WorldWideScience

Sample records for microbially mediated processes

  1. Microbially mediated mineral carbonation

    Science.gov (United States)

    Power, I. M.; Wilson, S. A.; Dipple, G. M.; Southam, G.

    2010-12-01

    Mineral carbonation involves silicate dissolution and carbonate precipitation, which are both natural processes that microorganisms are able to mediate in near surface environments (Ferris et al., 1994; Eq. 1). (Ca,Mg)SiO3 + 2H2CO3 + H2O → (Ca,Mg)CO3 + H2O + H4SiO4 + O2 (1) Cyanobacteria are photoautotrophs with cell surface characteristics and metabolic processes involving inorganic carbon that can induce carbonate precipitation. This occurs partly by concentrating cations within their net-negative cell envelope and through the alkalinization of their microenvironment (Thompson & Ferris, 1990). Regions with mafic and ultramafic bedrock, such as near Atlin, British Columbia, Canada, represent the best potential sources of feedstocks for mineral carbonation. The hydromagnesite playas near Atlin are a natural biogeochemical model for the carbonation of magnesium silicate minerals (Power et al., 2009). Field-based studies at Atlin and corroborating laboratory experiments demonstrate the ability of a microbial consortium dominated by filamentous cyanobacteria to induce the precipitation of carbonate minerals. Phototrophic microbes, such as cyanobacteria, have been proposed as a means for producing biodiesel and other value added products because of their efficiency as solar collectors and low requirement for valuable, cultivable land in comparison to crops (Dismukes et al., 2008). Carbonate precipitation and biomass production could be facilitated using specifically designed ponds to collect waters rich in dissolved cations (e.g., Mg2+ and Ca2+), which would allow for evapoconcentration and provide an appropriate environment for growth of cyanobacteria. Microbially mediated carbonate precipitation does not require large quantities of energy or chemicals needed for industrial systems that have been proposed for rapid carbon capture and storage via mineral carbonation (e.g., Lackner et al., 1995). Therefore, this biogeochemical approach may represent a readily

  2. Disentangling mechanisms that mediate the balance between stochastic and deterministic processes in microbial succession

    NARCIS (Netherlands)

    Dini-Andreote, Francisco; Stegen, James C.; van Elsas, Jan Dirk; Salles, Joana Falcao

    2015-01-01

    Ecological succession and the balance between stochastic and deterministic processes are two major themes within microbial ecology, but these conceptual domains have mostly developed independent of each other. Here we provide a framework that integrates shifts in community assembly processes with

  3. Disentangling mechanisms that mediate the balance between stochastic and deterministic processes in microbial succession.

    Science.gov (United States)

    Dini-Andreote, Francisco; Stegen, James C; van Elsas, Jan Dirk; Salles, Joana Falcão

    2015-03-17

    Ecological succession and the balance between stochastic and deterministic processes are two major themes within microbial ecology, but these conceptual domains have mostly developed independent of each other. Here we provide a framework that integrates shifts in community assembly processes with microbial primary succession to better understand mechanisms governing the stochastic/deterministic balance. Synthesizing previous work, we devised a conceptual model that links ecosystem development to alternative hypotheses related to shifts in ecological assembly processes. Conceptual model hypotheses were tested by coupling spatiotemporal data on soil bacterial communities with environmental conditions in a salt marsh chronosequence spanning 105 years of succession. Analyses within successional stages showed community composition to be initially governed by stochasticity, but as succession proceeded, there was a progressive increase in deterministic selection correlated with increasing sodium concentration. Analyses of community turnover among successional stages--which provide a larger spatiotemporal scale relative to within stage analyses--revealed that changes in the concentration of soil organic matter were the main predictor of the type and relative influence of determinism. Taken together, these results suggest scale-dependency in the mechanisms underlying selection. To better understand mechanisms governing these patterns, we developed an ecological simulation model that revealed how changes in selective environments cause shifts in the stochastic/deterministic balance. Finally, we propose an extended--and experimentally testable--conceptual model integrating ecological assembly processes with primary and secondary succession. This framework provides a priori hypotheses for future experiments, thereby facilitating a systematic approach to understand assembly and succession in microbial communities across ecosystems.

  4. Targeted quantification of functional enzyme dynamics in environmental samples for microbially mediated biogeochemical processes: Targeted quantification of functional enzyme dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Li, Minjing [School of Environmental Studies, China University of Geosciences, Wuhan 430074 People' s Republic of China; Gao, Yuqian [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Qian, Wei-Jun [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Shi, Liang [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Liu, Yuanyuan [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Nelson, William C. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Nicora, Carrie D. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Resch, Charles T. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Thompson, Christopher [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Yan, Sen [School of Environmental Studies, China University of Geosciences, Wuhan 430074 People' s Republic of China; Fredrickson, James K. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Zachara, John M. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Liu, Chongxuan [Pacific Northwest National Laboratory, Richland, WA 99354 USA; School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055 People' s Republic of China

    2017-07-13

    Microbially mediated biogeochemical processes are catalyzed by enzymes that control the transformation of carbon, nitrogen, and other elements in environment. The dynamic linkage between enzymes and biogeochemical species transformation has, however, rarely been investigated because of the lack of analytical approaches to efficiently and reliably quantify enzymes and their dynamics in soils and sediments. Herein, we developed a signature peptide-based technique for sensitively quantifying dissimilatory and assimilatory enzymes using nitrate-reducing enzymes in a hyporheic zone sediment as an example. Moreover, the measured changes in enzyme concentration were found to correlate with the nitrate reduction rate in a way different from that inferred from biogeochemical models based on biomass or functional genes as surrogates for functional enzymes. This phenomenon has important implications for understanding and modeling the dynamics of microbial community functions and biogeochemical processes in environments. Our results also demonstrate the importance of enzyme quantification for the identification and interrogation of those biogeochemical processes with low metabolite concentrations as a result of faster enzyme-catalyzed consumption of metabolites than their production. The dynamic enzyme behaviors provide a basis for the development of enzyme-based models to describe the relationship between the microbial community and biogeochemical processes.

  5. Deep subsurface microbial processes

    Science.gov (United States)

    Lovley, D.R.; Chapelle, F.H.

    1995-01-01

    Information on the microbiology of the deep subsurface is necessary in order to understand the factors controlling the rate and extent of the microbially catalyzed redox reactions that influence the geophysical properties of these environments. Furthermore, there is an increasing threat that deep aquifers, an important drinking water resource, may be contaminated by man's activities, and there is a need to predict the extent to which microbial activity may remediate such contamination. Metabolically active microorganisms can be recovered from a diversity of deep subsurface environments. The available evidence suggests that these microorganisms are responsible for catalyzing the oxidation of organic matter coupled to a variety of electron acceptors just as microorganisms do in surface sediments, but at much slower rates. The technical difficulties in aseptically sampling deep subsurface sediments and the fact that microbial processes in laboratory incubations of deep subsurface material often do not mimic in situ processes frequently necessitate that microbial activity in the deep subsurface be inferred through nonmicrobiological analyses of ground water. These approaches include measurements of dissolved H2, which can predict the predominant microbially catalyzed redox reactions in aquifers, as well as geochemical and groundwater flow modeling, which can be used to estimate the rates of microbial processes. Microorganisms recovered from the deep subsurface have the potential to affect the fate of toxic organics and inorganic contaminants in groundwater. Microbial activity also greatly influences 1 the chemistry of many pristine groundwaters and contributes to such phenomena as porosity development in carbonate aquifers, accumulation of undesirably high concentrations of dissolved iron, and production of methane and hydrogen sulfide. Although the last decade has seen a dramatic increase in interest in deep subsurface microbiology, in comparison with the study of

  6. Chlorine stress mediates microbial surface attachment in drinking water systems.

    Science.gov (United States)

    Liu, Li; Le, Yang; Jin, Juliang; Zhou, Yuliang; Chen, Guowei

    2015-03-01

    Microbial attachment to drinking water pipe surfaces facilitates pathogen survival and deteriorates disinfection performance, directly threatening the safety of drinking water. Notwithstanding that the formation of biofilm has been studied for decades, the underlying mechanisms for the origins of microbial surface attachment in biofilm development in drinking water pipelines remain largely elusive. We combined experimental and mathematical methods to investigate the role of environmental stress-mediated cell motility on microbial surface attachment in chlorination-stressed drinking water distribution systems. Results show that at low levels of disinfectant (0.0-1.0 mg/L), the presence of chlorine promotes initiation of microbial surface attachment, while higher amounts of disinfectant (>1.0 mg/L) inhibit microbial attachment. The proposed mathematical model further demonstrates that chlorination stress (0.0-5.0 mg/L)-mediated microbial cell motility regulates the frequency of cell-wall collision and thereby controls initial microbial surface attachment. The results reveal that transport processes and decay patterns of chlorine in drinking water pipelines regulate microbial cell motility and, thus, control initial surface cell attachment. It provides a mechanistic understanding of microbial attachment shaped by environmental disinfection stress and leads to new insights into microbial safety protocols in water distribution systems.

  7. Acid-deposition research program. Volume 2. Effects of acid-forming emissions on soil microorganisms and microbially-mediated processes

    Energy Technology Data Exchange (ETDEWEB)

    Visser, S.; Danielson, R.M.; Parr, J.F.

    1987-02-01

    The interactions of soil physical, chemical, and biological processes are ultimately expressed in a soil's fertility and its capacity for plant production. Consequently, much of the research conducted to date regarding the impact of acid-forming pollutants on soil properties has been geared towards possible effects on plant productivity. This trend continues in this paper where the effects of acidic deposition on microbial communities are reviewed in relation to potential impact on plant growth. The objectives of the review are to discuss: (1) The effects of acid-forming emissions (primarily S-containing pollutants) on microbial community structure with emphasis on qualitative and quantitative aspects; (2) The effects of acidic deposition on microbially mediated processes (i.e., community functions); (3) Acidification effects of pollutants on symbiotic and disease-causing microorganisms. The symbionts discussed include ectomycorrhizal fungi, vesicular-arbuscular mycorrhizal fungi, and N/sub 2/-fixing bacteria, particularly Rhizobium, while the disease-causing microorganisms will include those responsible for foliage, stem, and root diseases.

  8. Two-year microbial adaptation during hydrogen-mediated biogas upgrading process in a serial reactor configuration

    DEFF Research Database (Denmark)

    Treu, Laura; Kougias, Panagiotis; de Diego-Díaz, B.

    2018-01-01

    Microbial dynamics in an upgrading biogas reactor system undergoing a more than two years-period at stable operating conditions were explored. The carbon dioxide generated during biomass degradation in the first reactor of the system was converted to methane into the secondary reactor by addition...... of external hydrogen. Considering the overall efficiency, the long-term operation period resulted in an improved biogas upgrading performance (99% methane content). However, a remarkable accumulation of acetate was revealed, indicating the enhancement of homoacetogenic activity. For this reason, a shift...

  9. Microbially mediated barite dissolution in anoxic brines

    International Nuclear Information System (INIS)

    Ouyang, Bingjie; Akob, Denise M.; Dunlap, Darren; Renock, Devon

    2017-01-01

    Fluids injected into shale formations during hydraulic fracturing of black shale return with extraordinarily high total-dissolved-solids (TDS) and high concentrations of barium (Ba) and radium (Ra). Barite, BaSO_4, has been implicated as a possible source of Ba as well as a problematic mineral scale that forms on internal well surfaces, often in close association with radiobarite, (Ba,Ra)SO_4. The dissolution of barite by abiotic processes is well quantified. However, the identification of microbial communities in flowback and produced water necessitates the need to understand barite dissolution in the presence of bacteria. Therefore, we evaluated the rates and mechanisms of abiotic and microbially-mediated barite dissolution under anoxic and hypersaline conditions in the laboratory. Barite dissolution experiments were conducted with bacterial enrichment cultures established from produced water from Marcellus Shale wells located in northcentral Pennsylvania. These cultures were dominated by anaerobic halophilic bacteria from the genus Halanaerobium. Dissolved Ba was determined by ICP-OES and barite surfaces were investigated by SEM and AFM. Our results reveal that: 1) higher amounts of barium (up to ∼5 × ) are released from barite in the presence of Halanaerobium cultures compared to brine controls after 30 days of reaction, 2) etch pits that develop on the barite (001) surface in the presence of Halanaerobium exhibit a morphology that is distinct from those that form during control experiments without bacteria, 3) etch pits that develop in the presence of Halanaerobium exhibit a morphology that is similar to the morphology of etch pits formed in the presence of strong organic chelators, EDTA and DTPA, and 4) experiments using dialysis membranes to separate barite from bacteria suggest that direct contact between the two is not required in order to promote dissolution. These results suggest that Halanaerobium increase the rate of barite dissolution in anoxic

  10. Microbial exopolysaccharide-mediated synthesis and stabilization of metal nanoparticles.

    Science.gov (United States)

    Sathiyanarayanan, Ganesan; Dineshkumar, Krishnamoorthy; Yang, Yung-Hun

    2017-11-01

    Exopolysaccharides (EPSs) are structurally and functionally valuable biopolymer secreted by different prokaryotic and eukaryotic microorganisms in response to biotic/abiotic stresses and to survive in extreme environments. Microbial EPSs are fascinating in various industrial sectors due to their excellent material properties and less toxic, highly biodegradable, and biocompatible nature. Recently, microbial EPSs have been used as a potential template for the rapid synthesis of metallic nanoparticles and EPS-mediated metal reduction processes are emerging as simple, harmless, and environmentally benign green chemistry approaches. EPS-mediated synthesis of metal nanoparticles is a distinctive metabolism-independent bio-reduction process due to the formation of interfaces between metal cations and the polyanionic functional groups (i.e. hydroxyl, carboxyl and amino groups) of the EPS. In addition, the range of physicochemical features which facilitates the EPS as an efficient stabilizing or capping agents to protect the primary structure of the metal nanoparticles with an encapsulation film in order to separate the nanoparticle core from the mixture of composites. The EPS-capping also enables the further modification of metal nanoparticles with expected material properties for multifarious applications. The present review discusses the microbial EPS-mediated green synthesis/stabilization of metal nanoparticles, possible mechanisms involved in EPS-mediated metal reduction, and application prospects of EPS-based metal nanoparticles.

  11. Humic substances-mediated microbial reductive dehalogenation of triclosan

    Science.gov (United States)

    Wang, L.; Xu, S.; Yang, Y.

    2015-12-01

    The role of natural organic matter in regulating the redox reactions as an electron shuttle has received lots of attention, because it can significantly affect the environmental degradation of contaminants and biogeochemical cycles of major elements. However, up to date, limited studies examined the role of natural organic matter in affecting the microbial dehalogenation of emergent organohalides, a critical detoxification process. In this study, we investigated the humic substance (HS)-mediated microbial dehalogenation of triclosan, a widely used antimicrobial agent. We found that the presence of HS stimulated the microbial degradation of triclosan by Shewanella putrefaciens CN-32. In the absence of HS, the triclosan was degraded gradually, achieving 8.6% residual at 8 days. With HS, the residual triclosan was below 2% after 4 days. Cl- was confirmed by ion chromatography analysis, but the dehalogenation processes and other byproducts warrant further investigations. The impact of HS on the degradation of triclosan was highly dependent on the concentration of HS. When the HS was below 15 mg/L, the degradation rate constant for triclosan increased with the organic carbon concentration. Beyond that point, the increased organic carbon concentration decreased the degradation of triclosan. Microbially pre-reduced HS abiotically reduced triclosan, testifying the electron shuttling processes. These results indicate that dissolved organic matter plays a dual role in regulating the degradation of triclosan: it mediates electron transport and inhibits the bioavailability through complexation. Such novel organic matter-mediated reactions for organohalides are important for evaluating the natural attenuation of emergent contaminants and designing cost-effective engineering treatment.

  12. Analysis of multiparty mediation processes

    NARCIS (Netherlands)

    Vuković, Siniša

    2013-01-01

    Crucial challenges for multiparty mediation processes include the achievement of adequate cooperation among the mediators and consequent coordination of their activities in the mediation process. Existing literature goes only as far as to make it clear that successful mediation requires necessary

  13. Microbial contamination associated with the processing of ...

    African Journals Online (AJOL)

    Anihouvi Gildas

    2013-05-01

    May 1, 2013 ... tchachanga investigated, but different processing methods had significant changes in the microbial ... placed on wooden skewers and cooked on the embers of charcoal .... processing place, including the use of dirty jute bags,.

  14. Microbial processes in coastal pollution

    International Nuclear Information System (INIS)

    Capone, D.G.; Bauer, J.E.

    1992-01-01

    In this chapter, the authors describe the nature and range of some of the interactions that can occur between the microbiota and environmental contaminants in coastal areas. The implications of such interactions are also discussed. Pollutant types include inorganic nutrients, heavy metals, bulk organics, organic contaminants, pathogenic microorganisms and microbial pollutants. Both the effects of pollutants such as petroleum hydrocarbons on natural microbial populations and the mitigation of contaminant effects by complexation and biodegradation are considered. Finally, several areas of emerging concerns are presented that involve a confluence of biogeochemistry, microbial ecology and applied and public health microbiology. These concerns range in relevance from local/regional to oceanic/global scales. 308 ref

  15. Microbial stratification and microbially catalyzed processes along a hypersaline chemocline

    Science.gov (United States)

    Hyde, A.; Joye, S. B.; Teske, A.

    2017-12-01

    Orca Basin is the largest deep hypersaline anoxic basin in the world, covering over 400 km2. Located at the bottom of the Gulf of Mexico, this body of water reaches depths of 200 meters and is 8 times denser (and more saline) than the overlying seawater. The sharp pycnocline prevents any significant vertical mixing and serves as a particle trap for sinking organic matter. These rapid changes in salinity, oxygen, organic matter, and other geochemical parameters present unique conditions for the microbial communities present. We collected samples in 10m intervals throughout the chemocline. After filtering the water, we used high-throughput bacterial and archaeal 16S rRNA gene sequencing to characterize the changing microbial community along the Orca Basin chemocline. The results reveal a dominance of microbial taxa whose biogeochemical function is entirely unknown. We then used metagenomic sequencing and reconstructed genomes for select samples, revealing the potential dominant metabolic processes in the Orca Basin chemocline. Understanding how these unique geochemical conditions shape microbial communities and metabolic capabilities will have implications for the ocean's biogeochemical cycles and the consequences of expanding oxygen minimum zones.

  16. Microbial ecology of bacterially mediated PCB biodegradation

    International Nuclear Information System (INIS)

    Pettigrew, C.A. Jr.

    1989-01-01

    The roles of plasmid mediated and consortia mediated polychlorinated biphenyl (PCB) biodegradation by bacterial populations isolated from PCB contaminated freshwater sediments were investigated. PCB degrading bacteria were isolated by DNA:DNA colony hybridization, batch enrichments, and chemostat enrichment. Analysis of substrate removal and metabolite production were done using chlorinated biphenyl spray plates, reverse phase high pressure liquid chromatography, Cl - detection, and 14 C-labeled substrate mineralization methods. A bacterial consortium, designated LPS10, involved in a concerted metabolic attack on chlorinated biphenyls, was shown to mineralize 4-chlorobiphenyl (4CB) and 4,4'-dichlorobiphenyl (4,4' CB). The LPS10 consortium was isolated by both batch and chemostat enrichment using 4CB and biphenyl (BP) as sole carbon source and was found to have tree bacterial isolates that predominated; these included: Pseudomonas, testosteroni LPS10A which mediated the breakdown of 4CB and 4,4' CB to the putative meta-cleavage product and subsequently to 4-chlorobenzoic acid (4CBA), an isolate tentatively identified as an Arthrobacter sp. LPS10B which mediated 4CBA degradation, and Pseudomonas putida by A LPS10C whose role in the consortium has not been determined

  17. Microbial processes in radioactive waste repository

    International Nuclear Information System (INIS)

    Gazso, L.; Farkas-Galgoczi, G.; Diosi, G.

    2002-01-01

    Microbial processes could potentially affect the performance of a radioactive waste disposal system and related factors that could have an influence on the mobility of radionuclides are outlined. Analytical methods, including sampling of water, rock and surface swabs from a potential disposal site, are described and the quantitative as well as qualitative experimental results obtained are given. Although the results contribute to an understanding of the impact of microbial processes on deep geological disposal of nuclear waste, there is not yet sufficient information for a model which will predict the consequences of these processes. (author)

  18. Microbial additives in the composting process

    Directory of Open Access Journals (Sweden)

    Noelly de Queiroz Ribeiro

    Full Text Available ABSTRACT Composting is the process of natural degradation of organic matter carried out by environmental microorganisms whose metabolic activities cause the mineralization and partial humification of substances in the pile. This compost can be beneficially applied to the soil as organic fertilizer in horticulture and agriculture. The number of studies involving microbial inoculants has been growing, and they aim to improve processes such as composting. However, the behavior of these inoculants and other microorganisms during the composting process have not yet been described. In this context, this work aimed to investigate the effects of using a microbial inoculum that can improve the composting process and to follow the bacterial population dynamics throughout the process using the high-resolution melt (HRM technique. To do so, we analysed four compost piles inoculated with Bacillus cereus, Bacillus megaterium, B. cereus + B. megaterium and a control with no inoculum. The analyses were carried out using samples collected at different stages of the process (5th to 110th days. The results showed that the bacterial inocula influenced the process of composting, altering the breakdown of cellulose and hemicelluloses and causing alterations to the temperature and nitrogen levels throughout the composting process. The use of a universal primer (rDNA 16S allowed to follow the microbial succession during the process. However, the design of a specific primer is necessary to follow the inoculum throughout the composting process with more accuracy.

  19. Microbial Flora of Partially Processed Periwinkles (Tympantotonus ...

    African Journals Online (AJOL)

    A survey of microbial flora of partially processed periwinkles (Tympanotonus fuscatus) sold in six markets in Port Harcourt was undertaken for twelve weeks. Results show that all samples of periwinkles were contaminated with Staphylococcus aureus, Bacillus sp., Escherichia coil, Staphepidermidis sp., Micrococcus sp., ...

  20. Multitrophic microbial interactions for eco- and agro-biotechnological processes: theory and practice.

    Science.gov (United States)

    Saleem, Muhammad; Moe, Luke A

    2014-10-01

    Multitrophic level microbial loop interactions mediated by protist predators, bacteria, and viruses drive eco- and agro-biotechnological processes such as bioremediation, wastewater treatment, plant growth promotion, and ecosystem functioning. To what extent these microbial interactions are context-dependent in performing biotechnological and ecosystem processes remains largely unstudied. Theory-driven research may advance the understanding of eco-evolutionary processes underlying the patterns and functioning of microbial interactions for successful development of microbe-based biotechnologies for real world applications. This could also be a great avenue to test the validity or limitations of ecology theory for managing diverse microbial resources in an era of altering microbial niches, multitrophic interactions, and microbial diversity loss caused by climate and land use changes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Something new from something old? Fracking stimulated microbial processes

    Science.gov (United States)

    Wrighton, K. C.; Daly, R. A.; Hoyt, D.; Trexler, R.; McRae, J.; Wilkins, M.; Mouser, P. J.

    2015-12-01

    Hydraulic fracturing, colloquially known as "fracking", is employed for effective gas and oil recovery in deep shales. This process injects organisms and liquids from the surface into the deep subsurface (~2500 m), exposing microorganisms to high pressures, elevated temperatures, chemical additives, and brine-level salinities. Here we use assembly-based metagenomics to create a metabolic blueprint from an energy-producing Marcellus shale well over a 328-day period. Using this approach we ask the question: What abiotic and biotic factors drive microbial metabolism and thus biogeochemical cycling during natural gas extraction? We found that after 49 days, increased salinity in produced waters corresponded to a shift in the microbial community, with only organisms that encode salinity adaptations detected. We posit that organic compatible solutes, produced by organisms adapting to increased salinity, fuels a methylamine-driven ecosystem in fractured shale. This metabolic network ultimately results in biogenic methane production from members of Methanohalophilus and Methanolobus. Proton NMR validated these genomic hypotheses, with mono-methylamine being highest in the input material, but detected throughout the sampling. Beyond abiotic constraints, our genomic investigations revealed that viruses can be linked to key members of the microbial community, potentially releasing methylamine osmoprotectants and impacting bacterial strain variation. Collectively our results indicate that adaptation to high salinity, metabolism in the absence of oxidized electron acceptors, and viral predation are controlling factors mediating microbial community metabolism during hydraulic fracturing of the deep subsurface.

  2. Microbial processes in a clay repository

    Energy Technology Data Exchange (ETDEWEB)

    Canniere, Pierre de [Federal Agency of Nuclear Control (FANC), Brussels (Belgium); Meleshyn, Artur [Gesellschaft fuer Anlagen- und Reaktorsicherheit mbH (GRS), Braunschweig (Germany)

    2013-07-01

    The safety of a deep geologic repository (DGR) for nuclear waste must be ensured for geological times exceeding human imagination taking into account large uncertainties. The long-term effects of complex biogeochemical processes potentially affecting the integrity and the long-term safety of engineered barriers might still be unknown. The aim of this presentation is to give a general overview of some microbial processes which have contributed to shape the Earth since probably billions of years and whose unexpected consequences for nuclear waste disposal should be appropriately tackled. (orig.)

  3. Microbial processes in radioactive waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, Karsten [Goeteborg Univ. (Sweden). Dept. of Cell and Molecular Biology, Microbiology

    2000-04-15

    Independent scientific work has unambiguously demonstrated life to be present in most deep geological formations investigated, down to depths of several kilometres. Microbial processes have consequently become an integral part of the performance safety assessment of high-level radioactive waste (HLW) repositories. This report presents the research record from the last decade of the microbiology research programme of the Swedish Nuclear Fuel and Waste Management Company (SKB) and gives current perspectives of microbial processes in HLW disposal. The goal of the microbiology programme is to understand how microbes may interact with the performance of a future HLW repository. First, for those who are not so familiar with microbes and their ways of living, the concept of 'microbe' is briefly defined. Then, the main characteristics of recognised microbial assemblage and microbial growth, activity and survival are given. The main part of the report summarises data collected during the research period of 1987-1999 and interpretations of these data. Short summaries introduce the research tasks, followed by reviews of the results and insight gained. Sulphate-reducing bacteria (SRB) produce sulphide and have commonly been observed in groundwater environments typical of Swedish HLW repositories. Consequently, the potential for sulphide corrosion of the copper canisters surrounding the HLW must be considered. The interface between the copper canister and the buffer is of special concern. Despite the fact that nowhere are the environmental constraints for life as strong as here, it has been suggested that SRB could survive and locally produce sulphide in concentrations large enough to cause damage to the canister. Experiments conducted thus far have indicated the opposite. Early studies in the research programme revealed previously unknown microbial ecosystems in igneous rock aquifers at depths exceeding 1000 m. This discovery triggered a thorough exploration of the

  4. Microbial processes in radioactive waste disposal

    International Nuclear Information System (INIS)

    Pedersen, Karsten

    2000-04-01

    Independent scientific work has unambiguously demonstrated life to be present in most deep geological formations investigated, down to depths of several kilometres. Microbial processes have consequently become an integral part of the performance safety assessment of high-level radioactive waste (HLW) repositories. This report presents the research record from the last decade of the microbiology research programme of the Swedish Nuclear Fuel and Waste Management Company (SKB) and gives current perspectives of microbial processes in HLW disposal. The goal of the microbiology programme is to understand how microbes may interact with the performance of a future HLW repository. First, for those who are not so familiar with microbes and their ways of living, the concept of 'microbe' is briefly defined. Then, the main characteristics of recognised microbial assemblage and microbial growth, activity and survival are given. The main part of the report summarises data collected during the research period of 1987-1999 and interpretations of these data. Short summaries introduce the research tasks, followed by reviews of the results and insight gained. Sulphate-reducing bacteria (SRB) produce sulphide and have commonly been observed in groundwater environments typical of Swedish HLW repositories. Consequently, the potential for sulphide corrosion of the copper canisters surrounding the HLW must be considered. The interface between the copper canister and the buffer is of special concern. Despite the fact that nowhere are the environmental constraints for life as strong as here, it has been suggested that SRB could survive and locally produce sulphide in concentrations large enough to cause damage to the canister. Experiments conducted thus far have indicated the opposite. Early studies in the research programme revealed previously unknown microbial ecosystems in igneous rock aquifers at depths exceeding 1000 m. This discovery triggered a thorough exploration of the

  5. The microbially mediated soil organic carbon loss under degenerative succession in an alpine meadow.

    Science.gov (United States)

    Zhang, Yuguang; Liu, Xiao; Cong, Jing; Lu, Hui; Sheng, Yuyu; Wang, Xiulei; Li, Diqiang; Liu, Xueduan; Yin, Huaqun; Zhou, Jizhong; Deng, Ye

    2017-07-01

    Land-cover change has long been recognized as having marked effect on the amount of soil organic carbon (SOC). However, the microbially mediated processes and mechanisms on SOC are still unclear. In this study, the soil samples in a degenerative succession from alpine meadow to alpine steppe meadow in the Qinghai-Tibetan Plateau were analysed using high-throughput technologies, including Illumina sequencing and geochip functional gene arrays. The soil microbial community structure and diversity were significantly (p carbon degradation genes (e.g., pectin and hemicellulose) was significantly higher in alpine steppe meadow than in alpine meadow, but the relative abundance of soil recalcitrant carbon degradation genes (e.g., chitin and lignin) showed the opposite tendency. The Biolog Ecoplate experiment showed that microbially mediated soil carbon utilization was more active in alpine steppe meadow than in alpine meadow. Consequently, more soil labile carbon might be decomposed in alpine steppe meadow than in alpine meadow. Therefore, the degenerative succession of alpine meadow because of climate change or anthropogenic activities would most likely decrease SOC and nutrients medicated by changing soil microbial community structure and their functional potentials for carbon decomposition. © 2017 John Wiley & Sons Ltd.

  6. Solving Microbial Spoilage Problems in Processed Foods

    Science.gov (United States)

    Clavero, Rocelle

    This chapter surveys common microbial food spoilage processes. The chapter is organized by food products and includes sections addressing spoilage in meat, poultry, fish; dairy products (milk, butter, cheese); beverage products; bakery products; canned foods; fruit and confectionery products; and emulsions. It addresses the isolation and identification of spoilage organisms and provides several case studies as examples. It introduces various organisms responsible for spoilage including Gram-positive lactic acid bacteria, Gram-negative aerobic bacteria, yeasts, molds, and fungal contaminants. Throughout the chapter, attention is given to when, where, and how spoilage organisms enter the food processing chain. Troubleshooting techniques are suggested. The effect (or lack of effect) of heating, dehydration, pH change, cooling, and sealing on various organisms is explained throughout. The chapter contains four tables that connect specific organisms to various spoilage manifestations in a variety of food products.

  7. Microbial consortia in meat processing environments

    Science.gov (United States)

    Alessandria, V.; Rantsiou, K.; Cavallero, M. C.; Riva, S.; Cocolin, L.

    2017-09-01

    Microbial contamination in food processing plants can play a fundamental role in food quality and safety. The description of the microbial consortia in the meat processing environment is important since it is a first step in understanding possible routes of product contamination. Furthermore, it may contribute in the development of sanitation programs for effective pathogen removal. The purpose of this study was to characterize the type of microbiota in the environment of meat processing plants: the microbiota of three different meat plants was studied by both traditional and molecular methods (PCR-DGGE) in two different periods. Different levels of contamination emerged between the three plants as well as between the two sampling periods. Conventional methods of killing free-living bacteria through antimicrobial agents and disinfection are often ineffective against bacteria within a biofilm. The use of gas-discharge plasmas potentially can offer a good alternative to conventional sterilization methods. The purpose of this study was to measure the effectiveness of Atmospheric Pressure Plasma (APP) surface treatments against bacteria in biofilms. Biofilms produced by three different L. monocytogenes strains on stainless steel surface were subjected to three different conditions (power, exposure time) of APP. Our results showed how most of the culturable cells are inactivated after the Plasma exposure but the RNA analysis by qPCR highlighted the entrance of the cells in the viable-but non culturable (VBNC) state, confirming the hypothesis that cells are damaged after plasma treatment, but in a first step, still remain alive. The understanding of the effects of APP on the L. monocytogenes biofilm can improve the development of sanitation programs with the use of APP for effective pathogen removal.

  8. Mess management in microbial ecology: Rhetorical processes of disciplinary integration

    Science.gov (United States)

    McCracken, Christopher W.

    As interdisciplinary work becomes more common in the sciences, research into the rhetorical processes mediating disciplinary integration becomes more vital. This dissertation, which takes as its subject the integration of microbiology and ecology, combines a postplural approach to rhetoric of science research with Victor Turner's "social drama" analysis and a third-generation activity theory methodological framework to identify conceptual and practical conflicts in interdisciplinary work and describe how, through visual and verbal communication, scientists negotiate these conflicts. First, to understand the conflicting disciplinary principles that might impede integration, the author conducts a Turnerian analysis of a disciplinary conflict that took place in the 1960s and 70s, during which American ecologists and biologists debated whether they should participate in the International Biological Program (IBP). Participation in the IBP ultimately contributed to the emergence of ecology as a discipline distinct from biology, and Turnerian social drama analysis of the debate surrounding participation lays bare the conflicting principles separating biology and ecology. Second, to answer the question of how these conflicting principles are negotiated in practice, the author reports on a yearlong qualitative study of scientists working in a microbial ecology laboratory. Focusing specifically on two case studies from this fieldwork that illustrate the key concept of textually mediated disciplinary integration, the author's analysis demonstrates how scientific objects emerge in differently situated practices, and how these objects manage to cohere despite their multiplicity through textually mediated rhetorical processes of calibration and alignment.

  9. Minimally processed vegetable salads: microbial quality evaluation.

    Science.gov (United States)

    Fröder, Hans; Martins, Cecília Geraldes; De Souza, Katia Leani Oliveira; Landgraf, Mariza; Franco, Bernadette D G M; Destro, Maria Teresa

    2007-05-01

    The increasing demand for fresh fruits and vegetables and for convenience foods is causing an expansion of the market share for minimally processed vegetables. Among the more common pathogenic microorganisms that can be transmitted to humans by these products are Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella. The aim of this study was to evaluate the microbial quality of a selection of minimally processed vegetables. A total of 181 samples of minimally processed leafy salads were collected from retailers in the city of Sao Paulo, Brazil. Counts of total coliforms, fecal coliforms, Enterobacteriaceae, psychrotrophic microorganisms, and Salmonella were conducted for 133 samples. L. monocytogenes was assessed in 181 samples using the BAX System and by plating the enrichment broth onto Palcam and Oxford agars. Suspected Listeria colonies were submitted to classical biochemical tests. Populations of psychrotrophic microorganisms >10(6) CFU/g were found in 51% of the 133 samples, and Enterobacteriaceae populations between 10(5) and 106 CFU/g were found in 42% of the samples. Fecal coliform concentrations higher than 10(2) CFU/g (Brazilian standard) were found in 97 (73%) of the samples, and Salmonella was detected in 4 (3%) of the samples. Two of the Salmonella-positive samples had minimally processed vegetables had poor microbiological quality, and these products could be a vehicle for pathogens such as Salmonella and L. monocytogenes.

  10. Microbial ecology to manage processes in environmental biotechnology.

    Science.gov (United States)

    Rittmann, Bruce E

    2006-06-01

    Microbial ecology and environmental biotechnology are inherently tied to each other. The concepts and tools of microbial ecology are the basis for managing processes in environmental biotechnology; and these processes provide interesting ecosystems to advance the concepts and tools of microbial ecology. Revolutionary advancements in molecular tools to understand the structure and function of microbial communities are bolstering the power of microbial ecology. A push from advances in modern materials along with a pull from a societal need to become more sustainable is enabling environmental biotechnology to create novel processes. How do these two fields work together? Five principles illuminate the way: (i) aim for big benefits; (ii) develop and apply more powerful tools to understand microbial communities; (iii) follow the electrons; (iv) retain slow-growing biomass; and (v) integrate, integrate, integrate.

  11. Microbial production of scleroglucan and downstream processing

    Directory of Open Access Journals (Sweden)

    Natalia Alejandra Castillo

    2015-10-01

    Full Text Available Synthetic petroleum-based polymers and natural plant polymers have the disadvantage of restricted sources, in addition to the non-biodegradability of the former ones. In contrast, eco-sustainable microbial polysaccharides, of low-cost and standardized production, represent an alternative to address this situation. With a strong global market, they attracted worldwide attention because of their novel and unique physico-chemical properties as well as varied industrial applications, and many of them are promptly becoming economically competitive. Scleroglucan, a beta-1,3-beta-1,6-glucan secreted by Sclerotium fungi, exhibits high potential for commercialization and may show different branching frequency, side-chain length and/or molecular weight depending on the producing strain or culture conditions. Water-solubility, viscosifying ability and wide stability over temperature, pH and salinity make scleroglucan useful for different biotechnological (enhanced oil recovery, food additives, drug delivery, cosmetic and pharmaceutical products, biocompatible materials, etc., and biomedical (immunoceutical, antitumor, etc. applications. It can be copiously produced at bioreactor scale under standardized conditions, where a high EPS concentration normally governs the process optimization. Operative and nutritional conditions, as well as the incidence of scleroglucan downstream processing will be discussed in this chapter. The relevance of using standardized inocula from selected strains and experiences concerning the intricate scleroglucan scaling-up will be also herein outlined.

  12. What carries a mediation process? Configural analysis of mediation.

    Science.gov (United States)

    von Eye, Alexander; Mun, Eun Young; Mair, Patrick

    2009-09-01

    Mediation is a process that links a predictor and a criterion via a mediator variable. Mediation can be full or partial. This well-established definition operates at the level of variables even if they are categorical. In this article, two new approaches to the analysis of mediation are proposed. Both of these approaches focus on the analysis of categorical variables. The first involves mediation analysis at the level of configurations instead of variables. Thus, mediation can be incorporated into the arsenal of methods of analysis for person-oriented research. Second, it is proposed that Configural Frequency Analysis (CFA) can be used for both exploration and confirmation of mediation relationships among categorical variables. The implications of using CFA are first that mediation hypotheses can be tested at the level of individual configurations instead of variables. Second, this approach leaves the door open for different types of mediation processes to exist within the same set. Using a data example, it is illustrated that aggregate-level analysis can overlook mediation processes that operate at the level of individual configurations.

  13. Biotechnological Processes in Microbial Amylase Production.

    Science.gov (United States)

    Gopinath, Subash C B; Anbu, Periasamy; Arshad, M K Md; Lakshmipriya, Thangavel; Voon, Chun Hong; Hashim, Uda; Chinni, Suresh V

    2017-01-01

    Amylase is an important and indispensable enzyme that plays a pivotal role in the field of biotechnology. It is produced mainly from microbial sources and is used in many industries. Industrial sectors with top-down and bottom-up approaches are currently focusing on improving microbial amylase production levels by implementing bioengineering technologies. The further support of energy consumption studies, such as those on thermodynamics, pinch technology, and environment-friendly technologies, has hastened the large-scale production of the enzyme. Herein, the importance of microbial (bacteria and fungi) amylase is discussed along with its production methods from the laboratory to industrial scales.

  14. Biotechnological Processes in Microbial Amylase Production

    Directory of Open Access Journals (Sweden)

    Subash C. B. Gopinath

    2017-01-01

    Full Text Available Amylase is an important and indispensable enzyme that plays a pivotal role in the field of biotechnology. It is produced mainly from microbial sources and is used in many industries. Industrial sectors with top-down and bottom-up approaches are currently focusing on improving microbial amylase production levels by implementing bioengineering technologies. The further support of energy consumption studies, such as those on thermodynamics, pinch technology, and environment-friendly technologies, has hastened the large-scale production of the enzyme. Herein, the importance of microbial (bacteria and fungi amylase is discussed along with its production methods from the laboratory to industrial scales.

  15. A marine microbial consortium apparently mediating anaerobic oxidation of methane

    DEFF Research Database (Denmark)

    Boetius, A.; Ravenschlag, K.; Schubert, CJ

    2000-01-01

    microorganisms mediating this reaction have not yet been isolated, and the pathway of anaerobic oxidation of methane is insufficiently understood. Recent data suggest that certain archaea reverse the process of methanogenesis by interaction with sulphate-reducing bacteria(5-7). Here we provide microscopic...... cells and are surrounded by sulphate-reducing bacteria. These aggregates were abundant in gas-hydrate-rich sediments with extremely high rates of methane-based sulphate reduction, and apparently mediate anaerobic oxidation of methane.......A large fraction of globally produced methane is converted to CO2 by anaerobic oxidation in marine sediments(1). Strong geochemical evidence for net methane consumption in anoxic sediments is based on methane profiles(2), radiotracer experiments(3) and stable carbon isotope data(4). But the elusive...

  16. The benzoquinone-mediated electrochemical microbial biosensor for water biotoxicity assay

    International Nuclear Information System (INIS)

    Li, Jiuming; Yu, Yuan; Wang, Yuning; Qian, Jun; Zhi, Jinfang

    2013-01-01

    Graphical abstract: The mediator can participate in microorganism respiration, accept the electrons from respiratory chains, and therefore be reduced by microorganism. The re-oxidization currents of mediators on electrode can reflect the microbial activity, and when respiration is suppressed by toxicants, it can be detected by the resulting change of currents. Unlike other biotoxicity tests, which record the toxic effect after a fixed time for incubation of biocomponents and toxicants, this mediated whole cell biosensor can provide a real-time monitor of the microbial activity during the measurement. -- Abstract: A simple mediated microbial biosensor providing real-time monitoring of water quality and evaluation of biotoxicity was fabricated by entrapping Escherichia coli (E. coli) cells in gelatin on glassy carbon electrode with benzoquinone as the redox mediator. The biotoxicity assay was based on the respiratory activity of E. coli cells estimated by the oxidation current of microbially reduced benzoquinone. The neutrality and lipophilicity rendered benzoquinone better efficiency than ferricyanide in mediated microbial reactions. After the optimization of preparation conditions, the prepared microbial biosensors have measured several common toxicants with different concentrations. In addition, the biotoxicity of binary mixtures of heavy metals and wastewater were investigated. The fabricated biosensor exhibited good repeatability and stability in the biotoxicity measurements

  17. Effects of acid deposition on microbial processes in natural waters

    International Nuclear Information System (INIS)

    Gilmour, C.C.

    1992-01-01

    Biogeochemical processes mediated by microorganisms are not adversely affected by the acidification of natural waters to the same extent as are the life cycles of higher organisms. Basic processes, e.g., primary production and organic matter decomposition, are not slowed in moderately acidified systems and do not generally decline above a pH of 5. More specifically, the individual components of the carbon, nitrogen, and sulfur cycles are, with few exceptions, also acid resistant. The influence of acid deposition on microbial processes is more often stimulation of nitrogen and sulfur cycling, often leading to alkalinity production, which mitigates the effect of strong acid deposition. Bacterial sulfate reduction and denitrification in sediments are two of the major processes that can be stimulated by sulfate and nitrate deposition, respectively, and result in ANC (acid-neutralizing capacity) generation. One of the negative effects of acid deposition is increased mobilization and bioaccumulation of some metals. Bacteria appear to play an important role, especially in mercury cycling, with acidification leading to increased bacterial methylation of mercury and subsequent bioaccumulation in higher organisms

  18. Microbial profile and critical control points during processing of 'robo ...

    African Journals Online (AJOL)

    Microbial profile and critical control points during processing of 'robo' snack from ... the relevant critical control points especially in relation to raw materials and ... to the quality of the various raw ingredients used were the roasting using earthen

  19. New method for characterizing electron mediators in microbial systems using a thin-layer twin-working electrode cell.

    Science.gov (United States)

    Hassan, Md Mahamudul; Cheng, Ka Yu; Ho, Goen; Cord-Ruwisch, Ralf

    2017-01-15

    Microbial biofilms are significant ecosystems where the existence of redox gradients drive electron transfer often via soluble electron mediators. This study describes the use of two interfacing working electrodes (WEs) to simulate redox gradients within close proximity (250µm) for the detection and quantification of electron mediators. By using a common counter and reference electrode, the potentials of the two WEs were independently controlled to maintain a suitable "voltage window", which enabled simultaneous oxidation and reduction of electron mediators as evidenced by the concurrent anodic and cathodic currents, respectively. To validate the method, the electrochemical properties of different mediators (hexacyanoferrate, HCF, riboflavin, RF) were characterized by stepwise shifting the "voltage window" (ranging between 25 and 200mV) within a range of potentials after steady equilibrium current of both WEs was established. The resulting differences in electrical currents between the two WEs were recorded across a defined potential spectrum (between -1V and +0.5V vs. Ag/AgCl). Results indicated that the technique enabled identification (by the distinct peak locations at the potential scale) and quantification (by the peak of current) of the mediators for individual species as well as in an aqueous mixture. It enabled a precise determination of mid-potentials of the externally added mediators (HCF, RF) and mediators produced by pyocyanin-producing Pseudomonas aeruginosa (WACC 91) culture. The twin working electrode described is particularly suitable for studying mediator-dependent microbial electron transfer processes or simulating redox gradients as they exist in microbial biofilms. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Microbial Transglutaminase in Noodle and Pasta Processing

    DEFF Research Database (Denmark)

    Gharibzahedi, Seyed Mohammad Taghi; Yousefi, Shima; Chronakis, Ioannis S.

    2017-01-01

    -formulations for noodles and pasta products based on microbial transglutaminase (MTGase) can guarantee the shelf life extension with minimum quality losses. The current review focuses on recent trends and future prospects of MTGase utilization in the structural matrix of noodles and pasta products and represents......Nowadays, there is an aggressive rate in consumption of noodles and pasta products throughout the world. Consumer acceptability and preference of these functional products can be promoted by the discovery of novel knowledge to improve their formulation and quality. The development of fortified...... from new microbial sources. The high potential of MTGase in developing commercial noodles and pasta products is successfully demonstrated. MTGase by modifying the crystallinity or molecular structure via covalent crosslinks between protein molecules strengthens the doughs stability and the textural...

  1. Microbial production of bulk chemicals: development of anaerobic processes

    NARCIS (Netherlands)

    Weusthuis, R.A.; Lamot, I.; Oost, van der J.; Sanders, J.P.M.

    2011-01-01

    nnovative fermentation processes are necessary for the cost-effective production of bulk chemicals from renewable resources. Current microbial processes are either anaerobic processes, with high yield and productivity, or less-efficient aerobic processes. Oxygen utilization plays an important role

  2. Modeling microbial processes in porous media

    Science.gov (United States)

    Murphy, Ellyn M.; Ginn, Timothy R.

    The incorporation of microbial processes into reactive transport models has generally proceeded along two separate lines of investigation: (1) transport of bacteria as inert colloids in porous media, and (2) the biodegradation of dissolved contaminants by a stationary phase of bacteria. Research over the last decade has indicated that these processes are closely linked. This linkage may occur when a change in metabolic activity alters the attachment/detachment rates of bacteria to surfaces, either promoting or retarding bacterial transport in a groundwater-contaminant plume. Changes in metabolic activity, in turn, are controlled by the time of exposure of the microbes to electron acceptors/donor and other components affecting activity. Similarly, metabolic activity can affect the reversibility of attachment, depending on the residence time of active microbes. Thus, improvements in quantitative analysis of active subsurface biota necessitate direct linkages between substrate availability, metabolic activity, growth, and attachment/detachment rates. This linkage requires both a detailed understanding of the biological processes and robust quantitative representations of these processes that can be tested experimentally. This paper presents an overview of current approaches used to represent physicochemical and biological processes in porous media, along with new conceptual approaches that link metabolic activity with partitioning of the microorganism between the aqueous and solid phases. Résumé L'introduction des processus microbiologiques dans des modèles de transport réactif a généralement suivi deux voies différentes de recherches: (1) le transport de bactéries sous forme de colloïdes inertes en milieu poreux, et (2) la biodégradation de polluants dissous par une phase stationnaire de bactéries. Les recherches conduites au cours des dix dernières années indiquent que ces processus sont intimement liés. Cette liaison peut intervenir lorsqu

  3. Integrated hydrogen production process from cellulose by combining dark fermentation, microbial fuel cells, and a microbial electrolysis cell

    KAUST Repository

    Wang, Aijie; Sun, Dan; Cao, Guangli; Wang, Haoyu; Ren, Nanqi; Wu, Wei-Min; Logan, Bruce E.

    2011-01-01

    Hydrogen gas production from cellulose was investigated using an integrated hydrogen production process consisting of a dark fermentation reactor and microbial fuel cells (MFCs) as power sources for a microbial electrolysis cell (MEC). Two MFCs

  4. Microbial processes in banded iron formation deposition

    DEFF Research Database (Denmark)

    Posth, Nicole; Konhauser, Kurt; Kappler, Andreas

    2013-01-01

    , remains unresolved. Evidence of an anoxic Earth with only localized oxic areas until the Great Oxidation Event ca 2·45 to 2·32 Ga makes the investigation of O2-independent mechanisms for banded iron formation deposition relevant. Recent studies have explored the long-standing proposition that Archean......Banded iron formations have been studied for decades, particularly regarding their potential as archives of the Precambrian environment. In spite of this effort, the mechanism of their deposition and, specifically, the role that microbes played in the precipitation of banded iron formation minerals...... banded iron formations may have been formed, and diagenetically modified, by anaerobic microbial metabolisms. These efforts encompass a wide array of approaches including isotope, ecophysiological and phylogeny studies, molecular and mineral marker analysis, and sedimentological reconstructions. Herein...

  5. Developing and using artificial soils to analyze soil microbial processes

    Science.gov (United States)

    Gao, X.; Cheng, H. Y.; Boynton, L.; Masiello, C. A.; Silberg, J. J.

    2017-12-01

    Microbial diversity and function in soils are governed by soil characteristics such as mineral composition, particles size and aggregations, soil organic matter (SOM), and availability of nutrients and H2O. The spatial and temporal heterogeneity of soils creates a range of niches (hotspots) differing in the availability of O2, H2O, and nutrients, which shapes microbial activities at scales ranging from nanometer to landscape. Synthetic biologists often examine microbial response trigged by their environment conditions in nutrient-rich aqueous media using single strain microbes. While these studies provided useful insight in the role of soil microbes in important soil biogeochemical processes (e.g., C cycling, N cycling, etc.), the results obtained from the over-simplified model systems are often not applicable natural soil systems. On the contrary, soil microbiologists examine microbial processes in natural soils using longer incubation time. However, due to its physical, chemical and biological complexity of natural soils, it is often difficult to examine soil characteristics independently and understand how each characteristic influences soil microbial activities and their corresponding soil functioning. Therefore, it is necessary to bridge the gap and develop a model matrix to exclude unpredictable influences from the environment while still reliably mimicking real environmental conditions. The objective of this study is to design a range of ecologically-relevant artificial soils with varying texture (particle size distribution), structure, mineralogy, SOM content, and nutrient heterogeneity. We thoroughly characterize the artificial soils for pH, active surface area and surface morphology, cation exchange capacity (CEC), and water retention curve. We demonstrate the effectiveness of the artificial soils as useful matrix for microbial processes, such as microbial growth and horizontal gene transfer (HGT), using the gas-reporting biosensors recently developed in

  6. Volatile-mediated suppression of plant pathogens is related to soil properties and microbial community composition

    NARCIS (Netherlands)

    Van Agtmaal, M.; Straathof, A.L.; Termorshuizen, Aad J; Lievens, Bart; Hoffland, Ellis; De Boer, W.

    2018-01-01

    There is increasing evidence that the soil microbial community produces a suite of volatile organic compounds that suppress plant pathogens. However, it remains unknown which soil properties and management practices influence volatile-mediated pathogen suppression. The aim of this study was to

  7. Volatile-mediated suppression of plant pathogens is related to soil properties and microbial community composition

    NARCIS (Netherlands)

    Agtmaal, van Maaike; Straathof, Angela L.; Termorshuizen, Aad; Lievens, Bart; Hoffland, Ellis; Boer, de Wietse

    2018-01-01

    There is increasing evidence that the soil microbial community produces a suite of volatile organic compounds that suppress plant pathogens. However, it remains unknown which soil properties and management practices influence volatile-mediated pathogen suppression. The aim of this study was to

  8. Microbial diversity and their roles in the vinegar fermentation process.

    Science.gov (United States)

    Li, Sha; Li, Pan; Feng, Feng; Luo, Li-Xin

    2015-06-01

    Vinegar is one of the oldest acetic acid-diluted solution products in the world. It is produced from any fermentable sugary substrate by various fermentation methods. The final vinegar products possess unique functions, which are endowed with many kinds of compounds formed in the fermentation process. The quality of vinegar is determined by many factors, especially by the raw materials and microbial diversity involved in vinegar fermentation. Given that metabolic products from the fermenting strains are directly related to the quality of the final products of vinegar, the microbial diversity and features of the dominant strains involved in different fermentation stages should be analyzed to improve the strains and stabilize fermentation. Moreover, although numerous microbiological studies have been conducted to examine the process of vinegar fermentation, knowledge about microbial diversity and their roles involved in fermentation is still fragmentary and not systematic enough. Therefore, in this review, the dominant microorganism species involved in the stages of alcoholic fermentation and acetic acid fermentation of dissimilar vinegars were summarized. We also summarized various physicochemical properties and crucial compounds in disparate types of vinegar. Furthermore, the merits and drawbacks of vital fermentation methods were generalized. Finally, we described in detail the relationships among microbial diversity, raw materials, fermentation methods, physicochemical properties, compounds, functionality, and final quality of vinegar. The integration of this information can provide us a detailed map about the microbial diversity and function involved in vinegar fermentation.

  9. Microbial degradation processes in radioactive waste repository and in nuclear fuel storage areas

    International Nuclear Information System (INIS)

    Wolfram, J.H.; Rogers, R.D.; Gazso, L.G.

    1997-01-01

    The intent of the workshop organizers was to convene experts in the fields of corrosion and spent nuclear fuels. The major points which evolved from the interaction of microbiologists, material scientists, and fuel storage experts are as follows: Corrosion of basin components as well as fuel containers or cladding is occurring; Water chemistry monitoring, if done in the storage facility does not take into account the microbial component; Microbial influenced corrosion is an area that many have not considered to be an important contributor in the aging of metallurgical materials especially those exposed to a radiation field; Many observations indicate that there is a microbial or biological presence in the storage facilities but these observations have not been correlated with any deterioration or aging phenomena taking place in the storage facility; The sessions on the fundamentals of microbial influenced corrosion and biofilm pointed out that these phenomena are real, occurring on similar materials in other industries and probably are occurring in the wet storage of spent fuel; All agreed that more monitoring, testing, and education in the field of biological mediate processes be performed and financially supported; Loosing the integrity of fuel assemblies can only cause problems, relating to the future disposition of the fuel, safety concerns, and environmental issues; In other rad waste scenarios, biological processes may be playing a role, for instance in the mobility of radionuclides in soil, decomposition of organic materials of the rad waste, gas production, etc. The fundamental scientific presentations discussed the full gamut of microbial processes that relate to biological mediated effects on metallic and non-metallic materials used in the storage and containment of radioactive materials

  10. Microbially-Mediated Precipitation of Calcium Carbonate Nanoparticles.

    Science.gov (United States)

    Kang, Ser Ku; Roh, Yul

    2016-02-01

    The objective of this study was to investigate the biomineralization of carbonate minerals using microorganisms (Wu Do-1) enriched from rhodoliths. A 16S rRNA sequence analysis showed that Wu Do-1 mainly contained Proteus mirabilis. The pH decreased from 6.5 to 5.3 over the first 4 days of incubation due to microbial oxidation of organic acids, after which it increased to 7.8 over the remaining incubation period. XRD analysis showed that the precipitates were Mg-rich cal- cite (MgxCa(1-x)CO3), whereas no precipitates were formed without the addition of Wu Do-1 in D-1 medium. SEM-EDS analyses showed that the Mg-rich calcite had a rhombohedron shape and consisted of Ca, Si and Mg with an extracelluar polymeric substance (EPS). In addition, TEM-EDS analyses revealed they were hexagon in shape, 500-700 nm in size, and composed of Ca, Mg, C, and O. These results indicated that Wu Do-1 induced precipitation of Mg-rich calcite on the cell walls and EPS via the accumulation of Ca and/or Mg ions. Therefore, microbial precipitation of carbonate nanoparticles may play an important role in metal and carbon biogeochemistry, as well as in carbon sequestration in natural environments.

  11. Microbial contamination associated with the processing of ...

    African Journals Online (AJOL)

    This study aimed to assess the microbiological contamination and quality of tchachanga, a roasted meat braised product processed at traditional scale in Benin, West Africa. A survey was performed to collect samples of tchachanga and data related to hygienic conditions of the roasted meat processing environment. A total ...

  12. Immune-mediated diseases and microbial exposure in early life

    DEFF Research Database (Denmark)

    Bisgaard, H; Bønnelykke, K; Stokholm, Jacob

    2014-01-01

    The non-communicable disease pandemic includes immune-mediated diseases such as asthma and allergy, which are likely originating in early life where the immature immune system is prone to alterations caused by the exposome. The timing of exposure seems critical for the developing immune system...

  13. Anaerobic microbial processes for energy conservation and biotransformation of pollutants

    NARCIS (Netherlands)

    Luz Ferreira Martins Paulo, da Lara

    2017-01-01

    Anaerobic microbial processes are commonly applied in the treatment of domestic and industrial wastewaters. Anaerobic digestion (AD) of wastewater has received a great deal of attention, but many aspects related to the complex interactions between microorganism, and how that is affected by the

  14. Microbial Herd Protection Mediated by Antagonistic Interaction in Polymicrobial Communities

    Science.gov (United States)

    Wong, Megan J. Q.; Liang, Xiaoye; Smart, Matt; Tang, Le; Moore, Richard; Ingalls, Brian

    2016-01-01

    ABSTRACT In host and natural environments, microbes often exist in complex multispecies communities. The molecular mechanisms through which such communities develop and persist, despite significant antagonistic interactions between species, are not well understood. The type VI secretion system (T6SS) is a lethal weapon commonly employed by Gram-negative bacteria to inhibit neighboring species through the delivery of toxic effectors. It is well established that intraspecies protection is conferred by immunity proteins that neutralize effector toxicities. In contrast, the mechanisms for interspecies protection are not clear. Here we use two T6SS-active antagonistic bacterial species, Aeromonas hydrophila and Vibrio cholerae, to demonstrate that interspecies protection is dependent on effectors. A. hydrophila and V. cholerae do not share conserved immunity genes but could coexist equally in a mixture. However, mutants lacking the T6SS or effectors were effectively eliminated by the competing wild-type strain. Time-lapse microscopic analyses showed that mutually lethal interactions drive the segregation of mixed species into distinct single-species clusters by eliminating interspersed single cells. Cluster formation provides herd protection by abolishing lethal interactions inside each cluster and restricting the interactions to the boundary. Using an agent-based modeling approach, we simulated the antagonistic interactions of two hypothetical species. The resulting simulations recapitulated our experimental observations. These results provide mechanistic insights regarding the general role of microbial weapons in determining the structures of complex multispecies communities. IMPORTANCE Investigating the warfare of microbes allows us to better understand the ecological relationships in complex microbial communities such as the human microbiota. Here we use the T6SS, a deadly bacterial weapon, as a model to demonstrate the importance of lethal interactions in

  15. Microbial herd protection mediated by antagonistic interaction in polymicrobial communities.

    Science.gov (United States)

    Wong, Megan; Liang, Xiaoye; Smart, Matt; Tang, Le; Moore, Richard; Ingalls, Brian; Dong, Tao G

    2016-09-16

    In the host and natural environments, microbes often exist in complex multispecies communities. The molecular mechanisms through which such communities develop and persist - despite significant antagonistic interactions between species - are not well understood. The type VI secretion system (T6SS) is a lethal weapon commonly employed by Gram-negative bacteria to inhibit neighboring species through delivery of toxic effectors. It is well established that intra-species protection is conferred by immunity proteins that neutralize effector toxicities. By contrast, the mechanisms for interspecies protection are not clear. Here we use two T6SS active antagonistic bacteria, Aeromonas hydrophila (AH) and Vibrio cholerae (VC), to demonstrate that interspecies protection is dependent on effectors. AH and VC do not share conserved immunity genes but could equally co-exist in a mixture. However, mutants lacking the T6SS or effectors were effectively eliminated by the other competing wild type. Time-lapse microscopy analyses show that mutually lethal interactions drive the segregation of mixed species into distinct single-species clusters by eliminating interspersed single cells. Cluster formation provides herd protection by abolishing lethal interaction inside each cluster and restricting it to the boundary. Using an agent-based modeling approach, we simulated the antagonistic interactions of two hypothetical species. The resulting simulations recapitulate our experimental observation. These results provide mechanistic insights for the general role of microbial weapons in determining the structures of complex multispecies communities. Investigating the warfare of microbes allows us to better understand the ecological relationships in complex microbial communities such as the human microbiota. Here we use the T6SS, a deadly bacterial weapon, as a model to demonstrate the importance of lethal interactions in determining community structures and exchange of genetic materials

  16. Soil microbial community composition is correlated to soil carbon processing along a boreal wetland formation gradient

    Science.gov (United States)

    Chapman, Eric; Cadillo-Quiroz, Hinsby; Childers, Daniel L.; Turetsky, Merritt R.; Waldrop, Mark P.

    2017-01-01

    Climate change is modifying global biogeochemical cycles. Microbial communities play an integral role in soil biogeochemical cycles; knowledge about microbial composition helps provide a mechanistic understanding of these ecosystem-level phenomena. Next generation sequencing approaches were used to investigate changes in microbial functional groups during ecosystem development, in response to climate change, in northern boreal wetlands. A gradient of wetlands that developed following permafrost degradation was used to characterize changes in the soil microbial communities that mediate C cycling: a bog representing an “undisturbed” system with intact permafrost, and a younger bog and an older bog that formed following the disturbance of permafrost thaw. Reference 16S rRNA databases and several diversity indices were used to assess structural differences among these communities, to assess relationships between soil microbial community composition and various environmental variables including redox potential and pH. Rates of potential CO2 and CH4 gas production were quantified to correlate sequence data with gas flux. The abundance of organic C degraders was highest in the youngest bog, suggesting higher rates of microbial processes, including potential CH4 production. In addition, alpha diversity was also highest in the youngest bog, which seemed to be related to a more neutral pH and a lower redox potential. These results could potentially be driven by increased niche differentiation in anaerobic soils. These results suggest that ecosystem structure, which was largely driven by changes in edaphic and plant community characteristics between the “undisturbed” permafrost bog and the two bogs formed following permafrost thaw, strongly influenced microbial function.

  17. Microbial safety of minimally processed foods

    National Research Council Canada - National Science Library

    Novak, John S; Sapers, Gerald M; Juneja, Vijay K

    2003-01-01

    ...-course meals. All are expected to be portioned and minimally processed to balance the naturalness of unaltered foods with a concern for safety. Yet the responsibility for proper food preparation and handling remains with the naïve modern consumer, who may be less adept in food preparations than his or her less sophisticated ancestors. As a result,...

  18. Increased resiliency and activity of microbial mediated carbon cycling enzymes in diversified bioenergy cropping systems

    Science.gov (United States)

    Upton, R.; Bach, E.; Hofmockel, K. S.

    2017-12-01

    Microbes are mediators of soil carbon (C) and are influenced in membership and activity by nitrogen (N) fertilization and inter-annual abiotic factors. Microbial communities and their extracellular enzyme activities (EEA) are important parameters that influence ecosystem C cycling properties and are often included in microbial explicit C cycling models. In an effort to generate model relevant, empirical findings, we investigated how both microbial community structure and C degrading enzyme activity are influenced by inter-annual variability and N inputs in bioenergy crops. Our study was performed at the Comparison of Biofuel Systems field-site from 2011 to 2014, in three bioenergy cropping systems, continuous corn (CC) and two restored prairies, both fertilized (FP) and unfertilized (P). We hypothesized microbial community structure would diverge during the prairie restoration, leading to changes in C cycling enzymes over time. Using a sequencing approach (16S and ITS) we determined the bacterial and fungal community structure response to the cropping system, fertilization, and inter-annual variability. Additionally, we used EEA of β-glucosidase, cellobiohydrolase, and β-xylosidase to determine inter-annual and ecosystem impacts on microbial activity. Our results show cropping system was a main effect for microbial community structure, with corn diverging from both prairies to be less diverse. Inter-annual changes showed that a drought occurring in 2012 significantly impacted microbial community structure in both the P and CC, decreasing microbial richness. However, FP increased in microbial richness, suggesting the application of N increased resiliency to drought. Similarly, the only year in which C cycling enzymes were impacted by ecosystem was 2012, with FP supporting higher potential enzymatic activity then CC and P. The highest EEA across all ecosystems occurred in 2014, suggesting the continued root biomass and litter build-up in this no till system

  19. Microbial Genetic Memory to Study Heterogeneous Soil Processes

    Science.gov (United States)

    Fulk, E. M.; Silberg, J. J.; Masiello, C. A.

    2017-12-01

    Microbes can be engineered to sense environmental conditions and produce a detectable output. These microbial biosensors have traditionally used visual outputs that are difficult to detect in soil. However, recently developed gas-producing biosensors can be used to noninvasively monitor complex soil processes such as horizontal gene transfer or cell-cell signaling. While these biosensors report on the fraction of a microbial population exposed to a process or chemical signal at the time of measurement, they do not record a "memory" of past exposure. Synthetic biologists have recently developed a suite of genetically encoded memory circuits capable of reporting on historical exposure to the signal rather than just the current state. We will provide an overview of the microbial memory systems that may prove useful to studying microbial decision-making in response to environmental conditions. Simple memory circuits can give a yes/no report of any past exposure to the signal (for example anaerobic conditions, osmotic stress, or high nitrate concentrations). More complicated systems can report on the order of exposure of a population to multiple signals or the experiences of spatially distinct populations, such as those in root vs. bulk soil. We will report on proof-of-concept experiments showing the function of a simple permanent memory system in soil-cultured microbes, and we will highlight additional applications. Finally, we will discuss challenges still to be addressed in applying these memory circuits for biogeochemical studies.

  20. Processes mediating expertise in air traffic control

    NARCIS (Netherlands)

    Van Meeuwen, Ludo; Jarodzka, Halszka; Brand-Gruwel, Saskia; Van Merriënboer, Jeroen; De Bock, Jeano; Kirschner, Paul A.

    2010-01-01

    Van Meeuwen, L., Jarodzka, H., Brand-Gruwel, S., Van Merriënboer, J. J. G., De Bock, J. J. P. R., & Kirschner, P. A. (2010, August). Processes mediating expertise in air traffic control. Meeting of the EARLI SIG6/7 Instructional Design and Learning and Instruction with Computers, Ulm, Germany.

  1. Processes mediating expertise in air traffic control

    NARCIS (Netherlands)

    Van Meeuwen, Ludo; Jarodzka, Halszka; Brand-Gruwel, Saskia; Van Merriënboer, Jeroen; De Bock, Jeano; Kirschner, Paul A.

    2011-01-01

    Van Meeuwen, L. W., Jarodzka, H., Brand-Gruwel, S., Van Merriënboer, J. J. G., De Bock, J. J. P. R., & Kirschner, P. A. (2010, September). Processes mediating expertise in air traffic control. Poster presented at the European Association for Aviation Psychology Conference, Budapest.

  2. Elimination of pyraclostrobin by simultaneous microbial degradation coupled with the Fenton process in microbial fuel cells and the microbial community.

    Science.gov (United States)

    Zhao, Huanhuan; Kong, Chui-Hua

    2018-06-01

    The elimination of pyraclostrobin by simultaneous microbial degradation and Fenton oxidation was achieved in a microbial fuel cell (MFC) system. After 12 h of incubation, the removal rate of pyraclostrobin was 1.4 mg/L/h at the anode and 1.7 mg/L/h at the cathode. The pyraclostrobin concentration was less than the detection limit (0.1 mg/L) after 72 h at the anode and 24 h at the cathode. The air flow rate, temperature, and pH of the catholyte had significant effects on the generation of H 2 O 2 . The maximum production of H 2 O 2 was 1.2 mg/L after reaction for 20 h during the Fenton process. Microbial community analysis indicated that functional bacteria in the genera Chryseobacterium, Stenotrophomonas, Arcobacter, and Comamonas were predominant in the anodic biofilm. In conclusion, the MFC-Fenton system provides an effective approach for treating environmental contaminants. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Microbial ecology of the Agaricus bisporus mushroom cropping process.

