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Sample records for bacteria influence microbial

  1. 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...

  2. 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...... feed level (H0, H2, H4 and H6). Fibre digestibility was not significantly affected by tallow addition. Increasing tallow level in the diet decreased the total VFA concentration, the ratio of acetic acid to propionic acid and the ammonia concentration in the rumen. Crude fat and fatty acid content...... in bacterial and protozoal dry matter increased with increased tallow level, especially due to an increase in fatty acids originating from the feeds. Microbial synthesis in the rumen and flow of amino acids to the duodenum was highest for medium fat intake at the high feed level....

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. Counting viruses and bacteria in photosynthetic microbial mats.

    Science.gov (United States)

    Carreira, Cátia; Staal, Marc; Middelboe, Mathias; Brussaard, Corina P D

    2015-03-01

    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 typically used in benthic viral ecology were applied to the complex matrix of microbial mats but were found to inefficiently extract viruses. Here, we present a method for extraction and quantification of viruses from photosynthetic microbial mats using epifluorescence microscopy (EFM) and flow cytometry (FCM). A combination of EDTA addition, probe sonication, and enzyme treatment applied to a glutaraldehyde-fixed sample resulted in a substantially higher viral (5- to 33-fold) extraction efficiency and reduced background noise compared to previously published methods. Using this method, it was found that in general, intertidal photosynthetic microbial mats harbor very high viral abundances (2.8 × 10(10) ± 0.3 × 10(10) g(-1)) compared with benthic habitats (10(7) to 10(9) g(-1)). This procedure also showed 4.5- and 4-fold-increased efficacies of extraction of viruses and bacteria, respectively, from intertidal sediments, allowing a single method to be used for the microbial mat and underlying sediment.

  8. 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.

  9. 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.

  10. 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 carbon steel must be monitored on-line in order to provide an efficient protection and control the corrosion. A number of monitoring techniques is industrially used today, and the applicability and reliability of these for monitoring MIC is evaluated. Coupons and ER are recommended as necessary basic...... techniques even though localised corrosion rate cannot be measured. FSM measures general corrosion and detects localised corrosion, but the sensitivity is not high enough for monitoring initiation of pitting and small attacks. Electrochemical techniques as LPR and EIS give distorted data and unreliable...

  11. Counting viruses and bacteria in photosynthetic microbial mats

    NARCIS (Netherlands)

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

    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

  12. Comparative Assessment of Mediterranean Gorgonian-Associated Microbial Communities Reveals Conserved Core and Locally Variant Bacteria

    KAUST Repository

    van de Water, Jeroen A J M

    2016-10-10

    Gorgonians are key habitat-forming species of Mediterranean benthic communities, but their populations have suffered from mass mortality events linked to high summer seawater temperatures and microbial disease. However, our knowledge on the diversity, dynamics and function of gorgonian-associated microbial communities is limited. Here, we analysed the spatial variability of the microbiomes of five sympatric gorgonian species (Eunicella singularis, Eunicella cavolini, Eunicella verrucosa, Leptogorgia sarmentosa and Paramuricea clavata), collected from the Mediterranean Sea over a scale of ∼1100 km, using next-generation amplicon sequencing of the 16S rRNA gene. The microbiomes of all gorgonian species were generally dominated by members of the genus Endozoicomonas, which were at very low abundance in the surrounding seawater. Although the composition of the core microbiome (operational taxonomic units consistently present in a species) was found to be unique for each host species, significant overlap was observed. These spatially consistent associations between gorgonians and their core bacteria suggest intricate symbiotic relationships and regulation of the microbiome composition by the host. At the same time, local variations in microbiome composition were observed. Functional predictive profiling indicated that these differences could be attributed to seawater pollution. Taken together, our data indicate that gorgonian-associated microbiomes are composed of spatially conserved bacteria (core microbiome members) and locally variant members, and that local pollution may influence these local associations, potentially impacting gorgonian health.

  13. Counting Viruses and Bacteria in Photosynthetic Microbial Mats

    OpenAIRE

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

    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 typically used in benthic viral ecology were applied to the complex matrix of microbial mats but were found to inefficiently extract viruses. Here, we present a method for extraction and quantifica...

  14. Diversity and distribution in hypersaline microbial mats of bacteria related to Chloroflexus spp

    DEFF Research Database (Denmark)

    Nübel, Ulrich; Bateson, Mary M.; Madigan, Michael T.;

    2001-01-01

    primers for the specific amplification of 16S rRNA genes from filamentous phototrophic bacteria within the kingdom of "green nonsulfur bacteria." PCR products recovered from microbial mats in a saltern in Guerrero Negro, Mexico, were subjected to cloning or denaturing gradient gel electrophoresis...

  15. 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

  16. Monitoring Techniques for Microbially Influenced Corrosion of Carbon Steel

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    2000-01-01

    and control the corrosion. A number of monitoring techniques is industrially used today, and the applicability and reliability of these for monitoring MIC is evaluated. Coupons and ER are recommended as necessary basic techniques even though localised corrosion rate cannot be measured. FSM measures general......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...... corrosion and detects localised corrosion, but the sensitivity is not high enough for monitoring initiation of pitting and small attacks. Electrochemical techniques as LPR and EIS give distorted data and unreliable corrosion rates, when biofilm and corrosion products cover the steel surface. However, EIS...

  17. 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.

  18. Endospores of thermophilic bacteria as tracers of microbial dispersal by ocean currents.

    Science.gov (United States)

    Müller, Albert Leopold; de Rezende, Júlia Rosa; Hubert, Casey R J; Kjeldsen, Kasper Urup; Lagkouvardos, Ilias; Berry, David; Jørgensen, Bo Barker; Loy, Alexander

    2014-06-01

    Microbial biogeography is influenced by the combined effects of passive dispersal and environmental selection, but the contribution of either factor can be difficult to discern. As thermophilic bacteria cannot grow in the cold seabed, their inactive spores are not subject to environmental selection. We therefore conducted a global experimental survey using thermophilic endospores that are passively deposited by sedimentation to the cold seafloor as tracers to study the effect of dispersal by ocean currents on the biogeography of marine microorganisms. Our analysis of 81 different marine sediments from around the world identified 146 species-level 16S rRNA phylotypes of endospore-forming, thermophilic Firmicutes. Phylotypes showed various patterns of spatial distribution in the world oceans and were dispersal-limited to different degrees. Co-occurrence of several phylotypes in locations separated by great distances (west of Svalbard, the Baltic Sea and the Gulf of California) demonstrated a widespread but not ubiquitous distribution. In contrast, Arctic regions with water masses that are relatively isolated from global ocean circulation (Baffin Bay and east of Svalbard) were characterized by low phylotype richness and different compositions of phylotypes. The observed distribution pattern of thermophilic endospores in marine sediments suggests that the impact of passive dispersal on marine microbial biogeography is controlled by the connectivity of local water masses to ocean circulation.

  19. 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

    as 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...... 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...... phytoplankton and the ambient microbial community...

  20. 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

  1. [Characteristics of microbial community structure during isolation of electrical active bacteria].

    Science.gov (United States)

    Wang, Min; Zhao, Yang- Guo; Lu, Shan-Shan

    2014-10-01

    To investigate the effect of selective culturing on microorganisms and functional role of electrical active bacteria in biofilm, some exoelectrogens were isolated from microbial fuel cell (MFC) anodic biofilm using Hungate roll-tube technique with iron oxide as indicator. At the same time, the dynamics of the microbial community structure was monitored during the pure culture isolation. The results show that maximum voltages of MFCs feeding with lactic acid, acetic acid and steroid wastewater are 0.57, 0.60 and 0.40 V respectively. The dominant bacteria isolated from seed sludge and anodic films feeding with acetate and lactate belong to phylum Proteobacteria; while steroid wastewater contains relative high diversity of bacteria, i. e. Proteobacteria, Firmicutes and Bacteroidetes. After enriching and culturing, two bacteria were consequently obtained, which shared the highest similarity with Enterobacter ludwigii and Citrobacter freundii respectively. When inoculated in MFC with lactic acid as the substrate, they produced maximum voltage of 0.10 and 0.17 V individually. This study shows that electrical active bacteria can be isolated from the MFC anodic biofilm using anaerobic gradient dilution culture techniques with iron oxide as indicator. Microbial community structure presents markedly shifting during the bacteria isolation owing to its selectivity.

  2. 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...

  3. 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.

  4. Influence of microbially enriched vermicompost on yield, microbial dynamics and soil nutrients

    Directory of Open Access Journals (Sweden)

    Neeldurai Tensingh Baliah

    2016-12-01

    Full Text Available The present study has been conducted to explore the microbial enrichment of vermicompost with microbial inoculants such as Azospirillum brasilense, Bacillus megaterium and Pseudomonas fluorescens. The enrichment had a positive effect on the crop response, soil biological activity and soil nutrient status. The results indicated that the enriched vermicompost significantly increased crop response of Okra with reference to yield attributes. Further, the microbial enriched vermicompost significantly improved the soil microbial dynamics such as bacteria and fungi and nutrient status such as total N and available P in the amended soil. The enrichment with agronomically important microbes such as nitrogen fixer, phosphate solubilizer and plant growth promoting rhizobacteria had positive response but the response varied among the beneficial microorganisms.

  5. 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.

  6. 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; Sawant, S.S.

    carried out with natural marine biofilms from a tropical monsoon-influenced environment to evaluate the interactions between bacteria and diatoms through application of antibiotics (streptomycin and chloramphenicol). Overall, chloramphenicol inhibited...

  7. 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...

  8. 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.

  9. Influence of xenobiotic contaminants on landfill soil microbial activity and diversity.

    Science.gov (United States)

    Pérez-Leblic, M I; Turmero, A; Hernández, M; Hernández, A J; Pastor, J; Ball, A S; Rodríguez, J; Arias, M E

    2012-03-01

    Landfills are often the final recipient of a range of environmentally important contaminants such as hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). In this study the influence of these contaminants on microbial activity and diversity was assessed in a municipal solid waste (MSW) landfill placed in Torrejón de Ardoz (Madrid, Spain). Soil samples were collected from four selected areas (T2, T2B, T8 and T9) in which the amount of total hydrocarbons, PAHs and PCBs were measured. Soil biomass, substrate induced respiration (SIR) and physiological profiles of soil samples were also determined and used as indicators of total microbial activity. Highest concentration of total hydrocarbons was detected in T2 and T9 samples, with both PCBs and benzopyrene being detected in T9 sample. Results corresponding to microbial estimation (viable bacteria and fungi, and SIR) and microbiological enzyme activities showed that highest values corresponded to areas with the lowest concentration of hydrocarbons (T2B and T8). It is noticeable that in such areas was detected the lowest concentration of the pollutants PAHs and PCBs. A negative significant correlation between soil hydrocarbons concentration and SIR, total bacteria and fungi counts and most of the enzyme activities determined was established. DGGE analysis was also carried out to determine the microbial communities' structure in the soil samples, establishing different profiles of Bacteria and Archaea communities in each analysed area. Through the statistical analysis a significant negative correlation was only found for Bacteria domain when Shannon index and hydrocarbon concentration were correlated. In addition, a bacterial 16S rRNA gene based clone library was prepared from each soil. From the clones analysed in the samples, the majority corresponded to Proteobacteria, followed by Acidobacteria and Actinobacteria. It is important to remark that the most polluted sample (T9) showed

  10. Quantifying the structure of the mesopelagic microbial loop from observed depth profiles of bacteria and protozoa

    Directory of Open Access Journals (Sweden)

    T. F. Thingstad

    2004-08-01

    Full Text Available t is widely recognized that organic carbon exported to the ocean aphotic layer is significantly consumed by heterotrophic organisms such as bacteria and zooplankton in the mesopelagic layer. However, very little is known for the trophic link between bacteria and zooplankton or the structure of the microbial loop in this layer. In the northwestern Mediterranean, recent studies have shown that viruses, bacteria, heterotrophic nanoflagellates, and ciliates distribute down to 2000 m with group-specific depth-dependent decreases, and that bacterial production decreases with depth down to 1000 m. Here we show that such data can be analyzed using a simple steady-state food chain model to quantify the carbon flow from bacteria to zooplankton over the mesopelagic layer. The model indicates that a similar amount of bacterial production is allocated to viruses and heterotrophic nanoflagellates, and that heterotrophic nanoflagellates are the important remineralizers.

  11. Microbial production of polyhydroxyalkanoates by bacteria isolated from oil wastes.

    Science.gov (United States)

    Wong, A L; Chua, H; Yu, P H

    2000-01-01

    A Gram-positive coccus-shaped bacterium capable of synthesizing higher relative molecular weight (M(r)) poly-hydroxybutyrate (PHB) was isolated from sesame oil and identified as Staphylococcus epidermidis (by Microbial ID, Inc., Newark, NJ). The experiment was conducted by shake flask fermentation culture using media containing fructose. Cell growth up to a dry mass of 2.5 g/L and PHB accumulation up to 15.02% of cell dry wt was observed. Apart from using single carbohydrate as a sole carbon source, various industrial food wastes including sesame oil, ice cream, malt, and soya wastes were investigated as nutrients for S. epidermidis to reduce the cost of the carbon source. As a result, we found that by using malt wastes as nutrient for cell growth, PHB accumulation of S. epidermidis was much better than using other wastes as nutrient source. The final dried cell mass and PHB production using malt wastes were 1.76 g/L and 6.93% polymer/cells (grams/gram), and 3.5 g/L and 3.31% polymer/cells (grams/gram) in shake flask culture and in fermentor culture, respectively. The bacterial polymer was characterized by 1H-nuclear magnetic resonance (NMR), 13C-NMR, Fourier transform infrared, and differential scanning calorimetry. The results show that with different industrial food wastes as carbon and energy sources, the same biopolymer (PHB) was obtained. However, the use of sesame oil as the carbon source resulted in the accumulation of PHB with a higher melting point than that produced from other food wastes as carbon sources by this organism under similar experimental conditions.

  12. Microbial metabolism of loganin by intestinal bacteria and identification of new metabolites in rat.

    Science.gov (United States)

    Li, Xiaona; Huo, Changhong; Wang, Qiao; Zhang, Xiaowei; Sheng, Xiaona; Zhang, Lantong

    2008-04-01

    Loganin is an important constituent of the traditional Chinese medicine Fructus Corni, with several bioactivities. Microbial metabolism of loganin by intestinal bacteria was investigated. Two metabolites (log-1 and log-2) were isolated from anaerobic culture and their structures were identified by means of their ESI-MS, (1)H-NMR, (13)C-NMR and 2D-NMR spectral data. Log-1 was an aglycone of loganin and log-2 was proved to be a new compound. In vivo metabolites of loganin were detected in rat urine, bile and feces after oral administration of loganin and the structures were proved to be identical with that of the microbial metabolites log-1 and log-2 by HPLC-PDA analysis and comparison with the reference standards. Therefore we can prepare metabolites by anaerobic culture with intestinal bacteria.

  13. The influence of six pharmaceuticals on freshwater sediment microbial growth incubated at different temperatures and UV exposures.

    Science.gov (United States)

    Veach, Allison; Bernot, Melody J; Mitchell, James K

    2012-07-01

    Pharmaceutical compounds have been detected in freshwater for several decades. Once they enter the aquatic ecosystem, they may be transformed abiotically (i.e., photolysis) or biotically (i.e., microbial activity). To assess the influence of pharmaceuticals on microbial growth, basal salt media amended with seven pharmaceutical treatments (acetaminophen, caffeine, carbamazepine, cotinine, ibuprofen, sulfamethoxazole, and a no pharmaceutical control) were inoculated with stream sediment. The seven pharmaceutical treatments were then placed in five different culture environments that included both temperature treatments of 4, 25, 37°C and light treatments of continuous UV-A or UV-B exposure. Microbial growth in the basal salt media was quantified as absorbance (OD(550)) at 7, 14, 21, 31, and 48d following inoculation. Microbial growth was significantly influenced by pharmaceutical treatments (P microbial communities post-incubation identified selection of microbial and fungal species with exposure to caffeine, cotinine, and ibuprofen at 37°C; acetaminophen, caffeine, and cotinine at 25°C; and carbamazepine exposed to continuous UV-A. Bacillus and coccus cellular arrangements (1000X magnification) were consistently observed across incubation treatments for each pharmaceutical treatment although carbamazepine and ibuprofen exposures incubated at 25°C also selected spiral-shaped bacteria. These data indicate stream sediment microbial communities are influenced by pharmaceuticals though physiochemical characteristics of the environment may dictate microbial response.

  14. Decoupling of DAMO archaea from DAMO bacteria in a methane-driven microbial fuel cell.

    Science.gov (United States)

    Ding, Jing; Lu, Yong-Ze; Fu, Liang; Ding, Zhao-Wei; Mu, Yang; Cheng, Shuk H; Zeng, Raymond J

    2017-03-01

    Anaerobic oxidation of methane (AOM) contributes significantly to the global methane sink. Previously, studies of anaerobic methanotrophic (ANME) archaea have been limited as they have not been separable from their bacterial partners during the AOM process because of their dependence on the bacteria. A microbial fuel cell (MFC) is a device capable of directly transforming chemical energy to electrical energy via electrochemical reactions involving biochemical pathways. In this study, decoupling of denitrifying anaerobic methane oxidation (DAMO) archaea and DAMO bacteria was investigated in an microbial fuel cell (MFC) using methane as the fuel. The DAMO fuel cell worked successfully but demonstrated weak electrogenic capability with around 25 mV production. After 45 days' enrichment, the sequencing and fluorescence in situ hybridization results showed the DAMO archaea percentage had increased from 26.96% (inoculum) to 65.77% (electrode biofilm), while the DAMO bacteria percentage decreased from 24.39% to 2.07%. Moreover, the amount of ANME-2d had doubled in the electrode biofilm compared with the inoculum. The sequencing results also showed substantial enrichment of the Ignavibacterium and Geobacter genera. The roles of Ignavibacterium and Geobacter in the MFC system need to be further investigated. Nevertheless, these results illustrate that an MFC device may provide a possible approach to separate DAMO archaea from DAMO bacteria.

  15. 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.

  16. Influence of substrate and microbial interaction on efficiency of rumen microbial growth.

    Science.gov (United States)

    Demeyer, D; Van Nevel, C

    1986-01-01

    Microbial N produced in the rumen and flowing to the duodenum (Ni) is related to the total amount of OM fermented or apparently digested in the rumen (OMf). This relationship, best expressed as microbial N yield (gNi/kgOMf), is affected mainly by the physical and chemical properties of feed carbohydrates and the amounts ingested. These factors influence yields at three levels of increasing complexity: Bacterial fermentation within one compartment following the continuous culture model. Fermentation pattern as such does not seem to affect yields. High fermentation rates are associated with lactate production, low methane production and transient polysaccharide synthesis. These effects induce acidification and lower yields, partly compensated by faster growth. Protozoal action, determined by the presence of sequestration spaces provided mainly by roughage diets. The presence of protozoa depresses microbial N yield but allows more complete fibre digestion. Compartmentation and differential passage. With roughage diets, optimal microbial N yield seems to require well developed microbial compartmentation, involving a large proportion of microbes in a large-particle pool with a slow turnover, balanced by a small proportion in liquid, small-particle pools with a fast turnover. Such a situation is associated with long roughage feeding. It is hypothesized that microbial N yields in the rumen may vary between two extremes which are associated with the feeding of long roughage on the one hand or with concentrate (starch) feeding on the other.

  17. 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.

  18. Isolation and genetic identification of PAH degrading bacteria from a microbial consortium.

    Science.gov (United States)

    Molina, M Carmen; González, Natalia; Bautista, L Fernando; Sanz, Raquel; Simarro, Raquel; Sánchez, Irene; Sanz, José L

    2009-11-01

    Polycyclic aromatic hydrocarbons (PAH; naphthalene, anthracene and phenanthrene) degrading microbial consortium C2PL05 was obtained from a sandy soil chronically exposed to petroleum products, collected from a petrochemical complex in Puertollano (Ciudad Real, Spain). The consortium C2PL05 was highly efficient degrading completely naphthalene, phenanthrene and anthracene in around 18 days of cultivation. The toxicity (Microtox method) generated by the PAH and by the intermediate metabolites was reduced to levels close to non-toxic in almost 40 days of cultivation. The identified bacteria from the contaminated soil belonged to gamma-proteobacteria and could be include in Enterobacter and Pseudomonas genus. DGGE analysis revealed uncultured Stenotrophomonas ribotypes as a possible PAH degrader in the microbial consortium. The present work shows the potential use of these microorganisms and the total consortium for the bioremediation of PAH polluted areas since the biodegradation of these chemicals takes place along with a significant decrease in toxicity.

  19. STUDIES ON MICROBIAL DIVERSITY OF POLYGALACTURONASE PRODUCING BACTERIA FROM THE SOIL OF VEGETABLES MARKET OF PATAN

    Directory of Open Access Journals (Sweden)

    SANJAY PATEL , DIPIKA PANDYA AND S.A. BHATT

    2014-12-01

    Full Text Available ABSTRACT: Present work is carried out to check the study microbial diversity of polygalacturonase producing bacteria from the soil of fruits and vegetables market. Soil which is continuously dumped with waste of fruits and vegetables are rich sources of biopolymer viz, pectin, cellulose and hemicellulose. Presence of such biopolymer selectively promotes the growth of microorganisms which have potential to degrade pectin. In this study more than one hundred and twenty bacterial species are isolated from the soil on the basis of their cell and colony morphology. From these isolates, forty five bacterial species found to produce polygalacturonase enzyme and same have check for capability to produce protease and amylase enzyme. This study provides useful information of the microbial diversity of the soil of fruits and vegetable market. Further it is helpful to study the metabolism of microorganisms to degrade diverse biopolymer.

  20. 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

    Microbial enhanced oil recovery (MEOR) utilizes microbes for enhancing the recovery by several mechanisms, among which the most studied are the following: (1) reduction of oil-water interfacial tension (IFT) by the produced biosurfactant and (2) selective plugging by microbes and metabolic products...... is modification of the relative permeabilities by decreasing the interfacial tension. Attachment of bacteria reduces the pore space available for flow, i.e., the effective porosity and permeability. Clogging of specific areas may occur. An extensive study of the MEOR on the basis of the developed model has...

  1. 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

  2. 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)

  3. 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.

  4. 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.

  5. Microbial and chemical composition of liquid-associated bacteria in goats' rumen and fermenters.

    Science.gov (United States)

    Abecia, L; Soto, E C; Ramos-Morales, E; Molina-Alcaide, E

    2014-10-01

    This study was undertaken to investigate the relationship between chemical composition and microbial profile of rumen liquid-associated bacteria (LAB) in vivo (Murciano-Granadina goats) and in a rumen simulation system (single-flow continuous-culture fermenters). To achieve this aim, analyses of purine bases along with some molecular techniques (quantitative PCR to assess abundance and DGGE to identify biodiversity and bacterial profile) were carried out. A control diet (AHC) based on alfalfa hay (AH) and concentrate (C) in a 1:1 ratio and two experimental diets (AHCBI and AHCBII), in which concentrate was partially replaced with multinutrient blocks, were used. Diets AHCBI and AHCBII included multinutrient blocks differing in the relative amount of two-stage olive cake and the source of protein (sunflower meal vs. fava beans). We aimed to investigate the effect of these blocks on rumen microbiota to evaluate their potential as safe substitutes of cereal-based concentrates. Similar patterns of response to diet were found for chemical composition, microbial abundances and diversity in LAB isolated from goat's rumen and fermenters. Whereas bacterial density (log10 gene copies/g FM: 11.6 and 9.4 for bacteria and methanogens, respectively, in rumen) and diversity indexes (Shannon index: 3.6) were not affected by diet, DGGE analyses showed that bacterial community profile was affected. The cluster analysis suggested differences in bacterial profile between LAB pellets isolated from the rumen of goat and fermenters. A relationship between chemical composition and bacterial community composition in LAB pellets seems to exist. Changes in the former were reflected in the bacterial community profile. Further research is needed to clarify the relationship between chemical and microbial composition of ruminal bacterial pellets with diets of different quality.

  6. Beyond bacteria: a study of the enteric microbial consortium in extremely low birth weight infants.

    Directory of Open Access Journals (Sweden)

    Mariam Susan LaTuga

    Full Text Available Extremely low birth weight (ELBW infants have high morbidity and mortality, frequently due to invasive infections from bacteria, fungi, and viruses. The microbial communities present in the gastrointestinal tracts of preterm infants may serve as a reservoir for invasive organisms and remain poorly characterized. We used deep pyrosequencing to examine the gut-associated microbiome of 11 ELBW infants in the first postnatal month, with a first time determination of the eukaryote microbiota such as fungi and nematodes, including bacteria and viruses that have not been previously described. Among the fungi observed, Candida sp. and Clavispora sp. dominated the sequences, but a range of environmental molds were also observed. Surprisingly, seventy-one percent of the infant fecal samples tested contained ribosomal sequences corresponding to the parasitic organism Trichinella. Ribosomal DNA sequences for the roundworm symbiont Xenorhabdus accompanied these sequences in the infant with the greatest proportion of Trichinella sequences. When examining ribosomal DNA sequences in aggregate, Enterobacteriales, Pseudomonas, Staphylococcus, and Enterococcus were the most abundant bacterial taxa in a low diversity bacterial community (mean Shannon-Weaver Index of 1.02 ± 0.69, with relatively little change within individual infants through time. To supplement the ribosomal sequence data, shotgun sequencing was performed on DNA from multiple displacement amplification (MDA of total fecal genomic DNA from two infants. In addition to the organisms mentioned previously, the metagenome also revealed sequences for gram positive and gram negative bacteriophages, as well as human adenovirus C. Together, these data reveal surprising eukaryotic and viral microbial diversity in ELBW enteric microbiota dominated bytypes of bacteria known to cause invasive disease in these infants.

  7. Influence of transitional states on the microbial ecology of anaerobic digesters treating solid wastes.

    Science.gov (United States)

    Regueiro, Leticia; Veiga, Patricia; Figueroa, Mónica; Lema, Juan M; Carballa, Marta

    2014-03-01

    A better understanding of the microbial ecology of anaerobic processes during transitional states is important to achieve a long-term efficient reactor operation. Five wastes (pig manure, biodiesel residues, ethanol stillage, molasses residues, and fish canning waste) were treated in five anaerobic reactors under the same operational conditions. The influence of the type of substrate and the effect of modifying feeding composition on the microbial community structure was evaluated. The highest biomethanation efficiency was observed in reactors fed with fish canning waste, which also presented the highest active archaeal population and the most diverse microbial communities. Only two Bacteria populations could be directly related to a particular substrate: Ilyobacter with biodiesel residues and Trichococcus with molasses residues. Results showed that the time to achieve steady-state performance after these transitional states was not dependent on the substrate treated. But reactors needed more time to handle the stress conditions derived from the start-up compared to the adaptation to a new feeding. Cluster analyses showed that the type of substrate had a clear influence on the microbiology of the reactors, and that segregation was related to the reactors performance. Finally, we conclude that the previous inoculum history treating solid waste and higher values of active Archaea population are important factors to face a successful change in substrate not entailing stability failure.

  8. 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.

  9. Influence of bacteria on film formation inhibiting corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Gunasekaran, G.; Chongdar, Shobhana; Gaonkar, S.N.; Kumar, Pradeep

    2004-08-01

    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.

  10. 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

  11. Effects of Exogenous Yeast and Bacteria on the Microbial Population Dynamics and Outcomes of Olive Fermentations.

    Science.gov (United States)

    Zaragoza, Jose; Bendiks, Zachary; Tyler, Charlotte; Kable, Mary E; Williams, Thomas R; Luchkovska, Yelizaveta; Chow, Elaine; Boundy-Mills, Kyria; Marco, Maria L

    2017-01-01

    In this study, we examined Sicilian-style green olive fermentations upon the addition of Saccharomyces cerevisiae UCDFST 09-448 and/or Pichia kudriazevii UCDFST09-427 or the lactic acid bacteria (LAB) Lactobacillus plantarum AJ11R and Leuconostoc pseudomesenteroides BGM3R. Olives containing S. cerevisiae UCDFST 09-448, a strain able to hydrolyze pectin, but not P. kudriazevii UCDFST 09-427, a nonpectinolytic strain, exhibited excessive tissue damage within 4 weeks. DNA sequencing of fungal internal transcribed spacer (ITS) regions and comparisons to a yeast-specific ITS sequence database remarkably showed that neither S. cerevisiae UCDFST 09-448 nor P. kudriazevii UCDFST 09-427 resulted in significant changes to yeast species diversity. Instead, Candida boidinii constituted the majority (>90%) of the total yeast present, independent of whether S. cerevisiae or P. kudriazevii was added. By comparison, Lactobacillus species were enriched in olives inoculated with potential starter LAB L. plantarum AJ11R and L. pseudomesenteroides BGM3R according to community 16S rRNA gene sequence analysis. The bacterial diversity of those olives was significantly reduced and resembled control fermentations incubated for a longer period of time. Importantly, microbial populations were highly dynamic at the strain level, as indicated by the large variations in AJ11R and BGM3R cell numbers over time and reductions in the numbers of yeast isolates expressing polygalacturonase activity. These findings show the distinct effects of exogenous spoilage and starter microbes on indigenous communities in plant-based food fermentations that result in very different impacts on product quality. IMPORTANCE Food fermentations are subject to tremendous selective pressures resulting in the growth and persistence of a limited number of bacterial and fungal taxa. Although these foods are vulnerable to spoilage by unintended contamination of certain microorganisms, or alternatively, can be

  12. Effects of Exogenous Yeast and Bacteria on the Microbial Population Dynamics and Outcomes of Olive Fermentations

    Science.gov (United States)

    Zaragoza, Jose; Bendiks, Zachary; Tyler, Charlotte; Kable, Mary E.; Williams, Thomas R.; Luchkovska, Yelizaveta; Chow, Elaine; Boundy-Mills, Kyria

    2017-01-01

    ABSTRACT In this study, we examined Sicilian-style green olive fermentations upon the addition of Saccharomyces cerevisiae UCDFST 09-448 and/or Pichia kudriazevii UCDFST09-427 or the lactic acid bacteria (LAB) Lactobacillus plantarum AJ11R and Leuconostoc pseudomesenteroides BGM3R. Olives containing S. cerevisiae UCDFST 09-448, a strain able to hydrolyze pectin, but not P. kudriazevii UCDFST 09-427, a nonpectinolytic strain, exhibited excessive tissue damage within 4 weeks. DNA sequencing of fungal internal transcribed spacer (ITS) regions and comparisons to a yeast-specific ITS sequence database remarkably showed that neither S. cerevisiae UCDFST 09-448 nor P. kudriazevii UCDFST 09-427 resulted in significant changes to yeast species diversity. Instead, Candida boidinii constituted the majority (>90%) of the total yeast present, independent of whether S. cerevisiae or P. kudriazevii was added. By comparison, Lactobacillus species were enriched in olives inoculated with potential starter LAB L. plantarum AJ11R and L. pseudomesenteroides BGM3R according to community 16S rRNA gene sequence analysis. The bacterial diversity of those olives was significantly reduced and resembled control fermentations incubated for a longer period of time. Importantly, microbial populations were highly dynamic at the strain level, as indicated by the large variations in AJ11R and BGM3R cell numbers over time and reductions in the numbers of yeast isolates expressing polygalacturonase activity. These findings show the distinct effects of exogenous spoilage and starter microbes on indigenous communities in plant-based food fermentations that result in very different impacts on product quality. IMPORTANCE Food fermentations are subject to tremendous selective pressures resulting in the growth and persistence of a limited number of bacterial and fungal taxa. Although these foods are vulnerable to spoilage by unintended contamination of certain microorganisms, or alternatively, can

  13. 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...

  14. 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...

  15. 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.

  16. 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

  17. 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.

  18. Methane-Oxidizing Bacteria Shunt Carbon to Microbial Mats at a Marine Hydrocarbon Seep

    Science.gov (United States)

    Paul, Blair G.; Ding, Haibing; Bagby, Sarah C.; Kellermann, Matthias Y.; Redmond, Molly C.; Andersen, Gary L.; Valentine, David L.

    2017-01-01

    The marine subsurface is a reservoir of the greenhouse gas methane. While microorganisms living in water column and seafloor ecosystems are known to be a major sink limiting net methane transport from the marine subsurface to the atmosphere, few studies have assessed the flow of methane-derived carbon through the benthic mat communities that line the seafloor on the continental shelf where methane is emitted. We analyzed the abundance and isotope composition of fatty acids in microbial mats grown in the shallow Coal Oil Point seep field off Santa Barbara, CA, USA, where seep gas is a mixture of methane and CO2. We further used stable isotope probing (SIP) to track methane incorporation into mat biomass. We found evidence that multiple allochthonous substrates supported the rich growth of these mats, with notable contributions from bacterial methanotrophs and sulfur-oxidizers as well as eukaryotic phototrophs. Fatty acids characteristic of methanotrophs were shown to be abundant and 13C-enriched in SIP samples, and DNA-SIP identified members of the methanotrophic family Methylococcaceae as major 13CH4 consumers. Members of Sulfuricurvaceae, Sulfurospirillaceae, and Sulfurovumaceae are implicated in fixation of seep CO2. The mats’ autotrophs support a diverse assemblage of co-occurring bacteria and protozoa, with Methylophaga as key consumers of methane-derived organic matter. This study identifies the taxa contributing to the flow of seep-derived carbon through microbial mat biomass, revealing the bacterial and eukaryotic diversity of these remarkable ecosystems.

  19. 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.

  20. 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.

  1. Nitrate-reducing, sulfide-oxidizing bacteria as microbial oxidants for rapid biological sulfide removal.

    Science.gov (United States)

    De Gusseme, Bart; De Schryver, Peter; De Cooman, Michaël; Verbeken, Kim; Boeckx, Pascal; Verstraete, Willy; Boon, Nico

    2009-01-01

    The emission of hydrogen sulfide into the atmosphere of sewer systems induces the biological production of sulfuric acid, causing severe concrete corrosion. As a possible preventive solution, a microbial consortium of nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) was enriched in a continuously stirred tank reactor in order to develop a biological technique for the removal of dissolved sulfide. The consortium, dominated by Arcobacter sp., was capable of removing 99% of sulfide. Stable isotope fractioning of the sulfide indicated that the oxidation was a biological process. The capacity of the NR-SOB consortium for rapid removal of sulfide was demonstrated by using it as an inoculum in synthetic and real sewage. Removal rates up to 52 mg sulfide-S g VSS(-1) h(-1) were achieved, to our knowledge the highest removal rate reported so far for freshwater species in the absence of molecular oxygen. Further long-term incubation experiments revealed the capacity of the bacteria to oxidize sulfide without the presence of nitrate, suggesting that an oxidized redox reserve is present in the culture.

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Katarína Mlynáriková

    2015-11-01

    Full Text Available 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.

  4. 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.

  5. In-office bacteria test for a microbial monitoring during the conventional and self-ligating orthodontic treatment

    Directory of Open Access Journals (Sweden)

    Mummolo Stefano

    2013-02-01

    Full Text Available Abstract This study investigated the microbial level of Streptococcus mutans and Lactobacillus spp. during an orthodontic treatment, and compare the data with untreated control subjects. Sixty young adult subjects were selected (average 20.5, DS 1.62, among which 40 underwent an orthodontic treatment (20 were treated with self-ligating brackets and 20 with conventional brackets and 20 were controls. Plaque Index, salivary flow and buffering capacity of saliva were assessed before the beginning of the orthodontic treatment. Then the microbial counts were obtained by using an in-office bacteria test. The plaque index (PI increased over time in each group as well as salivary flow, mostly in subjects treated with self-ligating brackets, suggesting a difference between conventional and self-ligating brackets. S.mutans showed a different trend of colonization in the two treated groups, as for subjects treated with conventional brackets it showed the greater value at the early stage of treatment (T1, followed by a decrease at T2. Lactobacillus spp. showed significant increase over time in the two treated groups, respect to the control group. Linear regression analysis showed no significant predictor for the microbial count at T2. The assortment of the various species of bacteria change over time during the orthodontic treatment, and seems to show different trends, depending on the type of orthodontic device. Consequently a periodical microbial monitoring using in-office bacteria tests, seems indicated.

  6. 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)

  7. 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.

  8. 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...

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

    Science.gov (United States)

    Christensen, Sarah C B; Nissen, Erling; Arvin, Erik; Albrechtsen, Hans-Jørgen

    2012-10-15

    Water lice, Asellus aquaticus (isopoda), frequently occur in drinking water distribution systems where they are a nuisance to consumers and water utilities. Whether they are solely an aesthetic problem or also affect the microbial water quality is a matter of interest. We studied the influence of A. 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 (measured as heterotrophic plate counts, HPC) were investigated in microcosms at 7 °C, containing non-sterilised drinking water, drinking water sediment and A. aquaticus collected from a non-chlorinated ground water based drinking water supply system. Concentrations of E. coli, K. pneumoniae and C. jejuni 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 A. aquaticus associated heterotrophic bacteria (>1.8*10(4) CFU per living and >6*10(4) CFU per dead A. aquaticus). A. aquaticus did not serve as an optimised habitat that increased survival of indicators and pathogens, since A. aquaticus associated E. coli, K. pneumoniae and C. jejuni were only measured as long as the bacteria were also present in the water and sediment.

  10. 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'.

  11. Isolation and identification of microorganisms including lactic acid bacteria and their use in microbial deacidification of wines from domestic vineyards.

