; and soil microbial diversity has been estimated to reach ten thousand individual species per gram of soil. Soil type and underlying soil structure are considered primary determinants of microbial community struc...

  3. The influence of nanoflagellates on the spatial variety of picoplankton and the carbon flow of the microbial food web in the oligotrophic subtropical pelagic continental shelf ecosystem

    Science.gov (United States)

    Chiang, Kuo-Ping; Tsai, An-Yi; Tsai, Pei-Jung; Gong, Gwo-Ching; Huang, Bang-Qin; Tsai, Sheng-Fang

    2014-06-01

    To investigate the mechanism of the spatial dynamics of picoplankton community (bacteria and Synechococcus spp.) and to estimate the carbon flux of the microbial food web in the oligotrophic Taiwan Warm Current Water of the subtropical marine pelagic ecosystem, we conducted size-fractionation experiments during five cruises by the R/V Ocean Research II during the summers of 2010 and 2011 in the southern East China Sea. We carried out culture experiments using surface water, which according to a temperature-salinity (T-S) diagram, is characterized as oligotrophic Taiwan Current Warm Water. We found a negative correlation between bacteria growth rate and temperature, and another negative correlation between nitrate and temperature indicating that the active growth of heterotrophic bacteria might be induced by nutrients lifted from a deep layer by cold upwelling water. This finding suggests that the area we studied was a bottom-up control pelagic ecosystem. Upwelling brings nutrient-rich water to the euphotic zone and promotes bacterial growth, resulting in increased picoplankton biomass, which increases the consumption rate of nanoflagellates. The net growth rate (growth rate-grazing rate) becomes negative when the densities of bacteria and Synechococcus spp. are lower than the threshold values. The interaction between growth and grazing will limit the abundance of bacteria (105-106 cells ml-1) and Synechococcus spp. (104-105 cells ml-1) within a narrow range. Meanwhile, 61% of bacteria production and 54% of Synechococcus spp. production are transported to a higher trophic level (nanoflagellate), though the cascade effect might cause an underestimation of both percentages of transported carbon. Based on the successive size-fractionation experiments, we estimated that the predation values were underestimated and that the diet of nanoflagellates is composed of 64% bacteria and 36% Synechococcus spp.

  4. Influence of liming substances and temperature on microbial activity and leaching of soil organic matter in coniferous forest ecosystems

    International Nuclear Information System (INIS)

    Liming has been proposed as a means to counteract the anthropogenic acidification of forest soils in Sweden. The increased pH caused by liming may affect the production and leaching of dissolved organic matter (DOM) from the mor humus layer. The aim of this thesis was to assess changes in leaching of dissolved organic carbon (DOC) and nitrogen (DON) and microbial activity in relation to liming. Leaching experiments were carried out in the laboratory with incubated field-limed soils and by monitoring of dissolved components in lysimeter water collected in a field liming experiment in southern Sweden from 1992-1997. Liming increased the leaching of DOC and DON from the mor humus layer but in the B horizon there were indications of different adsorption properties of DON compared to DOC, which affected the leaching of DOC and DON from the B horizon. DOC leaching was mainly regulated by temperature in mor humus from a site in southern Sweden, while pH had a greater effect in mor humus from a site in northern Sweden. This may have been due to relatively higher bacterial growth in the limed mor humus from southern Sweden. The experiments indicated that bacteria had a decisive role in the microbial production of DOM and bacterial activity was stimulated more by the increase in pH than by the change in the chemical composition of DOM after liming. Field data indicated that increasedCO2 respiration in the limed treatment decreased carbon storage in the mor humus layer. There may have been an increase in carbon and nitrogen storage in the B horizon due to an increased adsorption caused by the higher leaching of DOM from the mor humus layer. The changes in storage could not be confirmed statistically, but there was a significant decline in the C/N ratio in the mor humus layer in the limed treatment. The adsorption patterns of DOC and DON indicated in the field were confirmed in a laboratory experiment

  5. Biotic interactions and sunlight affect persistence of fecal indicator bacteria and microbial source tracking genetic markers in the Upper Mississippi River

    Science.gov (United States)

    Sanitary quality of recreational waters is assessed by enumerating fecal indicator bacteria (FIB) (Escherichia coli and enterococci); organisms present in the gastrointestinal tract of humans and many other animals, hence providing no information about the pollution source. Micro...

  6. Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model

    Institute of Scientific and Technical Information of China (English)

    Fangyue LI; Joachim BEHRENDT; Knut WICHMANN; Ralf OTTERPOHL

    2009-01-01

    In this study, a mathematical model was established to predict the formation of the soluble microbial product (SMP) in a submerged membrane bioreaetor. The developed model was calibrated under the reference condition. Simulation results were in good agreement with the measured results under the reference condition. The calibrated model was then used in the scenario studies to evaluate the effect of three chosen operating parameters: hydraulic retention time (HRT),dissolved oxygen concentration, and sludge retention time (SRT). Simulation results revealed that the SMP dominated the soluble organic substances in the supernatant. The scenario studies also revealed that the HRT can be decreased to 1 h without deteriorating the effluent quality; dissolved oxygen concentration in the reactor can be kept at 2-3 mg/L to maintain the effluent quality, reduce the content of SMP, and minimize operating costs; the optimal SRT can be controlled to 10-15 d to achieve complete nitrification process, less membrane fouling potential, and acceptable organic removal efficiency.

  7. Bacteria and the Aging and Longevity of Caenorhabditis elegans

    OpenAIRE

    Kim, Dennis H.

    2013-01-01

    The molecular genetic analysis of longevity of Caenorhabditis elegans has yielded fundamental insights into evolutionarily conserved pathways and processes governing the physiology of aging. Recent studies suggest that interactions between C. elegans and its microbial environment may influence the aging and longevity of this simple host organism. Experimental evidence supports a role for bacteria in affecting longevity through distinct mechanisms—as a nutrient source, as a potential pathogen ...

  8. Influence of triclosan and triclocarban antimicrobial agents on the microbial activity in three physicochemically differing soils of south Australia

    Directory of Open Access Journals (Sweden)

    Abid Ali, Muhammad Arshad, Zahir A. Zahir

    2011-11-01

    Full Text Available Antimicrobial agents are being used in numerous consumer and health care products on account of which their annual global consumption has reached in millions of kilograms. They are flushed down the drain and become the part of wastewater and sewage sludge and end up in the ultimate sink of agricultural soils. Once they are in the soil, they may disturb the soil’s ecology as a result of which microbial activity useful for soil fertility and biodegradation of xenobiotics may severely be impacted. The present study was designed to assess the influence of two antimicrobial agents triclosan (TCS and triclocarban (TCC, commonly used in consumer and health care products, on the microbial activity in the three agricultural soils from South Australia having different characteristics. The study was laid out following the two factors factorial design by applying 14C-glucose at 5 µg g-1 with either TCS at 0, 30, 90 and 270 µg g-1 or TCC at 0, 50, 150 and 450 µg g-1 in three agricultural soils, Freeling (Typic Rhodoxeralf–sodic, Booleroo (Typic Rhodoxeralf and Avon (Calcixerralic Xerochrepts. The 14CO2, which was released as a result of microbial respiration, was trapped in 3 mL 1M NaOH and was quantified on Wallac WinSpectral α/β 1414 Liquid Scintillation Counter. The results revealed a significant difference in amounts of 14C-glucose mineralized in the three soils. A significant concentration dependant suppressive effect of TCS on the biomineralization of 14C-glucose appeared in all the tested soils as opposed to TCC where no such concentration dependent effect could be recorded. The reduction in 14C-glucose biomineralization in the Freeling, Booleroo and Avon soils was recorded up to 53.6, 38.5 and 37.4 % by TCS at 270 µg g-1 and 13.0, 5.8 and 1.6 % by TCC at 450 µg g-1 respectively. However, a significant negative correlation of CEC and pH was recorded with TCS and TCC effects. These results may imply that presence of such antimicrobial agents

  9. Influence of binder type and process parameters on the compression properties and microbial survival in diclofenac tablet formulations

    Directory of Open Access Journals (Sweden)