    Science.gov (United States)

    McGee, Conor F

    2018-02-01

    Agaricus bisporus is the most widely cultivated mushroom species in the world. Cultivation is commenced by inoculating beds of semi-pasteurised composted organic substrate with a pure spawn of A. bisporus. The A. bisporus mycelium subsequently colonises the composted substrate by degrading the organic material to release nutrients. A layer of peat, often called "casing soil", is laid upon the surface of the composted substrate to induce the development of the mushroom crop and maintain compost environmental conditions. Extensive research has been conducted investigating the biochemistry and genetics of A. bisporus throughout the cultivation process; however, little is currently known about the wider microbial ecology that co-inhabits the composted substrate and casing layers. The compost and casing microbial communities are known to play important roles in the mushroom production process. Microbial species present in the compost and casing are known for (1) being an important source of nitrogen for the A. bisporus mycelium, (2) releasing sugar residues through the degradation of the wheat straw in the composted substrate, (3) playing a critical role in inducing development of the A. bisporus fruiting bodies and (4) acting as pathogens by parasitising the mushroom mycelium/crop. Despite a long history of research into the mushroom cropping process, an extensive review of the microbial communities present in the compost and casing has not as of yet been undertaken. The aim of this review is to provide a comprehensive summary of the literature investigating the compost and casing microbial communities throughout cultivation of the A. bisporus mushroom crop.

  4. Plant stimulation of soil microbial community succession: how sequential expression mediates soil carbon stabilization and turnover

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Mary [Univ. of California, Berkeley, CA (United States)

    2015-03-31

    It is now understood that most plant C is utilized or transformed by soil microorganisms en route to stabilization. Hence the composition of microbial communities that mediate decomposition and transformation of root C is critical, as are the metabolic capabilities of these communities. The change in composition and function of the C-transforming microbial communities over time in effect defines the biological component of soil C stabilization. Our research was designed to test 2 general hypotheses; the first two hypotheses are discussed first; H1: Root-exudate interactions with soil microbial populations results in the expression of enzymatic capacities for macromolecular, complex carbon decomposition; and H2: Microbial communities surrounding roots undergo taxonomic succession linked to functional gene activities as roots grow, mature, and decompose in soil. Over the term of the project we made significant progress in 1) quantifying the temporal pattern of root interactions with the soil decomposing community and 2) characterizing the role of root exudates in mediating these interactions.

  5. Coupling Spatiotemporal Community Assembly Processes to Changes in Microbial Metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Graham, Emily B.; Crump, Alex R.; Resch, Charles T.; Fansler, Sarah; Arntzen, Evan; Kennedy, David W.; Fredrickson, Jim K.; Stegen, James C.

    2016-12-16

    Community assembly processes govern shifts in species abundances in response to environmental change, yet our understanding of assembly remains largely decoupled from ecosystem function. Here, we test hypotheses regarding assembly and function across space and time using hyporheic microbial communities as a model system. We pair sampling of two habitat types through hydrologic fluctuation with null modeling and multivariate statistics. We demonstrate that dual selective pressures assimilate to generate compositional changes at distinct timescales among habitat types, resulting in contrasting associations of Betaproteobacteria and Thaumarchaeota with selection and with seasonal changes in aerobic metabolism. Our results culminate in a conceptual model in which selection from contrasting environments regulates taxon abundance and ecosystem function through time, with increases in function when oscillating selection opposes stable selective pressures. Our model is applicable within both macrobial and microbial ecology and presents an avenue for assimilating community assembly processes into predictions of ecosystem function.

  6. Spectral Characteristics of Salinized Soils during Microbial Remediation Processes.

    Science.gov (United States)

    Ma, Chuang; Shen, Guang-rong; Zhi, Yue-e; Wang, Zi-jun; Zhu, Yun; Li, Xian-hua

    2015-09-01

    In this study, the spectral reflectance of saline soils, the associated soil salt content (SSC) and the concentrations of salt ions were measured and analysed by tracing the container microbial remediation experiments for saline soil (main salt is sodium chloride) of Dongying City, Shandong Province. The sensitive spectral reflectance bands of saline soils to SSC, Cl- and Na+ in the process of microbial remediation were analysed. The average-dimension reduction of these bands was conducted by using a combination of correlation coefficient and decision coefficient, and by gradually narrowing the sampling interval method. Results showed that the tendency and magnitude of the average spectral reflectance in all bands of saline soils during the total remediation processes were nearly consistent with SSC and with Cl- coocentration, respectively. The degree of salinity of the soil, including SSC and salt ion concentrations, had a significant positive correlation with the spectral reflectance of all bands, particularly in the near-infrared band. The optimal spectral bands of SSC were 1370 to 1445 nm and 1447 to 1608 nm, whereas the optimal spectral bands of Cl- and Na+ were 1336 to 1461 nm and 1471 to 1561 nm, respectively. The relationship model among SSC, soil salt ion concentrations (Cl- and Na+) and soil spectral reflectance of the corresponding optimal spectral band was established. The largest R2 of relationship model between SSC and the average reflectance of associated optimal band reached to 0.95, and RMSEC and RMSEP were 1.076 and 0.591, respectively. Significant statistical analysis of salt factors and soil reflectance for different microbial remediation processes indicated that the spectral response characteristics and sensitivity of SSC to soil reflectance, which implied the feasibility of high spectrum test on soil microbial remediation monitoring, also provided the basis for quick nondestructive monitoring soil bioremediation process by soil spectral

  7. Electricity generation by Enterobacter cloacae SU-1 in mediator less microbial fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Samrot, Antony V.; Senthilkumar, P.; Pavankumar, K.; Akilandeswari, G.C. [Department of Biotechnology, Sathyabama University, Rajiv Gandhi Salai, Chennai, Tamilnadu (India); Rajalakshmi, N.; Dhathathreyan, K.S. [Center for Fuel Cell Technology ARCI, IITM Research Park, Phase I, 2nd Floor, 6 Kanagam Road, Tharamani, Chennai 600 113, Tamilnadu (India)

    2010-08-15

    We have investigated a Enterobacter cloacae SU-1, bacteria for mediator less microbial fuel cell with different carbon sources and is found to be more effective as the microorganism is able to transfer electrons directly (exo-electrogenic organism) via the cytochromes or the ubiquinone. These carriers of electrons are in form of stable reversible redox couples, not biologically degraded and not toxic to cell. The major advantage of mediator less microbial fuel cells emphasize that additives in the anolyte is not compatible with the purpose of water purification. The anode chamber with the bacteria is maintained under anaerobic conditions so that the bacteria will undergo anaerobic biochemical pathways like Glycolysis, TCA cycle, Electron Transport Chain (ETC) where electrons and protons are released. Here protons are released in TCA cycle and whereas electrons are released from ETC. The mediator less microbial fuel cell delivered an open circuit potential (OCP) of 0.93 V and power of 3 mW/sq cm. During power generation from the microbes, there was a drop in coulombic efficiency in terms of fluctuations during drawing power, as the carbon source is being utilized for the cell growth. (author)

  8. Effect of long-term fertilization on humic redox mediators in multiple microbial redox reactions.

    Science.gov (United States)

    Guo, Peng; Zhang, Chunfang; Wang, Yi; Yu, Xinwei; Zhang, Zhichao; Zhang, Dongdong

    2018-03-01

    This study investigated the effects of different long-term fertilizations on humic substances (HSs), humic acids (HAs) and humins, functioning as redox mediators for various microbial redox biotransformations, including 2,2',4,4',5,5'- hexachlorobiphenyl (PCB 153 ) dechlorination, dissimilatory iron reduction, and nitrate reduction, and their electron-mediating natures. The redox activity of HSs for various microbial redox metabolisms was substantially enhanced by long-term application of organic fertilizer (pig manure). As a redox mediator, only humin extracted from soils with organic fertilizer amendment (OF-HM) maintained microbial PCB 153 dechlorination activity (1.03 μM PCB 153 removal), and corresponding HA (OF-HA) most effectively enhanced iron reduction and nitrate reduction by Shewanella putrefaciens. Electrochemical analysis confirmed the enhancement of their electron transfer capacity and redox properties. Fourier transform infrared analysis showed that C=C and C=O bonds, and carboxylic or phenolic groups in HSs might be the redox functional groups affected by fertilization. This research enhances our understanding of the influence of anthropogenic fertility on the biogeochemical cycling of elements and in situ remediation ability in agroecosystems through microorganisms' metabolisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. OPTIMIZATION OF FLOCCULATION PROCESS BY MICROBIAL COAGULANT IN RIVER WATER

    Directory of Open Access Journals (Sweden)

    Fatin Nabilah Murad

    2017-12-01

    Full Text Available The existing process of coagulation and flocculation are using chemicals that known as cationic coagulant such as alum, ferric sulfate, calcium oxide, and organic polymers.  Thus, this study concentrates on optimizing of flocculation process by microbial coagulant in river water. Turbidity and suspended solids are the main constraints of river water quality in Malaysia. Hence, a study is proposed to produce microbial coagulants isolated locally for river water treatment. The chosen microbe used as the bioflocculant producer is Aspergillus niger. The parameters to optimization in the flocculation process were pH, bioflocculant dosage and effluent concentration. The research was done in the jar test process and the process parameters for maximum turbidity removal was validated. The highest flocculating activity was obtained on day seven of cultivation in the supernatant. The optimum pH and bioflocculant dosage for an optimize sedimentation process were between 4-5 and 2-3 mL for 0.3 g/L of effluent concentration respectively. The model was validated by using a river water sample from Sg. Pusu and the result showed that the model was acceptable to evaluate the bioflocculation process.

  10. Microbial mediated preparation, characterization and optimization of gold nanoparticles.

    Science.gov (United States)

    Barabadi, Hamed; Honary, Soheila; Ebrahimi, Pouneh; Mohammadi, Milad Ali; Alizadeh, Ahad; Naghibi, Farzaneh

    2014-01-01

    The need for eco-friendly and cost effective methods for nanoparticles synthesis is developing interest in biological approaches which are free from the use of toxic chemicals as byproducts. This study aimed to biosynthesize and optimize the size of gold nanoparticles which produced by biotechnological method using Penicillium crustosum isolated from soil. Initially, Penicillium crustosum was grown in fluid czapek dox broth on shaker at 28 °C and 200 rpm for ten days and then the supernatant was separated from the mycelia to convert AuCl₄ solution into gold nanoparticles. The synthesized nanoparticles in the optimum conditions were formed with fairly well-defined dimensions and good monodispersity. The characterizations were done by using different methods (UV-Visible Spectroscopy, Fluorescence, FT-IR, AFM (Atomic Force Microscopy) and DLS (Dynamic Light Scattering). The bioconversion was optimized by Box-Behnken experimental design. The results show that the effective factors in this process were concentration of AuCl₄, pH of medium and temperature of shaker incubator. The R(2) value was calculated to be 0.9999 indicating the accuracy and ability of the polynomial model. It can be concluded that the use of multivariate analysis facilitated to find out the optimum conditions for the biosynthesis of gold nanoparticles induced by Penicillium crustosum in a time and cost effective process. The current approach suggested that rapid synthesis of gold nanoparticles would be suitable for developing a biological process for mass scale production of formulations.

  11. Microbial electrolytic disinfection process for highly efficient Escherichia coli inactivation

    DEFF Research Database (Denmark)

    Zhou, Shaofeng; Huang, Shaobin; Li, Xiaohu

    2018-01-01

    extensively studied for recalcitrant organics removal, its application potential towards water disinfection (e.g., inactivation of pathogens) is still unknown. This study investigated the inactivation of Escherichia coli in a microbial electrolysis cell based bio-electro-Fenton system (renamed as microbial......Water quality deterioration caused by a wide variety of recalcitrant organics and pathogenic microorganisms has become a serious concern worldwide. Bio-electro-Fenton systems have been considered as cost-effective and highly efficient water treatment platform technology. While it has been......]OH was identified as one potential mechanism for disinfection. This study successfully demonstrated the feasibility of bio-electro-Fenton process for pathogens inactivation, which offers insight for the future development of sustainable, efficient, and cost-effective biological water treatment technology....

  12. Metabolic engineering of microbial competitive advantage for industrial fermentation processes.

    Science.gov (United States)

    Shaw, A Joe; Lam, Felix H; Hamilton, Maureen; Consiglio, Andrew; MacEwen, Kyle; Brevnova, Elena E; Greenhagen, Emily; LaTouf, W Greg; South, Colin R; van Dijken, Hans; Stephanopoulos, Gregory

    2016-08-05

    Microbial contamination is an obstacle to widespread production of advanced biofuels and chemicals. Current practices such as process sterilization or antibiotic dosage carry excess costs or encourage the development of antibiotic resistance. We engineered Escherichia coli to assimilate melamine, a xenobiotic compound containing nitrogen. After adaptive laboratory evolution to improve pathway efficiency, the engineered strain rapidly outcompeted a control strain when melamine was supplied as the nitrogen source. We additionally engineered the yeasts Saccharomyces cerevisiae and Yarrowia lipolytica to assimilate nitrogen from cyanamide and phosphorus from potassium phosphite, and they outcompeted contaminating strains in several low-cost feedstocks. Supplying essential growth nutrients through xenobiotic or ecologically rare chemicals provides microbial competitive advantage with minimal external risks, given that engineered biocatalysts only have improved fitness within the customized fermentation environment. Copyright © 2016, American Association for the Advancement of Science.

  13. Electricity generation from synthesis gas by microbial processes: CO fermentation and microbial fuel cell technology.

    Science.gov (United States)

    Kim, Daehee; Chang, In Seop

    2009-10-01

    A microbiological process was established to harvest electricity from the carbon monoxide (CO). A CO fermenter was enriched with CO as the sole carbon source. The DGGE/DNA sequencing results showed that Acetobacterium spp. were enriched from the anaerobic digester fluid. After the fermenter was operated under continuous mode, the products were then continuously fed to the microbial fuel cell (MFC) to generate electricity. Even though the conversion yield was quite low, this study proved that synthesis gas (syn-gas) can be converted to electricity with the aid of microbes that do not possess the drawbacks of metal catalysts of conventional methods.

  14. Microbial processes in the Athabasca Oil Sands and their potential applications in microbial enhanced oil recovery.

    Science.gov (United States)

    Harner, N K; Richardson, T L; Thompson, K A; Best, R J; Best, A S; Trevors, J T

    2011-11-01

    The Athabasca Oil Sands are located within the Western Canadian Sedimentary Basin, which covers over 140,200 km(2) of land in Alberta, Canada. The oil sands provide a unique environment for bacteria as a result of the stressors of low water availability and high hydrocarbon concentrations. Understanding the mechanisms bacteria use to tolerate these stresses may aid in our understanding of how hydrocarbon degradation has occurred over geological time, and how these processes and related tolerance mechanisms may be used in biotechnology applications such as microbial enhanced oil recovery (MEOR). The majority of research has focused on microbiology processes in oil reservoirs and oilfields; as such there is a paucity of information specific to oil sands. By studying microbial processes in oil sands there is the potential to use microbes in MEOR applications. This article reviews the microbiology of the Athabasca Oil Sands and the mechanisms bacteria use to tolerate low water and high hydrocarbon availability in oil reservoirs and oilfields, and potential applications in MEOR.

  15. Removal of mercury from coal via a microbial pretreatment process

    Science.gov (United States)

    Borole, Abhijeet P [Knoxville, TN; Hamilton, Choo Y [Knoxville, TN

    2011-08-16

    A process for the removal of mercury from coal prior to combustion is disclosed. The process is based on use of microorganisms to oxidize iron, sulfur and other species binding mercury within the coal, followed by volatilization of mercury by the microorganisms. The microorganisms are from a class of iron and/or sulfur oxidizing bacteria. The process involves contacting coal with the bacteria in a batch or continuous manner. The mercury is first solubilized from the coal, followed by microbial reduction to elemental mercury, which is stripped off by sparging gas and captured by a mercury recovery unit, giving mercury-free coal. The mercury can be recovered in pure form from the sorbents via additional processing.

  16. Evaluation of microbial hazards during creamy cream cheese processing

    Directory of Open Access Journals (Sweden)

    Joanna Żukowska

    2015-04-01

    Full Text Available The purpose of the work was to identify the potential microbial hazards that may occur during the manufacturing process of creamy cream cheese, and to present the means of their elimination or minimization. The analysis demonstrated that among the most crucial stages that should be particularly monitored are: the quality of raw materials, the control of pasteurization and souring parameters as well as temperature of product packaging, ensuring proper storage conditions of the finished product and hygiene throughout the production. Of these, the most critical step in the entire process (critical control points - CCP is a heat treatment process which is pasteurization. On the basis of the analysis, it can be concluded that the monitoring of such a process and consistent adherence to Operational Pre-Condition Pro-grams at the thermisation and centrifuging and later packaging, can help guarantee a safe product and its long shelf life.

  17. Microbial fuel cell treatment of ethanol fermentation process water

    Science.gov (United States)

    Borole, Abhijeet P [Knoxville, TN

    2012-06-05

    The present invention relates to a method for removing inhibitor compounds from a cellulosic biomass-to-ethanol process which includes a pretreatment step of raw cellulosic biomass material and the production of fermentation process water after production and removal of ethanol from a fermentation step, the method comprising contacting said fermentation process water with an anode of a microbial fuel cell, said anode containing microbes thereon which oxidatively degrade one or more of said inhibitor compounds while producing electrical energy or hydrogen from said oxidative degradation, and wherein said anode is in electrical communication with a cathode, and a porous material (such as a porous or cation-permeable membrane) separates said anode and cathode.

  18. Profession of mediator as the professional provider of the mediation process

    Directory of Open Access Journals (Sweden)

    Jernej Šoštar

    2017-03-01

    Full Text Available The civil mediation programme, which is a court-connected programme, established as a form of alternative dispute resolution, is increasingly gaining ground as a field with its own theoretical and practical knowledge, principles and basic rules. Mediation has already set up its own body of knowledge, based on studies, classification of cases and the analyses of the results. In this article, we examine whether in the context of the development of mediation in Slovenia we might already talk about the profession of the mediator, defined as a provider of the mediation process. We examine the court-connected civil mediation and mediators who mediate at the court-connected civil mediation, and define them theoretically. By interviewing the mediation experts and mediators we examine their opinions about mediators and the court mediation. We examine the legal basis for the court-connected mediation programmes in Slovenia as well as in the European Union. Proceeding from our findings we conclude that the legal regulation of the court mediation in Slovenia is well established, and that the mediators of the court-connected civil mediation programmes can be accepted as the professional providers of the mediation process.

  19. Microbial communities, processes and functions in acid mine drainage ecosystems.

    Science.gov (United States)

    Chen, Lin-xing; Huang, Li-nan; Méndez-García, Celia; Kuang, Jia-liang; Hua, Zheng-shuang; Liu, Jun; Shu, Wen-sheng

    2016-04-01

    Acid mine drainage (AMD) is generated from the oxidative dissolution of metal sulfides when water and oxygen are available largely due to human mining activities. This process can be accelerated by indigenous microorganisms. In the last several decades, culture-dependent researches have uncovered and validated the roles of AMD microorganisms in metal sulfides oxidation and acid generation processes, and culture-independent studies have largely revealed the diversity and metabolic potentials and activities of AMD communities, leading towards a full understanding of the microbial diversity, functions and interactions in AMD ecosystems. This review describes the diversity of microorganisms and their functions in AMD ecosystems, and discusses their biotechnological applications in biomining and AMD bioremediation according to their capabilities. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Designing business rules for mediation : a process towards agent-mediated business coordination

    OpenAIRE

    Zhao, Z.; Dignum, M.V.; Dignum, F.P.M.

    2008-01-01

    Business process integration is a very active research area, in which mediation is one of the fundamental architectural choices. Mediators have difficulties to design mediation services that meet the requirements of the different stakeholders. Business rules play an important role in the decision process of mediation. In this paper, we analyze the role of business rules in the decision process, and use some examples to illustrate how business rules should be designed in order to help the deci...

  1. Identifying target processes for microbial electrosynthesis by elementary mode analysis.

    Science.gov (United States)

    Kracke, Frauke; Krömer, Jens O

    2014-12-30

    Microbial electrosynthesis and electro fermentation are techniques that aim to optimize microbial production of chemicals and fuels by regulating the cellular redox balance via interaction with electrodes. While the concept is known for decades major knowledge gaps remain, which make it hard to evaluate its biotechnological potential. Here we present an in silico approach to identify beneficial production processes for electro fermentation by elementary mode analysis. Since the fundamentals of electron transport between electrodes and microbes have not been fully uncovered yet, we propose different options and discuss their impact on biomass and product yields. For the first time 20 different valuable products were screened for their potential to show increased yields during anaerobic electrically enhanced fermentation. Surprisingly we found that an increase in product formation by electrical enhancement is not necessarily dependent on the degree of reduction of the product but rather the metabolic pathway it is derived from. We present a variety of beneficial processes with product yield increases of maximal 36% in reductive and 84% in oxidative fermentations and final theoretical product yields up to 100%. This includes compounds that are already produced at industrial scale such as succinic acid, lysine and diaminopentane as well as potential novel bio-commodities such as isoprene, para-hydroxybenzoic acid and para-aminobenzoic acid. Furthermore, it is shown that the way of electron transport has major impact on achievable biomass and product yields. The coupling of electron transport to energy conservation could be identified as crucial for most processes. This study introduces a powerful tool to determine beneficial substrate and product combinations for electro-fermentation. It also highlights that the maximal yield achievable by bio electrochemical techniques depends strongly on the actual electron transport mechanisms. Therefore it is of great importance to

  2. Strategies to Optimize Microbially-Mediated Mitigation of Greenhouse Gas Emissions from Landfill Cover Soils

    Energy Technology Data Exchange (ETDEWEB)

    Jeremy Semrau; Sung-Woo Lee; Jeongdae Im; Sukhwan Yoon; Michael Barcelona

    2010-09-30

    The overall objective of this project, 'Strategies to Optimize Microbially-Mediated Mitigation of Greenhouse Gas Emissions from Landfill Cover Soils' was to develop effective, efficient, and economic methodologies by which microbial production of nitrous oxide can be minimized while also maximizing microbial consumption of methane in landfill cover soils. A combination of laboratory and field site experiments found that the addition of nitrogen and phenylacetylene stimulated in situ methane oxidation while minimizing nitrous oxide production. Molecular analyses also indicated that methane-oxidizing bacteria may play a significant role in not only removing methane, but in nitrous oxide production as well, although the contribution of ammonia-oxidizing archaea to nitrous oxide production can not be excluded at this time. Future efforts to control both methane and nitrous oxide emissions from landfills as well as from other environments (e.g., agricultural soils) should consider these issues. Finally, a methanotrophic biofiltration system was designed and modeled for the promotion of methanotrophic activity in local methane 'hotspots' such as landfills. Model results as well as economic analyses of these biofilters indicate that the use of methanotrophic biofilters for controlling methane emissions is technically feasible, and provided either the costs of biofilter construction and operation are reduced or the value of CO{sub 2} credits is increased, can also be economically attractive.

  3. The role microbial sulfate reduction in the direct mediation of sedimentary authigenic carbonate precipitation

    Science.gov (United States)

    Turchyn, A. V.; Walker, K.; Sun, X.

    2016-12-01

    The majority of modern deep marine sediments are bathed in water that is undersaturated with respect to calcium carbonate. However, within marine sediments changing chemical conditions, driven largely by the microbial oxidation of organic carbon in the absence of oxygen, lead to supersaturated conditions and drive calcium carbonate precipitation. This sedimentary calcium carbonate is often called `authigenic carbonate', and is found in the form of cements and disseminated crystals within the marine sedimentary pile. As this precipitation of this calcium carbonate is microbially mediated, identifying authigenic carbonate within the geological record and understanding what information its geochemical and/or isotopic signature may hold is key for understanding its importance and what information it may contain past life. However, the modern controls on authigenic carbonate precipitation remain enigmatic because the myriad of microbially mediated reactions occurring within sediments both directly and indirectly impact the proton balance. In this submission we present data from 25 ocean sediment cores spanning the globe where we explore the deviation from the stoichiometrically predicted relationships among alkalinity, calcium and sulfate concentrations. In theory for every mol of organic carbon reduced by sulfate, two mol of alkalinity is produced, and to precipitate subsurface calcium carbonate one mol of calcium is used to consume two mol of alkalinity. We use this data with a model to explore changes in carbonate saturation state with depth below the seafloor. Alkalinity changes in the subsurface are poorly correlated with changes in calcium concentrations, however calcium concentrations are directly and tightly coupled to changes in sulfate concentrations in all studied sites. This suggests a direct role for sulfate reducing bacteria in the precipitation of subsurface carbonate cements.

  4. Temperature regulates deterministic processes and the succession of microbial interactions in anaerobic digestion process

    Czech Academy of Sciences Publication Activity Database

    Lin, Qiang; De Vrieze, J.; Li, Ch.; Li, J.; Li, J.; Yao, M.; Heděnec, Petr; Li, H.; Li, T.; Rui, J.; Frouz, Jan; Li, X.

    2017-01-01

    Roč. 123, October (2017), s. 134-143 ISSN 0043-1354 Institutional support: RVO:60077344 Keywords : anaerobic digestion * deterministic process * microbial interactions * modularity * temperature gradient Subject RIV: DJ - Water Pollution ; Quality OBOR OECD: Water resources Impact factor: 6.942, year: 2016

  5. Estimating and mapping ecological processes influencing microbial community assembly.

    Science.gov (United States)

    Stegen, James C; Lin, Xueju; Fredrickson, Jim K; Konopka, Allan E

    2015-01-01

    Ecological community assembly is governed by a combination of (i) selection resulting from among-taxa differences in performance; (ii) dispersal resulting from organismal movement; and (iii) ecological drift resulting from stochastic changes in population sizes. The relative importance and nature of these processes can vary across environments. Selection can be homogeneous or variable, and while dispersal is a rate, we conceptualize extreme dispersal rates as two categories; dispersal limitation results from limited exchange of organisms among communities, and homogenizing dispersal results from high levels of organism exchange. To estimate the influence and spatial variation of each process we extend a recently developed statistical framework, use a simulation model to evaluate the accuracy of the extended framework, and use the framework to examine subsurface microbial communities over two geologic formations. For each subsurface community we estimate the degree to which it is influenced by homogeneous selection, variable selection, dispersal limitation, and homogenizing dispersal. Our analyses revealed that the relative influences of these ecological processes vary substantially across communities even within a geologic formation. We further identify environmental and spatial features associated with each ecological process, which allowed mapping of spatial variation in ecological-process-influences. The resulting maps provide a new lens through which ecological systems can be understood; in the subsurface system investigated here they revealed that the influence of variable selection was associated with the rate at which redox conditions change with subsurface depth.

  6. Estimating and Mapping Ecological Processes Influencing Microbial Community Assembly

    Directory of Open Access Journals (Sweden)

    James C Stegen

    2015-05-01

    Full Text Available Ecological community assembly is governed by a combination of (i selection resulting from among-taxa differences in performance; (ii dispersal resulting from organismal movement; and (iii ecological drift resulting from stochastic changes in population sizes. The relative importance and nature of these processes can vary across environments. Selection can be homogeneous or variable, and while dispersal is a rate, we conceptualize extreme dispersal rates as two categories; dispersal limitation results from limited exchange of organisms among communities, and homogenizing dispersal results from high levels of organism exchange. To estimate the influence and spatial variation of each process we extend a recently developed statistical framework, use a simulation model to evaluate the accuracy of the extended framework, and use the framework to examine subsurface microbial communities over two geologic formations. For each subsurface community we estimate the degree to which it is influenced by homogeneous selection, variable selection, dispersal limitation, and homogenizing dispersal. Our analyses revealed that the relative influences of these ecological processes vary substantially across communities even within a geologic formation. We further identify environmental and spatial features associated with each ecological process, which allowed mapping of spatial variation in ecological-process-influences. The resulting maps provide a new lens through which ecological systems can be understood; in the subsurface system investigated here they revealed that the influence of variable selection was associated with the rate at which redox conditions change with subsurface depth.

  7. Effect of acid rain on soil microbial processes

    International Nuclear Information System (INIS)

    Myrold, D.D.; Nason, G.E.

    1992-01-01

    Acid rain is real; the pH of precipitation in many areas of the world is below its normal equilibrium value, and concentrations of inorganic N and S are elevated above background. The impact of acid rain on soil microbial processes is less clear. This is largely because of the chemical buffering of the soil ecosystem and the inherent resiliency and redundancy of soil microorganisms. Microorganisms have an amazing capacity to adapt to new situations, which is enhanced by their ability to evolve under selection pressure. Their resilience is a function of both the large number of microorganisms present in a given volume of soil and their high growth rate relative to macroorganisms. This suggests that microorganisms are likely to be able to adapt more quickly to acidification than plants or animals, which may be one reason why symbiotic associations, such as ectomycorrhizae, are more susceptible to acid inputs than their saprophytic counterparts

  8. Development of a high temperature microbial fermentation process for butanol

    Energy Technology Data Exchange (ETDEWEB)

    Jeor, Jeffery D. St. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Reed, David W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Daubaras, Dayna L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thompson, Vicki S. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-08-01

    Transforming renewable biomass into cost-competitive high-performance biofuels and bioproducts is key to the U.S. future energy and chemical needs. Butanol production by microbial fermentation for chemical conversion to polyolefins, elastomers, drop-in jet or diesel fuel, and other chemicals is a promising solution. A high temperature fermentation process could decrease energy costs, capital cost, give higher butanol production, and allow for continuous fermentation. In this paper, we describe our approach to genetically transform Geobacillus caldoxylosiliticus, using a pUCG18 plasmid, for potential insertion of a butanol production pathway. Transformation methods tested were electroporation of electrocompetent cells, ternary conjugation with E. coli donor and helper strains, and protoplast fusion. These methods have not been successful using the current plasmid. Growth controls show cells survive the various methods tested, suggesting the possibility of transformation inhibition from a DNA restriction modification system in G. caldoxylosiliticus, as reported in the literature.

  9. Quantitative Microbial Risk Assessment for in Natural and Processed Cheeses

    Directory of Open Access Journals (Sweden)

    Heeyoung Lee

    2016-08-01

    Full Text Available This study evaluated the risk of Clostridium perfringens (C. perfringens foodborne illness from natural and processed cheeses. Microbial risk assessment in this study was conducted according to four steps: hazard identification, hazard characterization, exposure assessment, and risk characterization. The hazard identification of C. perfringens on cheese was identified through literature, and dose response models were utilized for hazard characterization of the pathogen. For exposure assessment, the prevalence of C. perfringens, storage temperatures, storage time, and annual amounts of cheese consumption were surveyed. Eventually, a simulation model was developed using the collected data and the simulation result was used to estimate the probability of C. perfringens foodborne illness by cheese consumption with @RISK. C. perfringens was determined to be low risk on cheese based on hazard identification, and the exponential model (r = 1.82×10−11 was deemed appropriate for hazard characterization. Annual amounts of natural and processed cheese consumption were 12.40±19.43 g and 19.46±14.39 g, respectively. Since the contamination levels of C. perfringens on natural (0.30 Log CFU/g and processed cheeses (0.45 Log CFU/g were below the detection limit, the initial contamination levels of natural and processed cheeses were estimated by beta distribution (α1 = 1, α2 = 91; α1 = 1, α2 = 309×uniform distribution (a = 0, b = 2; a = 0, b = 2.8 to be −2.35 and −2.73 Log CFU/g, respectively. Moreover, no growth of C. perfringens was observed for exposure assessment to simulated conditions of distribution and storage. These data were used for risk characterization by a simulation model, and the mean values of the probability of C. perfringens foodborne illness by cheese consumption per person per day for natural and processed cheeses were 9.57×10−14 and 3.58×10−14, respectively. These results indicate that probability of C. perfringens

  10. Extracellular Saccharide-Mediated Reduction of Au3+ to Gold Nanoparticles: New Insights for Heavy Metals Biomineralization on Microbial Surfaces.

    Science.gov (United States)

    Kang, Fuxing; Qu, Xiaolei; Alvarez, Pedro J J; Zhu, Dongqiang

    2017-03-07

    Biomineralization is a critical process controlling the biogeochemical cycling, fate, and potential environmental impacts of heavy metals. Despite the indispensability of extracellular polymeric substances (EPS) to microbial life and their ubiquity in soil and aquatic environments, the role played by EPS in the transformation and biomineralization of heavy metals is not well understood. Here, we used gold ion (Au 3+ ) as a model heavy metal ion to quantitatively assess the role of EPS in biomineralization and discern the responsible functional groups. Integrated spectroscopic analyses showed that Au 3+ was readily reduced to zerovalent gold nanoparticles (AuNPs, 2-15 nm in size) in aqueous suspension of Escherichia coli or dissolved EPS extracted from microbes. The majority of AuNPs (95.2%) was formed outside Escherichia coli cells, and the removal of EPS attached to cells pronouncedly suppressed Au 3+ reduction, reflecting the predominance of the extracellular matrix in Au 3+ reduction. XPS, UV-vis, and FTIR analyses corroborated that Au 3+ reduction was mediated by the hemiacetal groups (aldehyde equivalents) of reducing saccharides of EPS. Consistently, the kinetics of AuNP formation obeyed pseudo-second-order reaction kinetics with respect to the concentrations of Au 3+ and the hemiacetal groups in EPS, with minimal dependency on the source of microbial EPS. Our findings indicate a previously overlooked, universally significant contribution of EPS to the reduction, mineralization, and potential detoxification of metal species with high oxidation state.

  11. Microbially mediated transformations of phosphorus in the sea: new views of an old cycle.

    Science.gov (United States)

    Karl, David M

    2014-01-01

    Phosphorus (P) is a required element for life. Its various chemical forms are found throughout the lithosphere and hydrosphere, where they are acted on by numerous abiotic and biotic processes collectively referred to as the P cycle. In the sea, microorganisms are primarily responsible for P assimilation and remineralization, including recently discovered P reduction-oxidation bioenergetic processes that add new complexity to the marine microbial P cycle. Human-induced enhancement of the global P cycle via mining of phosphate-bearing rock will likely influence the pace of P-cycle dynamics, especially in coastal marine habitats. The inextricable link between the P cycle and cycles of other bioelements predicts future impacts on, for example, nitrogen fixation and carbon dioxide sequestration. Additional laboratory and field research is required to build a comprehensive understanding of the marine microbial P cycle.

  12. Long Term Monitoring of Microbial Induced Soil Strengthening Processes

    Science.gov (United States)

    Saneiyan, S.; Ntarlagiannis, D.; Werkema, D. D., Jr.; Colwell, F. S.; Ohan, J.

    2016-12-01

    Soil strengthening/stabilization processes are used to address some of soil quality issues. Microbial induced calcite precipitation (MICP) is a promising soil stabilization process that could offer long term solution by overcoming problems of commonly used methods (e.g. injecting cement slurry). MICP can be applied in larger spatial scales, allowing the enhanced soils to be maintained in an economic sustainable and environmental friendly way. Methods are sought for the long term monitoring of MICP enhanced soils. The spectral induced polarization (SIP) method is one promising method due to sensitivity on such processes and the ability for long term, even autonomous, operation as well as cost effectiveness. Previous laboratory tests showed the sensitivity of the SIP method on soil strengthening as a result of abiotic calcite precipitation. We extended this work to biotic calcite precipitation through MICP. Early results suggest that the MICP formed calcite is denser and could provide improved strengthening capabilities. Our results are supported by geophysical (SIP and shear-wave velocity), geo-chemical and microbiological monitoring. Destructive analysis and visualization (scanning electron imaging - SEM) is expected to provide conclusive evidence on the MICP long term effectiveness.

  13. Microbial ecology and starter culture technology in coffee processing.

    Science.gov (United States)

    Vinícius de Melo Pereira, Gilberto; Soccol, Vanete Thomaz; Brar, Satinder Kaur; Neto, Ensei; Soccol, Carlos Ricardo

    2017-09-02

    Coffee has been for decades the most commercialized food product and most widely consumed beverage in the world, with over 600 billion cups served per year. Before coffee cherries can be traded and processed into a final industrial product, they have to undergo postharvest processing on farms, which have a direct impact on the cost and quality of a coffee. Three different methods can be used for transforming the coffee cherries into beans, known as wet, dry, and semi-dry methods. In all these processing methods, a spontaneous fermentation is carried out in order to eliminate any mucilage still stuck to the beans and helps improve beverage flavor by microbial metabolites. The microorganisms responsible for the fermentation (e.g., yeasts and lactic acid bacteria) can play a number of roles, such as degradation of mucilage (pectinolytic activity), inhibition of mycotoxin-producing fungi growth, and production of flavor-active components. The use of starter cultures (mainly yeast strains) has emerged in recent years as a promising alternative to control the fermentation process and to promote quality development of coffee product. However, scarce information is still available about the effects of controlled starter cultures in coffee fermentation performance and bean quality, making it impossible to use this technology in actual field conditions. A broader knowledge about the ecology, biochemistry, and molecular biology could facilitate the understanding and application of starter cultures for coffee fermentation process. This review provides a comprehensive coverage of these issues, while pointing out new directions for exploiting starter cultures in coffee processing.

  14. Designing business rules for mediation : a process towards agent-mediated business coordination

    NARCIS (Netherlands)

    Zhao, Z.; Dignum, M.V.; Dignum, F.P.M.

    2008-01-01

    Business process integration is a very active research area, in which mediation is one of the fundamental architectural choices. Mediators have difficulties to design mediation services that meet the requirements of the different stakeholders. Business rules play an important role in the

  15. Radiation processing of leafy vegetables to ensure their microbial safety

    International Nuclear Information System (INIS)

    Khade, H.D.; Jain, M.P.; Satyendra, Gautam

    2015-01-01

    Leafy vegetables which are consumed in raw form such as spinach, coriander and mint were found to be heavily burdened with microbial load including presumptive coliform, an indicator of pathogenic contaminations. Total aerobic plate counts in fresh spinach, coriander and mint samples collected from different location of Mumbai and nearby cities were found to be in the order of ∼ 10 7 to ∼ 10 8 CFU/g. In these samples yeast and mould count was in the order of ∼10 5 CFU/g and presumptive coliform in the order of ∼ 10 4 to ∼10 5 CFU/g. As per USFDA coliform load in the food commodity should be nil. The finding thus indicates that these fresh vegetables are not safe for raw consumption. Hence there is utmost need of process which can ensure the safety by reducing their microbial load below permissible level (<10 4 CFU/gm) and coliform load to nil without affecting the appearance and quality of such produce. In this study gamma radiation was used for hygienization of leafy vegetables. The sample were first cleaned in potable water followed by sodium hypochlorite wash (200 ppm for 20 min), air dried, packed in styrofoam based tray, wrapped with cling film and radiation processed at 1 to 2.5 kGy and stored at 4 and 10℃ . Post irradiation microbiological analysis of radiation processed samples was carried out at in 2 kGy irradiated samples total plate count was below ∼10 3 CFU/g and presumptive coliform count was below detectable level. Yeast and mould count in these samples also reduced to below ∼ 10 3 CFU/g. Based on the study the following combination treatment can be given to raw leafy vegetables, washing with potable water (5 min) → sodium hypochlorite (200 ppm 20 min) wash → Air drying → Packaging in styrofoam based tray and wrapping with cling film → Irradiation at 2 kGy → storage at 4℃ . Besides ensuring safety the treatment also resulted in increased shelf life extension of the commodities up to 20 days. (author)

  16. Ant-mediated effects on spruce litter decomposition, solution chemistry, and microbial activity

    DEFF Research Database (Denmark)

    Stadler, B.; Schramm, Andreas; Kalbitz, K.

    2006-01-01

    the effects of ants and aphid honeydew on litter solution of Norway spruce, microbial enzyme activities, and needle decomposition in a field and greenhouse experiment during summer 2003. In the field, low ant densities had relatively little effects on litter solution 30 cm away from a tree trunk...... and %N were not affected by ants or honeydew. Our results suggest that ants have a distinct and immediate effect on solution composition and microbial activity in the litter layer indicating accelerated litter decay whereas the effect of honeydew was insignificant. Keywords: Ants; Decomposition; Formica......Forest management practices often generate clear-cut patches, which may be colonized by ants not present in the same densities in mature forests. In addition to the associated changes in abiotic conditions ants can initiate processes, which do not occur in old-growth stands. Here, we analyse...

  17. Chitosan matrices modified with carbon nanotubes for use in mediated microbial biosensing

    International Nuclear Information System (INIS)

    Demirkol, D.O.; Timur, S.

    2011-01-01

    We describe a microbial sensor based on Pseudomonas fluorescens cells that was prepared by modifying graphite electrodes with chitosan and carbon nanotubes. Chronoamperometry was performed at +0.3 V in the presence of hexacyanoferrate as a mediator and revealed a good response to glucose which is linear in the 1.0 to 5.0 mM concentration range. Linearity was defined by the equation of y = 102.120x-13.279 (R2 = 0.998) (y shows current density as nA. cm-2 and x shows glucose concentration in mM). The effect of the CNTs on the response was compared to that of electrodes made without CNTs. (author)

  18. Microbial mediation of radionuclide transport -significance for the nuclear fuel waste management program

    International Nuclear Information System (INIS)

    Champ, D.R.

    1984-08-01

    The role that microbially catalyzed processes may play in determining, or altering, radionuclide migration is an unresolved question in the Nuclear Fuel Waste Management Program. This report documents the results of a review of the available information on the existence and biochemical capabilities of micro-organisms and the potential for their involvement in processes affecting the migration of radionuclides of interest. The potential was judged sufficient to warrant conducting experiments to assess their role. The outline of an experimental program to address the role of micro-organisms is presented

  19. Insights into the Processing of Carbon by Early Microbial Ecosystems

    Science.gov (United States)

    DesMarais, D.; Bebout, B.; Carpenter, S.; Discipulo, S.; Londry, K.; Habicht, K.; Turk, K.

    2003-01-01

    Interactions between Earth and the biosphere that were crucial for early biological evolution also influenced substantially the processes that circulate C between its reservoirs in the atmosphere, ocean, crust and mantle. The C-13 C-12 values of crustal carbonates and organics have recorded changes both in biological discrimination and in the relative rates of burial of organics and carbonates. A full interpretation of these patterns needs further isotopic studies of microbial ecosystems and individual anaerobes. Thus we measured carbon isotope discrimination during autotrophic and heterotrophic growth of pure cultures of sulfate-reducing bacteria and archaea (SRB and SRA). Discrimination during CO2 assimilation is significantly larger than during heterotrophic growth on lactate or acetate. SRB grown lithoautotrophically consumed less than 3% of available CO2 and exhibited substantial discrimination, as follows: Desulfobacterium autotrophicum (alpha 1.0100 to 1.0123), Desulfobacter hydrogenophilus (alpha = 0.0138), and Desulfotomuculum acetoxidans (alpha = 1.0310). Mixotrophic growth of Desulfovibrio desulfuricans on acetate and CO2 resulted in biomass with delta C-13 composition intermediate to that of the substrates. We have recently extended these experiments to include the thermophilic SRA Archeoglobus spp. Ecological forces also influence isotopic discrimination. Accordingly, we quantified the flow of C and other constituents in modern marine cyanobacterial mats, whose ancestry extends back billions of years. Such ecosystem processes shaped the biosignatures that entered sediments and atmospheres. At Guerrero Negro, BCS, Mexico, we examined mats dominated by Microcoleus (subtidal) and Lyngbya (intertidal to supratidal) cyanobacteria. During 24 hour cycles, we observed the exchange of O2 and dissolved inorganic C (DIC) between mats and the overlying water. Microcoleus mats assimilated near-equal amounts of DIC during the day as they released at night, but

  20. Invasion in microbial communities: Role of community composition and assembly processes

    DEFF Research Database (Denmark)

    Kinnunen, Marta

    of microbial community assembly. Biotic factors include interactions between different microbial groups as well as the community response to alien species – invaders. Microbial invasions can have significant effects on the composition and functioning of resident communities. There is, however, lack......Microbes contribute to all biogeochemical cycles on earth and are responsible for key biological processes that support the survival of plants and animals. There is increased interest in controlling and managing microbial communities in different ecosystems in order to make targeted microbiological...... processes more effective. In order to manage microbial communities, it is essential to understand the factors that shape and influence microbial community composition. In addition to abiotic factors, such as environmental conditions and resource availability, biotic factors also shape the dynamics...

  1. Bioelectricity generation using two chamber microbial fuel cell treating wastewater from food processing.

    Science.gov (United States)

    Mansoorian, Hossein Jafari; Mahvi, Amir Hossein; Jafari, Ahmad Jonidi; Amin, Mohammad Mehdi; Rajabizadeh, Ahmad; Khanjani, Narges

    2013-05-10

    Electricity generation from microbial fuel cells which treat food processing wastewater was investigated in this study. Anaerobic anode and aerobic cathode chambers were separated by a proton exchange membrane in a two-compartment MFC reactor. Buffer solutions and food industry wastewater were used as electrolytes in the anode and cathode chambers, respectively. The produced voltage and current intensity were measured using a digital multimeter. Effluents from the anode compartment were tested for COD, BOD5, NH3, P, TSS, VSS, SO4 and alkalinity. The maximum current density and power production were measured 527mA/m(2) and 230mW/m(2) in the anode area, respectively, at operation organic loading (OLR) of 0.364g COD/l.d. At OLR of 0.182g COD/l.d, maximum voltage and columbic efficiency production were recorded 0.475V and 21%, respectively. Maximum removal efficiency of COD, BOD5, NH3, P, TSS, VSS, SO4 and alkalinity were 86, 79, 73, 18, 68, 62, 30 and 58%, respectively. The results indicated that catalysts and mediator-less microbial fuel cells (CAML-MFC) can be considered as a better choice for simple and complete energy conversion from the wastewater of such industries and also this could be considered as a new method to offset wastewater treatment plant operating costs. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Community Assembly Processes of the Microbial Rare Biosphere.

    Science.gov (United States)

    Jia, Xiu; Dini-Andreote, Francisco; Falcão Salles, Joana

    2018-03-14

    Our planet teems with microorganisms that often present a skewed abundance distribution in a local community, with relatively few dominant species coexisting alongside a high number of rare species. Recent studies have demonstrated that these rare taxa serve as limitless reservoirs of genetic diversity, and perform disproportionate types of functions despite their low abundances. However, relatively little is known about the mechanisms controlling rarity and the processes promoting the development of the rare biosphere. Here, we propose the use of multivariate cut-offs to estimate rare species and phylogenetic null models applied to predefined rare taxa to disentangle the relative influences of ecoevolutionary processes mediating the assembly of the rare biosphere. Importantly, the identification of the factors controlling rare species assemblages is critical for understanding the types of rarity, how the rare biosphere is established, and how rare microorganisms fluctuate over spatiotemporal scales, thus enabling prospective predictions of ecosystem responses. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Effect of Elevated Salt Concentrations on the Aerobic Granular Sludge Process : Linking Microbial Activity with Microbial Community Structure

    NARCIS (Netherlands)

    Bassin, J.P.; Pronk, M.; Muyzer, G.; Kleerebezem, R.; Dezotti, M.; Van Loosdrecht, M.C.M.

    2011-01-01

    The long- and short-term effects of salt on biological nitrogen and phosphorus removal processes were studied in an aerobic granular sludge reactor. The microbial community structure was investigated by PCR-denaturing gradient gel electrophoresis (DGGE) on 16S rRNA and amoA genes. PCR products

  4. The significance of microbial processes in hydrogeology and geochemistry

    Science.gov (United States)

    Chapelle, Francis H.

    Microbial processes affect the chemical composition of groundwater and the hydraulic properties of aquifers in both contaminated and pristine groundwater systems. The patterns of water-chemistry changes that occur depend upon the relative abundance of electron donors and electron acceptors. In many pristine aquifers, where microbial metabolism is limited by the availability of electron donors (usually organic matter), dissolved inorganic carbon (DIC) accumulates slowly along aquifer flow paths and available electron acceptors are consumed sequentially in the order dissolved oxygen >nitrate>Fe(III)>sulfate>CO2 (methanogenesis). In aquifers contaminated by anthropogenic contaminants, an excess of available organic carbon often exists, and microbial metabolism is limited by the availability of electron acceptors. In addition to changes in groundwater chemistry, the solid matrix of the aquifer is affected by microbial processes. The production of carbon dioxide and organic acids can lead to increased mineral solubility, which can lead to the development of secondary porosity and permeability. Conversely, microbial production of carbonate, ferrous iron, and sulfide can result in the precipitation of secondary calcite or pyrite cements that reduce primary porosity and permeability in groundwater systems. Les processus microbiologiques peuvent affecter la composition chimique de l'eau souterraine et les propriétés hydrauliques des nappes aussi bien dans les systèmes aquifères pollués que dans les systèmes indemnes de pollution. Les changements de chimisme des eaux qui se produisent dépendent de l'abondance relative des donneurs et des accepteurs d'électrons. Dans les aquifères non contaminés, où le métabolisme microbien est limité par la disponibilité des donneurs d'électrons (en général la matière organique), le carbone minéral dissous (CMD) s'accumule lentement le long des axes d'écoulement souterrain et les accepteurs d'électrons disponibles sont

  5. Enhanced microbial decolorization of methyl red with oxidized carbon fiber as redox mediator

    Energy Technology Data Exchange (ETDEWEB)

    Emilia Rios-Del Toro, E. [División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica (IPICyT), Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, SLP 78216 (Mexico); Celis, Lourdes B. [División de Geociencias Aplicadas, Instituto Potosino de Investigación Científica y Tecnológica (IPICyT), Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, SLP 78216 (Mexico); Cervantes, Francisco J. [División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica (IPICyT), Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, SLP 78216 (Mexico); Rangel-Mendez, J. Rene, E-mail: rene@ipicyt.edu.mx [División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica (IPICyT), Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, SLP 78216 (Mexico)

    2013-09-15

    Highlights: • Activated carbon fibers (ACFs) act as redox mediator. • Electron accepting capacity increased with oxidation time of ACF. •ACFs increased 8-fold the reduction of methyl red in biological assays. •Biofilm formed on the ACFs partly blocked their redox mediator capacity. -- Abstract: The anaerobic degradation of azo dyes under anaerobic conditions is possible but at a slow rate. Redox mediators (quinones, activated carbon) are used to improve the reduction rate. The aim of this work was to use activated carbon fiber (ACF) as a redox mediator for the anaerobic reduction of the azo dye methyl red. ACF was chemically modified with 8 M HNO{sub 3} to increase its redox-mediating capacity and used in chemical and anaerobic biological batch assays for the reduction of methyl red. ACF increased its redox-mediating capacity up to 3-fold in chemical assays; in biological assays ACF increased the reduction rate up to 8-fold compared to controls without ACF. However, since the ACF served as support for biomass, a biofilm formed on the fiber significantly reduced its redox-mediating capacity; substrate consumption suggested that the electron transport from ACF to methyl red was the rate-limiting step in the process. These results are the first evidence of the role of ACF as a redox mediator in the reductive decolorization of methyl red, in addition to the effect of biofilm attached to ACF on methyl red reduction. Due to the versatile characteristics of ACF and its redox-mediating capacity, carbon fibers could be used in biological wastewater treatment systems to accelerate the reductive transformation of pollutants commonly found in industrial effluents.

  6. Enhanced microbial decolorization of methyl red with oxidized carbon fiber as redox mediator

    International Nuclear Information System (INIS)

    Emilia Rios-Del Toro, E.; Celis, Lourdes B.; Cervantes, Francisco J.; Rangel-Mendez, J. Rene

    2013-01-01

    Highlights: • Activated carbon fibers (ACFs) act as redox mediator. • Electron accepting capacity increased with oxidation time of ACF. •ACFs increased 8-fold the reduction of methyl red in biological assays. •Biofilm formed on the ACFs partly blocked their redox mediator capacity. -- Abstract: The anaerobic degradation of azo dyes under anaerobic conditions is possible but at a slow rate. Redox mediators (quinones, activated carbon) are used to improve the reduction rate. The aim of this work was to use activated carbon fiber (ACF) as a redox mediator for the anaerobic reduction of the azo dye methyl red. ACF was chemically modified with 8 M HNO 3 to increase its redox-mediating capacity and used in chemical and anaerobic biological batch assays for the reduction of methyl red. ACF increased its redox-mediating capacity up to 3-fold in chemical assays; in biological assays ACF increased the reduction rate up to 8-fold compared to controls without ACF. However, since the ACF served as support for biomass, a biofilm formed on the fiber significantly reduced its redox-mediating capacity; substrate consumption suggested that the electron transport from ACF to methyl red was the rate-limiting step in the process. These results are the first evidence of the role of ACF as a redox mediator in the reductive decolorization of methyl red, in addition to the effect of biofilm attached to ACF on methyl red reduction. Due to the versatile characteristics of ACF and its redox-mediating capacity, carbon fibers could be used in biological wastewater treatment systems to accelerate the reductive transformation of pollutants commonly found in industrial effluents

  7. Cross-Sectional Analysis of Longitudinal Mediation Processes.

    Science.gov (United States)

    O'Laughlin, Kristine D; Martin, Monica J; Ferrer, Emilio

    2018-01-01

    Statistical mediation analysis can help to identify and explain the mechanisms behind psychological processes. Examining a set of variables for mediation effects is a ubiquitous process in the social sciences literature; however, despite evidence suggesting that cross-sectional data can misrepresent the mediation of longitudinal processes, cross-sectional analyses continue to be used in this manner. Alternative longitudinal mediation models, including those rooted in a structural equation modeling framework (cross-lagged panel, latent growth curve, and latent difference score models) are currently available and may provide a better representation of mediation processes for longitudinal data. The purpose of this paper is twofold: first, we provide a comparison of cross-sectional and longitudinal mediation models; second, we advocate using models to evaluate mediation effects that capture the temporal sequence of the process under study. Two separate empirical examples are presented to illustrate differences in the conclusions drawn from cross-sectional and longitudinal mediation analyses. Findings from these examples yielded substantial differences in interpretations between the cross-sectional and longitudinal mediation models considered here. Based on these observations, researchers should use caution when attempting to use cross-sectional data in place of longitudinal data for mediation analyses.

  8. Screening of microorganisms for microbial enhanced oil recovery processes

    Energy Technology Data Exchange (ETDEWEB)

    Yonebayashi, H. [Japan National Oil Corp., Tokyo (Japan); Yoshida, S. [Japan Food Research Laboratiories, Tokyo (Japan). Div. of Microbiology; Ono, K. [Japan National Oil Corp., Chiba (Japan). Tech. Research Center; Enomoto, H. [Tohoku University, Sendai (Japan). Dept. of Geoscience and Tech.

    2000-01-01

    The objective of this study is to screen effective microorganisms for the Microbial Enhanced Oil Recovery process (or simply as MEOR). Samples of drilling cuttings, formation water, and soil were collected from domestic drilling sites and oil fields. Moreover, samples of activated-sludge and compost were collected from domestic sewage treatment facility and food treatment facility. At first, microorganisms in samples were investigated by incubation with different media; then they were isolated. By two stage-screening based on metabolizing ability, 4 strains (Bacillus licheniformis TRC-18-2-a, Enterobacter cloacae TRC-322, Bacillus subtilis TRC-4118, and Bacillus subtilis TRC-4126) were isolated as effective microorganisms for oil recovery. B. licheniformis TRC-18-2-a is a multifunctional microorganism possessing excellent surfactant productivity, and in addition it has gas, acid and polymer productivities. E. cloacae TRC-332 has gas and acid producing abilities. B. subtilis TRC-4118 and TRC-4126 are effective biosurfactant producers, and they reduce the interfacial tension to 0.04 and 0.12 dyne/cm, respectively. (author)

  9. Commentary: Mediation Analysis, Causal Process, and Cross-Sectional Data

    Science.gov (United States)

    Shrout, Patrick E.

    2011-01-01

    Maxwell, Cole, and Mitchell (2011) extended the work of Maxwell and Cole (2007), which raised important questions about whether mediation analyses based on cross-sectional data can shed light on longitudinal mediation process. The latest article considers longitudinal processes that can only be partially explained by an intervening variable, and…

  10. Unveiling Microbial Carbon Cycling Processes in Key U.S. Soils using ''Omics''

    Energy Technology Data Exchange (ETDEWEB)

    Myrold, David D. [Oregon State Univ., Corvallis, OR (United States); Bottomely, Peter J. [Oregon State Univ., Corvallis, OR (United States); Jumpponen, Ari [Kansas State Univ., Manhattan, KS (United States); Rice, Charles W. [Kansas State Univ., Manhattan, KS (United States); Zeglin, Lydia H. [Kansas State Univ., Manhattan, KS (United States); David, Maude M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Jansson, Janet K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Prestat, Emmanuel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hettich, Robert L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-09-17

    Soils process and store large amounts of C; however, considerable uncertainty still exists about the details of that influence microbial partitioning of C into soil C pools, and what are the main influential forces that control the fraction of the C input that is stabilized. The soil microbial community is genotypically and phenotypically diverse. Despite our ability to predict the kinds of regional environmental changes that will accompany global climate change, it is not clear how the microbial community will respond to climate-induced modification of precipitation and inter-precipitation intervals, and if this response will affect the fate of C deposited into soil by the local plant community. Part of this uncertainty lies with our ignorance of how the microbial community adapts genotypically and physiologically to changes in soil moisture brought about by shifts in precipitation. Our overarching goal is to harness the power of multiple meta-omics tools to gain greater understanding of the functioning of whole-soil microbial communities and their role in C cycling. We will do this by meeting the following three objectives: 1. Further develop and optimize a combination of meta-omics approaches to study how environmental factors affect microbially-mediated C cycling processes. 2. Determine the impacts of long-term changes in precipitation timing on microbial C cycling using an existing long-term field manipulation of a tallgrass prairie soil. 3. Conduct laboratory experiments that vary moisture and C inputs to confirm field observations of the linkages between microbial communities and C cycling processes. We took advantage of our state-of-the-art expertise in community “omics” to better understand the functioning soil C cycling within the Great Prairie ecosystem, including our ongoing Konza Prairie soil metagenome flagship project at JGI and the unique rainfall manipulation plots (RaMPs) established at this site more than a decade ago. We employed a systems

  11. Relating Anaerobic Digestion Microbial Community and Process Function.

    Science.gov (United States)

    Venkiteshwaran, Kaushik; Bocher, Benjamin; Maki, James; Zitomer, Daniel

    2015-01-01

    Anaerobic digestion (AD) involves a consortium of microorganisms that convert substrates into biogas containing methane for renewable energy. The technology has suffered from the perception of being periodically unstable due to limited understanding of the relationship between microbial community structure and function. The emphasis of this review is to describe microbial communities in digesters and quantitative and qualitative relationships between community structure and digester function. Progress has been made in the past few decades to identify key microorganisms influencing AD. Yet, more work is required to realize robust, quantitative relationships between microbial community structure and functions such as methane production rate and resilience after perturbations. Other promising areas of research for improved AD may include methods to increase/control (1) hydrolysis rate, (2) direct interspecies electron transfer to methanogens, (3) community structure-function relationships of methanogens, (4) methanogenesis via acetate oxidation, and (5) bioaugmentation to study community-activity relationships or improve engineered bioprocesses.

  12. Reprint of Design of synthetic microbial communities for biotechnological production processes.

    Science.gov (United States)

    Jagmann, Nina; Philipp, Bodo

    2014-12-20

    In their natural habitats microorganisms live in multi-species communities, in which the community members exhibit complex metabolic interactions. In contrast, biotechnological production processes catalyzed by microorganisms are usually carried out with single strains in pure cultures. A number of production processes, however, may be more efficiently catalyzed by the concerted action of microbial communities. This review will give an overview of organismic interactions between microbial cells and of biotechnological applications of microbial communities. It focuses on synthetic microbial communities that consist of microorganisms that have been genetically engineered. Design principles for such synthetic communities will be exemplified based on plausible scenarios for biotechnological production processes. These design principles comprise interspecific metabolic interactions via cross-feeding, regulation by interspecific signaling processes via metabolites and autoinducing signal molecules, and spatial structuring of synthetic microbial communities. In particular, the implementation of metabolic interdependencies, of positive feedback regulation and of inducible cell aggregation and biofilm formation will be outlined. Synthetic microbial communities constitute a viable extension of the biotechnological application of metabolically engineered single strains and enlarge the scope of microbial production processes. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Hardiness and the response to stressful situations: Investigating mediating processes

    NARCIS (Netherlands)

    Delahaij, R.; Gaillard, A.W.K.; Dam, K. van

    2010-01-01

    The present study investigated mediating processes that explain how hardiness influences the way people respond to a stressful situation. Coping style and coping self-efficacy were investigated as mediating variables. Using a longitudinal design, hardiness, coping style and coping self-efficacy, and

  14. School Processes Mediate School Compositional Effects: Model Specification and Estimation

    Science.gov (United States)

    Liu, Hongqiang; Van Damme, Jan; Gielen, Sarah; Van Den Noortgate, Wim

    2015-01-01

    School composition effects have been consistently verified, but few studies ever attempted to study how school composition affects school achievement. Based on prior research findings, we employed multilevel mediation modeling to examine whether school processes mediate the effect of school composition upon school outcomes based on the data of 28…

  15. Microbial and Sensory Quality of Freshly Processed and ...

    African Journals Online (AJOL)

    The samples were also evaluated for difference and preference. The study showed that the reconstituted beverage had better microbiological quality with detectable difference between the two samples with the fresh sample being preferred. Key words: Millet grains, Kununzaki, microbial quality, sensory quality. J Food Tech ...

  16. Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji-Won; Rondinone, Adam Justin; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

    2017-09-19

    The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component comprising at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

  17. Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

    Science.gov (United States)

    Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji Won; Rondinone, Adam J.; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

    2014-06-24

    The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component containing at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

  18. Gold nanoparticles produced in situ mediate bioelectricity and hydrogen production in a microbial fuel cell by quantized capacitance charging.

    Science.gov (United States)

    Kalathil, Shafeer; Lee, Jintae; Cho, Moo Hwan

    2013-02-01

    Oppan quantized style: By adding a gold precursor at its cathode, a microbial fuel cell (MFC) is demonstrated to form gold nanoparticles that can be used to simultaneously produce bioelectricity and hydrogen. By exploiting the quantized capacitance charging effect, the gold nanoparticles mediate the production of hydrogen without requiring an external power supply, while the MFC produces a stable power density. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Investigation of Mediational Processes Using Parallel Process Latent Growth Curve Modeling

    Science.gov (United States)

    Cheong, JeeWon; MacKinnon, David P.; Khoo, Siek Toon

    2010-01-01

    This study investigated a method to evaluate mediational processes using latent growth curve modeling. The mediator and the outcome measured across multiple time points were viewed as 2 separate parallel processes. The mediational process was defined as the independent variable influencing the growth of the mediator, which, in turn, affected the growth of the outcome. To illustrate modeling procedures, empirical data from a longitudinal drug prevention program, Adolescents Training and Learning to Avoid Steroids, were used. The program effects on the growth of the mediator and the growth of the outcome were examined first in a 2-group structural equation model. The mediational process was then modeled and tested in a parallel process latent growth curve model by relating the prevention program condition, the growth rate factor of the mediator, and the growth rate factor of the outcome. PMID:20157639

  20. Comparison of seasonal soil microbial process in snow-covered temperate ecosystems of northern China.

    Directory of Open Access Journals (Sweden)

    Xinyue Zhang

    Full Text Available More than half of the earth's terrestrial surface currently experiences seasonal snow cover and soil frost. Winter compositional and functional investigations in soil microbial community are frequently conducted in alpine tundra and boreal forest ecosystems. However, little information on winter microbial biogeochemistry is known from seasonally snow-covered temperate ecosystems. As decomposer microbes may differ in their ability/strategy to efficiently use soil organic carbon (SOC within different phases of the year, understanding seasonal microbial process will increase our knowledge of biogeochemical cycling from the aspect of decomposition rates and corresponding nutrient dynamics. In this study, we measured soil microbial biomass, community composition and potential SOC mineralization rates in winter and summer, from six temperate ecosystems in northern China. Our results showed a clear pattern of increased microbial biomass C to nitrogen (N ratio in most winter soils. Concurrently, a shift in soil microbial community composition occurred with higher fungal to bacterial biomass ratio and gram negative (G- to gram positive (G+ bacterial biomass ratio in winter than in summer. Furthermore, potential SOC mineralization rate was higher in winter than in summer. Our study demonstrated a distinct transition of microbial community structure and function from winter to summer in temperate snow-covered ecosystems. Microbial N immobilization in winter may not be the major contributor for plant growth in the following spring.

  1. Microbially-mediated fluorescent organic matter transformations in the deep ocean

    DEFF Research Database (Denmark)

    Aparicio, Fran L.; Nieto-Cid, Mar; Borrull, Encarna

    2015-01-01

    The refractory nature of marine dissolved organic matter (DOM) increases while it travels from surface waters to the deep ocean. This resistant fraction is in part composed of fluorescent humic-like material, which is relatively difficult to metabolize by deep water prokaryotes, and it can also b....... These findings contribute to the understanding of FDOM variability in deep waters and provide valuable information for studies where fluorescent compounds are used in order to track water masses and/or microbial processes.......The refractory nature of marine dissolved organic matter (DOM) increases while it travels from surface waters to the deep ocean. This resistant fraction is in part composed of fluorescent humic-like material, which is relatively difficult to metabolize by deep water prokaryotes, and it can also...

  2. Microbial extracellular polymeric substances in marine biogeochemical processes

    Digital Repository Service at National Institute of Oceanography (India)

    Bhaskar, P.V.; Bhosle, N.B.

    and are found in free dissolved form, colloids, discreet partcles like TEP and/or associated with particulate matter, including cell aggregates, detritus, biofilms, microbial mats, etc. The chemical composition of EPS is influenced by various factors... of EPS in marine waters. Hence, various aspects of EPS di- cussed hereafter indicate bacterial and/or phyto origin unless specified. Characteristics of EPS Microorganisms grow in free planktonic state16,17 or are ata- ched to surfaces (natural...

  3. Genome-Enabled Modeling of Biogeochemical Processes Predicts Metabolic Dependencies that Connect the Relative Fitness of Microbial Functional Guilds

    Science.gov (United States)

    Brodie, E.; King, E.; Molins, S.; Karaoz, U.; Steefel, C. I.; Banfield, J. F.; Beller, H. R.; Anantharaman, K.; Ligocki, T. J.; Trebotich, D.

    2015-12-01

    Pore-scale processes mediated by microorganisms underlie a range of critical ecosystem services, regulating carbon stability, nutrient flux, and the purification of water. Advances in cultivation-independent approaches now provide us with the ability to reconstruct thousands of genomes from microbial populations from which functional roles may be assigned. With this capability to reveal microbial metabolic potential, the next step is to put these microbes back where they belong to interact with their natural environment, i.e. the pore scale. At this scale, microorganisms communicate, cooperate and compete across their fitness landscapes with communities emerging that feedback on the physical and chemical properties of their environment, ultimately altering the fitness landscape and selecting for new microbial communities with new properties and so on. We have developed a trait-based model of microbial activity that simulates coupled functional guilds that are parameterized with unique combinations of traits that govern fitness under dynamic conditions. Using a reactive transport framework, we simulate the thermodynamics of coupled electron donor-acceptor reactions to predict energy available for cellular maintenance, respiration, biomass development, and enzyme production. From metagenomics, we directly estimate some trait values related to growth and identify the linkage of key traits associated with respiration and fermentation, macromolecule depolymerizing enzymes, and other key functions such as nitrogen fixation. Our simulations were carried out to explore abiotic controls on community emergence such as seasonally fluctuating water table regimes across floodplain organic matter hotspots. Simulations and metagenomic/metatranscriptomic observations highlighted the many dependencies connecting the relative fitness of functional guilds and the importance of chemolithoautotrophic lifestyles. Using an X-Ray microCT-derived soil microaggregate physical model combined

  4. Microbial processes at the beds of glaciers and ice sheets: a look at life below the Whillans Ice Stream

    Science.gov (United States)

    Mikucki, J.; Campen, R.; Vancleave, S.; Scherer, R. P.; Coenen, J. J.; Powell, R. D.; Tulaczyk, S. M.