    Science.gov (United States)

    Drozdz, Iwona; Makarewicz, Malgorzata; Tuszyński, Tadeusz

    2013-01-01

    The aim of this study was to identify various bacteria isolated from grapes and their wines. Additionally we investigated the capacity of lactic acid bacteria for microbiological deacidification of wines produced in Poland. We have identified Oenococcus oeni, Lactobacillus acidophilus and Lactobacillus delbrueckii. During the microbial deacidification process, we observed decreases of total acidity and increases of volatile acidity, with statistically significant changes noted for O. oeni in Marechal Foch and Seyval Blanc, and for Lb. acidophilus in Frontenac. On the other hand, a statistically significant increase in pH was observed in Marechal Foch and Seyval Blanc following deacidification by O. oeni.

  12. 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.

  13. 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.

  14. [Influence of Different Straws Returning with Landfill on Soil Microbial Community Structure Under Dry and Water Farming].

    Science.gov (United States)

    Lan, Mu-ling; Gao, Ming

    2015-11-01

    Based on rice, wheat, corn straw and rape, broad bean green stalk as the research object, using phospholipid fatty acid (PLFA) method, combining principal component analysis method to study the soil microbial quantity, distribution of flora, community structure characteristics under dry and water farming as two different cultivated land use types. The PLFA analysis results showed that: under dry farming, total PLFA quantity ranged 8.35-25.15 nmol x g(-1), showed rape > broad bean > corn > rice > wheat, rape and broad bean significantly increased total PLFA quantity by 1.18 and 1.08 times compared to the treatment without straw; PLFA quantity of bacterial flora in treatments with straws was higher than that without straw, and fungal biomass was significantly increased, so was the species richness of microbial community. Under water faming, the treatments of different straws returning with landfill have improved the PLFA quantity of total soil microbial and flora comparing with the treatment without straw, fungi significantly increased, and species richness of microbial communities value also increased significantly. Total PLFA quantity ranged 4.04-22.19 nmol x g(-1), showed rice > corn > wheat > broad bean > rape, which in rape and broad bean treatments were lower than the treatment without straw; fungal PLFA amount in 5 kinds of straw except broad bean treatment was significantly higher than that of the treatment without straw, bacteria and total PLFA quantity in broad bean processing were significantly lower than those of other treatments, actinomycetes, G+, G- had no significant difference between all treatments; rice, wheat, corn, rape could significantly increase the soil microbial species richness index and dominance index under water faming. The results of principal component analysis showed that broad bean green stalk had the greatest impact on the microbial community structure in the dry soil, rape green stalk and wheat straw had the biggest influence on

  15. Microbiological Aspects of Geothermal Energy: Influence of Microbial Activity on Scaling and Clogging in a Cold Storage

    Science.gov (United States)

    Lerm, Stephanie; Alawi, Mashal; Miethling-Graff, Rona; Vieth, Andrea; Seibt, Andrea; Wolfgramm, Markus; Würdemann, Hilke

    2010-05-01

    that bacteria and their metabolic activities were involved in the decrease of filter endurances. A strong biofilm formation of filamentous sulfur-oxidizing bacteria related to Thiothrix was observed. In the course of the disinfection measure the microbial composition in the process water changed significantly. Thiothrix could not be detected any longer and the biocoenosis in the fluid was dominated now by Flavobacterium, Acidovorax as well as Alcaligenaceae related organisms. In contrast, SRB analyzed by specific dissimilatory sulfite reductase genes were hardly affected by the disinfection measures. However, even if especially SRB are considered as the most important taxonomic group for microbiologically influenced corrosion (MIC), present operational results indicate that scaling and clogging were the predominant processes for the operation of the shallow cold storage in Berlin.

  16. 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.

  17. Influence of sulfhydryl sites on metal binding by bacteria

    Science.gov (United States)

    Nell, Ryan M.; Fein, Jeremy B.

    2017-02-01

    The role of sulfhydryl sites within bacterial cell envelopes is still unknown, but the sites may control the fate and bioavailability of metals. Organic sulfhydryl compounds are important complexing ligands in aqueous systems and they can influence metal speciation in natural waters. Though representing only approximately 5-10% of the total available binding sites on bacterial surfaces, sulfhydryl sites exhibit high binding affinities for some metals. Due to the potential importance of bacterial sulfhydryl sites in natural systems, metal-bacterial sulfhydryl site binding constants must be determined in order to construct accurate models of the fate and distribution of metals in these systems. To date, only Cd-sulfhydryl binding has been quantified. In this study, the thermodynamic stabilities of Mn-, Co-, Ni-, Zn-, Sr- and Pb-sulfhydryl bacterial cell envelope complexes were determined for the bacterial species Shewanella oneidensis MR-1. Metal adsorption experiments were conducted as a function of both pH, ranging from 5.0 to 7.0, and metal loading, from 0.5 to 40.0 μmol/g (wet weight) bacteria, in batch experiments in order to determine if metal-sulfhydryl binding occurs. Initially, the data were used to calculate the value of the stability constants for the important metal-sulfhydryl bacterial complexes for each metal-loading condition studied, assuming a single binding reaction for the dominant metal-binding site type under the pH conditions of the experiments. For most of the metals that we studied, these calculated stability constant values increased significantly with decreasing metal loading, strongly suggesting that our initial assumption was not valid and that more than one type of binding occurs at the assumed binding site. We then modeled each dataset with two distinct site types with identical acidity constants: one site with a high metal-site stability constant value, which we take to represent metal-sulfhydryl binding and which dominates under low

  18. The microbial spectrum of neonatal sepsis in Uganda: recovery of culturable bacteria in mother-infant pairs.

    Science.gov (United States)

    Kiwanuka, Julius; Bazira, Joel; Mwanga, Juliet; Tumusiime, Dickson; Nyesigire, Eunice; Lwanga, Nkangi; Warf, Benjamin C; Kapur, Vivek; Poss, Mary; Schiff, Steven J

    2013-01-01

    Neonatal sepsis in the developing world is incompletely characterized. We seek to characterize the microbial spectrum involved in sepsis and determine the role of maternal transmission by comparing organisms that can be cultured from septic newborn infants and their mothers. From 80 consecutive mother-infant pairs meeting clinical criteria for neonatal sepsis, we collected infant blood and spinal fluid, and maternal blood and vaginal specimens. Identifiable bacteria were recovered from the blood in 32.5% of infants, and from 2.5% of cerebrospinal fluid cultures, for a total of 35% recoverable putative causative agents. Bacteria recovered from vaginal specimens were not concordant with those recovered from infants. Similarly there was no concordance of bacteria recovered from blood and cerebrospinal fluid. We conclude that relying on traditional bacterial culture techniques does not adequately delineate the role of maternal versus environmental sources of neonatal sepsis in this setting. More sensitive molecular approaches will be needed to properly characterize the maternal and environmental microbial community involved in neonatal sepsis in such developing countries.

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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).

  5. 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.

  6. Fabrication of Slippery Lubricant-Infused Porous Surface for Inhibition of Microbially Influenced Corrosion.

    Science.gov (United States)

    Wang, Peng; Zhang, Dun; Lu, Zhou; Sun, Shimei

    2016-01-20

    Microbially influenced corrosion (MIC) accelerates the failure of metal in a marine environment. In this research, slippery lubricant-infused porous surface (SLIPS) was designed on aluminum, and its great potential for inhibiting MIC induced by sulfate-reducing bacteria (SRB) was demonstrated in a simulated marine environment. The inhibition mechanism of SLIPS to MIC was proposed based on its effective roles in the suppression of SRB settlement and isolation effect to corrosive metabolites. The liquid-like property is demonstrated to be the major contributor to the suppression effect of SLIPS to SRB settlement. The effects of environmental factors (static and dynamic conditions) and lubricant type to SRB settlement over SLIPS were also investigated. It was indicated that the as-fabricated SLIPS can inhibit the SRB settlement in both static and dynamic marine conditions, and lubricant type presents a negligible effect on the SRB settlement. These results will provide a series of foundational data for the future practical application of SLIPS in the marine environment, and also a lubricant selecting instruction to construct SLIPS for MIC control.

  7. Characterization of Electricity Generated by Soil in Microbial Fuel Cells and the Isolation of Soil Source Exoelectrogenic Bacteria

    Directory of Open Access Journals (Sweden)

    Yun-Bin Jiang

    2016-11-01

    Full Text Available Soil has been used to generate electrical power in microbial fuel cells (MFCs and exhibited several potential applications. This study aimed to reveal the effect of soil properties on the generated electricity and the diversity of soil source exoelectrogenic bacteria. Seven soil samples were collected across China and packed into air-cathode MFCs to generate electricity over a 270 d period. The Fe(III-reducing bacteria in soil were enriched and sequenced by Illumina pyrosequencing. Culturable strains of Fe(III-reducing bacteria were isolated and identified phylogenetically. Their exoelectrogenic ability was evaluated by polarization measurement. The results showed that soils with higher organic carbon content but lower soil pH generated higher peak voltage and charge. The sequencing of Fe(III-reducing bacteria showed that Clostridia were dominant in all soil samples. At the family level, Clostridiales Family XI. incertae sedis were dominant in soils with lower organic carbon content but higher pH (>8, while Clostridiaceae, Lachnospiraceae and Planococcaceae were dominant in soils with higher organic carbon content but lower pH. The isolated culturable strains were allied phylogenetically to fifteen different species, of which eleven were Clostridium. The others were Robinsoniella peoriensis, Hydrogenoanaerobacterium saccharovorans, Eubacterium contortum and Oscillibacter ruminantium. The maximum power density generated by the isolates in the MFCs ranged from 16.4 to 28.6 mW m-2. We concluded that soil organic carbon content had the most important effect on power generation and that the Clostridiaceae were the dominant exoelectrogenic bacterial group in soil. This study might lead to the discovery of more soil source exoelectrogenic bacteria species.

  8. 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

  9. 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.

  10. Influence of Acetylene on Growth of Sulfate-Respiring Bacteria

    OpenAIRE

    Payne, W J; Grant, M. A.

    1982-01-01

    At a concentration of 20% of the atmosphere of the culture flasks, acetylene inhibited growth and carbon dioxide production by Desulfovibrio desulfuricans and Desulfovibrio gigas. The bacteria did not reduce acetylene to ethylene, and neither acetylene dicarboxylic acid nor ethylene was inhibitory. At 10%, acetylene was partially inhibitory for the desulfovibrios. At 5%, acetylene impeded the rate but did not limit the extent of growth and catabolism of the desulfovibrios. Desulfotomaculum ru...

  11. 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).

  12. 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.

  13. Temporal variability of the microbial food web (viruses to ciliates under the influence of the Black Sea Water inflow (N. Aegean, E. Mediterranean

    Directory of Open Access Journals (Sweden)

    A. GIANNAKOUROU

    2015-01-01

    Full Text Available Τhe entire pelagic microbial food web was studied during the winter-spring period in the frontal area of the North Aegean Sea. Abundance of viruses, heterotrophic bacteria, cyanobacteria, auto- and hetero-trophic flagellates, and ciliates, as well as bacterial production, were measured at three stations (MD1, MD2, MD3 situated along a N-S transect between the area directly influenced by the inflowing Black Sea water and the area covered by the Levantine water. Samples were collected in December 2009, and January, March, April, and May 2011. Station MD1 exhibited the highest values of abundance and integrated biomass of all microbial groups and bacterial production during all months, and MD3 the lowest. Bacteria dominated the total integrated biomass at all stations and months, followed by cyanobacteria, auto-, hetero-trophic flagellates and ciliates. On a temporal scale, the microbial food web was less important in March as all microbial parameters at all stations showed the lowest values. After the phytoplankton bloom in March, the heterotrophic part of the microbial food web (mainly strongly increased, though the intensity of the phenomenon was diminished from North to South. Pico-sized plankton was found to be heterotrophic whereas nanoplankton was autotrophic. It seems that the influence of the Black Sea water on station MD1, permanent throughout the study period of early winter to late spring, was reflected in all microbial populations studied, and produced a more productive pelagic food web system, with potential consequences for the upper trophic levels.

  14. 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

    2007-01-01

    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 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 S2O32−). 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

  15. Assessment of tillage systems in organic farming: influence of soil structure on microbial biomass. First results

    OpenAIRE

    Vian, Jean François; Peigné, Joséphine; Chaussod, Rémi; Roger-Estrade, Jean

    2007-01-01

    Soil tillage modifies environmental conditions of soil microorganisms and their ability to release nitrogen. We compare the influence of reduced tillage (RT) and mouldboard ploughing (MP) on the soil microbial functioning in organic farming. In order to connect soil structure generated by these tillage systems on the soil microbial biomass we adopt a particular sampling scheme based on the morphological characterisation of the soil structure by the description of the soil profile. This method...

  16. Modeling how soluble microbial products (SMP) support heterotrophic bacteria in autotroph-based biofilms

    DEFF Research Database (Denmark)

    Merkey, Brian; Rittmann, Bruce E.; Chopp, David L.

    2009-01-01

    . In this paper, we develop and use a mathematical model to describe a model biofilm system that includes autotrophic and heterotrophic bacteria and the key products produced by the bacteria. The model combines the methods of earlier multi-species models with a multi-component biofilm model in order to explore......Multi-species biofilm modeling has been used for many years to understand the interactions between species in different biofilm systems, but the complex symbiotic relationship between species is sometimes overlooked, because models do not always include all relevant species and components...

  17. [Influence endophytic bacteria to promote plants growth in stress conditions].

    Science.gov (United States)

    Napora, Anna; Kacprzak, Małgorzata; Nowak, Kamil; Grobelak, Anna

    2015-01-01

    The growth of plants under stress conditions is often assisted by microorganisms colonizing the rhizosphere (the root zone of the highest microbial activity). One of the most important bacterial groups to encourage the growth of plants (PGPB) are endophytes. These microorganisms penetrate living cells of plants and there they lead the microbiological activity as endosymbionts. These microorganisms can effectively promote the growth of plants under stress conditions and stimulate biochemical activities: nitrogen fixation, production of growth hormones (auxins, cytokinins and gibberellins), reduction of the high concentration of ethylene as well as facilitation of the collection plant minerals and water. This paper is an attempt to summarize the current state of knowledge about the biochemical activity of bacterial endophytes.

  18. Influence of Panax ginseng Continuous Cropping on Metabolic Function of Soil Microbial Communities

    Institute of Scientific and Technical Information of China (English)

    YING Yi-xin; DING Wan-long; ZHOU Ying-qun; LI Yong

    2012-01-01

    Objective To investigate the influence of Panax ginseng continuous cropping on the carbon substrate metabolic activity of microbes in soils sampled from Dafang,Huangni,and Wulidi in Jilin Province,China.Methods Soil metabolisms of soil communities were characterized by community level physiological profiles using BIOLOGTM EcoPlate.Results Soils sampled from the three sites were analyzed and their metabolic activities were compared.Principal component analysis explored the significant variance in metabolic function of microbial communities in soils,though the Shannon index and the evenness index of them were similar.Futhermore,two principal components(PC1 and PC2),which contributed 67.83% and 10.78% of total variance,were extracted respectively.And also,substrates significantly correlated with PC1 and PC2 at the three sampling sites were identified.Conclusion Characteristic of soil is the primary factor influencing microbial communities,and P.ginseng continuous cropping has significant influence on microbial community.Though soil samples show similar microbial metabolic profiles,microbial communities in rhizosphere soil are changed obviously during the cultivation of P.ginseng,which would finally result in the unbalance of microbial community.Phytopathogens would gradually be the predominants in rhizosphere soil and make P.ginseng sick.

  19. 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

  20. 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…

  1. 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

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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 ...

  10. Influence of earthworm activity on microbial communities related with the degradation of persistent pollutants.

    Science.gov (United States)

    Natal-da-Luz, Tiago; Lee, Iwa; Verweij, Rudo A; Morais, Paula V; Van Velzen, Martin J M; Sousa, José Paulo; Van Gestel, Cornelis A M

    2012-04-01

    Earthworms may promote the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in soil, but the mechanism through which they exert such influence is still unknown. To determine if the stimulation of PAH degradation by earthworms is related to changes in microbial communities, a microcosm experiment was conducted consisting of columns with natural uncontaminated soil covered with PAH-contaminated dredge sediment. Columns without and with low and high Eisenia andrei densities were prepared. Organic matter and PAH content, microbial biomass, and dehydrogenase activity (DHA) were measured in soil and sediment over time. Biolog Ecoplate™ and polymerase chain reaction using denaturing gradient gel electrophoresis were used to evaluate changes in metabolic and structural diversity of the microbial community, respectively. Earthworm activity promoted PAH degradation in soil, which was significant for biphenyl, benzo[a]pyrene, and benzo[e]pyrene. Microbial biomass and DHA activity generally did not change over the experiment. Earthworm activity did change microbial community structure, but this did not affect its functioning in terms of carbon substrate consumption. Results suggest no relationship between changes in the microbial community by earthworm activity and increased PAH disappearance. The role of shifts in soil microbial community structure induced by earthworms in PAH removal needs further investigation.

  11. Cross-kingdom amplification using Bacteria-specific primers: Complications for studies of coral microbial ecology

    Science.gov (United States)

    Galkiewicz, J.P.; Kellogg, C.A.

    2008-01-01

    PCR amplification of pure bacterial DNA is vital to the study of bacterial interactions with corals. Commonly used Bacteria-specific primers 8F and 27F paired with the universal primer 1492R amplify both eukaryotic and prokaryotic rRNA genes. An alternative primer set, 63F/1542R, is suggested to resolve this problem. Copyright ?? 2008, American Society for Microbiology. All Rights Reserved.

  12. 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.

  13. 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.

  14. 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.

  15. Microbial cargo: do bacteria on symbiotic propagules reinforce the microbiome of lichens?

    Science.gov (United States)

    Aschenbrenner, Ines Aline; Cardinale, Massimiliano; Berg, Gabriele; Grube, Martin

    2014-12-01

    According to recent research, bacteria contribute as recurrent associates to the lichen symbiosis. Yet, the variation of the microbiomes within species and across geographically separated populations remained largely elusive. As a quite common dispersal mode, lichens evolved vertical transmission of both fungal and algal partners in specifically designed mitotic propagules. Bacteria, if co-transmitted with these symbiotic propagules, could contribute to a geographical structure of lichen-associated microbiomes. The lung lichen was sampled from three localities in eastern Austria to analyse their associated bacterial communities by bar-coded pyrosequencing, network analysis and fluorescence in situ hybridization. For the first time, bacteria were documented to colonize symbiotic propagules of lichens developed for short-distance transmission of the symbionts. The propagules share the overall bacterial community structure with the thalli at class level, except for filamentous Cyanobacteria (Nostocophycideae), and with Alphaproteobacteria as predominant group. All three sampling sites share a core fraction of the microbiome. Bacterial communities of lichen thalli from the same sampling site showed higher similarity than those of distant populations. This variation and the potential co-dispersal of a microbiome fraction with structures of the host organism contribute new aspects to the 'everything is everywhere' hypothesis.

  16. Chromium(VI) Bioremoval by Pseudomonas Bacteria: Role of Microbial Exudates for Natural Attenuation and Biotreatment of Cr(VI) Contamination

    Energy Technology Data Exchange (ETDEWEB)

    N Mercan Dogan; C Kantar; S Gulcan; C Dodge; B Coskun Yilmaz; M Ali Mazmanci

    2011-12-31

    Laboratory batch and column experiments were conducted to investigate the role of microbial exudates, e.g., exopolymeric substance (EPS) and alginic acid, on microbial Cr(VI) reduction by two different Pseudomonas strains (P. putida P18 and P. aeuroginosa P16) as a method for treating subsurface environment contaminated with Cr(VI). Our results indicate that microbial exudates significantly enhanced microbial Cr(VI) reduction rates by forming less toxic and highly soluble organo-Cr(III) complexes despite the fact Cr(III) has a very low solubility under the experimental conditions studied (e.g., pH 7). The formation of soluble organo-Cr(III) complexes led to the protection of the cells and chromate reductases from inactivation. In systems with no organic ligands, soluble organo-Cr(III) end products were formed between Cr(III) and the EPS directly released by bacteria due to cell lysis. Our results also provide evidence that cell lysis played an important role in microbial Cr(VI) reduction by Pseudomonas bacteria due to the release of constitutive reductases that intracellularly and/or extracellularly catalyzed the reduction of Cr(VI) to Cr(III). The overall results highlight the need for incorporation of the release and formation of organo-Cr(III) complexes into reactive transport models to more accurately design and monitor in situ microbial remediation techniques for the treatment of subsurface systems contaminated with Cr(VI).

  17. Chromium(VI) bioremoval by pseudomonas bacteria: role of microbial exudates for natural attenuation and biotreatment of Cr(VI) contamination

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, N.M.; Dodge, C.; Kantar, C.; Gulcan, S.; Yilmaz, B.C.; Mazmanci, M.A.

    2011-02-14

    Laboratory batch and column experiments were conducted to investigate the role of microbial exudates, e.g., exopolymeric substance (EPS) and alginic acid, on microbial Cr(VI) reduction by two different Pseudomonas strains (P. putida P18 and P. aeuroginosa P16) as a method for treating subsurface environment contaminated with Cr(VI). Our results indicate that microbial exudates significantly enhanced microbial Cr(VI) reduction rates by forming less toxic and highly soluble organo-Cr(III) complexes despite the fact Cr(III) has a very low solubility under the experimental conditions studied (e.g., pH 7). The formation of soluble organo-Cr(III) complexes led to the protection of the cells and chromate reductases from inactivation. In systems with no organic ligands, soluble organo-Cr(III) end products were formed between Cr(III) and the EPS directly released by bacteria due to cell lysis. Our results also provide evidence that cell lysis played an important role in microbial Cr(VI) reduction by Pseudomonas bacteria due to the release of constitutive reductases that intracellularly and/or extracellularly catalyzed the reduction of Cr(VI) to Cr(III). The overall results highlight the need for incorporation of the release and formation of organo-Cr(III) complexes into reactive transport models to more accurately design and monitor in situ microbial remediation techniques for the treatment of subsurface systems contaminated with Cr(VI).

  18. 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

  19. The influence of fat and monoacylglycerols on growth of spore-forming bacteria in processed cheese.

    Science.gov (United States)

    Hauerlandová, Iva; Lorencová, Eva; Buňka, František; Navrátil, Jan; Janečková, Kristýna; Buňková, Leona

    2014-07-16

    Highly undesirable microbial contaminants of processed cheese are endospore-forming bacteria of the genera Bacillus and Clostridium. Survival of Bacillus subtilis, B. cereus, Clostridium butyricum and C. sporogenes was examined in model processed cheese samples supplemented with monoacylglycerols. In processed cheese samples, monoacylglycerols of undecanoic, undecenoic, lauric and adamantane-1-carboxylic acid at concentration of 0.15% w/w prevented the growth and multiplication of both Bacillus species throughout the storage period. The two species of Clostridium were less affected by monoacylglycerols in processed cheese samples and only partial inhibition was observed. The effect of milk fat content on microbial survival in processed cheese was also evaluated. The growth of Bacillus sp. was affected by the fat level of processed cheese while population levels of Clostridium sp. did not differ in processed cheese samples with 30, 40 and 50% fat in dry matter.

  20. 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.

  1. Microbial fouling community analysis of the cooling water system of a nuclear test reactor with emphasis on sulphate reducing bacteria.

    Science.gov (United States)

    Balamurugan, P; Joshi, M Hiren; Rao, T S

    2011-10-01

    Culture and molecular-based techniques were used to characterize bacterial diversity in the cooling water system of a fast breeder test reactor (FBTR). Techniques were selected for special emphasis on sulphate-reducing bacteria (SRB). Water samples from different locations of the FBTR cooling water system, in addition to biofilm scrapings from carbon steel coupons and a control SRB sample were characterized. Whole genome extraction of the water samples and SRB diversity by group specific primers were analysed using nested PCR and denaturing gradient gel electrophoresis (DGGE). The results of the bacterial assay in the cooling water showed that the total culturable bacteria (TCB) ranged from 10(3) to 10(5) cfu ml(-1); iron-reducing bacteria, 10(3) to 10(5) cfu ml(-1); iron oxidizing bacteria, 10(2) to 10(3) cfu ml(-1) and SRB, 2-29 cfu ml(-1). However, the counts of the various bacterial types in the biofilm sample were 2-3 orders of magnitude higher. SRB diversity by the nested PCR-DGGE approach showed the presence of groups 1, 5 and 6 in the FBTR cooling water system; however, groups 2, 3 and 4 were not detected. The study demonstrated that the PCR protocol influenced the results of the diversity analysis. The paper further discusses the microbiota of the cooling water system and its relevance in biofouling.

  2. 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

  3. 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.

  4. 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.

  5. Microbial diversity of vermicompost bacteria that exhibit useful agricultural traits and waste management potential.

    Science.gov (United States)

    Pathma, Jayakumar; Sakthivel, Natarajan

    2012-01-01

    Vermicomposting is a non-thermophilic, boioxidative process that involves earthworms and associated microbes. This biological organic waste decomposition process yields the biofertilizer namely the vermicompost. Vermicompost is a finely divided, peat like material with high porosity, good aeration, drainage, water holding capacity, microbial activity, excellent nutrient status and buffering capacity thereby resulting the required physiochemical characters congenial for soil fertility and plant growth. Vermicompost enhances soil biodiversity by promoting the beneficial microbes which inturn enhances plant growth directly by production of plant growth-regulating hormones and enzymes and indirectly by controlling plant pathogens, nematodes and other pests, thereby enhancing plant health and minimizing the yield loss. Due to its innate biological, biochemical and physiochemical properties, vermicompost may be used to promote sustainable agriculture and also for the safe management of agricultural, industrial, domestic and hospital wastes which may otherwise pose serious threat to life and environment.

  6. Isolation and Characterization of Methyl Parathion-degrading Bacteria Based on Microbial Sensor Construction

    Directory of Open Access Journals (Sweden)

    GENG Fang-fang

    2014-12-01

    Full Text Available Methyl parathion (MP, a kind of typical organophosphates pesticides (OPs, is widely used as agricultural insecticides. However, due to their neurotoxic effects on humans, the elimination of OPs has become increasingly important. Microbial sensors are consisted of biological components and transducers. Owing to their attractive advantages including low cost, easy of miniaturization and excellent selectivity, they have been widely used for environmental analysis. In this paper, four novel bacterial strains capable of utilizing methyl parathion as the sole carbon source were isolated from pesticide contaminated soils. These four isolates were identified based on morphological characteristics and 16S rRNA gene sequences analysis, and their capability of degrading methyl parathion were investigated by high performance liquid chromatography. The highest degrading efficiency strain was selected for further study of degrading mechanism. The results indicated that degradation rate of these four strains were all over 78% after incubation at 30 ℃, pH 7.0 for 7 d with the original concentration of methyl parathion 50 mg·L-1. The highest degradation rate was up to 100%. 16S rRNA gene sequences indicated that strain MP-6 was affiliated into the genus klebsiella. The LC-MS results indicated that methyl parathion was hydrolyzed to dimethyl thiophosphoric acid and p-nitrophenol by MP-6. A little of p-nitrophenol molecules could be further metabolized to 4-nitrocatechol and 1, 2, 4-benzenetrio. The results indicated that based on detecting the potential signal of intermediate product p-nitrophenol, the strain MP-6 could be used to construct microbial sensors for determination of organophosphorus pesticides in environment.

  7. Bioremediation of Agro-Based Pulp Mill Effluent by Microbial Consortium Comprising Autochthonous Bacteria

    Directory of Open Access Journals (Sweden)

    Virendra Kumar

    2012-01-01

    Full Text Available Small-scale agro-based pulp and paper mills are characterized as highly polluting industries. These mills use Kraft pulping process for paper manufacturing due to which toxic lignified chemicals are released into the environment. Lack of infrastructure, technical manpower, and research and development facilities restricts these mills to recover these chemicals. Therefore, the chemical oxygen demand (COD of the emanating stream is quite high. For solving the above problem, four bacteria were isolated from the premises of agro-based pulp and paper mill which were identified as species of Pseudomonas, Bacillus, Pannonibacter, and Ochrobacterum. These bacteria were found capable of reducing COD up to 85%–86.5% in case of back water and 65-66% in case of back water : black liquor (60 : 40, respectively, after acclimatization under optimized conditions (pH 6.8, temperature 35°C, and shaking 200 rpm when the wastewater was supplemented with nitrogen and phosphorus as trace elements.

  8. CONDITIONING MICROBIAL PRODUCTS CONTAINING LACTIC BACTERIA WITH ORGANIC AND INORGANIC SUPPORTS FOR USE IN ANIMAL FEEDING

    Directory of Open Access Journals (Sweden)

    T VINTILĂ

    2013-12-01

    Full Text Available The stability in real time of three strains of lactic bacteria (Lactobacillus acidophilus, Lactobacillus plantarum, Enterococcus faecium mixed with different excipients was evaluated during a 6-months period. The excipients studied were: zeolite, calcium carbonate, perlite ceramic, wheat bran and Carboxymethyl cellulose (CMC. A part of liquid cultures and excipients mixtures were dried (12- 14% humidity and other part were sealed in plastic bags with over 70% humidity and preserved at +4oC. The cells were activated periodically by suspending aliquots from wet and dry products in 0.9% saline solution. The viability of lactic bacteria was evaluated by cultivation of diluted suspensions in MRS plates. The number of viable lactic cells is decreasing very slowly, or remains constant in calcium carbonate, ceramics and CMC dry products for al strains. In the case of zeolite, the viability of Lb. acidophilus and Lb. plantarum decrease to 0 in the first month, and the viability of Ec. faecium decrease 20 times in 6 months. As for wet products, the number of viable cells is increasing in the first 30 days for calcium carbonate and in the first 60 days for wheat bran. The numbers of viable cells decrease in both wet products, reaching values close to the viability in fresh products after 6 months of storage at +4oC.

  9. 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

  10. Influence of Environmental Stressors on the Physiology of Pollutant Degrading Bacteria

    DEFF Research Database (Denmark)

    Svenningsen, Nanna Bygvraa

    of model degrader bacteria to nutrient- and oxidative stress, two highly relevant stress scenarios in natural environments, and at evaluating the impact of these environmental stress conditions on catabolic gene expression. The results suggest that environmental bacteria, here represented by the toluene......Bacteria and other microorganisms play an important role for removal of pollutants released into the environment, either deliberately or accidentally. In particular, soils are reservoirs for microorganisms carrying the catalytic potential for breakdown of otherwise toxic and often recalcitrant...... to expression of catabolic genes. Hence, even though environmental bacteria are able to deal with many stressful situations, environmental stressors can be bottlenecks for pollutant degradation by influencing directly on the level of catabolic gene expression. Finally the study investigated whether findings...

  11. [Influence of milking technique, milking hygiene and environmental hygiene parameters on the microbial contamination of milking machines].

    Science.gov (United States)

    Feldmann, M; Zimmermann, A; Hoedemaker, M

    2006-07-01

    It was the aim of this study to investigate the effect of various factors of the milking technique, milking hygiene and environment on microbial contamination of the milking machine. In 31 dairy herds, the degree of bacterial contamination was examined by taking swabs at four locations (teat cup liner, claw, short and long milk tube) before the milking procedure was started using a standardized protocol (DIN ISO 6887-1:1999). Furthermore, the total germ count was determined in the first milk entering the bulk tank as well as in the bulk tank milk following milking. For each farm, the quality of the milking process and the condition of the milking machine as well as of various environmental factors were recorded. A subjective evaluation of the status of the milking cluster or other parts of the milking machine ("good" or "moderate-poor") gave more information about bacterial contamination than the determination of age and type of material used. A temperature of the rinsing water of teat cleaning before milking or of postmilking teat disinfection did not affect the contamination of the milking machine and the bulk tank milk with environmental bacteria. Furthermore, type of bedding material affected bacterial contamination of milking clusters and bulk tank milk. In conclusion, our results suggest that the microbial contamination of the milking machine is not only influenced by the sanitation pro-

  12. 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

  13. Microbial profiling of cpn60 universal target sequences in artificial mixtures of vaginal bacteria sampled by nylon swabs or self-sampling devices under different storage conditions.

    Science.gov (United States)

    Schellenberg, John J; Oh, Angela Yena; Hill, Janet E

    2017-05-01

    The vaginal microbiome is increasingly characterized by deep sequencing of universal genes. However, there are relatively few studies of how different specimen collection and sample storage and processing influence these molecular profiles. Here, we evaluate molecular microbial community profiles of samples collected using the HerSwab™ self-sampling device, compared to nylon swabs and under different storage conditions. In order to minimize technical variation, mixtures of 11 common vaginal bacteria in simulated vaginal fluid medium were sampled and DNA extracts prepared for massively parallel sequencing of the cpn60 universal target (UT). Three artificial mixtures imitating commonly observed vaginal microbiome profiles were easily distinguished and proportion of sequence reads correlated with the estimated proportion of the organism added to the artificial mixtures. Our results indicate that cpn60 UT amplicon sequencing quantifies the proportional abundance of member organisms in these artificial communities regardless of swab type or storage conditions, although some significant differences were observed between samples that were stored frozen and thawed prior to DNA extraction, compared to extractions from samples stored at room temperature for up to 7days. Our results indicate that an on-the-market device developed for infectious disease diagnostics may be appropriate for vaginal microbiome profiling, an approach that is increasingly facilitated by rapidly dropping deep sequencing costs.

  14. 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

  15. 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.

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

    Directory of Open Access Journals (Sweden)

    Ana L. Freire

    2016-04-01

    Full Text Available 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.

  17. 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.

  18. 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...

  19. 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.

  20. 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

  1. Microbial abundance and community composition influence production performance in a low-temperature petroleum reservoir.

    Science.gov (United States)

    Li, Guoqiang; Gao, Peike; Wu, Yunqiang; Tian, Huimei; Dai, Xuecheng; Wang, Yansen; Cui, Qingfeng; Zhang, Hongzuo; Pan, Xiaoxuan; Dong, Hanping; Ma, Ting

    2014-05-06

    Enhanced oil recovery using indigenous microorganisms has been successfully applied in the petroleum industry, but the role of microorganisms remains poorly understood. Here, we investigated the relationship between microbial population dynamics and oil production performance during a water flooding process coupled with nutrient injection in a low-temperature petroleum reservoir. Samples were collected monthly over a two-year period. The microbial composition of samples was determined using 16S rRNA gene pyrosequencing and real-time quantitative polymerase chain reaction analyses. Our results indicated that the microbial community structure in each production well microhabitat was dramatically altered during flooding with eutrophic water. As well as an increase in the density of microorganisms, biosurfactant producers, such as Pseudomonas, Alcaligenes, Rhodococcus, and Rhizobium, were detected in abundance. Furthermore, the density of these microorganisms was closely related to the incremental oil production. Oil emulsification and changes in the fluid-production profile were also observed. In addition, we found that microbial community structure was strongly correlated with environmental factors, such as water content and total nitrogen. These results suggest that injected nutrients increase the abundance of microorganisms, particularly biosurfactant producers. These bacteria and their metabolic products subsequently emulsify oil and alter fluid-production profiles to enhance oil recovery.

  2. 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.

  3. Microbially induced separation of quartz from hematite using sulfate reducing bacteria.

    Science.gov (United States)

    Prakasan, M R Sabari; Natarajan, K A

    2010-07-01

    Cells and metabolic products of Desulfovibrio desulfuricans were successfully used to separate quartz from hematite through environmentally benign microbially induced flotation. Bacterial metabolic products such as extracellular proteins and polysaccharides were isolated from both unadapted and mineral-adapted bacterial metabolite and their basic characteristics were studied in order to get insight into the changes brought about on bioreagents during adaptation. Interaction between bacterial cells and metabolites with minerals like hematite and quartz brought about significant surface-chemical changes on both the minerals. Quartz was rendered more hydrophobic, while hematite became more hydrophilic after biotreatment. The predominance of bacterial polysaccharides on interacted hematite and of proteins on quartz was responsible for the above surface-chemical changes, as attested through adsorption studies. Surface-chemical changes were also observed on bacterial cells after adaptation to the above minerals. Selective separation of quartz from hematite was achieved through interaction with quartz-adapted bacterial cells and metabolite. Mineral-specific proteins secreted by quartz-adapted cells were responsible for conferment of hydrophobicity on quartz resulting in enhanced separation from hematite through flotation.

  4. 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.

  5. Microbial community shifts influence patterns in tropical forest nitrogen fixation.

    Science.gov (United States)

    Reed, Sasha C; Townsend, Alan R; Cleveland, Cory C; Nemergut, Diana R

    2010-10-01

    The role of biodiversity in ecosystem function receives substantial attention, yet despite the diversity and functional relevance of microorganisms, relationships between microbial community structure and ecosystem processes remain largely unknown. We used tropical rain forest fertilization plots to directly compare the relative abundance, composition and diversity of free-living nitrogen (N)-fixer communities to in situ leaf litter N fixation rates. N fixation rates varied greatly within the landscape, and 'hotspots' of high N fixation activity were observed in both control and phosphorus (P)-fertilized plots. Compared with zones of average activity, the N fixation 'hotspots' in unfertilized plots were characterized by marked differences in N-fixer community composition and had substantially higher overall diversity. P additions increased the efficiency of N-fixer communities, resulting in elevated rates of fixation per nifH gene. Furthermore, P fertilization increased N fixation rates and N-fixer abundance, eliminated a highly novel group of N-fixers, and increased N-fixer diversity. Yet the relationships between diversity and function were not simple, and coupling rate measurements to indicators of community structure revealed a biological dynamism not apparent from process measurements alone. Taken together, these data suggest that the rain forest litter layer maintains high N fixation rates and unique N-fixing organisms and that, as observed in plant community ecology, structural shifts in N-fixing communities may partially explain significant differences in system-scale N fixation rates.

  6. 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

  7. Modeling the Influence of Transport on Chemical Reactivity in Microbial Membranes: Mineral Precipitation/Dissolution Reactions.