    John Oluwasogo Ayorinde

    2011-12-01

    Full Text Available The influence of binder type and process parameters on the compression properties and microbial survival in diclofenac tablet formulations were studied using a novel gum from Albizia zygia. Tablets were produced from diclofenac formulations containing corn starch, lactose and dicalcium phosphate. Formulations were analyzed using the Heckel and Kawakita plots. Determination of microbial viability in the formulations was done on the compressed tablets of both contaminated and uncontaminated tablets prepared from formulations. Direct compression imparted a higher plasticity on the materials than the wet granulation method. Tablets produced by wet granulation presented with a higher crushing strength than those produced by the direct compression method. Significantly higher microbial survival (pA influência do tipo de ligante e os parâmetros do processo de propriedades de compressão e sobrevivência microbiana em comprimidos de diclofenaco foram estudados utilizando uma nova goma de Albizia zygia. Os comprimidos foram produzidos a partir de formulações de diclofenaco contendo amido de milho, lactose e fosfato bicálcico. As formulações foram analisadas usando os gráficos de Heckel e Kawakita. A determinação da viabilidade microbiana nas formulações foi feita nos comprimidos contaminados e não contaminados preparados a partir de formulações. A compressão direta confere maior plasticidade dos materiais do que o método de granulação úmida. Comprimidos produzidos por granulação úmida apresentaram maior força de esmagamento do que aqueles produzidos pelo método de compressão direta. Observou-se sobrevivência significativamente maior (p<0,05 em formulações preparadas por compressão direta. A sobrevivência percentual dos esporos de Bacillus subtilis diminuiu com o aumento da concentração do agregante. O estudo mostrou que a goma de Albizia é capaz de conferir maior plasticidade aos materiais e apresentou maior redução da

  10. Microbial decomposition of dead grassland roots and its influence on the carbon cycle under changing precipitation patterns

    Science.gov (United States)

    Becerra, C.; Schimel, J.

    2013-12-01

    Soil is the largest reservoir of organic carbon in terrestrial ecosystems and as such, represents a potential sink for carbon dioxide.The decomposition products of dead roots buried in the soil is a contributor to soil organic carbon. However, changing precipitation patterns may affect its fate by influencing the microbial community responsible for decomposing dead roots. To assess the impact of changing precipitation patterns, we constructed microcosms with grassland soil collected from the UCSB Sedgwick Reserve, an active and long-term research site, and dead roots from greenhouse-grown grass, Bromus diandrus. Microcosms were wetted continuously, every seven days, or every twenty days. Sets of microcosms were periodically deconstructed to assess the soil versus the roots-associated microbial community and its function. Differences in respiration rates of microcosms continuously wetted or wetted every 7 days versus microcosms wetted every 20 days existed for the first 70 days. After which, no differences in respiration rates were seen with microcosms containing roots and the no roots control. Relatedly, after a 70% roots mass loss by day 50, there was no difference in the respiration rate of microcosms containing roots and the no roots control. More than half of the roots mass loss had occurred by 30 days. By the end of the incubation period, the roots mass loss in continuously wet and 7-day wetted microcosms were over 80% compared to 67% for the microcosms wetted every 20 days. Microbial biomass in the soil were constant over time and showed no difference in treatment except with the no roots control during the first half of the incubation period. Hydrolytic enzyme activities (β-1,4-glucosidase; α-1,4-glucosidase; β-1,4-xylosidase; β-1,4-cellobiosidase) on the roots versus the soil attached to the roots were over an order greater and decreased faster with the exception of N-acetyl-glucosaminidase and acid phosphatase. Oxidative enzyme activities (phenol

  11. Influence of Carbon and Microbial Community Priming on the Attenuation of Uranium in a Contaminated Floodplain Aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Mouser, Paula J.; N' Guessan, A. Lucie; Qafoku, Nikolla; Sinha, M.; Williams, K. H.; Dangelmayr, M.; Resch, Charles T.; Peacock, Aaron D.; Wang, Zheming; Figueroa, Linda A.; Long, P. E.

    2015-07-01

    The capacity for subsurface sediments to sequester metal contaminants, such as uranium (U), and retain them after bioremediation efforts are completed is critical to site stewardship. Sediments enriched in natural organic matter are capable of sequestering significant quantities of U, but may also serve as sources to the aquifer, contributing to plume persistence. Two types of sediments were compared to better understand the mechanisms contributing to the sequestration and release of U in the presence of organic matter. Artificially bioreduced sediments were retrieved from a field experimental plot previously stimulated with acetate while naturally bioreduced sediments were collected from a location enriched in organic matter but never subject to acetate amendment. Batch incubations demonstrated that the artificially bioreduced sediments were primed to rapidly remove uranium from the groundwater whereas naturally bioreduced sediments initially released a sizeable portion of sediment U before U(VI)-removal commenced. Column experiments confirmed that U release persisted for 65 pore volumes in naturally bioreduced sediments, demonstrating the sink-source behavior of this sediment. Acetate addition to artificially bioreduced sediments shifted the microbial community from one dominated by sulfate-reducing bacteria within Desulfobacteraceae to the iron-reducing family Geobacteraceae and Firmicutes during U(VI) reduction. In contrast, initial Geobacteraceae communities innaturally reduced sediments were replaced by clone sequences with similarity to opportunistic Pseudomonas spp. during U release, while U(VI) removal occurred concurrent with enrichment of Firmicutes. These investigations stress the importance of characterizing zones with heterogeneous carbon pools at U contaminated sites prior to the determination of a remedial strategy.

  12. Environmental and microbial factors influencing methane and nitrous oxide fluxes in Mediterranean cork oak woodlands: trees make a difference.

    Science.gov (United States)

    Shvaleva, Alla; Siljanen, Henri M P; Correia, Alexandra; Costa E Silva, Filipe; Lamprecht, Richard E; Lobo-do-Vale, Raquel; Bicho, Catarina; Fangueiro, David; Anderson, Margaret; Pereira, João S; Chaves, Maria M; Cruz, Cristina; Martikainen, Pertti J

    2015-01-01

    Cork oak woodlands (montado) are agroforestry systems distributed all over the Mediterranean basin with a very important social, economic and ecological value. A generalized cork oak decline has been occurring in the last decades jeopardizing its future sustainability. It is unknown how loss of tree cover affects microbial processes that are consuming greenhouse gases in the montado ecosystem. The study was conducted under two different conditions in the natural understory of a cork oak woodland in center Portugal: under tree canopy (UC) and open areas without trees (OA). Fluxes of methane and nitrous oxide were measured with a static chamber technique. In order to quantify methanotrophs and bacteria capable of nitrous oxide consumption, we used quantitative real-time PCR targeting the pmoA and nosZ genes encoding the subunit of particulate methane mono-oxygenase and catalytic subunit of the nitrous oxide reductase, respectively. A significant seasonal effect was found on CH4 and N2O fluxes and pmoA and nosZ gene abundance. Tree cover had no effect on methane fluxes; conversely, whereas the UC plots were net emitters of nitrous oxide, the loss of tree cover resulted in a shift in the emission pattern such that the OA plots were a net sink for nitrous oxide. In a seasonal time scale, the UC had higher gene abundance of Type I methanotrophs. Methane flux correlated negatively with abundance of Type I methanotrophs in the UC plots. Nitrous oxide flux correlated negatively with nosZ gene abundance at the OA plots in contrast to that at the UC plots. In the UC soil, soil organic matter had a positive effect on soil extracellular enzyme activities, which correlated positively with the N2O flux. Our results demonstrated that tree cover affects soil properties, key enzyme activities and abundance of microorganisms and, consequently net CH4 and N2O exchange.