    2017-12-01

    Groundwater, saturated sediments and hundreds of subglacial lakes exist below the ice sheets of Antarctica. The few Antarctic subglacial environments sampled to date all contain viable microorganisms. This is a significant finding because microbes are known to be key in mediating biogeochemical cycles. In sediments, microbial metabolic activity can also result in byproducts or direct interactions with sediment particles that influence the physical and geochemical characteristics of the matrix they inhabit. Subglacial Lake Whillans (SLW), a fresh water lake under the Whillans Ice Stream that drains into the Ross Sea at its grounding zone, was recently sampled as part of the NSF-funded Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project. Sediments from both SLW and its grounding zone contain microbial taxa related to iron, sulfur, nitrogen and methane oxidizers. In addition to molecular data, biogeochemical measurements and culture based experiments on Whillans sediments support the notion that the system is chemosynthetic with energy derived in part by cycling inorganic compounds. Etch pitting and mineral precipitates on fossil sponge spicules suggest that spicules may also provide microbial nutrients in these environments. Perhaps the most widespread microbial process that affects sediment structure and mineral weathering is the production of extra polymeric substances (EPS). Several phylogenetic groups detected in Whillans sediments are known to produce EPS and we have observed its production in pure cultures enriched directly from these sediments. Our data sheds light on how microbial life persists below the Antarctic Ice Sheet despite extended isolation in icy darkness, and how these microbes may be shaping their environment.

  5. Epigeic earthworms exert a bottleneck effect on microbial communities through gut associated processes.

    Science.gov (United States)

    Gómez-Brandón, María; Aira, Manuel; Lores, Marta; Domínguez, Jorge

    2011-01-01

    Earthworms play a critical role in organic matter decomposition because of the interactions they establish with microorganisms. The ingestion, digestion, assimilation of organic material in the gut and then casting is the first step in earthworm-microorganism interactions. The current knowledge of these direct effects is still limited for epigeic earthworm species, mainly those living in man-made environments. Here we tested whether and to what extent the earthworm Eisenia andrei is capable of altering the microbiological properties of fresh organic matter through gut associated processes; and if these direct effects are related to the earthworm diet. To address these questions we determined the microbial community structure (phospholipid fatty acid profiles) and microbial activity (fluorescein diacetate hydrolysis) in the earthworm casts derived from three types of animal manure (cow, horse and pig manure), which differed in microbial composition. The passage of the organic material through the gut of E. andrei reduced the total microbial biomass irrespective of the type of manure, and resulted in a decrease in bacterial biomass in all the manures; whilst leaving the fungi unaffected in the egested materials. However, unlike the microbial biomass, no such reduction was detected in the total microbial activity of cast samples derived from the pig manure. Moreover, no differences were found between cast samples derived from the different types of manure with regards to microbial community structure, which provides strong evidence for a bottleneck effect of worm digestion on microbial populations of the original material consumed. Our data reveal that earthworm gut is a major shaper of microbial communities, thereby favouring the existence of a reduced but more active microbial population in the egested materials, which is of great importance to understand how biotic interactions within the decomposer food web influence on nutrient cycling.

  6. Epigeic earthworms exert a bottleneck effect on microbial communities through gut associated processes.

    Directory of Open Access Journals (Sweden)

    María Gómez-Brandón

    Full Text Available BACKGROUND: Earthworms play a critical role in organic matter decomposition because of the interactions they establish with microorganisms. The ingestion, digestion, assimilation of organic material in the gut and then casting is the first step in earthworm-microorganism interactions. The current knowledge of these direct effects is still limited for epigeic earthworm species, mainly those living in man-made environments. Here we tested whether and to what extent the earthworm Eisenia andrei is capable of altering the microbiological properties of fresh organic matter through gut associated processes; and if these direct effects are related to the earthworm diet. METHODOLOGY: To address these questions we determined the microbial community structure (phospholipid fatty acid profiles and microbial activity (fluorescein diacetate hydrolysis in the earthworm casts derived from three types of animal manure (cow, horse and pig manure, which differed in microbial composition. PRINCIPAL FINDINGS: The passage of the organic material through the gut of E. andrei reduced the total microbial biomass irrespective of the type of manure, and resulted in a decrease in bacterial biomass in all the manures; whilst leaving the fungi unaffected in the egested materials. However, unlike the microbial biomass, no such reduction was detected in the total microbial activity of cast samples derived from the pig manure. Moreover, no differences were found between cast samples derived from the different types of manure with regards to microbial community structure, which provides strong evidence for a bottleneck effect of worm digestion on microbial populations of the original material consumed. CONCLUSIONS/SIGNIFICANCE: Our data reveal that earthworm gut is a major shaper of microbial communities, thereby favouring the existence of a reduced but more active microbial population in the egested materials, which is of great importance to understand how biotic interactions

  7. Redox zone II. Coupled modeling of groundwater flow, solute transport, chemical reactions and microbial processes in the Aespoe island

    Energy Technology Data Exchange (ETDEWEB)

    Samper, Javier; Molinero, Jorge; Changbing Yang; Guoxiang Zhang [Univ. Da Coruna (Spain)

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behaviour and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by Banwart et al. Later, Banwart presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by Molinero who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulphate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of Molinero and extends the preliminary microbial model of Zhang by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfaphe concentration, thus adding additional evidence for the possibility

  8. Redox zone II. Coupled modeling of groundwater flow, solute transport, chemical reactions and microbial processes in the Aespoe island

    International Nuclear Information System (INIS)

    Samper, Javier; Molinero, Jorge; Changbing Yang; Guoxiang Zhang

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behaviour and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by Banwart et al. Later, Banwart presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by Molinero who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulphate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of Molinero and extends the preliminary microbial model of Zhang by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfaphe concentration, thus adding additional evidence for the possibility

  9. Coupled modeling of groundwater flow solute transport, chemical reactions and microbial processes in the 'SP' island

    Energy Technology Data Exchange (ETDEWEB)

    Samper, Javier; Molinero, Jorg; Changbing, Yang; Zhang, Guoxiang

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behavior and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by /Banwart et al, 1995/. Later, /Banwart et al, 1999/ presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by /Molinero, 2000/ who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulfate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of /Molinero, 2000/ and extends the preliminary microbial model of /Zhang, 2001/ by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfate concentration, thus

  10. Modelling coupled microbial processes in the subsurface: Model development, verification, evaluation and application

    Science.gov (United States)

    Masum, Shakil A.; Thomas, Hywel R.

    2018-06-01

    To study subsurface microbial processes, a coupled model which has been developed within a Thermal-Hydraulic-Chemical-Mechanical (THCM) framework is presented. The work presented here, focuses on microbial transport, growth and decay mechanisms under the influence of multiphase flow and bio-geochemical reactions. In this paper, theoretical formulations and numerical implementations of the microbial model are presented. The model has been verified and also evaluated against relevant experimental results. Simulated results show that the microbial processes have been accurately implemented and their impacts on porous media properties can be predicted either qualitatively or quantitatively or both. The model has been applied to investigate biofilm growth in a sandstone core that is subjected to a two-phase flow and variable pH conditions. The results indicate that biofilm growth (if not limited by substrates) in a multiphase system largely depends on the hydraulic properties of the medium. When the change in porewater pH which occurred due to dissolution of carbon dioxide gas is considered, growth processes are affected. For the given parameter regime, it has been shown that the net biofilm growth is favoured by higher pH; whilst the processes are considerably retarded at lower pH values. The capabilities of the model to predict microbial respiration in a fully coupled multiphase flow condition and microbial fermentation leading to production of a gas phase are also demonstrated.

  11. Microbial production of branched-chain dicarboxylate 2-methylsuccinic acid via enoate reductase-mediated bioreduction.

    Science.gov (United States)

    Wang, Jian; Yang, Yaping; Zhang, Ruihua; Shen, Xiaolin; Chen, Zhenya; Wang, Jia; Yuan, Qipeng; Yan, Yajun

    2018-01-01

    2-Methylsuccinic acid (2-MSA) is a C5 branched-chain dicarboxylate that serves as an attractive synthon for the synthesis of polymers with extensive applications in coatings, cosmetic solvents and bioplastics. However, the lack of natural pathways for 2-MSA biosynthesis has limited its application as a promising bio-replacement. Herein, we conceived a non-natural three-step biosynthetic route for 2-MSA, via employing the citramalate pathway in combination with enoate reductase-mediated bioreduction of the pathway intermediate citraconate. First, over-expression of codon-optimized citramalate synthase variant CimA* from Methanococcus jannaschii, endogenous isopropylmalate isomerase EcLeuCD and enoate reductase YqjM from Bacillus subtilis allowed the production of 2-MSA in Escherichia coli for the first time, with a titer of 0.35g/L in shake flask experiments. Subsequent screening of YqjM-like enoate reductases of different bacterial origins enabled identification and characterization of a new NAD(P)H-dependent enoate reductase KpnER from Klebsiella pneumoniae, which exhibited higher activity towards citraconate than YqjM. Incorporation of KpnER into the 2-MSA biosynthetic pathway led to 2-MSA production improvement to a titer of 0.96g/L in aerobic condition. Subsequent optimizations including cofactor regeneration, microaerobic cultivation and host strain engineering, boosted 2-MSA titer to 3.61g/L with a molar yield of 0.36 in shake flask experiments. This work established a promising platform for 2-MSA bioproduction, which enabled the highest titer of 2-MSA production in microbial hosts so far. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  12. Polycation-mediated integrated cell death processes

    DEFF Research Database (Denmark)

    Parhamifar, Ladan; Andersen, Helene; Wu, Linping

    2014-01-01

    standard. PEIs are highly efficient transfectants, but depending on their architecture and size they induce cytotoxicity through different modes of cell death pathways. Here, we briefly review dynamic and integrated cell death processes and pathways, and discuss considerations in cell death assay design...

  13. Intelligent query processing for semantic mediation of information systems

    Directory of Open Access Journals (Sweden)

    Saber Benharzallah

    2011-11-01

    Full Text Available We propose an intelligent and an efficient query processing approach for semantic mediation of information systems. We propose also a generic multi agent architecture that supports our approach. Our approach focuses on the exploitation of intelligent agents for query reformulation and the use of a new technology for the semantic representation. The algorithm is self-adapted to the changes of the environment, offers a wide aptitude and solves the various data conflicts in a dynamic way; it also reformulates the query using the schema mediation method for the discovered systems and the context mediation for the other systems.

  14. Nutrient limitation and microbially mediated chemistry: studies using tuff inoculum obtained from the Exploratory Studies Facility, Yucca Mountain

    International Nuclear Information System (INIS)

    Chen, C. I.; Chuu, Y. J.; Meike, A.; Ringelberg, D.; Sawvel, A.

    1998-01-01

    Flow-through bioreactors are used to investigate the relationship between the supply (and limitation) of major nutrients required by microorganisms (C, N, P, S) and effluent chemistry to obtain data that can be useful to develop models of microbially mediated aqueous chemistry. The bioreactors were inoculated with crushed tuff from Yucca Mountain. Six of the 14 bioreactor experiments currently in operation have shown growth, which occurred in as few as 5 days and as much as a few months after initiation of the experiment. All of the bioreactors exhibiting growth contained glucose as a carbon source, but other nutritional components varied. Chemical signatures of each bioreactor were compared to each other and selected results were compared to computer simulations of the equivalent abiotic chemical reactions. At 21 C, the richest medium formulation produced a microbial community that lowered the effluent pH from 6.4 to as low as 3.9. The same medium formulation at 50 C produced no significant change in pH but caused a significant increase in Cl after a period of 200 days. Variations in concentrations of other elements, some of which appear to be periodic (Ca, Mg, etc.) also occur. Bioreactors fed with low C, N, P, S media showed growth, but had stabilized at lower cell densities. The room temperature bioreactor in this group exhibited a phospholipid fatty acid (PLFA) signature of sulfur- or iron-reducing bacteria, which produced a significant chemical signature in the effluent from that bioreactor. Growth had not been observed yet in the alkaline bioreactors, even in those containing glucose. The value of combining detailed chemical and community (e.g., ester-linked PLFA) analyses, long-duration experiments, and abiotic chemical models to distinguish chemical patterns is evident. Although all of the bioreactors contain the same initial microorganisms and mineral constituents, PLFA analysis demonstrates that both input chemistry and temperature determine the

  15. Modulation of neonatal microbial recognition: TLR-mediated innate immune responses are specifically and differentially modulated by human milk.

    Science.gov (United States)

    LeBouder, Emmanuel; Rey-Nores, Julia E; Raby, Anne-Catherine; Affolter, Michael; Vidal, Karine; Thornton, Catherine A; Labéta, Mario O

    2006-03-15

    The mechanisms controlling innate microbial recognition in the neonatal gut are still to be fully understood. We have sought specific regulatory mechanisms operating in human breast milk relating to TLR-mediated microbial recognition. In this study, we report a specific and differential modulatory effect of early samples (days 1-5) of breast milk on ligand-induced cell stimulation via TLRs. Although a negative modulation was exerted on TLR2 and TLR3-mediated responses, those via TLR4 and TLR5 were enhanced. This effect was observed in human adult and fetal intestinal epithelial cell lines, monocytes, dendritic cells, and PBMC as well as neonatal blood. In the latter case, milk compensated for the low capacity of neonatal plasma to support responses to LPS. Cell stimulation via the IL-1R or TNFR was not modulated by milk. This, together with the differential effect on TLR activation, suggested that the primary effect of milk is exerted upstream of signaling proximal to TLR ligand recognition. The analysis of TLR4-mediated gene expression, used as a model system, showed that milk modulated TLR-related genes differently, including those coding for signal intermediates and regulators. A proteinaceous milk component of > or =80 kDa was found to be responsible for the effect on TLR4. Notably, infant milk formulations did not reproduce the modulatory activity of breast milk. Together, these findings reveal an unrecognized function of human milk, namely, its capacity to influence neonatal microbial recognition by modulating TLR-mediated responses specifically and differentially. This in turn suggests the existence of novel mechanisms regulating TLR activation.

  16. Advances in microbial leaching processes for nickel extraction from lateritic minerals - A review

    International Nuclear Information System (INIS)

    Behra, Sunil Kumar; Mulaba-Bafubiandi, Antoine Floribert

    2015-01-01

    Lateritic nickel minerals constitute about 80% of nickel reserves in the world, but their contribution for nickel production is about 40%. The obstacles in extraction of nickel from lateritic minerals are attributed to their very complex mineralogy and low nickel content. Hence, the existing metallurgical techniques are not techno-economically feasible and environmentally sustainable for processing of such complex deposits. At this juncture, microbial mineral processing could be a benevolent approach for processing of lateritic minerals in favor of nickel extraction. The microbial mineral processing route offers many advantages over conventional metallurgical methods as the process is operated under ambient conditions and requires low energy input; thus these processes are relatively simple and environment friendly. Microbial processing of the lateritic deposits still needs improvement to make it industrially viable. Microorganisms play the pivotal role in mineral bio-processing as they catalyze the extraction of metals from minerals. So it is inevitable to explore the physiological and bio-molecular mechanisms involved in this microbe-mineral interaction. The present article offers comprehensive information about the advances in microbial processes for extraction of nickel from laterites.

  17. Advances in microbial leaching processes for nickel extraction from lateritic minerals - A review

    Energy Technology Data Exchange (ETDEWEB)

    Behra, Sunil Kumar; Mulaba-Bafubiandi, Antoine Floribert [Faculty of Engineering and the Built Environment, University of Johannesburg, (South Africa)

    2015-08-15

    Lateritic nickel minerals constitute about 80% of nickel reserves in the world, but their contribution for nickel production is about 40%. The obstacles in extraction of nickel from lateritic minerals are attributed to their very complex mineralogy and low nickel content. Hence, the existing metallurgical techniques are not techno-economically feasible and environmentally sustainable for processing of such complex deposits. At this juncture, microbial mineral processing could be a benevolent approach for processing of lateritic minerals in favor of nickel extraction. The microbial mineral processing route offers many advantages over conventional metallurgical methods as the process is operated under ambient conditions and requires low energy input; thus these processes are relatively simple and environment friendly. Microbial processing of the lateritic deposits still needs improvement to make it industrially viable. Microorganisms play the pivotal role in mineral bio-processing as they catalyze the extraction of metals from minerals. So it is inevitable to explore the physiological and bio-molecular mechanisms involved in this microbe-mineral interaction. The present article offers comprehensive information about the advances in microbial processes for extraction of nickel from laterites.

  18. Progresses in the stable isotope studies of microbial processes associated with wetland methane production

    International Nuclear Information System (INIS)

    Li Qing; Lin Guanghui

    2013-01-01

    Methane emissions from wetlands play a key role in regulating global atmospheric methane concentration, so better understanding of microbial processes for the methane emission in wetlands is critical for developing process models and reducing uncertainty in global methane emission inventory. In this review, we describe basic microbial processes for wetland methane production and then demonstrate how stable isotope fractionation and stable isotope probing can be used to investigate the mechanisms underlying different methanogenic pathways and to quantify microbial species involved in wetland methane production. When applying stable isotope technique to calculate contributions of different pathways to the total methane production in various wetlands, the technical challenge is how to determine isotopic fractionation factors for the acetate derived methane production and carbon dioxide derived methane production. Although the application of stable isotope probing techniques to study the actual functions of different microbial organisms to methane production process is significantly superior to the traditional molecular biology method, the combination of these two technologies will be crucial for direct linking of the microbial community and functional structure with the corresponding metabolic functions, and provide new ideas for future studies. (authors)

  19. Reconstructing the Genetic Potential of the Microbially-Mediated Nitrogen Cycle in a Salt Marsh Ecosystem.

    Science.gov (United States)

    Dini-Andreote, Francisco; Brossi, Maria Julia de L; van Elsas, Jan Dirk; Salles, Joana F

    2016-01-01

    Coastal ecosystems are considered buffer zones for the discharge of land-derived nutrients without accounting for potential negative side effects. Hence, there is an urgent need to better understand the ecological assembly and dynamics of the microorganisms that are involved in nitrogen (N) cycling in such systems. Here, we employed two complementary methodological approaches (i.e., shotgun metagenomics and quantitative PCR) to examine the distribution and abundance of selected microbial genes involved in N transformations. We used soil samples collected along a well-established pristine salt marsh soil chronosequence that spans over a century of ecosystem development at the island of Schiermonnikoog, The Netherlands. Across the examined soil successional stages, the structure of the populations of genes involved in N cycling processes was strongly related to (shifts in the) soil nitrogen levels (i.e., [Formula: see text], [Formula: see text]), salinity and pH (explaining 73.8% of the total variation, R (2) = 0.71). Quantification of the genes used as proxies for N fixation, nitrification and denitrification revealed clear successional signatures that corroborated the taxonomic assignments obtained by metagenomics. Notably, we found strong evidence for niche partitioning, as revealed by the abundance and distribution of marker genes for nitrification (ammonia-oxidizing bacteria and archaea) and denitrification (nitrite reductase nirK, nirS and nitrous oxide reductase nosZ clades I and II). This was supported by a distinct correlation between these genes and soil physico-chemical properties, such as soil physical structure, pH, salinity, organic matter, total N, [Formula: see text], [Formula: see text] and [Formula: see text], across four seasonal samplings. Overall, this study sheds light on the successional trajectories of microbial N cycle genes along a naturally developing salt marsh ecosystem. The data obtained serve as a foundation to guide the formulation of

  20. Mediatization

    DEFF Research Database (Denmark)

    Hjarvard, Stig

    2017-01-01

    Mediatization research shares media effects studies' ambition of answering the difficult questions with regard to whether and how media matter and influence contemporary culture and society. The two approaches nevertheless differ fundamentally in that mediatization research seeks answers...... to these general questions by distinguishing between two concepts: mediation and mediatization. The media effects tradition generally considers the effects of the media to be a result of individuals being exposed to media content, i.e. effects are seen as an outcome of mediated communication. Mediatization...... research is concerned with long-term structural changes involving media, culture, and society, i.e. the influences of the media are understood in relation to how media are implicated in social and cultural changes and how these processes come to create new conditions for human communication and interaction...

  1. Technical difficulties and solutions of direct transesterification process of microbial oil for biodiesel synthesis.

    Science.gov (United States)

    Yousuf, Abu; Khan, Maksudur Rahman; Islam, M Amirul; Wahid, Zularisam Ab; Pirozzi, Domenico

    2017-01-01

    Microbial oils are considered as alternative to vegetable oils or animal fats as biodiesel feedstock. Microalgae and oleaginous yeast are the main candidates of microbial oil producers' community. However, biodiesel synthesis from these sources is associated with high cost and process complexity. The traditional transesterification method includes several steps such as biomass drying, cell disruption, oil extraction and solvent recovery. Therefore, direct transesterification or in situ transesterification, which combines all the steps in a single reactor, has been suggested to make the process cost effective. Nevertheless, the process is not applicable for large-scale biodiesel production having some difficulties such as high water content of biomass that makes the reaction rate slower and hurdles of cell disruption makes the efficiency of oil extraction lower. Additionally, it requires high heating energy in the solvent extraction and recovery stage. To resolve these difficulties, this review suggests the application of antimicrobial peptides and high electric fields to foster the microbial cell wall disruption.

  2. Microbial surfactant mediated degradation of anthracene in aqueous phase by marine Bacillus licheniformis MTCC 5514

    Directory of Open Access Journals (Sweden)

    Sreethar Swaathy

    2014-12-01

    Full Text Available The present study emphasizes the biosurfactant mediated anthracene degradation by a marine alkaliphile Bacillus licheniformis (MTCC 5514. The isolate, MTCC 5514 degraded >95% of 300 ppm anthracene in an aqueous medium within 22 days and the degradation percentage reduced significantly when the concentration of anthracene increased to above 500 ppm. Naphthalene, naphthalene 2-methyl, phthalic acid and benzene acetic acid are the products of degradation identified based on thin layer chromatography, high performance liquid chromatography, gas chromatography and mass analyses. It has been observed that the degradation is initiated by the biosurfactant of the isolate for solubilization through micellation and then the alkali pH and intra/extra cellular degradative enzymes accomplish the degradation process. Encoding of genes responsible for biosurfactant production (licA3 as well as catabolic reactions (C23O made with suitable primers designed. The study concludes in situ production of biosurfactant mediates the degradation of anthracene by B. licheniformis.

  3. Biogeochemical Processes Controlling Microbial Reductive Precipitation of Radionuclides

    International Nuclear Information System (INIS)

    Fredrickson, James K.; Brooks, Scott C.

    2004-01-01

    This project is focused on elucidating the principal biogeochemical reactions that govern the concentrations, chemical speciation, and distribution of the redox sensitive contaminants uranium (U) and technetium (Tc) between the aqueous and solid phases. The research is designed to provide new insights into the under-explored areas of competing geochemical and microbiological oxidation-reduction reactions that govern the fate and transport of redox sensitive contaminants and to generate fundamental scientific understanding of the identity and stoichiometry of competing microbial reduction and geochemical oxidation reactions. These goals and objectives are met through a series of hypothesis-driven tasks that focus on (1) the use of well-characterized microorganisms and synthetic and natural mineral oxidants, (2) advanced spectroscopic and microscopic techniques to monitor redox transformations of U and Tc, and (3) the use of flow-through experiments to more closely approximate groundwater environments. The results are providing an improved understanding and predictive capability of the mechanisms that govern the redox dynamics of radionuclides in subsurface environments. For purposes of this poster, the results are divided into three sections: (1) influence of Ca on U(VI) bioreduction; (2) localization of biogenic UO 2 and TcO 2 ; and (3) reactivity of Mn(III/IV) oxides.

  4. Development and application of microbial selective plugging processes

    Energy Technology Data Exchange (ETDEWEB)

    Jenneman, G.E. [Phillips Petroleum Co., Bartlesville, OK (United States); Gevertz, D.; Davey, M.E. [Agouron Institute, La Jolla, CA (United States)] [and others

    1995-12-31

    Phillips Petroleum Company recently completed a microbial selective plugging (MSP) pilot at the North Burbank Unit (NBU), Shidler, Oklahoma. Nutrients were selected for the pilot that could stimulate indigenous microflora in the reservoir brine to grow and produce exopolymer. It was found that soluble corn starch polymers (e.g., maltodextrins) stimulated the indigenous bacteria to produce exopolymer, whereas simple sugars (e.g., glucose and sucrose), as well as complex media (e.g., molasses and Nutrient Broth), did not. Injection of maltodextrin into rock cores in the presence of indigenous NBU bacteria resulted in stable permeability reductions (> 90%) across the entire length, while injection of glucose resulted only in face plugging. In addition, it was found that organic phosphate esters (OPE) served as a preferable source of phosphorus for the indigenous bacteria, since orthophosphates and condensed phosphates precipitated in NBU brine at reservoir temperature (45{degrees}C). Injection of maltodextrin and ethyl acid phosphate into a producing well stimulated an increase in maltodextrin utilizing bacteria (MUB) in the back-flowed, produced fluid. Additional screens of indigenous and nonindigenous bacteria yielded several nonindigenous isolates that could synthesize polymer when growing in brine containing 6% NaCl at 45{degrees}C.

  5. Integrated hydrogen production process from cellulose by combining dark fermentation, microbial fuel cells, and a microbial electrolysis cell

    KAUST Repository

    Wang, Aijie

    2011-03-01

    Hydrogen gas production from cellulose was investigated using an integrated hydrogen production process consisting of a dark fermentation reactor and microbial fuel cells (MFCs) as power sources for a microbial electrolysis cell (MEC). Two MFCs (each 25mL) connected in series to an MEC (72mL) produced a maximum of 0.43V using fermentation effluent as a feed, achieving a hydrogen production rate from the MEC of 0.48m 3 H 2/m 3/d (based on the MEC volume), and a yield of 33.2mmol H 2/g COD removed in the MEC. The overall hydrogen production for the integrated system (fermentation, MFC and MEC) was increased by 41% compared with fermentation alone to 14.3mmol H 2/g cellulose, with a total hydrogen production rate of 0.24m 3 H 2/m 3/d and an overall energy recovery efficiency of 23% (based on cellulose removed) without the need for any external electrical energy input. © 2010 Elsevier Ltd.

  6. Integrated hydrogen production process from cellulose by combining dark fermentation, microbial fuel cells, and a microbial electrolysis cell.

    Science.gov (United States)

    Wang, Aijie; Sun, Dan; Cao, Guangli; Wang, Haoyu; Ren, Nanqi; Wu, Wei-Min; Logan, Bruce E

    2011-03-01

    Hydrogen gas production from cellulose was investigated using an integrated hydrogen production process consisting of a dark fermentation reactor and microbial fuel cells (MFCs) as power sources for a microbial electrolysis cell (MEC). Two MFCs (each 25 mL) connected in series to an MEC (72 mL) produced a maximum of 0.43 V using fermentation effluent as a feed, achieving a hydrogen production rate from the MEC of 0.48 m(3) H(2)/m(3)/d (based on the MEC volume), and a yield of 33.2 mmol H(2)/g COD removed in the MEC. The overall hydrogen production for the integrated system (fermentation, MFC and MEC) was increased by 41% compared with fermentation alone to 14.3 mmol H(2)/g cellulose, with a total hydrogen production rate of 0.24 m(3) H(2)/m(3)/d and an overall energy recovery efficiency of 23% (based on cellulose removed) without the need for any external electrical energy input. Copyright © 2010 Elsevier Ltd. All rights reserved.

  7. Process Mediation, Execution Monitoring and Recovery for Semantic Web Services

    Czech Academy of Sciences Publication Activity Database

    Sycara, K.; Vaculín, Roman

    2008-01-01

    Roč. 31, č. 3 (2008), s. 14-18 ISSN N R&D Projects: GA ČR(CZ) GD201/05/H014; GA MŠk ME08095 Institutional research plan: CEZ:AV0Z10300504 Keywords : process mediation of semantic web services * semantic web services * OWL-S Subject RIV: IN - Informatics, Computer Science

  8. The Process Mediation Framework for Semantic Web Services

    Czech Academy of Sciences Publication Activity Database

    Vaculín, Roman; Neruda, Roman

    2009-01-01

    Roč. 3, č. 1 (2009), s. 27-58 ISSN 1746-1375 R&D Projects: GA MŠk ME08095; GA AV ČR 1ET100300517 Institutional research plan: CEZ:AV0Z10300504 Keywords : process mediation * OWL-S * semantic web services * adapter synthesis Subject RIV: IN - Informatics, Computer Science

  9. Trust, Knowledge Creation and Mediating Effects of Knowledge Transfer Processes

    Directory of Open Access Journals (Sweden)

    Anna Sankowska

    2016-01-01

    Full Text Available This paper investigates how organizational trust contributes to knowledge transfer processes and knowledge creation both directly and indirectly. The mediation analyses were used. The findings using cross-sectional data from Polish companies suggest a new way of thinking in respect of how crucial is trust to creation of knowledge unconnected to organizational memory.

  10. Microbial processes in the Kanda Bay, a meromictic water body artifically separated from the White Sea.

    Science.gov (United States)

    Savvichev, A S; Demidenko, N A; Krasnova, E D; Kalmatskaya, O V; Kharcheva, A N; Ivanov, M V

    2017-05-01

    Sings of meromixis are found by means of microbiological and biogeochemical investigations in the southernn part of the Kanda Bay, an artificial water body separated front the White Sea with a railway dam. The concentration of oxygen in the bottom layer attained 1.9 mmol/L, intensity of the process of microbial sulfate reduction, 3.0 μmol of sulfur/(L day). The concentration of dissolved methane, 3.7 μmol/L. Isotopic composition of carbon in methane (δ 13 C (CH 4 ) =-79.2‰) indicates to its microbial genesis. At present, Kanda Bay is a sole in Russia man-made marine water body for which there are data on the rate of microbial processes responsible for formation of bottom water layer containing hydrogen sulfide and methane.

  11. The porous surface model, a novel experimental system for online quantitative observation of microbial processes under unsaturated conditions

    DEFF Research Database (Denmark)

    Dechesne, Arnaud; Or, D.; Gulez, Gamze

    2008-01-01

    Water is arguably the most important constituent of microbial microhabitats due to its control of physical and physiological processes critical to microbial activity. In natural environments, bacteria often live on unsaturated surfaces, in thin (micrometric) liquid films. Nevertheless, no experim....... The PSM constitutes a tool uniquely adapted to study the influence of liquid film geometry on microbial processes. It should therefore contribute to uncovering mechanisms of microbial adaptation to unsaturated environments.......Water is arguably the most important constituent of microbial microhabitats due to its control of physical and physiological processes critical to microbial activity. In natural environments, bacteria often live on unsaturated surfaces, in thin (micrometric) liquid films. Nevertheless......, no experimental systems are available that allow real-time observation of bacterial processes in liquid films of controlled thickness. We propose a novel, inexpensive, easily operated experimental platform, termed the porous surface model (PSM) that enables quantitative real-time microscopic observations...

  12. The response of soil carbon storage and microbially mediated carbon turnover to simulated climatic disturbance in a northern peatland forest. Revisiting the concept of soil organic matter recalcitrance

    Energy Technology Data Exchange (ETDEWEB)

    Kostka, Joel [Georgia Inst. of Technology, Atlanta, GA (United States)

    2015-09-14

    The goal of this project was to investigate changes in the structure of dissolved and solid phase organic matter, the production of CO2 and CH4, and the composition of decomposer microbial communities in response to the climatic forcing of environmental processes that determine the balance between carbon gas production versus storage and sequestration in peatlands. Cutting-edge analytical chemistry and next generation sequencing of microbial genes were been applied to habitats at the Marcell Experimental Forest (MEF), where the US DOE’s Oak Ridge National Laboratory and the USDA Forest Service are constructing a large-scale ecosystem study entitled, “Spruce and Peatland Responses Under Climatic and Environmental Change”(SPRUCE). Our study represented a comprehensive characterization of the sources, transformation, and decomposition of organic matter in the S1 bog at MEF. Multiple lines of evidence point to distinct, vertical zones of organic matter transformation: 1) the acrotelm consisting of living mosses, root material, and newly formed litter (0-30 cm), 2) the mesotelm, a mid-depth transition zone (30-75 cm) characterized by labile organic C compounds and intense decomposition, and 3) the underlying catotelm (below 75cm) characterized by refractory organic compounds as well as relatively low decomposition rates. These zones are in part defined by physical changes in hydraulic conductivity and water table depth. O-alkyl-C, which represents the carbohydrate fraction in the peat, was shown to be an excellent proxy for soil decomposition rates. The carbon cycle in deep peat was shown to be fueled by modern carbon sources further indicating that hydrology and surface vegetation play a role in belowground carbon cycling. We provide the first metagenomic study of an ombrotrophic peat bog, with novel insights into microbial specialization and functions in this unique terrestrial ecosystem. Vertical structuring of microbial communities

  13. Multistage A-O Activated Sludge Process for Paraformaldehyde Wastewater Treatment and Microbial Community Structure Analysis

    Directory of Open Access Journals (Sweden)

    Danyang Zheng

    2016-01-01

    Full Text Available In recent years, the effect of formaldehyde on microorganisms and body had become a global public health issue. The multistage combination of anaerobic and aerobic process was adopted to treat paraformaldehyde wastewater. Microbial community structure in different reaction stages was analyzed through high-throughput sequencing. Results showed that multistage A-O activated sludge process positively influenced polyformaldehyde wastewater. The removal rates of formaldehyde were basically stable at more than 99% and those of COD were about 89%. Analysis of the microbial diversity index indicated that the microbial diversity of the reactor was high, and the treatment effect was good. Moreover, microbial community had certain similarity in the same system. Microbial communities in different units also showed typical representative characteristics affected by working conditions and influent concentrations. Proteobacteria, Firmicutes, and Bacteroidetes were the dominant fungal genera in the phylum level of community composition. As to family and genus levels, Peptostreptococcaceae was distributed at various stages and the dominant in this system. This bacterium also played an important role in organic matter removal, particularly decomposition of the acidified middle metabolites. In addition, Rhodobacteraceae and Rhodocyclaceae were the formaldehyde-degrading bacteria found in the reactor.

  14. Good Manufacturing Practices and Microbial Contamination Sources in Orange Fleshed Sweet Potato Puree Processing Plant in Kenya

    OpenAIRE

    Malavi, Derick Nyabera; Muzhingi, Tawanda; Abong’, George Ooko

    2018-01-01

    Limited information exists on the status of hygiene and probable sources of microbial contamination in Orange Fleshed Sweet Potato (OFSP) puree processing. The current study is aimed at determining the level of compliance to Good Manufacturing Practices (GMPs), hygiene, and microbial quality in OFSP puree processing plant in Kenya. Intensive observation and interviews using a structured GMPs checklist, environmental sampling, and microbial analysis by standard microbiological methods were use...

  15. Natural attenuation process via microbial oxidation of arsenic in a high Andean watershed.

    Science.gov (United States)

    Leiva, Eduardo D; Rámila, Consuelo d P; Vargas, Ignacio T; Escauriaza, Cristian R; Bonilla, Carlos A; Pizarro, Gonzalo E; Regan, John M; Pasten, Pablo A

    2014-01-01

    Rivers in northern Chile have arsenic (As) concentrations at levels that are toxic for humans and other organisms. Microorganism-mediated redox reactions have a crucial role in the As cycle; the microbial oxidation of As (As(III) to As(V)) is a critical transformation because it favors the immobilization of As in the solid phase. We studied the role of microbial As oxidation for controlling the mobility of As in the extreme environment found in the Chilean Altiplano (i.e., > 4000 meters above sea level (masl) and Azufre River sub-basin, where the natural attenuation of As from hydrothermal discharge (pH 4-6) was observed. As(III) was actively oxidized by a microbial consortium, leading to a significant decrease in the dissolved As concentrations and a corresponding increase in the sediment's As concentration downstream of the hydrothermal source. In-situ oxidation experiments demonstrated that the As oxidation required biological activity, and microbiological molecular analysis confirmed the presence of As(III)-oxidizing groups (aroA-like genes) in the system. In addition, the pH measurements and solid phase analysis strongly suggested that the As removal mechanism involved adsorption or coprecipitation with Fe-oxyhydroxides. Taken together, these results indicate that the microorganism-mediated As oxidation contributed to the attenuation of As concentrations and the stabilization of As in the solid phase, therefore controlling the amount of As transported downstream. This study is the first to demonstrate the microbial oxidation of As in Altiplano basins and its relevance in the immobilization of As. © 2013.

  16. Microbial and preservative safety of fresh and processed fruit salads ...

    African Journals Online (AJOL)

    The producers and traders of fresh fruit and the processers should implement quality management practices and safety standards in farming, fresh fruit, processing and storage. This is to ensure safety, enhance consumption of fruits and fruit products for health of consumers and eliminate wastage. Key words: Fresh fruit, ...

  17. Quantification of microbial quality and safety in minimally processed foods

    NARCIS (Netherlands)

    Zwietering, M.H.

    2002-01-01

    To find a good equilibrium between quality and margin of safety of minimally processed foods, often various hurdles are used. Quantification of the kinetics should be used to approach an optimum processing and to select the main aspects. Due to many factors of which the exact quantitative effect is

  18. Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases.

    Science.gov (United States)

    Welch, David; Buonanno, Manuela; Grilj, Veljko; Shuryak, Igor; Crickmore, Connor; Bigelow, Alan W; Randers-Pehrson, Gerhard; Johnson, Gary W; Brenner, David J

    2018-02-09

    Airborne-mediated microbial diseases such as influenza and tuberculosis represent major public health challenges. A direct approach to prevent airborne transmission is inactivation of airborne pathogens, and the airborne antimicrobial potential of UVC ultraviolet light has long been established; however, its widespread use in public settings is limited because conventional UVC light sources are both carcinogenic and cataractogenic. By contrast, we have previously shown that far-UVC light (207-222 nm) efficiently inactivates bacteria without harm to exposed mammalian skin. This is because, due to its strong absorbance in biological materials, far-UVC light cannot penetrate even the outer (non living) layers of human skin or eye; however, because bacteria and viruses are of micrometer or smaller dimensions, far-UVC can penetrate and inactivate them. We show for the first time that far-UVC efficiently inactivates airborne aerosolized viruses, with a very low dose of 2 mJ/cm 2 of 222-nm light inactivating >95% of aerosolized H1N1 influenza virus. Continuous very low dose-rate far-UVC light in indoor public locations is a promising, safe and inexpensive tool to reduce the spread of airborne-mediated microbial diseases.

  19. Stable, geochemically mediated biospheres in the Deep Mine Microbial Observatory, SD, USA

    Science.gov (United States)

    Osburn, M. R.; Casar, C. P.; Kruger, B.; Flynn, T. M.

    2017-12-01

    The terrestrial subsurface is a vast reservoir of life, hosting diverse microbial ecosystems with varying levels of connectivity to surface inputs. Understanding long term ecosystem dynamics within the subsurface biosphere is very challenging due to limitations in accessibility, sample availability, and slow microbial growth rates. The establishment of the Deep Mine Microbial Observatory (DeMMO) at the Sanford Underground Research Facility, SD, USA has allowed for bimonthly sampling for nearly two years at six sites spanning 250 to 1500 m below the surface. Here we present a time-resolved analysis of the geomicrobiology of the six DeMMO sites, which have been created from legacy mine boreholes modified to allow for controlled sampling. Our interdisciplinary approach includes analysis of passively draining fracture fluid for aqueous and gas geochemistry, DNA sequencing, microscopy, and isotopic measurements of organic and inorganic substrates. Fluid geochemistry varies significantly between sites, but is relatively stable over time for a given site, even through significant external perturbations such as drilling and installation of permanent sampling devices into the boreholes. The fluid-hosted microbial diversity follows these trends, with consistent populations present at each site through time, even through drilling events. For instance, the shallowest site (DeMMO 1) consistently hosts >30% uncharacterized phyla and >25% Omnitrophica whereas the deepest site (DeMMO 6) is dominated by Firmicutes and Bacterioidetes. Microbial diversity appears to respond to the availability of energy sources such as organic carbon, sulfate, sulfide, hydrogen, and iron. Carbon isotopic measurements reveal closed system behavior with significant recycling of organic carbon into the DIC pool. Together these observations suggest DeMMO hosts isolated subsurface microbial populations adapted to local geochemistry that are stable on yearlong timescales.

  20. Optimization of process variables for the microbial degradation of ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-07-18

    Jul 18, 2008 ... The optimum process conditions for maximizing phenol degradation (removal) ... cellular maintenance requirements on temperature makes it an important ..... the International Foundation for Science (IFS) for the financial ...

  1. Side Effects of Nitrification Inhibitors on Non Target Microbial Processes in Soils

    Directory of Open Access Journals (Sweden)

    Johannes Carl Gottlieb Ottow

    2011-01-01

    Full Text Available Agricultural chemicals have been used extensively in modern agriculture and toxicological studies suggest a great potential for inducing undesirable effects on non target organisms. A model experiment was conducted in order to determine side effects of three nitrification inhibitors (NIs, 3,4dimethylpyrazolephosphate = DMPP, 4-Chlor-methylpyrazole phosphate = ClMPP and dicyandiamide = DCD on non target microbial processes in soils. Side effects and dose response curve of three NIs were quantified under laboratory conditions using silty clay, loam and a sandy soils. Dehydrogenase, dimethylsulfoxide reductase as well as nitrogenase activity (NA and potential denitrification capacity were measured as common and specific non target microbial processes. The influence of 5-1000 times the base concentration, dose response curves were examined, and no observable effect level = NOEL, as well as effective dose ED10 and ED50 (10% and 50% inhibition were calculated. The NOEL for microbial non target processes were about 30–70 times higher than base concentration in all investigated soils. The potential denitrification capacity revealed to be the most sensitive parameter. ClMPP exhibited the strongest influence on the non target microbial processes in the three soils. The NOEL, ED10 and ED50 values were higher in clay than in loamy or sandy soil. The NIs was the most effective in sandy soils.

  2. Effects of post-processing handling and packaging on microbial populations

    International Nuclear Information System (INIS)

    Zagory, D.

    1999-01-01

    The type of produce, process conditions, and prior temperature management will all affect the mix of microorganisms found on fresh produce. Normally, fresh produce will be covered by a complex mix of bacteria, fungi and yeasts that are characteristic of that fruit or vegetable. For example, carrots typically have large numbers of Lactobacillus and other lactic acid bacteria while apples may have relatively large numbers of yeasts. Which of these microorganisms will come to dominate the population will be a function of the make-up of the original population on the product in the field, distribution time, distribution temperature and the atmosphere within the package. Another chief determinant of microbial populations will be the physiological condition of the product. Factors that injure or weaken the plant tissues may be expected to encourage microbial growth while conditions that maintain the physiological integrity of the tissues may be expected to discourage microbial growth. Each of these factors can be expected to affect the make-up of the microbial population in characteristic ways but always constrained by the initial condition of original population makeup. This paper describes which microorganisms are favored by given conditions in order to develop a concept of microbial management designed to favor desirable microbes at the expense of undesirable ones. Particular emphasis will be placed on the effects of modified atmospheres on microorganisms, especially human pathogens

  3. Microbial Communities: Tracing Growth Processes from Antarctic Lakes to Early Earth to Other Planets

    Science.gov (United States)

    Sumner, D. Y.

    2014-12-01

    Life in the Universe is dominated by microbes: they are numerically the most abundant cells in our bodies and in Earth's biosphere, and they are the only life that might be present elsewhere in our solar system. Life beyond our solar system could include macroscopic organisms, but everything we understand about the origin of life suggests it must start with microbes. Thus, understanding microbial ecosystems, in the absence of macroscopic organisms, is critical to understanding early life on Earth and life elsewhere in the Universe - if it exists. But what are the general principles of microbial ecology in the absence of predation? What happens when each cell is a chemical factory that can swap among metabolic processes in response to environmental and emergent cues? Geobiologists and astrobiologists are addressing these questions in diverse ways using both Earth's modern biosphere and its fossil record. Modern microbial communities in shallow, ice-covered lakes, Antarctica (Fig.), provide a model for high productivity microbial ecosystems with no to low predation. In these lakes, photosynthetic communities create macroscopic pinnacles and domes, sometime lithified into stromatolites. They provide an ecological, geochemical and morphological model for Precambrian microbial communities in low sedimentation, low current environments. Insights from these communities include new growth processes for ancient mats, especially some that grew prior to the oxidation of Earth's atmosphere. The diversity of biosignatures created in these communities also provides context for models of life under ice elsewhere in our solar system such as paleolakes on Mars and on icy moons. Results from the Mars Science Laboratory (MSL) team document formerly habitable fluvial and lacustrine environments. Lacustrine environments, in particular, are favorable for preserving biosignatures, and continued investigations by MSL will provide a deeper understanding of the duration of habitable

  4. Comparison of microbial community shifts in two parallel multi-step drinking water treatment processes.

    Science.gov (United States)

    Xu, Jiajiong; Tang, Wei; Ma, Jun; Wang, Hong

    2017-07-01

    Drinking water treatment processes remove undesirable chemicals and microorganisms from source water, which is vital to public health protection. The purpose of this study was to investigate the effects of treatment processes and configuration on the microbiome by comparing microbial community shifts in two series of different treatment processes operated in parallel within a full-scale drinking water treatment plant (DWTP) in Southeast China. Illumina sequencing of 16S rRNA genes of water samples demonstrated little effect of coagulation/sedimentation and pre-oxidation steps on bacterial communities, in contrast to dramatic and concurrent microbial community shifts during ozonation, granular activated carbon treatment, sand filtration, and disinfection for both series. A large number of unique operational taxonomic units (OTUs) at these four treatment steps further illustrated their strong shaping power towards the drinking water microbial communities. Interestingly, multidimensional scaling analysis revealed tight clustering of biofilm samples collected from different treatment steps, with Nitrospira, the nitrite-oxidizing bacteria, noted at higher relative abundances in biofilm compared to water samples. Overall, this study provides a snapshot of step-to-step microbial evolvement in multi-step drinking water treatment systems, and the results provide insight to control and manipulation of the drinking water microbiome via optimization of DWTP design and operation.

  5. Bacterially mediated mineralisation processes lead to biodeterioration of artworks in Maltese catacombs

    International Nuclear Information System (INIS)

    Zammit, Gabrielle; Sanchez-Moral, Sergio; Albertano, Patrizia

    2011-01-01

    Mineral structures formed by bacterial and microalgal biofilms growing on the archaeological surface in Maltese hypogea were studied using Energy Dispersive X-Ray Spectroscopy (EDS) coupled to Environmental Scanning Electron Microscopy (ESEM), X-ray micro-diffraction (XRD) and X-ray fluorescence (XRF). These techniques have shown that mineral structures having different morphologies and chemical composition were associated with the microorganisms in the subaerophytic biofilm. Salt efflorescences and mineral deposits on the archaeological surface were often formed from gypsum (CaSO 4 · 2H 2 O), halite (NaCl) and calcite (CaCO 3 ). Biogenic carbonates produced by microbial activities were a common occurrence. These assumed different forms, such as the production of mineral coats around cyanobacterial sheaths and the occurrence of calcite fibres with different morphologies on the surface of the biofilms. Moreover, vaterite (CaCO 3 ) spherulites which appeared hollow in cross-section were observed. The presence of struvite was recorded from one catacomb site. These investigations have facilitated the study of the neoformation of metastable minerals by microbially mediated processes, which potentially contribute to a better understanding of the biodeterioration of artworks in Maltese palaeo-Christian catacombs. - Research highlights: → Mineral structures formed by subaerial biofilms growing in hypogea were examined. → Efflorescences and mineral deposits were often formed from gypsum, halite, and calcite. → Biogenic carbonates assumed different forms e.g. vaterite spherulite, calcite fibres. → The formation of rare minerals e.g. struvite was mediated by bacteria. → Understanding biomineralisation processes facilitates the conservation of artworks.

  6. Bacterially mediated mineralisation processes lead to biodeterioration of artworks in Maltese catacombs

    Energy Technology Data Exchange (ETDEWEB)

    Zammit, Gabrielle, E-mail: gabrielle.zammit@gmail.com [Dept. of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta (Malta); Sanchez-Moral, Sergio [Dept. de Geologia, Museo Nacional de Ciencias Naturales, CSIC, Madrid (Spain); Albertano, Patrizia [Dept. of Biology, Faculty of Science, University of Rome ' Tor Vergata' , Rome (Italy)

    2011-06-15

    Mineral structures formed by bacterial and microalgal biofilms growing on the archaeological surface in Maltese hypogea were studied using Energy Dispersive X-Ray Spectroscopy (EDS) coupled to Environmental Scanning Electron Microscopy (ESEM), X-ray micro-diffraction (XRD) and X-ray fluorescence (XRF). These techniques have shown that mineral structures having different morphologies and chemical composition were associated with the microorganisms in the subaerophytic biofilm. Salt efflorescences and mineral deposits on the archaeological surface were often formed from gypsum (CaSO{sub 4}{center_dot} 2H{sub 2}O), halite (NaCl) and calcite (CaCO{sub 3}). Biogenic carbonates produced by microbial activities were a common occurrence. These assumed different forms, such as the production of mineral coats around cyanobacterial sheaths and the occurrence of calcite fibres with different morphologies on the surface of the biofilms. Moreover, vaterite (CaCO{sub 3}) spherulites which appeared hollow in cross-section were observed. The presence of struvite was recorded from one catacomb site. These investigations have facilitated the study of the neoformation of metastable minerals by microbially mediated processes, which potentially contribute to a better understanding of the biodeterioration of artworks in Maltese palaeo-Christian catacombs. - Research highlights: {yields} Mineral structures formed by subaerial biofilms growing in hypogea were examined. {yields} Efflorescences and mineral deposits were often formed from gypsum, halite, and calcite. {yields} Biogenic carbonates assumed different forms e.g. vaterite spherulite, calcite fibres. {yields} The formation of rare minerals e.g. struvite was mediated by bacteria. {yields} Understanding biomineralisation processes facilitates the conservation of artworks.

  7. Long-term high-solids anaerobic digestion of food waste: Effects of ammonia on process performance and microbial community.

    Science.gov (United States)

    Peng, Xuya; Zhang, ShangYi; Li, Lei; Zhao, Xiaofei; Ma, Yao; Shi, Dezhi

    2018-04-22

    A long-term high solids anaerobic digestion of food waste was conducted to identify microbial mechanisms of ammonia inhibition during digestion and to clarify correlations between ammonia accumulation, microbial community dynamics (diversity, composition, and interactions), and process stability. Results show that the effects of ammonia on process performance and microbial community were indirectly caused by volatile fatty acid accumulation. Excess free ammonia blocked acetate metabolism, leading to process instability. Accumulated acetate caused feedback inhibition at the acetogenesis stage, which resulted in considerable accumulation of propionate, valerate, and other long-chain fatty acids. This high concentration of volatile fatty acids reduced the abundance of syntrophic acetogenic bacteria and allowed hydrolytic fermentative bacteria to dominate. The normally interactive and orderly metabolic network was broken, which further exacerbated the process instability. These results improve the understanding of microbial mechanisms which contribute to process instability and provide guidance for the microbial management of anaerobic digesters. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Complex media from processing of agricultural crops for microbial fermentation

    DEFF Research Database (Denmark)

    Thomsen, M.H.

    2005-01-01

    , is converted to a basic, universal fermentation medium by lactic acid fermentation, is outlined. The resulting all-round fermentation medium can be used for the production of many useful fermentation products when added a carbohydrate source, which could possibly be another agricultural by-product. Two...... examples of such products-polylactic acid and L-lysine-are given. A cost calculation shows that this fermentation medium can be produced at a very low cost approximate to 1.7 Euro cent/kg, when taking into account that the green crop industry has expenses amounting to 270,000 Euro/year for disposal...... of the brown juice. A newly built lysine factory in Esbjerg, Denmark, can benefit from this process by buying a low price medium for the fermentation process instead of more expensive traditional fermentation liquids such as corn steep liquor....

  9. Safety conditions and native microbial flora of three processing units in Alentejo , Portugal

    OpenAIRE

    Laranjo, Marta; Potes, M.E; Elias, M.

    2014-01-01

    Portugal as other Mediterranean countries has a great diversity of dry fermented sausages. This traditional sausage production is highly diverse and products possess very particular organoleptic characteristics, which please consumers. These sensory characteristics are related not only to the manufacturing process, but also to the house microbial flora. On the other hand, the safety of fermented products is always difficult to achieve due to their processing technology and final characteristi...

  10. Microbial Ecology and Process Technology of Sourdough Fermentation.

    Science.gov (United States)

    De Vuyst, Luc; Van Kerrebroeck, Simon; Leroy, Frédéric

    2017-01-01

    From a microbiological perspective, sourdough is to be considered as a specific and stressful ecosystem, harboring yeasts and lactic acid bacteria (LAB), that is used for the production of baked goods. With respect to the metabolic impact of the sourdough microbiota, acidification (LAB), flavor formation (LAB and yeasts), and leavening (yeasts and heterofermentative LAB species) are most noticeable. Three distinct types of sourdough fermentation processes can be discerned based on the inocula applied, namely backslopped ones (type 1), those initiated with starter cultures (type 2), and those initiated with a starter culture followed by backslopping (type 3). A sourdough-characteristic LAB species is Lactobacillus sanfranciscensis. A sourdough-characteristic yeast species is Candida humilis. Although it has been suggested that the microbiota of a specific sourdough may be influenced by its geographical origin, region specificity often seems to be an artefact resulting from interpretation of the research data, as those are dependent on sampling, isolation, and identification procedures. It is however clear that sourdough-adapted microorganisms are able to withstand stress conditions encountered during their growth. Based on the technological setup, type 0 (predoughs), type I (artisan bakery firm sourdoughs), type II (industrial liquid sourdoughs), and type III sourdoughs (industrial dried sourdoughs) can be distinguished. The production of all sourdoughs, independent of their classification, depends on several intrinsic and extrinsic factors. Both the flour (type, quality status, etc.) and the process parameters (fermentation temperature, pH and pH evolution, dough yield, water activity, oxygen tension, backslopping procedure and fermentation duration, etc.) determine the dynamics and outcome of (backslopped) sourdough fermentation processes. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Chirality in microbial biofilms is mediated by close interactions between the cell surface and the substratum

    Science.gov (United States)

    Jauffred, Liselotte; Munk Vejborg, Rebecca; Korolev, Kirill S; Brown, Stanley; Oddershede, Lene B

    2017-01-01

    From microbial biofilms to human migrations, spatial competition is central to the evolutionary history of many species. The boundary between expanding populations is the focal point of competition for space and resources and is of particular interest in ecology. For all Escherichia coli strains studied here, these boundaries move in a counterclockwise direction even when the competing strains have the same fitness. We find that chiral growth of bacterial colonies is strongly suppressed by the expression of extracellular features such as adhesive structures and pili. Experiments with other microbial species show that chiral growth is found in other bacteria and exclude cell wall biosynthesis and anisotropic shape as the primary causes of chirality. Instead, intimate contact with the substratum is necessary for chirality. Our results demonstrate that through a handful of surface molecules cells can fundamentally reorganize their migration patterns, which might affect intra- and interspecific competitions through colony morphology or other mechanisms. PMID:28362723

  12. Study of the diversity of microbial communities in a sequencing batch reactor oxic-settling-anaerobic process and its modified process.

    Science.gov (United States)

    Sun, Lianpeng; Chen, Jianfan; Wei, Xiange; Guo, Wuzhen; Lin, Meishan; Yu, Xiaoyu

    2016-05-01

    To further reveal the mechanism of sludge reduction in the oxic-settling-anaerobic (OSA) process, the polymerase chain reaction - denaturing gradient gel electrophoresis protocol was used to study the possible difference in the microbial communities between a sequencing batch reactor (SBR)-OSA process and its modified process, by analyzing the change in the diversity of the microbial communities in each reactor of both systems. The results indicated that the structure of the microbial communities in aerobic reactors of the 2 processes was very different, but the predominant microbial populations in anaerobic reactors were similar. The predominant microbial population in the aerobic reactor of the SBR-OSA belonged to Burkholderia cepacia, class Betaproteobacteria, while those of the modified process belonged to the classes Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria. These 3 types of microbes had a cryptic growth characteristic, which was the main cause of a greater sludge reduction efficiency achieved by the modified process.

  13. Organic priority substances and microbial processes in river sediments subject to contrasting hydrological conditions.

    Science.gov (United States)

    Zoppini, Annamaria; Ademollo, Nicoletta; Amalfitano, Stefano; Casella, Patrizia; Patrolecco, Luisa; Polesello, Stefano

    2014-06-15

    Flood and drought events of higher intensity and frequency are expected to increase in arid and semi-arid regions, in which temporary rivers represent both a water resource and an aquatic ecosystem to be preserved. In this study, we explored the variation of two classes of hazardous substances (Polycyclic Aromatic Hydrocarbons and Nonylphenols) and the functioning of the microbial community in river sediments subject to hydrological fluctuations (Candelaro river basin, Italy). Overall, the concentration of pollutants (∑PAHs range 8-275ngg(-1); ∑NPs range 299-4858ngg(-1)) suggests a moderate degree of contamination. The conditions in which the sediments were tested, flow (high/low) and no flow (wet/dry/arid), were associated to significant differences in the chemical and microbial properties. The total organic carbon contribution decreased together with the stream flow reduction, while the contribution of C-PAHs and C-NPs tended to increase. NPs were relatively more concentrated in sediments under high flow, while the more hydrophobic PAHs accumulated under low and no flow conditions. Passing from high to no flow conditions, a gradual reduction of microbial processes was observed, to reach the lowest specific bacterial carbon production rates (0.06fmolCh(-1)cell(-1)), extracellular enzyme activities, and the highest doubling time (40h) in arid sediments. In conclusion, different scenarios for the mobilization of pollutants and microbial processes can be identified under contrasting hydrological conditions: (i) the mobilization of pollutants under high flow and a relatively higher probability for biodegradation; (ii) the accumulation of pollutants during low flow and lower probability for biodegradation; (iii) the drastic reduction of pollutant concentrations under dry and arid conditions, probably independently from the microbial activity (abiotic processes). Our findings let us infer that a multiple approach has to be considered for an appropriate water

  14. Downstream Processing, Formulation Development and Antithrombotic Evaluation of Microbial Nattokinase.

    Science.gov (United States)

    Kapoor, Rohit; Harde, Harshad; Jain, Sanyog; Panda, Amulya Kumar; Panda, Bibhu Prasad

    2015-07-01

    The present research work describes the downstreaming of nattokinase (NK) produced by Bacillus subtilis under solid state fermentation; and the role of efficient oral formulation of purified NK in the management of thrombotic disorders. Molecular weight of purified NK was estimated to be 28 kDa with specific activity of 504.4 FU/mg. Acid stable nattokinase loaded chitosan nanoparticles (sNLCN) were fabricated for oral delivery of this enzyme. Box-Behnken design (BBD) was employed to investigate and validate the effect of process (independent) variables on the quality attributes (dependent variables) of nanoparticles. The integrity, conformational stability and preservation of fibrinolytic activity of NK (in both free and sNLCN forms) were established by SDS-PAGE, CD analysis and in vitro clot lytic examination, respectively. A 'tail thrombosis model' demonstrated significant decrease in frequency of thrombosis in Wistar rats upon peroral administration of sNLCN in comparison with negative control and free NK group. Furthermore, coagulation analysis, namely the measurement of prothrombin and activated partial thromboplastin time illustrated that sNLCN showed significantly (p < 0.001) higher anti-thrombotic potential in comparison to the free NK. Further, sNLCN showed anti-thrombotic profile similar to warfarin. This study signifies the potential of sNLCN in oral delivery of NK for the management of thrombotic disorders.

  15. Relationships between processing delay and microbial load of broiler neck skin samples.

    Science.gov (United States)

    Lucianez, A; Holmes, M A; Tucker, A W

    2010-01-01

    The measurable microbial load on poultry carcasses during processing is determined by a number of factors including farm or origin, processing hygiene, and external temperature. This study investigated associations between carcass microbial load and progressive delays to processing. A total of 30 carcasses were delayed immediately after defeathering and before evisceration in a commercial abattoir in groups of five, and were held at ambient temperature for 1, 2, 3, 4, 6, and 8 h. Delayed carcasses were reintroduced to the processing line, and quantitative assessment of total viable count, coliforms, Staphylococcus aureus, and Pseudomonas spp. was undertaken on neck skin flap samples collected after carcass chilling and then pooled for each group. Sampling was repeated on 5 separate days, and the data were combined. Significant increases in total viable count (P = 0.001) and coliforms (P = 0.004), but not for S. aureus or Pseudomonas loads, were observed across the 8-h period of delay. In line with previous studies, there was significant variation in microbiological data according to sampling day. In conclusion, there is a significant and measurable decline in microbiological status of uneviscerated but defeathered poultry carcasses after an 8-h delay, but the variability of sampling results, reflecting the wide range of factors that impact microbial load, means that it is not possible to determine maximum or minimum acceptable periods of processing delay based on this criterion alone.

  16. Microbial decontamination of polluted soil in a slurry process

    International Nuclear Information System (INIS)

    Geerdink, M.J.; Kleijntjens, R.H.; Loosdrecht, M.C.M. van; Luyben, K.C.A.M.

    1996-01-01

    Oil-contaminated soil (2.3--17 g/kg), even soil with high clay and silt content, was remediated microbiologically in a slurry reactor. The presence of soil, however, limits the degradation rate of oil. In contrast with results form experiments using oil dispersed in water, the relative composition of the oil components in a soil slurry after degradation was about the same as that of the original oil. Thus the composition of the degraded oil is the same as that of the original oil, which is indicative for a physical, rather than a (bio)chemical, limitation on the oil degradation rate. About 70% of the contaminant was readily available and was degraded in less than eight days. The dual injected turbulent suspension (DITS) reactor is able to combine remediation of part of the contaminated (polydisperse) soil with separation of the soil into a heavily and a lightly polluted fraction. In continuous operation, lowering the overall soil residence time from 200 to 100 h did not significantly increase the oil concentration in the effluent soil. Therefore a soil residence time of less than 100 h is feasible. With a residence time of 100 h, overall oil degradation rates at the steady state were more than 70 times faster than in a comparable land farm. After treatment in a DITS reactor, the remaining oil in the contaminated soil fraction is slowly released from the soil. From a batch experiment it was found that another 10 weeks were needed to reach the Dutch reference level of 50 mg/kg. This can be done in a process with a low energy input, such as a landfarm

  17. Microbial network of the carbonate precipitation process induced by microbial consortia and the potential application to crack healing in concrete.

    Science.gov (United States)

    Zhang, Jiaguang; Zhou, Aijuan; Liu, Yuanzhen; Zhao, Bowei; Luan, Yunbo; Wang, Sufang; Yue, Xiuping; Li, Zhu

    2017-11-06

    Current studies have employed various pure-cultures for improving concrete durability based on microbially induced carbonate precipitation (MICP). However, there have been very few reports concerned with microbial consortia, which could perform more complex tasks and be more robust in their resistance to environmental fluctuations. In this study, we constructed three microbial consortia that are capable of MICP under aerobic (AE), anaerobic (AN) and facultative anaerobic (FA) conditions. The results showed that AE consortia showed more positive effects on inorganic carbon conversion than AN and FA consortia. Pyrosequencing analysis showed that clear distinctions appeared in the community structure between different microbial consortia systems. Further investigation on microbial community networks revealed that the species in the three microbial consortia built thorough energetic and metabolic interaction networks regarding MICP, nitrate-reduction, bacterial endospores and fermentation communities. Crack-healing experiments showed that the selected cracks of the three consortia-based concrete specimens were almost completely healed in 28 days, which was consistent with the studies using pure cultures. Although the economic advantage might not be clear yet, this study highlights the potential implementation of microbial consortia on crack healing in concrete.

  18. Bacteria and archaea communities in full-scale thermophilic and mesophilic anaerobic digesters treating food wastewater: Key process parameters and microbial indicators of process instability.

    Science.gov (United States)

    Lee, Joonyeob; Shin, Seung Gu; Han, Gyuseong; Koo, Taewoan; Hwang, Seokhwan

    2017-12-01

    In this study, four different mesophilic and thermophilic full-scale anaerobic digesters treating food wastewater (FWW) were monitored for 1-2years in order to investigate: 1) microbial communities underpinning anaerobic digestion of FWW, 2) significant factors shaping microbial community structures, and 3) potential microbial indicators of process instability. Twenty-seven bacterial genera were identified as abundant bacteria underpinning the anaerobic digestion of FWW. Methanosaeta harundinacea, M. concilii, Methanoculleus bourgensis, M. thermophilus, and Methanobacterium beijingense were revealed as dominant methanogens. Bacterial community structures were clearly differentiated by digesters; archaeal community structures of each digester were dominated by one or two methanogen species. Temperature, ammonia, propionate, Na + , and acetate in the digester were significant factors shaping microbial community structures. The total microbial populations, microbial diversity, and specific bacteria genera showed potential as indicators of process instability in the anaerobic digestion of FWW. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Novel developments in butanol fermentation: Microbial genetics to agricultural substrates, process technology, and downstream processing

    Science.gov (United States)

    Butanol is the major product of acetone-butanol-ethanol (ABE; ratio 3:6:1) fermentation. It can be produced from various carbohydrates such as glucose, corn, molasses, and whey permeate (a by-product of the dairy industry) using microbial strains such as Clostridium beijerinckii and/or C. acetobuty...

  20. Diets of differentially processed wheat alter ruminal fermentation parameters and microbial populations in beef cattle.

    Science.gov (United States)

    Jiang, S Z; Yang, Z B; Yang, W R; Li, Z; Zhang, C Y; Liu, X M; Wan, F C

    2015-11-01

    The influences of differently processed wheat products on rumen fermentation, microbial populations, and serum biochemistry profiles in beef cattle were studied. Four ruminally cannulated Limousin × Luxi beef cattle (400 ± 10 kg) were used in the experiment with a 4 × 4 Latin square design. The experimental diets contained (on a DM basis) 60% corn silage as a forage source and 40% concentrate with 4 differently processed wheat products (extruded, pulverized, crushed, and rolled wheat). Concentrations of ruminal NH-N and microbial protein (MCP) in cattle fed crushed and rolled wheat were greater ( Ruminal concentrations of total VFA and acetate and the ratio of acetate to propionate decreased ( 0.05). Our findings suggest that the method of wheat processing could have a significant effect on ruminal fermentation parameters and microbial populations in beef cattle and that crushed and rolled processing is better in terms of ruminal NH-N and MCP content, acetate-to-propionate ratio, and relative abundance of rumen microorganisms.

  1. The influence of processing on the microbial risk associated with Rooibos (Aspalathus linearis) tea.

    Science.gov (United States)

    Gouws, Pieter; Hartel, Toni; van Wyk, Rudean

    2014-12-01

    This review discusses the influence of processing on the microbial risk associated with Salmonella in Rooibos tea, the identification of Salmonella and preventative and control measures to control microbial contamination. Rooibos tea, like other plant products, naturally contains a high microbial load. Downstream processing steps of these products usually help in reducing any contaminants present. Due to the delicate flavour properties and nature of Rooibos, gentle processing techniques are necessary for the production of good quality tea. However, this has a major influence on the microbiological status of the product. The presence of Salmonella in Rooibos is poorly understood. The ubiquitous distribution of Salmonella in the natural environment and its prevalence in the global food chain, the physiological adaptability, virulence of the bacterial pathogen and its serious economic impact on the food industry, emphasises the need for continued awareness and stringent controls at all levels of food production. With the advances of technology and information at hand, the processing of Rooibos needs to be re-evaluated. Since the delicate nature of Rooibos prohibits the use of harsh methods to control Salmonella, alternative methods for the steam pasteurisation of Rooibos show great potential to control Salmonella in a fast, efficient and cost-effective manner. These alternative methods will significantly improve the microbiological quality of Rooibos and provide a product that is safe to consumers. © 2014 Society of Chemical Industry.