    Science.gov (United States)

    Felmy, A. R.; Liu, C.; Clark, S.; Straatsma, T.; Rustad, J.

    2003-12-01

    It has long been known that microorganisms can alter the chemical composition of their immediate surroundings and influence such processes as ion uptake or adsorption and mineral precipitation dissolution. However, only recently have molecular imaging and molecular modeling capabilities been developed that begin to shed light on the nature of these processes at the nm to um scale at the surface of bacterial membranes. In this presentation we will show the results of recent molecular simulations of microbial surface reactions and describe our efforts to develop accurate non-equilibrium thermodynamic models for the microbial surface that can describe ion uptake and surface induced mineral precipitation. The thermodynamic models include the influence of the bacterial electrical double layer on the uptake of ions from solution and the removal, or exclusion, of ions from the surface of the cell, non-equilibrium diffusion and chemical reaction within the membrane, as well as a new thermodynamic approach to representing ion activities within the microbial membrane. In the latter case, the variability in the water content within the microbial membrane has a significant influence on the calculated mineral saturation indices. In such cases, we will propose the use of recently developed mixed solvent-electrolyte formalisms. Recent experimental data for mixed-solvent electrolyte systems will also be presented to demonstrate the potential impact of the variable water content on calculated ion activities within the membrane.

  8. 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.

  9. 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.

  10. [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.

  11. Manduca sexta gloverin binds microbial components and is active against bacteria and fungi.

    Science.gov (United States)

    Xu, Xiao-Xia; Zhong, Xue; Yi, Hui-Yu; Yu, Xiao-Qiang

    2012-10-01

    Hyalophora gloveri gloverin is a glycine-rich and heat stable antimicrobial protein with activity mainly against Escherichia coli. However, Spodoptera exigua gloverin is active against a Gram-positive bacterium but inactive against E. coli. In this study, we investigated expression profile, binding ability and antimicrobial activity of Manduca sexta gloverin (MsGlv). Msglv transcript was detected in several tissues of naïve larvae with higher levels in the midgut and testis. Expression of Msglv mRNA in larvae was up-regulated by active Spätzle-C108 and peptidoglycans (PGs) of E. coli and Staphylococcus aureus, and the activation was blocked by pre-injection of antibody to M. sexta Toll, suggesting that Msglv expression is regulated by the Toll-Spätzle pathway. Recombinant MsGlv bound to the O-specific antigen and outer core carbohydrate of lipopolysaccharide (LPS), Gram-positive lipoteichoic acid (LTA) and PG, and laminarin, but not to E. coli PG or mannan. MsGlv was active against Bacillus cereus, Saccharomyces cerevisiae and Cryptococcus neoformans, but was almost inactive against E. coli and S. aureus. Our results suggest that gloverins are active against some bacteria and fungi.

  12. Plant and bird presence strongly influences the microbial communities in soils of Admiralty Bay, Maritime Antarctica.

    Directory of Open Access Journals (Sweden)

    Lia C R S Teixeira

    Full Text Available Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing relatively large changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies, Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific.

  13. Production of biosurfactant from Bacillus licheniformis for microbial enhanced oil recovery and inhibition the growth of sulfate reducing bacteria

    Directory of Open Access Journals (Sweden)

    H.S. El-Sheshtawy

    2015-06-01

    Full Text Available In this study, the bacterium Bacillus licheniformis has been isolated from oil reservoir; the ability of this bacterium to produce a biosurfactant was detected. Surface properties of the produced biosurfactant were confirmed by determining the emulsification power as well as surface and interfacial tension. The crude biosurfactant has been extracted from supernatant culture growth, and the yield of crude biosurfactant was about 1 g/l. Also, chemical structure of the produced biosurfactant was confirmed using FTIR analysis. Results revealed that, the emulsification power has been increased up to 96% and the surface tension decreased from 72 of distilled water to 36 mN/m after 72 h of incubation. The potential application of this bacterial species in microbial-enhanced oil recovery (MEOR was investigated. The percent of oil recovery was 16.6% upon application in a sand pack column designed to stimulate an oil recovery. It also showed antimicrobial activity against the growth of different strains of SRB (sulfate reducing bacteria. Results revealed that a complete inhibition of SRB growth using 1.0% crude biosurfactant is achieved after 3 h.

  14. 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.

  15. 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.

  16. Microbial ecology of the salmon necrobiome: evidence salmon carrion decomposition influences aquatic and terrestrial insect microbiomes.

    Science.gov (United States)

    Pechal, Jennifer L; Benbow, M Eric

    2016-05-01

    Carrion decomposition is driven by complex relationships that affect necrobiome community (i.e. all organisms and their genes associated with a dead animal) interactions, such as insect species arrival time to carrion and microbial succession. Little is understood about how microbial communities interact with invertebrates at the aquatic-terrestrial habitat interface. The first objective of the study was to characterize internal microbial communities using high-throughput sequencing of 16S rRNA gene amplicons for aquatic insects (three mayfly species) in streams with salmon carcasses compared with those in streams without salmon carcasses. The second objective was to assess the epinecrotic microbial communities of decomposing salmon carcasses (Oncorhynchus keta) compared with those of terrestrial necrophagous insects (Calliphora terraenovae larvae and adults) associated with the carcasses. There was a significant difference in the internal microbiomes of mayflies collected in salmon carcass-bearing streams and in non-carcass streams, while the developmental stage of blow flies was the governing factor in structuring necrophagous insect internal microbiota. Furthermore, the necrophagous internal microbiome was influenced by the resource on which the larvae developed, and changes in the adult microbiome varied temporally. Overall, these carrion subsidy-driven networks respond to resource pulses with bottom-up effects on consumer microbial structure, as revealed by shifting communities over space and time.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. The determination of the real nano-scale sizes of bacteria in chernozem during microbial succession by means of hatching of a soil in aerobic and anaerobic conditions

    Science.gov (United States)

    Gorbacheva, M.

    2012-04-01

    M.A. Gorbacheva,L.M. Polyanskaya The Faculty of Soil Science, Moscow State University, Leninskie Gory, GSP-1, Moscow,119991,Russia In recent years there's been particular attention paid to the smallest life's forms- bacteria which size can be measured in nanometer. These are the forms of bacteria with diameter of 5-200 nm. Theoretical calculations based on the content of the minimum number of DNA, enzyme, lipids in and ribosome in cells indicates impossibility of existence of a living cells within diameter less than 300 nm. It is theoretically possible for a living cell to exist within possible diameter of approximately 140 nm. Using a fluorescence microscope there's been indicated in a number of samples from lakes, rivers, soil, snow and rain water that 200 nm is the smallest diameter of a living cell. Supposingly, such a small size of bacteria in soil is determined by natural conditions which limit their development by nutritious substances and stress-factors. Rejuvenescence of nanobacteria under unfavourable natural conditions and stress-factors is studied in laboratory environment. The object of the current study has become the samples of typical arable chernozem of the Central Chernozem State Biosphere Reserve in Kursk. The detailed morphological description of the soil profile and its basic analytical characteristics are widely represented in scientific publications. The soil is characterized by a high carbon content which makes up 3,96% ,3,8% , and 2,9% for the upper layers of the A horizon, and 0,79% for the layer of the B horizon. A microbial succession was studied under aerobic and anaerobic conditions by means of experiments with microcosms in upper A horizons and B horizon of a chernozem. The final aim is to identify the cells size of bacteria in aerobic and anaerobic soil conditions in chernozem during the microbial succession, by dampening and application of chitin by means of «cascade filtration» method. The study of the microcosms is important for

  2. Survival of introduced phosphate-solubilizing bacteria (PSB) and their impact on microbial community structure during the phytoextraction of Cd-contaminated soil.

    Science.gov (United States)

    Jeong, Seulki; Moon, Hee Sun; Shin, Doyun; Nam, Kyoungphile

    2013-12-15

    This study was conducted to investigate whether or not phosphate-solubilizing bacteria (PSB) as a kind of plant growth promoting rhizobacteria enhance the uptake of Cd by plants. In addition, the effect of PSB augmentation during phytoextraction on the microbial community of indigenous soil bacteria was also studied. In the initial Cd-contaminated soil, the major phyla were Proteobacteria (35%), Actinobacteria (38%) and Firmicutes (8%). While Proteobacteria were dominant at the second and sixth week (41 and 54%, respectively) in inoculated soil, Firmicutes (mainly belonging to the Bacilli class-61%), dramatically increased in the eight-week soil. For the uninoculated soil, the proportion of α-Proteobacteria increased after eight weeks (32%). Interestingly, Actinobacteria class, which was originally present in the soil (37%), seemed to disappear during phytoremediation, irrespective of whether PSB was inoculated or not. Cluster analysis and Principal Component Analysis revealed that the microbial community of eight-week inoculated soil was completely separated from the other soil samples, due to the dramatic increase of Bacillus aryabhattai. These findings revealed that it took at least eight weeks for the inoculated Bacillus sp. to functionally adapt to the introduced soil, against competition with indigenous microorganisms in soil. An ecological understanding of interaction among augmented bacteria, plant and indigenous soil bacteria is needed, for proper management of phytoextraction.

  3. Microbial dynamics in a glycolate fed biogas reactor influenced by abiotic parameters

    OpenAIRE

    Reinert, Susann

    2015-01-01

    Much research was performed in order to find alternative energy sources. In the new concept presented in this thesis, methane was produced by a microbial consortium which is fed only by glycolate excreted by photosynthetic algae. It was unknown how the biogas production and the process stability are influenced by certain parameter shifts in glycolate feed, pH of the feed, oxygen input and temperature. Therefore, different parameter changes were applied to the reactor...

  4. Local and regional influences over soil microbial metacommunities in the Transantarctic Mountains

    OpenAIRE

    Sokol, E. R.; Herbold, C.W.; C.K. LEE; Cary, S. C.; Barrett, J E

    2013-01-01

    The metacommunity concept provides a useful framework to assess the influence of local and regional controls over diversity patterns. Culture-independent studies of soil microbial communities in the McMurdo Dry Valleys of East Antarctica (77 degrees S) have shown that bacterial diversity is related to soil geochemical gradients, while studies targeting edaphic cyanobacteria have linked local diversity patterns to dispersal-based processes. In this study, we increased the spatial extent of obs...

  5. Influence of free air space on microbial kinetics in passively aerated compost.

    Science.gov (United States)

    Yu, Shouhai; Clark, O Grant; Leonard, Jerry J

    2009-01-01

    The influence of free air space (FAS) on passively aerated composting has been reported, but the quantitative relationship between FAS and the microbial kinetics in passively aerated compost has not been investigated. This relationship was studied by composting dairy manure and straw in an enclosed, passively aerated, cylindrical vessel. Based on this experimental system, conceptual and numerical models were developed in which the compost bed was considered to consist of layered elements, each being physically and chemically homogeneous. The microbial activity in each layer was represented in order to predict oxygen and substrate consumption and the release of water and heat. Convective transport of air, moisture, and heat through the layers was represented. Microbial growth and substrate consumption rates were described using modified first-order kinetics for each of the mesophilic and thermophilic temperature regimes. The values of the microbial kinetic parameters were adjusted for each layer based on an innovative, non-linear, statistical analysis of temperature histories recorded at different layers in the compost bed during three treatments (i.e., FAS values of 0.45, 0.52, and 0.65). Microbial kinetic rate constants were found to follow a sigmoid relationship with FAS, with correlation coefficients (R(2)) of 0.97 for the mesophilic stage and 0.96 for the thermophilic stage. Temperature histories and airflow measurements from a fourth treatment (FAS value of 0.57) were used as an independent check of the model's performance. Simulation results indicate that the model could predict the general trend of temperature development. A plot of the residuals shows that the model is biased, however, possibly because many parameters in the model were not measured directly but instead were estimated from literature. The result from this study demonstrates a new method for describing the relationship between microbial kinetics (k(max)) and substrate FAS, which could be used

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

    Science.gov (United States)

    Feng, Cuijie; Li, Jiangwei; Qin, Dan; Chen, Lixiang; Zhao, Feng; Chen, Shaohua; Hu, Hongbo; Yu, Chang-Ping

    2014-01-01

    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.

  7. 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.

  8. 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...

  9. Citrate influences microbial Fe hydroxide reduction via a dissolution-disaggregation mechanism

    Science.gov (United States)

    Braunschweig, Juliane; Klier, Christine; Schröder, Christian; Händel, Matthias; Bosch, Julian; Totsche, Kai U.; Meckenstock, Rainer U.

    2014-08-01

    Microbial reduction of ferric iron is partly dependent on Fe hydroxide particle size: nanosized Fe hydroxides greatly exceed the bioavailability of their counterparts larger than 1 μm. Citrate as a low molecular weight organic acid can likewise stabilize colloidal suspensions against aggregation by electrostatic repulsion but also increase Fe bioavailability by enhancing Fe hydroxide solubility. The aim of this study was to see whether adsorption of citrate onto surfaces of large ferrihydrite aggregates results in the formation of a stable colloidal suspension by electrostatic repulsion and how this effect influences microbial Fe reduction. Furthermore, we wanted to discriminate between citrate-mediated colloid stabilization out of larger aggregates and ferrihydrite dissolution and their influence on microbial Fe hydroxide reduction. Dissolution kinetics of ferrihydrite aggregates induced by different concentrations of citrate and humic acids were compared to microbial reduction kinetics with Geobacter sulfurreducens. Dynamic light scattering results showed the formation of a stable colloidal suspension and colloids with hydrodynamic diameters of 69 (±37) to 165 (± 65) nm for molar citrate:Fe ratios of 0.1 to 0.5 and partial dissolution of ferrihydrite at citrate:Fe ratios ⩾ 0.1. No dissolution or colloid stabilization was detected in the presence of humic acids. Adsorption of citrate, necessary for dissolution, reversed the surface charge and led to electrostatic repulsion between sub-aggregates of ferrihydrite and colloid stabilization when the citrate:Fe ratio was above a critical value (⩽ 0.1). Lower ratios resulted in stronger ferrihydrite aggregation instead of formation of a stable colloidal suspension, owing to neutralization of the positive surface charge. At the same time, microbial ferrihydrite reduction increased from 0.029 to 0.184 mM h-1 indicating that colloids stabilized by citrate addition enhanced microbial Fe reduction. Modelling of

  10. 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.

  11. 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.

  12. [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.

  13. 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.

  14. Pathogenic bacteria and microbial-source tracking markers in Brandywine Creek Basin, Pennsylvania and Delaware, 2009-10

    Science.gov (United States)

    Duris, Joseph W.; Reif, Andrew G.; Olson, Leif E.; Johnson, Heather E.

    2011-01-01

    The City of Wilmington, Delaware, is in the downstream part of the Brandywine Creek Basin, on the main stem of Brandywine Creek. Wilmington uses this stream, which drains a mixed-land-use area upstream, for its main drinking-water supply. Because the stream is used for drinking water, Wilmington is in need of information about the occurrence and distribution of specific fecally derived pathogenic bacteria (disease-causing bacteria) and their relations to commonly measured fecal-indicator bacteria (FIB), as well as information regarding the potential sources of the fecal pollution and pathogens in the basin. This study focused on five routinely sampled sites within the basin, one each on the West Branch and the East Branch of Brandywine Creek and at three on the main stem below the confluence of the West and East Branches. These sites were sampled monthly for 1 year. Targeted event samples were collected on two occasions during high flow and two occasions during normal flow. On the basis of this study, high flows in the Brandywine Creek Basin were related to increases in FIB densities, and in the frequency of selected pathogen and source markers, in the West Branch and main stem of Brandywine Creek, but not in the East Branch. Water exceeding the moderate fullbody-contact single-sample recreational water-quality criteria (RWQC) for Escherichia coli (E. coli) was more likely to contain selected markers for pathogenic E. coli (eaeA,stx1, and rfbO157 gene markers) and bovine fecal sources (E. hirae and LTIIa gene markers), whereas samples exceeding the enterococci RWQC were more likely to contain the same pathogenic markers but also were more likely to carry a marker indicative of human source (esp gene marker). On four sample dates, during high flow between October and March, the West Branch was the only observed potential contributor of selected pathogen and bovine source markers to the main stem of Brandywine Creek. Indeed, the stx2 marker, which indicates a highly

  15. 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

  16. 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

    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.

  17. 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.

  18. 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.

  19. 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;

  20. 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

  1. Influence of Legionella pneumophila and other water bacteria on the survival and growth of Acanthamoeba polyphaga.

    Science.gov (United States)

    Anacarso, I; Guerrieri, E; Bondi, M; de Niederhäusern, S; Iseppi, R; Sabia, C; Contri, M; Borella, P; Messi, P

    2010-10-01

    We investigated in solid medium, in water microcosm co-cultures and by light and transmission electron microscopy the influence of Legionella pneumophila Lp-1, Pseudomonas aeruginosa ATCC 27853, Burkholderia cepacia ATCC 25416 and Pseudomonas fluorescens SSD35 on the growth and survival of Acanthamoeba polyphaga. The infection with L. pneumophila was microscopically characterized by the presence of few bacteria inside protozoa at 4th h, and by the beginning of disruptive effects in late phase of trial. In water microcosm studies, performed at different temperature, the more significant interactions were observed at 30°C. In these conditions, L. pneumophila caused a marked reduction in trophozoite and cyst counts from the 4th day until the end of incubation (11 days). B. cepacia showed, by microscopic observation, few and generally single rods within protozoan phagosomes and caused a light reduction of trophozoite viability and cyst formation in co-cultures. A more invasive type of endocytosis, characterized by an early invasion with the presence of a high bacteria number inside amoebae, was observed for Pseudomonas strains. P. fluorescens produced a violent lysis of the host, whereas P. aeruginosa did not cause lysis or suffering. These results underline that water bacteria other than legionella are capable of intracellular survival in Acanthamoeba, influencing the protozoa viable cycle.

  2. Organic content influences sediment microbial fuel cell performance and community structure.

    Science.gov (United States)

    Zhao, Qing; Li, Ruying; Ji, Min; Ren, Zhiyong Jason

    2016-11-01

    This study constructed sediment microbial fuel cells (SMFCs) with different organic loadings without the amendment of external substrates, and it investigated how such variation affects electricity generation and microbial community structure. Results found sediment characteristics significantly influenced SMFC performance and appropriate organic content is important to maintain stable power outputs. SMFCs with loss of ignition (LOI) of 5% showed the most reliable performance in this study, while high organic content (LOI 10-16%) led to higher but very unstable voltage output because of biogas accumulation and worm activities. SMFCs with low organic content (1-3%) showed low power output. Different bacterial communities were found in SMFCs shown various power generation performance even those with similar organic contents. Thermodesulfovibrionaceae was found closely related to the system startup and Desulfobulbaceae showed great abundance in SMFCs with high power production.

  3. 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.

  4. Biochar influences the microbial community structure during tomato stalk composting with chicken manure.

    Science.gov (United States)

    Wei, Liu; Shutao, Wang; Jin, Zhang; Tong, Xu

    2014-02-01

    A batch composting study was performed to evaluate effects of biochar addition on dynamics of microbial community and changes of key physic-chemical properties during composting of tomato stalk and chicken manure. As a comparison, two amendments of peat bog and zeolite were selected. The results indicated that biochar addition for composting showed a shorter time to enter thermophilic phase (3 d) and a higher temperature (56°C) and longer duration of thermophilic phase compared to that of peat bog addition, zeolite addition and raw composts. The highest C/N ratio and volatile fatty acids' concentration with biochar addition were obtained. Biochar addition also showed more influence on bacterial community changes than that of peat bog and zeolite. Thus, biochar addition could significantly affect physic-chemical process and microbial community diversity on tomato stalk and chicken manure composting. This study provides valuable information for improving composting and a better understanding of biodegradation processes.

  5. Self-sustaining, solar-driven bioelectricity generation in micro-sized microbial fuel cell using co-culture of heterotrophic and photosynthetic bacteria

    Science.gov (United States)

    Liu, Lin; Choi, Seokheun

    2017-04-01

    Among many energy harvesting techniques with great potential, microbial fuel cell (MFC) technology is arguably the most underdeveloped. Even so, excitement is building, as microorganisms can harvest electrical power from any biodegradable organic source (e.g. wastewater) that is readily available in resource-limited settings. Nevertheless, the requirement for endless introduction of organic matter imposes a limiting factor to this technology, demanding an active feeding system and additional power. Here, we demonstrated self-sustaining bioelectricity generation from a microliter-scale microbial fuel cell (MFC) by using the syntrophic interaction between heterotrophic exoelectrogenic bacteria and phototrophs. The MFC continuously generated light-responsive electricity from the heterotrophic bacterial metabolic respiration with the organic substrates produced by photosynthetic bacteria. Without additional organic fuel, the mixed culture in a 90-μL-chamber MFC generated self-sustained current for more than 13 days, while the heterotrophic culture produced current that decreased dramatically within a few hours. The current from the mixed culture was about 70 times greater than that of the device with only photosynthetic bacteria. The miniaturization provided a short start-up time, a well-controlled environment, and small internal resistance. Those advantages will become the general design platform for micropower generation.

  6. Influence of microbial composition on foam formation in a manure-based digester

    DEFF Research Database (Denmark)

    Kougias, Panagiotis; Boe, Kanokwan; O-Thong, Sompong

    2012-01-01

    Foaming is one of the major problems that occasionally occur in the biogas plants, affecting negatively the overall digestion process and results in adverse operational, economical and environmental impacts. The most dominant factors contributing to foaming are organic overloading, feedstock...... composition and the presence of specific microorganisms. The filamentous microorganisms are known to be the major cause of foaming in sludge digester as they are attached to the gas bubbles and accumulated on the surface of the reactor. The present case study investigated the microbial composition of one...... manure-based digester of Lemvig biogas plant that was facing foaming problem, comparing with three non-foaming digesters. The research was focused on the quantitative and qualitative analysis of Bacteria and Archaea population and on the identification of Gordonia sp. The reactor samples were analysed...

  7. 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.

  8. The influence of bacterial inoculants on the microbial ecology of aerobic spoilage of barley silage.

    Science.gov (United States)

    Inglis, G D; Yanke, L J; Kawchuk, L M; McAllister, T A

    1999-01-01

    The aerobic decomposition of barley silage treated with two inoculants (LacA and LacB) containing mixtures of Lactobacillus plantarum and Enterococcus faecium was investigated over a 28-day period. Initially, yeast and bacterial populations were larger in silage inoculated with LacA than in silage treated with LacB or water alone (control). Differences in the succession of yeasts in silage treated with LacA were observed relative to the other two treatments. From silage treatment with LacA, Issatchenkia orientalis was the most prevalent yeast taxon over all of the sample times, and the filamentous fungus Microascus brevicaulis was also frequently isolated at later sample dates (> or = 14 days). In contrast, Saccharomyces exiguus was the most prominent yeast recovered from silage treated with LacB and water alone on days 2 and 4, although it was supplanted by I. orientalis at later sample times. Successional trends of bacteria were similar for all three treatments. Lactobacillus spp. were initially the most prevalent bacteria isolated, followed by Bacillus spp. (primarily Bacillus pumilus). However, the onset of Bacillus spp. prominence was faster in LacA silage, and Klebsiella planticola was frequently recovered at later sample times (> or = 14 days). More filamentous fungi were recovered from LacA silage on media containing carboxylmethylcellulose, pectin, or xylan. The most commonly isolated taxa were Absidia sp., Aspergillus flavus, Aspergillus fumigatus, Byssochlamys nivea, Monascus ruber, Penicillium brevicompactum, Pseudoallescheria boydii, and M. brevicaulis. The results of this study indicated that the two bacterial inoculants incorporated into barley at the time of ensilage affected the microbial ecology of silage decomposition following exposure to air. However, neither of the microbial inoculants effectively delayed aerobic spoilage of barley silage, and the rate of decomposition of silage treated with one of the inoculants (LacA) was actually enhanced.

  9. Evaluation on factors influencing the heterotrophic growth on the soluble microbial products of autotrophs.

    Science.gov (United States)

    Ni, Bing-Jie; Zeng, Raymond J; Fang, Fang; Xie, Wen-Ming; Xu, Juan; Sheng, Guo-Ping; Sun, Yu-Jiao; Yu, Han-Qing

    2011-04-01

    In this work, the heterotrophic growth on the microbial products of autotrophs and the effecting factors were evaluated with both experimental and modeling approaches. Fluorescence in situ hybridization (FISH) analysis illustrated that ammonia oxidizers (AOB), nitrite oxidizers (NOB), and heterotrophs accounted for about 65%, 20%, and 15% of the total bacteria, respectively. The mathematical evaluation of experimental data reported in literature indicated that heterotrophic growth in nitrifying biofilm (30-50%) and granules (30%) was significantly higher than that of nitrifying sludge (15%). It was found that low influent ammonium resulted in a lower availability of soluble microbial products (SMP) and a slower heterotrophic growth, but high ammonium (>150 mg N L(-1)) feeding would lead to purely AOB dominated sludge with high biomass-associated products contained effluent, although the absolute heterotrophic growth increased. Meanwhile, the total active biomass concentration increased gradually with the increasing solids retention time, whereas the factions of active AOB, NOB, and heterotrophs varied a lot at different solids retention times. This work could be useful for better understanding of the autotrophic wastewater treatment systems.

  10. Total Phosphate Influences the Rate of Hydrocarbon Degradation but Phosphate Mineralogy Shapes Microbial Community Composition in Cold-Region Calcareous Soils.

    Science.gov (United States)

    Siciliano, Steven D; Chen, Tingting; Phillips, Courtney; Hamilton, Jordan; Hilger, David; Chartrand, Blaine; Grosskleg, Jay; Bradshaw, Kris; Carlson, Trevor; Peak, Derek

    2016-05-17

    Managing phosphorus bioaccessibility is critical for the bioremediation of hydrocarbons in calcareous soils. This paper explores how soil mineralogy interacts with a novel biostimulatory solution to both control phosphorus bioavailability and influence bioremediation. Two large bore infiltrators (1 m diameter) were installed at a PHC contaminated site and continuously supplied with a solution containing nutrients and an electron acceptor. Soils from eight contaminated sites were prepared and pretreated, analyzed pretrial, spiked with diesel, placed into nylon bags into the infiltrators, and removed after 3 months. From XAS, we learned that three principal phosphate phases had formed: adsorbed phosphate, brushite, and newberyite. All measures of biodegradation in the samples (in situ degradation estimates, mineralization assays, culturable bacteria, catabolic genes) varied depending upon the soil's phosphate speciation. Notably, adsorbed phosphate increased anaerobic phenanthrene degradation and bzdN catabolic gene prevalence. The dominant mineralogical constraints on community composition were the relative amounts of adsorbed phosphate, brushite, and newberyite. Overall, this study finds that total phosphate influences microbial community phenotypes whereas relative percentages of phosphate minerals influences microbial community genotype composition.

  11. Influence of anode potentials on selection of Geobacter strains in microbial electrolysis cells.

    Science.gov (United States)

    Commault, Audrey S; Lear, Gavin; Packer, Michael A; Weld, Richard J

    2013-07-01

    Through their ability to directly transfer electrons to electrodes, Geobacter sp. are key organisms for microbial fuel cell technology. This study presents a simple method to reproducibly select Geobacter-dominated anode biofilms from a mixed inoculum of bacteria using graphite electrodes initially poised at -0.25, -0.36 and -0.42 V vs. Ag/AgCl. The biofilms all produced maximum power density of approximately 270 m Wm(-2) (projected anode surface area). Analysis of 16S rRNA genes and intergenic spacer (ITS) sequences found that the biofilm communities were all dominated by bacteria closely related to Geobacter psychrophilus. Anodes initially poised at -0.25 V reproducibly selected biofilms that were dominated by a strain of G. psychrophilus that was genetically distinct from the strain that dominated the -0.36 and -0.42 V biofilms. This work demonstrates for the first time that closely related strains of Geobacter can have very different competitive advantages at different anode potentials.

  12. 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.

  13. 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

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

    Directory of Open Access Journals (Sweden)

    JD Medeiros

    Full Text Available 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.

  15. Influence of sulfate on the transport of bacteria in quartz sand.

    Science.gov (United States)

    Shen, Xiufang; Han, Peng; Yang, Haiyan; Kim, Hyunjung; Tong, Meiping

    2013-10-01

    The influence of sulfate on the transport of bacteria in packed quartz sand was examined at a constant 25mM ionic strength with the sulfate concentration progressively increased from 0 to 20mM at pH 6.0. Two representative cell types, Escherichia coli BL21 (Gram-negative) and Bacillus subtilis (Gram-positive), were used to determine the effect of sulfate on cell transport behavior. For both examined cell types, the breakthrough plateaus in the presence of sulfate in suspensions were higher and the corresponding retained profiles were lower than those without sulfate ions, indicating that the presence of sulfate in suspensions increased cell transport in packed quartz sand regardless of the examined cell types (Gram-positive or Gram-negative). Moreover, the enhancement of bacteria transport induced by the presence of sulfate was more pronounced with increasing sulfate concentration from 5 to 20mM. In contrast with the results for EPS-present bacteria, the presence of sulfate in solutions did not change the transport behavior for EPS-removed cells. The zeta potentials of EPS-present cells with sulfate were found to be more negative relative to those without sulfate in suspensions, whereas, the zeta potentials for EPS-removed cells in the presence of sulfate were similar as those without sulfate. We proposed that sulfate could interact with EPS on cell surfaces and thus negatively increased the zeta potentials of bacteria, contributing to the increased transport in the presence of sulfate in suspensions.

  16. Extensive microbial mats and their influences on the erosional and depositional dynamics of a siliciclastic cold water environment (Lower Arenigian, Montagne Noire, France)

    Science.gov (United States)

    Noffke, N.

    2000-11-01

    Lower Arenigian (Ordovician) rocks of the Montagne Noire, France, represent a shallow-marine environment of a high latitude position along the northern margin of Gondwana. Within the weakly metamorphosed siliciclastics six depositional units were recognized: (1) outer shelf; (2) foreshore zone, below wave base; (3) foreshore zone, above wave base; (4) sand bars of shoreface zone; (5) intertidal deposits; and (6) lagoonal zone. Wrinkle structures and various other phenomena were mediated by coherent (cyano-)bacterial mats. The structures can be related to the different facies zones of the paleoenvironment. Whereas the muddy outer shelf, and the high-energetic sand bars were not overgrown by any mat-constructing microbial populations, fine sands of the foreshore zone, the tidal flats and lagoonal areas were widely colonized. Restriction of mats due to competition of space by endobenthic macroorganisms, or by grazers was low. The microbially induced structures are composed of organic material, pyrite, clay minerals (illite, chamsonite, chlorite), and chert. The minerals precipitated in situ during degradation of the organic layers by the activity of heterotrophic bacteria at low temperatures. Because the microorganisms formed a dense organic carpet covering extensive areas of the ancient sea-bottom, they influenced significantly the erosional and depositional dynamics of the sedimentary system of the local Arenigian. Biostabilization counteracted erosion, and baffling, trapping and binding enriched mineral particles. Additionally, the in situ formed minerals contributed to the total amount of sediment. The biotic influence lead to increased accumulation of sediment within the depositional area. The study shows that microbial mats of great extension occur within Phanerozoic siliciclastics of cold paleoclimate zones, and that preservation of the mat fabrics was possible. The significant mats influenced the local sedimentary system, an aspect scarcely taken into account

  17. Influence of soil moisture on linear alkylbenzene sulfonate-induced toxicity in ammonia-oxidizing bacteria.

    Science.gov (United States)

    Nielsen, Klaus B; Brandt, Kristian K; Jacobsen, Anne-Marie; Mortensen, Gerda K; Sørensen, Jan

    2004-02-01

    Moisture affects bioavailability and fate of pollutants in soil, but very little is known about moisture-induced effects on pollutant toxicity. We here report on a modifying effect of moisture on degradation of linear alkylbenzene sulfonates (LASs) and on their toxicity towards ammonia-oxidizing bacteria (AOB) in agricultural soil. In soil spiked with two LAS levels (250 or 1,000 mg/kg) and incubated at four different moisture levels (9-100% of water-holding capacity), degradation was strongly affected by both soil moisture and initial LAS concentration, resulting in degradation half-lives ranging from 13 to more than 160 d. Toxicity towards AOB assessed by a novel Nitrosomonas europaea luxAB-reporter assay was correlated to total LAS concentration, indicating that LAS remained bioavailable over time without accumulation of toxic intermediates. Toxicity towards indigenous AOB increased with increasing soil moisture. The results indicate that dry soil conditions inhibit LAS degradation and provide protection against toxicity within the indigenous AOB, thus allowing for a rapid recovery of this population when LAS degradation is resumed and completed after rewetting. We propose that the protection of microbial populations against toxicity in dry soil may be a general phenomenon caused primarily by limited diffusion and thus a low bioavailability of the toxicant.

  18. Uptake of photosensitizers by bacteria is influenced by the presence of cations

    Science.gov (United States)

    Kishen, A.; George, S.

    2007-05-01

    This investigation studies the influence of cations on photosensitizer uptake by Enterococcus faecalis (gram positive) and Actinobacillus actinomycetemcomitans (gram negative). Methods- The uptake of Methylene blue (MB) and Indocyanine Green (ICG), by bacteria were studied under the influence of divalent cations (CaCl II & MgCl II) and EDTA. Further, E. faecalis cells subjected to trypsinisation and calcium channel blocker (verapamil) were also analysed for MB and ICG uptake inorder to understand the mechanism of photosensitizer uptake. Results- Uptake of ICG was enhanced in the presence of divalent cations in E. faecalis and A. actinomycetemcomitans. Treating cells with EDTA had no significant effect on the photosensitizer uptake, although the highest concentration tested showed an enhancement of uptake. In contrast to ICG, MB showed a decreased uptake by bacterial cells on subjecting them to divalent cations and EDTA. Calcium channel blocker had no significant inhibitory effect on photosensitizers uptake. However, trypsin treatment resulted in significant reduction of ICG uptake. The result suggested that ICG uptake by bacteria is mediated through specific transporter protein while MB is associated with the outer surface structures of bacterial cells.

  19. The Influence of Soft Layer Electrokinetics on Electroporation of Gram-positive Bacteria

    Science.gov (United States)

    Dingari, Naga Neehar; Moran, Jeffrey L.; Garcia, Paulo A.; Buie, Cullen R.

    2016-11-01

    Bacterial electroporation involves subjecting cells to intense ( 10 kV/cm) electric pulses, to open pores on the cell membrane for intracellular delivery of exogenous molecules. Its high efficiency in genetic transformation makes it an attractive tool for synthetic biology. While mammalian cell electroporation has received extensive theoretical and experimental investigation, bacterial electroporation has received markedly less attention. In this work, we develop a theoretical model of electroporation for gram-positive bacteria, taking into account the effect of the bacterial cell envelope on the cell's response to an electroporation pulse. We model the influence of the cell wall charge on the electrokinetic transport (and hence the pore properties) around the bacterial cell envelope using the Poisson-Nernst-Planck equations. Further, we account for the influence of the cell wall's mechanical elasticity on the pore radius evolution during electroporation, which is typically neglected in mammalian cell electroporation. This yields valuable information about favorable conditions for pore formation and will enable designing optimal platforms for bacteria electroporation.

  20. 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.

  1. Synbiotic preparation with Lactic acid bacteria and inulin as a functional food: In vivo evaluation of microbial activities, and preneoplastic aberrant crypt foci

    Directory of Open Access Journals (Sweden)

    Chaiyavat CHAIYASUT

    Full Text Available Abstract Host microbiome and metabolome are associated with the incidence of colorectal cancer (CC, one of the major health problems in developed countries. The pro and prebiotic supplementation helps to improve the host health. Inulin is one such prebiotic used for the enhancement of naïve probiotic bacterial population. This paper explains the impact of inulin (PRE extracted from Jerusalem artichoke (JA, Lactobacillus plantarum HII11 (PRO, and synbiotic (SYN; inulin + L. plantarum HII11 preparation on Azoxymethane mediated CC induced rat model with respect to changes in microbial load, microbial enzymes, and preneoplastic aberrant crypt foci. The results suggested that the PRE and SYN supplementation effectively reduced the selected pathogenic bacteria (Salmonella spp., and Escherichia coli, microbial enzymes and increased the probiotic load. The intervention of SYN significantly reduced the colonic ACF in CC model. The study results revealed that the supplementation of SYN diet (inulin and L. plantarum HII11 protects the AOM-mediated colon cancer induced host.

  2. 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

  3. Environmental heterogeneity and microbial inheritance influence sponge-associated bacterial composition of Spongia lamella.

    Science.gov (United States)

    Noyer, Charlotte; Casamayor, Emilio O; Becerro, Mikel A

    2014-10-01

    Sponges are important components of marine benthic communities. High microbial abundance sponges host a large diversity of associated microbial assemblages. However, the dynamics of such assemblages are still poorly known. In this study, we investigated whether bacterial assemblages present in Spongia lamella remained constant or changed as a function of the environment and life cycle. Sponges were collected in multiple locations and at different times of the year in the western Mediterranean Sea and in nearby Atlantic Ocean to cover heterogeneous environmental variability. Co-occurring adult sponges and offsprings were compared at two of the sites. To explore the composition and abundance of the main bacteria present in the sponge mesohyl, embryos, and larvae, we applied both 16S rRNA gene-denaturing gradient gel electrophoresis (DGGE) and sequencing of excised DGGE bands and quantitative polymerase chain reactions (qPCR). On average, the overall core bacterial assemblage showed over 60 % similarity. The associated bacterial assemblage fingerprints varied both within and between sponge populations, and the abundance of specific bacterial taxa assessed by qPCR significantly differed among sponge populations and between adult sponge and offsprings (higher proportions of Actinobacteria in the latter). Sequences showed between 92 and 100 % identity to sequences previously reported in GenBank, and all were affiliated with uncultured invertebrate bacterial symbionts (mainly sponges). Sequences were mainly related to Chloroflexi and Acidobacteria and a few to Actinobacteria and Bacteroidetes. Additional populations may have been present under detection limits. Overall, these results support that both ecological and biological sponge features may shape the composition of endobiont bacterial communities in S. lamella.