  13. Environmental and microbial factors influencing methane and nitrous oxide fluxes in Mediterranean cork oak woodlands: trees make a difference

    Directory of Open Access Journals (Sweden)

    Alla eShvaleva

    2015-10-01

    Full Text Available Cork oak woodlands (montado are agroforestry systems distributed all over the Mediterranean basin with a very important social, economic and ecological value. A generalized cork oak decline has been occurring in the last decades jeopardizing its future sustainability. It is unknown how loss of tree cover affects microbial processes that are consuming greenhouse gas fluxes in the montado ecosystem. The study was conducted under two different conditions in the natural understory of a cork oak woodland in center Portugal: under tree canopy (UC and open areas without trees (OA. Fluxes of methane and nitrous oxide were measured with a static chamber technique. In order to quantify methanotrophs and bacteria capable of nitrous oxide consumption, we used quantitative real-time PCR targeting the pmoA and nosZ gene encoding the subunit of particulate methane mono-oxygenase and catalytic subunit of the nitrous oxide reductase, respectively. A significant seasonal effect was found on CH4 and N2O fluxes and pmoA and nosZ gene abundance. Tree cover had no effect on methane fluxes; conversely, whereas the UC plots were net emitters of nitrous oxide, the loss of tree cover resulted in a shift in the emission pattern such that the OA plots were a net sink for nitrous oxide. In a seasonal time scale, the UC had higher gene abundance of Type I methanotrophs. Methane flux correlated negatively with abundance of Type I methanotrophs in the UC plots. Nitrous oxide flux correlated negatively with nosZ gene abundance at the OA plots in contrast to that at the UC plots. In the UC soil, SOM had a positive effect on soil extracellular enzyme activities (EEA, which correlated positively with the N2O flux. Our results demonstrated that tree cover affects soil properties, key enzyme activities and abundance of microorganisms and, consequently net CH4 and N2O exchange.

  14. Bacteria in crude oil survived autoclaving and stimulated differentially by exogenous bacteria.

    Science.gov (United States)

    Gong, Xiao-Cui; Liu, Ze-Shen; Guo, Peng; Chi, Chang-Qiao; Chen, Jian; Wang, Xing-Biao; Tang, Yue-Qin; Wu, Xiao-Lei; Liu, Chun-Zhong

    2012-01-01

    Autoclaving of crude oil is often used to evaluate the hydrocarbon-degrading abilities of bacteria. This may be potentially useful for bioaugmentation and microbial enhanced oil recovery (MEOR). However, it is not entirely clear if "endogenous" bacteria (e.g., spores) in/on crude oil survive the autoclaving process, or influence subsequent evaluation of the hydrocarbon-degradation abilities of the "exogenous" bacterial strains. To test this, we inoculated autoclaved crude oil medium with six exogenous bacterial strains (three Dietzia strains, two Acinetobacter strains, and one Pseudomonas strain). The survival of the spore-forming Bacillus and Paenibacillus and the non-spore-forming mesophilic Pseudomonas, Dietzia, Alcaligenes, and Microbacterium was detected using a 16S rRNA gene clone library and terminal restriction fragment length polymorphism (T-RFLP) analysis. However, neither bacteria nor bacterial activity was detected in three controls consisting of non-inoculated autoclaved crude oil medium. These results suggest that detection of endogenous bacteria was stimulated by the six inoculated strains. In addition, inoculation with Acinetobacter spp. stimulated detection of Bacillus, while inoculation with Dietzia spp. and Pseudomonas sp. stimulated the detection of more Pseudomonas. In contrast, similar exogenous bacteria stimulated similar endogenous bacteria at the genus level. Based on these results, special emphasis should be applied to evaluate the influence of bacteria capable of surviving autoclaving on the hydrocarbon-degrading abilities of exogenous bacteria, in particular, with regard to bioaugmentation and MEOR. Bioaugmentation and MEOR technologies could then be developed to more accurately direct the growth of specific endogenous bacteria that may then improve the efficiency of treatment or recovery of crude oil. PMID:23028421

  15. Bacteria in crude oil survived autoclaving and stimulated differentially by exogenous bacteria.

    Directory of Open Access Journals (Sweden)

    Xiao-Cui Gong

    Full Text Available Autoclaving of crude oil is often used to evaluate the hydrocarbon-degrading abilities of bacteria. This may be potentially useful for bioaugmentation and microbial enhanced oil recovery (MEOR. However, it is not entirely clear if "endogenous" bacteria (e.g., spores in/on crude oil survive the autoclaving process, or influence subsequent evaluation of the hydrocarbon-degradation abilities of the "exogenous" bacterial strains. To test this, we inoculated autoclaved crude oil medium with six exogenous bacterial strains (three Dietzia strains, two Acinetobacter strains, and one Pseudomonas strain. The survival of the spore-forming Bacillus and Paenibacillus and the non-spore-forming mesophilic Pseudomonas, Dietzia, Alcaligenes, and Microbacterium was detected using a 16S rRNA gene clone library and terminal restriction fragment length polymorphism (T-RFLP analysis. However, neither bacteria nor bacterial activity was detected in three controls consisting of non-inoculated autoclaved crude oil medium. These results suggest that detection of endogenous bacteria was stimulated by the six inoculated strains. In addition, inoculation with Acinetobacter spp. stimulated detection of Bacillus, while inoculation with Dietzia spp. and Pseudomonas sp. stimulated the detection of more Pseudomonas. In contrast, similar exogenous bacteria stimulated similar endogenous bacteria at the genus level. Based on these results, special emphasis should be applied to evaluate the influence of bacteria capable of surviving autoclaving on the hydrocarbon-degrading abilities of exogenous bacteria, in particular, with regard to bioaugmentation and MEOR. Bioaugmentation and MEOR technologies could then be developed to more accurately direct the growth of specific endogenous bacteria that may then improve the efficiency of treatment or recovery of crude oil.

  16. Adsorption, Persistence and Degradation of Pesticides in Brazilian Soils. Influence of Organic Matter and Microbial Activity

    International Nuclear Information System (INIS)

    Influence of repeated applications of parathion on a humic gley soil was studied. Results showed an increased rate of formation of 14CO2 indicating a more rapid breakdown of parathion after one, five and eleven months storage. The enhanced degradation was shown to occur as a function of the period of incubation, independent of the parathion treatments

  17. Traces of microbial activity in the deep sediment of the Dead Sea: How is life influencing the sedimentary record of this hypersaline lake ?

    Science.gov (United States)

    Thomas, Camille; Ebert, Yael; Kiro, Yael; Stein, Mordechai; Ariztegui, Daniel

    2016-04-01

    As part of the ICDP-sponsored Dead Sea Deep Drilling Project (DSDDP), a multi-disciplinary study has been carried out to understand the influence that microbial communities can have on the Dead Sea sedimentary record. Organic matter (lipids) and DNA extraction have been performed along the main core retrieved from the center of the modern Dead Sea. They revealed different associations of microbial communities, influenced by changing climatic and limnological regimes during sedimentation. Moreover, imaging and chemical characterization of authigenic iron-sulfur minerals have revealed the unexpected presence of an active sulfur cycle in the sediment. In particular, their morphology and Fe/S ratios are coherent with incomplete sulfate reduction, limited by sulfur reduction, and often resulting in the preservation of greigite. In glacial period intervals, pyritization may be complete, indicating full sulfate reduction probably allowed by significant accumulation of organic matter in the alternating aragonite and detritus (aad) facies. The DSDDP core provides a unique opportunity to investigate deep diagenetic processes and to assess the role of microbial activity in the Dead Sea hypersaline sediment. Our study shows that this microbial activity influences the carbon and sulfur phases, as well as magnetic fractions, potentially affecting proxies used for paleoenvironmental and paleoclimatic reconstructions.

  18. Social environment has a primary influence on the microbial and odor profiles of a chemically signaling songbird

    Directory of Open Access Journals (Sweden)

    Danielle June Whittaker

    2016-08-01

    Full Text Available Chemical signaling is an underappreciated means of communication among birds, as may be the potential contributions of symbiotic microbes to animal chemical communication in general. The dark-eyed junco (Junco hyemalis produces and detects volatile compounds that may be important in reproductive behavior. These compounds are found in preen oil secreted by the uropygial gland, and this gland supports diverse bacterial communities including genera known to produce some of these volatile compounds. We investigated the relative contributions of shared environments and genetic relatedness in shaping juncos’ symbiotic bacterial communities, and investigated whether these bacterial communities underlie juncos’ chemical signaling behavior. We sampled parents and nestlings at 9 junco nests during one breeding season at Mountain Lake Biological Station in Virginia, USA. From each individual, we collected swabs of the uropygial gland and the cloaca, preen oil, and a small blood sample for paternity testing. We characterized junco bacterial communities through 16S rRNA gene surveys and preen oil volatile compounds via gas chromatography-mass spectrometry. Nest membership and age class had the strongest influence on the structure of bacterial and volatile profiles. We compared father-offspring similarity based on paternity, and nestling similarity in nests containing full siblings and half siblings, and found that relatedness did not noticeably affect bacterial or volatile profiles. While we cannot rule out an influence of genetic relatedness on these profiles, it is clear that shared environments are more influential in shaping bacterial and volatile profiles among juncos.We did not find significant covariation between individual bacterial and volatile profiles. Possible explanations for this result include: 1 bacteria do not underlie volatile production; 2 ample redundancy in volatile production among bacterial types obscures covariation; or 3 the