  2. Anaerobic digestion of slaughterhouse waste: main process limitations and microbial community interactions.

    Science.gov (United States)

    Palatsi, J; Viñas, M; Guivernau, M; Fernandez, B; Flotats, X

    2011-02-01

    Fresh pig/cattle slaughterhouse waste mixtures, with different lipid-protein ratios, were characterized and their anaerobic biodegradability assessed in batch tests. The resultant methane potentials were high (270-300 L(CH4) kg(-1)(COD)) making them interesting substrates for the anaerobic digestion process. However, when increasing substrate concentrations in consecutive batch tests, up to 15 g(COD) kg(-1), a clear inhibitory process was monitored. Despite the reported severe inhibition, related to lipid content, the system was able to recover activity and successfully degrade the substrate. Furthermore, 16SrRNA gene-based DGGE results showed an enrichment of specialized microbial populations, such as β-oxidizing/proteolitic bacteria (Syntrophomonas sp., Coprothermobacter sp. and Anaerobaculum sp.), and syntrophic methanogens (Methanosarcina sp.). Consequently, the lipid concentration of substrate and the structure of the microbial community are the main limiting factors for a successful anaerobic treatment of fresh slaughterhouse waste. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. Microbial phylogeny determines transcriptional response of resistome to dynamic composting processes

    OpenAIRE

    Wang, Cheng; Dong, Da; Strong, P. J.; Zhu, Weijing; Ma, Zhuang; Qin, Yong; Wu, Weixiang

    2017-01-01

    Background Animal manure is a reservoir of antibiotic resistance genes (ARGs) that pose a potential health risk globally, especially for resistance to the antibiotics commonly used in livestock production (such as tetracycline, sulfonamide, and fluoroquinolone). Currently, the effects of biological treatment (composting) on the transcriptional response of manure ARGs and their microbial hosts are not well characterized. Composting is a dynamic process that consists of four distinct phases tha...

  4. Feedstocks influence on the process parameters and the microbial community in anaerobic digestion

    OpenAIRE

    Ferguson, Robert Michael William

    2013-01-01

    To improve our understanding into the key parameters controlling and regulating the microbial groups involved in the anaerobic digestion (AD) process, particularly over multiple changes in operational conditions, triplicate lab-scale digesters fed with sewage sludge were exposed to single and multiple changes in organic loading rate (OLR) using either glycerol waste (a by-product of biodiesel manufacture), or Fats oils and greace (FOG waste) collected from a restaurant grease t...

  5. Microbial methane oxidation processes and technologies for mitigation of landfill gas emissions

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Kjeldsen, Peter; Bogner, J.E.

    2009-01-01

    Landfill gas containing methane is produced by anaerobic degradation of organic waste. Methane is a strong greenhouse gas and landfills are one of the major anthropogenic sources of atmospheric methane. Landfill methane may be oxidized by methanotrophic microorganisms in soils or waste materials...... to predict methane emissions from landfills. Additional research and technology development is needed before methane mitigation technologies utilizing microbial methane oxidation processes can become commercially viable and widely deployed....

  6. Side Effects of Nitrification Inhibitors on Non Target Microbial Processes in Soils

    OpenAIRE

    Johannes Carl Gottlieb Ottow; Gero Benckiser; Ferisman Tindaon

    2011-01-01

    Agricultural chemicals have been used extensively in modern agriculture and toxicological studies suggest a great potential for inducing undesirable effects on non target organisms. A model experiment was conducted in order to determine side effects of three nitrification inhibitors (NIs, 3,4dimethylpyrazolephosphate = DMPP, 4-Chlormethylpyrazole phosphate = ClMPP and dicyandiamide = DCD) on non target microbial processes in soils. Side effects and dose response curve of three NIs were quanti...

  7. Flow-through Column Experiments and Modeling of Microbially Mediated Cr(VI) Reduction at Hanford 100H

    Science.gov (United States)

    Yang, L.; Molins, S.; Beller, H. R.; Brodie, E. L.; Steefel, C.; Nico, P. S.; Han, R.

    2010-12-01

    Microbially mediated Cr(VI) reduction at the Hanford 100H area was investigated by flow-through column experiments. Three separate experiments were conducted to promote microbial activities associated with denitrification, iron and sulfate reduction, respectively. Replicate columns packed with natural sediments from the site under anaerobic environment were injected with 5mM Lactate as the electron donor and 5 μM Cr(VI) in all experiments. Sulfate and nitrate solutions were added to act as the main electron acceptors in the respective experiments, while iron columns relied on the indigenous sediment iron (and manganese) oxides as electron acceptors. Column effluent solutions were analyzed by IC and ICP-MS to monitor the microbial consumption/conversion of lactate and the associated Cr(VI) reduction. Biogeochemical reactive transport modeling was performed to gain further insights into the reaction mechanisms and Cr(VI) bioreduction rates. All experimental columns showed a reduction of the injected Cr(VI). Columns under denitrifying conditions showed the least Cr(VI) reduction at early stages (simulations indicated that biomass growth completely depleted influent ammonium, and called for an additional source of N to account for the measured reduction rates. Iron columns were the least active with undetectable consumption of the injected lactate, slowest cell growth, and the smallest change in Cr(VI) concentrations during the course of the experiment. In contrast, columns under sulfate-reducing/fermentative conditions exhibited the greatest Cr(VI) reduction capacity. Two sulfate columns evolved to complete lactate fermentation with acetate and propionate produced in the column effluent after 40 days of experiments. These fermenting columns showed a complete removal of injected Cr(VI), visible precipitation of sulfide minerals, and a significant increase in effluent Fe and Mn concentrations. Reactive transport simulations suggested that direct reduction of Cr(VI) by

  8. Nutrient Enrichment Mediates the Relationships of Soil Microbial Respiration with Climatic Factors in an Alpine Meadow

    Directory of Open Access Journals (Sweden)

    Ning Zong

    2015-01-01

    Full Text Available Quantifying the effects of nutrient additions on soil microbial respiration (Rm and its contribution to soil respiration (Rs are of great importance for accurate assessment ecosystem carbon (C flux. Nitrogen (N addition either alone (coded as LN and HN or in combination with phosphorus (P (coded as LN + P and HN + P were manipulated in a semiarid alpine meadow on the Tibetan Plateau since 2008. Either LN or HN did not affect Rm, while LN + P enhanced Rm during peak growing periods, but HN + P did not affect Rm. Nutrient addition also significantly affected Rm/Rs, and the correlations of Rm/Rs with climatic factors varied with years. Soil water content (Sw was the main factor controlling the variations of Rm/Rs. During the years with large rainfall variations, Rm/Rs was negatively correlated with Sw, while, in years with even rainfall, Rm/Rs was positively correlated with Sw. Meanwhile, in N + P treatments the controlling effects of climatic factors on Rm/Rs were more significant than those in CK. Our results indicate that the sensitivity of soil microbes to climatic factors is regulated by nutrient enrichment. The divergent effects of Sw on Rm/Rs suggest that precipitation distribution patterns are key factors controlling soil microbial activities and ecosystem C fluxes in semiarid alpine meadow ecosystems.

  9. Spectral induced polarization and electrodic potential monitoring of microbially mediated iron sulfide transformations

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Susan; Personna, Y.R.; Ntarlagiannis, D.; Slater, L.; Yee, N.; O' Brien, M.; Hubbard, S.

    2008-02-15

    Stimulated sulfate-reduction is a bioremediation technique utilized for the sequestration of heavy metals in the subsurface.We performed laboratory column experiments to investigate the geoelectrical response of iron sulfide transformations by Desulfo vibriovulgaris. Two geoelectrical methods, (1) spectral induced polarization (SIP), and (2) electrodic potential measurements, were investigated. Aqueous geochemistry (sulfate, lactate, sulfide, and acetate), observations of precipitates (identified from electron microscopy as iron sulfide), and electrodic potentials on bisulfide ion (HS) sensitive silver-silver chloride (Ag-AgCl) electrodes (630 mV) were diagnostic of induced transitions between an aerobic iron sulfide forming conditions and aerobic conditions promoting iron sulfide dissolution. The SIP data showed 10m rad anomalies during iron sulfide mineralization accompanying microbial activity under an anaerobic transition. These anomalies disappeared during iron sulfide dissolution under the subsequent aerobic transition. SIP model parameters based on a Cole-Cole relaxation model of the polarization at the mineral-fluid interface were converted to (1) estimated biomineral surface area to pore volume (Sp), and (2) an equivalent polarizable sphere diameter (d) controlling the relaxation time. The temporal variation in these model parameters is consistent with filling and emptying of pores by iron sulfide biofilms, as the system transitions between anaerobic (pore filling) and aerobic (pore emptying) conditions. The results suggest that combined SIP and electrodic potential measurements might be used to monitor spatiotemporal variability in microbial iron sulfide transformations in the field.

  10. Prebiotics Mediate Microbial Interactions in a Consortium of the Infant Gut Microbiome.

    Science.gov (United States)

    Medina, Daniel A; Pinto, Francisco; Ovalle, Aline; Thomson, Pamela; Garrido, Daniel

    2017-10-04

    Composition of the gut microbiome is influenced by diet. Milk or formula oligosaccharides act as prebiotics, bioactives that promote the growth of beneficial gut microbes. The influence of prebiotics on microbial interactions is not well understood. Here we investigated the transformation of prebiotics by a consortium of four representative species of the infant gut microbiome, and how their interactions changed with dietary substrates. First, we optimized a culture medium resembling certain infant gut parameters. A consortium containing Bifidobacterium longum subsp. infantis , Bacteroides vulgatus , Escherichia coli and Lactobacillus acidophilus was grown on fructooligosaccharides (FOS) or 2'-fucosyllactose (2FL) in mono- or co-culture. While Bi. infantis and Ba. vulgatus dominated growth on 2FL, their combined growth was reduced. Besides, interaction coefficients indicated strong competition, especially on FOS. While FOS was rapidly consumed by the consortium, B. infantis was the only microbe displaying significant consumption of 2FL. Acid production by the consortium resembled the metabolism of microorganisms dominating growth in each substrate. Finally, the consortium was tested in a bioreactor, observing similar predominance but more pronounced acid production and substrate consumption. This study indicates that the chemical nature of prebiotics modulate microbial interactions in a consortium of infant gut species.

  11. Prebiotics Mediate Microbial Interactions in a Consortium of the Infant Gut Microbiome

    Directory of Open Access Journals (Sweden)

    Daniel A. Medina

    2017-10-01

    Full Text Available Composition of the gut microbiome is influenced by diet. Milk or formula oligosaccharides act as prebiotics, bioactives that promote the growth of beneficial gut microbes. The influence of prebiotics on microbial interactions is not well understood. Here we investigated the transformation of prebiotics by a consortium of four representative species of the infant gut microbiome, and how their interactions changed with dietary substrates. First, we optimized a culture medium resembling certain infant gut parameters. A consortium containing Bifidobacterium longum subsp. infantis, Bacteroides vulgatus, Escherichia coli and Lactobacillus acidophilus was grown on fructooligosaccharides (FOS or 2′-fucosyllactose (2FL in mono- or co-culture. While Bi. infantis and Ba. vulgatus dominated growth on 2FL, their combined growth was reduced. Besides, interaction coefficients indicated strong competition, especially on FOS. While FOS was rapidly consumed by the consortium, B. infantis was the only microbe displaying significant consumption of 2FL. Acid production by the consortium resembled the metabolism of microorganisms dominating growth in each substrate. Finally, the consortium was tested in a bioreactor, observing similar predominance but more pronounced acid production and substrate consumption. This study indicates that the chemical nature of prebiotics modulate microbial interactions in a consortium of infant gut species.

  12. Interactions in the Geo-Biosphere: Processes of Carbonate Precipitation in Microbial Mats

    Science.gov (United States)

    Dupraz, C.; Visscher, P. T.

    2009-12-01

    Microbial communities are situated at the interface between the biosphere, the lithosphere and the hydrosphere. These microbes are key players in the global carbon cycle, where they influence the balance between the organic and inorganic carbon reservoirs. Microbial populations can be organized in microbial mats, which can be defined as organosedimentary biofilms that are dominated by cyanobacteria, and exhibit tight coupling of element cycles. Complex interactions between mat microbes and their surrounding environment can result in the precipitation of carbonate minerals. This process refers as ‘organomineralization sensu lato' (Dupraz et al. in press), which differs from ‘biomineralization’ (e.g., in shells and bones) by lacking genetic control on the mineral product. Organomineralization can be: (1) active, when microbial metabolic reactions are responsible for the precipitation (“biologically-induced” mineralization) or (2) passive, when mineralization within a microbial organic matrix is environmentally driven (e.g., through degassing or desiccation) (“biologically-influenced” mineralization). Studying microbe-mineral interactions is essential to many emerging fields of the biogeoscience, such as the study of life in extreme environments (e.g, deep biosphere), the origin of life, the search for traces of extraterrestrial life or the seek of new carbon sink. This research approach combines sedimentology, biogeochemistry and microbiology. Two tightly coupled components that control carbonate organomineralization s.l.: (1) the alkalinity engine and (2) the extracellular organic matter (EOM), which is ultimately the location of mineral nucleation. Carbonate alkalinity can be altered both by microbial metabolism and environmental factors. In microbial mats, the net accumulation of carbonate minerals often reflect the balance between metabolic activities that consume/produce CO2 and/or organic acids. For example, photosynthesis and sulfate reduction

  13. Sourdough microbial community dynamics: An analysis during French organic bread-making processes.

    Science.gov (United States)

    Lhomme, Emilie; Urien, Charlotte; Legrand, Judith; Dousset, Xavier; Onno, Bernard; Sicard, Delphine

    2016-02-01

    Natural sourdoughs are commonly used in bread-making processes, especially for organic bread. Despite its role in bread flavor and dough rise, the stability of the sourdough microbial community during and between bread-making processes is debated. We investigated the dynamics of lactic acid bacteria (LAB) and yeast communities in traditional organic sourdoughs of five French bakeries during the bread-making process and several months apart using classical and molecular microbiology techniques. Sourdoughs were sampled at four steps of the bread-making process with repetition. The analysis of microbial density over 68 sourdough/dough samples revealed that both LAB and yeast counts changed along the bread-making process and between bread-making runs. The species composition was less variable. A total of six LAB and nine yeast species was identified from 520 and 1675 isolates, respectively. The dominant LAB species was Lactobacillus sanfranciscensis, found for all bakeries and each bread-making run. The dominant yeast species changed only once between bread-making processes but differed between bakeries. They mostly belonged to the Kazachstania clade. Overall, this study highlights the change of population density within the bread-making process and between bread-making runs and the relative stability of the sourdough species community during bread-making process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Microbial processes need to be addressed in a competent safety case

    International Nuclear Information System (INIS)

    Pedersen, Karsten; Hallbeck, Lotta

    2014-01-01

    Biological life processes should be separated from chemical inorganic processes. This is because most life processes are running along biochemical process pathways that are very different from those of inorganic chemical processes. Many chemical processes are restricted by various reaction barriers, e.g. the reduction process of sulphate to sulphide. They are, therefore, very slow or not possible at all under conditions typical for repositories for interim storage and long-term storage of radioactive wastes. Biological processes, consequently, include many reactions that do not occur in sterile, lifeless chemical systems. This is because life has the ability to over-run activation energy barriers and other energetic circumstances that block spontaneous chemical reactions. Life is possible from -20 deg. C up to around 113 deg. C, where all life processes stop. Life is also possible within a large pH range, from pH 1 up to at least pH 12.5. Finally, many processes overlap biology and chemistry such as sulphide and ferrous iron oxidation, which occur both as chemical and biological processes. Life processes in radioactive waste interim and long-term repositories will almost exclusively be under the control of micro-organisms. Microbial processes comprise red-ox reactions with decomposition and the production of organic molecules with different electron donors, energy sources and electron acceptors. Organic carbon in wastes, buffer materials and reduced inorganic molecules such as H2 from anaerobic corrosion processes and methane from geological sources are possible electron donors and energy sources for microbial processes. During the microbial oxidation of these energy sources, micro-organisms preferentially reduce electron acceptors in a particular order. First O 2 , and thereafter nitrate, manganese(IV), ferric iron, sulphate, sulphur and carbon dioxide are reduced. Simultaneously, fermentative processes lower pH and supply the metabolising micro-organisms with

  15. Understanding aquatic microbial processes using EEM's and in-situ fluorescence sensors

    Science.gov (United States)

    Fox, Bethany; Attridge, John; Rushworth, Cathy; Cox, Tim; Anesio, Alexandre; Reynolds, Darren

    2015-04-01

    The diverse origin of dissolved organic matter (DOM) in aquatic systems is well documented within the literature. Previous literature indicates that coloured dissolved organic matter (CDOM) is, in part, transformed by aquatic microbial processes, and that dissolved organic material derived from a microbial origin exhibits tryptophan-like fluorescence. However, this phenomenon is not fully understood and very little data is available within the current literature. The overall aim of our work is to reveal the microbial-CDOM interactions that give rise to the observed tryptophan-like fluorescence. The work reported here investigates the microbial processes that occur within freshwater aquatic samples, as defined by the biochemical oxygen demand (BOD) test, as a function of the T1 peak (λex/em 280/330-370 nm). A series of standard water samples were prepared using glucose, glutamic acid, BOD dilution water and a bacterial seed (Cole-Parmer BOD microbe capsules). Samples were spiked with CDOM (derived from an environmental water body) and subjected to time resolved BOD analysis and as excitation-emission fluorescence spectroscopy. All EEM spectral data was interrogated using parallel factor analysis (PARAFAC) in an attempt to determine the presence and dominance (relative intensities) of the CDOM-related and T1-related fluorophores within the samples. In-situ fluorescence sensors (Chelsea Technologies Group Ltd.) were also used to monitor the T1 fluorescence peak (UviLux Tryptophan) and the CDOM fluorescence peak (UviLux CDOM) during experiments. Tryptophan-like fluorescence was observed (albeit transient) in both spiked and un-spiked standard water samples. By furthering our understanding of aquatic organic matter fluorescence, its origin, transformation, fate and interaction with aquatic microbiological processes, we aim to inform the design of a new generation in-situ fluorescence sensor for the monitoring of aquatic ecosystem health.

  16. Functional Enzyme-Based Approach for Linking Microbial Community Functions with Biogeochemical Process Kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Li, Minjing [School; Qian, Wei-jun [Pacific Northwest National Laboratory, Richland, Washington 99354, United States; Gao, Yuqian [Pacific Northwest National Laboratory, Richland, Washington 99354, United States; Shi, Liang [School; Liu, Chongxuan [Pacific Northwest National Laboratory, Richland, Washington 99354, United States; School

    2017-09-28

    The kinetics of biogeochemical processes in natural and engineered environmental systems are typically described using Monod-type or modified Monod-type models. These models rely on biomass as surrogates for functional enzymes in microbial community that catalyze biogeochemical reactions. A major challenge to apply such models is the difficulty to quantitatively measure functional biomass for constraining and validating the models. On the other hand, omics-based approaches have been increasingly used to characterize microbial community structure, functions, and metabolites. Here we proposed an enzyme-based model that can incorporate omics-data to link microbial community functions with biogeochemical process kinetics. The model treats enzymes as time-variable catalysts for biogeochemical reactions and applies biogeochemical reaction network to incorporate intermediate metabolites. The sequences of genes and proteins from metagenomes, as well as those from the UniProt database, were used for targeted enzyme quantification and to provide insights into the dynamic linkage among functional genes, enzymes, and metabolites that are necessary to be incorporated in the model. The application of the model was demonstrated using denitrification as an example by comparing model-simulated with measured functional enzymes, genes, denitrification substrates and intermediates

  17. Effects of microbial processes on gas generation under expected WIPP repository conditions: Annual report through 1992

    International Nuclear Information System (INIS)

    Francis, A.J.; Gillow, J.B.

    1993-09-01

    Microbial processes involved in gas generation from degradation of the organic constituents of transuranic waste under conditions expected at the Waste Isolation Pilot Plant (WIPP) repository are being investigated at Brookhaven National Laboratory. These laboratory studies are part of the Sandia National Laboratories -- WIPP Gas Generation Program. Gas generation due to microbial degradation of representative cellulosic waste was investigated in short-term ( 6 months) experiments by incubating representative paper (filter paper, paper towels, and tissue) in WIPP brine under initially aerobic (air) and anaerobic (nitrogen) conditions. Samples from the WIPP surficial environment and underground workings harbor gas-producing halophilic microorganisms, the activities of which were studied in short-term experiments. The microorganisms metabolized a variety of organic compounds including cellulose under aerobic, anaerobic, and denitrifying conditions. In long-term experiments, the effects of added nutrients (trace amounts of ammonium nitrate, phosphate, and yeast extract), no nutrients, and nutrients plus excess nitrate on gas production from cellulose degradation

  18. Good Manufacturing Practices and Microbial Contamination Sources in Orange Fleshed Sweet Potato Puree Processing Plant in Kenya

    Directory of Open Access Journals (Sweden)

    Derick Nyabera Malavi

    2018-01-01

    Full Text Available Limited information exists on the status of hygiene and probable sources of microbial contamination in Orange Fleshed Sweet Potato (OFSP puree processing. The current study is aimed at determining the level of compliance to Good Manufacturing Practices (GMPs, hygiene, and microbial quality in OFSP puree processing plant in Kenya. Intensive observation and interviews using a structured GMPs checklist, environmental sampling, and microbial analysis by standard microbiological methods were used in data collection. The results indicated low level of compliance to GMPs with an overall compliance score of 58%. Microbial counts on food equipment surfaces, installations, and personnel hands and in packaged OFSP puree were above the recommended microbial safety and quality legal limits. Steaming significantly (P<0.05 reduced microbial load in OFSP cooked roots but the counts significantly (P<0.05 increased in the puree due to postprocessing contamination. Total counts, yeasts and molds, Enterobacteriaceae, total coliforms, and E. coli and S. aureus counts in OFSP puree were 8.0, 4.0, 6.6, 5.8, 4.8, and 5.9 log10 cfu/g, respectively. In conclusion, equipment surfaces, personnel hands, and processing water were major sources of contamination in OFSP puree processing and handling. Plant hygiene inspection, environmental monitoring, and food safety trainings are recommended to improve hygiene, microbial quality, and safety of OFSP puree.

  19. Profiling of dynamic changes in the microbial community during the soy sauce fermentation process.

    Science.gov (United States)

    Wei, Quanzeng; Wang, Hongbin; Chen, Zhixin; Lv, Zhijia; Xie, Yufeng; Lu, Fuping

    2013-10-01

    Soy sauce is a traditional condiment manufactured by natural inoculation and mixed culture fermentation. As is well known, it is the microbial community that plays an important role in the formation of its flavors. However, to date, its dynamic changes during the long period of fermentation process are still unclear, intensively constraining the improvement and control of the soy sauce quality. In this work, we revealed the dynamic changes of the microbial community by combining a cultured dependent method and a cultured independent method of polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis. Results indicated that the two methods verified and complemented each other in profiling microbial community, and that significant dynamics of the microbial community existed during the fermentation process, especially the strong inhibition of the growth of most of the microbes when entering into the mash stage from the koji stage. In the analysis of bacterial community, Staphylococcus and Bacillus were found to be the dominant bacteria and detected in the whole fermentation process. Kurthia and Klebsiella began to appear in the koji stage and then fade away in the early stage of the mash fermentation. In the analysis of fungal community, Aspergillus sojae and Zygosaccharomyces rouxii were found to be the dominant fungi in the koji and mash fermentation, respectively. It was clearly shown that when A. sojae decreased and disappeared in the middle stage of the mash fermentation, Z. rouxii appeared and increased at the meantime. Aspergillus parasiticus, Trichosporon ovoides and Trichosporon asahii also appeared in the koji and the early period of the mash fermentation and disappeared thereafter. Similar to Z. rouxii, Millerozyma farinosa and Peronospora farinosa were also found spontaneously which appeared in the mid-late period of the mash fermentation. The principal component analysis suggested that the microbial community underwent significant changes in

  20. The effect of salinity, redox mediators and temperature on anaerobic biodegradation of petroleum hydrocarbons in microbial fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Adelaja, Oluwaseun, E-mail: o.adelaja@my.westminster.ac.uk; Keshavarz, Tajalli, E-mail: t.keshavarz@westminster.ac.uk; Kyazze, Godfrey, E-mail: g.kyazze@westminster.ac.uk

    2015-02-11

    Highlights: • Effective degradation of petroleum hydrocarbon mixtures was achieved using MFC. • Adapted anaerobic microbial consortium was used as inoculum. • Bio-electricity generation was enhanced by 30-fold when riboflavin, was added. • Optimum MFC performance was obtained at mesophilic and moderately saline conditions. • Stable MFC performance was obtained during prolonged fed-batch MFC operation. - Abstract: Microbial fuel cells (MFCs) need to be robust if they are to be applied in the field for bioremediation. This study investigated the effect of temperature (20–50 °C), salinity (0.5–2.5% (w/v) as sodium chloride), the use of redox mediators (riboflavin and anthraquinone-2-sulphonate, AQS) and prolonged fed-batch operation (60 days) on biodegradation of a petroleum hydrocarbon mix (i.e. phenanthrene and benzene) in MFCs. The performance criteria were degradation efficiency, % COD removal and electrochemical performance. Good electrochemical and degradation performance were maintained up to a salinity of 1.5% (w/v) but deteriorated by 35-fold and 4-fold respectively as salinity was raised to 2.5%w/v. Degradation rates and maximum power density were both improved by approximately 2-fold at 40 °C compared to MFC performance at 30 °C but decreased sharply by 4-fold when operating temperature was raised to 50 °C. The optimum reactor performance obtained at 40 °C was 1.15 mW/m{sup 2} maximum power density, 89.1% COD removal and a degradation efficiency of 97.10%; at moderately saline (1% w/v) conditions the maximum power density was 1.06 mW/m{sup 2}, 79.1% COD removal and 91.6% degradation efficiency. This work suggests the possible application of MFC technology in the effective treatment of petroleum hydrocarbons contaminated site and refinery effluents.

  1. The effect of salinity, redox mediators and temperature on anaerobic biodegradation of petroleum hydrocarbons in microbial fuel cells

    International Nuclear Information System (INIS)

    Adelaja, Oluwaseun; Keshavarz, Tajalli; Kyazze, Godfrey

    2015-01-01

    Highlights: • Effective degradation of petroleum hydrocarbon mixtures was achieved using MFC. • Adapted anaerobic microbial consortium was used as inoculum. • Bio-electricity generation was enhanced by 30-fold when riboflavin, was added. • Optimum MFC performance was obtained at mesophilic and moderately saline conditions. • Stable MFC performance was obtained during prolonged fed-batch MFC operation. - Abstract: Microbial fuel cells (MFCs) need to be robust if they are to be applied in the field for bioremediation. This study investigated the effect of temperature (20–50 °C), salinity (0.5–2.5% (w/v) as sodium chloride), the use of redox mediators (riboflavin and anthraquinone-2-sulphonate, AQS) and prolonged fed-batch operation (60 days) on biodegradation of a petroleum hydrocarbon mix (i.e. phenanthrene and benzene) in MFCs. The performance criteria were degradation efficiency, % COD removal and electrochemical performance. Good electrochemical and degradation performance were maintained up to a salinity of 1.5% (w/v) but deteriorated by 35-fold and 4-fold respectively as salinity was raised to 2.5%w/v. Degradation rates and maximum power density were both improved by approximately 2-fold at 40 °C compared to MFC performance at 30 °C but decreased sharply by 4-fold when operating temperature was raised to 50 °C. The optimum reactor performance obtained at 40 °C was 1.15 mW/m 2 maximum power density, 89.1% COD removal and a degradation efficiency of 97.10%; at moderately saline (1% w/v) conditions the maximum power density was 1.06 mW/m 2 , 79.1% COD removal and 91.6% degradation efficiency. This work suggests the possible application of MFC technology in the effective treatment of petroleum hydrocarbons contaminated site and refinery effluents

  2. Relationship of microbial processes to the fate and behavior of transuranic elements in soils, plants, and animals

    International Nuclear Information System (INIS)

    Wildung, R.E.; Garland, T.R.

    1977-10-01

    This review considers the influence of soil physicochemical and microbial processes on the long-term solubility, form, and bioavailability of plutonium and other transuranic elements important in the nuclear fuel cycle. Emphasis is placed on delineation of the relationships between soil chemical and microbial processes and the role of soil microorganisms in effecting solubilization, transformation and plant/animal uptake of elements considered largely insoluble in soils strictly on the basis of their inorganic chemical characteristics

  3. Microbial processes relevant for the long-term performance of radioactive waste repositories in clays

    International Nuclear Information System (INIS)

    Meleshyn, Artur

    2012-01-01

    Document available in extended abstract form only. A number of investigations on occurrence and viability of microbes in compacted clays have been aimed at studying possible microbial effects on long-term performance of a deep geological repository (DGR) for high-level radioactive waste (HLW) and spent nuclear fuel (SF). Compacted clays are considered in current DGR designs either as a buffer material or as a host rock. The primary purpose of the present work was to qualitatively evaluate the relevance of microbial activity for the long-term performance of a DGR and to identify which safety-relevant processes and properties can be potentially influenced by this activity. The present analysis identified eight clay properties essential for maintaining safety functions of containment and retardation of the disposal system - swelling pressure, specific surface area, cation exchange capacity, anion sorption capacity, porosity, permeability, fluid pressure, plasticity - which can potentially be influenced by microbial processes in clay buffer and Clay-stone within a DGR for HLW/SF. Iron(III)- and sulphate-reducing, fermentative, methane-producing and oxidizing microbes can be considered to be present in any clay formation. Each habitat includes a massive number of microbial niches with perhaps only a small proportion of the species being metabolically active at the habitat's conditions, the remainder becoming not extinct. Moreover, clays contain electron donors and electron acceptors in amounts sufficient for these microbes to remain active during very long periods of time. Additional sources of electron donors or electron acceptors will inevitably be added to the repository system as a result of DGR excavation, placement of radioactive waste as well as backfilling and sealing of the DGR. In no case should the potential impact of microbes be underestimated based on a possible argument of comparably low biomass of the microbes in contact with metal surfaces or dissolved

  4. Microbial phylogeny determines transcriptional response of resistome to dynamic composting processes.

    Science.gov (United States)

    Wang, Cheng; Dong, Da; Strong, P J; Zhu, Weijing; Ma, Zhuang; Qin, Yong; Wu, Weixiang

    2017-08-16

    Animal manure is a reservoir of antibiotic resistance genes (ARGs) that pose a potential health risk globally, especially for resistance to the antibiotics commonly used in livestock production (such as tetracycline, sulfonamide, and fluoroquinolone). Currently, the effects of biological treatment (composting) on the transcriptional response of manure ARGs and their microbial hosts are not well characterized. Composting is a dynamic process that consists of four distinct phases that are distinguished by the temperature resulting from microbial activity, namely the mesophilic, thermophilic, cooling, and maturing phases. In this study, changes of resistome expression were determined and related to active microbiome profiles during the dynamic composting process. This was achieved by integrating metagenomic and time series metatranscriptomic data for the evolving microbial community during composting. Composting noticeably reduced the aggregated expression level of the manure resistome, which primarily consisted of genes encoding for tetracycline, vancomycin, fluoroquinolone, beta-lactam, and aminoglycoside resistance, as well as efflux pumps. Furthermore, a varied transcriptional response of resistome to composting at the ARG levels was highlighted. The expression of tetracycline resistance genes (tetM-tetW-tetO-tetS) decreased during composting, where distinctive shifts in the four phases of composting were related to variations in antibiotic concentration. Composting had no effect on the expression of sulfonamide and fluoroquinolone resistance genes, which increased slightly during the thermophilic phase and then decreased to initial levels. As indigenous populations switched greatly throughout the dynamic composting, the core resistome persisted and their reservoir hosts' composition was significantly correlated with dynamic active microbial phylogenetic structure. Hosts for sulfonamide and fuoroquinolone resistance genes changed notably in phylognetic structure

  5. Microbial ecology of Vietnamese Tra fish (Pangasius hypophthalmus) fillets during processing.

    Science.gov (United States)

    Tong Thi, Anh Ngoc; Noseda, Bert; Samapundo, Simbarashe; Nguyen, Binh Ly; Broekaert, Katrien; Rasschaert, Geertrui; Heyndrickx, Marc; Devlieghere, Frank

    2013-10-15

    There are numerous factors that can have an impact on the microbial ecology and quality of frozen Pangasius hypophthalmus fillets during processing in Vietnam. The presence of spoilage bacteria along the processing line can shorten the shelf-life of thawed frozen fish products. Therefore, the spoilage microbiota throughout the processing chain of two companies (BC: large scale factory, chlorine-based process, BW: large scale factory, water-based process and SC: small scale factory, chlorine-based process) was identified by culture-dependent techniques and 16S rRNA gene sequencing. The microbiological counts were observed to be insignificantly different (p>0.05) between BC and BW. Surprisingly, chlorine treated fillets from the SC line were revealed to have significantly higher microbial counts than potable water treated fillets at BW line. This was determined to be a result of temperature abuse during processing at SC, with temperatures even greater than 10 °C being recorded from skinning onwards. On the contrary, the microbiota related to spoilage for BC and BW lines was determined by 16S rRNA gene sequencing to be more diverse than that on the SC line. A total of 174 isolates, 20 genera and 38 species were identified along the processing chains. The genera Aeromonas, Acinetobacter, Lactococcus and Enterococcus were prevalent at various processing steps on all the processing lines evaluated. A diverse range of isolates belonging to the Enterobacteriaceae such as Providencia, Shigella, Klebsiella, Enterobacter and Wautersiella were isolated from fillets sampled on the SC line whereas Serratia was only observed on fillets sampled on the BC and BW lines. The results can be used to improve Good Manufacturing Practices for processed Pangasius fillets and to select effective measures to prolong the shelf-life of thawed Vietnamese Pangasius fillets products. © 2013.

  6. [Microbial Processes and Genesis of Methane Gas Jets in the Coastal Areas of the Crimea Peninsula].

    Science.gov (United States)

    Malakhova, T V; Kanapatskii, T A; Egorov, V N; Malakhova, L V; Artemov, Yu G; Evtushenko, D B; Gulin, S B; Pimenov, N V

    2015-01-01

    Hydroasoustic techniques were used for detection and mapping of gas jet areas in the coastal regions of the Crimean peninsula. Gas seep areas in the bays Laspi, Khersones, and Kazach'ya were chosen for detailed microbiological investigation. The first type of gas jets, observed in the Laspi Bay, was probably associated with discarge of deep thermogenic methane along the faults. Methane isotopic composition was char- acterized by Δ13C of -35.3 degrees. While elevated rates of aerobic methane oxidation were revealed in the sandy sediments adjacent to the methane release site, no evidence of bacterial mats was found. The second type of gas emission, observed in the Khersones Bay, was accompanied by formation of bacterial biofilms of the "Thiodendron" microbial community type, predominated by filamentous, spirochete-like organisms, in the areas of gas seepage. The isotopic composition of methane was there considerably lower (-60.4 degrees), indicating a considerable contribution of modern microbial methane to the gas bubbles discharged in this bay. Activity of the third type of gas emission, the seeps of the Kazach'ya Bay, probably depended directly on modern microbial processes of organic matter degradation in the upper sediment layers. The rates of sulfate reduction and methanogenesis were 260 and 34 μmol dm(-3) day(-1), respectively. Our results indicate different mechanisms responsible for formation of methane jets in the Laspi Bay and in the coastal areas of the Heracles Peninsula, where the bays Kazach'ya and Khersones are located.

  7. Bioprocessing of coal - 10 - an application of microbial flotation to mineral processing

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, T. [and others] [CRIEPI, Abiko-shi (Japan). Abiko Research Lab.

    1996-09-01

    Microbial flotation for coal desulfurization is being developed. Pyrite in coal is removed by bacterial adhesion by changing the surface property of pyrite. The bacterial adhesion of Thiobacillus ferrooxidans to sulfide minerals (pyrite, galena, molybdenite, chalcocite and millerite), and pyrite removal from the mixture of these sulfide minerals by microbial flotation was investigated. To compare the adhesion of T. ferrooxidans to pyrite with that to the other four minerals mentioned, the surface areas of the minerals, where the bacterium could adhere, was measured. It was observed that the roughness on the mineral surfaces was much smaller than the size of the bacterial cells. Hence, it was suggested that the roughness did not affect the bacterial adhesion to mineral surfaces. Bacterial adhesion to pyrite was compared with that to the other minerals. The amount of adhering bacterium was estimated on the basis of the adherable surface area measured with microscopic method. The amount of adhering cells to pyrite was 421.6 x 10{sup 8} cells/cm{sup 2}. On the other hand, the amounts of adhering cells to the minerals, except for pyrite were in a range of 77.1 to 160.8 x 10{sup 8} cells/cm{sup 2}. The bacterium adheres more to pyrite than to the other minerals, and only adheres to pyrite even if the pyrite is mixed with other minerals. Hence, T. ferrooxidans could adhere selectively to pyrite. Pyrite removal from the mineral mixtures was investigated with microbial flotation. Pyrite removal was in a range of 83.7% to 95.1% and mineral recovery was 72.9% to 100%. The grade of recovered minerals was in a range of 79.2 to 86.0% and that of rejected pyrite was in a range of 78.7 to 90.0%. These results suggest that microbial flotation can be a novel technology for mineral processing.

  8. Conservation and variability in the structure and function of the Cas5d endoribonuclease in the CRISPR-mediated microbial immune system.

    Science.gov (United States)

    Koo, Yoon; Ka, Donghyun; Kim, Eun-Jin; Suh, Nayoung; Bae, Euiyoung

    2013-10-23

    Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins form an RNA-mediated microbial immune system against invading foreign genetic elements. Cas5 proteins constitute one of the most prevalent Cas protein families in CRISPR-Cas systems and are predicted to have RNA recognition motif (RRM) domains. Cas5d is a subtype I-C-specific Cas5 protein that can be divided into two distinct subgroups, one of which has extra C-terminal residues while the other contains a longer insertion in the middle of its N-terminal RRM domain. Here, we report crystal structures of Cas5d from Streptococcus pyogenes and Xanthomonas oryzae, which respectively represent the two Cas5d subgroups. Despite a common domain architecture consisting of an N-terminal RRM domain and a C-terminal β-sheet domain, the structural differences between the two Cas5d proteins are highlighted by the presence of a unique extended helical region protruding from the N-terminal RRM domain of X. oryzae Cas5d. We also demonstrate that Cas5d proteins possess not only specific endoribonuclease activity for CRISPR RNAs but also nonspecific double-stranded DNA binding affinity. These findings suggest that Cas5d may play multiple roles in CRISPR-mediated immunity. Furthermore, the specific RNA processing was also observed between S. pyogenes Cas5d protein and X. oryzae CRISPR RNA and vice versa. This cross-species activity of Cas5d provides a special opportunity for elucidating conserved features of the CRISPR RNA processing event. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Spatial variation in microbial processes controlling carbon mineralization within soils and sediments

    Energy Technology Data Exchange (ETDEWEB)

    Fendorf, Scott [Stanford Univ., CA (United States); Kleber, Markus [Oregon State Univ., Corvallis, OR (United States); Nico, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-10-19

    Soils have a defining role in global carbon cycling, having one of the largest dynamic stocks of C on earth—3300 Pg of C are stored in soils, which is three-times the amount stored in the atmosphere and more than the terrestrial land plants. An important control on soil organic matter (SOM) quantities is the mineralization rate. It is well recognized that the rate and extent of SOM mineralization is affected by climatic factors and mineral-organic matter associations. What remained elusive is to what extent constraints on microbial metabolism induced by the respiratory pathway, and specifically the electron acceptor in respiration, control overall rates of carbon mineralization in soils. Therefore, physical factors limiting oxygen diffusion such as soil texture and aggregate size (soil structure) may therefore be central controls on C mineralization rates. The goal of our research was therefore to determine if variations in microbial metabolic rates induced by anaerobic microsites in soils are a major control on SOM mineralization rates and thus storage. We performed a combination of laboratory experiments and field investigations will be performed to fulfill our research objectives. We used laboratory studies to examine fundamental factors of respiratory constraints (i.e., electron acceptor) on organic matter mineralization rates. We ground our laboratory studies with both manipulation of field samples and in-field measurements. Selection of the field sites is guided by variation in soil texture and structure while having (other environmental/soil factors constant. Our laboratory studies defined redox gradients and variations in microbial metabolism operating at the aggregate-scale (cm-scale) within soils using a novel constructed diffusion reactor. We further examined micro-scale variation in terminal electron accepting processes and resulting C mineralization rates within re-packed soils. A major outcome of our research is the ability to quantitatively place

  10. Nitrate-Mediated Microbially Enhanced Oil Recovery (N-MEOR) from model upflow bioreactors.

    Science.gov (United States)

    Gassara, Fatma; Suri, Navreet; Voordouw, Gerrit

    2017-02-15

    Microbially Enhanced Oil Recovery (MEOR) can enhance oil production with less energy input and less costs than other technologies. The present study used different aqueous electron donors (acetate, glucose, molasses) and an aqueous electron acceptor (nitrate) to stimulate growth of heterotrophic nitrate reducing bacteria (hNRB) to improve production of oil. Initial flooding of columns containing heavy oil (viscosity of 3400cP at 20°C) with CSBK (Coleville synthetic brine medium) produced 0.5 pore volume (PV) of oil. Bioreactors were then inoculated with hNRB with 5.8g/L of molasses and 0, 10, 20, 40, 60 or 80mM nitrate, as well as with 17mM glucose or 57mM acetate and 80mM nitrate. During incubations no oil was produced in the bioreactors that received 5.8g/L of molasses and 0, 10, 20, 40 or 60mM nitrate. However, the bioreactors injected with 5.8g/L of molasses, 17mM glucose or 57mM acetate and 80mM nitrate produced 13.9, 11.3±3.1 and 17.8±6.6% of residual oil, respectively. The significant production of oil from these bioreactors may be caused by N 2 -CO 2 gas production. Following continued injection with CSBK without nitrate, subsequent elution of significant residual oil (5-30%) was observed. These results also indicate possible involvement of fermentation products (organic acids, alcohols) to enhance heavy oil recovery. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Chemi-microbial processing of waste tire rubber: A project overview

    International Nuclear Information System (INIS)

    Romine, R.A.; Snowden-Swan, L.

    1993-12-01

    PNL is developing a method to use thiophillic microorganisms to devulcanize (biodesulfurize) the surface of ground rubber particles, which will improve the bonding and adhesion of the ground tire rubber into the virgin tire rubber matrix. The Chemi-microbial processing approach, introduced in this paper, is targeted at alleviating the waste tire problem in an environmentally conscious manner; it may also be applied to improve asphaltic materials and rubber and polymeric wastes to facilite their recycling. This paper outlines the logic and technical methods that will be used

  12. Good Manufacturing Practices and Microbial Contamination Sources in Orange Fleshed Sweet Potato Puree Processing Plant in Kenya

    Science.gov (United States)

    Abong', George Ooko

    2018-01-01

    Limited information exists on the status of hygiene and probable sources of microbial contamination in Orange Fleshed Sweet Potato (OFSP) puree processing. The current study is aimed at determining the level of compliance to Good Manufacturing Practices (GMPs), hygiene, and microbial quality in OFSP puree processing plant in Kenya. Intensive observation and interviews using a structured GMPs checklist, environmental sampling, and microbial analysis by standard microbiological methods were used in data collection. The results indicated low level of compliance to GMPs with an overall compliance score of 58%. Microbial counts on food equipment surfaces, installations, and personnel hands and in packaged OFSP puree were above the recommended microbial safety and quality legal limits. Steaming significantly (P contamination. Total counts, yeasts and molds, Enterobacteriaceae, total coliforms, and E. coli and S. aureus counts in OFSP puree were 8.0, 4.0, 6.6, 5.8, 4.8, and 5.9 log10 cfu/g, respectively. In conclusion, equipment surfaces, personnel hands, and processing water were major sources of contamination in OFSP puree processing and handling. Plant hygiene inspection, environmental monitoring, and food safety trainings are recommended to improve hygiene, microbial quality, and safety of OFSP puree. PMID:29808161

  13. Good Manufacturing Practices and Microbial Contamination Sources in Orange Fleshed Sweet Potato Puree Processing Plant in Kenya.

    Science.gov (United States)

    Malavi, Derick Nyabera; Muzhingi, Tawanda; Abong', George Ooko

    2018-01-01

    Limited information exists on the status of hygiene and probable sources of microbial contamination in Orange Fleshed Sweet Potato (OFSP) puree processing. The current study is aimed at determining the level of compliance to Good Manufacturing Practices (GMPs), hygiene, and microbial quality in OFSP puree processing plant in Kenya. Intensive observation and interviews using a structured GMPs checklist, environmental sampling, and microbial analysis by standard microbiological methods were used in data collection. The results indicated low level of compliance to GMPs with an overall compliance score of 58%. Microbial counts on food equipment surfaces, installations, and personnel hands and in packaged OFSP puree were above the recommended microbial safety and quality legal limits. Steaming significantly ( P contamination. Total counts, yeasts and molds, Enterobacteriaceae, total coliforms, and E. coli and S. aureus counts in OFSP puree were 8.0, 4.0, 6.6, 5.8, 4.8, and 5.9 log 10 cfu/g, respectively. In conclusion, equipment surfaces, personnel hands, and processing water were major sources of contamination in OFSP puree processing and handling. Plant hygiene inspection, environmental monitoring, and food safety trainings are recommended to improve hygiene, microbial quality, and safety of OFSP puree.

  14. Microbial Characterization of Table Olives Processed According to Spanish and Natural Styles

    Directory of Open Access Journals (Sweden)

    Daniela Campaniello

    2005-01-01

    Full Text Available A study on the microflora of table olives »Bella di Cerignola«, produced according to Spanish style and natural processing, is presented. The samples (olives and brines were taken at different fermentation phases; olives, before treatments, were analyzed too. pH was monitored and microbial populations were assessed by standard plate count. Determination of the following microbial groups was carried out: mesophilic bacteria, lactic acid bacteria, Enterobacteriaceae, Pseudomonadaceae, staphylococci, Micrococcaceae and yeasts. In the second phase, the identification of mesophilic bacteria, lactic acid bacteria and yeasts was performed. The amount of lactic acid bacteria and yeasts increased during the storage in all the samples, but no significant differences were observed between the two styles. At the end of fermentation an increase of Pseudomonadaceae cell load was observed, which was absent in the first phase of fermentation. The samples analyzed were extremely unsteady, therefore the addition of starter lactic acid bacteria could standardize olive processing. Lactobacillus plantarum, Bacillus spp. (mainly B. subtilis and Candida spp. were the predominant species at the end of the processing.

  15. Anaerobic microbial redox processes in a landfill leachate contaminated aquifer (Grindsted, Denmark)

    Science.gov (United States)

    Ludvigsen, L.; Albrechtsen, H.-J.; Heron, G.; Bjerg, P. L.; Christensen, T. H.

    1998-10-01

    The distribution of anaerobic microbial redox processes was investigated along a 305 m long transect of a shallow landfill-leachate polluted aquifer. By unamended bioassays containing sediment and groundwater, 37 samples were investigated with respect to methane production, sulfate, iron, and manganese reduction, and denitrification. Methane production was restricted to the most reduced part of the plume with rates of 0.003-0.055 nmol CH 4/g dry weight/day. Sulfate reduction was observed at rates of maximum 1.8 nmol SO 42-/g dry weight/day along with methane production in the plume, but sulfate reduction was also observed further downgradient of the landfill. Iron reduction at rates of 5-19 nmol Fe(II)/g dry weight/day was observed in only a few samples, but this may be related to a high detection limit for the iron reducing bioassay. Manganese reduction at rates of maximum 2.4 nmol Mn(II)/g dry weight/day and denitrification at rates of 0.2-37 nmol N 2O-N/g dry weight/day were observed in the less reduced part of the plume. All the redox processes were microbial processes. In many cases, several redox processes took place simultaneously, but in all samples one process dominated accounting for more than 70% of the equivalent carbon conversion. The bioassays showed that the redox zones in the plume identified from the groundwater composition (e.g. as methanogenic and sulfate reducing) locally hosted also other redox processes (e.g. iron reduction). This may have implications for the potential of the redox zone to degrade trace amounts of organic chemicals and suggests that unamended bioassays may be an important supplement to other approaches in characterizing the redox processes in an anaerobic plume.

  16. Changes in the Microbial Composition of Microbrewed Beer during the Process in the Actual Manufacturing Line.

    Science.gov (United States)

    Kim, S A; Jeon, S H; Kim, N H; Kim, H W; Lee, N Y; Cho, T J; Jung, Y M; Lee, S H; Hwang, I G; Rhee, M S

    2015-12-01

    This study investigated changes in the microbial composition of microbrewed beer during the manufacturing processes and identified potential microbial hazards, effective critical quality control points, and potential contamination routes. Comprehensive quantitative (aerobic plate count, lactic acid bacteria, fungi, acetic acid bacteria, coliforms, and Bacillus cereus) and qualitative (Escherichia coli and eight foodborne pathogens) microbiological analyses were performed using samples of raw materials (malt and manufacturing water), semiprocessed products (saccharified wort, boiled wort, and samples taken during the fermentation and maturation process), and the final product obtained from three plants. The initial aerobic plate count and lactic acid bacteria counts in malt were 5.2 and 4.3 log CFU/g, respectively. These counts were reduced to undetectable levels by boiling but were present at 2.9 and 0.9 log CFU/ml in the final product. Fungi were initially present at 3.6 log CFU/g, although again, the microbes were eliminated by boiling; however, the level in the final product was 4.6 log CFU/ml. No E. coli or foodborne pathogens (except B. cereus) were detected. B. cereus was detected at all stages, although it was not present in the water or boiled wort (total detection rate ¼ 16.4%). Results suggest that boiling of the wort is an effective microbial control measure, but careful management of raw materials and implementation of effective control measures after boiling are needed to prevent contamination of the product after the boiling step. The results of this study may constitute useful and comprehensive information regarding the microbiological quality of microbrewed beer.

  17. Spies and Bloggers: New Synthetic Biology Tools to Understand Microbial Processes in Soils and Sediments

    Science.gov (United States)

    Masiello, C. A.; Silberg, J. J.; Cheng, H. Y.; Del Valle, I.; Fulk, E. M.; Gao, X.; Bennett, G. N.

    2017-12-01

    Microbes can be programmed through synthetic biology to report on their behavior, informing researchers when their environment has triggered changes in their gene expression (e.g. in response to shifts in O2 or H2O), or when they have participated in a specific step of an elemental cycle (e.g. denitrification). This use of synthetic biology has the potential to significantly improve our understanding of microbes' roles in elemental and water cycling, because it allows reporting on the environment from the perspective of a microbe, matching the measurement scale exactly to the scale that a microbe experiences. However, synthetic microbes have not yet seen wide use in soil and sediment laboratory experiments because synthetic organisms typically report by fluorescing, making their signals difficult to detect outside the petri dish. We are developing a new suite of microbial programs that report instead by releasing easily-detected gases, allowing the real-time, noninvasive monitoring of behaviors in sediments and soils. Microbial biosensors can, in theory, be programmed to detect dynamic processes that contribute to a wide range of geobiological processes, including C cycling (biofilm production, methanogenesis, and synthesis of extracellular enzymes that degrade organic matter), N cycling (expression of enzymes that underlie different steps of the N cycle) and potentially S cycling. We will provide an overview of the potential uses of gas-reporting biosensors in soil and sediment lab experiments, and will report the development of the systematics of these sensors. Successful development of gas biosensors for laboratory use will require addressing issues including: engineering the intensity and selectivity of microbial gas production to maximize the signal to noise ratio; normalizing the gas reporter signal to cell population size, managing gas diffusion effects on signal shape; and developing multiple gases that can be used in parallel.

  18. Succession of the functional microbial communities and the metabolic functions in maize straw composting process.

    Science.gov (United States)

    Wei, Huawei; Wang, Liuhong; Hassan, Muhammad; Xie, Bing

    2018-05-01

    Illumina MiSeq sequencing and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) were applied to study the dynamic changes and effects of microbial community structures as well as the metabolic function of bacterial community in maize straw composting process. Results showed that humic acid contents in loosely combined humus (HA1) and stably combined humus (HA2) increased after composting and Staphylococcus, Cellulosimicrobium and Ochrobactrum possibly participated in the transformation of the process. The bacterial communities differed in different stages of the composting. Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria were reported the dominant phyla throughout the process and the relative abundance of the dominant phyla varied significantly (p composting. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Microbial processes associated with roots of bulbous rush coated with iron plaques

    Energy Technology Data Exchange (ETDEWEB)

    Kusel, K.; Chabbi, A.; Trinkwalter, T. [University of Bayreuth, Bayreuth (Germany). BITOEK

    2003-11-01

    The objectives of this work were to enumerate the microbes involved in the turnover of iron and organic root exudates in the rhizoplane, to investigate the effect of oxygen and pH on the utilization of these exudates by the rhizobacteria, and to study the ability of the root-colonizing microbiota to reduce sulfate. Enumeration studies done at pH 3 demonstrated that 10{sup 6} Fe(III) reducers and 10{sup 7} Fe(II) oxidizers g (fresh wt root){sup -1} were associated with Juncus roots. When roots were incubated in goethite-containing medium without and with supplemental glucose, Fe(II) was formed at rates approximating 1.1 mmol g (fresh wt root) {sup -1} d{sup -1} and 3.6 mmol g (fresh wt root){sup -1} d{sup -1} under anoxic conditions, respectively. These results suggest that a rapid microbially mediated cycling of iron occurs in the rhizosphere of Juncus roots under changing redox conditions. Most-probable-number estimates of aerobes and anaerobes capable of consuming root exudates at pH 3 were similar in the rhizosphere sediment and in Juncus roots, but numbers of aerobes were significantly higher than those of anaerobes. At pH 3, supplemental organic exudates were primarily subject to aerobic oxidation to CO{sub 2} and not subject to fermentation. However, at pH 4.5, root exudates were also rapidly utilized under anoxic conditions. Root-associated sulfate reduction was not observed at pH 3 to 4.5 but was observed at pH 4.9. The pH increased during all root-incubation studies both under oxic and anoxic conditions. Thus, as result of the microbial turnover of organic root exudates, pH and CO{sub 2} levels might be elevated at the root surface and favor Juncus plants to colonize acidic habitats.

  20. A multitrophic model to quantify the effects of marine viruses on microbial food webs and ecosystem processes

    DEFF Research Database (Denmark)

    Weitz, Joshua S.; Stock, Charles A.; Wilhelm, Steven W.

    2015-01-01

    Viral lysis of microbial hosts releases organic matter that can then be assimilated by nontargeted microorganisms. Quantitative estimates of virus-mediated recycling of carbon in marine waters, first established in the late 1990s, were originally extrapolated from marine host and virus densities......, host carbon content and inferred viral lysis rates. Yet, these estimates did not explicitly incorporate the cascade of complex feedbacks associated with virus-mediated lysis. To evaluate the role of viruses in shaping community structure and ecosystem functioning, we extend dynamic multitrophic...

  1. TopBP1-mediated DNA processing during mitosis.

    Science.gov (United States)

    Gallina, Irene; Christiansen, Signe Korbo; Pedersen, Rune Troelsgaard; Lisby, Michael; Oestergaard, Vibe H

    2016-01-01

    Maintenance of genome integrity is crucial to avoid cancer and other genetic diseases. Thus faced with DNA damage, cells mount a DNA damage response to avoid genome instability. The DNA damage response is partially inhibited during mitosis presumably to avoid erroneous processing of the segregating chromosomes. Yet our recent study shows that TopBP1-mediated DNA processing during mitosis is highly important to reduce transmission of DNA damage to daughter cells. (1) Here we provide an overview of the DNA damage response and DNA repair during mitosis. One role of TopBP1 during mitosis is to stimulate unscheduled DNA synthesis at underreplicated regions. We speculated that such genomic regions are likely to hold stalled replication forks or post-replicative gaps, which become the substrate for DNA synthesis upon entry into mitosis. Thus, we addressed whether the translesion pathways for fork restart or post-replicative gap filling are required for unscheduled DNA synthesis in mitosis. Using genetics in the avian DT40 cell line, we provide evidence that unscheduled DNA synthesis in mitosis does not require the translesion synthesis scaffold factor Rev1 or PCNA ubiquitylation at K164, which serve to recruit translesion polymerases to stalled forks. In line with this finding, translesion polymerase η foci do not colocalize with TopBP1 or FANCD2 in mitosis. Taken together, we conclude that TopBP1 promotes unscheduled DNA synthesis in mitosis independently of the examined translesion polymerases.

  2. Impacts of shallow geothermal energy production on redox processes and microbial communities.

    Science.gov (United States)

    Bonte, Matthijs; Röling, Wilfred F M; Zaura, Egija; van der Wielen, Paul W J J; Stuyfzand, Pieter J; van Breukelen, Boris M

    2013-12-17

    Shallow geothermal systems are increasingly being used to store or harvest thermal energy for heating or cooling purposes. This technology causes temperature perturbations exceeding the natural variations in aquifers, which may impact groundwater quality. Here, we report the results of laboratory experiments on the effect of temperature variations (5-80 °C) on redox processes and associated microbial communities in anoxic unconsolidated subsurface sediments. Both hydrochemical and microbiological data showed that a temperature increase from 11 °C (in situ) to 25 °C caused a shift from iron-reducing to sulfate-reducing and methanogenic conditions. Bioenergetic calculations could explain this shift. A further temperature increase (>45 °C) resulted in the emergence of a thermophilic microbial community specialized in fermentation and sulfate reduction. Two distinct maxima in sulfate reduction rates, of similar orders of magnitude (5 × 10(-10) M s(-1)), were observed at 40 and 70 °C. Thermophilic sulfate reduction, however, had a higher activation energy (100-160 kJ mol(-1)) than mesophilic sulfate reduction (30-60 kJ mol(-1)), which might be due to a trade-off between enzyme stability and activity with thermostable enzymes being less efficient catalysts that require higher activation energies. These results reveal that while sulfate-reducing functionality can withstand a substantial temperature rise, other key biochemical processes appear more temperature sensitive.

  3. Mediating processes between stress and problematic marijuana use.

    Science.gov (United States)

    Ketcherside, Ariel; Filbey, Francesca M

    2015-06-01

    The literature widely reports that stress is associated with marijuana use, yet, to date, the path from stress to marijuana-related problems has not been tested. In this study, we evaluated whether negative affect mediates the relationship between stress and marijuana use. To that end, we tested models to determine mediators between problems with marijuana use (via Marijuana Problem Scale), stress (via Early Life Stress Questionnaire, Perceived Stress Scale), and negative affect (via Beck Depression Inventory; Beck Anxiety Inventory) in 157 current heavy marijuana users. Mediation tests and bootstrap confidence intervals were carried out via the "Mediation" package in R. Depression and anxiety scores both significantly mediated the relationship between perceived stress and problematic marijuana use. Only depression significantly mediated the relationship between early life stress and problematic marijuana use. Early life stress, perceived stress and problematic marijuana use were significant only as independent variables and dependent variables. These findings demonstrate that (1) depression mediated both early life stress and perceived stress, and problematic marijuana use, and, (2) anxiety mediated perceived stress and problematic marijuana use. This mediation analysis represents a strong first step toward understanding the relationship between these variables; however, longitudinal studies are needed to determine causality between these variables. To conclude, addressing concomitant depression and anxiety in those who report either perceived stress or early life stress is important for the prevention of cannabis use disorders. Copyright © 2015. Published by Elsevier Ltd.

  4. Batch-batch stable microbial community in the traditional fermentation process of huyumei broad bean pastes.

    Science.gov (United States)

    Zhu, Linjiang; Fan, Zihao; Kuai, Hui; Li, Qi

    2017-09-01

    During natural fermentation processes, a characteristic microbial community structure (MCS) is naturally formed, and it is interesting to know about its batch-batch stability. This issue was explored in a traditional semi-solid-state fermentation process of huyumei, a Chinese broad bean paste product. The results showed that this MCS mainly contained four aerobic Bacillus species (8 log CFU per g), including B. subtilis, B. amyloliquefaciens, B. methylotrophicus, and B. tequilensis, and the facultative anaerobe B. cereus with a low concentration (4 log CFU per g), besides a very small amount of the yeast Zygosaccharomyces rouxii (2 log CFU per g). The dynamic change of the MCS in the brine fermentation process showed that the abundance of dominant species varied within a small range, and in the beginning of process the growth of lactic acid bacteria was inhibited and Staphylococcus spp. lost its viability. Also, the MCS and its dynamic change were proved to be highly reproducible among seven batches of fermentation. Therefore, the MCS naturally and stably forms between different batches of the traditional semi-solid-state fermentation of huyumei. Revealing microbial community structure and its batch-batch stability is helpful for understanding the mechanisms of community formation and flavour production in a traditional fermentation. This issue in a traditional semi-solid-state fermentation of huyumei broad bean paste was firstly explored. This fermentation process was revealed to be dominated by a high concentration of four aerobic species of Bacillus, a low concentration of B. cereus and a small amount of Zygosaccharomyces rouxii. Lactic acid bacteria and Staphylococcus spp. lost its viability at the beginning of fermentation. Such the community structure was proved to be highly reproducible among seven batches. © 2017 The Society for Applied Microbiology.

  5. Modelling the transport and decay processes of microbial tracers in a macro-tidal estuary.

    Science.gov (United States)

    Abu-Bakar, Amyrhul; Ahmadian, Reza; Falconer, Roger A

    2017-10-15

    The Loughor Estuary is a macro-tidal coastal basin, located along the Bristol Channel, in the South West of the U.K. The maximum spring tidal range in the estuary is up to 7.5 m, near Burry Port Harbour. This estuarine region can experience severe coastal flooding during high spring tides, including extreme flooding of the intertidal saltmarshes at Llanrhidian, as well as the lower industrial and residential areas at Llanelli and Gowerton. The water quality of this estuarine basin needs to comply with the designated standards for safe recreational bathing and shellfish harvesting industries. The waterbody however, potentially receives overloading of bacterial inputs that enter the estuarine system from both point and diffuse sources. Therefore, a microbial tracer study was carried out to get a better understanding of the faecal bacteria sources and to enable a hydro-environmental model to be refined and calibrated for both advection and dispersion transport. A two-dimensional hydro-environmental model has been refined and extended to predict the highest water level covering the intertidal floodplains of the Loughor Estuary. The validated hydrodynamic model for both water levels and currents, was included with the injected mass of microbial tracer, i.e. MS2 coliphage from upstream of the estuary, and modelled as a non-conservative tracer over several tidal cycles through the system. The calibration and validation of the transport and decay of microbial tracer was undertaken, by comparing the model results and the measured data at two different sampling locations. The refined model developed as a part of this study, was used to acquire a better understanding of the water quality processes and the potential sources of bacterial pollution in the estuary. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. New steady-state microbial community compositions and process performances in biogas reactors induced by temperature disturbances

    DEFF Research Database (Denmark)

    Luo, Gang; De Francisci, Davide; Kougias, Panagiotis

    2015-01-01

    that stochastic factors had a minor role in shaping the profile of the microbial community composition and activity in biogas reactors. On the contrary, temperature disturbance was found to play an important role in the microbial community composition as well as process performance for biogas reactors. Although...... three different temperature disturbances were applied to each biogas reactor, the increased methane yields (around 10% higher) and decreased volatile fatty acids (VFAs) concentrations at steady state were found in all three reactors after the temperature disturbances. After the temperature disturbance...... in shaping the profile of the microbial community composition and activity in biogas reactors. New steady-state microbial community profiles and reactor performances were observed in all the biogas reactors after the temperature disturbance....

  7. SPECIAL ISSUES REGARDING THE MEDIATION PROCESS IN THE COMMERCIAL FIELD

    Directory of Open Access Journals (Sweden)

    SEPTIMIU STOICA

    2012-05-01

    Full Text Available The purpose of the research subject to this paper is to find proper solutions for the increase of the volume and efficiency in the field of commercial mediation. Starting from practical remarks, after an analysis of the substance, a new concept is suggested to be included and put into operation, namely the special commercial mediation, and a plead is made for its use in the current activity of alternative dispute resolution. The first major objective of this paper is to demonstrate once again the need and utility of mediation in the commercial field, insisting though on its remarkable specific nature. The second objective is, starting from the outlined differences between the commercial mediation and the classical mediation, to define and to conceptualize the special commercial mediation, as a separate branch of mediation. The third objective of this paper is to draw the regime of the newly defined category of commercial mediation from a regulatory point of view, of the implementation structure and techniques as foreseen.

  8. Impact of microbial activity on the radioactive waste disposal: long term prediction of biocorrosion processes.

    Science.gov (United States)

    Libert, Marie; Schütz, Marta Kerber; Esnault, Loïc; Féron, Damien; Bildstein, Olivier

    2014-06-01

    This study emphasizes different experimental approaches and provides perspectives to apprehend biocorrosion phenomena in the specific disposal environment by investigating microbial activity with regard to the modification of corrosion rate, which in turn can have an impact on the safety of radioactive waste geological disposal. It is found that iron-reducing bacteria are able to use corrosion products such as iron oxides and "dihydrogen" as new energy sources, especially in the disposal environment which contains low amounts of organic matter. Moreover, in the case of sulphate-reducing bacteria, the results show that mixed aerobic and anaerobic conditions are the most hazardous for stainless steel materials, a situation which is likely to occur in the early stage of a geological disposal. Finally, an integrated methodological approach is applied to validate the understanding of the complex processes and to design experiments aiming at the acquisition of kinetic data used in long term predictive modelling of biocorrosion processes. © 2013.

  9. Modeling Microbial Processes in EPIC to Estimate Greenhouse Gas Emissions from soils

    Science.gov (United States)

    Schwab, D. E.; Izaurralde, R. C.; McGill, W. B.; Williams, J. R.; Schmid, E.

    2009-12-01

    Emissions of trace gases (CO2, N2O and CH4) to the atmosphere from managed terrestrial ecosystems have been contributing significantly to the warming of Earth. Trace gas production is dominated by biospheric processes. An improved knowledge of the soil-plant-atmosphere interface is of key importance for understanding trace gas dynamics. In soils, microbial metabolism plays a key role in the release or uptake of trace gases. Here we present work on the biophysical and biogeochemical model EPIC (Environmental Policy/Integrated Climate) to extend its capabilities to simulate CO2 and N2O fluxes in managed and unmanaged ecosystems. Emphasis will be given to recently developed, microbially-based, denitrification and nitrification modules. The soil-atmosphere exchange of trace gases can be measured by using various equipments, but often these measurements exhibit extreme space-time variability. We use hourly time steps to account for the variability induced by small changes in environmental conditions. Soils are often studied as macroscopic systems, although their functions are predominantly controlled at a microscopic level; i.e. the level of the microorganisms. We include these processes to the extent that these are known and can be quantitatively described. We represent soil dynamics mathematically with routines for gas diffusion, Michael Menten processes, electron budgeting and other processes such as uptake and transformations. We hypothesize that maximization of energy capture form scarce substrates using energetic favorable reactions drives evolution and that competitive advantage can result by depriving a competitor from a substrate. This Microbe Model changes concepts of production of N-containing trace gases; it unifies understanding of N oxidation and reduction, predicts production and evolution of trace gases and is consistent with observations of anaerobic ammonium oxidation.

  10. Microbial Analysis of Australian Dry Lake Cores; Analogs For Biogeochemical Processes

    Science.gov (United States)

    Nguyen, A. V.; Baldridge, A. M.; Thomson, B. J.