  4. [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.

  5. 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

    g/L in the volume of 350 g/L. To revitalize bacteria and activate gas production, 200 mL salty water and 5 mL molasses were added. On the 6th day of the experiment, the maximum production was 1300 mL at 90 g/L and the minimum of 400 mL at 80 g/L. The experiment showed that bacteria of anaerobic...

  6. Coexistence facilitates interspecific biofilm formation in complex microbial communities

    DEFF Research Database (Denmark)

    Madsen, Jonas Stenløkke; Røder, Henriette Lyng; Russel, Jakob

    2016-01-01

    Social interactions in which bacteria respond to one another by modifying their phenotype are central determinants of microbial communities. It is known that interspecific interactions influence the biofilm phenotype of bacteria; a phenotype that is central to the fitness of bacteria. However...... correlated with an increase in planktonic cell numbers, thus implying a behavioral response rather than mere growth competition. Our findings suggest that an increase in biofilm formation is a common adaptive response to long-term coexistence....

  7. 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.

  8. 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.

  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.

  10. Syntrophic interactions between H2-scavenging and anode-respiring bacteria can improve current density in microbial electrochemical cells

    Science.gov (United States)

    High current density of 10.0-14.6 A/m2 and COD removal up to 96% were obtained in a microbial electrochemical cell (MEC) fed with digestate at hydraulic retention time (HRT) of 4d and 8d. Volatile fatty acids became undetectable in MEC effluent (HRT 8d), except for trivial acetat...

  11. 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

  12. Can Transgenic Maize Affect Soil Microbial Communities?

    NARCIS (Netherlands)

    Mulder, Christian; Wouterse, Marja; Raubuch, Markus; Roelofs, Willem; Rutgers, Michiel

    2006-01-01

    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 gu

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

    Directory of Open Access Journals (Sweden)

    Pirvu Lucia

    2016-01-01

    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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. Methane Emissions and Microbial Communities as Influenced by Dual Cropping of Azolla along with Early Rice

    Science.gov (United States)

    Liu, Jingna; Xu, Heshui; Jiang, Ying; Zhang, Kai; Hu, Yuegao; Zeng, Zhaohai

    2017-01-01

    Azolla caroliniana Willd. is widely used as a green manure accompanying rice, but its ecological importance remains unclear, except for its ability to fix nitrogen in association with cyanobacteria. To investigate the impacts of Azolla cultivation on methane emissions and environmental variables in paddy fields, we performed this study on the plain of Dongting Lake, China, in 2014. The results showed that the dual cropping of Azolla significantly suppressed the methane emissions from paddies, likely due to the increase in redox potential in the root region and dissolved oxygen concentration at the soil-water interface. Furthermore, the floodwater pH decreased in association with Azolla cultivation, which is also a factor significantly correlated with the decrease in methane emissions. An increase in methanotrophic bacteria population (pmoA gene copies) and a reduction in methanogenic archaea (16S rRNA gene copies) were observed in association with Azolla growth. During rice cultivation period, dual cropping of Azolla also intensified increasing trend of 1/Simpson of methanogens and significantly decreased species richness (Chao 1) and species diversity (1/Simpson, 1/D) of methanotrophs. These results clearly demonstrate the suppression of CH4 emissions by culturing Azolla and show the environmental and microbial responses in paddy soil under Azolla cultivation.

  19. 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

  20. 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.

  1. 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...... (measured as heterotrophic plate counts, HPC) were investigated in microcosms at 7 °C, containing non-sterilised drinking water, drinking water sediment and A. aquaticus collected from a non-chlorinated ground water based drinking water supply system. Concentrations of E. coli, K. pneumoniae and C. jejuni...... 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...

  2. Influence of applied voltage on the performance of bioelectrochemical anaerobic digestion of sewage sludge and planktonic microbial communities at ambient temperature.

    Science.gov (United States)

    Feng, Qing; Song, Young-Chae; Bae, Byung-Uk

    2016-11-01

    The influence of applied voltage on the bioelectrochemical anaerobic digestion of sewage sludge was studied at ambient temperature (25±2°C). The stability of the bioelectrochemical anaerobic digestion was considerably good in terms of pH, alkalinity and VFAs at 0.3V and 0.5V, but VFA accumulation occurred at 0.7V. The specific methane production rate (370mLCH4/L.d) was the highest at 0.3V, but the methane content (80.6%) in biogas and the methane yield (350mLCH4/gCODr) were higher at 0.5V, significantly better than those of 0.7V. The VS removal efficiency was 64-66% at 0.3V and 0.5V, but only 31% at 0.7V. The dominant species of planktonic microbial communities was Cloacamonas at 0.3V and 0.5V, but the percentage of hydrolytic bacteria species such as Saprospiraceae, Fimbriimonas, and Ottowia pentelensis was much higher at 0.7V. The optimal applied voltage for bioelectrochemical anaerobic digestion was 0.3-0.5V according to digestion performance and planktonic microbial communities.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Influence of the root system of the Common Osier (Salix viminalis L.) on abundance of heterotrophic bacteria in the willow sewage treatment system.

    Science.gov (United States)

    Lalke-Porczyk, Elzbieta; Brzezinska, Maria Swiontek; Donderski, Wojciech

    2009-06-01

    The impact of the Common Osier (Salix viminalis L.) root system on number (CFU) of heterotrophic bacteria and their production in a soil-willow filter was examined. The Osier rhizosphere was found to be suitable habitat for growth of the examined microbial group, and the root system stimulated development of heterotrophic bacteria. The rhizosphere bacteria to control soil bacteria (R:C) ratio oscillated between 2.48 and 2.75 depending on the location of sample collection. The highest abundance of bacteria as well as highest bacterial production was observed at location I, near sewage discharge onto the plot. There was a significant positive correlation between the number of heterotrophic bacteria and the bacterial production.

  8. 复合微生物肥料功能菌的筛选与培养%Screening and Culturing of Bacteria for Compound Microbial Fertilizer

    Institute of Scientific and Technical Information of China (English)

    李朔; 严如玉; 张鹏; 易欣欣

    2012-01-01

    [目的]筛选出分别可固氮、解磷、解钾的菌株,对其进行鉴定,并利用它们生产微生物肥料。[方法]从供试土壤中分离出目的菌,测定其代谢能力,分别进行16S rDNA测序菌种鉴定,并进行液体培养正交试验,以及尝试固体培养生存复合微生物有机肥。[结果]分离得到代谢能力较强的固氮、解磷、解钾菌N2、P1、K5;鉴定分别为Klebsiella oxytoca、Bacillus cereus和Bacillus mucilaginous;培养条件对有效活菌数的影响大小程度为温度〉C/N〉pH〉转速,最佳培养条件温度32℃,C/N比30,pH 7.0,转速140 r/min,在最佳条件下48 h达到1.78×1010CFU/mL;尝试利用该复合微生物进行固体发酵生产复合微生物有机肥,96h得到有效活菌数2.23×109CFU/g。[结论]筛选出了固氮、解磷及解钾菌株,并对其培养条件进行了优化,为进行生物有机肥生产奠定了基础。%[Objective]The research aims to screen and identify the strains which have the ability of fixing nitrogen,dissolving phosphorus and releasing potassium,and use these bacteria to produce the microbial fertilizer.[Method]The bacteria were separated from soil,then their related metabolism ability was determined,and their specific 16s rDNA was sequenced.Meanwhile,liquid culture of orthogonal test was carried out and solid culture was used to culture compound microbial fertilizer.[Result] The purpose bacteria N2,P1,K5 with strong metabolism ability were identified to be Klebsiella oxytoca,Bacillus cereus and B.mucilaginous.The effects of culture conditions on effective active bacteria number successively were temperatureC/NpHspeed.The best culture conditions were as follows: temperature 32 ℃,C/N=30,pH=7.0,speed 140 rpm(up to 1.78×1010 CFU/mL after 48 hours under the best condition).The compound microorganism was carried out solid culture to produce compound microbial fertilizer,and the effective active bacteria number was up to 2.23×109 CFU /g after 96 h

  9. Nitrate removal and bioenergy production in constructed wetland coupled with microbial fuel cell: Establishment of electrochemically active bacteria community on anode.

    Science.gov (United States)

    Wang, Junfeng; Song, Xinshan; Wang, Yuhui; Abayneh, Befkadu; Li, Yihao; Yan, Denghua; Bai, Junhong

    2016-12-01

    The constructed wetland coupled with microbial fuel cell (CW-MFC) systems operated at different substrate concentration and pH influents were evaluated for bioelectricity generation, contaminant removal and microbial community structure. Performance of CW-MFC was evaluated at organic loading rate of 75.3gCODm(-3)d(-1) and pH gradients of (5.18±0.14, 7.31±0.13, and 8.75±0.12) using carbon fiber felt as electrodes. Peak power density was observed at slightly neutral influent condition. Compared with the open circuit CW-MFC, average COD and NO3-N removal efficiency in CW-MFC increased by 8.3% and 40.2% respectively under slightly neutral pH of influents. However, the removal efficiency and bioenergy production have been inhibited with acidic influents. The relative abundance of beta-Proteobacteria, nitrobacteria and denitrifying bacteria was significantly promoted in closed-circuit CW-MFC. Using of CW-MFC as a biochemical method for nitrate removal and bioelectricity generation under slightly neutral and alkaline influent conditions was a promising technology.

  10. Diversity of cultivable bacteria involved in the formation of macroscopic microbial colonies (Cave silver on the walls of a cave in Slovenia

    Directory of Open Access Journals (Sweden)

    Blagajana Herzog Velikonja

    2014-01-01

    Full Text Available Karstic caves often support white, yellow, grey or pink microbial colonies that are termed ‘cave silver’ by speleologists. Using various sample pre-treatments and culture media, a wide variety of bacteria associated with these colonies were recovered from a cave in Slovenia, Pajsarjeva jama. Decreasing the inoculum size resulted in significant increases in viable counts, while pre-treatments had the opposite effect with the exception of microwave irradiation. While all growth media yielded viable counts, the maximal counts were observed on a low-nutrient TWA medium. Based on the 16S rRNA gene sequence of OTU representatives, the majority of the 80 isolates examined belonged to Streptomyces (25%, Micrococcus (16% and Rhodococcus (10% Other abundant groups were Pseudomonas (9%, Agrobacterium (8%, Lysobacter (6% and Paenibacillus (5%, while members of genera Microbacterium, Agrococcus, Arthrobacter, Bacillus, Kocuria, Oerskovia, Sphingomonas, Aerococcus, and Bosea represented a minor portion of cultivable diversity encountered. Members of Streptomyces and Agrobacterium were common to all samples. Although these microorganisms readily form colonies under laboratory conditions, they were unrelated to abundant environmental phylotypes recovered from same samples in a previous study. However, the comparative 16S rRNA analysis showed that microorganisms highly related to the ones obtained in this study were cultivated from other subterranean environments indicating that they might represent true microbial cave dwellers.

  11. Microbial communities associated with stable fly (Diptera: Muscidae) larvae and their developmental substrates

    Science.gov (United States)

    Bacteria are essential for stable fly (Stomoxys calcitrans (L.)) larval survival and development, but little is known about the innate microbial communities of stable flies, and it is not known if their varied dietary substrates influence their gut microbial communities. This investigation utilized ...

  12. Influence of oxygen partial pressure and salinity on the community composition of ammonia-oxidizing bacteria in the Schelde estuary

    NARCIS (Netherlands)

    Bollmann, A.; Laanbroek, H.J.

    2002-01-01

    The influence of environmental factors on the community structure of ammoniaoxidizing bacteria (AOB) was investigated in the Schelde estuary. Simultaneously with the increase of oxygen and salinity, a shift of the dominant AOB was observed. Molecular analysis based on 16S rRNA genes showed that the

  13. Influence of oxygen partial pressure and salinity on the community composition of ammonia-oxidizing bacteria in the Schelde estuary

    NARCIS (Netherlands)

    Bollmann, A.; Laanbroek, H.J.

    2002-01-01

    The influence of environmental factors on the community structure of ammonia-oxidizing bacteria (AOB) was investigated in the Schelde estuary. Simultaneously with the increase of oxygen and salinity, a shift of the dominant AOB was observed. Molecular analysis based on 16S rRNA genes showed that the

  14. 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

  15. 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.

  16. Microbial Quality and Direct PCR Identification of Lactic Acid Bacteria and Nonpathogenic Staphylococci from Artisanal Low-Acid Sausages

    OpenAIRE

    Aymerich, T.; B. Martín; Garriga, M.; Hugas, M

    2005-01-01

    Detection of six species of lactic acid bacteria and six species of gram-positive catalase-positive cocci from low-acid fermented sausages (fuets and chorizos) was assessed by species-specific PCR. Without enrichment, Lactobacillus sakei and Lactobacillus curvatus were detected in 11.8% of the samples, and Lactobacillus plantarum and Staphylococcus xylosus were detected in 17.6%. Enriched samples allowed the detection of L. sakei and S. xylosus in all of the samples (100%) and of Enterococcus...

  17. Long-Term Impacts of Bacteria-Sediment Interactions in Watershed-Scale Microbial Fate and Transport Modeling.

    Science.gov (United States)

    Liao, Hehuan; Krometis, Leigh-Anne H; Kline, Karen; Hession, W C

    2015-09-01

    Elevated levels of fecal indicator bacteria (FIB) remain the leading cause of surface water-quality impairments in the United States. Under the Clean Water Act, basin-specific total maximum daily load (TMDL) restoration plans are responsible for bringing identified water impairments in compliance with applicable standards. Watershed-scale model predictions of FIB concentrations that facilitate the development of TMDLs are associated with considerable uncertainty. An increasingly cited criticism of existing modeling practice is the common strategy that assumes bacteria behave similarly to "free-phase" contaminants, although many field evidence indicates a nontrivial number of cells preferentially associate with particulates. Few attempts have been made to evaluate the impacts of sediment on the predictions of in-stream FIB concentrations at the watershed scale, with limited observational data available for model development, calibration, and validation. This study evaluates the impacts of bacteria-sediment interactions in a continuous, watershed-scale model widely used in TMDL development. In addition to observed FIB concentrations in the water column, streambed sediment-associated FIB concentrations were available for model calibration. While improved model performance was achieved compared with previous studies, model performance under a "sediment-attached" scenario was essentially equivalent to the simpler "free-phase" scenario. Watershed-specific characteristics (e.g., steep slope, high imperviousness) likely contributed to the dominance of wet-weather pollutant loading in the water column, which may have obscured sediment impacts. As adding a module accounting for bacteria-sediment interactions would increase the model complexity considerably, site evaluation preceding modeling efforts is needed to determine whether the additional model complexity and effort associated with partitioning phases of FIB is sufficiently offset by gains in predictive capacity.

  18. Simultaneous photocatalytic and microbial degradation of dye-containing wastewater by a novel g-C3N4-P25/photosynthetic bacteria composite

    Science.gov (United States)

    Zhang, Xinying; Wu, Yan; Xiao, Gao; Tang, Zhenping; Wang, Meiyin; Liu, Fuchang; Zhu, Xuefeng

    2017-01-01

    Azo dyes are very resistant to light-induced fading and biodegradation. Existing advanced oxidative pre-treatment methods based on the generation of non-selective radicals cannot efficiently remove these dyes from wastewater streams, and post-treatment oxidative dye removal is problematic because it may leave many byproducts with unknown toxicity profiles in the outgoing water, or cause expensive complete mineralization. These problems could potentially be overcome by combining photocatalysis and biodegradation. A novel visible-light-responsive hybrid dye removal agent featuring both photocatalysts (g-C3N4-P25) and photosynthetic bacteria encapsulated in calcium alginate beads was prepared by self-assembly. This system achieved a removal efficiency of 94% for the dye reactive brilliant red X-3b and also reduced the COD of synthetic wastewater samples by 84.7%, successfully decolorized synthetic dye-contaminated wastewater and reduced its COD, demonstrating the advantages of combining photocatalysis and biocatalysis for wastewater purification. The composite apparently degrades X-3b by initially converting the dye into aniline and phenol derivatives whose aryl moieties are then attacked by free radicals to form alkyl derivatives, preventing the accumulation of aromatic hydrocarbons that might suppress microbial activity. These alkyl intermediates are finally degraded by the photosynthetic bacteria. PMID:28273118

  19. 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.

  20. 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

  1. Influence of erythromycin A on the microbial populations in aquaculture sediment microcosms.

    Science.gov (United States)

    Kim, Yong-Hak; Cerniglia, Carl E

    2005-07-01

    Degradation of erythromycin A was studied using two sediment samples obtained from the salmon and trout hatchery sites at Hupp Springs (HS) and Goldendale (GD), Washington, United States. The former site had been treated for 3 years with erythromycin-medicated feed prior to the experiments, and the latter site had not been treated with any antibiotic for at least 6 years. The two sediment microcosms treated with either N-[methyl-14C]erythromycin A or [1,3,5,7,9,11,13-14C]erythromycin A showed S-curves for erythromycin A mineralization with a prolonged lag time of 120 days, except for GD microcosms treated with [1,3,5,7,9,11,13-14C]erythromycin A. We proposed a simplified logistic model to interpret the mineralization curves under the assumption of the low densities of initial populations metabolizing erythromycin A. The model was helpful for knowing the biological potential for erythromycin A degradation in sediments. Although erythromycin A added to the two sediment microcosms did not significantly alter the numbers of total viable aerobic bacteria or erythromycin-resistant bacteria, it affected the bacterial composition. The influence on the bacterial composition appeared to be greater in GD microcosms without pre-exposure to antibiotics. PCR-RFLP and DNA sequence analyses of the 16S ribosomal RNA gene and the erythromycin esterase (ere) gene revealed that ereA type 2 (ereA2) was present in potentially erythromycin-degrading Pseudomonas spp. strains GD100, GD200, HS100, HS200 and HS300, isolated from erythromycin-treated and non-treated GD and HS microcosms. Erythromycin A appeared to influence the development and proliferation of strain GD200, possibly via the lateral gene transfer of ereA2.

  2. Influence of erythromycin A on the microbial populations in aquaculture sediment microcosms

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong-Hak [Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079 (United States)]. E-mail: yhkim660628@hotmail.com; Cerniglia, Carl E. [Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079 (United States)]. E-mail: ccerniglia@nctr.fda.gov

    2005-07-01

    Degradation of erythromycin A was studied using two sediment samples obtained from the salmon and trout hatchery sites at Hupp Springs (HS) and Goldendale (GD), Washington, United States. The former site had been treated for 3 years with erythromycin-medicated feed prior to the experiments, and the latter site had not been treated with any antibiotic for at least 6 years. The two sediment microcosms treated with either N-[methyl-{sup 14}C]erythromycin A or [1,3,5,7,9,11,13-{sup 14}C]erythromycin A showed S-curves for erythromycin A mineralization with a prolonged lag time of 120 days, except for GD microcosms treated with [1,3,5,7,9,11,13-{sup 14}C]erythromycin A. We proposed a simplified logistic model to interpret the mineralization curves under the assumption of the low densities of initial populations metabolizing erythromycin A. The model was helpful for knowing the biological potential for erythromycin A degradation in sediments. Although erythromycin A added to the two sediment microcosms did not significantly alter the numbers of total viable aerobic bacteria or erythromycin-resistant bacteria, it affected the bacterial composition. The influence on the bacterial composition appeared to be greater in GD microcosms without pre-exposure to antibiotics. PCR-RFLP and DNA sequence analyses of the 16S ribosomal RNA gene and the erythromycin esterase (ere) gene revealed that ereA type 2 (ereA2) was present in potentially erythromycin-degrading Pseudomonas spp. strains GD100, GD200, HS100, HS200 and HS300, isolated from erythromycin-treated and non-treated GD and HS microcosms. Erythromycin A appeared to influence the development and proliferation of strain GD200, possibly via the lateral gene transfer of ereA2.

  3. The influence of mineral fertilizer combined with a nitrification inhibitor on microbial populations and activities in calcareous Uzbekistanian soil under cotton cultivation.

    Science.gov (United States)

    Egamberdiyeva, D; Mamiev, M; Poberejskaya, S K

    2001-10-30

    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--N200 P140 K60 (T1), N200 PO P140 K60 (T2), and N200 P140 PO K60 (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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.)

  8. 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.

  9. Influence of silicate on the transport of bacteria in quartz sand and iron mineral-coated sand.

    Science.gov (United States)

    Dong, Zhe; Yang, Haiyan; Wu, Dan; Ni, Jinren; Kim, Hyunjung; Tong, Meiping

    2014-11-01

    The influence of silicate on the transport and deposition of bacteria (Escherichia coli) in packed porous media were examined at a constant 20 mM ionic strength with different silicate concentrations (from 0 to 1 mM) at pH 7. Transport experiments were performed in two types of representative porous media, both bare quartz sand and iron mineral-coated quartz sand. In bare quartz sand, the breakthrough plateaus in the presence of silicate in suspensions were lower and the corresponding retained profiles were higher than those without silicate ions, indicating that the presence of silicate in suspensions decreased cell transport in bare quartz sand. Moreover, the decrease of bacteria transport in quartz sand induced by silicate was more pronounced with increasing silicate concentrations from 0 to 1 mM. However, when EPS was removed from cell surfaces, the presence of silicate in cell suspensions (with different concentrations) did not affect the transport behavior of bacteria in quartz sand. The interaction of silicate with EPS on cell surfaces negatively decreased the zeta potentials of bacteria, resulting in the decreased cell transport in bare quartz sand when silicate was copresent in bacteria suspensions. In contrast, the presence of silicate in suspensions increased cell transport in iron mineral-coated sand. Silicate ions competed with bacteria for the adsorption sites on mineral-coated sand, contributing to the increased cell transport in mineral-coated sand with silicate present in cell suspensions.

  10. 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.

  11. 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.

  12. 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

    of lactic acid bacteria was evaluated regarding their properties with respect to the conversion of lignocellulosic feedstocks. The strains were examined for their ability to utilize xylose and arabinose as well as their resistance towards common inhibitors from pretreated lignocellulosic biomass (furan...... derivatives, phenolic compounds, weak acids). Results: Among 296 tested Lactobacillus and Pediococcus strains, 3 L. pentosus, 1 P. acidilactici and 1 P. pentosaceus isolates were found to be both capable of utilizing xylose and arabinose and highly resistant to the key inhibitors from chemically pretreated...

  13. Microbial community structure and biodegradation activity of particle-associated bacteria in a coal tar contaminated creek.

    Science.gov (United States)

    Debruyn, Jennifer M; Sayler, Gary S

    2009-05-01

    The Chattanooga Creek Superfund site (Chattanooga, TN) is one of the most polluted waterways in the southeastern U.S. with high polycyclic aromatic hydrocarbon (PAH) concentrations in the sediments. PAHs associate with suspended solids in the water column, and may be redeposited onto the floodplain. These suspended particles represent an interesting but understudied environment for PAH-degrading microbial communities. This study tested the hypotheses that particle-associated bacterial (PAB) communities have genotypic potential (PAH-dioxygenase genes) and activity (naphthalene and pyrene mineralization), and can contribute to natural attenuation of PAHs in Chattanooga Creek. Upstream of the Superfund site, mineralization ranged from 0.2 to 2.0% of added 14C-naphthalene and 0 to 0.1% 14C-pyrene (after 40 h), with first order biodegradation rate constants (k1) ranging from 1.09 to 9.18 x 10(-5) h(-1) and 0 to 1.13 x 10(-6) h(-1), respectively. Mineralization was significantly greater in PAB communities within the contaminated zone, with 11.8 to 31.2% 14C-naphthalene (k1 5.34 to 14.2 x 10(-4) h(-1)) and 1.3 to 6.6% 14C-pyrene mineralized (k1 2.89 to 15.0 x 10(-5) h(-1)). Abundances of nagAc (naphthalene dioxygenase) and nidA (pyrene dioxygenase) genes indicated that PAB communities harbored populations with genetic potential for both low- and high-molecularweight PAH degradation, and quantification of Mycobacterium 16S rDNA genes indicated that PAH-degrading mycobacteria are also prevalent in this environment. Phylogenetic comparisons (T-RFLPs) between PAB and sediments indicated these microbial communities were taxonomically distinct, but shared some functional similarities, namely PAH catabolic genotypes, mineralization capabilities, and community structuring along a contamination gradient

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. The influence of condensed tannin structure on rate of microbial mineralization and reactivity to chemical assays.

    Science.gov (United States)

    Norris, Charlotte E; Preston, Caroline M; Hogg, Karen E; Titus, Brian D

    2011-03-01

    We examined how tannin structure influences reactivity in tannin assays and carbon and nitrogen mineralization. Condensed tannins from the foliage of ten tree and shrub species and from pecan shells (Carya illinoensis) had different proportions of: (a) epicatechin (cis) and catechin (trans) isomers, (b) procyanidin (PC) and prodelphinidin (PD) monomers, and (c) different chain lengths. The response of each tannin to several widely used tannin assays was determined. Although there was some variation in response to proanthocyanidin (butanol/HCl) and Folin Ciocalteu assays, we did not deduce any predictable relationship between tannin structure and response to either assay. There was little variation in protein precipitation among the different tannins. To assess biological activity, six of the tannins were incubated with forest humus for 22 days. We determined that, while PC-based tannins remained at least partly extractable for the duration of the incubation, tannins with a high proportion of PD subunits rapidly became unextractable from soil. There was a positive correlation between net nitrogen mineralization and cis chemical structure. Carbon mineralization was enhanced initially by the addition of tannins to humus, but after 22 days, a negative correlation between the proportion of cis subunits and respiration was determined. Overall, we were not able to demonstrate consistent effects of structure on either microbial mineralization or reactivity to chemical assays; such relationships remain elusive.

  19. 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

  20. Microbial community structure and biodegradation activity of particle-associated bacteria in a coal tar contaminated creek

    Energy Technology Data Exchange (ETDEWEB)

    Jennifer M. DeBruyn; Gary S. Sayler [University of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology and Department of Microbiology

    2009-05-01

    The Chattanooga Creek Superfund site (Chattanooga, TN) is one of the most polluted waterways in the southeastern U.S. with high polycyclic aromatic hydrocarbon (PAH) concentrations in the sediments. PAHs associate with suspended solids in the water column, and may be redeposited onto the floodplain. These suspended particles represent an interesting but understudied environment for PAH-degrading microbial communities. This study tested the hypotheses that particle-associated bacterial (PAB) communities have genotypic potential (PAH-dioxygenase genes) and activity (naphthalene and pyrene mineralization), and can contribute to natural attenuation of PAHs in Chattanooga Creek. Upstream of the Superfund site, mineralization ranged from 0.2 to 2.0% of added {sup 14}C-naphthalene and 0 to 0.1% {sup 14}C-pyrene (after 40 h), with first order biodegradation rate constants (k{sub 1}) ranging from 1.09 to 9.18 x 10{sup -5} h{sup -1} and 0 to 1.13 x 10{sup -6} h{sup -1}, respectively. Mineralization was significantly greater in PAB communities within the contaminated zone, with 11.8 to 31.2% {sup 14}C-naphthalene (k{sup 1} 5.34 to 14.2 x 10-4 h{sup -1}) and 1.3 to 6.6% {sup 14}C-pyrene mineralized (k{sub 1} 2.89 to 15.0 x 10{sup -5} h{sup -1}). Abundances of nagAc (naphthalene dioxygenase) and nidA (pyrene dioxygenase) genes indicated that PAB communities harbored populations with genetic potential for both low- and high-molecular weight PAH degradation, and quantification of Mycobacterium 16S rDNA genes indicated that PAH-degrading mycobacteria are also prevalent in this environment. Phylogenetic comparisons (T-RFLPs) between PAB and sediments indicated these microbial communities were taxonomically distinct, but shared some functional similarities, namely PAH catabolic genotypes, mineralization capabilities, and community structuring along a contamination gradient. 38 refs., 4 figs., 2 tabs.

  1. Novel microbial route to synthesize ZnO nanoparticles using Aeromonas hydrophila and their activity against pathogenic bacteria and fungi

    Science.gov (United States)

    Jayaseelan, C.; Rahuman, A. Abdul; Kirthi, A. Vishnu; Marimuthu, S.; Santhoshkumar, T.; Bagavan, A.; Gaurav, K.; Karthik, L.; Rao, K. V. Bhaskara

    2012-05-01

    In the present work, we describe a low-cost, unreported and simple procedure for biosynthesis of zinc oxide nanoparticles (ZnO NPs) using reproducible bacteria, Aeromonas hydrophila as eco-friendly reducing and capping agent. UV-vis spectroscopy, XRD, FTIR, AFM, NC-AFM and FESEM with EDX analyses were performed to ascertain the formation and characterization of ZnO NPs. The synthesized ZnO NPs were characterized by a peak at 374 nm in the UV-vis spectrum. XRD confirmed the crystalline nature of the nanoparticles and AFM showed the morphology of the nanoparticle to be spherical, oval with an average size of 57.72 nm. Synthesized ZnO NPs showed the XRD peaks at 31.75°, 34.37°, 47.60°, 56.52°, 66.02° and 75.16° were identified as (1 0 0), (0 0 2), (1 0 1), (1 0 2), (1 1 0), (1 1 2) and (2 02 ) reflections, respectively. Rietveld analysis to the X-ray data indicated that ZnO NPs have hexagonal unit cell at crystalline level. The size and topological structure of the ZnO NPs was measured by NC-AFM. The morphological characterization of synthesized nanoparticles was analyzed by FESEM and chemical composition by EDX. The antibacterial and antifungal activity was ended with corresponding well diffusion and minimum inhibitory concentration. The maximum zone of inhibition was observed in the ZnO NPs (25 μg/mL) against Pseudomonas aeruginosa (22 ± 1.8 mm) and Aspergillus flavus (19 ± 1.0 mm). Bacteria-mediated ZnO NPs were synthesized and proved to be a good novel antimicrobial material for the first time in this study.

  2. Influences of space, soil, nematodes and plants on microbial community composition of chalk grassland soils

    NARCIS (Netherlands)

    Yergeau, E.; Bezemer, T.M.; Hedlund, K.; Mortimer, S.R.; Kowalchuk, G.A.; Putten, van der W.H.

    2010-01-01

    Microbial communities respond to a variety of environmental factors related to resources (e.g. plant and soil organic matter), habitat (e.g. soil characteristics) and predation (e.g. nematodes, protozoa and viruses). However, the relative contribution of these factors on microbial community composit

  3. 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

  4. Influence of gamma irradiation and storage on the microbial load, chemical and sensory quality of chicken kabab

    Science.gov (United States)

    Al-Bachir, M.; Farah, S.; Othman, Y.

    2010-08-01

    Influence of gamma irradiation and storage on the microbial load, chemical and sensory quality of chicken kabab was investigated. Chicken kabab was treated with 0, 2, 4 or 6 kGy doses of gamma irradiation. Treated and untreated samples were kept in a refrigerator (1-4 °C). Microbiological, chemical and sensory characteristics of chicken kabab were evaluated at 0-5 months of storage. Gamma irradiation decreased the microbial load and increased the shelf-life of chicken kabab. Irradiation did not influence the major constituents of chicken kabab (moisture, protein and fats). No significant differences ( p>0.05) were observed for total acidity between non-irradiated (control) and irradiated chicken kabab. Thiobarbitric acid (TBA) values (expressed as mg malonaldehyde (MDA)/kg chicken kabab) and volatile basic nitrogen (VBN) in chicken kabab were not affected by the irradiation. Sensory evaluation showed no significant differences between irradiated and non-irradiated samples.

  5. 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

  6. [Influence of buffer solutions on the performance of microbial fuel cell electricity generation].

    Science.gov (United States)

    Qiang, Lin; Yuan, Lin-jiang; Ding, Qing

    2011-05-01

    Microbial fuel cell (MFC) is a potential green technology due to its application in wastewater treatment and renewable energy generation. Phosphate buffer solution (PBS) has been commonly used in MFC studies to maintain a suitable pH for electricity generating bacteria and/or to increase the solution conductivity. However, it has some drawbacks using PBS in MFC: One is that the addition of a high concentration of phosphate buffer in MFCs is expensive, especially for the application in wastewater treatment; the other is that phosphates can contribute to the eutrophication conditions of water bodies if the effluents are discharged without the removal of phosphates. By adding PBS buffer as the comparison, the study investigated the effect of borax buffer and in the absence of buffer on the performance of electrical power, coulomb efficiency and effluent pH. 200 mmol/L PBS was the best, conductivity was 1.973 mS/cm,the maximum power density was 36.4 mW/m2 and the maximum coulomb efficiency was 2.92%, effluent pH was almost at (7.00 +/- 0.05). 100 mmol/L borax buffer solution, conductivity was 1.553 mS/cm; the maximum power density was 26.2 mW/m2 coulomb efficiency of 6.26%, which was 2.14 times to PBS and greatly increased the electron recovery efficiency with the effluent pH was (7.35 +/- 0.05). While free buffer solution conductivity was 0.314 mS/cm, maximum power density was 27.64 mW/m2; coulomb efficiency was 2.82% and the effluent pH of approximately 7.43. The electrolyte which in absence of buffer solution conductivity was 1/6 of adding PBS buffer, 1/5 of borax buffer, while its power density lower 8.76 mW/mr2 than adding PBS and higher 1.24 mW/m2 than borax buffer. The results showed that adding the suitable concentration of borax buffer may improve the electron recovery efficiency and under batch conditions, MFC run successfully without adding buffer solution to MFC.

  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. 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.

  9. 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.

  10. Influence of a microbial phytase and zinc oxide on young pig growth performance and serum minerals.

    Science.gov (United States)

    Walk, C L; Srinongkote, S; Wilcock, P

    2013-01-01

    Crossbred pigs (n=288; average age=21±3 d and BW=7.1±0.2 kg) were used in a 42-d trial to determine the influence of a microbial phytase and various doses of ZnO on growth performance and serum minerals. Pigs (6 castrated males or females/pen) were randomly allotted to treatments in a 2×3 factorial arrangement with 2 dietary levels of a microbial phytase (0 or 2,500 phytase units/kg) and 3 dietary levels of supplemental ZnO [0, 1750, or 3,500 mg/kg ZnO (72% Zn)] with 4 pens of castrated males and 4 pens of females per treatment. Diets were formulated to exceed all nutrient requirements, including Ca and P from d 0 to 21 (phase 1) and d 22 to 42 (phase 2). Growth performance, serum Zn, and serum P were not influenced (P>0.05) by a ZnO×phytase interaction during phase 1, phase 2, or overall (d 0 to 42). Phytase increased (P=0.01) ADFI and improved (P=0.02) ADG in phase 1 and improved (P=0.01) overall ADG, regardless of the level of ZnO supplemented. Zinc oxide supplementation linearly reduced (P=0.05) ADG, and ZnO at 3,500 mg/kg reduced (quadratic, P=0.04) G:F in pigs (phase 2). During phase 1, phytase increased serum Ca, but only in the absence of ZnO supplementation, which resulted in a ZnO×phytase interaction (P=0.02). Serum Zn was increased (linear, Psupplementation increased in the diet (phase 1). In phase 2, serum Ca was reduced (linear, P=0.04) and serum Zn was increased (linear, P=0.02) as ZnO supplementation increased in the diet. Phytase supplementation increased (P=0.009) serum Zn and increased (P=0.003) serum P (phase 1). There was no influence of phytase supplementation on serum minerals in phase 2. In summary, supplemental ZnO reduced growth performance in this experiment. Phytase supplementation improved ADG in Ca- and P-adequate diets regardless of the level of ZnO supplemented, which may be attributed to the reduction of phytate as an antinutrient. In addition, through phytate hydrolysis, phytase reduced phytate-Zn interactions and increased

  11. 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.

  12. 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

  13. Understanding the influence of the electrode material on microbial fuel cell performance

    Science.gov (United States)

    Sanchez, David V. P.

    In this thesis, I deploy sets of electrodes into microbial fuel cells (MFC), characterize their performance, and evaluate the influence of both platinum catalysts and carbon-based electrodes on current production. The platinum work centers on improving current production by optimizing the use of the catalyst using nano-fabrication techniques. The carbon-electrode work seeks to determine the influence of the bare electrode on biofilm-anode current production. The development of electrodes for MFCs has boomed over the past decade, however, experiments aimed at identifying how catalyst deposition methods and electrode properties influence current production have been limited. The research conducted here is an attempt to expand this knowledge base for platinum catalysts and carbon electrodes. In the initial chapters (4 and 5), I discuss our attempt to decrease catalyst loadings while increasing current production through the use of platinum nanoparticles. The results demonstrate that incorporating platinum nanoparticles throughout the anode and cathode is an efficient means of increasing MFC current production relative to surface deposition because it increases catalyst surface area. The later chapters (chapters 6 and 7) develop an understanding of the importance of electrode properties (i.e. surface area, activation resistance, conductivity, surface morphology) by electrochemically evaluating well-studied anode-respiring pure cultures on different carbon electrode architectures. Two different architectures are produced by using tubular and platelet shaped constituent materials (i.e. carbon fibers and graphene nanoplatelets) and the morphologies of the electrodes are varied by altering the size of the constituent material. The electrodes are characterized and evaluated in MFCs using either Shewanella oneidensis MR-1 or Geobacter sulfurreducens as the innoculant because their bioelectrochemical physiologies are the most documented in the literature. Using the

  14. 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.