  19. Microbial studies in the Canadian nuclear fuel waste management program

    International Nuclear Information System (INIS)

    Atomic Energy of Canada Limited (AECL) has developed a concept for permanent geological disposal of nuclear fuel waste in Canada. An accelerated program was initiated in 1991 to address and quantify the potential effects of microbial action on the integrity of the disposal concept's multiple barrier system. This microbial program focuses on answering specific questions in areas such as the survival of bacteria in compacted clay-based buffer materials under relevant radiation and desiccation conditions; mobility of microbes in compacted buffer materials; the potential for microbially-influenced corrosion of containers; microbial gas production in backfill material; introduction of nutrients as a result of vault excavation and operation; the presence and activity of microbes in deep granitic groundwaters; and the effects of biofilms on radionuclide migration in the geosphere. This paper summarizes the current research activities at AECL in these areas. (author)

  20. Triclocarban Influences Antibiotic Resistance and Alters Anaerobic Digester Microbial Community Structure.

    Science.gov (United States)

    Carey, Daniel E; Zitomer, Daniel H; Hristova, Krassimira R; Kappell, Anthony D; McNamara, Patrick J

    2016-01-01

    Triclocarban (TCC) is one of the most abundant organic micropollutants detected in biosolids. Lab-scale anaerobic digesters were amended with TCC at concentrations ranging from the background concentration of seed biosolids (30 mg/kg) to toxic concentrations of 850 mg/kg to determine the effect on methane production, relative abundance of antibiotic resistance genes, and microbial community structure. Additionally, the TCC addition rate was varied to determine the impacts of acclimation time. At environmentally relevant TCC concentrations (max detect = 440 mg/kg), digesters maintained function. Digesters receiving 450 mg/kg of TCC maintained function under gradual TCC addition, but volatile fatty acid concentrations increased, pH decreased, and methane production ceased when immediately fed this concentration. The concentrations of the mexB gene (encoding for a multidrug efflux pump) were higher with all concentrations of TCC compared to a control, but higher TCC concentrations did not correlate with increased mexB abundance. The relative abundance of the gene tet(L) was greater in the digesters that no longer produced methane, and no effect on the relative abundance of the class 1 integron integrase encoding gene (intI1) was observed. Illumina sequencing revealed substantial community shifts in digesters that functionally failed from increased levels of TCC. More subtle, yet significant, community shifts were observed in digesters amended with TCC levels that did not inhibit function. This research demonstrates that TCC can select for a multidrug resistance encoding gene in mixed community anaerobic environments, and this selection occurs at concentrations (30 mg/kg) that can be found in full-scale anaerobic digesters (U.S. median concentration = 22 mg/kg, mean = 39 mg/kg).

  1. The Seasonality of Fecal Coliform Bacteria Pollution and its Influence on Closures of Shellfish Harvesting Areas in Mississippi Sound

    Directory of Open Access Journals (Sweden)

    Paul B. Tchounwou

    2005-08-01

    Full Text Available Runoff from agricultural lands and farm animal feedlots is one of the major sources of fecal coliforms in surface waters, and fecal coliform (FC bacteria concentrations tend to vary with season because of seasonal variations in climatic factors. However, El Niño -Southern Oscillation (ENSO events may affect the extent and patterns of seasonality in FC levels in coastal waters. Water quality monitoring data for shellfish management collected during El Niño (1990, 1992, 1997, and La Niña (1999, 2000 years were analyzed to evaluate the extent to which these events influenced Pearl River stage, and bacterial levels, water temperature, and salinity in the western part of Mississippi Sound. Models to predict FC levels in relation to various environmental factors were also developed. In 1990, 1992 and 1997, FC geometric mean counts peaked in late winter (January/February reaching 120 MPN (February 1990, 165 MPN (January 1992, and 86 MPN (January 1997, and then decreased considerably during spring and summer (1.2 – 19 MPN. Thereafter, FC abundance increased slightly in fall and early winter (1.9 – 24 MPN. Fecal coliform abundance during the 2000 La Niña year was much lower (1.0 – 10.3 MPN than in 1992 (1.2 – 165 MPN, and showed no seasonal pattern from January to August, perhaps due to the relative scarcity of rainfall in 2000. In 1995 (ENSO neutral year, peak geometric mean FC count (46 MPN was lower than during El Niño years and occurred in early spring (March. The seasonal and between year variations in FC levels determined the number of days during which the conditionally approved shellfish growing area was opened for harvesting shellfish. For example, from January to April 1997, the area was not opened for shellfish harvesting, whereas in 2000, the number of days during which the area was opened ranged from 6 - 27 (January to April to 24 - 26 (October to December

  2. The seasonality of fecal coliform bacteria pollution and its influence on closures of shellfish harvesting areas in Mississippi Sound.

    Science.gov (United States)

    Chigbu, Paulinus; Gordon, Scott; Tchounwou, Paul B

    2005-08-01

    Runoff from agricultural lands and farm animal feedlots is one of the major sources of fecal coliforms in surface waters, and fecal coliform (FC) bacteria concentrations tend to vary with season because of seasonal variations in climatic factors. However, El Niño--Southern Oscillation (ENSO) events may affect the extent and patterns of seasonality in FC levels in coastal waters. Water quality monitoring data for shellfish management collected during El Niño (1990, 1992, 1997), and La Niña (1999, 2000) years were analyzed to evaluate the extent to which these events influenced Pearl River stage, and bacterial levels, water temperature, and salinity in the western part of Mississippi Sound. Models to predict FC levels in relation to various environmental factors were also developed. In 1990, 1992 and 1997, FC geometric mean counts peaked in late winter (January/February) reaching 120 MPN (February 1990), 165 MPN (January 1992), and 86 MPN (January 1997), and then decreased considerably during spring and summer (1.2 - 19 MPN). Thereafter, FC abundance increased slightly in fall and early winter (1.9 - 24 MPN). Fecal coliform abundance during the 2000 La Niña year was much lower (1.0 -10.3 MPN) than in 1992 (1.2 - 165 MPN), and showed no seasonal pattern from January to August, perhaps due to the relative scarcity of rainfall in 2000. In 1995 (ENSO neutral year), peak geometric mean FC count (46 MPN) was lower than during El Niño years and occurred in early spring (March). The seasonal and between year variations in FC levels determined the number of days during which the conditionally approved shellfish growing area was opened for harvesting shellfish. For example, from January to April 1997, the area was not opened for shellfish harvesting, whereas in 2000, the number of days during which the area was opened ranged from 6 - 27 (January to April) to 24 - 26 (October to December). ENSO events thus influenced the extent and timing of the peak levels of fecal

  3. Influence of sub-lethal stresses on the survival of lactic acid bacteria after spray-drying in orange juice.

    Science.gov (United States)

    Barbosa, J; Borges, S; Teixeira, P

    2015-12-01

    The demand for new functional non-dairy based products makes the production of a probiotic orange juice powder an encouraging challenge. However, during drying process and storage, loss of viability of the dried probiotic cultures can occur, since the cells are exposed to various stresses. The influence of sub-lethal conditions of temperature, acidic pH and hydrogen peroxide on the viability of Pediococcus acidilactici HA-6111-2 and Lactobacillus plantarum 299v during spray drying in orange juice and subsequent storage under different conditions was investigated. At the end of storage, the survival of both microorganisms through simulated gastro-intestinal tract (GIT) conditions was also determined. The viability of cells previously exposed to each stress was not affected by the drying process. However, during 180 days of storage at room temperature, unlike P. acidilactici HA-6111-2, survival of L. plantarum 299v was enhanced by prior exposure to sub-lethal conditions. Previous exposure to sub-lethal stresses of each microorganism did not improve their viability after passage through simulated GIT. Nevertheless, as cellular inactivation during 180 days of storage was low, both microorganisms were present in numbers of ca. 10(7) cfu/mL at the end of GIT. This is an indication that both bacteria are good candidates for use in the development of an orange juice powder with functional characteristics.