    2014-12-01

    Lake Gilmore in Western Australia is an acidic ephemeral lake that is analogous to Martian geochemical processes represented by interbedded phyllosilicates and sulfates. These areas demonstrate remnants of a global-scale change on Mars during the late Noachian era from a neutral to alkaline pH to relatively lower pH in the Hesperian era that continues to persist today. The geochemistry of these areas could possibly be caused by small-scale changes such as microbial metabolism. Two approaches were used to determine the presence of microbes in the Australian dry lake cores: DNA analysis and lipid analysis. Detecting DNA or lipids in the cores will provide evidence of living or deceased organisms since they provide distinct markers for life. Basic DNA analysis consists of extraction, amplification through PCR, plasmid cloning, and DNA sequencing. Once the sequence of unknown DNA is known, an online program, BLAST, will be used to identify the microbes for further analysis. The lipid analysis approach consists of phospholipid fatty acid analysis that is done by Microbial ID, which will provide direct identification any microbes from the presence of lipids. Identified microbes are then compared to mineralogy results from the x-ray diffraction of the core samples to determine if the types of metabolic reactions are consistent with the variation in composition in these analog deposits. If so, it provides intriguing implications for the presence of life in similar Martian deposits.

  11. Microbial redox processes in deep subsurface environments and the potential application of (perchlorate in oil reservoirs

    Directory of Open Access Journals (Sweden)

    Martin G Liebensteiner

    2014-09-01

    Full Text Available The ability of microorganisms to thrive under oxygen-free conditions in subsurface environments relies on the enzymatic reduction of oxidized elements, such as sulfate, ferric iron or CO2, coupled to the oxidation of inorganic or organic compounds. A broad phylogenetic and functional diversity of microorganisms from subsurface environments has been described using isolation-based and advanced molecular ecological techniques. The physiological groups reviewed here comprise iron-, manganese- and nitrate-reducing microorganisms. In the context of recent findings also the potential of chlorate and perchlorate [jointly termed (perchlorate] reduction in oil reservoirs will be discussed. Special attention is given to elevated temperatures that are predominant in the deep subsurface. Microbial reduction of (perchlorate is a thermodynamically favorable redox process, also at high temperature. However, knowledge about (perchlorate reduction at elevated temperatures is still scarce and restricted to members of the Firmicutes and the archaeon Archaeoglobus fulgidus. By analyzing the diversity and phylogenetic distribution of functional genes in (metagenome databases and combining this knowledge with extrapolations to earlier-made physiological observations we speculate on the potential of (perchlorate reduction in the subsurface and more precisely oil fields. In addition, the application of (perchlorate for bioremediation, souring control and microbial enhanced oil recovery are addressed.

  12. 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.

  13. Geophysical Monitoring of Coupled Microbial and Geochemical Processes During Stimulated Subsurface Bioremediation

    International Nuclear Information System (INIS)

    Williams, Kenneth H.; Kemna, Andreas; Wilkins, Michael J.; Druhan, Jennifer L.; Arntzen, Evan V.; N'Guessan, A. Lucie; Long, Philip E.; Hubbard, Susan S.; Banfield, Jillian F.

    2009-01-01

    Understanding how microorganisms alter their physical and chemical environment during bioremediation is hindered by our inability to resolve subsurface microbial activity with high spatial resolution. Here we demonstrate the use of a minimally invasive geophysical technique to monitor stimulated microbial activity during acetate amendment in an aquifer near Rifle, Colorado. During electrical induced polarization (IP) measurements, spatiotemporal variations in the phase response between imposed electric current and the resultant electric field correlated with changes in groundwater geochemistry accompanying stimulated iron and sulfate reduction and sulfide mineral precipitation. The magnitude of the phase response varied with measurement frequency (0.125 and 1 Hz) and was dependent upon the dominant metabolic process. The spectral effect was corroborated using a biostimulated column experiment containing Rifle sediments and groundwater. Fluids and sediments recovered from regions exhibiting an anomalous phase response were enriched in Fe(II), dissolved sulfide, and cell-associated FeS nanoparticles. The accumulation of mineral precipitates and electroactive ions altered the ability of pore fluids to conduct electrical charge, accounting for the anomalous IP response and revealing the usefulness of multifrequency IP measurements for monitoring mineralogical and geochemical changes accompanying stimulated subsurface bioremediation

  14. The Memory Game: Mediational processes in social inclusion

    Directory of Open Access Journals (Sweden)

    Charles Underwood

    2015-02-01

    Full Text Available This article examines mediational processes in educational activities at Projeto Clicar, a program designed to promote the social inclusion of young people living on the streets of São Paulo, Brasil. It presents an ethnographic description of how informal digital and hands-on activities at Projeto Clicar provide for an integrative socio-cultural process, re-situating these children in time and place through the mediation of shared tools and artifacts. This interactive “third space” enables these children to transform their participation in the program’s activities over time, and to re-conceptualize their experience as agentive partners in a community of learners collectively engaged in mastering the tools of sociality. In particular, this ethnographic narrative offers a case study of one child’s interaction with others in learning relatively simple digital games. Using the strategies of participant observation to explore the interactions between children and educators and among the children themselves, this research explores the process of participatory appropriation and suggests alternative modes of relation in the co-construction of inclusionary social and educational activity. // Esta investigación examina los procesos de mediación en las actividades educativas en el Proyecto Clicar, un programa diseñado para promover la inclusión social de los jóvenes que viven en las calles de São Paulo, Brasil. Se presenta una descripción etnográfica de cómo las actividades digitales y prácticas en el Proyecto Clicar prevén un proceso sociocultural de integración, re-situando a estos niños en tiempo y lugar a través de la mediación de herramientas y artefactos compartidos. Este "tercer espacio" interactivo permite a estos niños transformar su participación en las actividades del programa en el tiempo, y re-conceptualizar su experiencia como agentes en una comunidad de aprendizaje que participa colectivamente en la maestría de las

  15. Microbial Protein Production from Candida tropicalis ATCC13803 in a Submerged Batch Fermentation Process

    Directory of Open Access Journals (Sweden)

    Sahar Golaghaiee

    2017-01-01

    Full Text Available Background and Objective: Microbial protein production can resolve one of the major world challenges, i.e. lack of protein sources. Candida tropicalis growth was investigated to specify a medium to reach the highest cell proliferation and protein production.Material and Methods: Fractional factorial design and the index of signal to noise ratio were applied for optimization of microbial protein production. Optimization process was conducted based on the experimental results of Taguchi approach designs. Fermentationwas performed at 25oC and the agitation speed of 300 rpm for 70 h. Ammonium sulfate, iron sulfate, glycine and glucose concentrations were considered as process variables. Optimization of the culture medium composition was conducted in order to obtain the highest cell biomass concentration and protein content. Experiment design was performed based on the Taguchi approach and L-16 orthogonal arrays using Qualitek-4 software.Results and Conclusion: Maximum biomass of 8.72 log (CFU ml-1 was obtained using the optimized medium with 0.3, 0.15, 2 and 80 g l-1 of ammonium sulfate, iron sulfate, glycine and glucose, respectively. Iron sulfate and ammonium sulfate with 41.76% (w w-1 and 35.27% (w w-1 contributions, respectively, were recognized as the main components for cell growth. Glucose and glycine with 17.12% and 5.86% (w w-1 contributions,respectively, also affected cell production. The highest interaction severity index of +54.16% was observed between glycine and glucose while the least one of +0.43% was recorded for ammonium sulfate and glycine. A deviation of 7% between the highestpredicted cell numbers and the experimented count confirms the suitability of the applied statistical method. High protein content of 52.16% (w w-1 as well as low fat and nucleic acids content suggest that Candida tropicalis is a suitable case for commercial processes.Conflict of interest: The authors declare that there is no conflict of interest.

  16. Electrochemically enhanced microbial CO conversion to volatile fatty acids using neutral red as an electron mediator.

    Science.gov (United States)

    Im, Chae Ho; Kim, Changman; Song, Young Eun; Oh, Sang-Eun; Jeon, Byong-Hun; Kim, Jung Rae

    2018-01-01

    Conversion of C1 gas feedstock, including carbon monoxide (CO), into useful platform chemicals has attracted considerable interest in industrial biotechnology. Nevertheless, the low conversion yield and/or growth rate of CO-utilizing microbes make it difficult to develop a C1 gas biorefinery process. The Wood-Ljungdahl pathway which utilize CO is a pathway suffered from insufficient electron supply, in which the conversion can be increased further when an additional electron source like carbohydrate or hydrogen is provided. In this study, electrode-based electron transference using a bioelectrochemical system (BES) was examined to compensate for the insufficient reducing equivalent and increase the production of volatile fatty acids. The BES including neutral red (BES-NR), which facilitated electron transfer between bacteria and electrode, was compared with BES without neutral red and open circuit control. The coulombic efficiency based on the current input to the system and the electrons recovered into VFAs, was significantly higher in BES-NR than the control. These results suggest that the carbon electrode provides a platform to regulate the redox balance for improving the bioconversion of CO, and amending the conventional C1 gas fermentation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Microbial lipase mediated by health beneficial modification of cholesterol and flavors in food products: A review.

    Science.gov (United States)

    Sharma, Ranjana; Sharma, Nivedita

    2017-06-14

    The tremendous need of lipase in varied applications in biotechnological increases its economical value in food and allied industries. Lipase has an impressive number of applications viz. enhancements of flavor in food products (Cheese, butter, alcoholic beverages, milk chocolate and diet control food stuffs), detergent industry in removing oil, grease stain, organic chemical processing, textile industry, oleochemical industry, cosmetic industry and also as therapeutic agents in pharmaceutical industries. This communication extends the frontier of lipase catalyzed benefits to human body by lowering serum cholesterol and enhancement of flavor in different food products. Among all, multiple innovations going on in the field of lipase applications are widening its scope in food industries consistently. Therefore in the present work an effort has been made to explore the utilization of lipase in the field of food product enhancement. Supplementation of food products with lipase results in modification of its physical, chemical and biochemical properties by enhancing its therapeutic activity. Lipases are the most important enzymes used in food industries. They are utilized as industrial catalysts for lipid hydrolysis. Because of lipases hydrolysis nature it is widely exploited to catalyze lipids or fats in different food products and enhancement of food flavors. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  18. SPECIAL ISSUES REGARDING THE MEDIATION PROCESS IN THE COMMERCIAL FIELD

    OpenAIRE

    SEPTIMIU STOICA

    2012-01-01

    The purpose of the research subject to this paper is to find proper solutions for the increase of the volume and efficiency in the field of commercial mediation. Starting from practical remarks, after an analysis of the substance, a new concept is suggested to be included and put into operation, namely the special commercial mediation, and a plead is made for its use in the current activity of alternative dispute resolution. The first major objective of this paper is to demonstrate once again...

  19. Russian Kefir Grains Microbial Composition and Its Changes during Production Process.

    Science.gov (United States)

    Kotova, I B; Cherdyntseva, T A; Netrusov, A I

    2016-01-01

    By combining DGGE-PCR method, classical microbiological analysis and light- and electron microscopic observations, it was found that the composition of microbial communities of central Russia regions kefir grains, starter and kefir drink include bacteria of the genera Lactobacillus, Leuconostoc and Lactococcus, and yeast anamorphs of the genera Saccharomyces, Kazachstania and Gibellulopsis. Fifteen prokaryotic and four eukaryotic pure cultures of microorganisms were isolated and identified from kefir grains. It has been shown that members of the genus Lactobacillus prevailed in kefir grains, whereas strains Leuconostoc pseudomesenteroides and Lactococcus lactis dominated in the final product - kefir drink. Yeasts contained in kefir grains in small amounts have reached a significant number of cells in the process of development of this dairy product. The possibility of reverse cell aggregation has been attempted in a mixed cultivation of all isolated pure cultures, but full formation kefir grains is not yet observed after 1.5 years of observation and reinoculations.

  20. Coupled Transport/Reaction Modelling of Copper Canister Corrosion Aided by Microbial Processes

    Energy Technology Data Exchange (ETDEWEB)

    Jinsong Liu [Royal Institute of Technology, Stockholm (Sweden). Dept. of Chemical Engineering and Technology

    2006-04-15

    Copper canister corrosion is an important issue in the concept of a nuclear fuel repository. Previous studies indicate that the oxygen-free copper canister could hold its integrity for more than 100,000 years in the repository environment. Microbial processes may reduce sulphate to sulphide and considerably increase the amount of sulphides available for corrosion. In this paper, a coupled transport/reaction model is developed to account for the transport of chemical species produced by microbial processes. The corroding agents like sulphide would come not only from the groundwater flowing in a fracture that intersects the canister, but also from the reduction of sulphate near the canister. The reaction of sulphate-reducing bacteria and the transport of sulphide in the bentonite buffer are included in the model. The depth of copper canister corrosion is calculated by the model. With representative 'central values' of the concentrations of sulphate and methane at repository depth at different sites in Fennoscandian Shield the corrosion depth predicted by the model is a few millimetres during 10{sup 5} years. As the concentrations of sulphate and methane are extremely site-specific and future climate changes may significantly influence the groundwater compositions at potential repository sites, sensitivity analyses have been conducted. With a broad perspective of the measured concentrations at different sites in Sweden and in Finland, and some possible mechanisms (like the glacial meltwater intrusion and interglacial seawater intrusion) that may introduce more sulphate into the groundwater at intermediate depths during future climate changes, higher concentrations of either/both sulphate and methane than what is used as the representative 'central' values would be possible. In worst cases. locally, half of the canister thickness could possibly be corroded within 10{sup 5} years.

  1. Comparing mesophilic and thermophilic anaerobic digestion of chicken manure: Microbial community dynamics and process resilience

    International Nuclear Information System (INIS)

    Niu, Qigui; Takemura, Yasuyuki; Kubota, Kengo; Li, Yu-You

    2015-01-01

    Highlights: • Microbial community dynamics and process functional resilience were investigated. • The threshold of TAN in mesophilic reactor was higher than the thermophilic reactor. • The recoverable archaeal community dynamic sustained the process resilience. • Methanosarcina was more sensitive than Methanoculleus on ammonia inhibition. • TAN and FA effects the dynamic of hydrolytic and acidogenic bacteria obviously. - Abstract: While methane fermentation is considered as the most successful bioenergy treatment for chicken manure, the relationship between operational performance and the dynamic transition of archaeal and bacterial communities remains poorly understood. Two continuous stirred-tank reactors were investigated under thermophilic and mesophilic conditions feeding with 10%TS. The tolerance of thermophilic reactor on total ammonia nitrogen (TAN) was found to be 8000 mg/L with free ammonia (FA) 2000 mg/L compared to 16,000 mg/L (FA1500 mg/L) of mesophilic reactor. Biomethane production was 0.29 L/gV S in in the steady stage and decreased following TAN increase. After serious inhibition, the mesophilic reactor was recovered successfully by dilution and washing stratagem compared to the unrecoverable of thermophilic reactor. The relationship between the microbial community structure, the bioreactor performance and inhibitors such as TAN, FA, and volatile fatty acid was evaluated by canonical correspondence analysis. The performance of methanogenic activity and substrate removal efficiency were changed significantly correlating with the community evenness and phylogenetic structure. The resilient archaeal community was found even after serious inhibition in both reactors. Obvious dynamics of bacterial communities were observed in acidogenic and hydrolytic functional bacteria following TAN variation in the different stages

  2. The large-scale process of microbial carbonate precipitation for nickel remediation from an industrial soil.

    Science.gov (United States)

    Zhu, Xuejiao; Li, Weila; Zhan, Lu; Huang, Minsheng; Zhang, Qiuzhuo; Achal, Varenyam

    2016-12-01

    Microbial carbonate precipitation is known as an efficient process for the remediation of heavy metals from contaminated soils. In the present study, a urease positive bacterial isolate, identified as Bacillus cereus NS4 through 16S rDNA sequencing, was utilized on a large scale to remove nickel from industrial soil contaminated by the battery industry. The soil was highly contaminated with an initial total nickel concentration of approximately 900 mg kg -1 . The soluble-exchangeable fraction was reduced to 38 mg kg -1 after treatment. The primary objective of metal stabilization was achieved by reducing the bioavailability through immobilizing the nickel in the urease-driven carbonate precipitation. The nickel removal in the soils contributed to the transformation of nickel from mobile species into stable biominerals identified as calcite, vaterite, aragonite and nickelous carbonate when analyzed under XRD. It was proven that during precipitation of calcite, Ni 2+ with an ion radius close to Ca 2+ was incorporated into the CaCO 3 crystal. The biominerals were also characterized by using SEM-EDS to observe the crystal shape and Raman-FTIR spectroscopy to predict responsible bonding during bioremediation with respect to Ni immobilization. The electronic structure and chemical-state information of the detected elements during MICP bioremediation process was studied by XPS. This is the first study in which microbial carbonate precipitation was used for the large-scale remediation of metal-contaminated industrial soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Coupled Transport/Reaction Modelling of Copper Canister Corrosion Aided by Microbial Processes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinsong [Royal Institute of Technology, Stockholm (Sweden). Dept. of Chemical Engineering and Technology

    2006-04-15

    Copper canister corrosion is an important issue in the concept of a nuclear fuel repository. Previous studies indicate that the oxygen-free copper canister could hold its integrity for more than 100,000 years in the repository environment. Microbial processes may reduce sulphate to sulphide and considerably increase the amount of sulphides available for corrosion. In this paper, a coupled transport/reaction model is developed to account for the transport of chemical species produced by microbial processes. The corroding agents like sulphide would come not only from the groundwater flowing in a fracture that intersects the canister, but also from the reduction of sulphate near the canister. The reaction of sulphate-reducing bacteria and the transport of sulphide in the bentonite buffer are included in the model. The depth of copper canister corrosion is calculated by the model. With representative 'central values' of the concentrations of sulphate and methane at repository depth at different sites in Fennoscandian Shield the corrosion depth predicted by the model is a few millimetres during 10{sup 5} years. As the concentrations of sulphate and methane are extremely site-specific and future climate changes may significantly influence the groundwater compositions at potential repository sites, sensitivity analyses have been conducted. With a broad perspective of the measured concentrations at different sites in Sweden and in Finland, and some possible mechanisms (like the glacial meltwater intrusion and interglacial seawater intrusion) that may introduce more sulphate into the groundwater at intermediate depths during future climate changes, higher concentrations of either/both sulphate and methane than what is used as the representative 'central' values would be possible. In worst cases. locally, half of the canister thickness could possibly be corroded within 10{sup 5} years.

  4. Coupled Transport/Reaction Modelling of Copper Canister Corrosion Aided by Microbial Processes

    International Nuclear Information System (INIS)

    Jinsong Liu

    2006-04-01

    Copper canister corrosion is an important issue in the concept of a nuclear fuel repository. Previous studies indicate that the oxygen-free copper canister could hold its integrity for more than 100,000 years in the repository environment. Microbial processes may reduce sulphate to sulphide and considerably increase the amount of sulphides available for corrosion. In this paper, a coupled transport/reaction model is developed to account for the transport of chemical species produced by microbial processes. The corroding agents like sulphide would come not only from the groundwater flowing in a fracture that intersects the canister, but also from the reduction of sulphate near the canister. The reaction of sulphate-reducing bacteria and the transport of sulphide in the bentonite buffer are included in the model. The depth of copper canister corrosion is calculated by the model. With representative 'central values' of the concentrations of sulphate and methane at repository depth at different sites in Fennoscandian Shield the corrosion depth predicted by the model is a few millimetres during 10 5 years. As the concentrations of sulphate and methane are extremely site-specific and future climate changes may significantly influence the groundwater compositions at potential repository sites, sensitivity analyses have been conducted. With a broad perspective of the measured concentrations at different sites in Sweden and in Finland, and some possible mechanisms (like the glacial meltwater intrusion and interglacial seawater intrusion) that may introduce more sulphate into the groundwater at intermediate depths during future climate changes, higher concentrations of either/both sulphate and methane than what is used as the representative 'central' values would be possible. In worst cases. locally, half of the canister thickness could possibly be corroded within 10 5 years

  5. Comparing mesophilic and thermophilic anaerobic digestion of chicken manure: Microbial community dynamics and process resilience

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Qigui; Takemura, Yasuyuki; Kubota, Kengo [Department of Civil and Environmental Engineering, Graduate School of Engineering Tohoku University, 6-6-06 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Li, Yu-You, E-mail: yyli@epl1.civil.tohoku.ac.jp [Department of Civil and Environmental Engineering, Graduate School of Engineering Tohoku University, 6-6-06 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Xi’an University of Architecture and Technology, Xi’an (China)

    2015-09-15

    Highlights: • Microbial community dynamics and process functional resilience were investigated. • The threshold of TAN in mesophilic reactor was higher than the thermophilic reactor. • The recoverable archaeal community dynamic sustained the process resilience. • Methanosarcina was more sensitive than Methanoculleus on ammonia inhibition. • TAN and FA effects the dynamic of hydrolytic and acidogenic bacteria obviously. - Abstract: While methane fermentation is considered as the most successful bioenergy treatment for chicken manure, the relationship between operational performance and the dynamic transition of archaeal and bacterial communities remains poorly understood. Two continuous stirred-tank reactors were investigated under thermophilic and mesophilic conditions feeding with 10%TS. The tolerance of thermophilic reactor on total ammonia nitrogen (TAN) was found to be 8000 mg/L with free ammonia (FA) 2000 mg/L compared to 16,000 mg/L (FA1500 mg/L) of mesophilic reactor. Biomethane production was 0.29 L/gV S{sub in} in the steady stage and decreased following TAN increase. After serious inhibition, the mesophilic reactor was recovered successfully by dilution and washing stratagem compared to the unrecoverable of thermophilic reactor. The relationship between the microbial community structure, the bioreactor performance and inhibitors such as TAN, FA, and volatile fatty acid was evaluated by canonical correspondence analysis. The performance of methanogenic activity and substrate removal efficiency were changed significantly correlating with the community evenness and phylogenetic structure. The resilient archaeal community was found even after serious inhibition in both reactors. Obvious dynamics of bacterial communities were observed in acidogenic and hydrolytic functional bacteria following TAN variation in the different stages.

  6. Microbial dynamics during industrial rearing, processing, and storage of the tropical house cricket (Gryllodes sigillatus) for human consumption.

    Science.gov (United States)

    Vandeweyer, Dries; Wynants, Enya; Crauwels, Sam; Verreth, Christel; Viaene, Nikolaas; Claes, Johan; Lievens, Bart; Van Campenhout, Leen

    2018-04-06

    In this study, the microbiota during industrial rearing, processing, and storage of the edible tropical house cricket, Gryllodes sigillatus , was investigated. To this end, samples were analyzed of the cricket feed, before feeding as well as taken from the cages, and the crickets during rearing, after harvest, and after processing into frozen, oven-dried, and smoked and subsequently oven-dried end products. Although the feed contained lower microbial numbers than the crickets, both were dominated by the same species-level operational taxonomic units as determined by Illumina Miseq sequencing. They corresponded, among others, to members of Porphyromonadaceae, Fusobacterium , Parabacteroides and Erwinia The harvested crickets contained high microbial numbers, but none of the investigated food pathogens Salmonella spp., Listeria monocytogenes , Bacillus cereus , and coagulase-positive staphylococci. However, some possible mycotoxin-producing fungi were isolated from the crickets. A post-harvest heat treatment, shortly boiling the crickets, reduced microbial numbers, but an endospore load of 2.4 log cfu/g remained. After processing, an increase in microbial counts was observed for dried and smoked plus dried crickets. Additionally, in the smoked plus dried crickets, a high abundance of a Bacillus sp. was observed. Considering the possible occurrence of food-pathogenic species from this genus, it is advised to apply a heat treatment which is sufficient to eliminate spores. Nevertheless, the microbial numbers remained constant over a six-month storage period, frozen (frozen end product) or at ambient temperature (oven-dried and smoked plus dried end products). Importance. The need for sustainable protein sources has led to the emergence of a new food sector, producing and processing edible insects into foods. However, insight into the microbial quality of this new food and into the microbial dynamics during rearing, processing and storage of edible insects is still

  7. Mechanistic and kinetic aspects of microbial inactivation in food irradiation processes

    International Nuclear Information System (INIS)

    Tukenmez, I.

    2004-01-01

    Full text: A proper reaction mechanism was searched by analyzing the inactivation processes of microorganisms during food irradiation by ionizing radiation. By employing transition-state theory, it was assumed that the overall inactivation process involves a reversible sub-lethal stress and repair reactions to form reversibly injured cell or sensitized cell, which then undergoes irreversible injury leading to dead cell. A shoulder in low dose range in survival kinetics was associated with the repair process. Depending on the postulated mechanism, kinetic model equations were derived. The kinetics of cell inactivation by irradiation was expressed as depending on irradiation dose. By using experimental data in the developed model the inactivation parameters including threshold dose, radiation yield, decimal reduction dose and minimum sterilization dose were evaluated and microbial inactivation by irradiation was simulated by using the numerical values of the parameters. Developed model and model parameters may be used for the process control and the assessment of product quality in radiation preservation of food

  8. Do attentional capacities and processing speed mediate the effect of age on executive functioning?

    Science.gov (United States)

    Gilsoul, Jessica; Simon, Jessica; Hogge, Michaël; Collette, Fabienne

    2018-02-06

    The executive processes are well known to decline with age, and similar data also exists for attentional capacities and processing speed. Therefore, we investigated whether these two last nonexecutive variables would mediate the effect of age on executive functions (inhibition, shifting, updating, and dual-task coordination). We administered a large battery of executive, attentional and processing speed tasks to 104 young and 71 older people, and we performed mediation analyses with variables showing a significant age effect. All executive and processing speed measures showed age-related effects while only the visual scanning task performance (selective attention) was explained by age when controlled for gender and educational level. Regarding mediation analyses, visual scanning partially mediated the age effect on updating while processing speed partially mediated the age effect on shifting, updating and dual-task coordination. In a more exploratory way, inhibition was also found to partially mediate the effect of age on the three other executive functions. Attention did not greatly influence executive functioning in aging while, in agreement with the literature, processing speed seems to be a major mediator of the age effect on these processes. Interestingly, the global pattern of results seems also to indicate an influence of inhibition but further studies are needed to confirm the role of that variable as a mediator and its relative importance by comparison with processing speed.

  9. Silver nanoparticles uptake by salt marsh plants - Implications for phytoremediation processes and effects in microbial community dynamics.

    Science.gov (United States)

    Fernandes, Joana P; Mucha, Ana P; Francisco, Telmo; Gomes, Carlos Rocha; Almeida, C Marisa R

    2017-06-15

    This study investigated the uptake of silver nanoparticles (AgNPs) by a salt marsh plant, Phragmites australis, as well as AgNPs effects on rhizospheric microbial community, evaluating the implications for phytoremediation processes. Experiments were carried out with elutriate solution doped with Ag, either in ionic form or in NP form. Metal uptake was evaluated in plant tissues, elutriate solutions and sediments (by AAS) and microbial community was characterized in terms of bacterial community structure (evaluated by ARISA). Results showed Ag accumulation but only in plant belowground tissues and only in the absence of rhizosediment, the presence of sediment reducing Ag availability. But in plant roots Ag accumulation was higher when Ag was in NP form. Multivariate analysis of ARISA profiles showed significant effect of the absence/presence of Ag either in ionic or NP form on microbial community structure, although without significant differences among bacterial richness and diversity. Overall, P. australis can be useful for phytoremediation of medium contaminated with Ag, including with AgNPs. However, the presence of Ag in either forms affected the microbial community structure, which may cause disturbances in ecosystems function and compromise phytoremediation processes. Such considerations need to be address regarding environmental management strategies applied to the very important estuarine areas. The form in which the metal was added affected metal uptake by Phragmites australis and rhizosediment microbial community structure, which can affect phytoremediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. A novel process for synthesis of spherical nanocellulose by controlled hydrolysis of microcrystalline cellulose using anaerobic microbial consortium.

    Science.gov (United States)

    Satyamurthy, P; Vigneshwaran, N

    2013-01-10

    Degradation of cellulose by anaerobic microbial consortium is brought about either by an exocellular process or by secretion of extracellular enzymes. In this work, a novel route for synthesis of nanocellulose is described where in an anaerobic microbial consortium enriched for cellulase producers is used for hydrolysis. Microcrystalline cellulose derived from cotton fibers was subjected to controlled hydrolysis by the anaerobic microbial consortium and the resultant nanocellulose was purified by differential centrifugation technique. The nanocellulose had a bimodal size distribution (43±13 and 119±9 nm) as revealed by atomic force microscopy. A maximum nanocellulose yield of 12.3% was achieved in a span of 7 days. While the conventional process of nanocellulose preparation using 63.5% (w/w) sulfuric acid resulted in the formation of whisker shaped nanocellulose with surface modified by sulfation, controlled hydrolysis by anaerobic microbial consortium yielded spherical nanocellulose also referred to as nano crystalline cellulose (NCC) without any surface modification as evidenced from Fourier transform infrared spectroscopy. Also, it scores over chemo-mechanical production of nanofibrillated cellulose by consuming less energy due to enzyme (cellulase) assisted catalysis. This implies the scope for use of microbial prepared nanocellulose in drug delivery and bio-medical applications requiring bio-compatibility. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Isolation of microbial native Stumps with cellulolytic activity of a compost process

    International Nuclear Information System (INIS)

    Jaramillo G, Marisol; Ruiz V Orlando Simon; Yepes P, Maria del Socorro; Montoya C, Olga Ines

    2003-01-01

    The isolation, selection adaptation and handling of native microorganisms coming from organic waste are an alternative to avoid the accumulation and the lack of the proper use of these undesirable materials. This organic waste is a source for obtaining microbial strains, which are potentially producers of Industrial enzymes and, at the same time, it works as substrate so that these organisms can transform it into compost or organic manure. In this work, 39 native strains of microorganisms with potential cellulolytic activity coming from the organic waste of the urban and rural sector, from the Compost Plant of Marinilla Antioquia) municipality, were isolated, evaluated and purified. The waste was previously selected and then submitted to an aerobic degradation or compost. The microbial strains were isolated in a selective medium with carboxymethyl cellulose (CMC), of the phases mesophile, termophile, cooling and maturation of the compost process. Eighty-two percent (82%)of the obtained colonies were identified, in principle as Bacillus, because of their morphology and their reaction to the Gram coloration. The fungi population was seen only during the cooling phase. Then, the potential cellulolytic activity was evaluated qualitatively in a solid medium with the Congo Red coloration, with which the Beta-endoglucanase activity was evaluated through the formation of clarified zones. Such staining was applied in two mediums with CMC with and without glucose It was observed that 33.3% of the isolated organisms produced the enzyme In both mediums; however, 25.6% of microorganisms did not show the production of this enzyme, and only 15.8% did not require the inducers to produce it

  12. Detection of microbial biofilms on food processing surfaces: hyperspectral fluorescence imaging study

    Science.gov (United States)

    Jun, Won; Kim, Moon S.; Chao, Kaunglin; Lefcourt, Alan M.; Roberts, Michael S.; McNaughton, James L.

    2009-05-01

    We used a portable hyperspectral fluorescence imaging system to evaluate biofilm formations on four types of food processing surface materials including stainless steel, polypropylene used for cutting boards, and household counter top materials such as formica and granite. The objective of this investigation was to determine a minimal number of spectral bands suitable to differentiate microbial biofilm formation from the four background materials typically used during food processing. Ultimately, the resultant spectral information will be used in development of handheld portable imaging devices that can be used as visual aid tools for sanitation and safety inspection (microbial contamination) of the food processing surfaces. Pathogenic E. coli O157:H7 and Salmonella cells were grown in low strength M9 minimal medium on various surfaces at 22 +/- 2 °C for 2 days for biofilm formation. Biofilm autofluorescence under UV excitation (320 to 400 nm) obtained by hyperspectral fluorescence imaging system showed broad emissions in the blue-green regions of the spectrum with emission maxima at approximately 480 nm for both E. coli O157:H7 and Salmonella biofilms. Fluorescence images at 480 nm revealed that for background materials with near-uniform fluorescence responses such as stainless steel and formica cutting board, regardless of the background intensity, biofilm formation can be distinguished. This suggested that a broad spectral band in the blue-green regions can be used for handheld imaging devices for sanitation inspection of stainless, cutting board, and formica surfaces. The non-uniform fluorescence responses of granite make distinctions between biofilm and background difficult. To further investigate potential detection of the biofilm formations on granite surfaces with multispectral approaches, principal component analysis (PCA) was performed using the hyperspectral fluorescence image data. The resultant PCA score images revealed distinct contrast between

  13. Computer-Mediated Collaborative Projects: Processes for Enhancing Group Development

    Science.gov (United States)

    Dupin-Bryant, Pamela A.

    2008-01-01

    Groups are a fundamental part of the business world. Yet, as companies continue to expand internationally, a major challenge lies in promoting effective communication among employees who work in varying time zones. Global expansion often requires group collaboration through computer systems. Computer-mediated groups lead to different communicative…

  14. Relationship of microbial processes to the fate and behavior of transuranic elements in soils, plants, and animals

    International Nuclear Information System (INIS)

    Wildung, R.E.; Garland, T.R.

    1980-01-01

    Soil physicochemical and microbial processes influence the long-term solubility, form, and bioavailability of plutonium and other transuranic elements important in the nuclear fuel cycle. Consideration is given to the chemistry/microbiology of the transuranic elements in soil, emphasizing possible organic complexation reactions in soils and plants and the relationship of these phenomena to gastrointestinal absorption

  15. How Can Research Mediators Better Mediate?: The Importance of Inward-Looking Processes

    Science.gov (United States)

    Shaw, Jessica

    2018-01-01

    Science can provide empirically-informed strategies and resources to inform and improve policy and practice, though all too often science, policy, and practice operate independently from one another. Research mediators play a critical role by attempting to connect these different worlds. This practice paper presents lessons learned and…

  16. Microbial-processing of fruit and vegetable wastes for production of vital enzymes and organic acids: Biotechnology and scopes.

    Science.gov (United States)

    Panda, Sandeep K; Mishra, Swati S; Kayitesi, Eugenie; Ray, Ramesh C

    2016-04-01

    Wastes generated from fruits and vegetables are organic in nature and contribute a major share in soil and water pollution. Also, green house gas emission caused by fruit and vegetable wastes (FVWs) is a matter of serious environmental concern. This review addresses the developments over the last one decade on microbial processing technologies for production of enzymes and organic acids from FVWs. The advances in genetic engineering for improvement of microbial strains in order to enhance the production of the value added bio-products as well as the concept of zero-waste economy have been briefly discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Microbial export of lactic and 3-hydroxypropanoic acid : implications for industrial fermentation processes

    NARCIS (Netherlands)

    van Maris, AJA; Konings, WN; Pronk, Jack T.; Dijken, J.P. van

    2004-01-01

    Lactic acid and 3-hydroxypropanoic acid are industrially relevant microbial products. This paper reviews the current knowledge on export of these compounds from microbial cells and presents a theoretical analysis of the bioenergetics of different export mechanisms. It is concluded that export can be

  18. Recent advances in molecular techniques to study microbial communities in food-associated matrices and processes

    NARCIS (Netherlands)

    Justé, A.; Thomma, B.P.H.J.; Lievens, B.

    2008-01-01

    In the last two decades major changes have occurred in how microbial ecologists study microbial communities. Limitations associated with traditional culture-based methods have pushed for the development of culture-independent techniques, which are primarily based on the analysis of nucleic acids.

  19. Deciphering the microbial ecology in bio- gas reactors for optimizing the anaerobic digestion process

    DEFF Research Database (Denmark)

    Zhu, Xinyu

    of the basic microbial metabolism and ecology, methanogenic microbial communities were enriched in a lab-scale continuous stirred-tank reactor (CSTR) fed with synthetic feedstocks. In the experiment, the substrates used were stepwise simplified (i.e. polysaccharide, monosaccharide, short chain fatty acids...

  20. Effects of experimental drought on microbial processes in two temperate heathlands at contrasting water conditions

    DEFF Research Database (Denmark)

    Jensen, K.D.; Beier, C.; Michelsen, A.

    2003-01-01

    by a 27% reduced below ground CO(2) emission, and reduced microbial and soil solution carbon (C) and nitrogen (N) levels. In contrast, microbial activity at the wetter UK site seemed to benefit from the drought as indicated by a 22% increase in below ground CO(2) emission caused by the drought treatment...

  1. Microbial Performance of Food Safety Control and Assurance Activities in a Fresh Produce Processing Sector Measured Using a Microbial Assessment Scheme and Statistical Modeling

    DEFF Research Database (Denmark)

    Njage, Patrick Murigu Kamau; Sawe, Chemutai Tonui; Onyango, Cecilia Moraa

    2017-01-01

    assessment scheme and statistical modeling were used to systematically assess the microbial performance of core control and assurance activities in five Kenyan fresh produce processing and export companies. Generalized linear mixed models and correlated random-effects joint models for multivariate clustered...... the maximum safety level for environmental samples. Escherichia coli was detected in five of the six CSLs, including the final product. Among the processing-environment samples, the hand or glove swabs of personnel revealed a higher level of predicted contamination with E. coli, and 80% of the factories were...... of contamination with coliforms in water at the inlet than in the final rinse water. Four (80%) of the five assessed processors had poor to unacceptable counts of Enterobacteriaceae on processing surfaces. Personnel-, equipment-, and product-related hygiene measures to improve the performance of preventive...

  2. The Validation of Vapor Phase Hydrogen Peroxide Microbial Reduction for Planetary Protection and a Proposed Vacuum Process Specification

    Science.gov (United States)

    Chung, Shirley; Barengoltz, Jack; Kern, Roger; Koukol, Robert; Cash, Howard

    2006-01-01

    The Jet Propulsion Laboratory, in conjunction with the NASA Planetary Protection Officer, has selected the vapor phase hydrogen peroxide sterilization process for continued development as a NASA approved sterilization technique for spacecraft subsystems and systems. The goal is to include this technique, with an appropriate specification, in NPR 8020.12C as a low temperature complementary technique to the dry heat sterilization process.To meet microbial reduction requirements for all Mars in-situ life detection and sample return missions, various planetary spacecraft subsystems will have to be exposed to a qualified sterilization process. This process could be the elevated temperature dry heat sterilization process (115 C for 40 hours) which was used to sterilize the Viking lander spacecraft. However, with utilization of such elements as highly sophisticated electronics and sensors in modern spacecraft, this process presents significant materials challenges and is thus an undesirable bioburden reduction method to design engineers. The objective of this work is to introduce vapor hydrogen peroxide (VHP) as an alternative to dry heat microbial reduction to meet planetary protection requirements.The VHP process is widely used by the medical industry to sterilize surgical instruments and biomedical devices, but high doses of VHP may degrade the performance of flight hardware, or compromise material properties. Our goal for this study was to determine the minimum VHP process conditions to achieve microbial reduction levels acceptable for planetary protection.

  3. Microbial Diseases in the Teaching-learning Process of Deaf People: A Possible Dialogue

    Directory of Open Access Journals (Sweden)

    Roberta Silva Rizzo

    2014-09-01

    Full Text Available Special Education remains a major challenge in society. Thus, many methodologies and didactic-pedagogic resources have been deployed in order to further the teaching and learning process in different subjects, with emphasis on Science teaching. By understanding the importance of diseases caused by microorganisms, the game titled “Knowing the unseen world - challenging signal” was conceived as a didactic proposal to inform and enlighten deaf students from Elementary School on this subject, applying visual tools. Therefore, its construction took the National Curriculum Parameters (NCP for Natural Sciences as a guiding, and the development of the graphic art consisted of simple and low cost materials. As a result, it was obtained a teaching resource with signs of LIBRAS that meets the objectives and contents that addresses of the three main themes of the NCPs. So, this is a suggestion to work the microbial content in a less abstract and more attractive form to deaf students, providing an opportunity to address issues specified in science curriculum in order to support the teaching-learning process focused on scientific literacy and the appropriation of knowledge related to the development of skills and abilities necessary to the current society.

  4. Spatial nitrifications of microbial processes during composting of swine, cow and chicken manure

    Science.gov (United States)

    Wang, Ke; Li, Weiguang; Li, Xiangkun; Ren, Nanqi

    2015-10-01

    Composting is a widely-used method to recycle the nutrients in livestock manure for agriculture. The spatial stratifications of microbial processes inside the manure particle that determine organic and nitrogen transformation are virtually unclear. Here, we show the evolution of the interior microenvironment of swine, cow and chicken manure by using microelectrodes during forced-aeration composting. Composting has generally been regarded as an aerobic bioprocess, however, the long-existing of a large anoxic zone inside these manures was confirmed during the active phase in this study. The profile of the oxidation-reduction potential dramatically decreased first and then gradually increased. The spatial difference in the ammonia concentration was not significant, but nitrate concentration continuously decreased with depth. The anoxic condition within the manure particle was demonstrated to be a primary cause of the severe ammonia emission and the long composting period. These founding provided a new insight toward “aerobic” composting process and a sound foundation for the development of efficient composting technology.

  5. Effect of cloacal plugging on microbial recovery from partially processed broilers.

    Science.gov (United States)

    Musgrove, M T; Cason, J A; Fletcher, D L; Stern, N J; Cox, N A; Bailey, J S

    1997-03-01

    Experiments were performed to test the contribution of bacteria contained in the intestinal tract of broilers at the beginning of processing to counts on the exterior of modified New York-dressed carcasses. Thirty-two birds were processed for each of seven replications. Within each replication, batches of four birds were electrocuted, scalded, and picked, with batches alternating between treatment and control groups. Treated birds were cloacally plugged with rayon fiber tampons prior to electrocution to prevent escape of intestinal contents during scalding and picking. Control birds were processed in the same manner, except that cloacal plugs were inserted immediately after defeathering to reduce escape of intestinal contents during sampling. Gram-negative enteric bacteria and Campylobacter spp. were enumerated on carcasses by whole carcass rinse procedure and in cecal contents. Counts were converted to log10 and subjected to analysis of variance. Cecal levels of Gram-negative enterics were significantly higher for plugged birds, but there was not a significant difference between levels of cecal Campylobacter spp. between treatment groups. Plugging before electrocution resulted in significantly lower levels (2.5 vs 3.0 log10 cfu/mL) of Campylobacter spp. and Gram-negative enteric bacteria (3.0 vs 3.4 log10 cfu/mL) in carcass rinses of treatment birds than in those of controls. All carcasses were positive for Gram-negative enterics. Cloacal plugging resulted in significantly lower incidence of Campylobacter spp. carcass contamination as determined by chi-square. Intestinal carriage of both campylobacters and Gram-negative enteric bacteria appears to influence the microbial quality of the carcass during processing.

  6. Bio-Electron-Fenton (BEF) process driven by microbial fuel cells for triphenyltin chloride (TPTC) degradation

    Energy Technology Data Exchange (ETDEWEB)

    Yong, Xiao-Yu; Gu, Dong-Yan; Wu, Yuan-Dong [College of Biotechnology and Pharmaceutical Engineering, Nanjing TECH University, Nanjing 211816 (China); Bioenergy Research Institute, Nanjing TECH University, Nanjing 211816 (China); Yan, Zhi-Ying [Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology, Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Science, Chengdu 610041 (China); Zhou, Jun; Wu, Xia-Yuan [College of Biotechnology and Pharmaceutical Engineering, Nanjing TECH University, Nanjing 211816 (China); Bioenergy Research Institute, Nanjing TECH University, Nanjing 211816 (China); Wei, Ping [College of Biotechnology and Pharmaceutical Engineering, Nanjing TECH University, Nanjing 211816 (China); Jia, Hong-Hua [College of Biotechnology and Pharmaceutical Engineering, Nanjing TECH University, Nanjing 211816 (China); Bioenergy Research Institute, Nanjing TECH University, Nanjing 211816 (China); Zheng, Tao, E-mail: zhengtao@ms.giec.ac.cn [Guangzhou Institute of Energy Conversion, Chinese Academy of Science, Nengyuan Road, Guangzhou 510640 (China); Yong, Yang-Chun, E-mail: ycyong@ujs.edu.cn [Biofuels Institute, School of the Environment, Jiangsu University, Zhenjiang 212013 (China); Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2017-02-15

    Graphical abstract: Schematic diagram of the Bio-Electron-Fenton (BEF) process for TPTC degradation. - Highlights: • A Bio-Electro-Fenton process was performed for TPTC degradation. • TPTC removal efficiency achieved 78.32 ± 2.07% within 100 h. • The TPTC degradation rate (0.775 ± 0.021 μmol L{sup −1} h{sup −1}) was much higher than previous reports. - Abstract: The intensive use of triphenyltin chloride (TPTC) has caused serious environmental pollution. In this study, an effective method for TPTC degradation was proposed based on the Bio-Electron-Fenton process in microbial fuel cells (MFCs). The maximum voltage of the MFC with graphite felt as electrode was 278.47% higher than that of carbon cloth. The electricity generated by MFC can be used for in situ generation of H{sub 2}O{sub 2} to a maximum of 135.96 μmol L{sup −1} at the Fe@Fe{sub 2}O{sub 3(*)}/graphite felt composite cathode, which further reacted with leached Fe{sup 2+} to produce hydroxyl radicals. While 100 μmol L{sup −1} TPTC was added to the cathodic chamber, the degradation efficiency of TPTC reached 78.32 ± 2.07%, with a rate of 0.775 ± 0.021 μmol L{sup −1} h{sup −1}. This Bio-Electron-Fenton driving TPTC degradation might involve in Sn−C bonds breaking and the main process is probably a stepwise dephenylation until the formation of inorganic tin and CO{sub 2}. This study provides an energy saving and efficient approach for TPTC degradation.

  7. Bio-Electron-Fenton (BEF) process driven by microbial fuel cells for triphenyltin chloride (TPTC) degradation

    International Nuclear Information System (INIS)

    Yong, Xiao-Yu; Gu, Dong-Yan; Wu, Yuan-Dong; Yan, Zhi-Ying; Zhou, Jun; Wu, Xia-Yuan; Wei, Ping; Jia, Hong-Hua; Zheng, Tao; Yong, Yang-Chun

    2017-01-01

    Graphical abstract: Schematic diagram of the Bio-Electron-Fenton (BEF) process for TPTC degradation. - Highlights: • A Bio-Electro-Fenton process was performed for TPTC degradation. • TPTC removal efficiency achieved 78.32 ± 2.07% within 100 h. • The TPTC degradation rate (0.775 ± 0.021 μmol L"−"1 h"−"1) was much higher than previous reports. - Abstract: The intensive use of triphenyltin chloride (TPTC) has caused serious environmental pollution. In this study, an effective method for TPTC degradation was proposed based on the Bio-Electron-Fenton process in microbial fuel cells (MFCs). The maximum voltage of the MFC with graphite felt as electrode was 278.47% higher than that of carbon cloth. The electricity generated by MFC can be used for in situ generation of H_2O_2 to a maximum of 135.96 μmol L"−"1 at the Fe@Fe_2O_3_(_*_)/graphite felt composite cathode, which further reacted with leached Fe"2"+ to produce hydroxyl radicals. While 100 μmol L"−"1 TPTC was added to the cathodic chamber, the degradation efficiency of TPTC reached 78.32 ± 2.07%, with a rate of 0.775 ± 0.021 μmol L"−"1 h"−"1. This Bio-Electron-Fenton driving TPTC degradation might involve in Sn−C bonds breaking and the main process is probably a stepwise dephenylation until the formation of inorganic tin and CO_2. This study provides an energy saving and efficient approach for TPTC degradation.

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

    Directory of Open Access Journals (Sweden)

    B. Orcutt

    2008-11-01

    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.

  9. Microbial biosensors

    International Nuclear Information System (INIS)

    Le Yu; Chen, Wilfred; Mulchandani, Ashok

    2006-01-01

    A microbial biosensor is an analytical device that couples microorganisms with a transducer to enable rapid, accurate and sensitive detection of target analytes in fields as diverse as medicine, environmental monitoring, defense, food processing and safety. The earlier microbial biosensors used the respiratory and metabolic functions of the microorganisms to detect a substance that is either a substrate or an inhibitor of these processes. Recently, genetically engineered microorganisms based on fusing of the lux, gfp or lacZ gene reporters to an inducible gene promoter have been widely applied to assay toxicity and bioavailability. This paper reviews the recent trends in the development and application of microbial biosensors. Current advances and prospective future direction in developing microbial biosensor have also been discussed

  10. Tracing the Policy Mediation Process in the Implementation of a Change in the Life Sciences Curriculum

    Science.gov (United States)

    Singh-Pillay, Asheena; Alant, Busisiwe

    2015-01-01

    This paper accounts for the enacted realities of curriculum reform in South Africa, in particular the mediation of curriculum change. Curriculum implementation is viewed as a complex networked process of transforming or mediating policy into classroom practice. The fact that curriculum implementation is seen as problematic requires attention for…

  11. Effect of sous vide processing on physicochemical, ultrastructural, microbial and sensory changes in vacuum packaged chicken sausages.

    Science.gov (United States)

    Naveena, B M; Khansole, Panjab S; Shashi Kumar, M; Krishnaiah, N; Kulkarni, Vinayak V; Deepak, S J

    2017-01-01

    The processing of sous vide chicken sausages was optimized under vacuum packaging condition and cooking at 100 ℃ for 30 min (SV30), 60 min (SV60) and 120 min (SV120) and compared with aerobically cooked control at 100 ℃ for 30 min. Sous vide processing of chicken sausages (SV30) produced higher (p emulsion ultra-structure due to SV30 processing relative to control sausages. Sous vide processing of chicken sausages enriched with rosemary diterpene phenols retained the freshness and quality up to 120 days during storage at 4 ± 1 ℃ relative to control sausages that were spoiled on 20th day. Lipid oxidation and microbial growth remained below the spoilage levels for all the SV-processed sausages throughout the storage and addition of rosemary diterpene mixture at 0.02% v/w reduced the microbial growth and improved (p < 0.05) the sensory attributes. Our results demonstrate that sous vide processing minimizes lipid oxidation and microbial growth of chicken sausages with improved product quality and shelf-life at 4 ± 1 ℃. © The Author(s) 2016.

  12. Microbial and Sensory Effects of Combined High Hydrostatic Pressure and Dense Phase Carbon Dioxide Process on Feijoa Puree.

    Science.gov (United States)

    Duong, Trang; Balaban, Murat; Perera, Conrad; Bi, Xiufang

    2015-11-01

    High hydrostatic pressure (HHP) is used for microbial inactivation in foods. Addition of carbon dioxide (CO2) to HHP can improve microbial and enzyme inactivation. This study investigated microbial effects of combined HHP and CO2 on Escherichia coli, Bacillus subtilis, and Saccharomyces cerevisiae, and evaluated sensory attributes of treated feijoa fruit puree (pH 3.2). Microorganisms in their growth media and feijoa puree were treated with HHP alone (HHP), or saturated with CO2 at 1 atm (HHPcarb), or 0.4%w/w of CO2 was injected into the package (HHPcarb+CO2). Microbial samples were processed at 200 to 400 MPa, 25 °C, 2 to 6 min. Feijoa samples were processed at 600 MPa, 20 °C, 5 min, then served with and without added sucrose (10%w/w). Treated samples were analyzed for microbial viability and sensory evaluation. Addition of CO2 enhanced microbial inactivation of HHP from 1.7-log to 4.3-log reduction in E. coli at 400 MPa, 4 min, and reduction of >6.5 logs in B. subtilis (vegetative cells) starting at 200 MPa, 2 min. For yeast, HHPcarb+CO2 increased the inactivation of HHP from 4.7-log to 6.2-log reduction at 250 MPa, 4 min. The synergistic effect of CO2 with HHP increased with increasing time and pressure. HHPcarb+CO2 treatment did not alter the appearance and color, while affecting the texture and flavor of unsweetened feijoa samples. There were no differences in sensory attributes and preferences between HHPcarb+CO2 and fresh sweetened products. Addition of CO2 in HHP treatment can reduce process pressure and time, and better preserve product quality. A higher microbial inactivation of Escherichia coli, Bacillus subtilis and Saccharomyces cerevisiae by combining dense phase carbon dioxide and high hydrostatic pressure was observed. For sweetened products there were no significant differences in sensory attributes and preferences between samples treated by the combined method and the fresh samples. In conclusion, addition of CO2 in HHP treatment of juices could

  13. Sulfur-oxidizing bacteria dominate the microbial diversity shift during the pyrite and low-grade pyrolusite bioleaching process.

    Science.gov (United States)

    Han, Yifan; Ma, Xiaomei; Zhao, Wei; Chang, Yunkang; Zhang, Xiaoxia; Wang, Xingbiao; Wang, Jingjing; Huang, Zhiyong

    2013-10-01

    The microbial ecology of the pyrite-pyrolusite bioleaching system and its interaction with ore has not been well-described. A 16S rRNA gene clone library was created to evaluate changes in the microbial community at different stages of the pyrite-pyrolusite bioleaching process in a shaken flask. The results revealed that the bacterial community was disturbed after 5 days of the reaction. Phylogenetic analysis of 16S rRNA sequences demonstrated that the predominant microorganisms were members of a genus of sulfur-oxidizing bacteria, Thiomonas sp., that subsequently remained dominant during the bioleaching process. Compared with iron-oxidizing bacteria, sulfur-oxidizing bacteria were more favorable to the pyrite-pyrolusite bioleaching system. Decreased pH due to microbial acid production was an important condition for bioleaching efficiency. Iron-oxidizing bacteria competed for pyrite reduction power with Mn(IV) in pyrolusite under specific conditions. These results extend our knowledge of microbial dynamics during pyrite-pyrolusite bioleaching, which is a key issue to improve commercial applications. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  14. High microbial loads found in minimally-processed sliced mushrooms from Italian market

    Directory of Open Access Journals (Sweden)

    Haiyang Jiang

    2018-04-01

    Full Text Available There is an increased consumer interest in minimally processed vegetables that has led to the development of products, such as pre-cut sliced mushrooms. Few data are available on the hygienic condition and the presence of foodborne pathogens in such products. Therefore, the current study aimed to evaluate the safety and hygienic characteristics of both ready-to-eat and ready-to-cook, pre-cut sliced mushrooms obtained from a local Italian market. For the evaluation of the hygienic condition, the aerobic mesophilic bacteria, aerobic psychrotrophic bacteria and Escherichia coli enumerations were performed. Salmonella spp., Listeria monocytogenes and Campylobacter spp. were considered in the assessment of the foodborne pathogens. High microbial loads were detected, including counts higher than 5 log CFU/g for E. coli and 6 log CFU/g for the other bacteria counts considered, but no pathogens were found. Ready-to-eat and ready-to-cook products differed only for aerobic mesophilic counts (7.87 and 8.26 log CFU/g, respectively, P=0.003. Strategies to enhance the hygienic level of the mushrooms, particularly the ready-to-eat products, are needed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-01-01

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

  16. High microbial loads found in minimally-processed sliced mushrooms from Italian market.

    Science.gov (United States)

    Jiang, Haiyang; Miraglia, Dino; Ranucci, David; Donnini, Domizia; Roila, Rossana; Branciari, Raffaella; Li, Cheng

    2018-03-31

    There is an increased consumer interest in minimally processed vegetables that has led to the development of products, such as pre-cut sliced mushrooms. Few data are available on the hygienic condition and the presence of foodborne pathogens in such products. Therefore, the current study aimed to evaluate the safety and hygienic characteristics of both ready-to-eat and ready-to-cook, pre-cut sliced mushrooms obtained from a local Italian market. For the evaluation of the hygienic condition, the aerobic mesophilic bacteria, aerobic psychrotrophic bacteria and Escherichia coli enumerations were performed. Salmonella spp., Listeria monocytogenes and Campylobacter spp. were considered in the assessment of the foodborne pathogens. High microbial loads were detected, including counts higher than 5 log CFU/g for E. coli and 6 log CFU/g for the other bacteria counts considered, but no pathogens were found. Ready-to-eat and ready-to-cook products differed only for aerobic mesophilic counts (7.87 and 8.26 log CFU/g, respectively, P=0.003). Strategies to enhance the hygienic level of the mushrooms, particularly the ready-to-eat products, are needed.

  17. The microbial community in a high-temperature enhanced biological phosphorus removal (EBPR process

    Directory of Open Access Journals (Sweden)

    Ying Hui Ong

    2016-01-01

    Full Text Available An enhanced biological phosphorus removal (EBPR process operated at a relatively high temperature, 28 °C, removed 85% carbon and 99% phosphorus from wastewater over a period of two years. This study investigated its microbial community through fluorescent in situ hybridization (FISH and clone library generation. Through FISH, considerably more Candidatus “Accumulibacter phosphatis” (Accumulibacter-polyphosphate accumulating organisms (PAOs than Candidatus ‘Competibacter phosphatis’ (Competibacter-glycogen accumulating organisms were detected in the reactor, at 36 and 7% of total bacterial population, respectively. A low ratio of Glycogen/Volatile Fatty Acid of 0.69 further indicated the dominance of PAOs in the reactor. From clone library generated, 26 operational taxonomy units were retrieved from the sludge and a diverse population was shown, comprising Proteobacteria (69.6%, Actinobacteria (13.7%, Bacteroidetes (9.8%, Firmicutes (2.94%, Planctomycetes (1.96%, and Acidobacteria (1.47%. Accumulibacter are the only recognized PAOs revealed by the clone library. Both the clone library and FISH results strongly suggest that Accumulibacter are the major PAOs responsible for the phosphorus removal in this long-term EBPR at relatively high temperature.

  18. Evaluating the Metal Tolerance Capacity of Microbial Communities Isolated from Alberta Oil Sands Process Water.

    Directory of Open Access Journals (Sweden)

    Mathew L Frankel

    Full Text Available Anthropogenic activities have resulted in the intensified use of water resources. For example, open pit bitumen extraction by Canada's oil sands operations uses an estimated volume of three barrels of water for every barrel of oil produced. The waste tailings-oil sands process water (OSPW-are stored in holding ponds, and present an environmental concern as they are comprised of residual hydrocarbons and metals. Following the hypothesis that endogenous OSPW microbial communities have an enhanced tolerance to heavy metals, we tested the capacity of planktonic and biofilm populations from OSPW to withstand metal ion challenges, using Cupriavidus metallidurans, a known metal-resistant organism, for comparison. The toxicity of the metals toward biofilm and planktonic bacterial populations was determined by measuring the minimum biofilm inhibitory concentrations (MBICs and planktonic minimum inhibitory concentrations (MICs using the MBEC ™ assay. We observed that the OSPW community and C. metallidurans had similar tolerances to 22 different metals. While thiophillic elements (Te, Ag, Cd, Ni were found to be most toxic, the OSPW consortia demonstrated higher tolerance to metals reported in tailings ponds (Al, Fe, Mo, Pb. Metal toxicity correlated with a number of physicochemical characteristics of the metals. Parameters reflecting metal-ligand affinities showed fewer and weaker correlations for the community compared to C. metallidurans, suggesting that the OSPW consortia may have developed tolerance mechanisms toward metals present in their environment.

  19. Considering a Threshold Energy in Reactive Transport Modeling of Microbially Mediated Redox Reactions in an Arsenic-Affected Aquifer

    Directory of Open Access Journals (Sweden)

    Marco Rotiroti

    2018-01-01

    Full Text Available The reductive dissolution of Fe-oxide driven by organic matter oxidation is the primary mechanism accepted for As mobilization in several alluvial aquifers. These processes are often mediated by microorganisms that require a minimum Gibbs energy available to conduct the reaction in order to sustain their life functions. Implementing this threshold energy in reactive transport modeling is rarely used in the existing literature. This work presents a 1D reactive transport modeling of As mobilization by the reductive dissolution of Fe-oxide and subsequent immobilization by co-precipitation in iron sulfides considering a threshold energy for the following terminal electron accepting processes: (a Fe-oxide reduction, (b sulfate reduction, and (c methanogenesis. The model is then extended by implementing a threshold energy on both reaction directions for the redox reaction pairs Fe(III reduction/Fe(II oxidation and methanogenesis/methane oxidation. The optimal threshold energy fitted in 4.50, 3.76, and 1.60 kJ/mol e− for sulfate reduction, Fe(III reduction/Fe(II oxidation, and methanogenesis/methane oxidation, respectively. The use of models implementing bidirectional threshold energy is needed when a redox reaction pair can be transported between domains with different redox potentials. This may often occur in 2D or 3D simulations.

  20. Using integrated environmental modeling to automate a process-based Quantitative Microbial Risk Assessment

    Science.gov (United States)

    Integrated Environmental Modeling (IEM) organizes multidisciplinary knowledge that explains and predicts environmental-system response to stressors. A Quantitative Microbial Risk Assessment (QMRA) is an approach integrating a range of disparate data (fate/transport, exposure, an...

  1. Using Integrated Environmental Modeling to Automate a Process-Based Quantitative Microbial Risk Assessment (presentation)

    Science.gov (United States)

    Integrated Environmental Modeling (IEM) organizes multidisciplinary knowledge that explains and predicts environmental-system response to stressors. A Quantitative Microbial Risk Assessment (QMRA) is an approach integrating a range of disparate data (fate/transport, exposure, and...

  2. Atmospheric plasma processes for microbial inactivation: food applications and stress response in Listeria monocytogenes

    OpenAIRE

    Gozzi, Giorgia

    2015-01-01

    This PhD thesis is focused on cold atmospheric plasma treatments (GP) for microbial inactivation in food applications. In fact GP represents a promising emerging technology alternative to the traditional methods for the decontamination of foods. The objectives of this work were to evaluate: - the effects of GP treatments on microbial inactivation in model systems and in real foods; - the stress response in L. monocytogenes following exposure to different GP treatments. As far as t...

  3. A novel theory: biological processes mostly involve two types of mediators, namely general and specific mediators Endogenous small radicals such as superoxide and nitric oxide may play a role of general mediator in biological processes.

    Science.gov (United States)

    Mo, Jian

    2005-01-01

    A great number of papers have shown that free radicals as well as bioactive molecules can play a role of mediator in a wide spectrum of biological processes, but the biological actions and chemical reactivity of the free radicals are quite different from that of the bioactive molecules, and that a wide variety of bioactive molecules can be easily modified by free radicals due to having functional groups sensitive to redox, and the significance of the interaction between the free radicals and the bioactive molecules in biological processes has been confirmed by the results of some in vitro and in vivo studies. Based on these evidence, this article presented a novel theory about the mediators of biological processes. The essentials of the theory are: (a) mediators of biological processes can be classified into general and specific mediators; the general mediators include two types of free radicals, namely superoxide and nitric oxide; the specific mediators include a wide variety of bioactive molecules, such as specific enzymes, transcription factors, cytokines and eicosanoids; (b) a general mediator can modify almost any class of the biomolecules, and thus play a role of mediator in nearly every biological process via diverse mechanisms; a specific mediator always acts selectively on certain classes of the biomolecules, and may play a role of mediator in different biological processes via a same mechanism; (c) biological processes are mostly controlled by networks of their mediators, so the free radicals can regulate the last consequence of a biological process by modifying some types of the bioactive molecules, or in cooperation with these bioactive molecules; the biological actions of superoxide and nitric oxide may be synergistic or antagonistic. According to this theory, keeping the integrity of these networks and the balance between the free radicals and the bioactive molecules as well as the balance between the free radicals and the free radical scavengers

  4. Nanoporous Mo2C functionalized 3D carbon architecture anode for boosting flavins mediated interfacial bioelectrocatalysis in microbial fuel cells

    Science.gov (United States)

    Zou, Long; Lu, Zhisong; Huang, Yunhong; Long, Zhong-er; Qiao, Yan

    2017-08-01

    An efficient microbial electrocatalysis in microbial fuel cells (MFCs) needs both high loading of microbes (biocatalysts) and robust interfacial electron transfer from microbes to electrode. Herein a nanoporous molybdenum carbide (Mo2C) functionalized carbon felt electrode with rich 3D hierarchical porous architecture is applied as MFC anode to achieve superior electrocatalytic performance. The nanoporous Mo2C functionalized anode exhibits strikingly improved microbial electrocatalysis in MFCs with 5-fold higher power density and long-term stability of electricity production. The great enhancement is attributed to the introduction of rough Mo2C nanostructural interface into macroporous carbon architecture for promoting microbial growth with great excretion of endogenous electron shuttles (flavins) and rich available nanopores for enlarging electrochemically active surface area. Importantly, the nanoporous Mo2C functionalized anode is revealed for the first time to have unique electrocatalytic activity towards redox reaction of flavins with more negative redox potential, indicating a more favourable thermodynamic driving force for anodic electron transfer. This work not only provides a promising electrode for high performance MFCs but also brings up a new insight into the effect of nanostructured materials on interfacial bioelectrocatalysis.

  5. Influences of Coupled Hydrologic and Microbial Processes on River Corridor Biogeochemistry and Ecology

    Science.gov (United States)

    Scheibe, T. D.; Song, H. S.; Stegen, J.; Graham, E.; Bao, J.; Goldman, A.; Zhou, T.; Crump, A.; Hou, Z.; Hammond, G. E.; Chen, X.; Huang, M.; Zhang, X.; Nelson, W. C.; Garayburu-Caruso, V. A.

    2017-12-01

    The exchange of water between rivers and surrounding subsurface environments (hydrologic exchange flows or HEFs) is a vital aspect of river ecology and watershed function. HEFs play a key role in water quality, nutrient cycling, and ecosystem health, and they modulate water temperatures and enhance exchange of terrestrial and aquatic nutrients, which lead to elevated biogeochemical activity. However, these coupled hydrologic and microbiological processes are not well understood, particularly in the context of large managed river systems with highly variable discharge, and are poorly represented in system-scale quantitative models. Using the 75 km Hanford Reach of the Columbia River as the research domain, we apply high-resolution flow simulations supported by field observations to understand how variable river discharge interacts with hydromorphic and hydrogeologic structures to generate HEFs and distributions of subsurface residence times. We combine this understanding of hydrologic processes with microbiological activity measurements and reactive transport models to elucidate the holistic impacts of variable discharge on river corridor (surface and subsurface) ecosystems. In particular, our project seeks to develop and test new conceptual and numerical models that explicitly incorporate i) the character (chemical speciation and thermodynamics) of natural organic matter as it varies along flow paths and through mixing of groundwater and surface water, and ii) the history-dependent response of microbial communities to varying time scales of inundation associated with fluctuations in river discharge. The results of these high-resolution mechanistic models are guiding formulation and parameterization of reduced-order models applicable at reach to watershed scales. New understanding of coupled hydrology and microbiology in the river corridor will play a key role in reduction of uncertainties associated with major Earth system biogeochemical fluxes, improving

  6. The effect of microbial activity and adsorption processes on groundwater dissolved organic carbon character and concentration

    Science.gov (United States)

    Meredith, K.; McDonough, L.; Oudone, P.; Rutlidge, H.; O'Carroll, D. M.; Andersen, M. S.; Baker, A.

    2017-12-01

    Balancing the terrestrial global carbon budget has proven to be a significant challenge. Whilst the movement of carbon in the atmosphere, rivers and oceans has been extensively studied, the potential for groundwater to act as a carbon source or sink through both microbial activity and sorption to and from mineral surfaces, is poorly understood. To investigate the biodegradable component of groundwater dissolved organic carbon (DOC), groundwater samples were collected from multiple coastal and inland sites. Water quality parameters such as pH, electrical conductivity, temperature, dissolved oxygen were measured in the field. Samples were analysed and characterised for their biodegradable DOC content using spectrofluorometric and Liquid Chromatography-Organic Carbon Detection (LC-OCD) techniques at set intervals within a 28 day period. Further to this, we performed laboratory sorption experiments on our groundwater samples using different minerals to examine the effect of adsorption processes on DOC character and concentration. Calcium carbonate, quartz and iron coated quartz were heated to 400ºC to remove potential carbon contamination, and then added at various known masses (0 mg to 10 g) to 50 mL of groundwater. Samples were then rotated for two hours, filtered at 0.2 μm and analysed by LC-OCD. This research forms part of an ongoing project which will assist in identifying the factors affecting the mobilisation, transport and removal of DOC in uncontaminated groundwater. By quantifying the relative importance of these processes, we can then determine whether the groundwater is a carbon source or sink. Importantly, this information will help guide policy and identify the need to include groundwater resources as part of the carbon economy.