  15. A culture-independent approach to unravel uncultured bacteria and functional genes in a complex microbial community.

    Directory of Open Access Journals (Sweden)

    Yun Wang

    Full Text Available Most microorganisms in nature are uncultured with unknown functionality. Sequence-based metagenomics alone answers 'who/what are there?' but not 'what are they doing and who is doing it and how?'. Function-based metagenomics reveals gene function but is usually limited by the specificity and sensitivity of screening strategies, especially the identification of clones whose functional gene expression has no distinguishable activity or phenotypes. A 'biosensor-based genetic transducer' (BGT technique, which employs a whole-cell biosensor to quantitatively detect expression of inserted genes encoding designated functions, is able to screen for functionality of unknown genes from uncultured microorganisms. In this study, BGT was integrated with Stable isotope probing (SIP-enabled Metagenomics to form a culture-independent SMB toolbox. The utility of this approach was demonstrated in the discovery of a novel functional gene cluster in naphthalene contaminated groundwater. Specifically, metagenomic sequencing of the (13C-DNA fraction obtained by SIP indicated that an uncultured Acidovorax sp. was the dominant key naphthalene degrader in-situ, although three culturable Pseudomonas sp. degraders were also present in the same groundwater. BGT verified the functionality of a new nag2 operon which co-existed with two other nag and two nah operons for naphthalene biodegradation in the same microbial community. Pyrosequencing analysis showed that the nag2 operon was the key functional operon in naphthalene degradation in-situ, and shared homology with both nag operons in Ralstonia sp. U2 and Polaromonas naphthalenivorans CJ2. The SMB toolbox will be useful in providing deep insights into uncultured microorganisms and unravelling their ecological roles in natural environments.

  16. 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.

  17. 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.

  18. Microbial protein in soil: influence of extraction method and C amendment on extraction and recovery.

    Science.gov (United States)

    Taylor, Erin B; Williams, Mark A

    2010-02-01

    The capacity to study the content and resolve the dynamics of the proteome of diverse microbial communities would help to revolutionize the way microbiologists study the function and activity of microorganisms in soil. To better understand the limitations of a proteomic approach to studying soil microbial communities, we characterized extractable soil microbial proteins using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Two methods were utilized to extract proteins from microorganisms residing in a Quitman and Benfield soil: (1) direct extraction of bulk protein from soil and (2) separation of the microorganisms from soil using density gradient centrifugation and subsequent extraction (DGC-EXT) of microbial protein. In addition, glucose and toluene amendments to soil were used to stimulate the growth of a subset of the microbial community. A bacterial culture and bovine serum albumin (BSA) were added to the soil to qualitatively assess their recovery following extraction. Direct extraction and resolution of microbial proteins using SDS-PAGE generally resulted in smeared and unresolved banding patterns on gels. DGC-EXT of microbial protein from soil followed by separation using SDS-PAGE, however, did resolve six to 10 bands in the Benfield but not the Quitman soil. DGC-EXT of microbial protein, but not direct extraction following the addition of glucose and toluene, markedly increased the number of bands (approximately 40) on the gels in both Benfield and Quitman soils. Low recoveries of added culture and BSA proteins using the direct extraction method suggest that proteins either bind to soil organic matter and mineral particles or that partial degradation takes place during extraction. Interestingly, DGC may have been preferentially selected for actively growing cells, as gauged by the 10-100x lower cy19:0/18:1omega7 ratio of the fatty acid methyl esters in the isolated community compared to that for the whole soil. DGC can be used to

  19. 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

  20. 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.

  1. Influence of Bacillus subtilis on the physiological state of wheat and the microbial community of the soil under different rates of nitrogen fertilizers

    Science.gov (United States)

    Pishchik, V. N.; Vorobyev, N. I.; Moiseev, K. G.; Sviridova, O. V.; Surin, V. G.

    2015-01-01

    The effects of inoculation with bacteria Bacillus subtilis strain No. 2 (hereinafter, B. subtilis 2) and of the physical properties of the soil on the physiological state of wheat ( Triticum aestivum L.) plants and the soil microbial community under different rates of nitrogen fertilizers are studied. In the field, the physiological state of wheat was evaluated using the optical vegetation index. It was found that (1) the impact of B. subtilis 2 on plants decreases with an increase in the rate of fertilizers and soil bulk density, (2) the inoculation of wheat with bacteria enhances the resistance of the plant-microbial system to the adverse impact of high rates of nitrogen fertilizers due to the rearrangement of bacteria in rhizosphere ecological niches, and (3) the highest agronomic efficiency of nitrogen fertilizers is observed in wheat inoculation with B. subtilis 2 at the rate of nitrogen fertilization of 120 kg/ha.

  2. 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.

  3. Dual active ionic liquids and organic salts for inhibition of microbially influenced corrosion.

    Science.gov (United States)

    Seter, Marianne; Thomson, Melanie J; Stoimenovski, Jelena; MacFarlane, Douglas R; Forsyth, Maria

    2012-06-18

    We describe a series of novel compounds designed to combat the bacterial growth that leads to microbially induced corrosion on steel in the marine environment. A synergistic effect of the ionic components in these dual active organic salts is demonstrated.

  4. 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

  5. Microbial Relevant Fouling in Membrane Bioreactors: Influencing Factors, Characterization, and Fouling Control

    OpenAIRE

    Anthony G. Fane; Bing Wu

    2012-01-01

    Microorganisms in membrane bioreactors (MBRs) play important roles on degradation of organic/inorganic substances in wastewaters, while microbial deposition/growth and microbial product accumulation on membranes potentially induce membrane fouling. Generally, there is a need to characterize membrane foulants and to determine their relations to the evolution of membrane fouling in order to identify a suitable fouling control approach in MBRs. This review summarized the factors in MBRs that inf...

  6. 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.

  7. 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

  8. The influence of oral bacteria on epithelial cell migration in vitro.

    Science.gov (United States)

    Laheij, Alexa M G A; de Soet, Johannes J; Veerman, Enno C I; Bolscher, Jan G M; van Loveren, Cor

    2013-01-01

    Oral ulcerations often arise as a side effect from chemo- and radiation therapy. In a previous clinical study, Porphyromonas gingivalis was identified as a positive predictor for oral ulcerations after hematopoetic stem cell transplantation, possibly incriminating P. gingivalis in delayed healing of the ulcerations. Therefore, it was tested whether P. gingivalis and its secreted products could inhibit the migration of oral epithelial cells in an in vitro scratch assay. To compare, the oral bacteria Prevotella nigrescens, Prevotella intermedia, Tannerella forsythia, and Streptococcus mitis were included. A standardized scratch was made in a confluent layer of human oral epithelial cells. The epithelial cells were challenged with bacterial cells and with medium containing secretions of these bacteria. Closure of the scratch was measured after 17 h using a phase contrast microscope. P. gingivalis, P. nigrescens, and secretions of P. gingivalis strongly inhibited cell migration. A challenge with 1000 heat-killed bacteria versus 1 epithelial cell resulted in a relative closure of the scratch of 25% for P. gingivalis and 20% for P. nigrescens. Weaker inhibitory effects were found for the other bacteria. The results confirmed our hypothesis that the oral bacteria may be involved in delayed wound healing.

  9. Photodynamic inactivation of multidrug-resistant bacteria in hospital wastewaters: influence of residual antibiotics.

    Science.gov (United States)

    Almeida, Joana; Tomé, João P C; Neves, Maria G P M S; Tomé, Augusto C; Cavaleiro, José A S; Cunha, Ângela; Costa, Liliana; Faustino, Maria A F; Almeida, Adelaide

    2014-04-01

    One environmental concern related to hospital effluents is discharge of them without preliminary treatment. Antimicrobial photodynamic inactivation (PDI) may represent an alternative to the traditional expensive, unsafe and not always effective disinfection methods. The main goal of this work was to assess the efficiency of PDI on clinical multidrug-resistant (MDR) bacteria in hospital wastewaters in order to evaluate its potential use in treating hospital effluents. The efficiency of PDI was assessed using a cationic porphyrin as the photosensitizer (PS), four MDR bacteria either in phosphate buffered saline or in filtrated hospital wastewaters. The synergistic effect of PDI and antibiotics (ampicillin and chloramphenicol) was also evaluated, as well as the effect of the surfactant sodium dodecyl sulfate (SDS). The results show the efficient inactivation of MDR bacteria in PBS (reduction of 6-8 log after 270 min of irradiation at 40 W m(-2) with 5.0 μM of PS). In wastewater, the inactivation of the four MDR bacteria was again efficient and the decrease in bacterial survival starts even sooner. A faster decrease in bacterial survival occurred when PDI was combined with the addition of antibiotics, at sub-inhibitory and inhibitory concentrations, but the SDS did not affect the PDI efficiency. It can be concluded that PDI has potential to be an effective alternative for the inactivation of MDR bacteria in hospital wastewaters and that the presence of antibiotics may enhance its effectiveness.

  10. The Influence of Oral Bacteria on Epithelial Cell Migration In Vitro

    Directory of Open Access Journals (Sweden)

    Alexa M. G. A. Laheij

    2013-01-01

    Full Text Available Oral ulcerations often arise as a side effect from chemo- and radiation therapy. In a previous clinical study, Porphyromonas gingivalis was identified as a positive predictor for oral ulcerations after hematopoetic stem cell transplantation, possibly incriminating P. gingivalis in delayed healing of the ulcerations. Therefore, it was tested whether P. gingivalis and its secreted products could inhibit the migration of oral epithelial cells in an in vitro scratch assay. To compare, the oral bacteria Prevotella nigrescens, Prevotella intermedia, Tannerella forsythia, and Streptococcus mitis were included. A standardized scratch was made in a confluent layer of human oral epithelial cells. The epithelial cells were challenged with bacterial cells and with medium containing secretions of these bacteria. Closure of the scratch was measured after 17 h using a phase contrast microscope. P. gingivalis, P. nigrescens, and secretions of P. gingivalis strongly inhibited cell migration. A challenge with 1000 heat-killed bacteria versus 1 epithelial cell resulted in a relative closure of the scratch of 25% for P. gingivalis and 20% for P. nigrescens. Weaker inhibitory effects were found for the other bacteria. The results confirmed our hypothesis that the oral bacteria may be involved in delayed wound healing.

  11. Microbial colonization of tailed and tailless intrauterine contraceptive devices: influence of the mode of insertion in the rabbit.

    Science.gov (United States)

    Jacques, M; Olson, M E; Costerton, J W

    1986-03-01

    An experimental rabbit model was developed to study the microbial colonization of intrauterine contraceptive devices. Tailed and tailless devices were surgically inserted into into the uterus by two different routes: surgically, directly into the uterine horn, thus avoiding contact with the vaginal and cervical microfloras, or via the vagina and cervix. After 1 to 8 weeks the devices were recovered and prepared for scanning electron microscopy. The surfaces of surgically inserted devices remained uncolonized all through the experiment whereas in those inserted via the cervix microorganisms colonized the core surface as early as 2 weeks after insertion. Our data suggest that in our experimental conditions the mode of insertion appears to be the major factor influencing the microbial colonization of intrauterine contraceptive devices and that the presence of a tail does not seem to play a significant role.

  12. 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

    were collected from the ileum, via intestinal post valve T-caecum (PVTC) cannulas surgically inserted at the ileo-caecal ostium, and from the rectum. The total microbial flora of the ileal samples were analysed for by defining base pair length with terminal restriction fraction length polymorphism (T......-RFLP). The microbial diversity of the coliform flora of the ileal and rectal samples were defined by biochemical fingerprinting. It was observed that many terminal restriction fragments (TRFs) disappeared when new diets were introduced and that some characteristic TRFs were found in the high and low NSP diets......, respectively. Both the total gut microflora and the coliform flora were influenced by the dietary NSP content....

  13. 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.

  14. The influence of grinding and pelleting of feed on the microbial composition and activity in the digestive tract of broiler chickens.

    Science.gov (United States)

    Engberg, R M; Hedemann, M S; Jensen, B B

    2002-09-01

    1. The influence of feed grinding (coarsely or finely ground feed) and feed form (mash or pellets) on the intestinal environment was investigated in a growth experiment with broiler chickens taking the intestinal microflora, intestinal viscosity, and the activities of pancreatic digestive enzymes into consideration. 2. As compared to mash the feeding of pellets was associated with a significantly higher body weight due to increased feed intake and improved feed utilisation. 3. Pellet-fed birds had significantly decreased gizzard weights, a higher gizzard pH and a lower intestinal pH than mash-fed birds. 4. Pellet-fed birds had significantly lower relative pancreas weights and lower activities of pancreatic digestive enzymes (amylase, lipase, chymotrypsin), which indicates the existence of a feedback mechanism, which may have been triggered by the intestinal concentration of enzymatically hydrolysed products or of the respective digestive enzymes. 5. Pellet-fed birds had larger numbers of coliform bacteria and enterococci in the ileum and a reduced number of Clostridium perfringens and lactobacilli in the distal end of the digestive tract (caeca and rectum). Microbial fermentation in terms of volatile fatty acid (VFA) concentration was found to be significantly higher in the caeca of pellet-fed birds than in mash-fed birds.

  15. Influence of 20-year organic and inorganic fertilization on organic carbon accumulation and microbial community structure of aggregates in an intensively cultivated sandy loam soil.

    Science.gov (United States)

    Zhang, Huanjun; Ding, Weixin; He, Xinhua; Yu, Hongyan; Fan, Jianling; Liu, Deyan

    2014-01-01

    To evaluate the long-term effect of compost (CM) and inorganic fertilizer (NPK) application on microbial community structure and organic carbon (OC) accumulation at aggregate scale, soils from plots amended with CM, NPK and no fertilizer (control) for 20 years (1989-2009) were collected. Soil was separated into large macroaggregate (>2,000 μm), small macroaggregate (250-2,000 μm), microaggregate (53-250 μm), silt (2-53 μm) and clay fraction (soil oxygen diffusion coefficient. NPK mainly increased OC in macroaggregates and displayed weaker influence on aggregation. Bacteria distributed in all aggregates, while fungi and actinobacteria were mainly in macroaggregates and microaggregates. The ratio of monounsaturated to branched (M/B) PLFAs, as an indicator for the ratio of aerobic to anaerobic microorganisms, increased inversely with aggregate size. Both NPK and especially CM significantly (Psoil was not only due to a more effective decrease of actinobacteria, but also a decrease of monounsaturated PLFAs and an increase of branched PLFAs. Aggregations under CM appear to alter micro-habitats to those more suitable for anaerobes, which in turn boosts OC accumulation.

  16. Soil pH, total phosphorus, climate and distance are the major factors influencing microbial activity at a regional spatial scale.

    Science.gov (United States)

    Cao, Haichuan; Chen, Ruirui; Wang, Libing; Jiang, Lanlan; Yang, Fen; Zheng, Shixue; Wang, Gejiao; Lin, Xiangui

    2016-05-12

    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 were collected across a region from south to north China (about 1,000 km) to address the questions if microbial activity displays biogeographic patterns and what are driving forces. These samples represented different soil types, land use and climate. Redundancy analysis and nonmetric multidimensional 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 by rainfall, location, temperature, soil pH and soil type and was correlated with microbial activity to some extent. Our results suggest that microbial activities display a clear geographic pattern that is greatly altered by geographic distance and reflected by climate, soil pH and total P over large spatial 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.

  17. 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

  18. 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...... of both copper ion-resistant E. coli and E. faecium strains when samples in rich medium were spread in a thin, moist layer on copper alloys with 85% or greater copper content. E. coli strains were rapidly killed under dry conditions, while E. faecium strains were less affected. Electroplated copper...

  19. 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 Pseu...

  20. FACTORS INFLUENCING IN VITRO KILLING OF BACTERIA BY HEMOCYTES OF THE EASTERN OYSTER (CRASSOSTREA VIRGINICA)

    Science.gov (United States)

    A tetrazolium dye reduction assay was used to study factors governing killing of bacteria by oyster hemocytes. In vitro tests were performed on bacterial strains by using hemocytes from oysters collected from the same location in winter and summer. Vibrio parahaemolyticus strains...

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

    2014-12-01

    Surface soil samples were collected from Antarctic exploration (2010/2011, 2011/2012) at Barton Peninsula, King George Island, West Antarctica to determine the feasible biological alteration of clay minerals in Antarctica where the physical weathering is considered to be a major process. Seven areas (1226-1, 1226-2, 0101-4, 0105-1, 0105-2, 0107-2, 0107-3) from the coast toward the inland were investigated. The duration of exposure of soil samples to the air depending on the retraction of ice to the inland may affect the microbial activity resulting in the biogeochemical mineral alteration. The multiline of techniques for example, X-ray diffraction (XRD), Scanning Electron Microscope (SEM), wet chemistry analysis including the extent of Fe(III) reduction, and batch experiments of microbe-mineral interaction under the low temperature that mimics the Antarctic condition to understand the mechanism of biogeochemical alteration of clay minerals. Clay minerals of smectite, mica, chlorite and kaolinite were detected in the XRD profiles. The variation of relative amount of clay minerals in the regions indicated that the physical/biological alteration might be different depending on the duration of ice retraction. From the batch experiment using Nontronite (NAu-1), moreover, we confirm that Psychrophilic bacteria (Shewanella sp. isolated from King George Island) reduce structural Fe(III) of clay mineral, and occur structural change of smectite at low temperature (4℃ and 15℃). The present study, therefore, would present the feasibility of biological effects on chemical modification through the structural changes in clay mineral in cold environment and suggest a new pathway of Fe-supply into the Antarctic Ocean.

  2. 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...... by rainfall, location, temperature, soil pH and soil type and was correlated with microbial activity to some extent. Our results suggest that microbial activities display a clear geographic pattern that is greatly altered by geographic distance and reflected by climate, soil pH and total P over large spatial...... 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....

  3. Influence of Heavy Metals and PCBs Pollution on the Enzyme Activity and Microbial Community of Paddy Soils around an E-Waste Recycling Workshop

    Directory of Open Access Journals (Sweden)

    Xianjin Tang

    2014-03-01

    Full Text Available Due to the emerging environmental issues related to e-waste there is concern about the quality of paddy soils near e-waste workshops. The levels of heavy metals and PCBs and their influence on the enzyme activity and microbial community of paddy soils obtained from the immediate vicinity of an e-waste workshop were investigated in the present study. The results indicated that the heavy metal and PCB pollution did not differ significantly with an increase of the sampling point distances (5 to 30 m. The concentration of Cd (2.16 mg·kg−1 and Cu (69.2 mg·kg−1 were higher, and the PCB pollution was also serious, ranging from 4.9 to 21.6 μg·kg−1. The highest enzyme activity was found for urease compared to phosphatase and catalase, and a fluctuating trend in soil enzyme activity was observed in soils from different sampling sites. The microbial analysis revealed that there was no apparent correlation between the microbial community and the pollutants. However, a slight influence for soil microbial communities could be found based on DGGE, the Shannon index and PCA analysis. The present study suggests that the contamination stress of heavy metals and PCBs might have a slight influence on microbial activity in paddy soils. This study provides the baseline data for enzyme activities and microbial communities in paddy soil under the influence of mixed contamination.

  4. Influence of heavy metals and PCBs pollution on the enzyme activity and microbial community of paddy soils around an e-waste recycling workshop.

    Science.gov (United States)

    Tang, Xianjin; Hashmi, Muhammad Z; Long, Dongyan; Chen, Litao; Khan, Muhammad I; Shen, Chaofeng

    2014-03-14

    Due to the emerging environmental issues related to e-waste there is concern about the quality of paddy soils near e-waste workshops. The levels of heavy metals and PCBs and their influence on the enzyme activity and microbial community of paddy soils obtained from the immediate vicinity of an e-waste workshop were investigated in the present study. The results indicated that the heavy metal and PCB pollution did not differ significantly with an increase of the sampling point distances (5 to 30 m). The concentration of Cd (2.16 mg·kg-1) and Cu (69.2 mg·kg-1) were higher, and the PCB pollution was also serious, ranging from 4.9 to 21.6 μg·kg-1. The highest enzyme activity was found for urease compared to phosphatase and catalase, and a fluctuating trend in soil enzyme activity was observed in soils from different sampling sites. The microbial analysis revealed that there was no apparent correlation between the microbial community and the pollutants. However, a slight influence for soil microbial communities could be found based on DGGE, the Shannon index and PCA analysis. The present study suggests that the contamination stress of heavy metals and PCBs might have a slight influence on microbial activity in paddy soils. This study provides the baseline data for enzyme activities and microbial communities in paddy soil under the influence of mixed contamination.

  5. 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.

  6. 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.)

  7. 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

  8. 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.

  9. Influence of setup and carbon source on the bacterial community of biocathodes in microbial electrolysis cells

    NARCIS (Netherlands)

    Croesea, E.; Jeremiasse, A.W.; Marshall, I.P.G.; Spormann, A.M.; Euverink, G.J.W.; Geelhoed, J.S.; Stams, A.J.M.; Plugge, C.M.

    2014-01-01

    The microbial electrolysis cell (MEC) biocathode has shown great potential as alternative for expensive metals as catalyst for H2 synthesis. Here, the bacterial communities at the biocathode of five hydrogen producing MECs using molecular techniques were characterized. The setups differed in design

  10. Influence of setup and carbon source on the bacterial community of biocathodes in microbial electrolysis cells

    NARCIS (Netherlands)

    Croese, Elsemiek; Jeremiasse, Adriaan W.; Marshall, Ian P.G.; Spormann, Alfred M.; Euverink, Gert-Jan W.; Geelhoed, Jeanine S.; Stams, Alfons J.M.; Plugge, Caroline M.

    2014-01-01

    The microbial electrolysis cell (MEC) biocathode has shown great potential as alternative for expensive metals as catalyst for H2synthesis. Here, the bacterial communities at the biocathode of five hydrogen producing MECs using molecular techniques were characterized. The setups differed in design (

  11. 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

  12. Influence of Lactic Acid Bacteria on Longevity of Caenorhabditis elegans and Host Defense against Salmonella enterica Serovar Enteritidis▿

    OpenAIRE

    Ikeda, Takanori; Yasui, Chikako; Hoshino, Kaori; Arikawa, Kentaro; Nishikawa, Yoshikazu

    2007-01-01

    This study aimed to develop a convenient model to investigate the senescence of host defenses and the influence of food and nutrition. A small soil nematode, Caenorhabditis elegans, was grown for 3 days from hatching on a lawn of Escherichia coli OP50 as the normal food source, and subsequently some of the nematodes were fed lactic acid bacteria (LAB). The life spans of worms fed LAB were significantly longer than the life spans of those fed OP50. To investigate the effect of age on host defe...

  13. The influence of gene transfer on the lactic acid bacteria evolution

    Directory of Open Access Journals (Sweden)

    Višnja Bačun-Družina

    2009-09-01

    Full Text Available In the case of preparing various dairy products, the exploitation of lactic acid bacteria has been essential in the course of past millennia in all known nations. Numerous comparative analyses of gene and genome sequences reveal that the exchange of genetic material within and between bacterial species is far more general and frequent than has previously been thought. Consequently, the horizontal gene transfer between distant species or within the same species is an important factor in the Lactobacillales evolution. Knowledge about the exchange of lactobacillus genetic information through horizontal gene transfer, mobile genetic elements, and its evolution is very important due to characterizations and stability maintenance of autochthonous as well as industrial lactic acid bacteria strains in dairy products that benefit human health.

  14. Influence of several feeds on bacteria in sheep and goat rumen liquor in vitro.

    Science.gov (United States)

    Gonzalez-Lopez, J; Salmeron, V; Ramos-Cormenzana, A; Silva-Colomer, J; Boza, J

    1990-01-01

    Bacteriological studies were made with in vitro sheep and goat ruminal fluids supplemented with several feeds (alfalfa hay, wheat straw, Agave americana, Opuntia ficus indica and Atriplex nummularia) during anaerobic incubation at 38-39 degrees C. Drastic changes in the bacterial population of sheep ruminal fluids occurred in the presence of different feeds, particularly with addition of feeds of low nutritional quality (wheat straw, A. americana and O. ficus indica). However, the bacterial population in goat rumen liquor was little affected by the addition of the same feeds. These results, which suggest that the rumen bacteria in goats are less affected by different nutritional conditions than the rumen bacteria in sheep, are discussed.

  15. 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

    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 in the rhizo......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...... in the rhizospheres of plants to which only N had been added. Fingerprinting of bacterial communities by length heterogeneity polymerase chain reaction revealed differences in community structure between NP rhizospheres and N rhizospheres as well as aphid-related differences within N rhizospheres. Specifically, a...

  16. Influence of Perfluorooctanoic Acid on the Transport and Deposition Behaviors of Bacteria in Quartz Sand.

    Science.gov (United States)

    Wu, Dan; Tong, Meiping; Kim, Hyunjung

    2016-03-01

    The significance of perfluorooctanoic acid (PFOA) on the transport and deposition behaviors of bacteria (Gram-negative Escherichia coli and Gram-positive Bacillus subtilis) in quartz sand is examined in both NaCl and CaCl2 solutions at pH 5.6 by comparing both breakthrough curves and retained profiles with PFOA in solutions versus those without PFOA. All test conditions are found to be highly unfavorable for cell deposition regardless of the presence of PFOA; however, 7%-46% cell deposition is observed depending on the conditions. The cell deposition may be attributed to micro- or nanoscale roughness and/or to chemical heterogeneity of the sand surface. The results show that, under all examined conditions, PFOA in suspensions increases cell transport and decreases cell deposition in porous media regardless of cell type, presence or absence of extracellular polymeric substances, ionic strength, and ion valence. We find that the additional repulsion between bacteria and quartz sand caused by both acid-base interaction and steric repulsion as well as the competition for deposition sites on quartz sand surfaces by PFOA are responsible for the enhanced transport and decreased deposition of bacteria with PFOA in solutions.

  17. 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.

  18. 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

  19. 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.

  20. Identifying the major influences on the microbial composition of roof harvested rainwater and the implications for water quality.

    Science.gov (United States)

    Evans, C A; Coombes, P J; Dunstan, R H; Harrison, T

    2007-01-01

    Perceptions of the quality of roof harvested rainwater remain an impediment to widespread implementation of rainwater tanks on urban allotments. Previous literature reports on roof water quality have given little consideration to the relative significance of airborne environmental micro-organisms to roof catchment contamination and the issue of tank water quality. This paper outlines the findings of a recent study into the influence of weather on roof water contamination conducted at an urban housing development in Newcastle, on the east coast of Australia. Samples of direct roof run-off were collected during a number of separate rainfall events, and microbial counts were matched to climatic data corresponding to each of the monitored events. Roof run-off contamination was found to be under the strong influence of both wind speed and direction. The preliminary findings of an investigation currently under way into the microbial diversity of rainwater harvesting systems have also been presented. The results indicate that the composition of organisms present varied considerably from source to source and throughout the collection system. In all cases, evidence of faecal contamination was found to be negligible. The implications of these findings to the issues of tank water quality, health risk analysis and monitoring protocols have been discussed.

  1. 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.

  2. Influence of Sedimentary and Seagrass Microbial Communities on Shallow-Water Benthic Optical Properties

    Science.gov (United States)

    2008-09-30

    Similarly, determine the biomass, composition, and temporal variation of microorganisms epiphytic on seagrass blades at Lee Stocking Island (turtle...following section. 1) In October, we will submit a manuscript, authored by Drake, Dobbs, and Zimmerman, and entitled “Effects of epiphyte load on... epiphytes collected from LSI and Monterey Bay. There are two types of lipid analyses we have performed. The first yields a microbial biomass value

  3. Influence of a bacteriophage on the population dynamics of toxic dinoflagellates by lysis of algicidal bacteria.

    Science.gov (United States)

    Cai, Wenwei; Wang, Hui; Tian, Yun; Chen, Feng; Zheng, Tianling

    2011-11-01

    A lytic phage (øZCW1) was isolated from an algicidal bacterium Pseudoalteromonas sp. strain SP48 that specifically kills the toxic dinoflagellate Alexandrium tamarense. We demonstrated that øZCW1 could trigger the growth of A. tamarense by inhibiting the growth of algicidal bacterium SP48. In contrast, the growth of A. tamarense was suppressed when cocultured with either SP48 or the øZCW1-resistant mutant of SP48. This study provides the first evidence of the indirect impact of bacteriophage on bloom-forming microalgae via phage lysis of alga-killing bacteria.

  4. 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.

  5. The Influence and Role of Microbial Factors in Autoimmune Kidney Diseases: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Andreas Kronbichler

    2015-01-01

    Full Text Available A better understanding of the pathophysiology of autoimmune disorders is desired to allow tailored interventions. Despite increased scientific interest a direct pathogenic factor in autoimmune renal disease has been described only in a minority like membranous nephropathy or ANCA-associated vasculitis. Nonetheless the initial step leading to the formation of these antibodies is still obscure. In this review we will focus on the possible role of microbial factors in this context. Staphylococcus aureus may be a direct pathogenetic factor in granulomatosis with polyangiitis (GPA. Chronic bacterial colonization or chronic infections of the upper respiratory tract have been proposed as trigger of IgA vasculitis and IgA nephropathy. Interventions to remove major lymphoid organs, such as tonsillectomy, have shown conflicting results but may be an option in IgA vasculitis. Interestingly no clear clinical benefit despite similar local colonization with bacterial strains has been detected in patients with IgA nephropathy. In systemic lupus erythematosus injection of bacterial lipopolysaccharide induced progressive lupus nephritis in mouse models. The aim of this review is to discuss and summarize the knowledge of microbial antigens in autoimmune renal disease. Novel methods may provide insight into the involvement of microbial antigens in the onset, progression, and prognosis of autoimmune kidney disorders.

  6. 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.

  7. Influence of oxygen exclusion and temperature on pathogenic bacteria levels and sensory characteristics of packed ostrich steaks throughout refrigerated storage.

    Science.gov (United States)

    González-Montalvo, Beatriz; Capita, Rosa; Guevara-Franco, José Alfredo; Prieto, Miguel; Alonso-Calleja, Carlos

    2007-06-01

    Ostrich steaks (290) were obtained from Iliofibularis muscles. For microbiological and pH determinations, samples were inoculated with Listeria monocytogenes NCTC 11994 (80 steaks) or Escherichia coli ATCC 12806 (80), then air- or vacuum-packed and stored at either 4±1°C or 10±1°C. Analyses were carried out on days 0, 3, 6 and 9 of storage. For sensory evaluation, samples (130) were air- or vacuum-packed and stored at 4±1°C or at 10±1°C. Sensory attributes (odour, colour, drip loss, texture and general acceptability) were scored by six untrained judges using an unstructured nine-point hedonic scale on eleven sampling days (0, 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30). Increases in microbial counts (log(10)cfu/g) were observed throughout storage in all groups of samples for both L. monocytogenes (from 6.39±0.43-6.62±0.32 at day 0 to 8.87±0.19-9.64±0.43 at day 9) and E. coli (from 5.57±0.15-5.68-0.40 to 7.79±0.96-9.64±0.17). Gas atmosphere influenced microbial counts from day 3 of storage with lower (Pair-packed samples at 10°C (L. monocytogenes) or at 4 and 10°C (E. coli). Storage temperature significantly influenced bacterial counts throughout storage, especially in air-packed samples. Lower pH values in vacuum- than in air-packed samples were observed from day 6. Both effects (gas atmosphere and temperature) influenced the hedonic scores, with higher values assigned to vacuum-packed samples for most attributes (with the exception of drip loss) and sampling days. A marked influence of storage temperature on sensorial scores was obtained in air-packaged ostrich steaks. The shelf-life (time until the average general acceptability score fell below 5) was 6 (air-packed samples), 9 (vacuum-packed, 10°C), or 12 days (vacuum-packed, 4°C). The results being reported here suggest the importance of both oxygen exclusion and storage at low temperatures to reduce microbiological risks and improve the acceptability of ostrich meat. However, the short shelf

  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. 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.

  10. 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.

  11. 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.

  12. The reactive transport of trichloroethene is influenced by residence time and microbial numbers

    Science.gov (United States)

    Haest, P. J.; Philips, J.; Springael, D.; Smolders, E.

    2011-01-01

    The dechlorination rate in a flow-through porous matrix can be described by the species specific dechlorination rate observed in a liquid batch unless mass transport limitations prevail. This hypothesis was examined by comparing dechlorination rates in liquid batch with that in column experiments at various flow rates (3-9-12 cm day - 1 ). Columns were loaded with an inoculated sand and eluted with a medium containing 1 mM trichloroethene (TCE) for 247 days. Dechlorination in the column treatments increased with decreasing flow rate, illustrating the effect of the longer residence time. Zeroth order TCE or cis-DCE degradation rates were 4-7 folds larger in columns than in corresponding batch systems which could be explained by the higher measured Geobacter and Dehalococcoides numbers per unit pore volume in the columns. The microbial numbers also explained the variability in dechlorination rate among flow rate treatments marked by a large elution of the dechlorinating species' yield as flow increased. Stop flow events did not reveal mass transport limitations for dechlorination. We conclude that flow rate effects on reactive transport of TCE in this coarse sand are explained by residence time and by microbial transport and that mass transport limitations in this porous matrix are limited.

  13. Influence of moisture content on microbial activity and silage quality during ensilage of food processing residues.

    Science.gov (United States)

    Zheng, Yi; Yates, Matthew; Aung, Hnin; Cheng, Yu-Shen; Yu, Chaowei; Guo, Hongyun; Zhang, Ruihong; Vandergheynst, Jean; Jenkins, Bryan M

    2011-10-01

    Seasonally produced biomass such as sugar beet pulp (SBP) and tomato pomace (TP) needs to be stored properly to meet the demand of sustainable biofuel production industries. Ensilage was used to preserve the feedstock. The effect of moisture content (MC) on the performance of ensilage and the relationship between microorganism activities and MC were investigated. For SBP, MC levels investigated were 80, 55, 30, and 10% on a wet basis. For TP, MC levels investigated were 60, 45, 30, and 10%. Organic acids, ethanol, ammonia, pH and water soluble carbohydrates (WSC) were measured to evaluate the silage quality. Ensilage improved as the MC decreased from 80 to 55% for SBP and from 60 to 45% for TP. When the MC decreased to 30%, a little microbial activity was detected for both feedstocks. Storage at 10% MC prevented all the microbial activity. The naturally occurring microorganisms in TP were found to preserve TP during silage and were isolated and determined by polymerase chain reaction (PCR). The results suggest that partial drying followed by ensilage may be a good approach for stabilization of food processing residues for biofuels production.

  14. Bioremediation of oil refinery sludge by landfarming in semiarid conditions: influence on soil microbial activity.

    Science.gov (United States)

    Marin, J A; Hernandez, T; Garcia, C

    2005-06-01

    Bioremediation of a refinery sludge containing hydrocarbons in a semi-arid climate using landfarming techniques is described. The objective of this study was to assess the ability of this technique to reduce the total hydrocarbon content added to the soil with the refinery sludge in semiarid climate (low rain and high temperature). In addition, we have evaluated the effect of this technique on the microbial activity of the soil involved. For this, biological parameters (carbon fractions, microbial biomass carbon, basal respiration and ATP) and biochemical parameters(different enzymatic activities) were determined. The results showed that 80% of the hydrocarbons were eliminated in eleven months, half of this reduction taking place during the first three months. The labile carbon fractions, MBC, basal respiration and ATP of the soils submitted to landfarming showed higher values than the control soil during the first months of the process, although these values fell down by the end of the experimental period as the hydrocarbons were degraded by mineralisation. All the enzymatic activities studied: oxidoreductases such as dehydrogenase activity, and hydrolases of C(beta-glucosidase activity) and N Cycle (urease and protease) showed higher values in the soils amended with the refinery sludge than in the control. As in the case of the previous parameters, these value fell down as the bioremediation of the hydrocarbons progressed, many of them reaching levels similar to those of the control soil after eleven months.

  15. [Influence of ionizing radiation of low intensity on the processes of reproduction, aging and dying off of Escherichia coli bacteria].

    Science.gov (United States)

    Morozov, I I; Petin, V G; Morozova, G V

    2002-01-01

    The influence of 60Co gamma-ray irradiation of low intensity (0.1-0.4, 0.76 x 10(3) microGy/h) on the processes of reproduction, aging and dying off of E. coli B/r and E. coli BS-1 bacteria have been investigated. It was shown that the reproduction of this bacteria strains was not dependent on the dose rate in the range 0.1-0.4 microGy/h. It was shown in comparison with the irradiated E. coli B/r cells dynamics of the aging and dying off of the irradiated E. coli BS-1 is decreased in the process of prolonged (about 190 days) irradiation with a dose rate of 0.76 x 10(3) microGy/h. It is proposed the relationship between the revealed phenomenon of the decrease in the intensity of the irradiated E. coli BS-1 cell aging and dying and the Vavilov-Cerenkov emission.

  16. 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.

  17. 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

    Background and Objectives Neutrophil extracellular trap (NET) release has generally been studied in the absence of serum, or at low concentrations of untreated or heat-inactivated serum. The influence of serum complement on NET release therefore remains unclear. We examined the DNA release induce...

  18. 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.

  19. Cathodic protection of XL 52 steel under the influence of sulfate reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Esquivel, R. Garcia [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, Mexico, D.F. 07730 (Mexico); Departamento de lngenieria Metalurgica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico); Olivares, G. Zavala; Gayosso, M.J. Hernandez; Trejo, A. Gayosso [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, Mexico, D.F. 07730 (Mexico)

    2011-01-15

    The effect of sulfate reducing bacteria (SRB) upon the cathodic protection of XL 52 steel was determined, in order to identify if the potential value of -0.950 V versus copper/copper sulfate electrode is good enough to protect the metal surface. During the experiments, different operational parameters were monitored: hydrogen sulfide production, iron concentration, electrolyte alkalinity, microorganisms' population, as well as the metal surface damage. At the same time, the corrosion rate was determined using two electrochemical techniques: polarization resistance (PR) and electrochemical impedance spectroscopy (EIS). According to the results, it was observed that the protection potential of -0.950 V versus copper/copper sulfate electrode is not enough to control the microbiologically induced corrosion. This situation is reinforced by the fact that significant iron concentration was found in the electrolyte. The microbiological activity is not affected by the protection potential. On the contrary, the population growth is slightly strengthened. The alkalinity generated by the applied potential did not stop the SRB growth. A type of localized corrosion was developed during the experiments with microorganisms, even when the protection potential was applied to the system. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. 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.