  4. Fermentation of Lactic Acid Bacteria in Silage and Influence Factors%青贮乳酸菌的发酵及影响发酵的因素

    Institute of Scientific and Technical Information of China (English)

    赵彩艳; 尤跃钧

    2011-01-01

    The key of improving feed quality is the fermentation conditions of lactic acid bacteria which were created. In this paper, Fermentation mechanism of lactic acid bacteria in silage making processe and influence factors on the fermentation were laborated. The purpose was to provide reference on high quality silage making.%提高青贮饲料质量的关键是创造乳酸发酵的条件。文章对乳酸菌在青贮饲料制作过程中的发酵机制及其影响乳酸菌发酵的因素进行了阐述。

  5. Influence of natural substrates and co-occurring marine bacteria on the production of secondary metabolites by Photobacterium halotolerans

    DEFF Research Database (Denmark)

    Månsson, Maria; Giobergia, Sonia; Møller, Kirsten A.;

    Genome sequences reveal that our current standard laboratory conditions only support a fraction of the potential secondary metabolism in bacteria. Thus, we must rethink cultivation, detection, and isolation strategies for bacterial secondary metabolites in order to explore the huge, so far unchar...... uncharacterized chemical potential of these organisms. We are currently investigating the use of natural substrates and co-cultures with commensal bacteria to elicit or alter production of antibacterial compounds in marine bacteria....

  6. Potential effects of bacteria on radionuclide transport from a Swedish high level nuclear waste repository

    International Nuclear Information System (INIS)

    Microorganisms can influence radionuclide migration if their concentration are high in comparison with other organic particles. Data on the numbers of microorganisms in undisturbed ground-water have been collected. The average number of cells in the samples from 17 levels in 5 boreholes was 3.0 x 105 cells ml-1. A biofilm experiment indicated an active microbial rock surface population. Radiographic uptake experiments suggest inactive bulk water populations. The bulk water microbial cells in deep ground water might then be inactive cells detached from active biofilms. Enrichment cultures for anaerobic bacteria demonstrated the presence of anaerobic bacteria capable of growth on C-1 compounds with hydrogen and carbon dioxide, presumably methanogenic bacteria. Further, growth in enrichment cultures with sulphate as electron-acceptor and lactate as carbon source proved dissimilatory sulphate reducing bacteria to be present. (author)

  7. The soil microbial community composition and soil microbial carbon uptake are more affected by soil type than by different vegetation types (C3 and C4 plants) and seasonal changes

    Science.gov (United States)

    Griselle Mellado Vazquez, Perla; Lange, Markus; Gleixner, Gerd

    2016-04-01

    This study investigates the influence of different vegetation types (C3 and C4 plants), soil type and seasonal changes on the soil microbial biomass, soil microbial community composition and soil microbial carbon (C) uptake. We collected soil samples in winter (non-growing season) and summer (growing season) in 2012 from an experimental site cropping C3 and C4 plants for 6 years on two different soil types (sandy and clayey). The amount of phospholipid fatty acids (PLFAs) and their compound-specific δ13C values were used to determined microbial biomass and the flow of C from plants to soil microorganisms, respectively. Higher microbial biomass was found in the growing season. The microbial community composition was mainly explained by soil type. Higher amounts of SOC were driving the predominance of G+ bacteria, actinobacteria and cyclic G- bacteria in sandy soils, whereas root biomass was significantly related to the increased proportions of G- bacteria in clayey soils. Plant-derived C in G- bacteria increased significantly in clayey soils in the growing season. This increase was positively and significantly driven by root biomass. Moreover, changes in plant-derived C among microbial groups pointed to specific capabilities of different microbial groups to decompose distinct sources of C. We concluded that soil texture and favorable growth conditions driven by rhizosphere interactions are the most important factors controlling the soil microbial community. Our results demonstrate that a change of C3 plants vs. C4 plants has only a minor effect on the soil microbial community. Thus, such experiments are well suited to investigate soil organic matter dynamics as they allow to trace the C flow from plants into the soil microbial community without changing the community abundance and composition.

  8. Rumen bacteria

    International Nuclear Information System (INIS)

    The rumen is the most extensively studied gut community and is characterized by its high population density, wide diversity and complexity of interactions. This complex, mixed microbial culture is comprised of prokaryote organisms including methane-producing archaebacteria, eukaryote organisms, such as ciliate and flagellate protozoa, anaerobic phycomycete fungi and bacteriophage. Bacteria are predominant (up to 1011 viable cells per g comprising 200 species) but a variety of ciliate protozoa occur widely (104-106/g distributed over 25 genera). The anaerobic fungi are also widely distributed (zoospore population densities of 102-104/g distributed over 5 genera). The occurrence of bacteriophage is well documented (107-109 particles/g). This section focuses primarily on the widely used methods for the cultivation and the enumeration of rumen microbes, especially bacteria, which grow under anaerobic conditions. Methods that can be used to measure hydrolytic enzymes (cellulases, xylanases, amylases and proteinases) are also described, along with cell harvesting and fractionation procedures. Brief reference is also made to fungi and protozoa, but detailed explanations for culturing and enumerating these microbes is presented in Chapters 2.4 and 2.5

  9. Bovine Host Genetic Variation Influences Rumen Microbial Methane Production with Best Selection Criterion for Low Methane Emitting and Efficiently Feed Converting Hosts Based on Metagenomic Gene Abundance.

    Directory of Open Access Journals (Sweden)

    Rainer Roehe

    2016-02-01

    Full Text Available Methane produced by methanogenic archaea in ruminants contributes significantly to anthropogenic greenhouse gas emissions. The host genetic link controlling microbial methane production is unknown and appropriate genetic selection strategies are not developed. We used sire progeny group differences to estimate the host genetic influence on rumen microbial methane production in a factorial experiment consisting of crossbred breed types and diets. Rumen metagenomic profiling was undertaken to investigate links between microbial genes and methane emissions or feed conversion efficiency. Sire progeny groups differed significantly in their methane emissions measured in respiration chambers. Ranking of the sire progeny groups based on methane emissions or relative archaeal abundance was consistent overall and within diet, suggesting that archaeal abundance in ruminal digesta is under host genetic control and can be used to genetically select animals without measuring methane directly. In the metagenomic analysis of rumen contents, we identified 3970 microbial genes of which 20 and 49 genes were significantly associated with methane emissions and feed conversion efficiency respectively. These explained 81% and 86% of the respective variation and were clustered in distinct functional gene networks. Methanogenesis genes (e.g. mcrA and fmdB were associated with methane emissions, whilst host-microbiome cross talk genes (e.g. TSTA3 and FucI were associated with feed conversion efficiency. These results strengthen the idea that the host animal controls its own microbiota to a significant extent and open up the implementation of effective breeding strategies using rumen microbial gene abundance as a predictor for difficult-to-measure traits on a large number of hosts. Generally, the results provide a proof of principle to use the relative abundance of microbial genes in the gastrointestinal tract of different species to predict their influence on traits e

  10. Bovine Host Genetic Variation Influences Rumen Microbial Methane Production with Best Selection Criterion for Low Methane Emitting and Efficiently Feed Converting Hosts Based on Metagenomic Gene Abundance.

    Science.gov (United States)

    Roehe, Rainer; Dewhurst, Richard J; Duthie, Carol-Anne; Rooke, John A; McKain, Nest; Ross, Dave W; Hyslop, Jimmy J; Waterhouse, Anthony; Freeman, Tom C; Watson, Mick; Wallace, R John

    2016-02-01

    Methane produced by methanogenic archaea in ruminants contributes significantly to anthropogenic greenhouse gas emissions. The host genetic link controlling microbial methane production is unknown and appropriate genetic selection strategies are not developed. We used sire progeny group differences to estimate the host genetic influence on rumen microbial methane production in a factorial experiment consisting of crossbred breed types and diets. Rumen metagenomic profiling was undertaken to investigate links between microbial genes and methane emissions or feed conversion efficiency. Sire progeny groups differed significantly in their methane emissions measured in respiration chambers. Ranking of the sire progeny groups based on methane emissions or relative archaeal abundance was consistent overall and within diet, suggesting that archaeal abundance in ruminal digesta is under host genetic control and can be used to genetically select animals without measuring methane directly. In the metagenomic analysis of rumen contents, we identified 3970 microbial genes of which 20 and 49 genes were significantly associated with methane emissions and feed conversion efficiency respectively. These explained 81% and 86% of the respective variation and were clustered in distinct functional gene networks. Methanogenesis genes (e.g. mcrA and fmdB) were associated with methane emissions, whilst host-microbiome cross talk genes (e.g. TSTA3 and FucI) were associated with feed conversion efficiency. These results strengthen the idea that the host animal controls its own microbiota to a significant extent and open up the implementation of effective breeding strategies using rumen microbial gene abundance as a predictor for difficult-to-measure traits on a large number of hosts. Generally, the results provide a proof of principle to use the relative abundance of microbial genes in the gastrointestinal tract of different species to predict their influence on traits e.g. human metabolism

  11. [Influence of different slope position and profile in Disporopsis pernyi forest land on soil microbial biomass and enzyme activity in southwest Karst mountain of China ].