  7. The process-related dynamics of microbial community during a simulated fermentation of Chinese strong-flavored liquor.

    Science.gov (United States)

    Zhang, Yanyan; Zhu, Xiaoyu; Li, Xiangzhen; Tao, Yong; Jia, Jia; He, Xiaohong

    2017-09-15

    Famous Chinese strong-flavored liquor (CSFL) is brewed by microbial consortia in a special fermentation pit (FT). However, the fermentation process was not fully understood owing to the complicate community structure and metabolism. In this study, the process-related dynamics of microbial communities and main flavor compounds during the 70-day fermentation process were investigated in a simulated fermentation system. A three-phase model was proposed to characterize the process of the CSFL fermentation. (i) In the early fermentation period (1-23 days), glucose was produced from macromolecular carbohydrates (e.g., starch). The prokaryotic diversity decreased significantly. The Lactobacillaceae gradually predominated in the prokaryotic community. In contrast, the eukaryotic diversity rose remarkably in this stage. Thermoascus, Aspergillus, Rhizopus and unidentified Saccharomycetales were dominant eukaryotic members. (ii) In the middle fermentation period (23-48 days), glucose concentration decreased while lactate acid and ethanol increased significantly. Prokaryotic community was almost dominated by the Lactobacillus, while eukaryotic community was mainly comprised of Thermoascus, Emericella and Aspergillus. (iii) In the later fermentation period (48-70 days), the concentrations of ethyl esters, especially ethyl caproate, increased remarkably. The CSFL fermentation could undergo three stages: saccharification, glycolysis and esterification. Saccharomycetales, Monascus, and Rhizopus were positively correlated to glucose concentration (P fermentation, were observed firstly. This study observed comprehensive dynamics of microbial communities during the CSFL fermentation, and it further revealed the correlations between some crucial microorganisms and flavoring chemicals (FCs). The results from this study help to design effective strategies to manipulate microbial consortia for fermentation process optimization in the CSFL brew practice.

  8. Nitrogen cycling processes and microbial community composition in bed sediments in the Yukon River at Pilot Station

    Science.gov (United States)

    Repert, Deborah A.; Underwood, Jennifer C.; Smith, Richard L.; Song, Bongkeun

    2014-01-01

    Information on the contribution of nitrogen (N)-cycling processes in bed sediments to river nutrient fluxes in large northern latitude river systems is limited. This study examined the relationship between N-cycling processes in bed sediments and N speciation and loading in the Yukon River near its mouth at the Bering Sea. We conducted laboratory bioassays to measure N-cycling processes in sediment samples collected over distinct water cycle seasons. In conjunction, the microbial community composition in the bed sediments using genes involved in N-cycling (narG, napA, nosZ, and amoA) and 16S rRNA gene pyrosequences was examined. Temporal variation was observed in net N mineralization, nitrate uptake, and denitrification rate potentials and correlated strongly with sediment carbon (C) and extractable N content and microbial community composition rather than with river water nutrient concentrations. The C content of the bed sediment was notably impacted by the spring flood, ranging from 1.1% in the midst of an ice-jam to 0.1% immediately after ice-out, suggesting a buildup of organic material (OM) prior to scouring of the bed sediments during ice break up. The dominant members of the microbial community that explained differences in N-processing rates belonged to the genera Crenothrix,Flavobacterium, and the family of Comamonadaceae. Our results suggest that biogeochemical processing rates in the bed sediments appear to be more coupled to hydrology, nutrient availability in the sediments, and microbial community composition rather than river nutrient concentrations at Pilot Station.

  9. A network model shows the importance of coupled processes in the microbial N cycle in the Cape Fear River Estuary

    Science.gov (United States)

    Hines, David E.; Lisa, Jessica A.; Song, Bongkeun; Tobias, Craig R.; Borrett, Stuart R.

    2012-06-01

    Estuaries serve important ecological and economic functions including habitat provision and the removal of nutrients. Eutrophication can overwhelm the nutrient removal capacity of estuaries and poses a widely recognized threat to the health and function of these ecosystems. Denitrification and anaerobic ammonium oxidation (anammox) are microbial processes responsible for the removal of fixed nitrogen and diminish the effects of eutrophication. Both of these microbial removal processes can be influenced by direct inputs of dissolved inorganic nitrogen substrates or supported by microbial interactions with other nitrogen transforming pathways such as nitrification and dissimilatory nitrate reduction to ammonium (DNRA). The coupling of nitrogen removal pathways to other transformation pathways facilitates the removal of some forms of inorganic nitrogen; however, differentiating between direct and coupled nitrogen removal is difficult. Network modeling provides a tool to examine interactions among microbial nitrogen cycling processes and to determine the within-system history of nitrogen involved in denitrification and anammox. To examine the coupling of nitrogen cycling processes, we built a nitrogen budget mass balance network model in two adjacent 1 cm3 sections of bottom water and sediment in the oligohaline portion of the Cape Fear River Estuary, NC, USA. Pathway, flow, and environ ecological network analyses were conducted to characterize the organization of nitrogen flow in the estuary and to estimate the coupling of nitrification to denitrification and of nitrification and DNRA to anammox. Centrality analysis indicated NH4+ is the most important form of nitrogen involved in removal processes. The model analysis further suggested that direct denitrification and coupled nitrification-denitrification had similar contributions to nitrogen removal while direct anammox was dominant to coupled forms of anammox. Finally, results also indicated that partial

  10. Alterations in soil microbial activity and N-transformation processes due to sulfadiazine loads in pig-manure

    International Nuclear Information System (INIS)

    Kotzerke, Anja; Sharma, Shilpi; Schauss, Kristina; Heuer, Holger; Thiele-Bruhn, Soeren; Smalla, Kornelia; Wilke, Berndt-Michael; Schloter, Michael

    2008-01-01

    Most veterinary drugs enter the environment via manure application. However, it is unclear how these substances interact with soil biota. Therefore, it was the aim of the present study to investigate the effects of manure containing different concentrations of the antibiotic sulfadiazine (SDZ) on the soil microbial communities. It was shown that manure alone has a stimulating effect on microbial activity. Only potential nitrification was negatively influenced by manure application. The addition of SDZ to the manure reduced microbial activity. Depending on the SDZ concentration, levels of activity were in the range of the control soil without manure application. Also, selected processes in nitrogen turnover were negatively influenced by the addition of SDZ to the manure, with nitrification being the only exception. The effects were visible for up to 4 days after application of the manure with or without SDZ and were correlated with the bioavailability of the antibiotic. - This study gives first insights into the effects of manure containing the antibiotic sulfadiazine on microbial activity and nitrogen transformation potentials in soil

  11. Effect of combination processing on the microbial, chemical and sensory quality of ready-to-eat (RTE) vegetable pulav

    International Nuclear Information System (INIS)

    Kumar, R.; George, Johnsy; Rajamanickam, R.; Nataraju, S.; Sabhapathy, S.N.; Bawa, A.S.

    2011-01-01

    Effect of irradiation in combination with retort processing on the shelf life and safety aspects of an ethnic Indian food product like vegetable pulav was investigated. Gamma irradiation of RTE vegetable pulav was carried out at different dosage rates with 60 Co followed by retort processing. The combination processed samples were analysed for microbiological, chemical and sensory characteristics. Microbiological analysis indicated that irradiation in combination with retort processing has significantly reduced the microbial loads whereas the chemical and sensory analysis proved that this combination processing is effective in retaining the properties even after storage for one year at ambient conditions. The results also indicated that a minimum irradiation dosage at 4.0 kGy along with retort processing at an F 0 value of 2.0 is needed to achieve the desired shelf life with improved organoleptic qualities. - Highlights: → A combination processing involving gamma irradiation and retort processing. → Combination processing reduced microbial loads. → Minimum dose of 4.0 kGy together with retort processing at F 0 -2.0 is required to achieve commercial sterility.

  12. Effect of combination processing on the microbial, chemical and sensory quality of ready-to-eat (RTE) vegetable pulav

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R., E-mail: kumardfrl@gmail.com [Defence Food Research Laboratory, Mysore, Karnataka 570011 (India); George, Johnsy; Rajamanickam, R.; Nataraju, S.; Sabhapathy, S.N.; Bawa, A.S. [Defence Food Research Laboratory, Mysore, Karnataka 570011 (India)

    2011-12-15

    Effect of irradiation in combination with retort processing on the shelf life and safety aspects of an ethnic Indian food product like vegetable pulav was investigated. Gamma irradiation of RTE vegetable pulav was carried out at different dosage rates with {sup 60}Co followed by retort processing. The combination processed samples were analysed for microbiological, chemical and sensory characteristics. Microbiological analysis indicated that irradiation in combination with retort processing has significantly reduced the microbial loads whereas the chemical and sensory analysis proved that this combination processing is effective in retaining the properties even after storage for one year at ambient conditions. The results also indicated that a minimum irradiation dosage at 4.0 kGy along with retort processing at an F{sub 0} value of 2.0 is needed to achieve the desired shelf life with improved organoleptic qualities. - Highlights: > A combination processing involving gamma irradiation and retort processing. > Combination processing reduced microbial loads. > Minimum dose of 4.0 kGy together with retort processing at F{sub 0}-2.0 is required to achieve commercial sterility.

  13. Peatland Microbial Communities and Decomposition Processes in the James Bay Lowlands, Canada

    Science.gov (United States)

    Preston, Michael D.; Smemo, Kurt A.; McLaughlin, James W.; Basiliko, Nathan

    2012-01-01

    Northern peatlands are a large repository of atmospheric carbon due to an imbalance between primary production by plants and microbial decomposition. The James Bay Lowlands (JBL) of northern Ontario are a large peatland-complex but remain relatively unstudied. Climate change models predict the region will experience warmer and drier conditions, potentially altering plant community composition, and shifting the region from a long-term carbon sink to a source. We collected a peat core from two geographically separated (ca. 200 km) ombrotrophic peatlands (Victor and Kinoje Bogs) and one minerotrophic peatland (Victor Fen) located near Victor Bog within the JBL. We characterized (i) archaeal, bacterial, and fungal community structure with terminal restriction fragment length polymorphism of ribosomal DNA, (ii) estimated microbial activity using community level physiological profiling and extracellular enzymes activities, and (iii) the aeration and temperature dependence of carbon mineralization at three depths (0–10, 50–60, and 100–110 cm) from each site. Similar dominant microbial taxa were observed at all three peatlands despite differences in nutrient content and substrate quality. In contrast, we observed differences in basal respiration, enzyme activity, and the magnitude of substrate utilization, which were all generally higher at Victor Fen and similar between the two bogs. However, there was no preferential mineralization of carbon substrates between the bogs and fens. Microbial community composition did not correlate with measures of microbial activity but pH was a strong predictor of activity across all sites and depths. Increased peat temperature and aeration stimulated CO2 production but this did not correlate with a change in enzyme activities. Potential microbial activity in the JBL appears to be influenced by the quality of the peat substrate and the presence of microbial inhibitors, which suggests the existing peat substrate will have a large

  14. Mediation and Due Process Procedures in Special Education: An Analysis of State Policies. Final Report. Project FORUM.

    Science.gov (United States)

    Ahearn, Eileen M.

    This survey of 50 states and 3 of 10 non-state U.S. jurisdictions concerning state due process procedures focuses mainly on the use of mediation as a form of dispute resolution that offers an alternative to due process hearings in special education. A background section discusses the definition of mediation and the mediation process. Survey…

  15. Strategy choice mediates the link between auditory processing and spelling.

    Science.gov (United States)

    Kwong, Tru E; Brachman, Kyle J

    2014-01-01

    Relations among linguistic auditory processing, nonlinguistic auditory processing, spelling ability, and spelling strategy choice were examined. Sixty-three undergraduate students completed measures of auditory processing (one involving distinguishing similar tones, one involving distinguishing similar phonemes, and one involving selecting appropriate spellings for individual phonemes). Participants also completed a modified version of a standardized spelling test, and a secondary spelling test with retrospective strategy reports. Once testing was completed, participants were divided into phonological versus nonphonological spellers on the basis of the number of words they spelled using phonological strategies only. Results indicated a) moderate to strong positive correlations among the different auditory processing tasks in terms of reaction time, but not accuracy levels, and b) weak to moderate positive correlations between measures of linguistic auditory processing (phoneme distinction and phoneme spelling choice in the presence of foils) and spelling ability for phonological spellers, but not for nonphonological spellers. These results suggest a possible explanation for past contradictory research on auditory processing and spelling, which has been divided in terms of whether or not disabled spellers seemed to have poorer auditory processing than did typically developing spellers, and suggest implications for teaching spelling to children with good versus poor auditory processing abilities.

  16. Testing the Causal Mediation Component of Dodge's Social Information Processing Model of Social Competence and Depression

    Science.gov (United States)

    Possel, Patrick; Seemann, Simone; Ahrens, Stefanie; Hautzinger, Martin

    2006-01-01

    In Dodge's model of "social information processing" depression is the result of a linear sequence of five stages of information processing ("Annu Rev Psychol" 44: 559-584, 1993). These stages follow a person's reaction to situational stimuli, such that each stage of information processing mediates the relationship between earlier and later stages.…

  17. Mixed waste treatment with a mediated electrochemical process

    International Nuclear Information System (INIS)

    Hickman, R.G.; Gray, L.W.; Chiba, Z.

    1991-01-01

    The process described in this paper is intended to convert mixed waste containing toxic organic compounds (not heavy metals) to ordinary radioactive waste, which is treatable. The process achieves its goal by oxidizing hydrocarbons to CO 2 and H 2 O. Other atoms that may be present in the toxic organic generally are converted to nonhazardous anions such as sulfate and phosphate. This electro chemical conversion is performed at conditions of temperature and pressure that are just moderately above ambient conditions. Gaseous hydroxides and oxyhydroxides that are formed by many radionuclides during incineration cannot form in this process. 1 ref., 3 figs

  18. Assessment of microbial processes on radionuclide mobility in shallow land burial

    International Nuclear Information System (INIS)

    Colombo, P.; Tate, R.L. III; Weiss, A.J.

    1982-07-01

    The impact of microbial metabolism of the organic substituents of low level radioactive wastes on radionuclide mobility in disposal sites, the nature of the microbial transformations involved in this metabolism and the effect of the prevailing environmental parameters on the quantities and types of metabolic intermediates accumulated were examined. Since both aerobic and anaerobic periods can occur during trench ecosystem development, oxidation capacities of the microbial community in the presence and absence of oxygen were analyzed. Results of gas studies performed at three commercial low level radioactive waste disposal sites were reviewed. Several deficiencies in available data were determined. Further research needs are suggested. This assessment has demonstrated that the biochemical capabilities expressed within the low level radioactive waste disposal site are common to a wide variety of soil bacteria. Hence, assuming trenches would not be placed in sites with such extreme abiotic conditions that all microbial activity is precluded, the microbial populations needed for colonization and decomposition of the organic waste substances are readily provided from the waste itself and from the soil of existing and any proposed disposal sites. Indeed, considering the ubiquity of occurrence of the microorganisms responsible for waste decomposition and the chemical nature of the organic waste material, long-term prevention of biodecomposition is difficult, if not impossible

  19. Effect of different film packaging on microbial growth in minimally processed cactus pear (Opuntia ficus-indica).

    Science.gov (United States)

    Palma, A; Mangia, N P; Fadda, A; Barberis, A; Schirra, M; D'Aquino, S

    2013-01-01

    Microorganisms are natural contaminants of fresh produce and minimally processed products, and contamination arises from a number of sources, including the environment, postharvest handling and processing. Fresh-cut products are particularly susceptible to microbial contaminations because of the changes occurring in the tissues during processing. In package gas composition of modified atmosphere packaging (MAP) in combination with low storage temperatures besides reducing physiological activity of packaged produce, can also delay pathogen growth. Present study investigated on the effect of MAPs, achieved with different plastic films, on microbial growth of minimally processed cactus pear (Opuntio ficus-indica) fruit. Five different plastic materials were used for packaging the manually peeled fruit. That is: a) polypropylene film (Termoplast MY 40 micron thickness, O2 transmission rate 300 cc/m2/24h); b) polyethylene film (Bolphane BHE, 11 micron thickness, O2 transmission rate 19000 cc/m2/24h); c) polypropylene laser-perforated films (Mach Packaging) with 8, 16 or 32 100-micron holes. Total aerobic psychrophilic, mesophilic microorganisms, Enterobacteriaceae, yeast, mould populations and in-package CO2, O2 and C2H4 were determined at each storage time. Different final gas compositions, ranging from 7.8 KPa to 17.1 KPa O2, and 12.7 KPa to 2.6 KPa CO2, were achieved with MY and micro perforated films, respectively. Differences were detected in the mesophilic, Enterobacteriaceae and yeast loads, while no difference was detected in psychrophilic microorganisms. At the end of storage, microbial load in fruits sealed with MY film was significantly lower than in those sealed with BHE and micro perforated films. Furthermore, fruits packed with micro-perforated films showed the highest microbial load. This occurrence may in part be related to in-package gas composition and in part to a continuous contamination of microorganisms through micro-holes.

  20. [Decomposition of corpses--a microbial degradation process with special reference to mummification, formation of adipocere and incomplete putrified corpes].

    Science.gov (United States)

    Schoenen, Dirk

    2013-01-01

    Decomposition of the human body is a microbial process. It is influenced by the environmental situation and it depends to a high degree on the exchange of substances between the corpse and the environment. Mummification occurs at low humidity or frost. Adipocere arises from lack of oxygen, incomplete putrified corpses develop when there is no exchange of air or water between the corpse and the environment.

  1. Assessment of Peer Mediation Process from Conflicting Students’ Point of Views

    Directory of Open Access Journals (Sweden)

    Fulya TÜRK

    2016-12-01

    Full Text Available The purpose of this study was to analyze peer mediation process that was applied in a high school on conflicting students’ point of views. This research was carried out in a high school in Denizli. After ten sessions of training in peer mediation, peer mediators mediated peers’ real conflicts. In the research, 41 students (28 girls, 13 boys who got help at least once were interviewed as a party to the conflict. Through semistructured interviews with conflicting students, the mediation process has been evaluated through the point of views of students. Eight questions were asked about the conflicting parties. Verbal data obtained from interviews were analyzed using the content analysis. When conflicting students’ opinions and experiences about peer mediation were analyzed, it is seen that they were satisfied regarding the process, they have resolved their conflicts in a constructive and peaceful way, their friendship has been continuing as before. All of these results also indicate that peer mediation is an effective method of resolving student conflicts constructively

  2. Monitoring of the microbial communities involved in the soy sauce manufacturing process by PCR-denaturing gradient gel electrophoresis.

    Science.gov (United States)

    Tanaka, Yasushi; Watanabe, Jun; Mogi, Yoshinobu

    2012-08-01

    Soy sauce is a traditional seasoning produced through the fermentation of soybeans and wheat using microbes. In this study, the microbial communities involved in the soy sauce manufacturing process were analyzed by PCR-Denaturing Gradient Gel Electrophoresis (PCR-DGGE). The bacterial DGGE profile indicated that the bacterial microbes in the koji were Weissella cibaria (Weissella confusa, Weissella kimchii, Weissella salipiscis, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus iners, or Streptococcus thermophilus), Staphylococcus gallinarum (or Staphylococcus xylosus), and Staphylococcus kloosii. In addition to these bacteria, Tetragenococcus halophilus was also detected in the mash during lactic acid fermentation. The fungal DGGE profile indicated that the fungal microbes in the koji were not only Aspergillus oryzae but also several yeasts. In the mash, Zygosaccharomyces rouxii appeared in the early fermentation stage, Candida etchellsii (or Candida nodaensis) and Candida versatilis were detected at the middle fermentation stage, and Candida etchellsii was detected at the mature fermentation stage. These results suggest that the microbial communities present during the soy sauce manufacturing process change drastically throughout its production. This is the first report to reveal the microbial communities involved in the soy sauce manufacturing process using a culture-independent method. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  3. Organic matter processing by microbial communities throughout the Atlantic water column as revealed by metaproteomics

    DEFF Research Database (Denmark)

    Bergauer, Kristin; Fernandez-Guerra, Antonio; Garcia, Juan A L

    2018-01-01

    The phylogenetic composition of the heterotrophic microbial community is depth stratified in the oceanic water column down to abyssopelagic layers. In the layers below the euphotic zone, it has been suggested that heterotrophic microbes rely largely on solubilized particulate organic matter...... as a carbon and energy source rather than on dissolved organic matter. To decipher whether changes in the phylogenetic composition with depth are reflected in changes in the bacterial and archaeal transporter proteins, we generated an extensive metaproteomic and metagenomic dataset of microbial communities...... collected from 100- to 5,000-m depth in the Atlantic Ocean. By identifying which compounds of the organic matter pool are absorbed, transported, and incorporated into microbial cells, intriguing insights into organic matter transformation in the deep ocean emerged. On average, solute transporters accounted...

  4. Hemp fibres: Enzymatic effect of microbial processing on fibre bundle structure

    DEFF Research Database (Denmark)

    Thygesen, Anders; Liu, Ming; Meyer, Anne S.

    2013-01-01

    The effects of microbial pretreatment on hemp fibres were evaluated after microbial retting using the white rot fungi Ceriporiopsis subvermispora and Phlebia radiata Cel 26 and water retting. Based on chemical composition, P. radiata Cel 26 showed the highest selectivity for pectin and lignin...... degradation and lowest cellulose loss (14%) resulting in the highest cellulose content (78.4%) for the treated hemp fibres. The pectin and lignin removal after treatment with P. radiata Cel 26 were of the order 82% and 50%, respectively. Aligned epoxy-matrix composites were made from hemp fibres defibrated...... with the microbial retting to evaluate the effects on their ultrastructure. SEM microscopy of the composites showed low porosity on the fibre surfaces after defibration with P. radiata Cel 26 and C. subvermispora indicating good epoxy polymer impregnation. In contrast, fibres treated by water retting and the raw...

  5. Relating Anaerobic Digestion Microbial Community and Process Function : Supplementary Issue: Water Microbiology

    Directory of Open Access Journals (Sweden)

    Kaushik Venkiteshwaran

    2015-01-01

    Full Text Available Anaerobic digestion (AD involves a consortium of microorganisms that convert substrates into biogas containing methane for renewable energy. The technology has suffered from the perception of being periodically unstable due to limited understanding of the relationship between microbial community structure and function. The emphasis of this review is to describe microbial communities in digesters and quantitative and qualitative relationships between community structure and digester function. Progress has been made in the past few decades to identify key microorganisms influencing AD. Yet, more work is required to realize robust, quantitative relationships between microbial community structure and functions such as methane production rate and resilience after perturbations. Other promising areas of research for improved AD may include methods to increase/control (1 hydrolysis rate, (2 direct interspecies electron transfer to methanogens, (3 community structure–function relationships of methanogens, (4 methanogenesis via acetate oxidation, and (5 bioaugmentation to study community–activity relationships or improve engineered bioprocesses.

  6. MEDIATIC NARRATIVES AND IDENTIFICATION PROCESSES. A THEORETICAL AND METHODOLOGICAL APPROACH

    Directory of Open Access Journals (Sweden)

    Salomé Sola Morales

    2013-04-01

    Full Text Available This article, theoretical and argumentative, lays the conceptual and methodological basis for the study of the link between identity and narrative media identification processes undertaken by individuals and groups. Thus, the setting national identifications, professional, religious or gender is here proposed as the result of the dialectic between the 'media narrative identity', which the media produce and convey, and identification processes that individuals and groups perform. Furthermore we propose the use of the biographical method as a form of empirical approach to psycho-social phenomenon

  7. Development of a Chlorine Dosing Strategy for Fresh Produce Washing Process to Maintain Microbial Food Safety and Minimize Residual Chlorine.

    Science.gov (United States)

    Chen, Xi; Hung, Yen-Con

    2018-05-22

    The residual free chlorine level in fresh produce wash solution is closely correlated to the chemical and microbial safety of produce. Excess amount of free chlorine can quickly react with organic matters to form hazardous disinfection by-products (DBPs) above EPA-permitted levels, whereas deficiency of residual chlorine in produce wash solution may result in incompletely removing pathogens on produce. The purpose of this study was to develop a chlorine dosing strategy to optimize the chlorine dosage during produce washing process without impacting the microbial safety of fresh produce. Prediction equations were developed to estimate free chlorine needed to reach targeted residual chlorine at various sanitizer pH and organic loads, and then validated using fresh-cut iceberg lettuce and whole strawberries in an automated produce washer. Validation results showed that equations successfully predicted the initial chlorine concentration needed to achieve residual chlorine at 10, 30, 60, and 90 mg/L for both lettuce and strawberry washing processes, with the root mean squared error at 4.45 mg/L. The Escherichia coli O157:H7 reductions only slightly increased on iceberg lettuce and strawberries with residual chlorine increasing from 10 to 90 mg/L, indicating that lowering residual chlorine to 10 mg/L would not compromise the antimicrobial efficacy of chlorine-based sanitizer. Based on the prediction equations and E. coli O157:H7 reduction results, a chlorine dosing strategy was developed to help the produce industry to maintain microbial inactivation efficacy without adding excess amount of free chlorine. The chlorine dosing strategy can be used for fresh produce washing process to enhance the microbial food safety and minimize the DBPs formation potential. © 2018 Institute of Food Technologists®.

  8. Integrated systems for biopolymers and bioenergy production from organic waste and by-products: a review of microbial processes.

    Science.gov (United States)

    Pagliano, Giorgia; Ventorino, Valeria; Panico, Antonio; Pepe, Olimpia

    2017-01-01

    Recently, issues concerning the sustainable and harmless disposal of organic solid waste have generated interest in microbial biotechnologies aimed at converting waste materials into bioenergy and biomaterials, thus contributing to a reduction in economic dependence on fossil fuels. To valorize biomass, waste materials derived from agriculture, food processing factories, and municipal organic waste can be used to produce biopolymers, such as biohydrogen and biogas, through different microbial processes. In fact, different bacterial strains can synthesize biopolymers to convert waste materials into valuable intracellular (e.g., polyhydroxyalkanoates) and extracellular (e.g., exopolysaccharides) bioproducts, which are useful for biochemical production. In particular, large numbers of bacteria, including Alcaligenes eutrophus , Alcaligenes latus , Azotobacter vinelandii , Azotobacter chroococcum , Azotobacter beijerincki , methylotrophs, Pseudomonas spp., Bacillus spp., Rhizobium spp., Nocardia spp., and recombinant Escherichia coli , have been successfully used to produce polyhydroxyalkanoates on an industrial scale from different types of organic by-products. Therefore, the development of high-performance microbial strains and the use of by-products and waste as substrates could reasonably make the production costs of biodegradable polymers comparable to those required by petrochemical-derived plastics and promote their use. Many studies have reported use of the same organic substrates as alternative energy sources to produce biogas and biohydrogen through anaerobic digestion as well as dark and photofermentation processes under anaerobic conditions. Therefore, concurrently obtaining bioenergy and biopolymers at a reasonable cost through an integrated system is becoming feasible using by-products and waste as organic carbon sources. An overview of the suitable substrates and microbial strains used in low-cost polyhydroxyalkanoates for biohydrogen and biogas

  9. Effects of grain source, grain processing, and protein degradability on rumen kinetics and microbial protein synthesis in Boer kids.

    Science.gov (United States)

    Brassard, M-E; Chouinard, P Y; Berthiaume, R; Tremblay, G F; Gervais, R; Martineau, R; Cinq-Mars, D

    2015-11-01

    Microbial protein synthesis in the rumen would be optimized when dietary carbohydrates and proteins have synchronized rates and extent of degradation. The aim of this study was to evaluate the effect of varying ruminal degradation rate of energy and nitrogen sources on intake, nitrogen balance, microbial protein yield, and kinetics of nutrients in the rumen of growing kids. Eight Boer goats (38.2 ± 3.0 kg) were used. The treatments were arranged in a split-plot Latin square design with grain sources (barley or corn) forming the main plots (squares). Grain processing methods and levels of protein degradability formed the subplots in a 2 × 2 factorial arrangement for a total of 8 dietary treatments. The grain processing method was rolling for barley and cracking for corn. Levels of protein degradability were obtained by feeding untreated soybean meal (SBM) or heat-treated soybean meal (HSBM). Each experimental period lasted 21 d, consisting of a 10-d adaptation period, a 7-d digestibility determination period, and a 4-d rumen evacuation and sampling period. Kids fed with corn had higher purine derivatives (PD) excretion when coupled with SBM compared with HSBM and the opposite occurred with barley-fed kids ( ≤ 0.01). Unprocessed grain offered with SBM led to higher PD excretion than with HSBM whereas protein degradability had no effect when processed grain was fed ( ≤ 0.03). Results of the current experiment with high-concentrate diets showed that microbial N synthesis could be maximized in goat kids by combining slowly fermented grains (corn or unprocessed grains) with a highly degradable protein supplement (SBM). With barley, a more rapidly fermented grain, a greater microbial N synthesis was observed when supplementing a low-degradable protein (HSBM).

  10. Aromatic-Mediated Carbohydrate Recognition in Processive Serratia marcescens Chitinases.

    Science.gov (United States)

    Jana, Suvamay; Hamre, Anne Grethe; Wildberger, Patricia; Holen, Matilde Mengkrog; Eijsink, Vincent G H; Beckham, Gregg T; Sørlie, Morten; Payne, Christina M

    2016-02-25

    Microorganisms use a host of enzymes, including processive glycoside hydrolases, to deconstruct recalcitrant polysaccharides to sugars. Processive glycoside hydrolases closely associate with polymer chains and repeatedly cleave glycosidic linkages without dissociating from the crystalline surface after each hydrolytic step; they are typically the most abundant enzymes in both natural secretomes and industrial cocktails by virtue of their significant hydrolytic potential. The ubiquity of aromatic residues lining the enzyme catalytic tunnels and clefts is a notable feature of processive glycoside hydrolases. We hypothesized that these aromatic residues have uniquely defined roles, such as substrate chain acquisition and binding in the catalytic tunnel, that are defined by their local environment and position relative to the substrate and the catalytic center. Here, we investigated this hypothesis with variants of Serratia marcescens family 18 processive chitinases ChiA and ChiB. We applied molecular simulation and free energy calculations to assess active site dynamics and ligand binding free energies. Isothermal titration calorimetry provided further insight into enthalpic and entropic contributions to ligand binding free energy. Thus, the roles of six aromatic residues, Trp-167, Trp-275, and Phe-396 in ChiA, and Trp-97, Trp-220, and Phe-190 in ChiB, have been examined. We observed that point mutation of the tryptophan residues to alanine results in unfavorable changes in the free energy of binding relative to wild-type. The most drastic effects were observed for residues positioned at the "entrances" of the deep substrate-binding clefts and known to be important for processivity. Interestingly, phenylalanine mutations in ChiA and ChiB had little to no effect on chito-oligomer binding, in accordance with the limited effects of their removal on chitinase functionality.

  11. Microbial impact on metallic corrosion processes: case of iron reducing bacteria

    International Nuclear Information System (INIS)

    Esnault, Loic; Jullien, Michel; Libert, Marie; Mustin, Christian

    2010-01-01

    corrosion product alteration, magnetite and hematite mainly (c). For that, an optimised method of H2 measure at weak pressure has been realised by gaseous phase chromatography coupled with a sensitive pressure captor. - H 2 + Fe 3+ magnetite → Fe 2+ solution + 2H + (c) The interest of this study is to determine and to understand the reactivity of one model microbe species, the ferric-reducing bacterium 'Schewanella oneidensis strain MR-1', on a Fe(0) corrosion and these corrosion products (magnetite, hematite mainly) in presence or not of clay minerals (bentonite MX80). The introduction of short-term experiments in the scattered environment (batch) over reactivity Iron-bacteria with or without clay mineral is here studied through a kinetic study of H 2 bio-consumed or product, chemical analysis in solution, and by use a crystallo-chemistry tool (XRD and SEM). The main results are bio-alteration of corrosion products with development of ferri-reducing bacterial community. This microbial alteration entails an increase of aqueous corrosion by consumption of corrosion products (passivation layer). In such condition, corrosion process could be reactivated. (authors)

  12. Insight into the prevalence and distribution of microbial contamination to evaluate water management in the fresh produce processing industry.

    Science.gov (United States)

    Holvoet, Kevin; Jacxsens, Liesbeth; Sampers, Imca; Uyttendaele, Mieke

    2012-04-01

    This study provided insight into the degree of microbial contamination in the processing chain of prepacked (bagged) lettuce in two Belgian fresh-cut produce processing companies. The pathogens Salmonella and Listeria monocytogenes were not detected. Total psychrotrophic aerobic bacterial counts (TPACs) in water samples, fresh produce, and environmental samples suggested that the TPAC is not a good indicator of overall quality and best manufacturing practices during production and processing. Because of the high TPACs in the harvested lettuce crops, the process water becomes quickly contaminated, and subsequent TPACs do not change much throughout the production process of a batch. The hygiene indicator Escherichia coli was used to assess the water management practices in these two companies in relation to food safety. Practices such as insufficient cleaning and disinfection of washing baths, irregular refilling of the produce wash baths with water of good microbial quality, and the use of high product/water ratios resulted in a rapid increase in E. coli in the processing water, with potential transfer to the end product (fresh-cut lettuce). The washing step in the production of fresh-cut lettuce was identified as a potential pathway for dispersion of microorganisms and introduction of E. coli to the end product via cross-contamination. An intervention step to reduce microbial contamination is needed, particularly when no sanitizers are used as is the case in some European Union countries. Thus, from a food safety point of view proper water management (and its validation) is a critical point in the fresh-cut produce processing industry.

  13. Rheological and mechanical properties of polyamide 6 modified by electron-beam initiated mediation process

    International Nuclear Information System (INIS)

    Shin, Boo Young; Kim, Jae Hong

    2015-01-01

    Polyamide (PA6) has been modified by electron-beam initiated mediator process to improve drawbacks of PA6. Glycidyl methacrylate (GMA) was chosen as a reactive mediator for modification process of PA6. The mixture of the PA6 and GMA was prepared by using a twin-screw extruder, and then the mixture was exposed to electron-beam irradiation at various doses at room temperature. The modified PA6 were characterized by observing rheological and mechanical properties and compared virgin PA6. Thermal properties, water absorption, and gel fraction were also investigated. Tight gel was not found even when PA6 was irradiated at 200 kGy. Complex viscosity and storage modulus of PA6 were remarkably increased by electron-beam irradiation with medium of GMA. Maximum increase in complex viscosity was 75 times higher than virgin PA6 at 0.1 rad/s when it was irradiated at 200 kGy with the GMA. Mechanical properties were also improved without scarifying of processability. The reaction mechanisms for the mediation process with the reactive mediator of GMA were estimated to elucidate the cause of significantly enhanced rheological and mechanical properties without loss of thermoplasticity. - Highlights: • PA6 was modified by the electron-beam initiated mediation process. • Maximum increase in complex viscosity of modified PA6 was 75 times higher than virgin PA6 at 0.1 rad/s. • Mechanical properties were improved without scarifying of processability. • The GMA as a mediator played a key role in the electron-beam initiated mediation process

  14. Short-sludge age EBPR processMicrobial and biochemical process characterisation during reactor start-up and operation

    DEFF Research Database (Denmark)

    Valverde Pérez, Borja; Wágner, Dorottya Sarolta; Lóránt, Bálint

    2016-01-01

    . In this paper, we report the start-up and operation of a short-SRT enhanced biological phosphorus removal (EBPR) system operated as a sequencing batch reactor (SBR) fed with preclarified municipal wastewater, which is supplemented with propionate. The microbial community was analysed via 16S rRNA amplicon...

  15. Inferring Group Processes from Computer-Mediated Affective Text Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Schryver, Jack C [ORNL; Begoli, Edmon [ORNL; Jose, Ajith [Missouri University of Science and Technology; Griffin, Christopher [Pennsylvania State University

    2011-02-01

    Political communications in the form of unstructured text convey rich connotative meaning that can reveal underlying group social processes. Previous research has focused on sentiment analysis at the document level, but we extend this analysis to sub-document levels through a detailed analysis of affective relationships between entities extracted from a document. Instead of pure sentiment analysis, which is just positive or negative, we explore nuances of affective meaning in 22 affect categories. Our affect propagation algorithm automatically calculates and displays extracted affective relationships among entities in graphical form in our prototype (TEAMSTER), starting with seed lists of affect terms. Several useful metrics are defined to infer underlying group processes by aggregating affective relationships discovered in a text. Our approach has been validated with annotated documents from the MPQA corpus, achieving a performance gain of 74% over comparable random guessers.

  16. Changes in optical characteristics of surface microlayers hint to photochemically and microbially-mediated DOM turnover in the upwelling region off Peru

    Science.gov (United States)

    Galgani, L.; Engel, A.

    2015-12-01

    The coastal upwelling system off Peru is characterized by high biological activity and a pronounced subsurface oxygen minimum zone, as well as associated emissions of atmospheric trace gases such as N2O, CH4 and CO2. During the Meteor (M91) cruise to the Peruvian upwelling system in 2012, we investigated the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like Chromophoric Dissolved Organic Matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. In order to understand organic matter cycling in surface films, we analyzed SML and underlying water samples at 38 stations determining DOC concentration, amino acid composition, marine gels, CDOM and bacterial and phytoplankton abundance as indicators of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slope (S) values and Excitation-Emission Matrix fluorescence (EEMs), which allow to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources and sinks. We identified five fluorescent components of the CDOM pool, of which two had excitation/emission characteristics of protein-like fluorophores and were highly enriched in the SML. CDOM composition and changes in spectral slope properties suggested a local microbial release of HMW DOM directly in the SML as a response to light exposure in this extreme environment. Our results suggest that microbial and photochemical processes play an important role for the production, alteration and loss of optically active substances in the SML.

  17. Recent advances and strategies in process and strain engineering for the production of butyric acid by microbial fermentation.

    Science.gov (United States)

    Luo, Hongzhen; Yang, Rongling; Zhao, Yuping; Wang, Zhaoyu; Liu, Zheng; Huang, Mengyu; Zeng, Qingwei

    2018-04-01

    Butyric acid is an important platform chemical, which is widely used in the fields of food, pharmaceutical, energy, etc. Microbial fermentation as an alternative approach for butyric acid production is attracting great attention as it is an environmentally friendly bioprocessing. However, traditional fermentative butyric acid production is still not economically competitive compared to chemical synthesis route, due to the low titer, low productivity, and high production cost. Therefore, reduction of butyric acid production cost by utilization of alternative inexpensive feedstock, and improvement of butyric acid production and productivity has become an important target. Recently, several advanced strategies have been developed for enhanced butyric acid production, including bioprocess techniques and metabolic engineering methods. This review provides an overview of advances and strategies in process and strain engineering for butyric acid production by microbial fermentation. Additionally, future perspectives on improvement of butyric acid production are also proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Phytase Production and Development of an Ideal Dephytinization Process for Amelioration of Food Nutrition Using Microbial Phytases.

    Science.gov (United States)

    Jain, Jinender; Singh, Bijender

    2017-04-01

    Development of an ideal process for reduction of food phytates using microbial phytases is a demanding task by all food and feed industries all over the world. Phytase production by Bacillus subtilis subsp. subtilis JJBS250 isolated from soil sample was optimized in submerged fermentation using statistical tools. Among all the culture variables tested, sucrose, sodium phytate and Tween-80 were identified as the most significant variables using the Placket-Burman design. Further optimization of these variables resulted in a 6.79-fold improvement in phytase production (7170 U/L) as compared to unoptimized medium. Supplementation of microbial phytases (fungal and bacterial) resulted in improved bioavailability of nutritional components with the concomitant liberation of inorganic phosphorus, reducing sugar, soluble protein and amino acids, thus mitigating anti-nutritional properties of phytic acid.

  19. Effect of high hydrostatic pressure processing on the background microbial loads and quality of cantaloupe puree

    Science.gov (United States)

    The objective of this study was to investigate and evaluate the effects of high hydrostatic pressure (HHP) applied to cantaloupe puree (CP) on microbial loads and product quality during storage for 10 days at 4 degrees C. Freshly prepared, double sealed and double bagged CP (ca. 5 g) was pressure tr...

  20. Integrated microbial processes for biofuels and high value-added products: the way to improve the cost effectiveness of biofuel production.

    Science.gov (United States)

    da Silva, Teresa Lopes; Gouveia, Luísa; Reis, Alberto

    2014-02-01

    The production of microbial biofuels is currently under investigation, as they are alternative sources to fossil fuels, which are diminishing and their use has a negative impact on the environment. However, so far, biofuels derived from microbes are not economically competitive. One way to overcome this bottleneck is the use of microorganisms to transform substrates into biofuels and high value-added products, and simultaneously taking advantage of the various microbial biomass components to produce other products of interest, as an integrated process. In this way, it is possible to maximize the economic value of the whole process, with the desired reduction of the waste streams produced. It is expected that this integrated system makes the biofuel production economically sustainable and competitive in the near future. This review describes the investigation on integrated microbial processes (based on bacteria, yeast, and microalgal cultivations) that have been experimentally developed, highlighting the importance of this approach as a way to optimize microbial biofuel production process.

  1. Enabling fast electron transfer through both bacterial outer-membrane redox centers and endogenous electron mediators by polyaniline hybridized large-mesoporous carbon anode for high-performance microbial fuel cells

    International Nuclear Information System (INIS)

    Zou, Long; Qiao, Yan; Zhong, Canyu; Li, Chang Ming

    2017-01-01

    Both physical structure and chemical property of an electrode play critical roles in extracellular electron transfer from microbes to electrodes in microbial fuel cells (MFCs). Herein a novel polyaniline hybridized large mesoporous carbon (PANI-LMC) anode is fabricated from natural biomass by nanostructured CaCO 3 template-assisted carbonization followed by in situ chemical polymerizing PANI to enable fast extracellular electron transfer, in which the LMC with rich disorder-interconnected large mesopores (∼20−50 nm) and large surface area facilitates a fast mediated electron transfer through electron mediators, while the decorated PANI on LMC surface enables the direct electron transfer via bacterial outer-membrane redox centers. Owing to the unique synergistic effect from both excellent electron transfer paths, the PANI-LMC hybrid anode harvests high power electricity with a maximum output power density of 1280 mW m −2 in Shewanella putrefaciens CN32 MFCs, 10-fold higher than that of conventional carbon cloth. The findings from this work suggest a new insight on design of high-efficient anode according to the multiple and flexible electrochemical process for practical MFC applications.

  2. Global Processing Speed as a Mediator of Developmental Changes in Children's Auditory Memory Span

    Science.gov (United States)

    Ferguson, A.N.; Bowey, J.A.

    2005-01-01

    This study examined the role of global processing speed in mediating age increases in auditory memory span in 5- to 13-year-olds. Children were tested on measures of memory span, processing speed, single-word speech rate, phonological sensitivity, and vocabulary. Structural equation modeling supported a model in which age-associated increases in…

  3. Sustainable resource recovery and energy conversion processes using microbial electrochemical technologies

    Science.gov (United States)

    Yates, Matthew D.

    Microbial Electrochemical Technologies (METs) are emerging technological platforms for the conversion of waste into usable products. METs utilize naturally occurring bacteria, called exoelectrogens, capable of transferring electrons to insoluble terminal electron acceptors. Electron transfer processes in the exoelectrogen Geobacter sulfurreducens were exploited here to develop sustainable processes for synthesis of industrially and socially relevant end products. The first process examined was the removal of soluble metals from solution to form catalytic nanoparticles and nanoporous structures. The second process examined was the biocatalytic conversion of electrons into hydrogen gas using electrons supplied directly to an electrode. Nanoparticle formation is desirable because materials on the nanoscale possess different physical, optical, electronic, and mechanical properties compared to bulk materials. In the first process, soluble palladium was used to form catalytic palladium nanoparticles using extracellular electron transfer (EET) processes of G. sulfurreducens, typically the dominant member of mixedculture METs. Geobacter cells reduced the palladium extracellularly using naturally produced pili, which provided extracellular adsorption and reduction sites to help delay the diffusion of soluble metals into the cell. The extracellular reduction prevented cell inactivation due to formation of intracellular particles, and therefore the cells could be reused in multiple palladium reduction cycles. A G. sulfurreducens biofilm was next investigated as a biotemplate for the formation of a nanoporous catalytic palladium structure. G. sulfurreducens biofilms have a dense network of pili and extracellular cytochromes capable of high rates of electron transfer directly to an electrode surface. These pili and cytochromes provide a dense number of reduction sites for nanoparticle formation without the need for any synthetic components. The cells within the biofilm also can

  4. Insights into microbial communities mediating the bioremediation of hydrocarbon-contaminated soil from an Alpine former military site.

    Science.gov (United States)

    Siles, José A; Margesin, Rosa

    2018-05-01

    The study of microbial communities involved in soil bioremediation is important to identify the specific microbial characteristics that determine improved decontamination rates. Here, we characterized bacterial, archaeal, and fungal communities in terms of (i) abundance (using quantitative PCR) and (ii) taxonomic diversity and structure (using Illumina amplicon sequencing) during the bioremediation of long-term hydrocarbon-contaminated soil from an Alpine former military site during 15 weeks comparing biostimulation (inorganic NPK fertilization) vs. natural attenuation and considering the effect of temperature (10 vs. 20 °C). Although a considerable amount of total petroleum hydrocarbon (TPH) loss could be attributed to natural attenuation, significantly higher TPH removal rates were obtained with NPK fertilization and at increased temperature, which were related to the stimulation of the activities of indigenous soil microorganisms. Changing structures of bacterial and fungal communities significantly explained shifts in TPH contents in both natural attenuation and biostimulation treatments at 10 and 20 °C. However, archaeal communities, in general, and changing abundances and diversities in bacterial and fungal communities did not play a decisive role on the effectiveness of soil bioremediation. Gammaproteobacteria and Bacteroidia classes, within bacterial community, and undescribed/novel groups, within fungal community, proved to be actively involved in TPH removal in natural attenuation and biostimulation at both temperatures.

  5. Microbial processes and communities in sediment samples along a transect across the Lusi mud volcano, Indonesia

    Science.gov (United States)

    Krueger, Martin; Straaten, Nontje; Mazzini, Adriano

    2015-04-01

    The Lusi eruption represents one of the largest ongoing sedimentary hosted geothermal systems. This eruption started in 2006 following to a 6.3 M earthquake that stroke Java Island. Since then it has been spewing boiling mud from a central crater with peaks reaching 180.000 m3 per day. Today an area of about 8 km2 is covered by locally dried mud breccia where a network of hundreds of satellite seeping pools is active. Numerous investigations focused on the study of offshore microbial colonies that commonly thrive at offshore methane seeps and mud volcanoes, however very little has been done for onshore seeping structures. Lusi represents a unique opportunity to complete a comprehensive study of onshore microbial communities fed by the seepage of CH4 and CO2 as well as of heavier liquid hydrocarbons originating from several km below the surface. We conducted a sampling campaign at the Lusi site collecting samples of fresh mud close to the erupting crater using a remote controlled drone. In addition we completed a transect towards outer parts of the crater to collect older, weathered samples for comparison. In all samples active microorganisms were present. The highest activities for CO2 and CH4 production as well as for CH4 oxidation and hydrocarbon degradation were observed in medium-age mud samples collected roughly in the middle of the transect. Rates for aerobic methane oxidation were high, as was the potential of the microbial communities to degrade hydrocarbons (oils, alkanes, BTEX tested). The data suggests a transition of microbial populations from an anaerobic, hydrocarbon-driven metabolism in fresher samples from center or from small seeps to more generalistic, aerobic microbial communities in older, more consolidated sediments. Currently, the microbial communities in the different sediment samples are analyzed using quantitative PCR and T-RFLP combined with MiSeq sequencing. This study represents an initial step to better understand onshore seepage

  6. Changes in optical characteristics of surface microlayers hint to photochemically and microbially mediated DOM turnover in the upwelling region off the coast of Peru

    Science.gov (United States)

    Galgani, Luisa; Engel, Anja

    2016-04-01

    The coastal upwelling system off the coast of Peru is characterized by high biological activity and a pronounced subsurface oxygen minimum zone, as well as associated emissions of atmospheric trace gases such as N2O, CH4 and CO2. From 3 to 23 December 2012, R/V Meteor (M91) cruise took place in the Peruvian upwelling system between 4.59 and 15.4° S, and 82.0 to 77.5° W. During M91 we investigated the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like chromophoric dissolved organic matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. We analyzed SML and underlying water (ULW) samples at 38 stations focusing on CDOM spectral characteristics as indicator of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slope (S) values and excitation-emission matrix fluorescence (EEMs), which allow us to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources and sinks. Spectral slope S varied between 0.012 to 0.043 nm-1 and was quite similar between SML and ULW, with no significant differences between the two compartments. Higher S values were observed in the ULW of the southern stations below 15° S. By EEMs, we identified five fluorescent components (F1-5) of the CDOM pool, of which two had excitation/emission characteristics of amino-acid-like fluorophores (F1, F4) and were highly enriched in the SML, with a median ratio SML : ULW of 1.5 for both fluorophores. In the study region, values for CDOM absorption ranged from 0.07 to 1.47 m-1. CDOM was generally highly concentrated in the SML, with a median enrichment with respect to the ULW of 1.2. CDOM composition and changes in spectral slope properties suggested a local

  7. Markers of Microbial Translocation and Immune Activation Predict Cognitive Processing Speed in Heavy-Drinking Men Living with HIV

    Directory of Open Access Journals (Sweden)

    Mollie A. Monnig

    2017-09-01

    Full Text Available HIV infection and alcohol use disorder are associated with deficits in neurocognitive function. Emerging evidence points to pro-inflammatory perturbations of the gut-brain axis as potentially contributing to neurocognitive impairment in the context of HIV and chronic heavy alcohol use. This study examined whether plasma markers of microbial translocation (LPS from the gastrointestinal tract and related immune activation (sCD14, EndoCAb were associated with neurocognition in 21 men living with HIV who were virally suppressed on antiretroviral therapy. All participants met federal criteria for heavy drinking and were enrolled in a randomized controlled trial (RCT of a brief alcohol intervention. This secondary analysis utilized blood samples and cognitive scores (learning, memory, executive function, verbal fluency, and processing speed obtained at baseline and three-month follow-up of the RCT. In generalized estimating equation models, LPS, sCD14, and EndoCAb individually were significant predictors of processing speed. In a model with all biomarkers, higher LPS and sCD14 both remained significant predictors of lower processing speed. These preliminary findings suggest that inflammation stemming from HIV and/or alcohol could have negative effects on the gut-brain axis, manifested as diminished processing speed. Associations of microbial translocation and immune activation with processing speed in heavy-drinking PLWH warrant further investigation in larger-scale studies.

  8. Information processing speed as a mediator between psychosocial stress and global cognition in older adults.

    Science.gov (United States)

    Foong, Hui F; Hamid, Tengku A; Ibrahim, Rahimah; Haron, Sharifah A

    2018-01-01

    The link between psychosocial stress and cognitive function is complex, and previous studies have indicated that it may be mediated by processing speed. Therefore, the main aim of this study was to examine whether processing speed mediates the association between psychosocial stress and global cognition in older adults. Moreover, the moderating role of gender in this model is examined as well. The study included 2322 community-dwelling older adults in Malaysia who were randomly selected through a multistage proportional cluster random sampling technique. Global cognition construct was measured by the Mini-Mental State Examination and Montreal Cognitive Assessment; psychosocial stress construct was measured by perceived stress, depression, loneliness, and neuroticism; and processing speed was assessed by the Digit Symbol Substitution Test. Structural equation modelling was used to analyze the mediation and moderation tests. Processing speed was found to partially mediate the relationship between psychosocial stress and global cognition (β in the direct model = -0.15, P cognition was found to be significant in men only, whereas the association between processing speed and global cognition was significant in men and women. Psychosocial stress may increase the likelihood that older adults will experience poor processing capacity, which could reduce their higher level cognition. Results indicate that there is a need to develop processing capacity intervention programmes for psychologically distressed older adults to prevent them from suffering cognitive decline. © 2018 Japanese Psychogeriatric Society.

  9. Material mediation and embodied actions in collaborative design process

    Directory of Open Access Journals (Sweden)

    Henna Lahti

    2016-02-01

    Full Text Available Material and embodied practices are an intrinsic part of craft and design education. This article reports a study in which textile teacher-students designed three-dimensional toys based on children’s drawings. Three students in each team worked on the given materials and designed the shape of the toy together. Materials for designing were either: 1 pen and paper, 2 masking tape and thin cardboard, or 3 wire and non-woven interfacing fabric. After the modelling phase, the final toys were created by sewing. Research data consisted of the video recordings of three design sessions representing the various design materials given to the students. By conducting multiple levels of analysis, we examined how the participants used materials and gestures to support their communication. The results highlight the strengths of 3D modelling techniques, particularly through comparison with the drawing technique undertaken by one design team. We found that simple material tools support students’ design process and suggest this could be applied to other design settings.

  10. Ageing processes and soil microbial community effects on the biodegradation of soil 13C-2,4-D nonextractable residues

    International Nuclear Information System (INIS)

    Lerch, T.Z.; Dignac, M.-F.; Nunan, N.; Barriuso, E.; Mariotti, A.

    2009-01-01

    The biodegradation of nonextractable residues (NER) of pesticides in soil is still poorly understood. The aim of this study was to evaluate the influence of NER ageing and fresh soil addition on the microbial communities responsible for their mineralisation. Soil containing either 15 or 90-day-old NER of 13 C-2,4-D (NER15 and NER90, respectively) was incubated for 90 days with or without fresh soil. The addition of fresh soil had no effect on the mineralisation of NER90 or of SOM, but increased the extent and rate of NER15 mineralisation. The analyses of 13 C-enriched FAME (fatty acids methyl esters) profiles showed that the fresh soil amendment only influenced the amount and structure of microbial populations responsible for the biodegradation of NER15. By coupling biological and chemical analyses, we gained some insight into the nature and the biodegradability of pesticide NER. - Ageing processes influence the NER mineralisation rate and the microbial population involved.

  11. Deriving site-specific soil clean-up values for metals and metalloids: rationale for including protection of soil microbial processes.

    Science.gov (United States)

    Kuperman, Roman G; Siciliano, Steven D; Römbke, Jörg; Oorts, Koen

    2014-07-01

    Although it is widely recognized that microorganisms are essential for sustaining soil fertility, structure, nutrient cycling, groundwater purification, and other soil functions, soil microbial toxicity data were excluded from the derivation of Ecological Soil Screening Levels (Eco-SSL) in the United States. Among the reasons for such exclusion were claims that microbial toxicity tests were too difficult to interpret because of the high variability of microbial responses, uncertainty regarding the relevance of the various endpoints, and functional redundancy. Since the release of the first draft of the Eco-SSL Guidance document by the US Environmental Protection Agency in 2003, soil microbial toxicity testing and its use in ecological risk assessments have substantially improved. A wide range of standardized and nonstandardized methods became available for testing chemical toxicity to microbial functions in soil. Regulatory frameworks in the European Union and Australia have successfully incorporated microbial toxicity data into the derivation of soil threshold concentrations for ecological risk assessments. This article provides the 3-part rationale for including soil microbial processes in the development of soil clean-up values (SCVs): 1) presenting a brief overview of relevant test methods for assessing microbial functions in soil, 2) examining data sets for Cu, Ni, Zn, and Mo that incorporated soil microbial toxicity data into regulatory frameworks, and 3) offering recommendations on how to integrate the best available science into the method development for deriving site-specific SCVs that account for bioavailability of metals and metalloids in soil. Although the primary focus of this article is on the development of the approach for deriving SCVs for metals and metalloids in the United States, the recommendations provided in this article may also be applicable in other jurisdictions that aim at developing ecological soil threshold values for protection of

  12. MbT-Tool: An open-access tool based on Thermodynamic Electron Equivalents Model to obtain microbial-metabolic reactions to be used in biotechnological process.

    Science.gov (United States)

    Araujo, Pablo Granda; Gras, Anna; Ginovart, Marta

    2016-01-01

    Modelling cellular metabolism is a strategic factor in investigating microbial behaviour and interactions, especially for bio-technological processes. A key factor for modelling microbial activity is the calculation of nutrient amounts and products generated as a result of the microbial metabolism. Representing metabolic pathways through balanced reactions is a complex and time-consuming task for biologists, ecologists, modellers and engineers. A new computational tool to represent microbial pathways through microbial metabolic reactions (MMRs) using the approach of the Thermodynamic Electron Equivalents Model has been designed and implemented in the open-access framework NetLogo. This computational tool, called MbT-Tool (Metabolism based on Thermodynamics) can write MMRs for different microbial functional groups, such as aerobic heterotrophs, nitrifiers, denitrifiers, methanogens, sulphate reducers, sulphide oxidizers and fermenters. The MbT-Tool's code contains eighteen organic and twenty inorganic reduction-half-reactions, four N-sources (NH4 (+), NO3 (-), NO2 (-), N2) to biomass synthesis and twenty-four microbial empirical formulas, one of which can be determined by the user (CnHaObNc). MbT-Tool is an open-source program capable of writing MMRs based on thermodynamic concepts, which are applicable in a wide range of academic research interested in designing, optimizing and modelling microbial activity without any extensive chemical, microbiological and programing experience.

  13. MbT-Tool: An open-access tool based on Thermodynamic Electron Equivalents Model to obtain microbial-metabolic reactions to be used in biotechnological process

    Directory of Open Access Journals (Sweden)

    Pablo Araujo Granda

    2016-01-01

    Full Text Available Modelling cellular metabolism is a strategic factor in investigating microbial behaviour and interactions, especially for bio-technological processes. A key factor for modelling microbial activity is the calculation of nutrient amounts and products generated as a result of the microbial metabolism. Representing metabolic pathways through balanced reactions is a complex and time-consuming task for biologists, ecologists, modellers and engineers. A new computational tool to represent microbial pathways through microbial metabolic reactions (MMRs using the approach of the Thermodynamic Electron Equivalents Model has been designed and implemented in the open-access framework NetLogo. This computational tool, called MbT-Tool (Metabolism based on Thermodynamics can write MMRs for different microbial functional groups, such as aerobic heterotrophs, nitrifiers, denitrifiers, methanogens, sulphate reducers, sulphide oxidizers and fermenters. The MbT-Tool's code contains eighteen organic and twenty inorganic reduction-half-reactions, four N-sources (NH4+, NO3−, NO2−, N2 to biomass synthesis and twenty-four microbial empirical formulas, one of which can be determined by the user (CnHaObNc. MbT-Tool is an open-source program capable of writing MMRs based on thermodynamic concepts, which are applicable in a wide range of academic research interested in designing, optimizing and modelling microbial activity without any extensive chemical, microbiological and programing experience.

  14. Microbial processes in North Atlantic pelagic sediments, and potential risks of deep-sea waste disposal

    International Nuclear Information System (INIS)

    Bolliger, R.; Hanselmann, K.W.; Bachofen, R.

    1989-01-01

    From the results for waste disposal on deep sea sediments, it was concluded: As waste canisters are buried in the sediment to a depth of 15 to 20 cm, they are in contact with the zone that contains the highest potential bacterial activity through a relatively large surface. An input of oxidizable organic matter to the sediment surface zone will stimulate microbial activity and therefore increase the risk for solubilization and redistribution of elements in the ocean water. Waste canisters lying on the sediment surface cut off the oxygen supply from the ocean water and ease the shift to anaerobiosis. This initiates microbial activities through which metals are changed into their mobile species as a consequence of the altered environmental redox potential. The risk for steel corrosion by hydrogen sulfide, which could be produced by sulfate reducing bacteria, is minimal since this physiological group is not active in the North Atlantic sediments examined

  15. Effect of continuous oleate addition on microbial communities involved in anaerobic digestion process

    DEFF Research Database (Denmark)

    Baserba, Manel Garrido; Angelidaki, Irini; Karakashev, Dimitar Borisov

    2012-01-01

    bacterial consortium related to functional specialization of the species towards oleate degradation. For the archaeal domain, the sequences were affiliated within Euryarchaeota phylum with three major groups (Methanosarcina, Methanosaeta and Methanobacterium genera). Results obtained in this study deliver...... a comprehensive picture on oleate degrading microbial communities in high organic strength wastewater. The findings might be utilized for development of strategies for biogas production from lipid-riched wastes....

  16. Effects of engineered nanomaterials on microbial catalyzed biogeochemical processes in sediments

    Energy Technology Data Exchange (ETDEWEB)

    Gao Jie, E-mail: jgao@perc.ufl.edu [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); Wang Yu; Hovsepyan, Anna [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); Bonzongo, Jean-Claude J., E-mail: bonzongo@ufl.edu [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States)

    2011-02-15

    Engineered nanomaterials (ENMs) are anticipated to find use in many human activities and commercial products. Concerns are therefore being raised regarding their environmental fate and toxicological implications, which remain largely unknown. In this study, we investigate the effects of C{sub 60}, nano-Ag and CdSe quantum dots (QD) on microbial-catalyzed oxidation of organic matter in freshwater sediments. Sediment slurries spiked with sodium acetate at a final concentration of 150 mg/L were separately treated with pre-identified toxic levels of the tested ENMs. The study focused primarily on acetate oxidation by nitrate reducing bacteria. Sediment slurries were incubated under anaerobic conditions in parallel with control samples, and changes in concentrations of acetate, nitrate and nitrite tracked over time. The results showed that tested C{sub 60} concentration completely inhibited the microbial oxidation of acetate, whereas the addition of nano-Ag and CdSe QD to sediment slurries negatively affected the rates of acetate oxidation. Under conditions with nitrate as prevalent electron acceptor, reaction rates of acetate degradation decreased from 0.44 day{sup -1} in control slurries to 0.24 day{sup -1} and 0.20 day{sup -1} in slurries treated with nano-Ag and CdSe QD, respectively. These preliminary results call for further investigations on potential long-term effects of ENMs on microbial driven basic ecosystem services.

  17. Microbial ecology of hot desert edaphic systems.

    Science.gov (United States)

    Makhalanyane, Thulani P; Valverde, Angel; Gunnigle, Eoin; Frossard, Aline; Ramond, Jean-Baptiste; Cowan, Don A

    2015-03-01

    A significant proportion of the Earth's surface is desert or in the process of desertification. The extreme environmental conditions that characterize these areas result in a surface that is essentially barren, with a limited range of higher plants and animals. Microbial communities are probably the dominant drivers of these systems, mediating key ecosystem processes. In this review, we examine the microbial communities of hot desert terrestrial biotopes (including soils, cryptic and refuge niches and plant-root-associated microbes) and the processes that govern their assembly. We also assess the possible effects of global climate change on hot desert microbial communities and the resulting feedback mechanisms. We conclude by discussing current gaps in our understanding of the microbiology of hot deserts and suggest fruitful avenues for future research. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Microbial effects

    International Nuclear Information System (INIS)

    Sharpe, V.J.

    1985-10-01

    The long term safety and integrity of radioactive waste disposal sites proposed for use by Ontario Hydro may be affected by the release of radioactive gases. Microbes mediate the primary pathways of waste degradation and hence an assessment of their potential to produce gaseous end products from the breakdown of low level waste was performed. Due to a number of unknown variables, assumptions were made regarding environmental and waste conditions that controlled microbial activity; however, it was concluded that 14 C and 3 H would be produced, albeit over a long time scale of about 1500 years for 14 C in the worst case situation

  19. Succession of microbial community and enhanced mechanism of a ZVI-based anaerobic granular sludge process treating chloronitrobenzenes wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Liang, E-mail: felix79cn@hotmail.com [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou 310058 (China); Jin, Jie [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Lin, Haizhuan [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Wenzhou Environmental Protection Design Scientific Institute, Wenzhou 325000 (China); Gao, Kaituo [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Xu, Xiangyang, E-mail: xuxy@zju.edu.cn [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou 310058 (China)

    2015-03-21

    Highlights: • The combined ZVI–UASB process was established for the degradation of chloronitrobenzenes. • There were the better shock resistance and buffering capacity for anaerobic acidification in the combined process. • Novel ZVI-based anaerobic granular sludge (ZVI–AGS) was successfully developed. • Adaptive shift of microbial community was significant in ZVI-based anaerobic granular sludge system. - Abstract: The combined zero-valent iron (ZVI) and upflow anaerobic sludge blanket (UASB) process is established for the treatment of chloronitrobenzenes (ClNBs) wastewater, and the succession of microbial community and its enhanced mechanism are investigated in the study. Results showed that compared with the control UASB (R1), the stable COD removal, ClNBs transformation, and dechlorination occurred in the combined system (R2) when operated at influent COD and 3,4-Dichloronitrobenzene (3,4-DClNB) loading rates of 4200–7700 g m{sup −3} d{sup −1} and 6.0–70.0 g m{sup −3} d{sup −1}, and R2 had the better shock resistance and buffering capacity for the anaerobic acidification. The dechlorination for the intermediate products of p-chloroanaline (p-ClAn) to analine (AN) occurred in R2 reactor after 45 days, whereas it did not occur in R1 after a long-term operation. The novel ZVI-based anaerobic granular sludge (ZVI–AGS) was successfully developed in the combined system, and higher microbial activities including ClNB transformation and H{sub 2}/CH{sub 4} production were achieved simultaneously. The dominant bacteria were closely related to the groups of Megasphaera, Chloroflexi, and Clostridium, and the majority of archaea were correlated with the groups of Methanosarcinalesarchaeon, Methanosaetaconcilii, and Methanothrixsoehngenii, which are capable of reductively dechlorinating PCB, HCB, and TCE in anaerobic niche and EPS secretion.

  20. Succession of microbial community and enhanced mechanism of a ZVI-based anaerobic granular sludge process treating chloronitrobenzenes wastewater

    International Nuclear Information System (INIS)

    Zhu, Liang; Jin, Jie; Lin, Haizhuan; Gao, Kaituo; Xu, Xiangyang

    2015-01-01

    Highlights: • The combined ZVI–UASB process was established for the degradation of chloronitrobenzenes. • There were the better shock resistance and buffering capacity for anaerobic acidification in the combined process. • Novel ZVI-based anaerobic granular sludge (ZVI–AGS) was successfully developed. • Adaptive shift of microbial community was significant in ZVI-based anaerobic granular sludge system. - Abstract: The combined zero-valent iron (ZVI) and upflow anaerobic sludge blanket (UASB) process is established for the treatment of chloronitrobenzenes (ClNBs) wastewater, and the succession of microbial community and its enhanced mechanism are investigated in the study. Results showed that compared with the control UASB (R1), the stable COD removal, ClNBs transformation, and dechlorination occurred in the combined system (R2) when operated at influent COD and 3,4-Dichloronitrobenzene (3,4-DClNB) loading rates of 4200–7700 g m −3 d −1 and 6.0–70.0 g m −3 d −1 , and R2 had the better shock resistance and buffering capacity for the anaerobic acidification. The dechlorination for the intermediate products of p-chloroanaline (p-ClAn) to analine (AN) occurred in R2 reactor after 45 days, whereas it did not occur in R1 after a long-term operation. The novel ZVI-based anaerobic granular sludge (ZVI–AGS) was successfully developed in the combined system, and higher microbial activities including ClNB transformation and H 2 /CH 4 production were achieved simultaneously. The dominant bacteria were closely related to the groups of Megasphaera, Chloroflexi, and Clostridium, and the majority of archaea were correlated with the groups of Methanosarcinalesarchaeon, Methanosaetaconcilii, and Methanothrixsoehngenii, which are capable of reductively dechlorinating PCB, HCB, and TCE in anaerobic niche and EPS secretion

  1. Fermented liquid feed - Feed processing has a big impact on microbial degradation of free lysine during fermentation

    DEFF Research Database (Denmark)

    Canibe, Nuria; Jensen, Bent Borg

    2010-01-01

    In order to investigate the influence of feed processing on the microbial degradation of free lysine during fermentation of liquid feed, a study at laboratory scale was carried out. Based on a standard Danish grower diet with extra free amino acids added, two treatments were prepared: treatment 1...... a few hours of fermentation, the levels in both treatments became similar. The concentration of acetic acid was higher in the mixture containing the mash feed than in that containing the pelleted feed. The disappearance of free lysine was much higher when mash feed was fermented than when the same...