  1. 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

  2. The Influence of Age and Gender on Skin-Associated Microbial Communities in Urban and Rural Human Populations.

    Directory of Open Access Journals (Sweden)

    Shi Ying

    Full Text Available Differences in the bacterial community structure associated with 7 skin sites in 71 healthy people over five days showed significant correlations with age, gender, physical skin parameters, and whether participants lived in urban or rural locations in the same city. While body site explained the majority of the variance in bacterial community structure, the composition of the skin-associated bacterial communities were predominantly influenced by whether the participants were living in an urban or rural environment, with a significantly greater relative abundance of Trabulsiella in urban populations. Adults maintained greater overall microbial diversity than adolescents or the elderly, while the intragroup variation among the elderly and rural populations was significantly greater. Skin-associated bacterial community structure and composition could predict whether a sample came from an urban or a rural resident ~5x greater than random.

  3. 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.

    , in hydrolysing organic matter and in influencing the dynamics of phytoplankton.  ACKNOWLEDGEMENTS This document is an output from the UKIERI (UK- INDIA Education and Research Initiative) project entitled ‘Development of Methodology for Biological... Assessment of Ballast Water Management Systems’ funded by the British Council, the UK Department for Education and Skills (DfES), Office of Science and Innovation, the FCO, Scotland, Northern Ireland, Wales, GSK, BP, Shell and BAE for the benefit...

  4. Influence of setup and carbon source on the bacterial community of biocathodes in microbial electrolysis cells.

    Science.gov (United States)

    Croese, Elsemiek; Jeremiasse, Adriaan W; Marshall, Ian P G; Spormann, Alfred M; Euverink, Gert-Jan W; Geelhoed, Jeanine S; Stams, Alfons J M; Plugge, Caroline M

    2014-01-01

    The microbial electrolysis cell (MEC) biocathode has shown great potential as alternative for expensive metals as catalyst for H2 synthesis. Here, the bacterial communities at the biocathode of five hydrogen producing MECs using molecular techniques were characterized. The setups differed in design (large versus small) including electrode material and flow path and in carbon source provided at the cathode (bicarbonate or acetate). A hydrogenase gene-based DNA microarray (Hydrogenase Chip) was used to analyze hydrogenase genes present in the three large setups. The small setups showed dominant groups of Firmicutes and two of the large setups showed dominant groups of Proteobacteria and Bacteroidetes. The third large setup received acetate but no sulfate (no sulfur source). In this setup an almost pure culture of a Promicromonospora sp. developed. Most of the hydrogenase genes detected were coding for bidirectional Hox-type hydrogenases, which have shown to be involved in cytoplasmatic H2 production.

  5. 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.

  6. The influence of whey protein concentrate on growth and survival of probiotic bacteria in whey

    Directory of Open Access Journals (Sweden)

    Ljubica Tratnik

    2008-08-01

    Full Text Available 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 hour shorter (∼ 14 hours compared to the fermentation of whey without WPC addition (∼ 15 hours. The viable cells count of Lactobacilus acidophilus La-5 was better in whey with 3% of WPC addition (Δlog CFU/mL = 2.1 compared to whey without WPC addition (Δlog CFU/mL = 1.7 . Addition of whey protein concentrate did not influence significantly on growth of Bifidobacterium animalis subsp. lactis BB-12 in whey, and also it did not influence the survival of both probiotic species during 28 days of cool storage (at 4 °C. Whey enriched with WPC had slightly higher titratable acidity during fermentation and storage compared to whey without WPC addition.

  7. 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

  8. 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...

  9. 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.

  10. 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...

  11. Ileal MUC2 gene expression and microbial population, but not growth performance and immune response, are influenced by in ovo injection of probiotics in broiler chickens.

    Science.gov (United States)

    Majidi-Mosleh, A; Sadeghi, A A; Mousavi, S N; Chamani, M; Zarei, A

    2017-02-01

    1. The objective of present study was to evaluate the effects of intra-amniotic injection of different probiotic strains (Bacillus subtilis, Enterococcus faecium and Pediococcus acidilactici) on the intestinal MUC2 gene expression, microbial population, growth performance and immune response in broiler chicken. 2. In a completely randomised design, different probiotic strains were injected into the amniotic fluid of the 480 live embryos (d 18 of incubation), with 4 treatments and 5 replicates. Ileal MUC2 gene expression, microbial profile, growth performance and immune response were determined. 3. Injection of probiotic strains, especially B. subtilis, had significant effect on expression of the MUC2 on d 21 of incubation and d 3 post-hatch, but not on d 19 of incubation. 4. Injection of the probiotic strains decreased significantly the Escherichia coli population and increased the lactic acid bacteria population during the first week post-hatch. 5. Inoculation of probiotics had no significant effect on antibody titres against Newcastle disease virus, antibody titres against sheep red blood cell and cell-mediated immune response of chickens compared to control. 6. In ovo injection of the probiotic strains had no significant effect on growth performance of broiler chickens. 7. It was concluded that injection of probiotic bacteria especially B. subtilis into the amniotic fluid has a beneficial effect on ileal MUC2 gene expression and bacteria population during the first week post-hatch, but has no effect on growth performance and immune response in broiler chickens.

  12. Combined factors influencing the aggregation and deposition of nano-TiO2 in the presence of humic acid and bacteria.

    Science.gov (United States)

    Chowdhury, Indranil; Cwiertny, David M; Walker, Sharon L

    2012-07-03

    This study investigates the contributions of natural organic matter (NOM) and bacteria to the aggregation and deposition of TiO(2) nanoparticles (TNPs) in aquatic environments. Transport experiments with TNPs were conducted in a microscopic parallel plate system and a macroscopic packed-bed column using fluorescently tagged E. coli as a model organism and Suwannee River Humic Acid as a representative NOM. Notably, TNPs were labeled with fluorescein isothiocyanate allowing particles and cells to be simultaneously visualized with a fluorescent microscope. Results from both experimental systems revealed that interactions among TNPs, NOM, and bacteria exhibited a significant dependence on solution chemistry (pH 5 and 7) and ion valence (K(+) and Ca(2+)), and that these interactions subsequently affect TNPs deposition. NOM and E. coli significantly reduced deposition of TNPs, with NOM having a greater stabilizing influence than bacteria. Ca(2+) ions played a significant role in these interactions, promoting formation of large clusters of TNPs, NOM, and bacteria. TNPs transport in the presence of both NOM and E. coli resulted in much less deposition than in the presence of NOM or E. coli alone, indicating a complex combination of interactions involved in stabilization. Generally, over the aquatic conditions considered, the extent of TNPs deposition follows: without NOM or bacteria > with bacteria only > with NOM only > combined bacteria and NOM. This trend should allow better prediction of the fate of TNPs in complex aquatic systems.

  13. 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.

  14. 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.

  15. 2种中药制剂微生物限度与控制菌方法验证%Method verification of microbial limit and control bacteria for two kinds of Chinese patent drugs

    Institute of Scientific and Technical Information of China (English)

    闵红; 唐娜; 尹良君

    2013-01-01

    目的 建立六味地黄胶囊与杞菊地黄胶囊微生物限度与控制菌的检查方法.方法 采用常规法与培养基稀释法对2种中药制剂进行微生物限度方法验证,采用直接接种法进行控制菌方法验证.结果 建立了2种中药制剂的微生物限度与控制菌检查方法.结论 六味地黄胶囊采用培养基稀释法(0.5 mL/皿)测定细菌数,常规法测定霉菌及酵母菌数;杞菊地黄胶囊采用培养基稀释法(0.2 mL/皿)测定细菌数,培养基稀释法(0.5 mL/皿)测定霉菌及酵母菌数.采用直接接种法对2种中药制剂进行控制菌(大肠埃希菌与大肠菌群)检测.%Objective To estabilish methods of the microbial limit and control bacteria tests for Liuweidihuang Capsules and Qijudi-huang Capsules. Methods Routine method and medium diluting method were adopted for the verification of microbial methodology, direct inoculation method for control bacteria. Results The methods of the microbial limit and control bacteria tests for two kinds of Chinese patent drugs were estabilished. Conclusion Bacterial count of Liuweidihuang Capsules could adopt the medium diluting method (0. 5 mL/plant) , while yeast and mold count could adopt the routine method. Bacterial count of Qijudihuang Capsules could adopt the medium diluting method (0. 2 mL/plant) , while yeast and mold count could adopt the medium diluting method (0. 5 mL/plant). Direct inoculation method could be adopted for detecting the control bacteria for the two kinds of Chinese patent preparations.

  16. 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.

  17. 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

  18. Influence of carbohydrate source on ruminal fermentation characteristics, performance, and microbial protein synthesis in dairy cows.

    Science.gov (United States)

    Gozho, G N; Mutsvangwa, T

    2008-07-01

    Eight multiparous Holstein cows (676 +/- 57 kg of body weight; 121 +/- 17 d-in-milk) were used in a replicated 4 x 4 Latin square design to determine the effects of 4 sources of carbohydrate on milk yield and composition, ruminal fermentation, and microbial N flow to the duodenum. Four cows in one of the Latin squares were fitted with permanent ruminal cannulae. Diets contained (DM basis) 50% forage in combinations of alfalfa hay and barley silage, and 50% concentrate. The concentrate portion of the diets contained barley, corn, wheat, or oats grain as the primary source of carbohydrate. Intake of DM ranged from 24.0 to 26.2 kg/d, and it tended to be lower in cows fed the wheat-based diet compared with those fed the barley-based diet; consequently, milk yield tended to be lower in cows fed the wheat-based diet compared with those fed the barley-based diet. Cows fed the barley- or wheat-based diets had a lower milk fat content compared with those fed the corn-based diet. Ruminal fermentation characteristics were largely unaffected by the source of dietary carbohydrate, with similar ruminal pH and volatile fatty acid and ammonia concentrations for the first 6 h after the morning feeding. Dietary treatment did not affect total tract apparent digestibility of DM, organic matter, and neutral detergent fiber; however, total tract apparent digestibility of starch in cows fed the oats-based diet was higher compared with those fed the corn-and wheat-based diets. Nitrogen that was used for productive purposes (i.e., N secreted in milk + N apparently retained by the cow) tended to be lower in cows fed the wheat-based diet compared with cows fed the barley-, corn-, or oats-based diets. Urinary purine derivative (PD) excretion was similar in cows fed the barley-, corn-, and wheat-based diets; however, purine derivative excretion was higher in cows fed the barley-based diet compared with those fed the oats-based diet. Consequently, estimated microbial N flow to the duodenum was

  19. Temperature and relative humidity influence the microbial and physicochemical characteristics of Camembert-type cheese ripening.

    Science.gov (United States)

    Leclercq-Perlat, M-N; Sicard, M; Trelea, I C; Picque, D; Corrieu, G

    2012-08-01

    To evaluate the effects of temperature and relative humidity (RH) on microbial and biochemical ripening kinetics, Camembert-type cheeses were prepared from pasteurized milk seeded with Kluyveromyces marxianus, Geotrichum candidum, Penicillium camemberti, and Brevibacterium aurantiacum. Microorganism growth and biochemical changes were studied under different ripening temperatures (8, 12, and 16°C) and RH (88, 92, and 98%). The central point runs (12°C, 92% RH) were both reproducible and repeatable, and for each microbial and biochemical parameter, 2 kinetic descriptors were defined. Temperature had significant effects on the growth of both K. marxianus and G. candidum, whereas RH did not affect it. Regardless of the temperature, at 98% RH the specific growth rate of P. camemberti spores was significantly higher [between 2 (8°C) and 106 times (16°C) higher]. However, at 16°C, the appearance of the rind was no longer suitable because mycelia were damaged. Brevibacterium aurantiacum growth depended on both temperature and RH. At 8°C under 88% RH, its growth was restricted (1.3 × 10(7) cfu/g), whereas at 16°C and 98% RH, its growth was favored, reaching 7.9 × 10(9) cfu/g, but the rind had a dark brown color after d 20. Temperature had a significant effect on carbon substrate consumption rates in the core as well as in the rind. In the rind, when temperature was 16°C rather than 8°C, the lactate consumption rate was approximately 2.9 times higher under 88% RH. Whatever the RH, temperature significantly affected the increase in rind pH (from 4.6 to 7.7 ± 0.2). At 8°C, an increase in rind pH was observed between d 6 and 9, whereas at 16°C, it was between d 2 and 3. Temperature and RH affected the increasing rate of the underrind thickness: at 16°C, half of the cheese thickness appeared ripened on d 14 (wrapping day). However, at 98% RH, the underrind was runny. In conclusion, some descriptors, such as yeast growth and the pH in the rind, depended solely on

  20. 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.

  1. Do climate and soil influence phenotypic variability in leaf litter, microbial decomposition and shredder consumption?

    Science.gov (United States)

    Graça, M A S; Poquet, J M

    2014-03-01

    We tested the hypothesis that water stress and soil nutrient availability drive leaf-litter quality for decomposers and detritivores by relating chemical and physical leaf-litter properties and decomposability of Alnus glutinosa and Quercus robur, sampled together with edaphic parameters, across wide European climatic gradients. By regressing principal components analysis of leaf traits [N, P, condensed tannins, lignin, specific leaf area (SLA)] against environmental and soil parameters, we found that: (1) In Q. robur the condensed tannin and lignin contents increased and SLA decreased with precipitation, annual range of temperature, and soil N content, whereas leaf P increased with soil P and temperature; (2) In A. glutinosa leaves N, P, and SLA decreased and condensed tannins increased with temperature, annual range of temperature, and decreasing soil P. On the other hand, leaf P and condensed tannins increased and SLA decreased with minimum annual precipitation and towards sites with low temperature. We selected contrasting leaves in terms of quality to test decomposition and invertebrate consumption. There were intraspecific differences in microbial decomposition rates (field, Q. robur) and consumption by shredders (laboratory, A. glutinosa). We conclude that decomposition rates across ecosystems could be partially governed by climate and soil properties, affecting litter quality and therefore decomposers and detritivores. Under scenarios of global warming and increased nutrients, these results suggest we can expect species-specific changes in leaf-litter properties most likely resulting in slow decomposition with increased variance in temperatures and accelerated decomposition with P increase.

  2. 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.

  3. Microwave radiation and reactor design influence microbial communities during methane fermentation.

    Science.gov (United States)

    Cydzik-Kwiatkowska, Agnieszka; Zieliński, Marcin; Jaranowska, Paulina

    2012-09-01

    The effect of reactor design and method of heating on the efficiency of methane fermentation and composition of microbial communities, especially methanogenic Archaea, were determined. The research was carried out using submerge- and trickling-bed reactors fed with wastewater and the heat supply into the reactors included a convection heating method and microwave radiation. The polymerase chain reaction-denaturing gradient gel electrophoresis and relative real-time PCR were used in order to assess the biofilm communities. The best fermentation results and the highest abundance of methanogenic Archaea in biomass were observed in microwave heated trickling-bed reactors. The research proved that in reactors of identical design, the application of microwaves enabled a higher fermentation efficiency to be obtained and simultaneously increased the diversity of methanogenic Archaea communities that favors process stability. All the identified sequences of Archaea belonged to Methanosarcina sp., suggesting that species from this genera are susceptible to non-thermal effects of microwaves. There were no effects from microwaves on the bacterial communities in both types of reactors, however, the bacterial species composition varied in the reactors of different design.

  4. 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...

  5. Influence of thymol and a urease inhibitor on coliform bacteria, odor, urea, and methane from a swine production manure pit.

    Science.gov (United States)

    Varel, Vincent H; Wells, James E

    2007-01-01

    Pathogens, ammonia, odor, and greenhouse gas emissions are serious environmental concerns associated with swine production. This study was conducted in two manure pits (33,000 L each) to determine the influence of 1.5 or 3.0 g thymol L(-1) and 80 mg L(-1) urease inhibitor amendments on urea accumulation, coliform bacteria, odor, and methane emission. Each experiment lasted 18 or 19 d, during which time 30 to 36 250-mL samples (six per day) were withdrawn from underneath each pit and analyzed for urea, thymol, volatile fatty acids, coliform bacteria, and Campylobacter. At the end of each experiment, six 50-g samples from each pit were placed in serum bottles, and gas volume and composition were determined periodically for 28 d. Compared with the control pit, volatile fatty acids production was reduced 64 and 100% for the thymol amendments of 1.5 and 3.0 g L(-1), respectively. Viable coliform cells were reduced 4.68 and 5.88 log10 colony-forming units kg(-1) of slurry for the 1.5 and 3.0 g thymol L(-1), respectively, and Escherichia coli were reduced 4.67 and 5.01 log10 colony-forming units kg(-1) of slurry, respectively. Campylobacter was not detected in the pits treated with thymol, in contrast to 63% of the samples being positive for the untreated pit. Urea accumulated in the treated pits from Day 3 to 6. Total gas production from serum bottles was reduced 65 and 76% for thymol amendments of 1.5 and 3.0 g L(-1), respectively, and methane was reduced 78 and 93%, respectively. These results suggest that thymol markedly reduces pathogens, odor, and greenhouse gas emissions from a swine production facility. The urease inhibitor produced a temporary response in conserving urea.

  6. 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.

  7. Bacterial effects on arbuscular mycorrhizal fungi and mycorrhiza development as influenced by the bacteria, fungi, and host plant.

    Science.gov (United States)

    Pivato, Barbara; Offre, Pierre; Marchelli, Sara; Barbonaglia, Bruno; Mougel, Christophe; Lemanceau, Philippe; Berta, Graziella

    2009-02-01

    Bacterial strains from mycorrhizal roots (three belonging to Comamonadaceae and one to Oxalobacteraceae) and from non-mycorrhizal roots (two belonging to Comamonadaceae) of Medicago truncatula and two reference strains (Collimonas fungivorans Ter331 and Pseudomonas fluorescens C7R12) were tested for their effect on the in vitro saprophytic growth of Glomus mosseae BEG12 and on its colonization of M. truncatula roots. Only the Oxalobacteraceae strain, isolated from barrel medic mycorrhizal roots, and the reference strain P. fluorescens C7R12 promoted both the saprophytic growth and root colonization of G. mosseae BEG12, indicating that they acted as mycorrhiza helper bacteria. Greatest effects were achieved by P. fluorescens C7R12 and its influence on the saprophytic growth of G. mosseae was compared to that on Gigaspora rosea BEG9 to determine if the bacterial stimulation was fungal specific. This fungal specificity, together with plant specificity, was finally evaluated by comparing bacterial effects on arbuscular mycorrhizal symbiosis when each of the fungal species was inoculated to two different plant species (M. truncatula and Lycopersicon esculentum). The results obtained showed that promotion of saprophytic growth by P. fluorescens C7R12 was expressed in vitro towards G. mosseae but not towards G. rosea. Bacterial promotion of mycorhization was also expressed towards G. mosseae, but not G. rosea, in roots of M. truncatula and L. esculentum. Taken together, results indicated that enhancement of arbuscular mycorrhiza development was only induced by a limited number of bacteria, promotion by the most efficient bacterial strain being fungal and not plant specific.

  8. 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

  9. 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

  10. Influence of geochemical properties and land-use types on the microbial reduction of Fe(III) in subtropical soils.

    Science.gov (United States)

    Liu, Chengshuai; Wang, Yongkui; Li, Fangbai; Chen, Manjia; Zhai, Guangshu; Tao, Liang; Liu, Chuanping

    2014-08-01

    Microbial Fe(III) reduction significantly impacts the geochemical processes and the composition of most subsurface soils. However, up to now, the factors influencing the efficiency of Fe(III) reduction in soils have not been fully described. In this study, soil Fe(III) reduction processes related to geochemical properties and land-use types were systematically investigated using iron-rich soils. The results showed that microbial Fe(III) reduction processes were efficient and their rates varied significantly in different types of soils. Fe(III) reduction rates were 1.1-5.6 times as much in soils with glucose added as in those without glucose. Furthermore, Fe(III) reduction rates were similar in soils from the same parent materials, while they were highest in soils developed from sediments, with a mean rate of 1.87 mM per day when supplemented with glucose. In addition, the Fe(III) reduction rates, reaching 0.99 and 0.59 mM per day on average with and without glucose added, respectively, were higher in the paddy soils affected heavily by human activities than those in the forest soils (average rates of 0.38 and 0.15 mM per day when with and without glucose, respectively). All the soil weathering indices correlated linearly with Fe(III) reduction rates, even though the reduction of iron in soils with higher weathering degrees was partly inhibited by a higher soil protonation trend and fewer available iron reduction sites in the soils, which gives lower reduction rates. These results clearly illustrate that soil Fe(III) reduction rates are greatly dependent on soil geochemical properties and land-use types and help define which soil types exhibit similar degrees of Fe(III) reduction under field conditions.

  11. Characterization of two lactic acid bacteria and their influence on silage fermentation of napiergrass

    Directory of Open Access Journals (Sweden)

    Gang Guo, Xiao-hui Sun, Xiao-yan Qiu, Masataka Shimojo and Tao Shao

    2014-04-01

    Full Text Available Enterococcus faecium R5-1 (EF and Lactobacillus plantarum N30-6 (LP isolated from silages were identified and their influence on silage fermentation of napiergrass (Pennisetum purpureum Sch. harvested at various times of sunny day were studied. Strain LP had stronger growth ability, acid tolerating capacity and wider fermentable carbohydrates than strain EF. Napiergrass were cut at 0800, 1300 and 1800 h on a sunny day and were inoculated with strains EF and LP at 5 log cfu g-1. The concentrations of dry matter, water soluble carbohydrates and the ratio of lactic acid to acetic acid (LA/AA were higher (P<0.05 and ammonia-N (NH3-N, acetic acid concentrations and silage pH were lower (P<0.05 for uninoculated silages made of napiergrass cut at 1300 and 1800 h compared with cut at 0800 h. Silages inoculated with LP and EF had lower (P<0.05 NH3-N and acetic acid concentrations and higher (P<0.05 LA/AA than uninoculated silage made with napiergrass cut at 1300 and 1800 h. The EF-inoculated could not improve fermentation quality of silage made with napiergrass cut at 0800 h, which had higher (P<0.05 NH3-N and acetic acid concentrations than uninoculated silage. In conclusion, delayed cutting napiergrass at end of a sunny day was associated with better fermentation quality, and the silages inoculated with EF or LP could further improve fermentation quality.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. [Microbial air purity in hospitals. Operating theatres with air conditioning system].

    Science.gov (United States)

    Krogulski, Adam; Szczotko, Maciej

    2010-01-01

    The aim of this study was to show the influence of air conditioning control for microbial contamination of air inside the operating theatres equipped with correctly working air-conditioning system. This work was based on the results of bacteria and fungi concentration in hospital air obtained since 2001. Assays of microbial air purity conducted on atmospheric air in parallel with indoor air demonstrated that air filters applied in air-conditioning systems worked correctly in every case. To show the problem of fluctuation of bacteria concentration more precisely, every sequences of single results from successive measure series were examined independently.

  17. 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).

  18. Rhizosphere Bacteria

    Directory of Open Access Journals (Sweden)

    N.V. Feoktistova

    2016-06-01

    Full Text Available The review deals with the analysis of modern literature data on rhizosphere bacteria and their role in plant life. The structure of rhizosphere has been characterized. The role of plants as the centers of formation of microbial communities has been shown. Data on the main groups of microorganisms inhabiting the rhizosphere have been provided. The associative relationship between rhizobacteria and partner plants has been investigated. The modern concept of holobiont defined as the whole host plant organism and microorganisms associated with it has been reviewed. The role of rhizobacteria in the processes of nitrogen fixation has been discussed in detail. The mechanisms of direct stimulation of plant growth by biosynthesis of phytohormones, improvement of phosphorus and nitrogen nutrition, increase in resistance to stress, and stimulation mediated by antagonism against pathogenic microorganisms have been analyzed. The criteria for selection of rhizobacteria for practical purposes have been discussed.

  19. Soil carbon content and relative abundance of high affinity H2-oxidizing bacteria predict atmospheric H2 soil uptake activity better than soil microbial community composition

    NARCIS (Netherlands)

    Khdhiri, Mondher; Hesse, Laura; Popa, Maria Elena; Quiza, Liliana; Lalonde, Isabelle; Meredith, Laura K.; Röckmann, Thomas; Constant, Philippe

    2015-01-01

    Soil-atmosphere exchange of H2 is controlled by gas diffusion and the microbial production and oxidation activities in soil. Among these parameters, the H2 oxidation activity catalyzed by soil microorganisms harboring high affinity hydrogenase is the most difficult variable to parameterize because i

  20. 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

  1. Behavioral Microbiomics: A Multi-Dimensional Approach to Microbial Influence on Behavior

    OpenAIRE

    2015-01-01

    The role of microbes as a part of animal systems has historically been an under-appreciated aspect of animal life histories. Recently, evidence has emerged that microbes have wide-ranging influences on animal behaviour. Elucidating the complex relationships between host-microbe interactions and behaviour requires an expanded ecological perspective, involving the host, the microbiome and the environment; which, in combination, is termed the holobiont. We begin by seeking insights from the lite...

  2. 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.

  3. 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.

  4. 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

    OpenAIRE

    Karina Cenciani; Marcio Rodrigues Lambais; Carlos Clemente Cerri; Lucas Carvalho Basílio de Azevedo; Brigitte Josefine Feigl

    2009-01-01

    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 ...

  5. 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

  6. 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

  7. Influence of lactic acid bacteria on longevity of Caenorhabditis elegans and host defense against salmonella enterica serovar enteritidis.

    Science.gov (United States)

    Ikeda, Takanori; Yasui, Chikako; Hoshino, Kaori; Arikawa, Kentaro; Nishikawa, Yoshikazu

    2007-10-01

    This study aimed to develop a convenient model to investigate the senescence of host defenses and the influence of food and nutrition. A small soil nematode, Caenorhabditis elegans, was grown for 3 days from hatching on a lawn of Escherichia coli OP50 as the normal food source, and subsequently some of the nematodes were fed lactic acid bacteria (LAB). The life spans of worms fed LAB were significantly longer than the life spans of those fed OP50. To investigate the effect of age on host defenses, 3- to 7-day-old worms fed OP50 were transferred onto a lawn of Salmonella enterica serovar Enteritidis for infection. The nematodes died over the course of several days, and the accumulation of salmonella in the intestinal lumen suggested that the worms were infected. The 7-day-old worms showed a higher death rate during the 5 days after infection than nematodes infected at the age of 3 days; no clear difference was observed when the worms were exposed to OP50. We then investigated whether the LAB could exert probiotic effects on the worms' host defenses and improve life span. Seven-day-old nematodes fed LAB from the age of 3 days were more resistant to salmonella than worms fed OP50 until they were infected with salmonella. This study clearly showed that LAB can enhance the host defense of C. elegans and prolong life span. The nematode appears to be an appropriate model for screening useful probiotic strains or dietetic antiaging substances.

  8. 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.

  9. Factors influencing the survival and leaching of tetracycline-resistant bacteria and Escherichia coli through structured agricultural fields

    DEFF Research Database (Denmark)

    Bech, Tina Bundgaard; Rosenbom, Annette E.; Kjær, Jeanne;

    2014-01-01

    preferential transport through macropores, it was found that faecal bacteria were only leached to drainage water at Estrup. Here E. coli and tetracycline-resistant bacteria were detected at concentrations up to 3 CFU mL-1 and 130 CFU mL-1 respectively. A PCA plot revealed that leaching of faecal bacteria......Intense use of antibiotics in agricultural production may lead to the contamination of surface and groundwater by antibiotic-resistant bacteria. In the present study, the survival and leaching of E. coli and tetracycline-resistant bacteria were monitored at two well-structured agricultural fields....... Non-spiked pig slurry was injected in accordance with agricultural practice in the area. In both fields, the concentration of E. coli and tetracycline-resistant bacteria in the injected part of the plough layer decreased to the detection limit within 46–49 days. At Silstrup the decay was initiated...

  10. Influence of dietary recombinant microbial lipase on performance and quality characteristics of rainbow trout, Oncorhynchus mykiss

    DEFF Research Database (Denmark)

    Samuelsen, Troels; Isaksen, Mai; McLean, Ewen

    2001-01-01

    In order to assess whether supplementary lipase affected growth and body composition of trout, four diets were produced, consisting of (A) feed containing high (2083 mg kg(-1)), (B) low (208.3 mg kg(-1)) concentrations of lipase, (C) heat-treated (inactivated) lipase (2083 mg kg(-1)), and (D...... higher(P 0.05) on growth, fillet proximate composition, hepatosomatic, cardiac, or gut indices, and carcass percentage. However, lipase supplementation influenced the mono-unsaturated fatty acid profiles of the fillet (P

  11. Screening, Molecular Identification and Adaptability Exploration of Antarctic Microbial Flocculant-Producing Bacteria%南极微生物絮凝剂产生菌的筛选、分子鉴定及适应性研究

    Institute of Scientific and Technical Information of China (English)

    杜宁

    2012-01-01

    Seven microbial flocculant-producing bacteria were separated from antarctic seawater,sea ice and marine sediment. The molecular identification of these bacteria was by the way of 16S rRNA gene sequence amplification. Phylogenetic analysis showed that they belonged to Acinetobacter,Arthrobacter,Psychrobacter,Ser-ratia,Pseudomonas and Pseudoalteromonas, respectively. Different carbon sources and nitrogen sources were used to culture the bacteria in order to observe the change of flocculation activity. The bacteria, 1-2 and P2-13-1, were of universal adaptability to different carbon sources and nitrogen sources and had higher flocculation activity in economic culture medium.%从南极海水、海冰、底泥中分离得到7株产絮凝剂的菌株,通过16S rRNA基因序列扩增方法进行分子鉴定,分别隶属于不动杆菌属(Acinetobacter)、节杆菌属(Arthrobacter)、嗜冷杆菌属(Psychrobacter)、沙雷菌属(Serratia)、假单胞菌属(Pseudomonas)和假交替单胞菌属(Pseudoa lteromonas).改变培养基中碳源和氮源的组成并观察絮凝率的变化,筛选出在经济培养基条件下具有较高絮凝活性、同时对碳源和氮源具有普适性的菌株I-2和P2-13-1.

  12. 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。

  13. 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....

  14. 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...

  15. THE INFLUENCE OF KAPOK (Ceiba pentandra SEED OIL SUPPLEMENTATION ON CELLULOLYTIC ENZYME AND RUMEN MICROBIAL FERMENTATION ACTIVITY OF LOCAL SHEEP

    Directory of Open Access Journals (Sweden)

    W. Widiyanto

    2014-10-01

    Full Text Available This research was conducted to study the influence of kapok seed oil (KSO supplementation oncellulolytic enzyme and microbial fermentation activity. Sheep rumen fluid was used as enzyme sourceand inoculant, whereas carboxymethylcellulose (CMC was used as the substrate. There were 4 levels ofKSO supplementation as treatment, i.e. : 0% (T0, 5% (T1, 10% (T2, and 15% (T3. Two measuredvariables were reduced sugar production rate and gas fermentation production. The data were analyzedby analysis of variance in completely randomized design. The result showed that reduced sugarproduction rate in T0, T1, T2 and T3 treatment groups were 2.58; 2.93; 2.08 and 1.58 mg/gCMC/minute, respectively, whereas gas production were : 15.97; 13.26; 10.54 and 7.57 mg/g CMC,respectively. Kapok seed oil supplementation up to 5% DM of cellulose substrate (CMC did notinfluence the ruminal cellulolytic enzyme activity. The KSO supplementation level 10% - 15%decreased the ruminal cellulolytic enzyme activity.

  16. 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.

  17. Towards large-cohort comparative studies to define the factors influencing the gut microbial community structure of ASD patients

    Directory of Open Access Journals (Sweden)

    Daniel McDonald

    2015-03-01

    Full Text Available Differences in the gut microbiota have been reported between individuals with autism spectrum disorders (ASD and neurotypical controls, although direct evidence that changes in the microbiome contribute to causing ASD has been scarce to date. Here we summarize some considerations of experimental design that can help untangle causality in this complex system. In particular, large cross-sectional studies that can factor out important variables such as diet, prospective longitudinal studies that remove some of the influence of interpersonal variation in the microbiome (which is generally high, especially in children, and studies transferring microbial communities into germ-free mice may be especially useful. Controlling for the effects of technical variables, which have complicated efforts to combine existing studies, is critical when biological effect sizes are small. Large citizen-science studies with thousands of participants such as the American Gut Project have been effective at uncovering subtle microbiome effects in self-collected samples and with self-reported diet and behavior data, and may provide a useful complement to other types of traditionally funded and conducted studies in the case of ASD, especially in the hypothesis generation phase.

  18. 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.

  19. Soil microbial substrate properties and microbial community responses under irrigated organic and reduced-tillage crop and forage production systems.

    Science.gov (United States)

    Ghimire, Rajan; Norton, Jay B; Stahl, Peter D; Norton, Urszula

    2014-01-01

    Changes in soil microbiotic properties such as microbial biomass and community structure in response to alternative management systems are driven by microbial substrate quality and substrate utilization. We evaluated irrigated crop and forage production in two separate four-year experiments for differences in microbial substrate quality, microbial biomass and community structure, and microbial substrate utilization under conventional, organic, and reduced-tillage management systems. The six different management systems were imposed on fields previously under long-term, intensively tilled maize production. Soils under crop and forage production responded to conversion from monocropping to crop rotation, as well as to the three different management systems, but in different ways. Under crop production, four years of organic management resulted in the highest soil organic C (SOC) and microbial biomass concentrations, while under forage production, reduced-tillage management most effectively increased SOC and microbial biomass. There were significant increases in relative abundance of bacteria, fungi, and protozoa, with two- to 36-fold increases in biomarker phospholipid fatty acids (PLFAs). Under crop production, dissolved organic C (DOC) content was higher under organic management than under reduced-tillage and conventional management. Perennial legume crops and organic soil amendments in the organic crop rotation system apparently favored greater soil microbial substrate availability, as well as more microbial biomass compared with other management systems that had fewer legume crops in rotation and synthetic fertilizer applications. Among the forage production management systems with equivalent crop rotations, reduced-tillage management had higher microbial substrate availability and greater microbial biomass than other management systems. Combined crop rotation, tillage management, soil amendments, and legume crops in rotations considerably influenced soil

  20. 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

  1. 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%.

  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. Plant rhizosphere influence on microbial C metabolism: the role of elevated CO2, N availability and root stoichiometry

    Science.gov (United States)

    Microbial decomposer C metabolism is considered a factor controlling soil C stability, a key regulator of global climate. The plant rhizosphere is now recognized as a crucial driver of soil C dynamics but specific mechanisms are unclear. Climate change could affect microbial C metabolism via impacts...

  4. Effect of DNA extraction procedure, repeated extraction and ethidium monoazide (EMA)/propidium monoazide (PMA) treatment on overall DNA yield and impact on microbial fingerprints for bacteria, fungi and archaea in a reference soil.

    Science.gov (United States)

    Wagner, Andreas O; Praeg, Nadine; Reitschuler, Christoph; Illmer, Paul

    2015-09-01

    Different DNA extraction protocols were evaluated on a reference soil. A wide difference was found in the total extractable DNA as derived from different extraction protocols. Concerning the DNA yield phenol-chloroform-isomyl alcohol extraction resulted in high DNA yield but also in a remarkable co-extraction of contaminants making PCR from undiluted DNA extracts impossible. By comparison of two different extraction kits, the Macherey&Nagel SoilExtract II kit resulted in the highest DNA yields when buffer SL1 and the enhancer solution were applied. The enhancer solution not only significantly increased the DNA yield but also the amount of co-extracted contaminates, whereas additional disintegration strategies did not. Although a three times repeated DNA extraction increased the total amount of extracted DNA, microbial fingerprints were merely affected. However, with the 5th extraction this changed. A reduction of total DGGE band numbers was observed for archaea and fungi, whereas for bacteria the diversity increased. The application of ethidium monoazide (EMA) or propidium monoazide (PMA) treatment aiming on the selective removal of soil DNA derived from cells lacking cell wall integrity resulted in a significant reduction of total extracted DNA, however, the hypothesized effect on microbial fingerprints failed to appear indicating the need for further investigations.

  5. Microbial Biofilm Growth on Irradiated, Spent Nuclear Fuel Cladding

    Energy Technology Data Exchange (ETDEWEB)

    S.M. Frank

    2009-02-01

    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 × 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.

  6. Temporal dynamics of microbial communities in microcosms in response to pollutants.

    Science.gov (United States)

    Jiao, Shuo; Zhang, Zhengqing; Yang, Fan; Lin, Yanbing; Chen, Weimin; Wei, Gehong

    2017-02-01

    Elucidating the mechanisms underlying microbial succession is a major goal of microbial ecology research. Given the increasing human pressure on the environment and natural resources, responses to the repeated introduction of organic and inorganic pollutants are of particular interest. To investigate the temporal dynamics of microbial communities in response to pollutants, we analysed the microbial community structure in batch microcosms that were inoculated with soil bacteria following exposure to individual or combined pollutants (phenanthrene, n-octadecane, phenanthrene + n-octadecane and phenanthrene + n-octadecane + CdCl2 ). Subculturing was performed at 10-day intervals, followed by high-throughput sequencing of 16S rRNA genes. The dynamics of microbial communities in response to different pollutants alone and in combination displayed similar patterns during enrichment. Specifically, the repression and induction of microbial taxa were dominant, and the fluctuation was not significant. The rate of appearance for new taxa and the temporal turnover within microbial communities were higher than the rates reported in other studies of microbial communities in air, water and soil samples. In addition, conditionally rare taxa that were specific to the treatments exhibited higher betweenness centrality values in the co-occurrence network, indicating a strong influence on other interactions in the community. These results suggest that the repeated introduction of pollutants could accelerate microbial succession in microcosms, resulting in the rapid re-equilibration of microbial communities.