    Science.gov (United States)

    Qin, Hua-Jun; He, Bing-Hui; Zhao, Xuan-chi; Li, Yuan; Mao, Wen-tao; Zeng, Qing-ping

    2014-09-01

    Soil microbial biomass and enzyme activity are important parameters to evaluate the quality of the soil environment. The goal of this study was to determine the influence of different slope position and section in Disporopsis pernyi forest land on the soil microbial biomass and enzyme activity in southwest Karst Mountain. In this study, we chose the Dip forest land at Yunfo village Chengdong town Liangping country Chongqing Province as the study object, to analyze the influence of three different slope positions [Up Slope(US), Middle Slope(MS), Below Slope(BS)] and two different sections-upper layer(0-15 cm) and bottom layer(15-30 cm) on the soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), microbial carbon entropy (qMBC), microbial nitrogen entropy (qMBN) , catalase(CAT), alkaline phosphatase (ALK), urease(URE), and invertase(INV). The results showed that the same trend (BS > MS > US) was found for SMBC, SMBN, qMBC, qMBN, CAT and INV of upper soil layer, while a different trend (BS > US > MS) was observed for ALK. In addition, another trend (MS > US > BS) was observed for URE. The same trend (BS > MS >US) was observed for SMBN, qMBN, CAT, ALK, URE and INV in bottom layer, but a different trend (MS > BS > US) was observed for SMBC and qMBC. The SMBC, SMBN, CAT, ALK, URE and INV manifested as upper > bottom with reduction of the section, while qMBC and qMBN showed the opposite trend. Correlation analysis indicated that there were significant (P enzyme activity and moisture. According to the two equations of regression analysis, SMBC tended to increase with the increasing CAT and ALK, while decreased with the increasing pH. Then SMBN tended to increase with the increasing URE and INV. PMID:25518682

  12. The influence of microbial mats on the formation of sand volcanoes and mounds in the Red Sea coastal plain, south Jeddah, Saudi Arabia

    Science.gov (United States)

    Taj, Rushdi J.; Aref, Mahmoud A. M.; Schreiber, B. Charlotte

    2014-08-01

    Extensive areas covered by microbial mats have been found in the upper intertidal flats and supratidal pools in the Red Sea coastal plain of south Jeddah, Saudi Arabia. Numerous microbially controlled sediment-surface morphologies are evident, such as flat cohesive mats that commonly pass into mats with wrinkles, reticulates, and tufts, together with erosion pockets and mat chips. These microbial mats form cohesive surface layers that lead to biostabilization of the sediment surface. Fluidization of the underlying sediments is due to tidal influences and pressurized gas escape from decay and photosynthesis of microbial mats and causes deformation and rupture of the cohesive surface mat layer via vertical and sub-vertical pipes. Extrusion of fluidized sediments and water through these pipes leads to redeposition of sediment grains above the surface mat layer to form sand volcanoes and mounds. Most of the sand volcanoes present in the intertidal flats and supratidal pools show a symmetrical morphology, whereas in tidal channels asymmetrical forms are more common. Extrusion of underlying sediments through several adjacent vents leads to coalescence of sand volcanoes to form sand mounds. In this study sand volcanoes are also compared with other cone-like features from the Red Sea, such as gas domes and crab mounds. This comparison should help in differentiating similar cone-like features associated with microbial mats in the rock record.

  13. An approach towards assessing the effects of microbially-influenced corrosion in nuclear waste systems

    Energy Technology Data Exchange (ETDEWEB)

    Pritchard, A.M. [Corrosion and Fouling Consultancy, 33 Laburnum Road, Oxford OX2 9EL (United Kingdom)

    2003-07-01

    Microorganisms are inevitably present in nuclear waste systems. There are no models to predict their influence on corrosion rates, since the mechanisms are poorly understood. A database of MIC corrosion rates is being assembled to allow some prediction of such rates, and thus the associated risk, for defined situations. No long-term predictions are possible, since such data are lacking, and most published short-term data lack important detail. However, both qualitative and quantitative data indicate conditions that are often associated with MIC, and which should therefore be avoided by design, operation and management of waste repositories. (author)

  14. Influence of lactic acid bacteria on redox status and on proteolytic activity of buckwheat (Fagopyrum esculentum Moench) sourdoughs.

    Science.gov (United States)

    Capuani, Alessandro; Behr, Jürgen; Vogel, Rudi F

    2013-07-15

    Redox potential and proteolysis determine protein networks in doughs and thus dough rheology as well as the structure of baked goods. Namely, gluten-free bakery products needs structural improvements but little is known about these parameters in gluten free dough systems. In this work the influence of lactic acid bacteria (LAB) on redox status and proteolysis of buckwheat sourdoughs was investigated. An increase of free thiol groups was detected as redox potential was decreasing during fermentation. Thiol content at 8 h was higher in doughs fermented with strains with high reductive activity, such as Weissella (W.) cibaria in comparison to Pediococcus (P.) pentosaceus, which exhibited a lower reducing activity. At 24 h each fermentation showed a similar content of free thiol groups. Endogenous buckwheat proteases were characterized using various protease inhibitors in buckwheat doughs. Until pH3.1 a proteolysis increase was monitored in doughs. Employed LAB didn't show any detectable extracellular proteolytic activity. Flour proteases are thus responsible for protein breakdown, and this was demonstrated comparing free amino nitrogen (FAN) values and protein electrophoretic patterns of sourdough fermentations with chemical acidified (CA) doughs. FAN content at 24 h using P. pentosaceus, proteolytic comparative strain of Enterococcus faecalis, W. cibaria, mixed culture (containing P. pentosaceus and W. cibaria), CA and CA doughs containing glutathione (GSH) reached 45.9±1.3, 42.4±1.3, 40±1, 31±2, 29±2 and 17.8±3.9 mmol kg(-1) flour, respectively. Proteolysis was mainly influenced by pH and incubation time. The addition of GSH showed a decrease of proteolysis and of free amino acids. CA doughs showed a higher total free amino acids content than sourdough fermented with LAB indicating their metabolization. Fermentations with high FAN values exhibited lower band intensity (analyzed under reducing condition) in electrophoretic patterns. These results show that

  15. Influence of lactic acid bacteria on redox status and on proteolytic activity of buckwheat (Fagopyrum esculentum Moench) sourdoughs.

    Science.gov (United States)

    Capuani, Alessandro; Behr, Jürgen; Vogel, Rudi F

    2013-07-15

    Redox potential and proteolysis determine protein networks in doughs and thus dough rheology as well as the structure of baked goods. Namely, gluten-free bakery products needs structural improvements but little is known about these parameters in gluten free dough systems. In this work the influence of lactic acid bacteria (LAB) on redox status and proteolysis of buckwheat sourdoughs was investigated. An increase of free thiol groups was detected as redox potential was decreasing during fermentation. Thiol content at 8 h was higher in doughs fermented with strains with high reductive activity, such as Weissella (W.) cibaria in comparison to Pediococcus (P.) pentosaceus, which exhibited a lower reducing activity. At 24 h each fermentation showed a similar content of free thiol groups. Endogenous buckwheat proteases were characterized using various protease inhibitors in buckwheat doughs. Until pH3.1 a proteolysis increase was monitored in doughs. Employed LAB didn't show any detectable extracellular proteolytic activity. Flour proteases are thus responsible for protein breakdown, and this was demonstrated comparing free amino nitrogen (FAN) values and protein electrophoretic patterns of sourdough fermentations with chemical acidified (CA) doughs. FAN content at 24 h using P. pentosaceus, proteolytic comparative strain of Enterococcus faecalis, W. cibaria, mixed culture (containing P. pentosaceus and W. cibaria), CA and CA doughs containing glutathione (GSH) reached 45.9±1.3, 42.4±1.3, 40±1, 31±2, 29±2 and 17.8±3.9 mmol kg(-1) flour, respectively. Proteolysis was mainly influenced by pH and incubation time. The addition of GSH showed a decrease of proteolysis and of free amino acids. CA doughs showed a higher total free amino acids content than sourdough fermented with LAB indicating their metabolization. Fermentations with high FAN values exhibited lower band intensity (analyzed under reducing condition) in electrophoretic patterns. These results show that