  2. Mediating factors of coping process in parents of children with type 1 diabetes.

    Science.gov (United States)

    Oskouie, Fatemeh; Mehrdad, Neda; Ebrahimi, Hossein

    2013-05-14

    Type 1 diabetes is a lifelong condition for children and their parents, the management for which imposes a vast responsibility. This study explores the mediating factors that affect Iranian parents' coping processes with their children's type 1 diabetes. Research was conducted using the grounded theory method. Participants were selected purposefully, and we continued with theoretical sampling. Constant comparative analysis was used to analyze the data. The mediating factors of the parental coping process with their child's diabetes consist of the child's cooperation, crises and experiences, economic challenges, and parental participation in care. Findings highlight the necessity of well-informed nurses with insightful understanding of the mediating factors in parental coping with juvenile diabetes in order to meet the particular needs of this group.

  3. New concepts of microbial treatment processes for the nitrogen removal: effect of protein and amino acids degradation.

    Science.gov (United States)

    González-Martínez, Alejandro; Calderón, Kadiya; González-López, Jesús

    2016-05-01

    High concentrations of proteins and amino acids can be found in wastewater and wastewater stream produced in anaerobic digesters, having shown that amino acids could persist over different managements for nitrogen removal affecting the nitrogen removal processes. Nitrogen removal is completely necessary because of their implications and the significant adverse environmental impact of ammonium such as eutrophication and toxicity to aquatic life on the receiving bodies. In the last decade, the treatment of effluents with high ammonium concentration through anammox-based bioprocesses has been enhanced because these biotechnologies are cheaper and more environmentally friendly than conventional technologies. However, it has been shown that the presence of important amounts of proteins and amino acids in the effluents seriously affects the microbial autotrophic consortia leading to important losses in terms of ammonium oxidation efficiency. Particularly the presence of sulfur amino acids such as methionine and cysteine has been reported to drastically decrease the autotrophic denitrification processes as well as affect the microbial community structure promoting the decline of ammonium oxidizing bacteria in favor of other phylotypes. In this context we discuss that new biotechnological processes that improve the degradation of protein and amino acids must be considered as a priority to increase the performance of the autotrophic denitrification biotechnologies.

  4. First evaluation of alkylpyrazine application as a novel method to decrease microbial contaminations in processed meat products.

    Science.gov (United States)

    Schöck, Matthias; Liebminger, Stefan; Berg, Gabriele; Cernava, Tomislav

    2018-04-03

    Every year about 20% of the globally produced meat gets lost due to microbial spoilage. Nevertheless, the demand for processed meat is constantly rising and producers are searching for novel strategies to reduce microbial contaminations in their products. In the present study, we evaluated the applicability of alkylpyrazines as antimicrobial agents. These fragrant molecules naturally occur in different vegetables, fruits, roasted nut and meat. Several pyrazine derivatives are readily added to processed products for flavoring purposes in the food industry. To evaluate their potential for application, two derivatives were tested for their antimicrobial activity against meat-associated bacterial contaminants and chicken meat as a whole. Isolates assigned to Carnobacteriaceae, Enterobacteriaceae, Listeriaceae, and Moraxellaceae were substantially inhibited in the pilot tests. Moreover, treatments of pyrazine-susceptible isolates resulted in 4-log reductions in bacterial cell counts. The effect was more pronounced when the model contaminants were exposed to higher concentrations of 5-isobutyl-2,3-dimethylpyrazine. In a first small-scale application with processed chicken meat, it was demonstrated that the antimicrobial effects of 2-isobutyl-3-methylpyrazine can be improved by additionally lowering the water activity on the meat surface when maltodextrin is used as a carrier substance. At low pyrazine dosages, the number of viable bacteria was decreased up to 95% in comparison to the corresponding controls. A complementary imaging method that was developed to assess the efficacy on the product, reinforced the applicability of this two-component system.

  5. Characterization of microbial community in the two-stage process for hydrogen and methane production from food waste

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Chun-Feng [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Ebie, Yoshitaka [National Institute for Environmental Studies, Tsukuba 305-8506 (Japan); Xu, Kai-Qin [National Institute for Environmental Studies, Tsukuba 305-8506 (Japan); State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072 (China); Li, Yu-You [Department of Civil and Environmental Engineering, Tohoku University, Sendai 980-8579 (Japan); Inamori, Yuhei [Faculty of Symbiotic Systems Science, Fukushima University, Fukushima 960-1296 (Japan)

    2010-08-15

    The structure of a microbial community in the two-stage process for H{sub 2} and CH{sub 4} production from food waste was investigated by a molecular biological approach. The process was a continuous combined thermophilic acidogenic hydrogenesis and mesophilic (RUN1) or thermophilic (RUN2) methanogenesis with recirculation of the digested sludge. A two-phase process suggested in this study effectively separate H{sub 2}-producing bacteria from methanogenic archaea by optimization of design parameters such as pH, hydraulic retention time (HRT) and temperature. Galore microbial diversity was found in the thermophilic acidogenic hydrogenesis, Clostridium sp. strain Z6 and Thermoanaerobacterium thermosaccharolyticum were considered to be the dominant thermophilic H{sub 2}-producing bacteria. The hydrogenotrophic methanogens were inhibited in thermophilic methanogenesis, whereas archaeal rDNAs were higher in the thermophilic methanogenesis than those in mesophilic methanogenesis. The yields of H{sub 2} and CH{sub 4} were in equal range depending on the characteristics of food waste, whereas effluent water quality indicators were different obviously in RUN1 and RUN2. The results indicated that hydrolysis and removal of food waste were higher in RUN2 than RUN1. (author)

  6. Optimization of water curing for the preservation of chestnuts (Castanea sativa Mill.) and evaluation of microbial dynamics during process.

    Science.gov (United States)

    Blaiotta, Giuseppe; Di Capua, Marika; Romano, Annalisa; Coppola, Raffaele; Aponte, Maria

    2014-09-01

    Chestnuts are very perishable fruits, whose quality may be compromised during postharvest handling. Damage can be caused both by insects and fungi. Water curing, a commonly used postharvest method, is based on soaking fruits in water typically for about one week. Factors that affect effectiveness of water curing have only been explained partially. A decrease in pH, likely imputable to a light fermentation caused by lactic acid bacteria, may inhibit the growth of moulds. In this study a Lactobacillus pentosus strain was selected for its ability to inhibit fungi, and used as a starter culture during water curing. As second goal, a reduction of the environmental impact of the process was evaluated by using water that had been re-cycled from a previous curing treatment. Experiments were performed on pilot as well as on farm scale. In all trials, microbial dynamics were evaluated by means of a polyphasic approach including conventional and molecular-based analyses. According to results, the employment of an adjunct culture appears as a very promising opportunity. Even if no reduction in the duration of the process was achieved, waters exhibited a minor microbial complexity and fruits did not lose the natural lustre after the process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Changes in optical characteristics of surface microlayers in the Peruvian upwelling region hint to photochemically and microbially-mediated DOM turnover

    Science.gov (United States)

    Engel, A.; Galgani, L.

    2016-02-01

    The coastal upwelling system off Peru is characterized by high biological activity and associated subsurface oxygen minimum zone, leading to an enhanced emission of atmospheric trace gases. High biological productivity in the water column may promote the establishment of enriched organic surface films, key environments for processes regulating gas fluxes across the water-air interface. During M91 cruise to the Peruvian upwelling, we focused our attention on the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like Chromophoric Dissolved Organic Matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. In order to understand organic matter cycling in surface films, we analyzed SML and underlying water samples in 38 stations determining DOC concentrations, amino acids composition, marine gels, CDOM and bacterial abundance as indicators of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slopes (S) values and Excitation-Emission Matrix fluorescence (EEMs), which allow to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources. Profound changes in spectral slope properties were observed suggesting smaller MW CDOM in the SML compared to underlying water. Microbial and photochemical degradation are likely the main drivers for organic matter cycling in the top layer of the ocean. Consequences on the formation of inorganic and organic species highly relevant for air-sea gas exchange and for climate dynamics will be discussed.

  8. Processes of microbial pesticide degradation in rapid sand filters for treatment of drinking water

    DEFF Research Database (Denmark)

    Hedegaard, Mathilde Jørgensen; Albrechtsen, Hans-Jørgen

    Aerobic rapid sand filters for treatment of groundwater at waterworks were investigated for the ability to remove pesticides. The potential, kinetics and mechanisms of microbial pesticide removal was investigated in microcosms consisting of filter sand, treated water and pesticides in initial...... concentrations of 0.04-2.4 μg/L. The pesticides were removed from the water in microcosms with filter sand from all three investigated sand filters. Within the experimental periode of six to 13 days, 65-85% of the bentazone, 86-93% of the glyphosate, 97-99% of the p-nitrophenol was removed from the water phase...

  9. Methane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzle.

    Science.gov (United States)

    Detman, Anna; Mielecki, Damian; Pleśniak, Łukasz; Bucha, Michał; Janiga, Marek; Matyasik, Irena; Chojnacka, Aleksandra; Jędrysek, Mariusz-Orion; Błaszczyk, Mieczysław K; Sikora, Anna

    2018-01-01

    Anaerobic digestion, whose final products are methane and carbon dioxide, ensures energy flow and circulation of matter in ecosystems. This naturally occurring process is used for the production of renewable energy from biomass. Lactate, a common product of acidic fermentation, is a key intermediate in anaerobic digestion of biomass in the environment and biogas plants. Effective utilization of lactate has been observed in many experimental approaches used to study anaerobic digestion. Interestingly, anaerobic lactate oxidation and lactate oxidizers as a physiological group in methane-yielding microbial communities have not received enough attention in the context of the acetogenic step of anaerobic digestion. This study focuses on metabolic transformation of lactate during the acetogenic and methanogenic steps of anaerobic digestion in methane-yielding bioreactors. Methane-yielding microbial communities instead of pure cultures of acetate producers were used to process artificial lactate-rich media to methane and carbon dioxide in up-flow anaerobic sludge blanket reactors. The media imitated the mixture of acidic products found in anaerobic environments/digesters where lactate fermentation dominates in acidogenesis. Effective utilization of lactate and biogas production was observed. 16S rRNA profiling was used to examine the selected methane-yielding communities. Among Archaea present in the bioreactors, the order Methanosarcinales predominated. The acetoclastic pathway of methane formation was further confirmed by analysis of the stable carbon isotope composition of methane and carbon dioxide. The domain Bacteria was represented by Bacteroidetes , Firmicutes , Proteobacteria , Synergistetes , Actinobacteria , Spirochaetes , Tenericutes , Caldithrix , Verrucomicrobia , Thermotogae , Chloroflexi , Nitrospirae, and Cyanobacteria. Available genome sequences of species and/or genera identified in the microbial communities were searched for genes encoding the lactate

  10. Diets high in resistent starch and arabinoxylan modulate digestion processes and SCFA pool size in the large intestine and faecal microbial composition in pigs

    DEFF Research Database (Denmark)

    Nielsen, Tina Skau; Lærke, Helle Nygaard; Theil, Peter Kappel

    2014-01-01

    The effects of a high level of dietary fibre (DF) either as arabinoxylan (AX) or resistant starch (RS) on digestion processes, SCFA concentration and pool size in various intestinal segments and on the microbial composition in the faeces were studied in a model experiment with pigs. A total...... resulted in a 3- to 5-fold higher pool size of butyrate compared with WSD feeding, with the RSD being intermediate (P microbial composition towards butyrogenic...

  11. Styles of International Mediation in Peace Processes Between States and Terrorist Organizations

    Science.gov (United States)

    2016-06-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited STYLES OF...Office of Management and Budget, Paperwork Reduction Project (0704-0188) Washington, DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE...June 2016 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE STYLES OF INTERNATIONAL MEDIATION IN PEACE PROCESSES BETWEEN

  12. Emotion Regulation and Aggressive Behavior in Preschoolers: The Mediating Role of Social Information Processing

    Science.gov (United States)

    Helmsen, Johanna; Koglin, Ute; Petermann, Franz

    2012-01-01

    This study examined whether the relation between maladaptive emotion regulation and aggression was mediated by deviant social information processing (SIP). Participants were 193 preschool children. Emotion regulation and aggression were rated by teachers. Deviant SIP (i.e., attribution of hostile intent, aggressive response generation, aggressive…

  13. Defining Business Communication Using the Movie "The Insider" as Mediator of Students' Thought Processes.

    Science.gov (United States)

    Rodriguez-Talavera, Leticia

    Business communication is different from other domains in that its contextual meaning requires previous metacognitive mediation of signs. The communicative process in business is aimed at accomplishing a specific outcome. Various forms of meaning come into play in business communication such as denotative, connotative, stylistic, affective,…

  14. Myelin Breakdown Mediates Age-Related Slowing in Cognitive Processing Speed in Healthy Elderly Men

    Science.gov (United States)

    Lu, Po H.; Lee, Grace J.; Tishler, Todd A.; Meghpara, Michael; Thompson, Paul M.; Bartzokis, George

    2013-01-01

    Background: To assess the hypothesis that in a sample of very healthy elderly men selected to minimize risk for Alzheimer's disease (AD) and cerebrovascular disease, myelin breakdown in late-myelinating regions mediates age-related slowing in cognitive processing speed (CPS). Materials and methods: The prefrontal lobe white matter and the genu of…

  15. The psychological aftermath of bereavement : Risk factors, mediating processes, and intervention

    NARCIS (Netherlands)

    Van der Houwen, H.K.

    2009-01-01

    In this dissertation some of the major facets associated with the psychological effects of bereavement were the subject of investigation: risk factors, mediating processes and intervention. Previous research on risk factors is limited because of a number of methodological shortcomings: a focus on

  16. Information Processing Versus Social Cognitive Mediators of Weight Loss in a Podcast-Delivered Health Intervention

    Science.gov (United States)

    Ko, Linda K.; Turner-McGrievy, Gabrielle M.; Campbell, Marci K.

    2014-01-01

    Podcasting is an emerging technology, and previous interventions have shown promising results using theory-based podcast for weight loss among overweight and obese individuals. This study investigated whether constructs of social cognitive theory and information processing theories (IPTs) mediate the effect of a podcast intervention on weight loss…

  17. The Mediating Role of Psychosocial Benefits in the Satisfaction Formation Process

    NARCIS (Netherlands)

    O. Prevo; P. Leunisse; H. Roest (Henk)

    1999-01-01

    textabstractIn this paper we investigate the mediating role of psychosocial benefits in the customer satisfaction/dissatisfaction formation process. Most research on this subject deals with the causality direction of psychosocial benefits and satisfaction, sometimes preceded by an overall functional

  18. Self-Regulatory Processes Mediate the Intention-Behavior Relation for Adherence and Exercise Behaviors

    NARCIS (Netherlands)

    Bruin, de M.; Sheeran, P.; Kok, G.; Hiemstra, A.; Prins, J.M.; Hospers, H.J.; Breukelen, G.J.P.

    2012-01-01

    Objectives: Understanding the gap between people's intentions and actual health behavior is an important issue in health psychology. Our aim in this study was to investigate whether self-regulatory processes (monitoring goal progress and responding to discrepancies) mediate the intention-behavior

  19. Back from the brink: The 2008 mediation process and reforms in ...

    African Journals Online (AJOL)

    Book review. Back from the brink: The 2008 mediation process and reforms in. Kenya. Graça Machel and Benjamin Mkapa 2014. Geneva, African Union Commission, 310 pages. ISBN 978-9966-065-73-5. Reviewed by Charles Nyuykonge. Senior Researcher: Knowledge Production Department, ACCORD. Although much ...

  20. Understanding the core of RNA interference: The dynamic aspects of Argonaute-mediated processes

    KAUST Repository

    Zhu, Lizhe; Jiang, Hanlun; Sheong, Fu Kit; Cui, Xuefeng; Wang, Yanli; Gao, Xin; Huang, Xuhui

    2016-01-01

    and its interaction with the nucleic acids, considerable progress has been made to reveal the dynamic aspects of various Ago-mediated processes. Here we review these novel insights into the guide-strand loading, duplex unwinding, and effects of seed

  1. Mediating Justice: Women's Perceptions of Fairness in the Civil Protection Order Process.

    Science.gov (United States)

    Hefner, M Kristen; Baboolal, Aneesa A; Fleury-Steiner, Ruth E; Miller, Susan L

    2018-05-01

    Mediation use has grown rapidly in the past few decades as an efficacious method of civil dispute resolution. However, early research suggests that civil mediation may cause further harm to victims of intimate partner abuse because, based on the inherent power dynamics of abusive relationships, they are not able to effectively advocate on their own behalf. In addition, organizational efficiency concerns have led to the development of consent processes for civil protection orders (POs). However, research has yet to examine the extent to which victims of intimate partner violence who take part in these consent processes perceive the process and associated outcomes as fair. Using qualitative data ( N = 19 interviews) collected from women who sought civil POs through Family Court in Delaware, this research finds that the consent process and women's interactions with mediators reproduce power inequalities that are inherent in cases of intimate partner abuse, which shape their perceptions of fairness in the PO process and outcomes. Victims being silenced and disempowered throughout the consent process results in cumulative effects-similar tactics used by batterers-which continue to leave victims vulnerable. In addition, the power asymmetry victims experience in abusive relationships is replicated by the legal institution and court structure in terms of not having access to attorneys, not receiving guidance and advocacy, and, at times, experiencing insensitive treatment. Thus, this study provides insight into the inequalities present within the PO consent process that can create further harm to victims.

  2. Next-generation sequencing (NGS) for assessment of microbial water quality: current progress, challenges, and future opportunities

    OpenAIRE

    BoonFei eTan; Charmaine Marie Ng; Jean Pierre Nshimyimana; Jean Pierre Nshimyimana; Lay-Leng eLoh; Lay-Leng eLoh; Karina Yew-Hoong Gin; Janelle Renee Thompson; Janelle Renee Thompson

    2015-01-01

    Water quality is an emergent property of a complex system comprised of interacting microbial populations and introduced microbial and chemical contaminants. Studies leveraging next-generation sequencing (NGS) technologies are providing new insights into the ecology of microbially mediated processes that influence fresh water quality such as algal blooms, contaminant biodegradation, and pathogen dissemination. In addition, sequencing methods targeting small subunit (SSU) rRNA hypervariable reg...

  3. Thousands of microbial genomes shed light on interconnected biogeochemical processes in an aquifer system

    Science.gov (United States)

    Anantharaman, Karthik; Brown, Christopher T.; Hug, Laura A.; Sharon, Itai; Castelle, Cindy J.; Probst, Alexander J.; Thomas, Brian C.; Singh, Andrea; Wilkins, Michael J.; Karaoz, Ulas; Brodie, Eoin L.; Williams, Kenneth H.; Hubbard, Susan S.; Banfield, Jillian F.

    2016-01-01

    The subterranean world hosts up to one-fifth of all biomass, including microbial communities that drive transformations central to Earth's biogeochemical cycles. However, little is known about how complex microbial communities in such environments are structured, and how inter-organism interactions shape ecosystem function. Here we apply terabase-scale cultivation-independent metagenomics to aquifer sediments and groundwater, and reconstruct 2,540 draft-quality, near-complete and complete strain-resolved genomes that represent the majority of known bacterial phyla as well as 47 newly discovered phylum-level lineages. Metabolic analyses spanning this vast phylogenetic diversity and representing up to 36% of organisms detected in the system are used to document the distribution of pathways in coexisting organisms. Consistent with prior findings indicating metabolic handoffs in simple consortia, we find that few organisms within the community can conduct multiple sequential redox transformations. As environmental conditions change, different assemblages of organisms are selected for, altering linkages among the major biogeochemical cycles. PMID:27774985

  4. Multi-Level Contact Oxidation Process Performance When Treating Automobile Painting Wastewater: Pollutant Removal Efficiency and Microbial Community Structures

    Directory of Open Access Journals (Sweden)

    Yufang Zhu

    2017-11-01

    Full Text Available This study applied a multi-level contact oxidation process system in a pilot-scale experiment to treat automobile painting wastewater. The experimental wastewater had been pre-treated through a series of physicochemical methods, but the water still contained a high concentration of chemical oxygen demand (COD and had poor biodegradability. After the biological treatment, the COD concentration of effluent could stay below 300 mg/L. The study analyzed the effects of hydraulic residence time (HRT on COD, ammonia nitrogen (NH4+-N, and total nitrogen (TN. The optimal HRT was 8 h; at that time, removal efficiencies of COD, ammonia nitrogen, and total nitrogen were 83.8%, 86.3%, and 65%, respectively. The system also greatly reduced excess sludge production; the removal efficiency was 82.8% with a HRT of 8 h. The study applied high-throughput pyrosequencing technology to evaluate the microbial diversity and community structures in distinct stages of the biological reactor. The relevance between process performance and microbial community structure was analyzed at the phylum and class level. The abundant Firmicutes made a large contribution to improving the biodegradability of painting wastewater through hydrolysis acidification and reducing sludge production through fermentation in the biological reactor.

  5. Green Process Innovation and Innovation Benefit: The Mediating Effect of Firm Image

    Directory of Open Access Journals (Sweden)

    Yuan Ma

    2017-09-01

    Full Text Available By evaluating green process innovation and its innovator’s benefit including short- and long-term dimensions, we first analyzed the relationship between green process innovation and its benefits. Second, we set up a regression model to test the hypotheses using 267 survey data from coal mining firms in China. Finally, we verified the positive relationship between green process innovation and its long-term benefit, and the non-significant relationship between green process innovation and its short-term benefit, and the mediating effect played by firm image in the long run.

  6. Allopurinol-mediated lignocellulose-derived microbial inhibitor tolerance by Clostridium beijerinckii during acetone-butanol-ethanol (ABE) fermentation.

    Science.gov (United States)

    Ujor, Victor; Agu, Chidozie Victor; Gopalan, Venkat; Ezeji, Thaddeus Chukwuemeka

    2015-04-01

    In addition to glucans, xylans, and arabinans, lignocellulosic biomass hydrolysates contain significant levels of nonsugar components that are toxic to the microbes that are typically used to convert biomass to biofuels and chemicals. To enhance the tolerance of acetone-butanol-ethanol (ABE)-generating Clostridium beijerinckii NCIMB 8052 to these lignocellulose-derived microbial inhibitory compounds (LDMICs; e.g., furfural), we have been examining different metabolic perturbation strategies to increase the cellular reductant pools and thereby facilitate detoxification of LDMICs. As part of these efforts, we evaluated the effect of allopurinol, an inhibitor of NAD(P)H-generating xanthine dehydrogenase (XDH), on C. beijerinckii grown in furfural-supplemented medium and found that it unexpectedly increased the rate of detoxification of furfural by 1.4-fold and promoted growth, butanol, and ABE production by 1.2-, 2.5-, and 2-fold, respectively. Since NAD(P)H/NAD(P)(+) levels in C. beijerinckii were largely unchanged upon allopurinol treatment, we postulated and validated a possible basis in DNA repair to account for the solventogenic gains with allopurinol. Following the observation that supplementation of allopurinol in the C. beijerinckii growth media mitigates the toxic effects of nalidixic acid, a DNA-damaging antibiotic, we found that allopurinol elicited 2.4- and 6.7-fold increase in the messenger RNA (mRNA) levels of xanthine and hypoxanthine phosphoribosyltransferases, key purine-salvage enzymes. Consistent with this finding, addition of inosine (a precursor of hypoxanthine) and xanthine led to 1.4- and 1.7-fold increase in butanol production in furfural-challenged cultures of C. beijerinckii. Taken together, our results provide a purine salvage-based rationale for the unanticipated effect of allopurinol in improving furfural tolerance of the ABE-fermenting C. beijerinckii.

  7. Effects of nitrogen deposition and cattle grazing on productivity, invasion impact, and soil microbial processes in a serpentine grassland

    Science.gov (United States)

    Pasari, J.; Hernandez, D.; Selmants, P. C.; Keck, D.

    2010-12-01

    In recent decades, human activities have vastly increased the amount of biologically available nitrogen (N) in the biosphere. The resulting increase in N availability has broadly affected ecosystems through increased productivity, changes in species composition, altered nutrient cycles, and increases in invasion by exotic plant species, especially in systems that were historically low in N. California serpentine grasslands are N-limited ecosystems historically dominated by native species including several threatened and endangered plants and animals. Cattle grazing has emerged as the primary tool for controlling the impact of nitrophilic exotic grasses whose increased abundance has paralleled the regional traffic-derived increase in atmospheric N deposition. We examined the interactive effects of cattle grazing and N deposition on plant community composition, productivity, invasion resistance, and microbial processes in the Bay Area's largest serpentine grassland to determine the efficacy of current management strategies as well as the biogeochemical consequences of exotic species invasion. In the first two years of the study, aboveground net primary productivity decreased in response to grazing and increased in response to nitrogen addition. However, contrary to our hypotheses the change in productivity was not due to an increase in exotic species cover as there was little overall effect of grazing or N addition on species composition. Microbial activity was more responsive to grazing and N. Potential net N mineralization rates increased with N addition, but were not affected by grazing. In contrast, soil respiration rates were inhibited by grazing, but were not affected by N addition; suggesting strong carbon-limitation of soil microbial activity, particularly under grazing. Site differences in soil depth and grazing intensity were often more important than treatment effects. We suspect that the unusually dry conditions in the first two growing seasons inhibited

  8. Effects of non-dissolved redox mediators on a hexavalent chromium bioreduction process

    Directory of Open Access Journals (Sweden)

    Jing Lian

    2016-03-01

    Full Text Available The effects of six non-dissolved redox mediators (RM immobilized in cellulose acetate beads on enhancing Cr(VI reduction by Mangrovibacter plantisponsor CR1 were investigated. In addition, the voltammetric behaviours and electron transfer capacities of the redox mediators were examined using electrochemical methods. Compared to the control beads, the Cr(VI bioreduction rate with 1-chloroanthraquinone cellulose acetate beads (1-CAQ/CA beads was increased up to 4.5-fold, which was mainly attributed to enhanced electron transfer by 1-CAQ. The redox mediators also improved the oxidation–reduction potential values of the Cr(VI bioreduction processes, which might assist in Cr(VI bioreduction. The role of the redox mediators was discussed based on the cyclic voltammetric characteristics (E0' of the redox mediators and the electrochemical impedance spectroscopy characteristics (Rct of the RM/CA beads. A linear correlation was found for the reaction constant k and the 1-CAQ concentration (C1-CAQ, which was k = 1.5674 C1-CAQ + 4.8506 (R2 = 0.9683. The Cr(VI bioreduction was affected by temperature, and the optimum pH for the Cr(VI bioreduction was 6.5. The results of repeated-batch operations showed that 1-CAQ/CA beads exhibited good stability and persistence. This study contributes to a better understanding of the effects of the redox mediator on Cr(VI bioreduction process and demonstrates its promising potential for environmental bioremediation applications.

  9. Hydrogen production from sugar beet juice using an integrated biohydrogen process of dark fermentation and microbial electrolysis cell.

    Science.gov (United States)

    Dhar, Bipro Ranjan; Elbeshbishy, Elsayed; Hafez, Hisham; Lee, Hyung-Sool

    2015-12-01

    An integrated dark fermentation and microbial electrochemical cell (MEC) process was evaluated for hydrogen production from sugar beet juice. Different substrate to inoculum (S/X) ratios were tested for dark fermentation, and the maximum hydrogen yield was 13% of initial COD at the S/X ratio of 2 and 4 for dark fermentation. Hydrogen yield was 12% of initial COD in the MEC using fermentation liquid end products as substrate, and butyrate only accumulated in the MEC. The overall hydrogen production from the integrated biohydrogen process was 25% of initial COD (equivalent to 6 mol H2/mol hexoseadded), and the energy recovery from sugar beet juice was 57% using the combined biohydrogen. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Polyhydroxyalkanoate synthesis by mixed microbial consortia cultured on fermented dairy manure: Effect of aeration on process rates/yields and the associated microbial ecology.

    Science.gov (United States)

    Coats, Erik R; Watson, Benjamin S; Brinkman, Cynthia K

    2016-12-01

    Polyhydroxyalkanoates (PHAs) are biodegradable polymers that can substitute for petroleum-based plastics in a variety of applications. One avenue to commercial PHA production involves coupling waste-based synthesis with the use of mixed microbial consortia (MMC). In this regard, production requires maximizing the enrichment of a MMC capable of feast-famine PHA synthesis, with the metabolic response induced through imposition of aerobic-dynamic feeding (ADF) conditions. However, the concept of PHA production in complex matrices remains unrefined; process operational improvements are needed, along with an enhanced understanding of the MMC. Research presented herein investigated the effect of aeration on feast-famine PHA synthesis, with four independent aeration state systems studied; MMC were fed volatile fatty acid (VFA)-rich fermented dairy manure. Regardless of the aeration state, all MMC exhibited a feast-famine response based on observed carbon cycling. Moreover, there was no statistical difference in PHA synthesis rates, with q PHA ranging from 0.10 to 0.19 CmmolPHA gVSS -1 min -1 ; VFA uptake rates exhibited similar statistical indifferences. PHA production assessments on the enriched MMC resulted in maximum intracellular concentrations ranging from 22.5 to 90.7% (mgPHA mgVSS -1 ); at maximum concentration, the mean hydroxyvalerate mol content was 73 ± 0.6%. While a typical feast-famine dissolved oxygen (DO) pattern was observed at maximum aeration, less resolution was observed at decreasing aeration rates, suggesting that DO may not be an optimal process monitoring parameter. At lower aeration states, nitrogen cycling patterns, supported by molecular investigations targeting AOBs and NOBs, indicate that NO 2 and NO 3 sustained feast-famine PHA synthesis. Next-generation sequencing analysis of the respective MMC revealed numerous and diverse genera exhibiting the potential to achieve PHA synthesis, suggesting functional redundancy embedded in the diverse

  11. Bioelectricity Generation and Bioremediation of an Azo-Dye in a Microbial Fuel Cell Coupled Activated Sludge Process

    Science.gov (United States)

    Khan, Mohammad Danish; Abdulateif, Huda; Ismail, Iqbal M.; Sabir, Suhail; Khan, Mohammad Zain

    2015-01-01

    Simultaneous bioelectricity generation and dye degradation was achieved in the present study by using a combined anaerobic-aerobic process. The anaerobic system was a typical single chambered microbial fuel cell (SMFC) which utilizes acid navy blue r (ANB) dye along with glucose as growth substrate to generate electricity. Four different concentrations of ANB (50, 100, 200 and 400 ppm) were tested in the SMFC and the degradation products were further treated in an activated sludge post treatment process. The dye decolorization followed pseudo first order kinetics while the negative values of the thermodynamic parameter ∆G (change in Gibbs free energy) shows that the reaction proceeds with a net decrease in the free energy of the system. The coulombic efficiency (CE) and power density (PD) attained peak values at 10.36% and 2,236 mW/m2 respectively for 200 ppm of ANB. A further increase in ANB concentrations results in lowering of cell potential (and PD) values owing to microbial inhibition at higher concentrations of toxic substrates. Cyclic voltammetry studies revealed a perfect redox reaction was taking place in the SMFC. The pH, temperature and conductivity remain 7.5–8.0, 27(±2°C and 10.6–18.2 mS/cm throughout the operation. The biodegradation pathway was studied by the gas chromatography coupled with mass spectroscopy technique, suggested the preferential cleavage of the azo bond as the initial step resulting in to aromatic amines. Thus, a combined anaerobic-aerobic process using SMFC coupled with activated sludge process can be a viable option for effective degradation of complex dye substrates along with energy (bioelectricity) recovery. PMID:26496083

  12. Microbial community and treatment ability investigation in AOAO process for the optoelectronic wastewater treatment using PCR-DGGE biotechnology.

    Science.gov (United States)

    Chen, Hsi-Jien; Lin, Yi-Zi; Fanjiang, Jen-Mao; Fan, Chihhao

    2013-04-01

    This study aimed to explore the microbial community variation and treatment ability of a full-scale anoxic-aerobic-anoxic-aerobic (AOAO) process used for optoelectronic wastewater treatment. The sludge samples in the biological treatment units were collected and subsequently subjected to polymerase chain reaction (PCR) amplification and denaturing gradient gel electrophoresis identification and the wastewater components such as BOD5 and NH3-N were evaluated during the processes. The group specific primers selected were targeting at the kingdom Bacteria, the Acidobacterium, the α-proteobacteria, the β-proteobacteria ammonia oxidizers, Actinobacteria and methyllotrophs, and the 16S rDNA clone libraries were established. Ten different clones were obtained using the Bacteria primers and eight different clones were obtained using the β-proteobacteria ammonia oxidizer primers. Over 95 % of BOD5 and 90 % of NH3-N were removed from the system. The microbial community analysis showed that the Janthinobacterium sp. An8 and Nitrosospira sp. were the dominant species throughout the AOAO process. Across the whole clone library, six clones showed closely related to Janthinobacterium sp. and these species seemed to be the dominant species with more than 50 % occupancy of the total population. Nitrosospira sp. was the predominant species within the β-proteobacteria and occupied more than 30 % of the total population in the system. These two strains were the novel species specific to the AOAO process for optoelectronic treatment, and they were found strongly related to the system capability of removing aquatic contaminants by inspecting the wastewater concentration variation across the system.

  13. Influence of Silver nanoparticles on nutrient removal and microbial communities in SBR process after long-term exposure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhaohan [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No73, Huanghe Road, Nangang District, Harbin 150090 (China); Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, No 43, Songfa Street, Daoli District, Harbin 150001 (China); Gao, Peng, E-mail: hitzzh@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No73, Huanghe Road, Nangang District, Harbin 150090 (China); Li, Moqing; Cheng, Jiaqi [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No73, Huanghe Road, Nangang District, Harbin 150090 (China); Liu, Wei [Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, No 43, Songfa Street, Daoli District, Harbin 150001 (China); Feng, Yujie, E-mail: yujief@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No73, Huanghe Road, Nangang District, Harbin 150090 (China)

    2016-11-01

    The widespread utilization of silver nanoparticles (AgNPs) in industrial and commercial products inevitably raises the release into wastewater that might cause potential negative impacts on sewage treatment system. In this paper, long-term exposure experiments at four levels were conducted to determine whether AgNPs caused adverse impacts on nutrient removals in sequencing batch reactors (SBRs) and changes of microbial community structure. Compared with the control reactor (without AgNPs), carbon, nitrogen and phosphorus removal in presence of 0.1 mg/L AgNPs was no difference. However, presence of 1.0 and 10 mg/L AgNPs decreased the average removal efficiencies of COD from 95.4% to 85.2% and 68.3%, ammonia nitrogen from 98.8% to 71.2% and 49%, SOP from 97.6% to 75.5% and 54.1%, respectively. It was found that AgNPs could accumulate in sludge with the distribution coefficients of 39.2–114 L/g, inhibit the protein and polysaccharide production in EPS, reduce the SOUR of sludge, and greatly increase LDH release from microbial cells. The illumina high-throughput sequencing results indicated that AgNPs concentration changed the structures of bacterial communities, associating with the effects of AgNPs on reactor performance. Sequence analyses showed that Proteobacteria, Bacteroidetes and Acidobacteria were the dominant phyla. It was notable that AgNPs addition reduced the contents of several nitrifying bacteria at genera level in sludge, leading to the lower removal of nitrogen. - Highlights: • More than 1.0 mg/L AgNPs evidently reduce COD, NH{sub 4}{sup +}-N and SOP removal in SBR process. • AgNPs decrease the protein and polysaccharide contents of EPS. • AgNPs increase LDH release for 1.46–2.41 times. • AgNPs are apt to accumulate on surface and even into microbial cells. • AgNPs levels affect microbial community structure and composition.

  14. Influence of Silver nanoparticles on nutrient removal and microbial communities in SBR process after long-term exposure

    International Nuclear Information System (INIS)

    Zhang, Zhaohan; Gao, Peng; Li, Moqing; Cheng, Jiaqi; Liu, Wei; Feng, Yujie

    2016-01-01

    The widespread utilization of silver nanoparticles (AgNPs) in industrial and commercial products inevitably raises the release into wastewater that might cause potential negative impacts on sewage treatment system. In this paper, long-term exposure experiments at four levels were conducted to determine whether AgNPs caused adverse impacts on nutrient removals in sequencing batch reactors (SBRs) and changes of microbial community structure. Compared with the control reactor (without AgNPs), carbon, nitrogen and phosphorus removal in presence of 0.1 mg/L AgNPs was no difference. However, presence of 1.0 and 10 mg/L AgNPs decreased the average removal efficiencies of COD from 95.4% to 85.2% and 68.3%, ammonia nitrogen from 98.8% to 71.2% and 49%, SOP from 97.6% to 75.5% and 54.1%, respectively. It was found that AgNPs could accumulate in sludge with the distribution coefficients of 39.2–114 L/g, inhibit the protein and polysaccharide production in EPS, reduce the SOUR of sludge, and greatly increase LDH release from microbial cells. The illumina high-throughput sequencing results indicated that AgNPs concentration changed the structures of bacterial communities, associating with the effects of AgNPs on reactor performance. Sequence analyses showed that Proteobacteria, Bacteroidetes and Acidobacteria were the dominant phyla. It was notable that AgNPs addition reduced the contents of several nitrifying bacteria at genera level in sludge, leading to the lower removal of nitrogen. - Highlights: • More than 1.0 mg/L AgNPs evidently reduce COD, NH_4"+-N and SOP removal in SBR process. • AgNPs decrease the protein and polysaccharide contents of EPS. • AgNPs increase LDH release for 1.46–2.41 times. • AgNPs are apt to accumulate on surface and even into microbial cells. • AgNPs levels affect microbial community structure and composition.

  15. Biodegradation of isopropanol and acetone under denitrifying conditions by Thauera sp. TK001 for nitrate-mediated microbially enhanced oil recovery.

    Science.gov (United States)

    Fida, Tekle Tafese; Gassara, Fatma; Voordouw, Gerrit

    2017-07-15

    Amendment of reservoir fluid with injected substrates can enhance the growth and activity of microbes. The present study used isopropyl alcohol (IPA) or acetone to enhance the indigenous anaerobic nitrate-reducing bacterium Thauera sp. TK001. The strain was able to grow on IPA or acetone and nitrate. To monitor effects of strain TK001 on oil recovery, sand-packed columns containing heavy oil were flooded with minimal medium at atmospheric or high (400psi) pressure. Bioreactors were then inoculated with 0.5 pore volume (PV) of minimal medium containing Thauera sp. TK001 with 25mM of acetone or 22.2mM of IPA with or without 80mM nitrate. Incubation without flow for two weeks and subsequent injection with minimal medium gave an additional 17.0±6.7% of residual oil in place (ROIP) from low-pressure bioreactors and an additional 18.3% of ROIP from the high-pressure bioreactors. These results indicate that acetone or IPA, which are commonly used organic solvents, are good substrates for nitrate-mediated microbial enhanced oil recovery (MEOR), comparable to glucose, acetate or molasses, tested previously. This technology may be used for coupling biodegradation of IPA and/or acetone in waste streams to MEOR where these waste streams are generated in close proximity to an oil field. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Dynamics of microbial community during the extremely long-term fermentation process of a traditional soy sauce.

    Science.gov (United States)

    Yang, Yang; Deng, Yue; Jin, Yulan; Liu, Yanxi; Xia, Baixue; Sun, Qun

    2017-08-01

    Soy sauce produced by long-term natural fermentation is a traditional specialty in Asia, with a reputation for superior quality and rich flavour. In this study, both culture-dependent and culture-independent approaches were used to investigate the microbial diversity and community dynamics during an extremely long-term (up to 4 years) natural fermentation of Xianshi Soy Sauce, a national intangible cultural heritage. Genera of Bacillus, Aspergillus and Cladosporium were detected by both methods above. The relative abundance of the genera Bacillus and Weissella was significantly higher in the late stage than in the early one, while the genera Klebsiella and Shimwellia were opposite (P fermentation time, while there was a fair homogeneousness among samples of the same year, especially during the late fermentation stage. The clustering analysis tended to separate the fermented mashes of the 4th year from the earlier stages, suggesting the necessity of the long fermentation period for developing distinctive microbiota and characteristic quality-related compounds. This is the first report to explore the temporal changes in microbial dynamics over a period of 4 years in traditional fermentation of soy sauce, and this work illustrated the importance of isolation of appropriate strains to be used as starter cultures in brewing processes. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  17. Microbial process for the preparation of acetic acid as well as solvent for its extraction from the fermentation broth

    Science.gov (United States)

    Gaddy, James L.; Clausen, Edgar C.; Ko, Ching-Whan; Wade, Leslie E.; Wikstrom, Carl V.

    2002-01-01

    A modified water-immiscible solvent useful in the extraction of acetic acid from aqueous streams is a substantially pure mixture of isomers of highly branched di-alkyl amines. This solvent is substantially devoid of mono-alkyl amines and alcohols. Solvent mixtures formed of such a modified solvent with a desired cosolvent, preferably a low boiling hydrocarbon which forms an azeotrope with water are useful in the extraction of acetic acid from aqueous gaseous streams. An anaerobic microbial fermentation process for the production of acetic acid employs such solvents, under conditions which limit amide formation by the solvent and thus increase the efficiency of acetic acid recovery. Methods for the direct extraction of acetic acid and the extractive fermentation of acetic acid also employ the modified solvents and increase efficiency of acetic acid production. Such increases in efficiency are also obtained where the energy source for the microbial fermentation contains carbon dioxide and the method includes a carbon dioxide stripping step prior to extraction of acetic acid in solvent.

  18. A novel process-based model of microbial growth: self-inhibition in Saccharomyces cerevisiae aerobic fed-batch cultures.

    Science.gov (United States)

    Mazzoleni, Stefano; Landi, Carmine; Cartenì, Fabrizio; de Alteriis, Elisabetta; Giannino, Francesco; Paciello, Lucia; Parascandola, Palma

    2015-07-30

    Microbial population dynamics in bioreactors depend on both nutrients availability and changes in the growth environment. Research is still ongoing on the optimization of bioreactor yields focusing on the increase of the maximum achievable cell density. A new process-based model is proposed to describe the aerobic growth of Saccharomyces cerevisiae cultured on glucose as carbon and energy source. The model considers the main metabolic routes of glucose assimilation (fermentation to ethanol and respiration) and the occurrence of inhibition due to the accumulation of both ethanol and other self-produced toxic compounds in the medium. Model simulations reproduced data from classic and new experiments of yeast growth in batch and fed-batch cultures. Model and experimental results showed that the growth decline observed in prolonged fed-batch cultures had to be ascribed to self-produced inhibitory compounds other than ethanol. The presented results clarify the dynamics of microbial growth under different feeding conditions and highlight the relevance of the negative feedback by self-produced inhibitory compounds on the maximum cell densities achieved in a bioreactor.

  19. Self-centeredness and selflessness: happiness correlates and mediating psychological processes.

    Science.gov (United States)

    Dambrun, Michael

    2017-01-01

    The main objective of this research was to test central assumptions from the Self-centeredness/Selflessness Happiness Model. According to this model, while self-centered psychological functioning induces fluctuating happiness, authentic-durable happiness results from selflessness. Distinct mediating processes are supposed to account for these relationships: afflictive affects (e.g., anger, fear, jealousy, frustration) in the case of the former, and both emotional stability and feelings of harmony in the case of the latter. We tested these hypotheses in two studies based on heterogeneous samples of citizens ( n  = 547). Factor analyses revealed that self-centeredness (assessed through egocentrism and materialism) and selflessness (assessed through self-transcendence and connectedness to other) were two distinct psychological constructs. Second, while self-centeredness was positively and significantly related to fluctuating happiness, selflessness was positively and significantly related to authentic-durable happiness. Finally, distinct psychological processes mediated these relationships (study 2). On one hand, the relationship between self-centeredness and fluctuating happiness was fully mediated by afflictive affects. On the other hand, emotional stability and the feeling of being in harmony partially mediated the relation between selflessness and authentic-durable happiness.

  20. Self-centeredness and selflessness: happiness correlates and mediating psychological processes

    Science.gov (United States)

    2017-01-01

    The main objective of this research was to test central assumptions from the Self-centeredness/Selflessness Happiness Model. According to this model, while self-centered psychological functioning induces fluctuating happiness, authentic–durable happiness results from selflessness. Distinct mediating processes are supposed to account for these relationships: afflictive affects (e.g., anger, fear, jealousy, frustration) in the case of the former, and both emotional stability and feelings of harmony in the case of the latter. We tested these hypotheses in two studies based on heterogeneous samples of citizens (n = 547). Factor analyses revealed that self-centeredness (assessed through egocentrism and materialism) and selflessness (assessed through self-transcendence and connectedness to other) were two distinct psychological constructs. Second, while self-centeredness was positively and significantly related to fluctuating happiness, selflessness was positively and significantly related to authentic–durable happiness. Finally, distinct psychological processes mediated these relationships (study 2). On one hand, the relationship between self-centeredness and fluctuating happiness was fully mediated by afflictive affects. On the other hand, emotional stability and the feeling of being in harmony partially mediated the relation between selflessness and authentic–durable happiness. PMID:28507820

  1. Polarization control of intermediate state absorption in resonance-mediated multi-photon absorption process

    International Nuclear Information System (INIS)

    Xu, Shuwu; Yao, Yunhua; Jia, Tianqing; Ding, Jingxin; Zhang, Shian; Sun, Zhenrong; Huang, Yunxia

    2015-01-01

    We theoretically and experimentally demonstrate the control of the intermediate state absorption in an (n + m) resonance-mediated multi-photon absorption process by the polarization-modulated femtosecond laser pulse. An analytical solution of the intermediate state absorption in a resonance-mediated multi-photon absorption process is obtained based on the time-dependent perturbation theory. Our theoretical results show that the control efficiency of the intermediate state absorption by the polarization modulation is independent of the laser intensity when the transition from the intermediate state to the final state is coupled by the single-photon absorption, but will be affected by the laser intensity when this transition is coupled by the non-resonant multi-photon absorption. These theoretical results are experimentally confirmed via a two-photon fluorescence control in (2 + 1) resonance-mediated three-photon absorption of Coumarin 480 dye and a single-photon fluorescence control in (1 + 2) resonance-mediated three-photon absorption of IR 125 dye. (paper)

  2. Beyond cognitive framing processes: anger mediates the effects of responsibility framing on the preference for punitive measures

    NARCIS (Netherlands)

    Kühne, R.J.; Weber, P.; Sommer, K.

    2015-01-01

    A new stream of research indicates that framing effects are based on emotional as well as cognitive processes. However, it is not entirely clear whether emotions mediate framing effects and what the moderators of emotional mediation processes are. To address these questions, we conducted an

  3. Exploring Microbial Processes with Thermal-Hydrological Models of the Eastern Flank of the Juan de Fuca Ridge

    Science.gov (United States)

    Weathers, T. S.; Fisher, A. T.; Winslow, D. M.; Stauffer, P. H.; Gable, C. W.

    2017-12-01

    The flanks of mid-ocean ridges experience coupled flows of fluid, heat, and solutes that are critical for a wide range of global processes, including the cycling of carbon and nutrients, which supports a vast crustal biosphere. Only a few ridge-flank sites have been studied in detail; hydrogeologic conditions and processes in the volcanic crust are best understood on the eastern flank of the Juan de Fuca Ridge. This area has been extensively explored with decades of drilling, submersible, observatory, and survey expeditions and experiments, including the first hole-to-hole tracer injection experiment in the ocean crust. This study describes the development of reactive transport simulations for this ridge-flank setting using three-dimensional coupled (thermal-hydrological) models of crustal-scale circulation, beginning with the exploration of tracer transport. The prevailing flow direction is roughly south to north as a result of outcrop-to-outcrop flow, with a bulk flow rate in the range of meters/year. However, tracer was detected 500 m south ("upstream") from the injection borehole during the first year following injection. This may be explained by local mixing and/or formation fluid discharge from the southern borehole during and after injection. The constraints and parameters required to fit the observed tracer behavior can be used as a basis for modeling reactive transport processes such as nutrient delivery or microbial community evolution as a function of fluid flow. For example, the sulfate concentration in fluid samples from Baby Bare outcrop ( 8 km south of the tracer transport experiment) was 17.8 mmol/kg, whereas at Mama Bare outcrop ( 8 km to north of the tracer transport experiment) the sulfate concentration was 16.3 mmol/mg. By integrating laboratory-derived sulfate reduction rates from microbial samples originating from Juan de Fuca borehole observatories into reactive transport models, we can explore the range of microbial activity that supports

  4. Using cooperatives ontologies for the customization of hybrid mediator interrogation process

    Directory of Open Access Journals (Sweden)

    Cherrat LOUBNA

    2011-06-01

    Full Text Available The explosion of information sources accessible via the Web created the need for mediation tools between users and heterogeneous information sources on the Web. However, the interface design of these mediators, with taking into account the wide variety of skills and knowledge of users, and the need for them to share their preferences, requires systems able to guide the user through the interrogation process. In this paper, we try to raise this challenge  by proposing, on one hand, the use of a cooperative ontology’s models, which adapt with the evolution of user’s profiles and the dynamic change of integrated sources, and secondly ensure sharing the knowledge between users which will facilitate analysis of information and improve the data quality research process in space  and time.

  5. The psychological aftermath of bereavement : Risk factors, mediating processes, and intervention

    OpenAIRE

    Van der Houwen, H.K.

    2009-01-01

    In this dissertation some of the major facets associated with the psychological effects of bereavement were the subject of investigation: risk factors, mediating processes and intervention. Previous research on risk factors is limited because of a number of methodological shortcomings: a focus on only one or a few factors (which increases the chances of reporting spurious results) and reliance on use of a single measure of bereavement outcome. We avoided these pitfalls by simultaneously exami...

  6. Sulfur in serpentinized oceanic peridotites: Serpentinization processes and microbial sulfate reduction

    Science.gov (United States)

    Alt, J.C.; Shanks, Wayne C.

    1998-01-01

    The mineralogy, contents, and isotopic compositions of sulfur in oceanic serpentinites reflect variations in temperatures and fluid fluxes. Serpentinization of serpentinization of Iberian Margin peridotites occurred at low temperatures (???20??-200??C) and high water/rock ratios. Complete serpentinization and consumption of ferrous iron allowed evolution to higher fO2. Microbial reduction of seawater sulfate resulted in addition of low-??34S sulfide (-15 to -43???) and formation of higher-sulfur assemblages that include valleriite and pyrite. The high SO4/total S ratio of Hess Deep serpentinites (0.89) results in an increase of total sulfur and high ??34S of total sulfur (mean ??? 8???). In contrast, Iberian Margin serpentinites gained large amounts of 34S-poor sulfide (mean total S = 3800 ppm), and the high sulfide/total S ratio (0.61) results in a net decrease in ??34S of total sulfur (mean ??? -5???). Thus serpentinization is a net sink for seawater sulfur, but the amount fixed and its isotopic composition vary significantly. Serpentinization may result in uptake of 0.4-14 ?? 1012 g S yr-1 from the oceans, comparable to isotopic exchange in mafic rocks of seafloor hydrothermal systems and approaching global fluxes of riverine sulfate input and sedimentary sulfide output.

  7. Assessment of microbial processes on gas production at radioactive low-level waste disposal sites

    International Nuclear Information System (INIS)

    Weiss, A.J.; Tate, R.L. III; Colombo, P.

    1982-05-01

    Factors controlling gaseous emanations from low level radioactive waste disposal sites are assessed. Importance of gaseous fluxes of methane, carbon dioxide, and possible hydrogen from the site, stems from the inclusion of tritium and/or carbon-14 into the elemental composition of these compounds. In that the primary source of these gases is the biodegradation of organic components of the waste material, primary emphasis of the study involved an examination of the biochemical pathways producing methane, carbon dioxide, and hydrogen, and the environmental parameters controlling the activity of the microbial community involved. Initial examination of the data indicates that the ecosystem is anaerobic. As the result of the complexity of the pathway leading to methane production, factors such as substrate availability, which limit the initial reaction in the sequence, greatly affect the overall rate of methane evolution. Biochemical transformations of methane, hydrogen and carbon dioxide as they pass through the soil profile above the trench are discussed. Results of gas studies performed at three commercial low level radioactive waste disposal sites are reviewed. Methods used to obtain trench and soil gas samples are discussed. Estimates of rates of gas production and amounts released into the atmosphere (by the GASFLOW model) are evaluated. Tritium and carbon-14 gaseous compounds have been measured in these studies; tritiated methane is the major radionuclide species in all disposal trenches studied. The concentration of methane in a typical trench increases with the age of the trench, whereas the concentration of carbon dioxide is similar in all trenches

  8. The chemical properties and microbial community characterization of the thermophilic microaerobic pretreatment process.

    Science.gov (United States)

    Fu, Shan-Fei; He, Shuai; Shi, Xiao-Shuang; Katukuri, Naveen Reddy; Dai, Meng; Guo, Rong-Bo

    2015-12-01

    Thermophilic microaerobic pretreatment (TMP) was recently reported as an efficient pretreatment method of anaerobic digestion (AD). In this study, the chemical properties and microbial community were characterized to reveal how TMP working. Compared with thermophilic treatment under anaerobic condition (TMP0), cellulase activity obviously improved under microaerobic condition (TMP1), which was 10.9-49.0% higher than that of TMP0. Reducing sugar, SCOD and VFAs concentrations of TMP1 were 2.6-8.9%, 1.8-4.8% and 13.8-24% higher than those of TMP0, respectively. TMP gave obvious rise to phylum Firmicutes, which associated with extracellular enzymes production. The proportion of class Bacilli (belongs to phylum Firmicutes and mainly acts during hydrolysis) in TMP1 was 124.89% higher than that of TMP0, which reflected the greater hydrolytic ability under microaerobic condition. The improved abundance of phylum Firmicutes (especially class Bacilli, order Bacillales) under microaerobic condition could be the fundamental reason for the improved AD performance of thermophilic microaerobic pretreated corn straw. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. An overview of field specific designs of microbial EOR

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, E.P.; Bala, G.A.; Fox, S.L.; Jackson, J.D.; Thomas, C.P.

    1995-12-01

    The selection and design of a microbial enhanced oil recovery (MEOR) process for application in a specific field involves geological, reservoir, and biological characterization. Microbially mediated oil recovery mechanisms (biogenic gas, biopolymers, and biosurfactants) are defined by the types of microorganisms used. The engineering and biological character of a given reservoir must be understood to correctly select a microbial system to enhance oil recovery. The objective of this paper is to discuss the methods used to evaluate three fields with distinct characteristics and production problems for the applicability of MEOR technology. Reservoir characteristics and laboratory results indicated that MEOR would not be applicable in two of the three fields considered. The development of a microbial oil recovery process for the third field appeared promising. Development of a bacterial consortium capable of producing the desired metabolites was initiated and field isolates were characterized.

  10. Energy-neutral sustainable nutrient recovery incorporated with the wastewater purification process in an enlarged microbial nutrient recovery cell

    Science.gov (United States)

    Sun, Dongya; Gao, Yifan; Hou, Dianxun; Zuo, Kuichang; Chen, Xi; Liang, Peng; Zhang, Xiaoyuan; Ren, Zhiyong Jason; Huang, Xia

    2018-04-01

    Recovery of nutrient resources from the wastewater is now an inevitable strategy to maintain the supply of both nutrient and water for our huge population. While the intensive energy consumption in conventional nutrient recovery technologies still remained as the bottleneck towards the sustainable nutrient recycle. This study proposed an enlarged microbial nutrient recovery cell (EMNRC) which was powered by the energy contained in wastewater and achieved multi-cycle nutrient recovery incorporated with in situ wastewater treatment. With the optimal recovery solution of 3 g/L NaCl and the optimal volume ratio of wastewater to recovery solution of 10:1, >89% of phosphorus and >62% of ammonium nitrogen were recovered into struvite. An extremely low water input ratio of water. It was proved the EMNRC system was a promising technology which could utilize the chemical energy contained in wastewater itself and energy-neutrally recover nutrient during the continuous wastewater purification process.

  11. Effect of Temperature on Precipitation Rate of Calcium Carbonate Produced through Microbial Metabolic Process of Bio Materials

    Directory of Open Access Journals (Sweden)

    Prima Yane Putri

    2016-09-01

    Full Text Available Concrete is the most widely used construction material in civil engineering. But plain concrete is a brittle material and has little resistance to cracking. The cracking in concrete promotes deterioration such as the corrosion of reinforcing rebar, therefore, repair in filling the crack is often carried out. Recently, repair methods using bio-based materials associated with microbial metabolic processes leading to precipitation of calcium carbonate have been intensively studied. In this study, influencing factors on the precipitation rate depending on the constituents of bio-based material comprising yeast, glucose and calcium acetate mixed in tris buffer solution was examined for improving the rate of initial reactions. In addition, effect of temperature change on the amount of calcium carbonate precipitation was also investigated. The precipitates were identified by X-ray diffraction. It was shown that the increase of temperature lead to a change on calcium carbonate precipitation and caused the pH decrease under 7.0.

  12. Flavor changing processes in supersymmetric models with hybrid gauge- and gravity-mediation

    International Nuclear Information System (INIS)

    Hiller, Gudrun; Hochberg, Yonit; Nir, Yosef

    2009-01-01

    We consider supersymmetric models where gauge mediation provides the dominant contributions to the soft supersymmetry breaking terms while gravity mediation provides sub-dominant yet non-negligible contributions. We further assume that the gravity-mediated contributions are subject to selection rules that follow from a Froggatt-Nielsen symmetry. This class of models constitutes an example of viable and natural non-minimally flavor violating models. The constraints from K 0 -K-bar 0 mixing imply that the modifications to the Standard Model predictions for B d -B-bar d and B s - B-bar s mixing are generically at most at the percent level, but can be of order ten percent for large tan β. The modifications for D 0 -D-bar 0 mixing are generically at most of order a few percent, but in a special subclass of models they can be of order one. We point out ΔB = 1 processes relevant for flavor violation in hybrid mediation.

  13. GeoChip-based analysis of the microbial community functional structures in simultaneous desulfurization and denitrification process.

    Science.gov (United States)

    Yu, Hao; Chen, Chuan; Ma, Jincai; Liu, Wenzong; Zhou, Jizhong; Lee, Duu-Jong; Ren, Nanqi; Wang, Aijie

    2014-07-01

    The elemental sulfur (S°) recovery was evaluated in the presence of nitrate in two development models of simultaneous desulfurization and denitrification (SDD) process. At the loading rates of 0.9 kg S/(m³·day) for sulfide and 0.4 kg N/(m³·day) for nitrate, S° conversion rate was 91.1% in denitrifying sulfide removal (DSR) model which was higher than in integrated simultaneous desulfurization and denitrification (ISDD) model (25.6%). A comprehensive analysis of functional diversity, structure and metabolic potential of microbial communities was examined in two models by using functional gene array (GeoChip 2.0). GeoChip data indicated that diversity indices, community structure, and abundance of functional genes were distinct between two models. Diversity indices (Simpson's diversity index (1/D) and Shannon-Weaver index (H')) of all detected genes showed that with elevated influent loading rate, the functional diversity decreased in ISDD model but increased in DSR model. In contrast to ISDD model, the overall abundance of dsr genes was lower in DSR model, while some functional genes targeting from nitrate-reducing sulfide-oxidizing bacteria (NR-SOB), such as Thiobacillus denitrificans, Sulfurimonas denitrificans, and Paracoccus pantotrophus were more abundant in DSR model which were highly associated with the change of S(0) conversion rate obtained in two models. The results obtained in this study provide additional insights into the microbial metabolic mechanisms involved in ISDD and DSR models, which in turn will improve the overall performance of SDD process. Copyright © 2014. Published by Elsevier B.V.

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

    Science.gov (United States)

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

    2015-02-01

    A directed differentiation between the biofilm and suspension was observed in the molecular microbial ecology and gene expression of different bacteria in a biofilm nitritation-anammox process operated at varying hydraulic residence times (HRT) and nitrogen loading rates (NLR). The highest degree of enrichment observed in the biofilm was of anaerobic ammonia-oxidizing bacteria (AMX) followed by that of Nitrospira spp. related nitrite-oxidizing bacteria (NOB). For AMX, a major shift from Candidatus "Brocadia fulgida" to Candidatus "Kuenenia stuttgartiensis" in both suspension and biofilm was observed with progressively shorter HRT, using discriminatory biomarkers targeting the hydrazine synthase (hzsA) gene. In parallel, expression of the hydrazine oxidoreductase gene (hzo), a functional biomarker for AMX energy metabolism, became progressively prominent in the biofilm. A marginal but statistically significant enrichment in the biofilm was observed for Nitrosomonas europaea related ammonia-oxidizing bacteria (AOB). In direct contrast to AMX, the gene expression of ammonia monooxygenase subunit A (amoA), a functional biomarker for AOB energy metabolism, progressively increased in suspension. Using gene expression and biomass concentration measures in conjunction, it was determined that signatures of AOB metabolism were primarily present in the biofilm throughout the study. On the other hand, AMX metabolism gradually shifted from being uniformly distributed in both the biofilm and suspension to primarily the biofilm at shorter HRTs and higher NLRs. These results therefore highlight the complexity and key differences in the microbial ecology, gene expression and activity between the biofilm and suspension of a nitritation-anammox process and the biokinetic and metabolic drivers for such niche segregation. © 2014 Wiley Periodicals, Inc.

  15. 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 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.

  16. Eicosanoid-mediated immunity in insects

    Science.gov (United States)

    Eicosanoid is a collective term for oxygenated metabolites of C20 polyunsaturated fatty acids. As seen in mammals, eicosanoids play crucial roles in mediating various physiological processes, including immune responses, in insects. Upon microbial pathogen infection, non-self recognition signals are ...

  17. Sensitivity of Deep Soil Organic Carbon Age to Sorption, Transport and Microbial Interactions - Insights from a Calibrated Process Model

    Science.gov (United States)

    Ahrens, B.; Schrumpf, M.; Reichstein, M.

    2013-12-01

    Subsoil soil organic carbon (SOC) is characterized by conventional radiocarbon ages on the order of centuries to millennia. Most vertically explicit SOC turnover models represent this persistence of deep SOC by one pool that has millennial turnover times. This approach lumps different stabilizing mechanisms such as chemical recalcitrance, sorptive stabilization and energy limitation into a single rate constant. As an alternative, we present a continuous, vertically explicit SOC decomposition model that allows for stabilization via sorption and microbial interactions (COMISSION model). We compare the COMISSION model with the SOC profile of a Haplic Podzol under a Norway spruce forest. In the COMISSION model two pools receive aboveground litter input and vertically distributed root litter input. The readily leachable and soluble fraction of litter input enters a dissolved organic carbon pool (DOC), while the rest enters the residue pool which represents polymeric, non-soluble SOC. The residue pool is depolymerized with extracellular enzymes produced by a microbial pool to enter the DOC pool which represents SOC potentially available for assimilation by microbes. The adsorption/desorption of DOC from/to mineral surfaces controls the availability of carbon in the DOC pool for assimilatory uptake by microbes. The sorption of DOC is modeled with dynamic Langmuir equations. The desorbed part of the DOC pool not only constitutes the substrate for the microbial pool, but is also transported via advection. Interactions of microbes with the residue and DOC pool are modeled with Michaelis-Menten kinetics - this not only allows representing ';priming', but also the retardation of decomposition via energy limitation in the deep soil where substrate is scarce. Further, soil organic matter is recycled within the soil profile through microbial processing - dead microbes either enter the DOC or the residue pool, and thereby also contribute to longer residence times with soil depth

  18. A short overview of the microbial population in clouds: Potential roles in atmospheric chemistry and nucleation processes

    Science.gov (United States)

    Delort, Anne-Marie; Vaïtilingom, Mickael; Amato, Pierre; Sancelme, Martine; Parazols, Marius; Mailhot, Gilles; Laj, Paolo; Deguillaume, Laurent

    2010-11-01

    Recent studies showed that living microorganisms, including bacteria, fungi and yeasts, are present in the atmospheric water phase (fog and clouds) and their role in chemical processes may have been underestimated. At the interface between atmospheric science and microbiology, information about this field of science suffers from the fact that not all recent findings are efficiently conveyed to both scientific communities. The purpose of this paper is therefore to provide a short overview of recent work linked to living organisms in the atmospheric water phase, from their activation to cloud droplets and ice crystal, to their potential impact on atmospheric chemical processes. This paper is focused on the microorganisms present in clouds and on the role they could play in atmospheric chemistry and nucleation processes. First, the life cycle of microorganisms via the atmosphere is examined, including their aerosolization from sources, their integration into clouds and their wet deposition on the ground. Second, special attention is paid to the possible impacts of microorganisms on liquid and ice nucleation processes. Third, a short description of the microorganisms that have been found in clouds and their variability in numbers and diversity is presented, emphasizing some specific characteristics that could favour their occurrence in cloud droplets. In the last section, the potential role of microbial activity as an alternative route to photochemical reaction pathways in cloud chemistry is discussed.

  19. FOOD PROCESSING TECHNOLOGY AS A MEDIATOR OF FUNCTIONALITY. STRUCTURE-PROPERTY-PROCESS RELATIONSHIPS

    Directory of Open Access Journals (Sweden)

    Ester Betoret

    2015-02-01

    Full Text Available During the last years, the food industry has been facing technical and economic changes both in society and in the food processing practices, paying high attention to food products that meet the consumers´ demands. In this direction, the study areas in food process and products have evolved mainly from safety to other topics such as quality, environment or health. The improvement of the food products is now directed towards ensuring nutritional and specific functional benefits. Regarding the processes evolution, they are directed to ensure the quality and safety of environmentally friendly food products produced optimizing the use of resources, minimally affecting or even enhancing their nutritional and beneficial characteristics. The product structure both in its raw form and after processing plays an important role maintaining, enhancing and delivering the bioactive compounds in the appropriate target within the organism. The aim of this review is to make an overview on some synergistic technologies that can constitute a technological process to develop functional foods, enhancing the technological and/or nutritional functionality of the food products in which they are applied. More concretely, the effect of homogenization, vacuum impregnation and drying operations on bioactive compounds have been reviewed, focusing on the structure changes produced and its relationship on the product functionality, as well as on the parameters and the strategies used to quantify and increase the achieved functionality.

  20. Information processing speed mediates the relationship between white matter and general intelligence in schizophrenia.

    Science.gov (United States)

    Alloza, Clara; Cox, Simon R; Duff, Barbara; Semple, Scott I; Bastin, Mark E; Whalley, Heather C; Lawrie, Stephen M

    2016-08-30

    Several authors have proposed that schizophrenia is the result of impaired connectivity between specific brain regions rather than differences in local brain activity. White matter abnormalities have been suggested as the anatomical substrate for this dysconnectivity hypothesis. Information processing speed may act as a key cognitive resource facilitating higher order cognition by allowing multiple cognitive processes to be simultaneously available. However, there is a lack of established associations between these variables in schizophrenia. We hypothesised that the relationship between white matter and general intelligence would be mediated by processing speed. White matter water diffusion parameters were studied using Tract-based Spatial Statistics and computed within 46 regions-of-interest (ROI). Principal component analysis was conducted on these white matter ROI for fractional anisotropy (FA) and mean diffusivity, and on neurocognitive subtests to extract general factors of white mater structure (gFA, gMD), general intelligence (g) and processing speed (gspeed). There was a positive correlation between g and gFA (r= 0.67, p =0.001) that was partially and significantly mediated by gspeed (56.22% CI: 0.10-0.62). These findings suggest a plausible model of structure-function relations in schizophrenia, whereby white matter structure may provide a neuroanatomical substrate for general intelligence, which is partly supported by speed of information processing. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  1. Self-regulatory processes mediate the intention-behavior relation for adherence and exercise behaviors.