  7. Influence of chromium compounds on microbial growth and nucleic acid synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Toshihiko; Usui, Masauji; Yatome, Chizuko; Idaka, Eiichi (Gifu Univ., Gifu City (Japan))

    1989-08-01

    The wastewaters of the dyeing and the tanning industry contain often various chromium compounds, e.g. K{sub 2}Cr{sub 2}O{sub 7} and CrCl{sub 3}, with a large quantity of organic substances. Biological treatments have generally been employed in these industrial factories for the biodegradation of organic substances. The toxicity of the chromium compounds have been studied regarding mutagenicity and carcinogenicity from the medical view point. This is also of interest from the view point of wastewater biological treatments. The inhibitory effects of the compounds on the cell growth and the respiration in activated sludge have been reported in detail, but mechanisms have not been sufficiently elucidated. Therefore, the influence of K{sub 2}Cr{sub 2}O{sub 7} and CrCl{sub 3} on the cell growth and on the nucleic acid content was measured. Both compounds were the inhibitors of DNA synthesis. These action resulted in increased generation time a decrease in cell division. Chromium compounds and dyes coexist often in the wastewaters of the dyeing industries. The growth inhibitions of the mixed solution were measured.

  8. Functionality of microbial communities in constructed wetlands used for pesticide remediation: Influence of system design and sampling strategy.

    Science.gov (United States)

    Lv, Tao; Carvalho, Pedro N; Zhang, Liang; Zhang, Yang; Button, Mark; Arias, Carlos A; Weber, Kela P; Brix, Hans

    2017-03-01

    The objective of this study was to compare the microbial community metabolic function from both unsaturated and saturated constructed wetland mesocosms (CWs) when treating the pesticide tebuconazole. The comparison was performed for both interstitial water and substrate biofilm by community level physiological profiling (CLPP) via BIOLOG™ EcoPlates. For each CW design (saturated or unsaturated), six mesocosms were established including one unplanted and five planted individually with either Juncus effusus, Typha latifolia, Berula erecta, Phragmites australis or Iris pseudacorus. Microbial activity and metabolic richness of interstitial water from unsaturated CWs were significantly lower than that from saturated CWs. However, in general, the opposite result was observed for biofilm samples. Wetland plants promoted significantly higher biofilm microbial activity and metabolic richness than unplanted CWs in both CW designs. Differences in the microbial community functional profiles between plant species were only found for saturated CWs. Biofilm microbial metabolic richness was generally statistically higher than that of interstitial water in both unsaturated (1.4-24 times higher) and saturated (1.2-1.7 times higher) CWs. Carbon source (guild) utilization patterns were generally different between interstitial water and biofilm samples. Functionality of the biofilm microbial community was positively correlated to the removal of all pollutants (TN, NH4(+)-N, TP, TOC and tebuconazole) for both unsaturated and saturated CWs, suggesting the biofilm plays a more important role in pollutant removal than the interstitial water microbial community. Thus, merely observing the interstitial water microbial communities may underestimate the role of the microbial community in CW performance. Interestingly, the ability for the biofilm microbial community to utilize amino acids and amines/amides was positively correlated with tebuconazole removal in all system types.

  9. Dynamics of Heterocapsa sp. and the associated attached and free-living bacteria under the influence of dispersed and undispersed crude oil.

    Science.gov (United States)

    Severin, T; Bacosa, H P; Sato, A; Erdner, D L

    2016-12-01

    While many studies have examined the impact of oil on phytoplankton or bacteria, very few considered the effects on the biological complex formed by phytoplankton and their associated phytoplankton-attached (PA) and free-living (FL) bacteria. However, associated bacteria can affect the physiology of phytoplankton and influence their stress responses. In this study, we monitored the growth of Heterocapsa sp., an armoured dinoflagellate, exposed to crude oil, Corexit dispersant, or both. Growth of Heterocapsa sp. is unaffected by crude oil up to 25 ppm, a concentration similar to the lower range measured on Florida beaches after the Deepwater Horizon oil spill. The PA bacteria community was resistant to exposure, whereas the FL community shifted towards oil degraders; both responses could contribute to Heterocapsa sp. oil resistance. The growth rate of Heterocapsa sp. decreased significantly only when exposed to dispersed oil at 25 ppm, indicating a synergistic effect of dispersant on oil toxicity in this organism. For the first time, we demonstrated the decoupling of the responses of the PA and FL bacteria communities after exposure to an environmental stress, in this case oil and dispersant. Our findings suggest new directions to explore in the understanding of interactions between unicellular eukaryotes and prokaryotes.

  10. [Quantitative and qualitative analysis of total bacteria and ammonia-oxidizing bacteria in Buji River in wet season].

    Science.gov (United States)

    Sun, Hai-mei; Bai, Jiao-jiao; Sun, Wei-ling; Shao, Jun

    2012-08-01

    Microbial community structure and biomass in river water can reflect the situation of water quality in some extent. Nitrogen removal was mainly achieved by the nitrification and denitrification processes, and ammonia oxidation catalyzed by ammonia-oxidizing bacteria (AOB) is the first and rate-limiting step of nitrification. To explore the AOB community structure and biomass in nitrogen polluted river, water samples were collected from Buji River (Shenzhen) in wet season. Quantification of 16S rRNA copy numbers of total bacteria and AOB were performed by real-time PCR, and the microbial community structures were studied by denaturing gradient gel electrophoresis (DGGE). The results showed that the number of total bacterial 16S rRNA changed from 4.73 x 10(10) - 3.90 x 10(11) copies x L(-1) in the water samples. The copy numbers of AOB varied from 5.44 x 10(6) - 5.96 x 10(8)copies x L(-1). Redundancy discrimination analysis (RDA) showed that the main factors affecting the structure and the numbers of bacteria were different. For total bacteria, nitrate influenced the biomass significantly (P analysis showed that water pollution in downstream resulted in evident difference in microbial community structure between upstream and downstream water samples.

  11. 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.

  12. 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

    OpenAIRE

    Parro Víctor; Arcas Aida; Gómez Manuel J; Moreno-Paz Mercedes

    2010-01-01

    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. Th...

  13. Dynamics of Polyphosphate-Accumulating Bacteria in Wastewater Treatment Plant Microbial Communities Detected via DAPI (4′,6′-Diamidino-2-Phenylindole) and Tetracycline Labeling▿ †

    Science.gov (United States)

    Günther, S.; Trutnau, M.; Kleinsteuber, S.; Hause, G.; Bley, T.; Röske, I.; Harms, H.; Müller, S.

    2009-01-01

    Wastewater treatment plants with enhanced biological phosphorus removal represent a state-of-the-art technology. Nevertheless, the process of phosphate removal is prone to occasional failure. One reason is the lack of knowledge about the structure and function of the bacterial communities involved. Most of the bacteria are still not cultivable, and their functions during the wastewater treatment process are therefore unknown or subject of speculation. Here, flow cytometry was used to identify bacteria capable of polyphosphate accumulation within highly diverse communities. A novel fluorescent staining technique for the quantitative detection of polyphosphate granules on the cellular level was developed. It uses the bright green fluorescence of the antibiotic tetracycline when it complexes the divalent cations acting as a countercharge in polyphosphate granules. The dynamics of cellular DNA contents and cell sizes as growth indicators were determined in parallel to detect the most active polyphosphate-accumulating individuals/subcommunities and to determine their phylogenetic affiliation upon cell sorting. Phylotypes known as polyphosphate-accumulating organisms, such as a “Candidatus Accumulibacter”-like phylotype, were found, as well as members of the genera Pseudomonas and Tetrasphaera. The new method allows fast and convenient monitoring of the growth and polyphosphate accumulation dynamics of not-yet-cultivated bacteria in wastewater bacterial communities. PMID:19181836

  14. Dynamics of polyphosphate-accumulating bacteria in wastewater treatment plant microbial communities detected via DAPI (4',6'-diamidino-2-phenylindole) and tetracycline labeling.

    Science.gov (United States)

    Günther, S; Trutnau, M; Kleinsteuber, S; Hause, G; Bley, T; Röske, I; Harms, H; Müller, S

    2009-04-01

    Wastewater treatment plants with enhanced biological phosphorus removal represent a state-of-the-art technology. Nevertheless, the process of phosphate removal is prone to occasional failure. One reason is the lack of knowledge about the structure and function of the bacterial communities involved. Most of the bacteria are still not cultivable, and their functions during the wastewater treatment process are therefore unknown or subject of speculation. Here, flow cytometry was used to identify bacteria capable of polyphosphate accumulation within highly diverse communities. A novel fluorescent staining technique for the quantitative detection of polyphosphate granules on the cellular level was developed. It uses the bright green fluorescence of the antibiotic tetracycline when it complexes the divalent cations acting as a countercharge in polyphosphate granules. The dynamics of cellular DNA contents and cell sizes as growth indicators were determined in parallel to detect the most active polyphosphate-accumulating individuals/subcommunities and to determine their phylogenetic affiliation upon cell sorting. Phylotypes known as polyphosphate-accumulating organisms, such as a "Candidatus Accumulibacter"-like phylotype, were found, as well as members of the genera Pseudomonas and Tetrasphaera. The new method allows fast and convenient monitoring of the growth and polyphosphate accumulation dynamics of not-yet-cultivated bacteria in wastewater bacterial communities.

  15. Composition of bacteria harvested from the liquid and solid fractions of the rumen of sheep as influenced by feed intake.

    Science.gov (United States)

    Rodríguez, C A; González, J; Alvir, M R; Repetto, J L; Centeno, C; Lamrani, F

    2000-09-01

    A study was conducted to determine the effect of the feed intake on the chemical composition of bacteria associated with the solid (solid-associated bacteria; SAB) and liquid (liquid-associated bacteria; LAB) fractions of rumen digesta, the digestive passage kinetics and their relationships. Whole rumen contents were sampled after a period of continuous infusion of 15NH3 from four ruminally-cannulated wethers provided successively with a hay-concentrate diet (2 : 1 w/w on a DM basis) at two rates of feed intake: 40 and 80 g DM/kg body weight 0.75. SAB had a higher content of organic matter and total lipids (P bacteria and a decrease (P = 0.033) in their amino acid concentrations. Significant increases of rumen outflow rates of liquid and particles were also observed with increased feed intake. Rates of rumen outflow showed positive and negative linear relationships (P bacteria respectively. SAB contained significantly higher proportions of leucine, isoleucine, lysine and phenylalanine and lower proportions of alanine, methionine and valine than LAB. The increase in feed intake also induced significant changes in the amino acid profile of bacteria, increasing arginine and methionine and decreasing alanine and glycine proportions. Results show that the outflow rate of rumen contents is a major factor in determining the proportion of nucleic acids and protein in rumen bacteria and explains some of the differences observed between LAB and SAB.

  16. Comparison of the microbial communities of hot springs waters and the microbial biofilms in the acidic geothermal area of Copahue (Neuquén, Argentina).

    Science.gov (United States)

    Urbieta, María Sofía; González-Toril, Elena; Bazán, Ángeles Aguilera; Giaveno, María Alejandra; Donati, Edgardo

    2015-03-01

    Copahue is a natural geothermal field (Neuquén province, Argentina) dominated by the Copahue volcano. As a consequence of the sustained volcanic activity, Copahue presents many acidic pools, hot springs and solfataras with different temperature and pH conditions that influence their microbial diversity. The occurrence of microbial biofilms was observed on the surrounding rocks and the borders of the ponds, where water movements and thermal activity are less intense. Microbial biofilms are particular ecological niches within geothermal environments; they present different geochemical conditions from that found in the water of the ponds and hot springs which is reflected in different microbial community structure. The aim of this study is to compare microbial community diversity in the water of ponds and hot springs and in microbial biofilms in the Copahue geothermal field, with particular emphasis on Cyanobacteria and other photosynthetic species that have not been detected before in Copahue. In this study, we report the presence of Cyanobacteria, Chloroflexi and chloroplasts of eukaryotes in the microbial biofilms not detected in the water of the ponds. On the other hand, acidophilic bacteria, the predominant species in the water of moderate temperature ponds, are almost absent in the microbial biofilms in spite of having in some cases similar temperature conditions. Species affiliated with Sulfolobales in the Archaea domain are the predominant microorganism in high temperature ponds and were also detected in the microbial biofilms.

  17. Influence of water chlorination on the counting of bacteria with DAPI (4',6-diamidino-2-phenylindole).

    Science.gov (United States)

    Saby, S; Sibille, I; Mathieu, L; Paquin, J L; Block, J C

    1997-01-01

    Counting bacteria in drinking water samples by the epifluorescence technique after 4',6-diamidino-2-phenylindole (DAPI) staining is complicated by the fact that bacterial fluorescence varies with exposure of the cells to sodium hypochlorite. An Escherichia coli laboratory-grown suspension treated with sodium hypochlorite (5 to 15 mg of chlorine liter-1) for 90 min was highly fluorescent after DAPI staining probably due to cell membrane permeation and better and DAPI diffusion. At chlorine concentrations greater than 25 mg liter-1, DAPI-stained bacteria had only a low fluorescence. Stronger chlorine doses altered the DNA structure, preventing the DAPI from complexing with the DNA. When calf thymus DNA was exposed to sodium hypochlorite (from 15 to 50 mg of chlorine liter-1 for 90 min), the DNA lost the ability to complex with DAPI. Exposure to monochloramine did not have a similar effect. Treatment of drinking water with sodium hypochlorite (about 0.5 mg of chlorine liter-1) caused a significant increase in the percentage of poorly fluorescent bacteria, from 5% in unchlorinated waters (40 samples), to 35 to 39% in chlorinated waters (40 samples). The presence of the poorly fluorescent bacteria could explain the underestimation of the real number of bacteria after DAPI staining. Microscopic counting of both poorly and highly fluorescent bacteria is essential under these conditions to obtain the total number of bacteria. A similar effect of chlorination on acridine orange-stained bacteria was observed in treated drinking waters. The presence of the poorly fluorescent bacteria after DAPI staining could be interpreted as a sign of dead cells. PMID:9097452

  18. Results of microbial research of environment of international space station

    Science.gov (United States)

    Novikova, N.; Poddubko, S.; Deshevaya, E.; Polikarpov, N.; Rakova, N.

    Many years of exploitation of orbital space stations have moved forward ecological problems among which microbial society of the environment plays a most important role. Qualitative and quantitative characteristics of microorganisms in the environment of a space object can change considerably under the influence of conditions of space flight. In the process of exploitation of the International Space Station (ISS) microflora of air, interior surfaces and equipment is monitored on a regular basis to keep continuous assessment of sanitary and microbiological state of the environment. Up to the present time 32 species of microorganisms have been recovered in the ISS, namely 15species f bacteria and 17 species of moldy fungi. In the composition of microbial species mainly nonpathogenic species have been found. However, a number of bacteria discovered on the ISS, particularly some representatives of human microflora, are capable of causing different diseases when human immune system is compromised. Moreover, some bacteria and a considerable number of fungi are known to be potential biodestructors of construction materials, which leads to biodeterioration of construction materials and equipment. Results of our research show that the existing set of life-supporting systems can maintain microbial contamination within regulated levels. Furthermore, constant microbial monitoring of the environment is an integral part, which provides for the safety of space missions.

  19. Bacteria-Affinity 3D Macroporous Graphene/MWCNTs/Fe3O4 Foams for High-Performance Microbial Fuel Cells.

    Science.gov (United States)

    Song, Rong-Bin; Zhao, Cui-E; Jiang, Li-Ping; Abdel-Halim, Essam Sayed; Zhang, Jian-Rong; Zhu, Jun-Jie

    2016-06-29

    Promoting the performance of microbial fuel cells (MFCs) relies heavily on the structure design and composition tailoring of electrode materials. In this work, three-dimensional (3D) macroporous graphene foams incorporated with intercalated spacer of multiwalled carbon nanotubes (MWCNTs) and bacterial anchor of Fe3O4 nanospheres (named as G/MWCNTs/Fe3O4 foams) were first synthesized and used as anodes for Shewanella-inoculated microbial fuel cells (MFCs). Thanks to the macroporous structure of 3D graphene foams, the expanded electrode surface by MWCNTs spacing, as well as the high affinity of Fe3O4 nanospheres toward Shewanella oneidensis MR-1, the anode exhibited high bacterial loading capability. In addition to spacing graphene nanosheets for accommodating bacterial cells, MWCNTs paved a smoother way for electron transport in the electrode substrate of MFCs. Meanwhile, the embedded bioaffinity Fe3O4 nanospheres capable of preserving the bacterial metabolic activity provided guarantee for the long-term durability of the MFCs. With these merits, the constructed MFC possessed significantly higher power output and stronger stability than that with conventional graphite rod anode.

  20. In situ microbial filter used for bioremediation

    Science.gov (United States)

    Carman, M. Leslie; Taylor, Robert T.

    2000-01-01

    An improved method for in situ microbial filter bioremediation having increasingly operational longevity of an in situ microbial filter emplaced into an aquifer. A method for generating a microbial filter of sufficient catalytic density and thickness, which has increased replenishment interval, improved bacteria attachment and detachment characteristics and the endogenous stability under in situ conditions. A system for in situ field water remediation.

  1. 日粮中添加维基尼亚霉素对肉牛瘤胃微生物数量的影响%Influence of adding virginiamycin to diets of steers on ruminal microbial populations

    Institute of Scientific and Technical Information of China (English)

    郭同军; 王加启; 卜登攀; 王建平; 刘开朗; 李旦; 栾绍宇; 哈斯额尔敦

    2009-01-01

    This experiment was conducted to investigate the influence of adding virginiamycin to diets of steers on ruminal microbial populations. Four ruminally cannulated steers (559.4±30.1 kg) were utilized in a repeat crossover design. Treatment group added virginiamycin. Ruminal fluid was collected on 28 d of experimental period, starting at 8:00 prefeeding and at 12:00 and 16:00 post-feeding from the anterior, dorsal, and mid-ventral region of the rumen. The Amount of microbial was counted after culturing using roll-tube technique. We detected that adding virginiamycin to diets of steers could active suppression and regulate amylolytic bacteria populations and proteolytic bacteria populations (P<0.01). But the populations of cellulolytic bacteria, total viable bacteria and protozoon were no difference between control group and treatment group. Statistics result of virginiamycin regulated that the different sampling time showed: viginiamycin could inhibite and regulate amylolytic bacteria populations when the sampling time was at 8:00 (P<0.05). Viginiamycin could inhibite and regulate amylolytic bacteria populations and proteolytic bacteria populations when the sampling time was at 12: 00(P<0.05). But the populations of cellulolytic bacteria, total viable bacteria and protozoon were no difference between control group and treatment group at the different sampling time. But the populations of total viable bacteria and protozoon to showed a tendency that "high-low-high" with time changed between control group and treatment group. The results showed that virginiamycin could active suppression and regulate amylolytic bacteria populations and proteolytic bacteria populations on high concentration. Therefore, virginiamycin potentially could prevent ruminal acidosis.%选用4头体重为559.4±30.1 kg,健康且装有瘤胃瘘管的4岁龄杂交肉牛,进行重复交叉试验设计,处理组添加维吉尼亚霉素,旨在观察日粮中添加维基尼亚霉素对瘤胃微生物

  2. Investigation on the precaecal and faecal digestibility of lactulose and inulin and their influence on nutrient digestibility and microbial characteristics.

    Science.gov (United States)

    Branner, Gertraud R; Böhmer, Barbara M; Erhardt, W; Henke, Julia; Roth-Maier, Dora A

    2004-10-01

    This study was conducted to determine the pre-caecal and faecal digestibility of lactulose and inulin and the influence of these substances on nutrient digestibility and microbial characteristics. In metabolic trials three of six male growing pigs (German Landrace x Pietrain) were fitted with an ileo-rectal anastomosis (IRA) in end-to-end technique with preserved ileo-caeco-colic valve. The metabolic trials were conducted from day 21-63 after surgery. The remaining pigs were used as intact partners (IN) for the IRA pigs. The experimental diets, based on corn, wheat, barley and soybean meal, were supplemented with either 1.5% lactulose or 2% inulin in replacement of diatomaceous earth (control). Pre-caecal digestibility of lactulose and inulin was assessed to be 79 and 98%, respectively. faecal digestibility was determined as 100%. The supplementation of lactulose and inulin had only minor effects on the pre-caecal and faecal digestibility of nutrients. Significant differences in nutrient digestibility were obvious between IRA and IN pigs, whereas the IRA pigs showed lower digestibility values with the exception of ether extracts (EE). Bacterial population in the digesta of IRA and IN pigs were not affected by the experimental diets except the concentration of gram-negative anaerobes, which inclined when the IRA pigs received the lactulose diet. The pH of chyme was significantly lower than the pH of faeces, however the pH was unaffected by the different supplemented diets. The concentration of volatile fatty acids (VFA) in pre-caecal chyme decreased significantly when IRA pigs received the lactulose supplemented diet whereas VFA in faeces were unaffected by the supplementation. IRA pigs administered with lactulose excreted more N via the urine, but the nitrogen balance remained unaffected. From the present investigation it can be concluded that lactulose and inulin did only partly or scarcely fulfill the expectation of acting as prebiotics in pigs.

  3. Diazotrophic microbial mats

    NARCIS (Netherlands)

    Severin, I.; Stal, L.J.; Seckbach, J.; Oren, A.

    2010-01-01

    Microbial mats have been the focus of scientific research for a few decades. These small-scale ecosystems are examples of versatile benthic communities of microorganisms, usually dominated by phototrophic bacteria (e.g., Krumbein et al., 1977; Jørgensen et al., 1983). They develop as vertically stra

  4. Influence of Edaphic, Climatic, and Agronomic Factors on the Composition and Abundance of Nitrifying Microorganisms in the Rhizosphere of Commercial Olive Crops

    OpenAIRE

    Joan Caliz; Miguel Montes-Borrego; Xavier Triadó-Margarit; Madis Metsis; Landa, Blanca B.; Casamayor, Emilio O.

    2015-01-01

    The microbial ecology of the nitrogen cycle in agricultural soils is an issue of major interest. We hypothesized a major effect by farm management systems (mineral versus organic fertilizers) and a minor influence of soil texture and plant variety on the composition and abundance of microbial nitrifiers. We explored changes in composition (16S rRNA gene) of ammonia-oxidizing archaea (AOA), bacteria (AOB), and nitrite-oxidizing bacteria (NOB), and in abundance of AOA and AOB (qP...

  5. Progress in Research of Bacteria Fertilizer Strengthening Resistance of Plants

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Bacteria fertilizer is used most widely among all kinds of microbial fertilizers. We summarize the research headway of bacteria fertilizer. It mainly focuses on bacteria fertilizer improving the stress resistance of plant. Then we can offer basis to research and exploit bacteria fertilizer. These bacteria include azotobacter, photosynthetic bacteria, Bacillus mucilaginosus siliceous, phosphorus bacteria, plant growth-promoting rhizobacteria(PGPR), effective microorganism(EM).

  6. Nitrogen Additions and Microbial Biomass: A Global Meta-analysis

    Science.gov (United States)

    Treseder, K. K.

    2008-12-01

    Nitrogen (N) enrichment is an element of global change that could influence the growth and abundance of many organisms. In this meta-analysis, I synthesized responses of microbial biomass to N additions in 82 published field studies. I hypothesized that the biomass of fungi, bacteria, or the microbial community as a whole would be altered under N additions. I also predicted that changes in biomass would parallel changes in soil CO2 emissions. Microbial biomass declined 15% on average under N fertilization, but fungi and bacteria were not significantly altered in studies that examined each group separately. Moreover, declines in abundance of microbes and fungi were more evident in studies of longer durations and with higher total amounts of N added. In addition, responses of microbial biomass to N fertilization were significantly correlated with responses of soil CO2 emissions. There were no significant effects of biomes, fertilizer types, ambient N deposition rates, or methods of measuring biomass. Altogether, these results suggest that N enrichment could reduce microbial biomass in many ecosystems, with corresponding declines in soil CO2 emissions.

  7. Principal methods for isolation and identification of soil microbial communities.

    Science.gov (United States)

    Stefanis, Christos; Alexopoulos, Athanasios; Voidarou, Chrissa; Vavias, Stavros; Bezirtzoglou, Eugenia

    2013-01-01

    Soil microbial populations play crucial role in soil properties and influence below-ground ecosystem processes. Microbial composition and functioning changes the soil quality through decomposition of organic matter, recycling of nutrients, and biological control of parasites of plants. Moreover, the discovery that soil microbes may translate into benefits for biotechnology, management of agricultural, forest, and natural ecosystems, biodegradation of pollutants, and waste treatment systems maximized the need of scientists for the isolation and their characterization. Operations such as the production of antibiotics and enzymic activities from microorganisms of soil constitute objectives of industry in her effort to cope with the increase of population of earth and disturbance of environment and may ameliorate the effects of global climate change. In the past decades, new biochemical and molecular techniques have been developed in our effort to identify and classify soil bacteria. The goal of measuring the soil microbial diversity is difficult because of the limited knowledge about bacteria species and classification through families and orders. Molecular techniques extend our knowledge about microbial diversity and help the taxonomy of species. Measuring and monitoring soil microbial communities can lead us to better understanding of their composition and function in many ecosystem processes.

  8. Decline in Performance of Biochemical Reactors for Sulphate Removal from Mine-Influenced Water is Accompanied by Changes in Organic Matter Characteristics and Microbial Population Composition

    Directory of Open Access Journals (Sweden)

    Parissa Mirjafari

    2016-03-01

    Full Text Available Successful long-term bioremediation of mining-influenced water using complex organic matter and naturally-occurring microorganisms in sub-surface flow constructed wetlands requires a balance between easily and more slowly degrading material. This can be achieved by combining different types of organic materials. To provide guidance on what mixture combinations to use, information is needed on how the ratio of labile to recalcitrant components affects the degradation rate and the types of microbial populations supported. To investigate this, different ratios of wood and hay were used in up-flow column bioreactors treating selenium- and sulphate-containing synthetic mine-influenced water. The degradation rates of crude fibre components appeared to be similar regardless of the relative amounts of wood and hay. However, the nature of the degradation products might have differed in that those produced in the hay-rich bioreactors were more biodegradable and supported high sulphate-reduction rates. Microorganisms in the sulphate-reducing and cellulose-degrading inocula persisted in the bioreactors indicating that bio-augmentation was effective. There was a shift in microbial community composition over time suggesting that different microbial groups were involved in decomposition of more recalcitrant material. When dissolved organic carbon (DOC was over-supplied, the relative abundance of sulphate-reducers was low even through high sulphate-reduction rates were achieved. As DOC diminished, sulphate-reducers become more prevalent and their relative abundance correlated with sulphate concentrations rather than sulphate-reduction rate.

  9. The Influence of Micro-Oxygen Addition on Desulfurization Performance and Microbial Communities during Waste-Activated Sludge Digestion in a Rusty Scrap Iron-Loaded Anaerobic Digester

    Directory of Open Access Journals (Sweden)

    Renjun Ruan

    2017-02-01

    Full Text Available In this study, micro-oxygen was integrated into a rusty scrap iron (RSI-loaded anaerobic digester. Under an optimal RSI dosage of 20 g/L, increasing O2 levels were added stepwise in seven stages in a semi-continuous experiment. Results showed the average methane yield was 306 mL/g COD (chemical oxygen demand, and the hydrogen sulphide (H2S concentration was 1933 ppmv with RSI addition. O2 addition induced the microbial oxidation of sulphide by stimulating sulfur-oxidizing bacteria and chemical corrosion of iron, which promoted the generation of FeS and Fe2S3. In the 6th phase of the semi-continuous test, deep desulfurization was achieved without negatively impacting system performance. Average methane yield was 301.1 mL/g COD, and H2S concentration was 75 ppmv. Sulfur mass balance was described, with 84.0%, 11.90% and 0.21% of sulfur present in solid, liquid and gaseous phases, respectively. The Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE analysis revealed that RSI addition could enrich the diversity of hydrogenotrophic methanogens and iron-reducing bacteria to benefit methanogenesis and organic mineralization, and impoverish the methanotroph (Methylocella silvestris to reduce the consumption of methane. Micro-oxygen supplementation could enhance the diversity of iron-oxidizing bacteria arising from the improvement of Fe(II release rate and enrich the sulphur-oxidising bacteria to achieved desulfurization. These results demonstrated that RSI addition in combination with micro-oxygenation represents a promising method for simultaneously controlling biogas H2S concentration and improving digestion performance.

  10. Aminopeptidase activity by spoilage bacteria and its relationship to microbial load and sensory attributes of poultry legs during aerobic cold storage.

    Science.gov (United States)

    Guevara-Franco, José Alfredo; Alonso-Calleja, Carlos; Capita, Rosa

    2010-02-01

    The shelf life of poultry legs stored aerobically and the possible role of the aminopeptidase activity of gram-negative bacteria (p-nitroaniline test) as a predictor of poultry spoilage were evaluated on the basis of microbiological and sensory parameters. Chicken legs (n = 30) obtained immediately after evisceration in a local poultry processing plant were kept under aerobic refrigeration (4 +/- 1 degrees C) for 7 days. Microbiological (counts of aerobic bacteria and psychrotrophs) and sensory (odor, color, and general acceptability on a hedonic scale of 1 to 9) parameters and aminopeptidase activity (absorbance at 390 nm [A(390)]) determinations were performed after 0, 1, 3, 5, and 7 days of storage. Aerobic plate counts of 7 log CFU/g and a score of 6 for general acceptability were used as indicators of the end point of shelf life. Strong correlations (r > or = 0.76; P counts, hedonic scores, and A(390) values. Samples were judged as unacceptable (shelf-life end point) after 2 and 4 days on the basis of sensory and microbiological analyses, respectively. A(390) values of 0.52 and 0.89 (corresponding to p-nitroaniline concentrations of 6.25 and 10.7 microg/ml, respectively) are proposed as the upper limits for acceptability on the basis of sensory and microbiological determinations, respectively. However, these recommendations are based on a small set of samples, and their general application is yet to be verified.

  11. Pyrosequencing analysis of microbial community and food-borne bacteria on restaurant cutting boards collected in Seri Kembangan, Malaysia, and their correlation with grades of food premises.

    Science.gov (United States)

    Abdul-Mutalib, Noor-Azira; Amin Nordin, Syafinaz; Osman, Malina; Ishida, Natsumi; Tashiro, Kosuke; Sakai, Kenji; Tashiro, Yukihiro; Maeda, Toshinari; Shirai, Yoshihito

    2015-05-04

    This study adopts the pyrosequencing technique to identify bacteria present on 26 kitchen cutting boards collected from different grades of food premises around Seri Kembangan, a city in Malaysia. Pyrosequencing generated 452,401 of total reads of OTUs with an average of 1.4×10(7) bacterial cells/cm(2). Proteobacteria, Firmicutes and Bacteroides were identified as the most abundant phyla in the samples. Taxonomic richness was generally high with >1000 operational taxonomic units (OTUs) observed across all samples. The highest appearance frequencies (100%) were OTUs closely related to Enterobacter sp., Enterobacter aerogenes, Pseudomonas sp. and Pseudomonas putida. Several OTUs were identified most closely related to known food-borne pathogens, including Bacillus cereus, Cronobacter sakazaki, Cronobacter turisensis, Escherichia coli, E. coli O157:H7, Hafnia alvei, Kurthia gibsonii, Salmonella bongori, Salmonella enterica, Salmonella paratyphi, Salmonella tyhpi, Salmonella typhimurium and Yersinia enterocolitica ranging from 0.005% to 0.68% relative abundance. The condition and grade of the food premises on a three point cleanliness scale did not correlate with the bacterial abundance and type. Regardless of the status and grades, all food premises have the same likelihood to introduce food-borne bacteria from cutting boards to their foods and must always prioritize the correct food handling procedure in order to avoid unwanted outbreak of food-borne illnesses.

  12. Seasonal Development of Microbial Activity in Soils of Northern Norway

    Institute of Scientific and Technical Information of China (English)

    M. B(O)LTER; N. SOETHE; R. HORN; C. UHLIG

    2005-01-01

    Seasonal development of soil microbial activity and bacterial biomass in sub-polar regions was investigated to determine the impacts of biotic and abiotic factors, such as organic matter content, temperature and moisture. The study was performed during spring thaw from three cultivated meadows and two non-cultivated forest sites near Alta, in northern Norway. Samples from all five sites showed increasing respiration rates directly after the spring thaw with soil respiration activity best related to soil organic matter content. However, distributions of bacterial biomass showed fewer similarities to these two parameters. This could be explained by variations of litter exploitation through the biomass. Microbial activity started immediately after the thaw while root growth had a longer time lag. An influence of root development on soil microbes was proposed for sites where microorganisms and roots had a tight relationship caused by a more intensive root structure. Also a reduction of microbial activity due to soil compaction in the samples from a wheel track could not be observed under laboratory conditions. New methodological approaches of differential staining for live and dead organisms were applied in order to follow changes within the microbial community. Under laboratory conditions freeze and thaw cycles showed a damaging influence on parts of the soil bacteria. Additionally, different patterns for active vs.non-active bacteria were noticeable after freeze-thaw cycles.

  13. Performance and microbial ecology of air-cathode microbial fuel cells with layered electrode assemblies.

    Science.gov (United States)

    Butler, Caitlyn S; Nerenberg, Robert

    2010-05-01

    Microbial fuel cells (MFCs) can be built with layered electrode assemblies, where the anode, proton exchange membrane (PEM), and cathode are pressed into a single unit. We studied the performance and microbial community structure of MFCs with layered assemblies, addressing the effect of materials and oxygen crossover on the community structure. Four MFCs with layered assemblies were constructed using Nafion or Ultrex PEMs and a plain carbon cloth electrode or a cathode with an oxygen-resistant polytetrafluoroethylene diffusion layer. The MFC with Nafion PEM and cathode diffusion layer achieved the highest power density, 381 mW/m(2) (20 W/m(3)). The rates of oxygen diffusion from cathode to anode were three times higher in the MFCs with plain cathodes compared to those with diffusion-layer cathodes. Microsensor studies revealed little accumulation of oxygen within the anode cloth. However, the abundance of bacteria known to use oxygen as an electron acceptor, but not known to have exoelectrogenic activity, was greater in MFCs with plain cathodes. The MFCs with diffusion-layer cathodes had high abundance of exoelectrogenic bacteria within the genus Geobacter. This work suggests that cathode materials can significantly influence oxygen crossover and the relative abundance of exoelectrogenic bacteria on the anode, while PEM materials have little influence on anode community structure. Our results show that oxygen crossover can significantly decrease the performance of air-cathode MFCs with layered assemblies, and therefore limiting crossover may be of particular importance for these types of MFCs.

  14. Microbial community adaptation influences long-chain fatty acid conversion during anaerobic codigestion of fats, oils, and grease with municipal sludge.

    Science.gov (United States)

    Ziels, Ryan M; Karlsson, Anna; Beck, David A C; Ejlertsson, Jörgen; Yekta, Sepehr Shakeri; Bjorn, Annika; Stensel, H David; Svensson, Bo H

    2016-10-15

    Codigesting fats, oils, and greases with municipal wastewater sludge can greatly improve biomethane recovery at wastewater treatment facilities. Process loading rates of fats, oils, and greases have been previously tested with little knowledge of the digester microbial community structure, and high transient fat loadings have led to long chain fatty acid (LCFA) accumulation and digester upsets. This study utilized recently-developed quantitative PCR assays for syntrophic LCFA-degrading bacteria along with 16S amplicon sequencing to relate changes in microbial community structure to LCFA accumulation during transient loading increases to an anaerobic codigester receiving waste restaurant oil and municipal wastewater sludge. The 16S rRNA gene concentration of the syntrophic β-oxidizing genus Syntrophomonas increased to ∼15% of the Bacteria community in the codigester, but stayed below 3% in the control digester that was fed only wastewater sludge. Methanosaeta and Methanospirillum were the dominant methanogenic genera enriched in the codigester, and together comprised over 80% of the Archaea community by the end of the experimental period. Constrained ordination showed that changes in the codigester Bacteria and Archaea community structures were related to measures of digester performance. Notably, the effluent LCFA concentration in the codigester was positively correlated to the specific loading rate of waste oil normalized to the Syntrophomonas 16S rRNA concentration. Specific loading rates of 0-1.5 × 10(-12) g VS oil/16S gene copies-day resulted in LCFA concentrations below 30 mg/g TS, whereas LCFA accumulated up to 104 mg/g TS at higher transient loading rates. Based on the community-dependent loading limitations found, enhanced biomethane production from high loadings of fats, oils and greases can be achieved by promoting a higher biomass of slow-growing syntrophic consortia, such as with longer digester solids retention times. This work also

  15. Influence of rhizosphere microbial ecophysiological parameters from different plant species on butachlor degradation in a riparian soil.