  16. Responses of Pinus halepensis growth, soil microbial catabolic functions and phosphate-solubilizing bacteria after rock phosphate amendment and ectomycorrhizal inoculation

    OpenAIRE

    Ouahmane, L.; Revel, J.C.; Hafidi, M; Thioulouse, J.; Prin, Y.; Galiana, A; Dreyfus, Bernard; Duponnois, Robin

    2009-01-01

    We examined the effects of an ectomycorrhizal (EM) fungus, Pisolithus sp., on of the growth of Pinus halepensis (Allepo pine) seedlings, soil microbial functions and rock phosphate solubilization in a un-disinfected soil amended or not with a Moroccan rock phosphate. Allepo pine seedlings were inoculated with an EM fungus (Pisolithus sp. strain PH4) isolated from a P. halepensis plantation and selected for its high ability to mobilize P from an inorganic form of phosphate. After 4 month's cul...

  17. From Mantle to Microbe to Mollusc: How Animal-Microbial Symbioses Influence Carbon and Sulfur Cycling in Hydrothermal Vent Flows.

    Science.gov (United States)

    Girguis, P. R.; Beinart, R.

    2014-12-01

    Symbioses between animals and chemoautotrophic bacteria dominate many hydrothermal vents. In these associations, symbiotic bacteria harness energy and "fix" carbon from the oxidation of reduced chemicals such as sulfide, methane, and hydrogen that are found in venting fluids. At vents along the Eastern Lau Spreading Center (ELSC) in the South Pacific, snails and mussels with chemoautotrophic symbionts have been shown to harness energy via the oxidation of sulfide. However, partially oxidized sulfur species such as thiosulfate and polysulfides have also been detected in abundance in their habitats. No studies to date have established whether thiosulfate or other partially oxidized sulfur compounds are used by these symbiotic associations, nor have studies constrained the potential role that symbioses might play in sulfur biogeochemical cycles at diffuse vent flows. To address these questions, we used high-pressure, flow through incubations to study three symbiotic molluscs from the ELSC - the snails Alviniconcha and Ifremeria nautilei and the mussel Bathymodiolus brevior - at conditions mimicking those in situ. Via the use of isotopically labeled inorganic carbon, shipboard mass spectrometry and voltammetric microelectrodes, we quantified the production and consumption of different sulfur compounds by each of these symbioses. We established that the uptake and oxidation of either sulfide or thiosulfate could -to varying degrees- support carbon fixation in all three species. Notably, we also observed that some symbioses excreted thiosulfate and polysulfides under sulfidic conditions, suggesting that these symbioses are a source of partially oxidized sulfur species in the environment. We further observed spatial disparity in the carbon fixation rates among the individuals in our incubations that have implications for the variability of productivity in situ.Collectively, these data reveal that thiosulfate can support net autotrophy, and may be an ecologically important

  18. Isolation and screening of lactic acid bacteria and preparation of microbial ecological agents%乳酸菌的分离筛选及其微生态制剂的制备

    Institute of Scientific and Technical Information of China (English)

    刘变芳; 雒丹; 石磊

    2011-01-01

    该研究用市售酸奶中分离纯化到的乳酸菌株和实验室保藏的多种乳酸菌株作为材料,研究不同乳酸菌对大肠杆菌、沙门氏菌、志贺氏菌、金黄色葡萄球菌4种致病菌株的抑菌作用.采用双层平板法从出发菌株中选育到对致病菌株有明显抑制功能的乳酸菌,并将抗菌性能良好的乳酸菌株进行优化组合.组合菌剂转接到脱脂乳中,静置培养48h后,采用真空冷冻干燥技术制备乳酸菌微生态制剂.试验结果表明,从原始菌株中选育到11株对4种致病菌有较强抑制功能的乳酸菌株;优化组合乳酸菌在MRS培养液中,静置培养17h活菌数达到最大值;冷冻干燥过程采用2%麦芽糖作为保护剂,微生态制剂中乳酸菌活菌数为3.36× 105cfu/g,存活率达到68.6%.%Antibacterial effect of lactic acid bacteria purified from yogurt and preserved in our laboratory on pathogenic strains of Higellae pathogenic, Staphylococcus aureus, Salmonella, and Escherichia coli were studied. Double-plate method was adopted to select lactic acid bacteria that had a significant inhibition function on pathogenic strains, and lactic acid bacteria strains with good anti-bacterial performances was combined and optimized. Combined strains were inoculated with skim milk to produce microbial ecological agents of lactic acid bacteria by vacuum freeze-drying after 48h static culture. The experimental results shown that among the original lactic acid bacteria strains, eleven strains had significant inhibition effect on the four pathogenic strains, and the number of optimized combination reach its peak after 17h static culture in MRS medium. When using 2% of maltose as protective agent, the number of survival bacteria was 3.36x105cfu/g, the survival rate of lactic acid bacteria in microbial ecological agents after vacuum freeze-drying could reach 68.6%.

  19. Evaluating the influence of process parameters on soluble microbial products formation using response surface methodology coupled with grey relational analysis.

    Science.gov (United States)

    Xu, Juan; Sheng, Guo-Ping; Luo, Hong-Wei; Fang, Fang; Li, Wen-Wei; Zeng, Raymond J; Tong, Zhong-Hua; Yu, Han-Qing

    2011-01-01

    Soluble microbial products (SMPs) present a major part of residual chemical oxygen demand (COD) in the effluents from biological wastewater treatment systems, and the SMP formation is greatly influenced by a variety of process parameters. In this study, response surface methodology (RSM) coupled with grey relational analysis (GRA) method was used to evaluate the effects of substrate concentration, temperature, NH(4)(+)-N concentration and aeration rate on the SMP production in batch activated sludge reactors. Carbohydrates were found to be the major component of SMP, and the influential priorities of these factors were: temperature>substrate concentration > aeration rate > NH(4)(+)-N concentration. On the basis of the RSM results, the interactive effects of these factors on the SMP formation were evaluated, and the optimal operating conditions for a minimum SMP production in such a batch activated sludge system also were identified. These results provide useful information about how to control the SMP formation of activated sludge and ensure the bioreactor high-quality effluent. PMID:20832838

  20. The microbial food web in the Doñana marshland: Influence of trophic state and hydrology

    Science.gov (United States)

    Àvila, Núria; López-Flores, Rocío; Quintana, Xavier D.; Serrano, Laura

    2016-10-01

    We investigated the composition of the microbial food web in the marshland of Doñana National Park (SW Spain). We analysed factors affecting the predominance of autotrophic (A) or heterotrophic (H) microorganisms in a set of 16 marshland water bodies that differ in their hydrological pattern. Autotrophic organisms were predominant in the Doñana marshland, with autotrophs between 0.3 and 25.3 times higher than heterotrophs in biomass. The variance partitioning analysis using the log A:H biomass ratio (A/H) as a response variable revealed that water body spatial position accounted for the largest portion of total variance (16% of unique effects), followed by environmental variables (13%), with a shared variation of 24%. Zooplankton biomass had no significant influence on A/H ratio. The two first axes of RDA analysis were related to soluble reactive phosphate (SRP) and dissolved inorganic nitrogen (DIN) concentrations respectively. Cyanobacteria were predominant in waters with high SRP, while other organisms were distributed in relation to DIN by their size, with small organisms predominating with low DIN and large ones with high DIN. Spatial effects reflect the importance of location with respect to the water source in this marshland, where flooding areas are very much dominated by autotrophs, while confined areas, which are a long way from nutrient sources, have a more balanced abundance of autotrophs and heterotrophs.

  1. How do changes in dissolved oxygen concentration influence microbially-controlled phosphorus cycling in stream biofilms?

    Science.gov (United States)

    Saia, S. M.; Locke, N. A.; Regan, J. M.; Carrick, H. J.; Buda, A. R.; Walter, M. T.

    2014-12-01

    Advances in molecular microbiology techniques (e.g. epi-fluorescent microscopy and PCR) are making it easier to study the influence of specific microorganisms on nutrient transport. Polyphosphate accumulating organisms (PAOs) are commonly used in wastewater treatment plants to remove excess phosphorus (P) from effluent water. PAOs have also been identified in natural settings but their ecological function is not well known. In this study, we tested the hypothesis that PAOs in natural environments would release and accumulate P during anaerobic and aerobic conditions, respectively. We placed stream biofilms in sealed, covered tubs and subjected them to alternating air (aerobic conditions) and N2 gas (anaerobic condition) bubbling for 12 hours each. Four treatments investigated the influence of changing dissolved oxygen on micribially-controlled P cycling: (1) biofilms bubbled continuously with air, (2) biofilms bubbled alternatively with air and N2, (3) biocide treated biofilms bubbled continuously with air, and (4) biocide treated biofilms bubbled alternatively with air and N2. Treatments 3 and 4 serve as abiotic controls to treatments 1 and 2. We analyzed samples every 12 hours for soluble reactive P (SRP), temperature, dissolved oxygen, and pH. We also used fluorescent microscopy (i.e. DAPI staining) and PCR to verify the presence of PAOs in the stream biofilms. SRP results over the course of the experiment support our hypothesis that anaerobic and aerobic stream conditions may impact PAO mediated P release and uptake, respectively in natural environments. The results of these experiments draw attention to the importance of microbiological controls on P mobility in freshwater ecosystems.

  2. The microbial ecology of wine grape berries.

    Science.gov (United States)

    Barata, A; Malfeito-Ferreira, M; Loureiro, V

    2012-02-15

    Grapes have a complex microbial ecology including filamentous fungi, yeasts and bacteria with different physiological characteristics and effects upon wine production. Some species are only found in grapes, such as parasitic fungi and environmental bacteria, while others have the ability to survive and grow in wines, constituting the wine microbial consortium. This consortium covers yeast species, lactic acid bacteria and acetic acid bacteria. The proportion of these microorganisms depends on the grape ripening stage and on the availability of nutrients. Grape berries are susceptible to fungal parasites until véraison after which the microbiota of truly intact berries is similar to that of plant leaves, which is dominated by basidiomycetous yeasts (e.g. Cryptococcus spp., Rhodotorula spp. Sporobolomyces spp.) and the yeast-like fungus Aureobasidium pullulans. The cuticle of visually intact berries may bear microfissures and softens with ripening, increasing nutrient availability and explaining the possible dominance by the oxidative or weakly fermentative ascomycetous populations (e.g. Candida spp., Hanseniaspora spp., Metschnikowia spp., Pichia spp.) approaching harvest time. When grape skin is clearly damaged, the availability of high sugar concentrations on the berry surface favours the increase of ascomycetes with higher fermentative activity like Pichia spp. and Zygoascus hellenicus, including dangerous wine spoilage yeasts (e.g. Zygosaccharomyces spp., Torulaspora spp.), and of acetic acid bacteria (e.g. Gluconobacter spp., Acetobacter spp.). The sugar fermenting species Saccharomyces cerevisiae is rarely found on unblemished berries, being favoured by grape damage. Lactic acid bacteria are minor partners of grape microbiota and while being the typical agent of malolactic fermentation, Oenococcus oeni has been seldom isolated from grapes in the vineyard. Environmental ubiquitous bacteria of the genus Enterobacter spp., Enterococcus spp., Bacillus spp

  3. Activity and Composition of Ammonia-Oxidizing Bacteria in an Aquic Brown Soil as Influenced by Land Use and Fertilization

    Institute of Scientific and Technical Information of China (English)

    YU Wan-Tai; XU Yong-Gang; BI Ming-Li; MA Qiang; ZHOU Hua

    2010-01-01

    The effects of long-term(19 years)different land use and fertilization on activity and composition of ammonia-oxidizing bacteria(AOB)in an aquic brown soil were investigated in a field experiment in Liaoning Province,China.The 19-year experiment conducted from 1990 to 2008 involved seven treatments designed: cropping rotation of soybean-corn-corn with no fertilizer(control,CK),recycled manure(RM),fertilizer nitrogen(N),phosphorous(P)and potassium(K)(NPK),NPK+RM,and no-crop bare land,mowed fallow,and non-mowed fallow.The results showed that the potential nitrification rates of the RM,NPK+RM,mowed fallow,and non-mowed fallow treatments were significantly higher(P < 0.05)than those of the CK and NPK treatments,indicating that the long-term applications of recycled manure and return of plant residues both significantly increased the activity of AOB.Although the application of NPK did not enhance soil potential nitrification because of decreased pH,available K had an important effect on potential nitrification.Denaturing gradient gel electrophoresis(DGGE)fingerprint profiles showed that no-crop treatments had an increase in the diversity of the AOB community compared to the CK,RM,and NPK treatments,implying that agricultural practices,especially tillage,had an adverse effect on the soil AOB community.The NPK+RM treatment had the most diverse DGGE patterns possibly because of the increased available P in this treatment.A phylogenetic analysis showed that most of the DGGE bands derived belonged to Nitrosoxpira cluster 3,not Nitrosospira cluster 2.These demonstrated that different land use and fertilization significantly influenced the activity and composition of the AOB community by altering the soil properties,mainly including pH,total C,available K,and available P.

  4. Microbial biofilm growth on irradiated, spent nuclear fuel cladding

    International Nuclear Information System (INIS)

    A fundamental criticism regarding the potential for microbial influenced corrosion in spent nuclear fuel cladding or storage containers concerns whether the required microorganisms can, in fact, survive radiation fields inherent in these materials. This study was performed to unequivocally answer this critique by addressing the potential for biofilm formation, the precursor to microbial-influenced corrosion, in radiation fields representative of spent nuclear fuel storage environments. This study involved the formation of a microbial biofilm on irradiated spent nuclear fuel cladding within a hot cell environment. This was accomplished by introducing 22 species of bacteria, in nutrient-rich media, to test vessels containing irradiated cladding sections and that was then surrounded by radioactive source material. The overall dose rate exceeded 2 Gy/h gamma/beta radiation with the total dose received by some of the bacteria reaching 5 x 103 Gy. This study provides evidence for the formation of biofilms on spent-fuel materials, and the implication of microbial influenced corrosion in the storage and permanent deposition of spent nuclear fuel in repository environments

  5. Stronger influence of litter quality on decomposition rates than microbial home field advantage in novel subtropical dry forests

    Science.gov (United States)

    Marin-Spiotta, E.; Atkinson, E. E.

    2015-12-01

    Litter decomposition is one of the most studied ecosystem processes, given its role in carbon cycling and nutrient availability, yet our knowledge of how decomposition is influenced by novel species assemblages in tropical forests emerging on post-agricultural landscapes is limited. This is especially true in tropical dry forests, which are some of the most fragmented forests worldwide due to human pressures and sensitive to changes in rainfall and fire regimes. Here we tested for the effects of litter quality, site conditions, and microbial "home-field advantage" on decomposition rates in subtropical dry forests in St. Croix, U.S. Virgin Islands. We conducted a 22-month in situ and reciprocal transplant field decomposition experiment of aboveground litter and fine roots in 10-year old sites dominated by an early successional N-fixing tree and 40-year old mixed-species secondary forests. Total annual litterfall mass did not differ between the two forest types, but monthly amounts did, with more litter accumulating in the 40-year old secondary forests during the dry season and in the 10-year old secondary forests during the wet season. Litter chemistry differed between the two forest types and showed divergent patterns over the two-year field incubation. To test for the effects of litter quality on decomposition rates, we compared mass loss rates for aboveground and root litter from each forest decomposed in situ and transplanted to the other forest type. Litter in the 10-year old forests decomposed faster in situ (k= 1.07 ± 0.04) than when it was transplanted (k=0.86 ± 0.04). Litter from the 40-year old forests showed the opposite pattern. In situ root decomposition in both forests occurred at the same rate compared to roots that were transplanted there from the other forest type, suggesting that site conditions were equally important as litter quality. Our results were not consistent with a microbial home-field advantage for litter and root decomposition, that