    Science.gov (United States)

    Yang, Changming; Wang, Mengmeng; Li, Jianhua

    2012-01-01

    Biogeochemical processes in riparian zones regulate contaminant movement to receiving waters and often mitigate the impact of upland sources of contaminants on water quality. However, little research has been reported on the microbial process and degradation potential of herbicide in a riparian soil. Field sampling and incubation experiments were conducted to investigate differences in microbial parameters and butachlor degradation in the riparian soil from four plant communities in Chongming Island, China. The results suggested that the rhizosphere soil had significantly higher total organic C and water-soluble organic C relative to the nonrhizosphere soil. Differences in rhizosphere microbial community size and physiological parameters among vegetation types were significant. The rhizosphere soil from the mixed community of Phragmites australis and Acorus calamus had the highest microbial biomass and biochemical activity, followed by A. calamus, P. australis and Zizania aquatica. Microbial ATP, dehydrogenase activity (DHA), and basal soil respiration (BSR) in the rhizosphere of the mixed community of P. australis and A. calamus were 58, 72, and 62% higher, respectively, than in the pure P. australis community. Compared with the rhizosphere soil of the pure plant communities, the mixed community of P. australis and A. calamus displayed a significantly greater degradation rate of butachlor in the rhizosphere soil. Residual butachlor concentrations in rhizosphere soil of the mixed community of P. australis and A. calamus and were 48, 63, and 68% lower than three pure plant communities, respectively. Butachlor degradation rates were positively correlated to microbial ATP, DHA, and BSR, indicating that these microbial parameters may be useful in assessing butachlor degradation potential in the riparian soil.

  16. Influence of fluorescence of bacteria stained with acridine orange on the enumeration of microorganisms in raw milk.

    Science.gov (United States)

    Rapposch, S; Zangerl, P; Ginzinger, W

    2000-12-01

    The staining of gram-positive and gram-negative cultures with acridine orange in metabolically active and inactive states was investigated using a Bactoscan, direct epifluorescent filter technique (DEFT), and standard plate count as the reference method. The evaluation of the bacterial cultures in the Bactoscan revealed a linear relationship between Bactoscan counts (pulses) and the quantity of pure culture suspension used. But the proper detection of bacteria with the fluorescence optic methods was dependent on the type of microorganism and the physiological state of the cells. The Bactoscan and DEFT underestimated the bacterial counts of gram-negative cultures as compared with standard plate counting. When stained with acridine orange, metabolically active bacteria showed more orange fluorescence and a lower percentage of green fluorescent cells as compared with inactive bacteria. Bactoscan pulse height analysis (PHA) diagrams, graphs of the detected pulses and their intensity, showed low pulses of inactive bacteria. Many of these weak pulses were eliminated from counting because of their faint fluorescent staining. In contrast, PHA diagrams of metabolically active microorganisms showed bright staining and, therefore, high pulses. A complete count of these bacteria was possible. These investigations point out that discrepancies between the fluorescence optical counting methods and the standard plate count depend strongly on the staining of the cultures with acridine orange and, therefore, on the type of microorganism and the metabolic state of the cells measured.

  17. Influence of Co-Doping of Ni (II on Photocatalytic Activity of TiO2 for Pathogenic Bacteria Inhibition

    Directory of Open Access Journals (Sweden)

    Baharuddin Shaleh

    2010-04-01

    Full Text Available Nanoparticle titanium dioxide (TiO2 has most attention in the past decade, since it can be applied as alternative material on sterilization photocatalyst process. This research focused on increasing performance of titania such as structure, particles size and surface area through Ni ion doped on TiO2 surface by sol-gel technique. Product were used to design of a photobioreactor for sterilization process from pathogenic bacteria such as Escherichia coli, Staphylococcus aureus and Bacillus subtilis. Product were characterized using TG-DTA, XRD, TEM, SEM-EDS and BET. Titanium dioxide with anatase structure have 12.1 nm in particles size and surface area 49.6 m2/ g that have higher inhibition rate to bacteria cell. Photobiocatalytic reaction was carried out in various TiO2-Ni concentration and UV irradiation times. The anti bacteria from TiO2-Ni to all bacteria cell suspension after UV irradiated at λm : 365 nm has good synergistic effect. Effect of mechanical treatment by sonicator showed the increasing inhibition rate around 4% for 120 minute irradiation. Inhibition rate optimization for each bacteria gave different efficiency inhibition to TiO2-Ni concentration 1.5-2.0 g/L. TiO2-Ni inhibited growth of Escherichia coli, Staphylococcus aureus around ≥ 95% for 120 minute irradiation, while Bacillus subtilis resistance with inhibition percentage rate only 88.1%.

  18. Serpentine bacteria influence metal translocation and bioconcentration of Brassica juncea and Ricinus communis grown in multi-metal polluted soils.

    Science.gov (United States)

    Ma, Ying; Rajkumar, Mani; Rocha, Inês; Oliveira, Rui S; Freitas, Helena

    2014-01-01

    The aim of this study was to assess the effects of inoculation of rhizosphere or endophytic bacteria (Psychrobacter sp. SRS8 and Pseudomonas sp. A3R3, respectively) isolated from a serpentine environment on the plant growth and the translocation and accumulation of Ni, Zn, and Fe by Brassica juncea and Ricinus communis on a multi-metal polluted serpentine soil (SS). Field collected SS was diluted to 0, 25, 50, and 75% with pristine soil in order to obtain a range of heavy metal concentrations and used in microcosm experiments. Regardless of inoculation with bacteria, the biomass of both plant species decreased with increase of the proportion of SS. Inoculation of plants with bacteria significantly increased the plant biomass and the heavy metal accumulation compared with non-inoculated control in the presence of different proportion of SS, which was attributed to the production of plant growth promoting and/or metal mobilizing metabolites by bacteria. However, SRS8 showed a maximum increase in the biomass of the test plants grown even in the treatment of 75% SS. In turn, A3R3 showed maximum effects on the accumulation of heavy metals in both plants. Regardless of inoculation of bacteria and proportion of SS, both plant species exhibited low values of bioconcentration factor (communis in SS soils and have a great potential to be used as inoculants in phytostabilization scenarios of multi-metal contaminated soils.

  19. Caenorhabditis elegans responses to bacteria from its natural habitats

    Science.gov (United States)

    Rowedder, Holli; Braendle, Christian; Félix, Marie-Anne; Ruvkun, Gary

    2016-01-01

    Most Caenorhabditis elegans studies have used laboratory Escherichia coli as diet and microbial environment. Here we characterize bacteria of C. elegans' natural habitats of rotting fruits and vegetation to provide greater context for its physiological responses. By the use of 16S ribosomal DNA (rDNA)-based sequencing, we identified a large variety of bacteria in C. elegans habitats, with phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria being most abundant. From laboratory assays using isolated natural bacteria, C. elegans is able to forage on most bacteria (robust growth on ∼80% of >550 isolates), although ∼20% also impaired growth and arrested and/or stressed animals. Bacterial community composition can predict wild C. elegans population states in both rotting apples and reconstructed microbiomes: alpha-Proteobacteria-rich communities promote proliferation, whereas Bacteroidetes or pathogens correlate with nonproliferating dauers. Combinatorial mixtures of detrimental and beneficial bacteria indicate that bacterial influence is not simply nutritional. Together, these studies provide a foundation for interrogating how bacteria naturally influence C. elegans physiology. PMID:27317746

  20. Microbial and metabolic profiling reveal strong influence of water table and land-use patterns on classification of degraded tropical peatlands

    Science.gov (United States)

    Mishra, S.; Lee, W. A.; Hooijer, A.; Reuben, S.; Sudiana, I. M.; Idris, A.; Swarup, S.

    2014-04-01

    Tropical peatlands from southeast Asia are undergoing extensive drainage, deforestation and degradation for agriculture and human settlement purposes. This is resulting in biomass loss and subsidence of peat from its oxidation. Molecular profiling approaches were used to understand the relative influences of different land-use patterns, hydrological and physicochemical parameters on the state of degraded tropical peatlands. As microbial communities play a critical role in biogeochemical cascades in the functioning of peatlands, we used microbial and metabolic profiles as surrogates of community structure and functions, respectively. Profiles were generated from 230 bacterial 16 S rDNA fragments and 145 metabolic markers of 46 samples from 10 sites, including those from above and below water table in a contiguous area of 48 km2 covering five land-use types. These were degraded forest, degraded land, oil palm plantation, mixed crop plantation and settlements. Bacterial profiles were most influenced by variations in water table and land-use patterns, followed by age of drainage and peat thickness in that order. Bacterial profiling revealed differences in sites, based on the duration and frequency of water table fluctuations and on oxygen availability. Mixed crop plantations had the most diverse bacterial and metabolic profiles. Metabolic profiling, being closely associated with biogeochemical functions, could distinguish communities not only based on land-use types but also their geographic locations, thus providing a finer resolution than bacterial profiles. Agricultural inputs, such as nitrates, were highly associated with bacterial community structure of oil palm plantations, whereas phosphates and dissolved organic carbon influenced those from mixed crop plantations and settlements. Our results provide a basis for adopting molecular marker-based approaches to classify peatlands and determine relative importance of factors that influence peat functioning. Our

  1. Ni-P化学镀层表面黏液形成菌微生物污垢特性%Microbial fouling characteristics of slime-forming bacteria on the surface of electroless plating of Ni-P

    Institute of Scientific and Technical Information of China (English)

    武霖; 姚响

    2015-01-01

    A new experiment was designed to investigate microbial fouling characteristics on heat exchanger of electroless plating of Ni-P. In this paper,the surface of low-carbon steel sheet,which is common for heat exchanger,was modified by using the method of electroless Ni-P and low-carbon steels before and after electroless Ni-P,and pictures were taken by scanning electron microscopy. A comparative experiment was designed to investigate microbial fouling characteristics of low-carbon steel sheet and low-carbon steel sheet with electroless plating of Ni-P. Slime-forming bacteria that was isolated and purified from Songhua River is chosen as the strains. The changes of fouling were recorded by the method of weighing,and the changes of bacterial counts were recorded by the method of optical turbidity. The results of the experimental show that the surface morphology of electroless plating of Ni-P is better than that of low-carbon steel after the low-carbon steel sheet was electroless plated. For the corrosion caused by slime-forming bacteria,the corrosion resistance of electroless plating of Ni-P is better than that of low-carbon steel sheet and the anti-microbial fouling of electroless plating of Ni-P is preferred. When the slime-forming bacteria grew and reproduced vigorously and metabolites were excessive,biofouling was formed soon; in contrast,biofouling was formed slowly.%为了研究化学镀Ni-P换热器上黏液形成菌微生物污垢的特性,利用化学镀Ni-P的方式对低碳钢表面进行改性。采用微生物污垢对比实验,对低碳钢片和具有Ni-P镀层低碳钢片拍摄扫描电镜图,利用称重法记录污垢变化情况和光电比浊法记录黏液形成菌的数量变化情况。结果表明,Ni-P 镀层表面形貌明显好于低碳钢;Ni-P镀层相比于碳钢具有很好的耐蚀性和抗微生物污垢特性;黏液形成菌生长繁殖旺盛和细菌代谢产物多时,微生物污垢的形成就快。相反,微生物污垢形成就慢。

  2. 青贮乳酸菌的发酵生物量研究%Study of fermentation microbial amount of silage inoculant bacteria

    Institute of Scientific and Technical Information of China (English)

    李军训; 高洁; 王建华; 杜金华

    2004-01-01

    微生物青贮剂(Silage Inoculant Bacteria),亦称青贮接种菌、生物青贮剂、青贮饲料发酵剂,是专门用于饲料青贮的一类微生物添加剂,由1种或1种以上乳酸菌、酶和一些营养体组成,主要作用是有目的地调节青贮料内微生物区系,调控青贮发酵过程,促进乳酸菌大量繁殖更快地产生乳酸,促进多糖与粗纤维的转化,从而有效地提高青贮饲料的质量。

  3. Microbial eukaryotic distributions and diversity patterns in a deep-sea methane seep ecosystem.

    Science.gov (United States)

    Pasulka, Alexis L; Levin, Lisa A; Steele, Josh A; Case, David H; Landry, Michael R; Orphan, Victoria J

    2016-09-01

    Although chemosynthetic ecosystems are known to support diverse assemblages of microorganisms, the ecological and environmental factors that structure microbial eukaryotes (heterotrophic protists and fungi) are poorly characterized. In this study, we examined the geographic, geochemical and ecological factors that influence microbial eukaryotic composition and distribution patterns within Hydrate Ridge, a methane seep ecosystem off the coast of Oregon using a combination of high-throughput 18S rRNA tag sequencing, terminal restriction fragment length polymorphism fingerprinting, and cloning and sequencing of full-length 18S rRNA genes. Microbial eukaryotic composition and diversity varied as a function of substrate (carbonate versus sediment), activity (low activity versus active seep sites), sulfide concentration, and region (North versus South Hydrate Ridge). Sulfide concentration was correlated with changes in microbial eukaryotic composition and richness. This work also revealed the influence of oxygen content in the overlying water column and water depth on microbial eukaryotic composition and diversity, and identified distinct patterns from those previously observed for bacteria, archaea and macrofauna in methane seep ecosystems. Characterizing the structure of microbial eukaryotic communities in response to environmental variability is a key step towards understanding if and how microbial eukaryotes influence seep ecosystem structure and function.

  4. Impact of chromium-contaminated wastewaters on the microbial community of a river.

    Science.gov (United States)

    Branco, Rita; Chung, Ana-Paula; Veríssimo, António; Morais, Paula V

    2005-09-01

    The influence of chromium on the microbial community structure was analyzed in a river system subjected to long-term chromium contamination, by plating and by sequencing 16S rRNA genes cloned from DNA extracted from the river sediments. We also analyzed the influence of chromium on the ability of the microbial community to resist and reduce Cr(VI) and on its resistance to antibiotics. Shifts in the microbial community structure were analyzed by amplified ribosomal DNA restriction analysis fingerprinting. The isolates obtained were phylogenetically related to Actinobacteria, Firmicutes, Bacteroidetes and Proteobacteria, whereas Acidobacteria and Deltaproteobacteria were only revealed by clone analyses. Cr(VI)-resistant and Cr(VI)-reducing strains were isolated in all sites examined. However, each sample site had a microbial community with a different antibiotic resistance pattern. Our study seems to indicate that in this river ecosystem chromium influenced the microbial communities, altering some of their functional characteristics, such as the percentage of the microbial community able to resist or to reduce Cr(VI) and the phylogenetic groups isolated, but it did not affect the structural diversity. Furthermore, the concentration of Cr(VI) in the sediments could not be correlated with a lower number of bacteria or lower index of generic diversity, neither with the ability of the microbial community to resist or to reduce higher Cr(VI) concentrations.

  5. Serpentine bacteria influence metal translocation and bioconcentration of Brassica juncea and Ricinus communis grown in multi-metal polluted soils

    Directory of Open Access Journals (Sweden)

    Ying eMa

    2015-01-01

    Full Text Available The aim of this study was to assess the effects of inoculation of rhizosphere or endophytic bacteria (Psychrobacter sp. SRS8 and Pseudomonas sp. A3R3, respectively isolated from a serpentine environment on the plant growth and the translocation and accumulation of Ni, Zn and Fe by Brassica juncea and Ricinus communis on a multi-metal polluted serpentine soil (SS. Field collected SS was diluted to 0, 25, 50 and 75% with pristine soil in order to obtain a range of heavy metal concentrations and used in microcosm experiments. Regardless of inoculation with bacteria, the biomass of both plant species decreased with increase of the proportion of SS. Inoculation of plants with bacteria significantly increased the plant biomass and the heavy metal accumulation compared with non-inoculated control in the presence of different proportion of SS, which was attributed to the production of plant growth promoting and/or metal mobilizing metabolites by bacteria. However, SRS8 showed a maximum increase in the biomass of the test plants grown even in the treatment of 75% SS. In turn, A3R3 showed maximum effects on the accumulation of heavy metals in both plants. Regardless of inoculation of bacteria and proportion of SS, both plant species exhibited low values of bioconcentration factor (<1 for Ni and Fe. The inoculation of both bacterial strains significantly increased the translocation factor (TF of Ni while decreasing the TF of Zn in both plant species. Besides this contrasting effect, the TFs of all metals were < 1, indicating that all studied bacteria-plant combinations are suitable for phytostabilization. This study demonstrates that the bacterial isolates A3R3 and SRS8 improved the growth of B. juncea and R. communis in SS soils and have a great potential to be used as inoculants in phytostabilization scenarios of multi-metal contaminated soils.

  6. Influence of detachment procedure and diet on recovery of solid-associated bacteria from sheep ruminal digesta and representativeness of bacterial isolates as assessed by automated ribosomal intergenic spacer analysis-polymerase chain reaction.

    Science.gov (United States)

    Ramos, S; Tejido, M L; Ranilla, M J; Martínez, M E; Saro, C; Carro, M D

    2009-11-01

    only a moderate similarity between the bacterial communities attached to digesta and those recovered in the bacterial pellets was obtained. Values of duodenal microbial flow estimated using SAB as reference bacteria were greater with FRE compared with STO and MET, but all DP detected similar differences between diets, and therefore did not influence the interpretation of results.

  7. Evolutionary relationships of wild hominids recapitulated by gut microbial communities.

    Directory of Open Access Journals (Sweden)

    Howard Ochman

    Full Text Available Multiple factors over the lifetime of an individual, including diet, geography, and physiologic state, will influence the microbial communities within the primate gut. To determine the source of variation in the composition of the microbiota within and among species, we investigated the distal gut microbial communities harbored by great apes, as present in fecal samples recovered within their native ranges. We found that the branching order of host-species phylogenies based on the composition of these microbial communities is completely congruent with the known relationships of the hosts. Although the gut is initially and continuously seeded by bacteria that are acquired from external sources, we establish that over evolutionary timescales, the composition of the gut microbiota among great ape species is phylogenetically conserved and has diverged in a manner consistent with vertical inheritance.

  8. Orchid-associated bacteria produce indole-3-acetic acid, promote seed germination, and increase their microbial yield in response to exogenous auxin.

    Science.gov (United States)

    Tsavkelova, Elena A; Cherdyntseva, Tatiana A; Klimova, Svetlana Yu; Shestakov, Andrey I; Botina, Svetlana G; Netrusov, Alexander I

    2007-12-01

    Germination of orchid seeds is a complex process. In this paper we focus on interactions between the host-plant and its bacterial partners via indole-3-acetic acid (IAA). Originally isolated from the roots of the epiphytic orchid Dendrobium moschatum, the strains of Rhizobium, Microbacterium, Sphingomonas, and Mycobacterium genera were among the most active IAA producers. Addition of exogenous tryptophan significantly enhanced auxin formation both in mineral and complex media. The presence of IAA and indole-3-acetaldehyde was confirmed by HPLC. Indole-3-pyruvic and indole-3-lactic acids were also detected in supernatants of culture filtrates of Sphingomonas sp., Rhizobium sp., and Microbacterium sp., while indole-3-acetamide was identified only in Mycobacterium sp. Some concentration- and strain-dependent effects of exogenous IAA on bacterial development were also established. Treatment of the cultures with 10 and 100 microg/ml of auxin resulted in an increase in microbial yield. None of the investigated strains was able to utilize IAA as a source of carbon and energy. Furthermore, inoculation of D. moschatum seeds with Sphingomonas sp. and Mycobacterium sp. resulted in considerable enhancement of orchid seeds germination. This growth-promoting activity was observed in the absence of any plant growth stimulators or mycorrhizal fungi, usually required for orchid germination.

  9. Development and optimization of microbial fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Davila, D.; Vigues, N.; Sanchez, O.; Garrido, L.; Tomas, N.; Mas, J. [Univ. Autonoma de Barcelona, Barcelona (Spain). Dept. de Genetica y Microbiologia; Esquivel, J.P.; Sabate, N.; Del Campo, F.J.; Munoz, F.J. [Inst. de Microelectronica de Barcelona-CNM (CSIC), Barcelona (Spain)

    2008-04-15

    While global energy demand increases daily, fossil fuel sources are being depleted at an unsustainable pace. Fuel cells represent a solution as they are more efficient than other energy sources. A microbial fuel cell is an electrochemical device capable of continuously converting chemical energy into electrical energy for as long as adequate fuel and oxidant are available. A microbial fuel cell (MFC) adds the benefit of converting chemical energy from organic compounds, such as simple carbohydrates or organic waste matter, into electricity by using bacteria as biocatalysts. This article described the effect of several parameters that affect the operation of a microbial fuel cell (MFC). The study is based on a methodology utilized in previous studies which employed escherichia coli as biocatalyst and neutral red as the electron mediator in a mediated electron transfer (MET) microbial fuel cell. The study analysed the influence of the bacterial concentration, the effective area of electrode and the volume of the cell. It was concluded that there is a proportional energy production to the bacterial concentration present in the anode compartment. It was demonstrated that an increase in the volume of the cell negatively affects the power produced by the cells. 8 refs., 1 tab., 5 figs.

  10. Influence of soil management practices and substrate availability on microbial biomass and its activities in some haplic luvisols

    Energy Technology Data Exchange (ETDEWEB)

    Friedel, Jurgen K. [University Hohenheeim, Stuttgart (Germany)

    1996-07-01

    Soil microbial biomass and activities are sensitive indicators of management effects. Higher contents of microbial biomass and higher activities, for example, are found with crop rotations in contrast to bare fallow and mono culture systems. The main reason for these differences is a higher input of crop and root residues in crop rotation systems, leading to more microbial available substrate. The objectives of this study were to describe indices for microbial available substrate in arable soils depending on management practices, and to relate them with soil microbial biomass and activities. At two locations (Muttergarten and hinger Hof near the University of Hohenheim, Stuttgart, SW-Germany), adenosine triphosphate (ATP) contents and microbial activities were measured in haplic Luviosls. As indices for microbial available substrate, water soluble organic carbon compounds in soils were determined and decomposable young soil organic matter was calculated from organic fertilizers and crop and root residues using empirical decomposition functions. Higher ATP contents and microbial activities were observed along with organic fertilization (liquid cattle manure) than with mineral fertilization. Shallow cultivation with a rotary cultivator led to higher values of microbial properties in the upper part of the Ap horizon than ploughing. Soil microbial parameters were higher in plots under a rape-cereals crop rotation, compared to a legumes-cereals crop rotation. Microbial biomass and its activities were related more closely to decomposable young soil organic matter than to soil humus content or to any other soil property. Water soluble organic carbon compounds did not prove as an indicator of microbial available substrate. [Spanish] La biomasa y la actividad microbianas son indicadores sensibles de los efectos del manejo del suelo. Por ejemplo, con la rotacion de cultivos se obtiene un contenido y una actividad mayores de la biomasa microbiana en contraste con el simple

  11. Advances in microbial insect control in horticultural ecosystems

    Science.gov (United States)

    The use of microbial organisms as biological control agents has progressed significantly since Metschnikoff launched the first attempt at microbial insect control with Metarhizium anisopliae in 1879. Following the lead of Metschnikoff, entomopathogenic nematodes, fungi, bacteria and viruses have b...

  12. Molecular and chemical dialogues in bacteria-protozoa interactions

    NARCIS (Netherlands)

    Song, C.; Mazzola, M.; Cheng, X.; Oetjen, J.; Alexandrov, T.; Dorrestein, P.; Watrous, J.; Voort, van der M.; Raaijmakers, J.M.

    2015-01-01

    Protozoan predation of bacteria can significantly affect soil microbial community composition and ecosystem functioning. Bacteria possess diverse defense strategies to resist or evade protozoan predation. For soil-dwelling Pseudomonas species, several secondary metabolites were proposed to provide p

  13. Genomics of oral bacteria.

    Science.gov (United States)

    Duncan, Margaret J

    2003-01-01

    Advances in bacterial genetics came with the discovery of the genetic code, followed by the development of recombinant DNA technologies. Now the field is undergoing a new revolution because of investigators' ability to sequence and assemble complete bacterial genomes. Over 200 genome projects have been completed or are in progress, and the oral microbiology research community has benefited through projects for oral bacteria and their non-oral-pathogen relatives. This review describes features of several oral bacterial genomes, and emphasizes the themes of species relationships, comparative genomics, and lateral gene transfer. Genomics is having a broad impact on basic research in microbial pathogenesis, and will lead to new approaches in clinical research and therapeutics. The oral microbiota is a unique community especially suited for new challenges to sequence the metagenomes of microbial consortia, and the genomes of uncultivable bacteria.

  14. Exopolysaccharides from Marine Bacteria

    Institute of Scientific and Technical Information of China (English)

    CHI Zhenming; FANG Yan

    2005-01-01

    Microbial polysaccharides represent a class of important products of growing interest for many sectors of industry. In recent years, there has been a growing interest in isolating new exopolysaccharides (EPSs)-producing bacteria from marine environments, particularly from various extreme marine environments. Many new marine microbial EPSs with novel chemical compositions, properties and structures have been found to have potential applications in fields such as adhesives,textiles, pharmaceuticals and medicine for anti-cancer, food additives, oil recovery and metal removal in mining and industrial waste treatments, etc This paper gives a brief summary of the information about the EPSs produced by marine bacteria,including their chemical compositions, properties and structures, together with their potential applications in industry.

  15. 近红外光源对光合细菌生长的影响%Influence of near-infrared on growth of photosynthetic bacteria

    Institute of Scientific and Technical Information of China (English)

    李家洲; 张冬青; 黄荣林; 赵鑫; 肖玉平

    2012-01-01

    光合细菌的光合色素能吸收近红外光进行光合作用.利用加可见光滤光镜的卤钨灯作为近红外光源,照射光合细菌,探讨其对光合细菌生长的影响.结果表明,相对于可见光,近红外光对光合细菌的生长有明显促进作用,可使最大菌体浓度提高45%以上.近红外光照强度饱和区为20W~35W之间,低于20W时,光合细菌的生长速率随光照强度升高而升高;超过50W后,近红外光对光合细菌产生抑制作用.温度和pH值2个培养参数对近红外光的光照效果没有明显的影响.%The photosynthetic pigments can absorb near-infrared lights for photosynthesis. Halogen tungsten lamp filtered with visible-light filter lens as light source, influence of photosynthetic bacteria growth was researched. The results were as follows: compared with visible-light, near-infrared lights can promote photosynthetic bacteria growth markedly and can increase the max cell concentration about 45%; the region of near-infrared light saturation was between 20W to 35W; when lower than 20W, growth rate of photosynthetic bacteria increased with light intensity increasing; when higher than 50W, near-infrared light could inhibit photosynthetic bacteria growth. The temperature and pH value had no influence on the near-infrared light effect.

  16. Influence of water hardness on the ability of water to rinse bacteria from the skin of processed broilers

    Science.gov (United States)

    Experiments were conducted to examine the effect of water hardness on the ability of water to rinse bacteria from the skin of processed broiler chickens. Very hard water (200 ppm total hardness) was prepared by dissolving 0.38 g calcium chloride (CaCl2) and 0.175 g magnesium chloride hexahydrate (Mg...

  17. INFLUENCE OF ORGANIC NUTRIENTS AND COCULTURES ON THE COMPETITIVE BEHAVIOR OF 1,2-DICHLOROETHANE-DEGRADING BACTERIA

    NARCIS (Netherlands)

    Wijngaard, Arjan J. van den; Kleij, Roelof G. van der; Doornweerd, Rianne E.; Janssen, Dick B.

    1993-01-01

    The effects of organic nutrients and cocultures on substrate removal by and competitive behavior of 1,2-dichloroethane-degrading bacteria were investigated. Xanthobacter autotrophicus GJ10 needed biotin for optimal growth on 1,2-dichloroethane. In continuous culture, dilution of biotin to a concentr

  18. Influence of Dilution Rate on Enzymes of Intermediary Metabolism in Two Freshwater Bacteria Grown in Continuous Culture

    NARCIS (Netherlands)

    Matin, A.; Grootjans, A.; Hogenhuis, H.

    1976-01-01

    Two freshwater bacteria, a Pseudomonas sp. and a Spirillum sp., were grown in continuous culture under steady-state conditions in L-lactate-, succinate-, ammonium- or phosphate-limited media. In Pseudomonas sp., NAD-independent and NAD-dependent L-lactate dehydrogenases, aconitase, isocitrate dehydr

  19. Microbiologically Influenced Corrosion: an Update

    Science.gov (United States)

    2014-01-01

    the material that failed was carbon steel and the electrolyte were saline waters, but the microorgan- isms, the environments and the corrosion...different salinities . Martin et al.42 demonstrated that Ecorr ennoblement was site specific, varying 100 mV versus SCE between locations, with higher...microbial consortium of the fungus Aspergillus niger and bacteria influenced the corrosion–inhibiting effectiveness of Crz6 leached from chromate (CrO{24

  20. Migration of bacteria in compacted clay-based material

    Energy Technology Data Exchange (ETDEWEB)

    Stroes-Gascoyne, S.; Lucht, L.M.; Oscarson, D.W.; Dixon, D.A.; Hume, H.B.; Miller, S.H

    1997-11-01

    Buffer (a mixture of 50 wt.% Na-bentonite and 50 wt.% silica sand compacted to a dry density of about 1.68 g/cm{sup 3}) would surround waste containers in a Canadian nuclear fuel waste disposal vault. The initial heat and radiation output from these containers would likely prevent significant microbial activity at or near container surfaces for some time after disposal, thereby limiting effects such as microbially-influenced corrosion. Microbial repopulation of buffer as conditions improve with time may not occur because of its small pores. Experiments with irradiated buffer plugs (2.2 cm in diameter and 5-cm long; at dry densities of 1.68 and 1.80 g/cm{sup 3}) were performed to assess the ability of microbes to migrate in buffer. Viable bacteria (Pseudomonas stutzeri), in a suitable growth medium, were brought in contact with one end of the plugs. After 2, 4, 8, 16 and 20 weeks, the plugs were sectioned and tested for moisture content and viable bacteria. Results showed that the plugs were slowly wetting and that moisture levels were sufficient to sustain microbes. No evidence of P. stutzeri was found, however, in all but the first 0.5 cm of the plugs (smallest distance sampled) over a 20-week period. The results suggest that microbial migration in buffer is limited or even completely prevented because of its relatively small pores. (author)

  1. IN-VITRO EFFECTS OF HERBICIDES ON SOIL MICROBIAL COMMUNITIES

    Directory of Open Access Journals (Sweden)

    AABID HUSSAIN LONE

    2014-03-01

    Full Text Available Effect of six different herbicides representing four chemical families on soil microbial communities was studied using laboratory microcosm approach. The herbicides tested were isoproturon, metribuzin, clodinafop propargyl, atlantis (Mesosulfuron methyl 3% + Idosulfuron Methyl Sodium 0.6% WG and sulfosulfuron applied at normal agricultural rates, and UPH-110 (Clodinafop propargyl 12% + Metribuzin 42% WG tested at four different application rates. Microbial response to the applied herbicides was studied following cultivation dependent approach. The microbial community showed a mixed response towards applied herbicides. With a few exceptions, metribuzin displayed a negative, clodinafop a positive and sulphonylurea herbicides a neutral effect while as the effect of isoproturon was variable. Significant toxic impact of UPH-110 was mostly observed at higher concentrations (@ 600 and 1000 g ha-1. The magnitude of hazard and duration of toxicity increased as the dose of UPH-110 increased. The influence whether positive or negative, was only transitory in nature and recovered to the level of untreated microcosms by or before 30th day of application. Among the microbial groups studied, fungal population was least affected at field rate, bacteria, actinomycetes and Azotobacter showed mixed response while as the phosphorus solubilizers population showed a tendency to increase in response to the applied herbicides.The herbicidal impact on soil microbial population was found to depend on the nature and dose of herbicide used and also the type of microbial group

  2. Characterization of N-acyl homoserine lactones (AHLs) producing bacteria isolated from vacuum-packaged refrigerated turbot (Scophthalmus maximus) and possible influence of exogenous AHLs on bacterial phenotype.

    Science.gov (United States)

    Zhang, Caili; Zhu, Suqin; Jatt, Abdul-Nabi; Zeng, Mingyong

    2016-01-01

    Quorum sensing (QS) is a cell-to-cell communication mechanism through which microbial cells communicate and regulate their wide variety of biological activities. N-acyl homoserine lactones (AHLs) are considered to be the most important QS signaling molecules produced by several Gram-negative bacteria. The present study aimed to screen the AHLs-producing bacteria from spoiled vacuum-packaged refrigerated turbot (Scophthalmus maximus) by biosensor assays, and the profiles of AHLs produced by these bacteria were determined using reversed-phase thin-layer chromatography (RP-TLC) and gas chromatography-mass spectrometry (GC-MS). Effects of exogenous AHLs and QS inhibitor (QSI) on the phenotypes (i.e., extracellular proteolytic activity and biofilm formation) of the AHLs-producing bacteria were also evaluated. Our results demonstrated that eight out of twenty-two isolates were found to produce AHLs. Three of the AHLs-producing isolates were identified as Serratia sp., and the other five were found to belong to the family of Aeromonas. Two isolates (i.e., S. liquefaciens A2 and A. sobria B1) with higher AHLs-producing activities were selected for further studies. Mainly, RP-TLC and GC-MS analysis revealed three AHLs, i.e., 3-oxo-C6-HSL, C8-HSL and C10-HSL were produced by S. liquefaciens A2, while five AHLs, i.e., C4-HSL, C6-HSL, C8-HSL, C10-HSL, and C12-HSL, were produced by A. sobria B1. Moreover, production of AHLs in both bacterial strains were found to be density-dependent, and the AHLs activity reached a maximum level in their middle logarithmic phase and decreased in the stationary phase. The addition of exogenous AHLs and QSI decreased the specific protease activity both of the Serratia A2 and Aeromonas B1. Exogenous AHLs inhibited the biofilm formation of Serratia A2 while it enhanced the biofilm formation in Aeromonas B1. QSI inhibited the specific protease activity and biofilm formation in both bacterial strains.

  3. Microbial utilization of the industrial wastewater pollutants 2-ethylhexylthioglycolic acid and iso-octylthioglycolic acid by aerobic gram-negative bacteria.

    Science.gov (United States)

    Toups, Mario; Wübbeler, Jan Hendrik; Steinbüchel, Alexander

    2010-04-01

    Industrial wastewater from the production of sulfur containing esters and the resulting products of this synthesis, 2-ethylhexylthioglycolic acid (EHTG) and iso-octylthioglycolic acid (IOTG), were deployed in this study to enrich novel bacterial strains, since no wastewater and EHTG or IOTG degrading microorganisms were hitherto described or available. In addition, nothing is known about the biodegradation of these thiochemicals. The effect of this specific wastewater on the growth behaviour of microorganisms was investigated using three well-known Gram-negative bacteria (Escherichia coli, Pseudomonas putida, and Ralstonia eutropha). Concentrations of 5% (v/v) wastewater in complex media completely inhibited growth of these three bacterial strains. Six bacterial strains were successfully isolated, characterized and identified by sequencing their 16S rRNA genes. Two isolates referred to as Achromobacter sp. strain MT-E3 and Pseudomonas sp. strain MT-I1 used EHTG or IOTG, respectively, as well as the wastewater as sole source of carbon and energy for weak growth. More notably, both isolates removed these sulfur containing esters in remarkable amounts from the cultures supernatant. One further isolate was referred to as Klebsiella sp. strain 58 and exhibited an unusual high tolerance against the wastewater's toxicity without utilizing the contaminative compounds. If cultivated with gluconic acid as additional carbon source, the strain grew even in presence of more than 40% (v/v) wastewater. Three other isolates belonging to the genera Bordetella and Pseudomonas tolerated these organic sulfur compounds but showed no degradation abilities.

  4. Microbial ecology on the microcosm level: Activity and population dynamics of methanotrophic bacteria during early succession in a flooded rice field soil

    Science.gov (United States)

    Krause, S.; Frenzel, P.

    2009-04-01

    Methane oxidizing bacteria (methanotrophs) play an important role in natural wetlands and rice fields preventing large amounts of methane from escaping into the atmosphere. The occurrence of both type I and type II methanotrophs in the soil surface layer has been demonstrated in many studies. However, there is no profound understanding which of them are responsible for the oxidizing activity and how they differ ecologically. Hence, a gradient microcosm system was applied simulating oxic-anoxic interfaces of water saturated soils to unravel population dynamics in early succession of methanotrophs in a flooded rice paddy. Additionally, environmental parameters were analyzed to link environment, populations, and their specific activity. We measured pmoA-based (particulate methane monooxygenase) terminal restriction fragment length polymorphism (T-RFLP) profiles both on transcription and population level. DNA T-RFLP patterns showed no major differences in the methanotrophic community structure remaining relatively constant over time. In contrast the active methanotrophic community structure as detected by pmoA mRNA T-RFLP analysis clearly demonstrated a distinct pattern from DNA T-RFLP profiles. While type II represented the most prominent group on the population level it seems to play a minor role on the transcription level. Furthermore there were no clear implications towards a link between soil parameters (e.g. NH4+ concentration) and methanotrophic community structure.

  5. Impact of warm winters on microbial growth

    Science.gov (United States)

    Birgander, Johanna; Rousk, Johannes; Axel Olsson, Pål

    2014-05-01

    Growth of soil bacteria has an asymmetrical response to higher temperature with a gradual increase with increasing temperatures until an optimum after which a steep decline occurs. In laboratory studies it has been shown that by exposing a soil bacterial community to a temperature above the community's optimum temperature for two months, the bacterial community grows warm-adapted, and the optimum temperature of bacterial growth shifts towards higher temperatures. This result suggests a change in the intrinsic temperature dependence of bacterial growth, as temperature influenced the bacterial growth even though all other factors were kept constant. An intrinsic temperature dependence could be explained by either a change in the bacterial community composition, exchanging less tolerant bacteria towards more tolerant ones, or it could be due to adaptation within the bacteria present. No matter what the shift in temperature tolerance is due to, the shift could have ecosystem scale implications, as winters in northern Europe are getting warmer. To address the question of how microbes and plants are affected by warmer winters, a winter-warming experiment was established in a South Swedish grassland. Results suggest a positive response in microbial