    Science.gov (United States)

    de Bruin, Marijn; Sheeran, Paschal; Kok, Gerjo; Hiemstra, Anneke; Prins, Jan M; Hospers, Harm J; van Breukelen, Gerard J P

    2012-11-01

    Understanding the gap between people's intentions and actual health behavior is an important issue in health psychology. Our aim in this study was to investigate whether self-regulatory processes (monitoring goal progress and responding to discrepancies) mediate the intention-behavior relation in relation to HIV medication adherence (Study 1) and intensive exercise behavior (Study 2). In Study 1, questionnaire and electronically monitored adherence data were collected at baseline and 3 months later from patients in the control arm of an HIV-adherence intervention study. In Study 2, questionnaire data was collected at 3 time points 6-weeks apart in a cohort study of physical activity. Complete data at all time points were obtained from 51 HIV-infected patients and 499 intensive exercise participants. Intentions were good predictors of behavior and explained 25 to 30% of the variance. Self-regulatory processes explained an additional 11% (Study 1) and 6% (Study 2) of variance in behavior on top of intentions. Regression and bootstrap analyses revealed at least partial, and possibly full, mediation of the intention-behavior relation by self-regulatory processes. The present studies indicate that self-regulatory processes may explain how intentions drive behavior. Future tests, using different health behaviors and experimental designs, could firmly establish whether self-regulatory processes complement current health behavior theories and should become routine targets for intervention. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

  2. Risky family processes prospectively forecast shorter telomere length mediated through negative emotions.

    Science.gov (United States)

    Brody, Gene H; Yu, Tianyi; Shalev, Idan

    2017-05-01

    This study was designed to examine prospective associations of risky family environments with subsequent levels of negative emotions and peripheral blood mononuclear cell telomere length (TL), a marker of cellular aging. A second purpose was to determine whether negative emotions mediate the hypothesized link between risky family processes and diminished telomere length. Participants were 293 adolescents (age 17 years at the first assessment) and their primary caregivers. Caregivers provided data on risky family processes when the youths were age 17 years, youths reported their negative emotions at age 18 years, and youths' TL was assayed from a blood sample at age 22 years. The results revealed that (a) risky family processes forecast heightened negative emotions (β = .316, p emotions forecast shorter TL (β = -.187, p = .012), and (c) negative emotions served as a mediator connecting risky family processes with diminished TL (indirect effect = -0.012, 95% CI [-0.036, -0.002]). These findings are consistent with the hypothesis that risky family processes presage premature cellular aging through effects on negative emotions, with potential implications for lifelong health. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  3. Mathematical Modeling of the Process for Microbial Production of Branched Chained Amino Acids

    Directory of Open Access Journals (Sweden)

    Todorov K.

    2009-12-01

    Full Text Available This article deals with modelling of branched chained amino acids production. One of important branched chained amino acid is L-valine. The aim of the article is synthesis of dynamic unstructured model of fed-batch fermentation process with intensive droppings for L-valine production. The presented approach of the investigation includes the following main procedures: description of the process by generalized stoichiometric equations; preliminary data processing and calculation of specific rates for main kinetic variables; identification of the specific rates takes into account the dissolved oxygen tension; establishment and optimisation of dynamic model of the process; simulation researches. MATLAB is used as a research environment.

  4. Trait-mediated assembly processes predict successional changes in community diversity of tropical forests.

    Science.gov (United States)

    Lasky, Jesse R; Uriarte, María; Boukili, Vanessa K; Chazdon, Robin L

    2014-04-15

    Interspecific differences in relative fitness can cause local dominance by a single species. However, stabilizing interspecific niche differences can promote local diversity. Understanding these mechanisms requires that we simultaneously quantify their effects on demography and link these effects to community dynamics. Successional forests are ideal systems for testing assembly theory because they exhibit rapid community assembly. Here, we leverage functional trait and long-term demographic data to build spatially explicit models of successional community dynamics of lowland rainforests in Costa Rica. First, we ask what the effects and relative importance of four trait-mediated community assembly processes are on tree survival, a major component of fitness. We model trait correlations with relative fitness differences that are both density-independent and -dependent in addition to trait correlations with stabilizing niche differences. Second, we ask how the relative importance of these trait-mediated processes relates to successional changes in functional diversity. Tree dynamics were more strongly influenced by trait-related interspecific variation in average survival than trait-related responses to neighbors, with wood specific gravity (WSG) positively correlated with greater survival. Our findings also suggest that competition was mediated by stabilizing niche differences associated with specific leaf area (SLA) and leaf dry matter content (LDMC). These drivers of individual-level survival were reflected in successional shifts to higher SLA and LDMC diversity but lower WSG diversity. Our study makes significant advances to identifying the links between individual tree performance, species functional traits, and mechanisms of tropical forest succession.

  5. Destruction of commercial pesticides by cerium redox couple mediated electrochemical oxidation process in continuous feed mode

    International Nuclear Information System (INIS)

    Balaji, Subramanian; Chung, Sang Joon; Ryu, Jae-Yong; Moon, Il Shik

    2009-01-01

    Mediated electrochemical oxidation was carried out for the destruction of commercial pesticide formulations using cerium(IV) in nitric acid as the mediator electrolyte solution in a bench scale set up. The mediator oxidant was regenerated in situ using an electrochemical cell. The real application of this sustainable process for toxic organic pollutant destruction lies in its ability for long term continuous operation with continuous organic feeding and oxidant regeneration with feed water removal. In this report we present the results of fully integrated MEO system. The task of operating the continuous feed MEO system for a long time was made possible by continuously removing the feed water using an evaporator set up. The rate of Ce(IV) regeneration in the electrochemical cell and the consumption for the pesticide destruction was matched based on carbon content of the pesticides. It was found that under the optimized experimental conditions for Ce(III) oxidation, organic addition and water removal destruction efficiency of ca. 99% was obtained for all pesticides studied. It was observed that the Ce(IV) concentration was maintained nearly the same throughout the experiment. The stable operation for 6 h proved that the process can be used for real applications and for possible scale up for the destruction of larger volumes of toxic organic wastes.

  6. 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

  7. Tropical forest carbon balance in a warmer world: a critical review spanning microbial- to ecosystem-scale processes

    Science.gov (United States)

    Wood, Tana E.; Cavaleri, Molly A.; Reed, Sasha C.

    2012-01-01

    Tropical forests play a major role in regulating global carbon (C) fluxes and stocks, and even small changes to C cycling in this productive biome could dramatically affect atmospheric carbon dioxide (CO2) concentrations. Temperature is expected to increase over all land surfaces in the future, yet we have a surprisingly poor understanding of how tropical forests will respond to this significant climatic change. Here we present a contemporary synthesis of the existing data and what they suggest about how tropical forests will respond to increasing temperatures. Our goals were to: (i) determine whether there is enough evidence to support the conclusion that increased temperature will affect tropical forest C balance; (ii) if there is sufficient evidence, determine what direction this effect will take; and, (iii) establish what steps should to be taken to resolve the uncertainties surrounding tropical forest responses to increasing temperatures. We approach these questions from a mass-balance perspective and therefore focus primarily on the effects of temperature on inputs and outputs of C, spanning microbial- to ecosystem-scale responses. We found that, while there is the strong potential for temperature to affect processes related to C cycling and storage in tropical forests, a notable lack of data combined with the physical, biological and chemical diversity of the forests themselves make it difficult to resolve this issue with certainty. We suggest a variety of experimental approaches that could help elucidate how tropical forests will respond to warming, including large-scale in situ manipulation experiments, longer term field experiments, the incorporation of a range of scales in the investigation of warming effects (both spatial and temporal), as well as the inclusion of a diversity of tropical forest sites. Finally, we highlight areas of tropical forest research where notably few data are available, including temperature effects on: nutrient cycling

  8. Soil environmental conditions and microbial build-up mediate the effect of plant diversity on soil nitrifying and denitrifying enzyme activities in temperate grasslands.

    Directory of Open Access Journals (Sweden)

    Xavier Le Roux

    Full Text Available Random reductions in plant diversity can affect ecosystem functioning, but it is still unclear which components of plant diversity (species number - namely richness, presence of particular plant functional groups, or particular combinations of these and associated biotic and abiotic drivers explain the observed relationships, particularly for soil processes. We assembled grassland communities including 1 to 16 plant species with a factorial separation of the effects of richness and functional group composition to analyze how plant diversity components influence soil nitrifying and denitrifying enzyme activities (NEA and DEA, respectively, the abundance of nitrifiers (bacterial and archaeal amoA gene number and denitrifiers (nirK, nirS and nosZ gene number, and key soil environmental conditions. Plant diversity effects were largely due to differences in functional group composition between communities of identical richness (number of sown species, though richness also had an effect per se. NEA was positively related to the percentage of legumes in terms of sown species number, the additional effect of richness at any given legume percentage being negative. DEA was higher in plots with legumes, decreased with increasing percentage of grasses, and increased with richness. No correlation was observed between DEA and denitrifier abundance. NEA increased with the abundance of ammonia oxidizing bacteria. The effect of richness on NEA was entirely due to the build-up of nitrifying organisms, while legume effect was partly linked to modified ammonium availability and nitrifier abundance. Richness effect on DEA was entirely due to changes in soil moisture, while the effects of legumes and grasses were partly due to modified nitrate availability, which influenced the specific activity of denitrifiers. These results suggest that plant diversity-induced changes in microbial specific activity are important for facultative activities such as denitrification

  9. Effect of high hydrostatic pressure processing on the background microbial loads and quality of cantaloupe puree.

    Science.gov (United States)

    Mukhopadhyay, Sudarsan; Sokorai, Kimberly; Ukuku, Dike; Fan, Xuetong; Juneja, Vijay

    2017-01-01

    The objective of this study was to investigate and evaluate the effects of high hydrostatic pressure (HHP) applied to cantaloupe puree (CP) on microbial loads and product quality during storage for 10days at 4°C. Freshly prepared, double sealed and double bagged CP (ca. 5g) was pressure treated at 300, 400 and 500MPa at 8°C and 15°C for 5min. Microflora populations, soluble solid content, pH, color, antioxidant activity, appearance and aroma were measured at 1, 6, and 10d of storage. Results showed that high pressure treatment of 300MPa (8°C and 15°C) resulted in reduction of total aerobic plate count from 3.3 to 1.8logCFU/g. The treatment reduced the populations of native aerobic plate count to non-detectable levels (detection limit 1logCFU/g) at 400MPa and 500MPa pressures at 15°C. Pressure treatment completely inactivated mold and yeast in puree below the limits of detection at day 1 and no regrowth was observed during 10days of storage at 4°C while mold and yeast in untreated puree survived during the storage. High pressure treatment did not show any adverse impact on physical properties as soluble solid content (SSC, 11.2°Brix) and acidity (pH, 6.9). The instrumental color parameters (L*, a*, b*) were affected due to HHP treatment creating a slightly lighter product, compared to control, as indicated by higher L.* and lower a* values. However the change was not detected by the sensory panel while evaluating appearance scores. Pressure treatment did not affect the antioxidant capacity of puree product compared to control. Visual appearance and sniffing aroma test by panel revealed no adverse changes in the sensory parameters as a result of HHP treatment. HHP method described in this study appears to be a promising way to inactivate spoilage microorganisms in the cantaloupe puree and maintain quality. This study provides a viable option for preservation and marketing this product. Published by Elsevier Ltd.

  10. Enriching distinctive microbial communities from marine sediments via an electrochemical-sulfide-oxidizing process on carbon electrodes

    Directory of Open Access Journals (Sweden)

    Shiue-Lin eLi

    2015-02-01

    Full Text Available Sulfide is a common product of marine anaerobic respiration, and a potent reactant biologically and geochemically. Here we demonstrate the impact on microbial communities with the removal of sulfide via electrochemical methods. The use of differential pulse voltammetry revealed that the oxidation of soluble sulfide was seen at + mV (vs. SHE at all pH ranges tested (from pH = 4 to 8, while non-ionized sulfide, which dominated at pH = 4 was poorly oxidized via this process. Two mixed cultures (CAT and LA were enriched from two different marine sediments (from Catalina Island, CAT; from the Port of Los Angeles, LA in serum bottles using a seawater medium supplemented with lactate, sulfate, and yeast extract, to obtain abundant biomass. Both CAT and LA cultures were inoculated in electrochemical cells (using yeast-extract-free seawater medium as an electrolyte equipped with carbon-felt electrodes. In both cases, when potentials of +630 or 130 mV (vs. SHE were applied, currents were consistently higher at +630 then at 0 mV, indicating more sulfide being oxidized at the higher potential. In addition, higher organic-acid and sulfate conversion rates were found at +630 mV with CAT, while no significant differences were found with LA at different potentials. The results of microbial-community analyses revealed a decrease in diversity for both CAT and LA after electrochemical incubation. In addition, some bacteria (e.g., Clostridium and Arcobacter not well known to be capable of extracellular electron transfer, were found to be dominant in the electrochemical cells. Thus, even though the different mixed cultures have different tolerances for sulfide, electrochemical-sulfide removal can lead to major population changes.

  11. Board members’ contribution to strategy: The mediating role of board internal processes

    Directory of Open Access Journals (Sweden)

    Carmen Barroso-Castro

    2017-05-01

    Full Text Available This study aims to explore what directors do on the board, to what extent the processes occurring in the board allow the sharing and integrating of the existing knowledge, thus facilitating the board members’ contributions to strategy. We adopt the view that the internal board processes increase the impact of the cognitive resources on board performance. Using survey data from 200 large Spanish companies we demonstrate that directors’ level of knowledge of the firm and board job-related diversity positively influence the degree of the board's strategic involvement. Additionally, the internal processes that take place within the board – particularly Cognitive Conflict, the Critical and Independent Approach and the Comprehensive Discussion Process – influence the board's strategic involvement and play a partial mediating role on the aforementioned relationships. However, our results show no evidence for a positive relationship between Board Meeting Dynamics and the board's strategic involvement.

  12. Modeling of phonon- and Coulomb-mediated capture processes in quantum dots

    DEFF Research Database (Denmark)

    Magnúsdóttir, Ingibjörg

    2003-01-01

    This thesis describes modeling of carrier relaxation processes in self-assembled quantum-dot-structures, with particular emphasis on carrier capture processes in quantum dots. Relaxation by emission of lontitudinal optical (LO) phonons is very efficient in bulk semiconductors and nanostructures...... of higher dimensionality. Here, we investigate carrier capture processes into quantum dots, mediated by emission of one and two LO phonons. In these investigations is is assumed that the dot is empty initially. In the Case of single-phonon capture we also investigate the influence of the presence...... of a charge in the quantum-dot state to which the capture takes place. In general, capture rates are of the same order as capture rates into an empty dot state, but in some cases the dot-size interval for which the capture process is energetically allowed, is considerably reduced.The above calculations...

  13. Physicochemical changes and microbial inactivation after high-intensity ultrasound processing of prebiotic whey beverage applying different ultrasonic power levels.

    Science.gov (United States)

    Guimarães, Jonas T; Silva, Eric Keven; Alvarenga, Verônica O; Costa, Ana Letícia R; Cunha, Rosiane L; Sant'Ana, Anderson S; Freitas, Monica Q; Meireles, M Angela A; Cruz, Adriano G

    2018-06-01

    In this work, we investigated the effects of the ultrasonic power (0, 200, 400 and 600 W) on non-thermal processing of an inulin-enriched whey beverage. We studied the effects of high-intensity ultrasound (HIUS) on microbial inactivation (aerobic mesophilic heterotrophic bacteria (AMHB), total and thermotolerant coliforms and yeasts and molds), zeta potential, microstructure (optical microscopy, particle size distribution), rheology, kinetic stability and color. The non-thermal processing applying 600 W of ultrasonic power was comparable to high-temperature short-time (HTST) treatment (75 °C for 15 s) concerning the inactivation of AMHB and yeasts and molds (2 vs 2 log and 0.2 vs 0.4 log, respectively), although HIUS has reached a lower output temperature (53 ± 3 °C). The HIUS was better than HTST to improve beverage kinetic stability, avoiding phase separation, which was mainly attributed to the decrease of particles size, denaturation of whey proteins and gelation of polysaccharides (inulin and gellan gum). Thus, non-thermal processing by HIUS seems to be an interesting technology for prebiotic dairy beverages production. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Microbial processes in glaciers and permafrost. A literature study on microbiology affecting groundwater at ice sheet melting

    International Nuclear Information System (INIS)

    Hallbeck, Lotta

    2009-10-01

    A repository for spent nuclear fuel will remain for hundred thousands of years. During this period, several ice ages will most likely take place. To understand the effect of melt water from ice sheets on the repository, the microbiological processes of oxygen reduction has to be elucidated. This report is a compilation of the present knowledge about biological activity in glacier environments. These environments consist of many different parts which have their own biological character depending on the prevailing physical and chemical conditions. There are, for example, ice sheets and glaciers, glacial streams and rivers, soil and water beneath the ice, soil and water in front of and beside ice sheets and glacier and deep groundwater beneath the ice. The microbiological processes of importance are consumption of oxygen by aerobic microorganisms, anaerobic organisms and their reduced metabolites, like sulphide, acetate and methane, which can act as reducing agents in biological or chemical oxygen reduction. The lithotrophic type (inorganic energy source) of metabolism is important in these cold environments. There are also microbiological processes important to radionuclide transport and the production of complexing agents, biological colloids and biofilms. The study of microbial processes in glacier and ice sheet environments is still a young scientific niche. The studies have so far mostly been concentrated to ice surfaces and the subglacial environment. The most important findings from the literature study are as follows. Primary production is ongoing in snow cover and on ice surfaces of glaciers and ice sheets. The production is dependent on the location, because of temperature and solar radiation, but also on the prevailing state of the glacier. On surfaces and in the snow cover, heterotrophic microorganisms consume oxygen and organic material. In surface ice structures anaerobic conditions may occur. The subglacial environment is very active with several types

  15. Microbial processes in glaciers and permafrost. A literature study on microbiology affecting groundwater at ice sheet melting

    Energy Technology Data Exchange (ETDEWEB)

    Hallbeck, Lotta (Microbial Analytics Sweden AB, Moelnlycke (Sweden))

    2009-10-15

    A repository for spent nuclear fuel will remain for hundred thousands of years. During this period, several ice ages will most likely take place. To understand the effect of melt water from ice sheets on the repository, the microbiological processes of oxygen reduction has to be elucidated. This report is a compilation of the present knowledge about biological activity in glacier environments. These environments consist of many different parts which have their own biological character depending on the prevailing physical and chemical conditions. There are, for example, ice sheets and glaciers, glacial streams and rivers, soil and water beneath the ice, soil and water in front of and beside ice sheets and glacier and deep groundwater beneath the ice. The microbiological processes of importance are consumption of oxygen by aerobic microorganisms, anaerobic organisms and their reduced metabolites, like sulphide, acetate and methane, which can act as reducing agents in biological or chemical oxygen reduction. The lithotrophic type (inorganic energy source) of metabolism is important in these cold environments. There are also microbiological processes important to radionuclide transport and the production of complexing agents, biological colloids and biofilms. The study of microbial processes in glacier and ice sheet environments is still a young scientific niche. The studies have so far mostly been concentrated to ice surfaces and the subglacial environment. The most important findings from the literature study are as follows. Primary production is ongoing in snow cover and on ice surfaces of glaciers and ice sheets. The production is dependent on the location, because of temperature and solar radiation, but also on the prevailing state of the glacier. On surfaces and in the snow cover, heterotrophic microorganisms consume oxygen and organic material. In surface ice structures anaerobic conditions may occur. The subglacial environment is very active with several types

  16. Neighborhood Concentrated Disadvantage and Dating Violence among Urban Adolescents: The Mediating Role of Neighborhood Social Processes.

    Science.gov (United States)

    Garthe, Rachel C; Gorman-Smith, Deborah; Gregory, Joshua; E Schoeny, Michael

    2018-03-14

    The link between relationship violence and aspects of neighborhood concentrated disadvantage (e.g., percent of unemployed adults, percent of families below poverty level), has been established. However, the literature examining neighborhood social processes, including informal social control and social cohesion, in relation to adolescent dating violence has shown mixed results with a limited theoretical foundation and methodology. Using a social disorganization theoretical framework, this study examined the mediating role of these neighborhood social processes in the relation between concentrated disadvantage and adolescent dating violence within an urban context. Participants included 605 adult residents in 30 census tracts and 203 adolescents from neighborhoods on the West and South sides of Chicago. Neighborhood-level concentrated disadvantage was measured via Census data, adult residents reported on neighborhood social processes, and youth reported on dating violence. Informal social control was negatively associated with dating violence, and social cohesion was positively associated with dating violence. A multilevel mediation model showed that concentrated disadvantage was related to higher levels of dating violence via lower levels of informal social control. These results extend social disorganization theory to dating violence within an urban context, while also highlighting the important role of neighborhood processes on relationship violence. Implications for research and intervention programming are discussed. © Society for Community Research and Action 2018.

  17. Microbial dissimilatory iron(III) reduction: Studies on the mechanism and on processes of environmental relevance

    OpenAIRE

    Jahn, Michael

    2005-01-01

    Many microbes are able to respire aerobically oxygen or anaerobically other electron acceptors for example sulphate, nitrate, manganese(IV) or Fe(III). As iron minerals are widespread in nature, dissimilatory iron(III) reduction by different microorganisms is a very important process of anaerobic respiration. The general goal of this work was to improve the knowledge of processes, in which iron-reducing microbes are said to play an important role. For this purpose, in one part the focus wa...

  18. Microbial Inoculants and Their Impact on Soil Microbial Communities: A Review

    Directory of Open Access Journals (Sweden)

    Darine Trabelsi

    2013-01-01

    Full Text Available The knowledge of the survival of inoculated fungal and bacterial strains in field and the effects of their release on the indigenous microbial communities has been of great interest since the practical use of selected natural or genetically modified microorganisms has been developed. Soil inoculation or seed bacterization may lead to changes in the structure of the indigenous microbial communities, which is important with regard to the safety of introduction of microbes into the environment. Many reports indicate that application of microbial inoculants can influence, at least temporarily, the resident microbial communities. However, the major concern remains regarding how the impact on taxonomic groups can be related to effects on functional capabilities of the soil microbial communities. These changes could be the result of direct effects resulting from trophic competitions and antagonistic/synergic interactions with the resident microbial populations, or indirect effects mediated by enhanced root growth and exudation. Combination of inoculants will not necessarily produce an additive or synergic effect, but rather a competitive process. The extent of the inoculation impact on the subsequent crops in relation to the buffering capacity of the plant-soil-biota is still not well documented and should be the focus of future research.

  19. Microbiologically mediated processes in a repository sited in a clay host rock

    International Nuclear Information System (INIS)

    Schwyn, B.; Leupin, O. X.; Bagnoud, A.; Bernier-Latmani, R.

    2012-01-01

    Document available in extended abstract form only. Because of their favourable retention properties for radionuclides, clay-rich sediments are being considered in Switzerland as host rocks for the geological disposal of high, intermediate- and low-level radioactive waste. Compacted bentonite is foreseen as backfill material in the high level waste repository whereas for intermediate- and low-level waste the near field will mainly consist of cementitious material. The evolution of both types of repositories, which includes re-saturation, heat generation (only high level waste), near field degradation, gas production and radionuclide release may be impacted by microbial activity and vice versa. In this respect questions arise such as: - Are microorganisms present in a repository and its host rock? - Under which condition are microorganisms active in and around a repository? - In which processes are microorganisms involved? Various in situ experiments in a wide range of geological environments have evidenced the presence of microorganisms. Whether the microorganisms found in these in situ experiments are indigenous or introduced by drilling or/and excavation activities is still controversial. However, recent findings suggest the presence of indigenous microorganisms in Opalinus Clay. To conclusively answer the question about the origin of microorganisms, an international investigation programme has been launched to probe rock samples from the Underground Rock Laboratory at Mont Terri. So far, no metabolic activity has been observed in undisturbed clay rocks. Such activity may have ceased during diagenetic compaction of the sediment as suggested by the pore water composition measured in the Callovian-Oxfordian clayey formation of Bure (France). For the safety case of a repository the origin of microorganisms is of minor importance compared to the understanding of the conditions under which they might be metabolically active. Pore size distribution and connectivity can

  20. The significance of the initiation process parameters and reactor design for maximizing the efficiency of microbial fuel cells

    DEFF Research Database (Denmark)

    Sun, Guotao; Thygesen, Anders; Ale, Marcel Tutor

    2014-01-01

    Microbial fuel cells (MFCs) can be used for electricity generation via bioconversion of wastewater and organic waste substrates. MFCs also hold potential for production of certain chemicals, such as H2 and H2O2. The studies of electricity generation in MFCs have mainly focused on the microbial co...

  1. Response of the Eastern Mediterranean microbial ecosystem to dust and dust affected by acid processing in the atmosphere

    Directory of Open Access Journals (Sweden)

    Michael David Krom

    2016-08-01

    Full Text Available Acid processes in the atmosphere, particularly those caused by anthropogenic acid gases, increase the amount of bioavailable P in dust and hence are predicted to increase microbial biomass and primary productivity when supplied to oceanic surface waters. This is likely to be particularly important in the Eastern Mediterranean Sea (EMS, which is P limited during the winter bloom and N&P co-limited for phytoplankton in summer. However, it is not clear how the acid processes acting on Saharan dust will affect the microbial biomass and primary productivity in the EMS. Here, we carried out bioassay manipulations on EMS surface water on which Saharan dust was added as dust (Z, acid treated dust (ZA, dust plus excess N (ZN and acid treated dust with excess N (ZNA during springtime (May 2012 and measured bacterioplankton biomass, metabolic and other relevant chemical and biological parameters. We show that acid treatment of Saharan dust increased the amount of bioavailable P supplied by a factor of ~40 compared to non-acidified dust (18.4 nmoles P mg-1 dust vs. 0.45 nmoles P mg-1 dust, respectively. The increase in chlorophyll, primary and bacterial productivity for treatments Z and ZA were controlled by the amount of N added with the dust while those for treatments ZN and ZNA (in which excessive N was added were controlled by the amount of P added. These results confirm that the surface waters were N&P co-limited for phytoplankton during springtime. However, total chlorophyll and primary productivity in the acid treated dust additions (ZA and ZNA were less than predicted from that calculated from the amount of the potentially limiting nutrient added. This biological inhibition was interpreted as being due to labile trace metals being added with the acidified dust. A probable cause for this biological inhibition was the addition of dissolved Al, which forms potentially toxic Al nanoparticles when added to seawater. Thus, the effect of anthropogenic acid

  2. Optimization of preservation and processing of sea anemones for microbial community analysis using molecular tools.

    Science.gov (United States)

    Rocha, Joana; Coelho, Francisco J R C; Peixe, Luísa; Gomes, Newton C M; Calado, Ricardo

    2014-11-11

    For several years, knowledge on the microbiome associated with marine invertebrates was impaired by the challenges associated with the characterization of bacterial communities. With the advent of culture independent molecular tools it is possible to gain new insights on the diversity and richness of microorganisms associated with marine invertebrates. In the present study, we evaluated if different preservation and processing methodologies (prior to DNA extraction) can affect the bacterial diversity retrieved from snakelocks anemone Anemonia viridis. Denaturing gradient gel electrophoresis (DGGE) community fingerprints were used as proxy to determine the bacterial diversity retrieved (H'). Statistical analyses indicated that preservation significantly affects H'. The best approach to preserve and process A. viridis biomass for bacterial community fingerprint analysis was flash freezing in liquid nitrogen (preservation) followed by the use of a mechanical homogenizer (process), as it consistently yielded higher H'. Alternatively, biomass samples can be processed fresh followed by cell lyses using a mechanical homogenizer or mortar &pestle. The suitability of employing these two alternative procedures was further reinforced by the quantification of the 16S rRNA gene; no significant differences were recorded when comparing these two approaches and the use of liquid nitrogen followed by processing with a mechanical homogenizer.

  3. Comprehensive microbial analysis of combined mesophilic anaerobic-thermophilic aerobic process treating high-strength food wastewater.

    Science.gov (United States)

    Jang, Hyun Min; Ha, Jeong Hyub; Park, Jong Moon; Kim, Mi-Sun; Sommer, Sven G

    2015-04-15

    A combined mesophilic anaerobic-thermophilic aerobic process was used to treat high-strength food wastewater in this study. During the experimental period, most of solid residue from the mesophilic anaerobic reactor (R1) was separated by centrifugation and introduced into the thermophilic aerobic reactor (R2) for further digestion. Then, thermophilic aerobically-digested sludge was reintroduced into R1 to enhance reactor performance. The combined process was operated with two different Runs: Run I with hydraulic retention time (HRT) = 40 d (corresponding OLR = 3.5 kg COD/m(3) d) and Run II with HRT = 20 d (corresponding OLR = 7 kg COD/m(3)). For a comparison, a single-stage mesophilic anaerobic reactor (R3) was operated concurrently with same OLRs and HRTs as the combined process. During the overall digestion, all reactors showed high stability without pH control. The combined process demonstrated significantly higher organic matter removal efficiencies (over 90%) of TS, VS and COD and methane production than did R3. Quantitative real-time PCR (qPCR) results indicated that higher populations of both bacteria and archaea were maintained in R1 than in R3. Pyrosequencing analysis revealed relatively high abundance of phylum Actinobacteria in both R1 and R2, and a predominance of phyla Synergistetes and Firmicutes in R3 during Run II. Furthermore, R1 and R2 shared genera (Prevotella, Aminobacterium, Geobacillus and Unclassified Actinobacteria), which suggests synergy between mesophilic anaerobic digestion and thermophilic aerobic digestion. For archaea, in R1 methanogenic archaea shifted from genus Methanosaeta to Methanosarcina, whereas genera Methanosaeta, Methanobacterium and Methanoculleus were predominant in R3. The results demonstrated dynamics of key microbial populations that were highly consistent with an enhanced reactor performance of the combined process. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Processing efficiency theory in children: working memory as a mediator between trait anxiety and academic performance.

    Science.gov (United States)

    Owens, Matthew; Stevenson, Jim; Norgate, Roger; Hadwin, Julie A

    2008-10-01

    Working memory skills are positively associated with academic performance. In contrast, high levels of trait anxiety are linked with educational underachievement. Based on Eysenck and Calvo's (1992) processing efficiency theory (PET), the present study investigated whether associations between anxiety and educational achievement were mediated via poor working memory performance. Fifty children aged 11-12 years completed verbal (backwards digit span; tapping the phonological store/central executive) and spatial (Corsi blocks; tapping the visuospatial sketchpad/central executive) working memory tasks. Trait anxiety was measured using the State-Trait Anxiety Inventory for Children. Academic performance was assessed using school administered tests of reasoning (Cognitive Abilities Test) and attainment (Standard Assessment Tests). The results showed that the association between trait anxiety and academic performance was significantly mediated by verbal working memory for three of the six academic performance measures (math, quantitative and non-verbal reasoning). Spatial working memory did not significantly mediate the relationship between trait anxiety and academic performance. On average verbal working memory accounted for 51% of the association between trait anxiety and academic performance, while spatial working memory only accounted for 9%. The findings indicate that PET is a useful framework to assess the impact of children's anxiety on educational achievement.

  5. The Ku80 carboxy terminus stimulates joining and artemis-mediated processing of DNA ends

    DEFF Research Database (Denmark)

    Weterings, Eric; Verkaik, Nicole S; Keijzers, Guido

    2008-01-01

    Repair of DNA double-strand breaks (DSBs) is predominantly mediated by nonhomologous end joining (NHEJ) in mammalian cells. NHEJ requires binding of the Ku70-Ku80 heterodimer (Ku70/80) to the DNA ends and subsequent recruitment of the DNA-dependent protein kinase catalytic subunit (DNA-PK(CS)) an......Repair of DNA double-strand breaks (DSBs) is predominantly mediated by nonhomologous end joining (NHEJ) in mammalian cells. NHEJ requires binding of the Ku70-Ku80 heterodimer (Ku70/80) to the DNA ends and subsequent recruitment of the DNA-dependent protein kinase catalytic subunit (DNA......-PK(CS)) and the XRCC4/ligase IV complex. Activation of the DNA-PK(CS) serine/threonine kinase requires an interaction with Ku70/80 and is essential for NHEJ-mediated DSB repair. In contrast to previous models, we found that the carboxy terminus of Ku80 is not absolutely required for the recruitment and activation...... was phosphorylated to normal levels. This resulted in severely reduced levels of Artemis nuclease activity in vivo and in vitro. We therefore conclude that the Ku80 carboxy terminus is important to support DNA-PK(CS) autophosphorylation at specific sites, which facilitates DNA end processing by the Artemis...

  6. Plasmon point spread functions: How do we model plasmon-mediated emission processes?

    Science.gov (United States)

    Willets, Katherine A.

    2014-02-01

    A major challenge with studying plasmon-mediated emission events is the small size of plasmonic nanoparticles relative to the wavelength of light. Objects smaller than roughly half the wavelength of light will appear as diffraction-limited spots in far-field optical images, presenting a significant experimental challenge for studying plasmonic processes on the nanoscale. Super-resolution imaging has recently been applied to plasmonic nanosystems and allows plasmon-mediated emission to be resolved on the order of ˜5 nm. In super-resolution imaging, a diffraction-limited spot is fit to some model function in order to calculate the position of the emission centroid, which represents the location of the emitter. However, the accuracy of the centroid position strongly depends on how well the fitting function describes the data. This Perspective discusses the commonly used two-dimensional Gaussian fitting function applied to super-resolution imaging of plasmon-mediated emission, then introduces an alternative model based on dipole point spread functions. The two fitting models are compared and contrasted for super-resolution imaging of nanoparticle scattering/luminescence, surface-enhanced Raman scattering, and surface-enhanced fluorescence.

  7. Novel MBR_based main stream biological nutrient removal process: high performance and microbial community.

    Science.gov (United States)

    Zhang, Chuanyi; Xu, Xinhai; Zhao, Kuixia; Tang, Lianggang; Zou, Siqi; Yuan, Limei

    2018-02-01

    For municipal wastewater treatment, main stream biological nutrient removal (BNR) process is becoming more and more important. This lab-scale study, novel MBR_based BNR processes (named A 2 N-MBR and A 2 NO-MBR) were built. Comparison of the COD removal, results obtained demonstrated that COD removal efficiencies were almost the same in three processes, with effluent concentration all bellowed 30 mg L -1 . However, the two-sludge systems (A 2 N-MBR and A 2 NO-MBR) had an obvious advantage over the A 2 /O for denitrification and phosphorus removal, with the average TP removal rates of 91.20, 98.05% and TN removal rates of 73.00, 79.49%, respectively, higher than that of 86.45 and 61.60% in A 2 /O process. Illumina Miseq sequencing revealed that Candidatus_Accumulibacter, which is capable of using nitrate as an electron acceptor for phosphorus and nitrogen removal simultaneously, was the dominant phylum in both A 2 N-MBR and A 2 NO-MBR process, accounting for 28.74 and 23.98%, respectively. Distinguishingly, major organism groups related to nitrogen and phosphorus removal in A 2 /O system were Anaerolineaceae_uncultured, Saprospiraceae_uncultured and Thauera, with proportions of 11.31, 8.56 and 5.00%, respectively. Hence, the diversity of dominant PAOs group was likely responsible for the difference in nitrogen and phosphorus removal in the three processes.

  8. Investigation on biochemical compositional changes during the microbial fermentation process of Fu brick tea by LC-MS based metabolomics.

    Science.gov (United States)

    Xu, Jie; Hu, Feng-Lin; Wang, Wei; Wan, Xiao-Chun; Bao, Guan-Hu

    2015-11-01

    Fu brick tea (FBT) is a unique post-fermented tea product which is fermented with fungi during the manufacturing process. In this study, we investigated the biochemical compositional changes occurring during the microbial fermentation process (MFP) of FBT based on non-targeted LC-MS, which was a comprehensive and unbiased methodology. Our data analysis took a two-phase approach: (1) comparison of FBT with other tea products using PCA analysis to exhibit the characteristic effect of MFP on the formation of Fu brick tea and (2) comparison of tea samples throughout the MFP of FBT to elucidate the possible key metabolic pathways produced by the fungi. Non-targeted LC-MS analysis clearly distinguished FBT with other tea samples and highlighted some interesting metabolic pathways during the MFP including B ring fission catechin. Our study demonstrated that those fungi had a significant influence on the biochemical profiles in the FBT and consequently contributed to its unique quality. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Performance and microbial community structures of hydrolysis acidification process treating azo and anthraquinone dyes in different stages.

    Science.gov (United States)

    Liu, Na; Xie, Xuehui; Yang, Bo; Zhang, Qingyun; Yu, Chengzhi; Zheng, Xiulin; Xu, Leyi; Li, Ran; Liu, Jianshe

    2017-01-01

    In this study, performance of hydrolysis acidification process treating simulated dyeing wastewater containing azo and anthraquinone dyes in different stages was investigated. The decolorization ratio, COD Cr removal ratio, BOD 5 /COD Cr value, and volatile fatty acids (VFAs) production were almost better in stage 1 than that in stage 2. Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) confirmed the biodegradation of Reactive Black 5 (RB5) and Remazol Brilliant Blue R (RBBR) in hydrolysis acidification process. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analyses revealed that significant difference of microbial community structures existed in stage 1 and 2. The dominant species in stage 1 was related to Bacteroidetes group, while the dominant species in stage 2 was related to Bacteroidetes and Firmicutes groups. From the results, it could be speculated that different dyes' structures might have significant influence on the existence and function of different bacterial species, which might supply information for bacteria screening and acclimation in the treatment of actual dyeing wastewater.

  10. Sex differences in face processing are mediated by handedness and sexual orientation.

    Science.gov (United States)

    Brewster, Paul W H; Mullin, Caitlin R; Dobrin, Roxana A; Steeves, Jennifer K E

    2011-03-01

    Previous research has demonstrated sex differences in face processing at both neural and behavioural levels. The present study examined the role of handedness and sexual orientation as mediators of this effect. We compared the performance of LH (left-handed) and RH (right-handed) heterosexual and homosexual male and female participants on a face recognition memory task. Our main findings were that homosexual males have better face recognition memory than both heterosexual males and homosexual women. We also demonstrate better face processing in women than in men. Finally, LH heterosexual participants had better face recognition than LH homosexual participants and also tended to be better than RH heterosexual participants. These findings are consistent with differences in the organisation and laterality of face-processing mechanisms as a function of sex, handedness, and sexual orientation.

  11. Impact of high-pressure processing on the microbial ecology of foods

    Science.gov (United States)

    A new report released by the USDA’s Economic Research Service estimates the cost of foodborne illnesses in the U.S. tops $15.6 billion (USDA, 2014). Food can be contaminated by human pathogens anywhere in the farm to table continuum. Thermal processing is the most common intervention technology pra...

  12. Detection of microbial biofilms on food processing surfaces: Hyperspectral fluorescence imaging study

    Science.gov (United States)

    We used a portable hyperspectral fluorescence imaging system to evaluate biofilm formations on four types of food processing surface materials including stainless steel, polypropylene used for cutting boards, and household counter top materials such as formica and granite. The objective of this inve...

  13. Polyol-mediated thermolysis process for the synthesis of MgO nanoparticles and nanowires

    International Nuclear Information System (INIS)

    Subramania, A; Kumar, G Vijaya; Priya, A R Sathiya; Vasudevan, T

    2007-01-01

    The main aim of this work is to prepare MgO nanoparticles and nanowires by a novel polyol-mediated thermolysis (PMT) process. The influence of different mole concentration of magnesium acetate, polyvinyl pyrrolidone (PVP; capping agent) and ethylene glycol (EG; solvent as well as reducing agent) on the formation of nanoparticles and nanowires and the effect of calcination on the crystalline size of the samples were also examined. The resultant oxide structure, thermal behaviour, size and shape have been studied using x-ray diffraction (XRD) studies, thermal (TG/DTA) analysis and scanning electron microscopy (SEM)/transmission electron microscopy (TEM) respectively

  14. Polyol-mediated thermolysis process for the synthesis of MgO nanoparticles and nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Subramania, A; Kumar, G Vijaya; Priya, A R Sathiya; Vasudevan, T [Advanced Materials Research Lab, Department of Industrial Chemistry, Alagappa University, Karaikudi-630 003 (India)

    2007-06-06

    The main aim of this work is to prepare MgO nanoparticles and nanowires by a novel polyol-mediated thermolysis (PMT) process. The influence of different mole concentration of magnesium acetate, polyvinyl pyrrolidone (PVP; capping agent) and ethylene glycol (EG; solvent as well as reducing agent) on the formation of nanoparticles and nanowires and the effect of calcination on the crystalline size of the samples were also examined. The resultant oxide structure, thermal behaviour, size and shape have been studied using x-ray diffraction (XRD) studies, thermal (TG/DTA) analysis and scanning electron microscopy (SEM)/transmission electron microscopy (TEM) respectively.

  15. Polyol-mediated thermolysis process for the synthesis of MgO nanoparticles and nanowires

    Science.gov (United States)

    Subramania, A.; Vijaya Kumar, G.; Sathiya Priya, A. R.; Vasudevan, T.

    2007-06-01

    The main aim of this work is to prepare MgO nanoparticles and nanowires by a novel polyol-mediated thermolysis (PMT) process. The influence of different mole concentration of magnesium acetate, polyvinyl pyrrolidone (PVP; capping agent) and ethylene glycol (EG; solvent as well as reducing agent) on the formation of nanoparticles and nanowires and the effect of calcination on the crystalline size of the samples were also examined. The resultant oxide structure, thermal behaviour, size and shape have been studied using x-ray diffraction (XRD) studies, thermal (TG/DTA) analysis and scanning electron microscopy (SEM)/transmission electron microscopy (TEM) respectively.

  16. Monitoring of microbial hazards at farms, slaughterhouses, and processing lines of swine in Korea.

    Science.gov (United States)

    Rho, M J; Chung, M S; Lee, J H; Park, J

    2001-09-01

    This study was executed to investigate microbiological hazards at swine farms, slaughterhouses, dressing operations, and local markets for the application of the hazard analysis critical control point system in Korea by analyzing total aerobic plate count (APC) and presence of pathogens. Six integrated pig farms and meat packers were selected from six different provinces, and samples were collected from pig carcasses by swabbing and excision methods at the slaughterhouses, processing rooms, and local markets, respectively. APCs of water in water tanks were relatively low, 1.9 to 3.1 log10 CFU/ml; however, they were increased to 4.6 to 6.9 log10 CFU/ml when sampled from water nipples in the pigpen. APCs of feeds in the feed bins and in the pigpens were 4.4 to 5.4 and 5.2 to 6.7 log10 CFU/g, respectively. Salmonella spp., Staphylococcus aureus, and Clostridium perfringens were detected from water and feed sampled in pigpens and pigpen floors. S. aureus was the most frequently detected pathogenic bacteria in slaughterhouses and processing rooms. Listeria monocytogenes and Yersinia enterocolitica were also detected from the processing rooms of the Kyonggi, Kyongsang, and Cheju provinces. Even though APCs were maintained at the low level of 3.0 log10 CFU/g during slaughtering and processing steps, those of final pork products produced by the same companies showed relatively high numbers when purchased from the local market. These results indicated that the cold chain system for transporting and merchandising of pork products was deficient in Korea. Water supply and feed bins in swine farms and individual operations can be identified as critical control points to reduce microbiological hazards in swine farms, slaughterhouses, and processing plants.

  17. Microbial resource management for the mitigation of nitrous oxide emissions from the Partial Nitritation- Anammox process

    DEFF Research Database (Denmark)

    Blum, Jan-Michael

    Urban wastewater treatment plants are designed to remove pathogens and pollutants from wastewater in order to provide sanitation and to protect receiving water bodies from eutrophication. Reactive nitrogen, mainly in the form of ammonium, is one of the components in wastewater that is converted...... to dinitrogen gas during treatment. The Partial Nitritation-Anammox process (PNA) uses the capacity of autotrophic aerobic and anaerobic ammonia oxidizing bacteria (AOB and AnAOB) to perform this task. The process is mainly applied to treat ammonium-rich wastewater streams with low concentrations of organic...... with the specific ammonia removal rate, while during non-aerated phases net N2O production rates were positively correlated with the nitrite concentration (NO2-). Operation of PNA at reduced specific ammonia removal rates is, therefore, a feasible strategy to mitigate N2O emissions. However, when high ammonium...

  18. Microbial weathering processes after release of heavy metals and arsenic from fluvial tailing deposits; Mikrobielle Verwitterungsprozesse bei der Freisetzung von Schwermetallen und Arsen aus fluvialen Tailingablagerungen

    Energy Technology Data Exchange (ETDEWEB)

    Willscher, S. [Technische Univ. Dresden (Germany). Fak. fuer Forst, Geo und Hydrowissenschaften, Inst. fuer Abfallwirtschaft und Altlasten

    2006-07-01

    Microbial processes play an important role in global metal cycles. The microbial weathering of mineral surfaces, including deposited anthropogenic mineral remainders, is a natural occurring process, taking place on uncovered dump surfaces as well as in deeper zones of dumps. Such weathering processes also occur in metal contaminated soils and sediments. In this work, a sulfidic fluvial tailing sediment was investigated for its acidity and salinity generating potential and the subsequent mobilisation of heavy metals, generated by biogeochemical processes. The long-term risks of such a deposit were evaluated. Unstabilised deposits of such materials can generate a considerable contamination of the surrounding ground and surface water. It could be shown in the experiments that in acid generating dumps and tailing materials besides the well known acidophilic autotrophs also acidotolerant heterotrophic microorganisms play a role in the mobilisation of metals. (orig.)

  19. Relationship between microbial community dynamics and process performance during thermophilic sludge bioleaching.

    Science.gov (United States)

    Chen, Shen-Yi; Chou, Li-Chieh

    2016-08-01

    Heavy metals can be removed from the sludge using bioleaching technologies at thermophilic condition, thereby providing an option for biotreatment of wasted sludge generated from wastewater treatment. The purposes of this study were to establish a molecular biology technique, real-time PCR, for the detection and enumeration of the sulfur-oxidizing bacteria during the thermophilic sludge bioleaching. The 16S rRNA gene for real-time PCR quantification targeted the bioleaching bacteria: Sulfobacillus thermosulfidooxidans, Sulfobacillus acidophilus, and Acidithiobacillus caldus. The specificity and stringency for thermophilic sulfur-oxidizing bacteria were tested before the experiments of monitoring the bacterial community, bacterial number during the thermophilic sludge bioleaching and the future application on testing various environmental samples. The results showed that S. acidophilus was identified as the dominant sulfur-oxidizing bacteria, while A. caldus and S. thermosulfidooxidans occurred in relatively low numbers. The total number of the sulfur-oxidizing bacteria increased during the thermophilic bioleaching process. Meanwhile, the decrease of pH, production of sulfate, degradation of SS/VSS, and solubilization of heavy metal were found to correlate well with the population of thermophilic sulfur-oxidizing bacteria during the bioleaching process. The real-time PCR used in this study is a suitable method to monitor numbers of thermophilic sulfur-oxidizing bacteria during the bioleaching process.

  20. [Key microbial processes in nitrous oxide emissions of agricultural soil and mitigation strategies].

    Science.gov (United States)

    Zhu, Yong-Guan; Wang, Xiao-Hui; Yang, Xiao-Ru; Xu, Hui-Juan; Jia, Yan

    2014-02-01

    Nitrous oxide (N2O) is a powerful atmospheric greenhouse gas, which does not only have a strong influence on the global climate change but also depletes the ozone layer and induces the enhancement of ultraviolet radiation to ground surface, so numerous researches have been focused on global climate change and ecological environmental change. Soil is the foremost source of N2O emissions to the atmosphere, and approximately two-thirds of these emissions are generally attributed to microbiological processes including bacterial and fungal denitrification and nitrification processes, largely as a result of the application of nitrogenous fertilizers. Here the available knowledge concerning the research progress in N2O production in agricultural soils was reviewed, including denitrification, nitrification, nitrifier denitrification and dissimilatory nitrate reduction to ammonium, and the abiotic (including soil pH, organic and inorganic nitrogen, organic matter, soil humidity and temperature) and biotic factors that have direct and indirect effects on N2O fluxes from agricultural soils were also summarized. In addition, the strategies for mitigating N2O emissions and the future research direction were proposed. Therefore, these studies are expected to provide valuable and scientific evidence for the study on mitigation strategies for the emission of greenhouse gases, adjustment of nitrogen transformation processes and enhancement of nitrogen use efficiency.

  1. Transmission as a basic process in microbial biology. Lwoff Award Prize Lecture.

    Science.gov (United States)

    Baquero, Fernando

    2017-11-01

    Transmission is a basic process in biology and evolution, as it communicates different biological entities within and across hierarchical levels (from genes to holobionts) both in time and space. Vertical descent, replication, is transmission of information across generations (in the time dimension), and horizontal descent is transmission of information across compartments (in the space dimension). Transmission is essentially a communication process that can be studied by analogy of the classic information theory, based on 'emitters', 'messages' and 'receivers'. The analogy can be easily extended to the triad 'emigration', 'migration' and 'immigration'. A number of causes (forces) determine the emission, and another set of causes (energies) assures the reception. The message in fact is essentially constituted by 'meaningful' biological entities. A DNA sequence, a cell and a population have a semiotic dimension, are 'signs' that are eventually recognized (decoded) and integrated by receiver biological entities. In cis-acting or unenclosed transmission, the emitters and receivers correspond to separated entities of the same hierarchical level; in trans-acting or embedded transmission, the information flows between different, but frequently nested, hierarchical levels. The result (as in introgressive events) is constantly producing innovation and feeding natural selection, influencing also the evolution of transmission processes. This review is based on the concepts presented at the André Lwoff Award Lecture in the FEMS Microbiology Congress in Maastricht in 2015. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. An Examination of Mediators of the Transfer of Cognitive Speed of Processing Training to Everyday Functional Performance

    OpenAIRE

    Edwards, Jerri D.; Ruva, Christine L.; O’Brien, Jennifer L.; Haley, Christine B.; Lister, Jennifer J.

    2012-01-01

    The purpose of these analyses was to examine mediators of the transfer of cognitive speed of processing training to improved everyday functional performance (Edwards, Wadley, Vance, Roenker, & Ball, 2005). Cognitive speed of processing and visual attention (as measured by the Useful Field of View Test; UFOV) were examined as mediators of training transfer. Secondary data analyses were conducted from the Staying Keen in Later Life (SKILL) study, a randomized cohort study including 126 communit...

  3. Acclimation to extremely high ammonia levels in continuous biomethanation process and the associated microbial community dynamics

    DEFF Research Database (Denmark)

    Tian, Hailin; Fotidis, Ioannis; Mancini, Enrico

    2018-01-01

    Acclimatized anaerobic communities to high ammonia levels can offer a solution to the ammonia toxicity problem in biogas reactors. In the current study, a stepwise acclimation strategy up to 10 g NH4+-N L−1, was performed in mesophilic (37 ± 1 °C) continuously stirred tank reactors. The reactors...... change throughout the ammonia acclimation process. Clostridium ultunense, a syntrophic acetate oxidizing bacteria, increased significantly alongside with hydrogenotrophic methanogen Methanoculleus spp., indicating strong hydrogenotrophic methanogenic activity at extreme ammonia levels (>7 g NH4+-N L−1...

  4. Relationship of microbial processes to the fate of transuranic elements in soil

    International Nuclear Information System (INIS)

    Wildung, R.E.; Drucker, H.

    1975-09-01

    Any assessment of the long-term behavior of the transuranics in the terrestrial environment must be based on determination of the factors influencing solubility in soil. The influence of soil properties and abiotic and biotic processes on the long-term solubility of the transuranics entering soils is reviewed in detail. Principal emphasis is directed toward the role of soil microorganisms. Emphasis is given to plutonium, but, where possible, the available information is used to discuss long-term behavior of other transuranics

  5. Text Comprehension Mediates Morphological Awareness, Syntactic Processing, and Working Memory in Predicting Chinese Written Composition Performance

    Science.gov (United States)

    Guan, Connie Qun; Ye, Feifei; Wagner, Richard K.; Meng, Wanjin; Leong, Che Kan

    2014-01-01

    The goal of the present study was to test opposing views about four issues concerning predictors of individual differences in Chinese written composition: (a) Whether morphological awareness, syntactic processing, and working memory represent distinct and measureable constructs in Chinese or are just manifestations of general language ability; (b) whether they are important predictors of Chinese written composition, and if so, the relative magnitudes and independence of their predictive relations; (c) whether observed predictive relations are mediated by text comprehension; and (d) whether these relations vary or are developmentally invariant across three years of writing development. Based on analyses of the performance of students in grades 4 (n = 246), 5 (n = 242) and 6 (n = 261), the results supported morphological awareness, syntactic processing, and working memory as distinct yet correlated abilities that made independent contributions to predicting Chinese written composition, with working memory as the strongest predictor. However, predictive relations were mediated by text comprehension. The final model accounted for approximately 75 percent of the variance in Chinese written composition. The results were largely developmentally invariant across the three grades from which participants were drawn. PMID:25530630

  6. Longitudinal Mediation of Processing Speed on Age-Related Change in Memory and Fluid Intelligence

    Science.gov (United States)

    Robitaille, Annie; Piccinin, Andrea M.; Muniz, Graciela; Hoffman, Lesa; Johansson, Boo; Deeg, Dorly J.H.; Aartsen, Marja J.; Comijs, Hannie C.; Hofer, Scott M.

    2014-01-01

    Age-related decline in processing speed has long been considered a key driver of cognitive aging. While the majority of empirical evidence for the processing speed hypothesis has been obtained from analyses of between-person age differences, longitudinal studies provide a direct test of within-person change. Using recent developments in longitudinal mediation analysis, we examine the speed–mediation hypothesis at both the within- and between-person levels in two longitudinal studies, LASA and OCTO-Twin. We found significant within-person indirect effects of change in age, such that increasing age was related to lower speed which, in turn, relates to lower performance across repeated measures on other cognitive outcomes. Although between-person indirect effects were also significant in LASA, they were not in OCTO-Twin. These differing magnitudes of direct and indirect effects across levels demonstrate the importance of separating between- and within-person effects in evaluating theoretical models of age-related change. PMID:23957224

  7. Understanding the core of RNA interference: The dynamic aspects of Argonaute-mediated processes

    KAUST Repository

    Zhu, Lizhe

    2016-10-05

    At the core of RNA interference, the Argonaute proteins (Ago) load and utilize small guide nucleic acids to silence mRNAs or cleave foreign nucleic acids in a sequence specific manner. In recent years, based on extensive structural studies of Ago and its interaction with the nucleic acids, considerable progress has been made to reveal the dynamic aspects of various Ago-mediated processes. Here we review these novel insights into the guide-strand loading, duplex unwinding, and effects of seed mismatch, with a focus on two representative Agos, the human Ago 2 (hAgo2) and the bacterial Thermus thermophilus Ago (TtAgo). In particular, comprehensive molecular simulation studies revealed that although sharing similar overall structures, the two Agos have vastly different conformational landscapes and guide-strand loading mechanisms because of the distinct rigidity of their L1-PAZ hinge. Given the central role of the PAZ motions in regulating the exposure of the nucleic acid binding channel, these findings exemplify the importance of protein motions in distinguishing the overlapping, yet distinct, mechanisms of Ago-mediated processes in different organisms.

  8. Attentional selection of relative SF mediates global versus local processing: evidence from EEG.

    Science.gov (United States)

    Flevaris, Anastasia V; Bentin, Shlomo; Robertson, Lynn C

    2011-06-13

    Previous research on functional hemispheric differences in visual processing has associated global perception with low spatial frequency (LSF) processing biases of the right hemisphere (RH) and local perception with high spatial frequency (HSF) processing biases of the left hemisphere (LH). The Double Filtering by Frequency (DFF) theory expanded this hypothesis by proposing that visual attention selects and is directed to relatively LSFs by the RH and relatively HSFs by the LH, suggesting a direct causal relationship between SF selection and global versus local perception. We tested this idea in the current experiment by comparing activity in the EEG recorded at posterior right and posterior left hemisphere sites while participants' attention was directed to global or local levels of processing after selection of relatively LSFs versus HSFs in a previous stimulus. Hemispheric asymmetry in the alpha band (8-12 Hz) during preparation for global versus local processing was modulated by the selected SF. In contrast, preparatory activity associated with selection of SF was not modulated by the previously attended level (global/local). These results support the DFF theory that top-down attentional selection of SF mediates global and local processing.

  9. Respiratory symptoms among industrial workers exposed to water aerosol. A pilot study of process water and air microbial quality

    Directory of Open Access Journals (Sweden)

    Bożena Krogulska

    2013-02-01

    Full Text Available Background: The frequency of respiratory symptoms in workers exposed to water aerosol was evaluated along with the preliminary assessment of microbiological contamination of air and water used in glass processing plants. Material and Methods: A questionnaire survey was conducted in 131 workers from 9 glass processing plants. Questions focused on working conditions, respiratory symptoms and smoking habits. A pilot study of air and water microbiological contamination in one glass processing plant was performed. Water samples were tested for Legionella in accordance with EN ISO 11731-2:2008 and for total colony count according to PN-EN ISO 6222:2004. Air samples were tested for total numbers of molds and mildews. Results: During the year preceding the survey acute respiratory symptoms occurred in 28.2% of participants, while chronic symptoms were reported by 29% of respondents. Increased risks of cough and acute symptoms suggestive of pneumonia were found among the respondents working at a distance up to 20 m from the source of water aerosol compared to other workers (OR = 2.7, with no difference in the frequency of other symptoms. A microbiological analysis of water samples from selected glass plant revealed the presence of L. pneumophila, exceeding 1000 cfu/100 ml. The number of bacteria and fungi detected in air samples (above 1000 cfu/m3 suggested that water aerosol at workplaces can be one of the sources of the air microbial contamination. Conclusions: The questionnaire survey revealed an increased risk of cough and acute symptoms suggestive of pneumonia in the group working at a shortest distance form the source of water aerosol. Med Pr 2013;64(1:47–55

  10. Use of an uncertainty analysis for genome-scale models as a prediction tool for microbial growth processes in subsurface environments.

    Science.gov (United States)

    Klier, Christine

    2012-03-06

    The integration of genome-scale, constraint-based models of microbial cell function into simulations of contaminant transport and fate in complex groundwater systems is a promising approach to help characterize the metabolic activities of microorganisms in natural environments. In constraint-based modeling, the specific uptake flux rates of external metabolites are usually determined by Michaelis-Menten kinetic theory. However, extensive data sets based on experimentally measured values are not always available. In this study, a genome-scale model of Pseudomonas putida was used to study the key issue of uncertainty arising from the parametrization of the influx of two growth-limiting substrates: oxygen and toluene. The results showed that simulated growth rates are highly sensitive to substrate affinity constants and that uncertainties in specific substrate uptake rates have a significant influence on the variability of simulated microbial growth. Michaelis-Menten kinetic theory does not, therefore, seem to be appropriate for descriptions of substrate uptake processes in the genome-scale model of P. putida. Microbial growth rates of P. putida in subsurface environments can only be accurately predicted if the processes of complex substrate transport and microbial uptake regulation are sufficiently understood in natural environments and if data-driven uptake flux constraints can be applied.

  11. Effect of microbial processes on transuranium elements behaviour in soil, plants and animal organism

    International Nuclear Information System (INIS)

    Uajldung, R.Eh.; Garlend, T.P.

    1985-01-01

    Results of preliminary studies discussed in the present paper bring about the supposition that concentration and chemical from of an element in a plant play an essential role in variation of its availability for animals consuming plants. That is why any assessment of long-term behaviour of transuranium elements in terrestrialenvironment should be based on determination of factors affecting solubility and forms of soluble compounds in soil. These factors include concentration and chemical form of the element migrating to soil; effect of the properties of soil on element distribution between solid and liquid phases; effect soil processes on kinetics of sorption reactions, concentration of transuranium elements, forms of soluble and non-soluble chemical compounds

  12. A commercial microbial enhanced oil recovery process: statistical evaluation of a multi-project database

    Energy Technology Data Exchange (ETDEWEB)

    Portwood, J.T.

    1995-12-31

    This paper discusses a database of information collected and organized during the past eight years from 2,000 producing oil wells in the United States, all of which have been treated with special applications techniques developed to improve the effectiveness of MEOR technology. The database, believed to be the first of its kind, has been generated for the purpose of statistically evaluating the effectiveness and economics of the MEOR process in a wide variety of oil reservoir environments, and is a tool that can be used to improve the predictability of treatment response. The information in the database has also been evaluated to determine which, if any, reservoir characteristics are dominant factors in determining the applicability of MEOR.

  13. Anaerobic digestion of nitrogen rich poultry manure: Impact of thermophilic biogas process on metal release and microbial resistances.

    Science.gov (United States)

    Anjum, Reshma; Grohmann, Elisabeth; Krakat, Niclas

    2017-02-01

    Poultry manure is a nitrogen rich fertilizer, which is usually recycled and spread on agricultural fields. Due to its high nutrient content, chicken manure is considered to be one of the most valuable animal wastes as organic fertilizer. However, when chicken litter is applied in its native form, concerns are raised as such fertilizers also include high amounts of antibiotic resistant pathogenic Bacteria and heavy metals. We studied the impact of an anaerobic thermophilic digestion process on poultry manure. Particularly, microbial antibiotic resistance profiles, mobile genetic elements promoting the resistance dissemination in the environment as well as the presence of heavy metals were focused in this study. The initiated heat treatment fostered a community shift from pathogenic to less pathogenic bacterial groups. Phenotypic and molecular studies demonstrated a clear reduction of multiple resistant pathogens and self-transmissible plasmids in the heat treated manure. That treatment also induced a higher release of metals and macroelements. Especially, Zn and Cu exceeded toxic thresholds. Although the concentrations of a few metals reached toxic levels after the anaerobic thermophilic treatment, the quality of poultry manure as organic fertilizer may raise significantly due to the elimination of antibiotic resistance genes (ARG) and self-transmissible plasmids. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Biochemical process of ureolysis-based microbial CaCO3 precipitation and its application in self-healing concrete.

    Science.gov (United States)

    Xu, Jing; Wang, Xianzhi; Wang, Binbin

    2018-04-01

    Urea hydrolysis has already been considered as the most effective pathway for microbially induced CaCO 3 precipitation (MICP). The present work first studied the combination of several key factors including initial pH, temperature, and dosage of urea, which contribute to the biochemical process of MICP. Under an amiable condition of pH and temperature, the dosage of urea has a significant impact on the rate of urea degradation and CaCO 3 precipitation. A bacteria-based self-healing system was developed by loading healing agents on ceramsite carriers. The self-healing efficiency was evaluated by visual inspection on crack closure, compressive strength regain, and capillary water absorption. A preferable healing effectiveness was obtained when the bacteria and organic nutrients were co-immobilized in carriers. Image analysis showed that cracks up to 273 μm could be healed with a crack closure ratio of 86% in 28 days. The compressive strength regain increased 24% and the water absorption coefficient decreased 27% compared to the reference. The findings indicated a promising application of ureolysis-based MICP in restoring the mechanical properties and enhancing the durability of concrete.

  15. Evaluating the influence of process parameters on soluble microbial products formation using response surface methodology coupled with grey relational analysis.

    Science.gov (United States)

    Xu, Juan; Sheng, Guo-Ping; Luo, Hong-Wei; Fang, Fang; Li, Wen-Wei; Zeng, Raymond J; Tong, Zhong-Hua; Yu, Han-Qing

    2011-01-01

    Soluble microbial products (SMPs) present a major part of residual chemical oxygen demand (COD) in the effluents from biological wastewater treatment systems, and the SMP formation is greatly influenced by a variety of process parameters. In this study, response surface methodology (RSM) coupled with grey relational analysis (GRA) method was used to evaluate the effects of substrate concentration, temperature, NH(4)(+)-N concentration and aeration rate on the SMP production in batch activated sludge reactors. Carbohydrates were found to be the major component of SMP, and the influential priorities of these factors were: temperature>substrate concentration > aeration rate > NH(4)(+)-N concentration. On the basis of the RSM results, the interactive effects of these factors on the SMP formation were evaluated, and the optimal operating conditions for a minimum SMP production in such a batch activated sludge system also were identified. These results provide useful information about how to control the SMP formation of activated sludge and ensure the bioreactor high-quality effluent. Copyright © 2010 Elsevier Ltd. All rights reserved.

  16. Biohydrogen production from purified terephthalic acid (PTA) processing wastewater by anaerobic fermentation using mixed microbial communities

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ge-Fu; Wu, Peng; Wei, Qun-Shan; Lin, Jian-yi; Liu, Hai-Ning [Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Gao, Yan-Li [China University of Geosciences, Wuhan 430074 (China)

    2010-08-15

    Purified terephthalic acid (PTA) processing wastewater was evaluated as a fermentable substrate for hydrogen (H{sub 2}) production with simultaneous wastewater treatment by dark-fermentation process in a continuous stirred-tank reactor (CSTR) with selectively enriched acidogenic mixed consortia under continuous flow condition in this paper. The inoculated sludge used in the reactor was excess sludge taken from a second settling tank in a local wastewater treatment plant. Under the conditions of the inoculants not less than 6.3 gVSS/L, the organic loading rate (OLR) of 16 kgCOD/m{sup 3} d, hydraulic retention time (HRT) of 6 h and temperature of (35 {+-} 1) C, when the pH value, alkalinity and oxidation-reduction potential (ORP) of the effluent ranged from 4.2 to 4.4, 280 to 350 mg CaCO{sub 3}/L, and -220 to -250 mV respectively, soluble metabolites were predominated by acetate and ethanol, with smaller quantities of propionate, butyrate and valerate. Stable ethanol-type fermentation was formed with the sum of ethanol and acetate concentration ratio of 70.31% to the total liquid products after 25 days operation. The H{sub 2} volume content was estimated to be 48-53% of the total biogas and the biogas was free of methane throughout the study. The average biomass concentration was estimated to be 10.82 gVSS/L, which favored H{sub 2} production efficiently. The rate of chemical oxygen demand (COD) removal reached at about 45% and a specific H{sub 2} production rate achieved 0.073 L/gMLVSS d in the study. This CSTR system showed a promising high-efficient bioprocess for H{sub 2} production from high-strength chemical wastewater. (author)

  17. Psychological processes mediate the impact of familial risk, social circumstances and life events on mental health.

    Science.gov (United States)

    Kinderman, Peter; Schwannauer, Matthias; Pontin, Eleanor; Tai, Sara

    2013-01-01

    Despite widespread acceptance of the 'biopsychosocial model', the aetiology of mental health problems has provoked debate amongst researchers and practitioners for decades. The role of psychological factors in the development of mental health problems remains particularly contentious, and to date there has not been a large enough dataset to conduct the necessary multivariate analysis of whether psychological factors influence, or are influenced by, mental health. This study reports on the first empirical, multivariate, test of the relationships between the key elements of the biospychosocial model of mental ill-health. Participants were 32,827 (age 18-85 years) self-selected respondents from the general population who completed an open-access online battery of questionnaires hosted by the BBC. An initial confirmatory factor analysis was performed to assess the adequacy of the proposed factor structure and the relationships between latent and measured variables. The predictive path model was then tested whereby the latent variables of psychological processes were positioned as mediating between the causal latent variables (biological, social and circumstantial) and the outcome latent variables of mental health problems and well-being. This revealed an excellent fit to the data, S-B χ(2) (3199, N = 23,397) = 126654.8, pmental health difficulties, social deprivation, and traumatic or abusive life-experiences all strongly predicted higher levels of anxiety and depression. However, these relationships were strongly mediated by psychological processes; specifically lack of adaptive coping, rumination and self-blame. These results support a significant revision of the biopsychosocial model, as psychological processes determine the causal impact of biological, social, and circumstantial risk factors on mental health. This has clear implications for policy, education and clinical practice as psychological processes such as rumination and self-blame are amenable to evidence

  18. The CB1 Receptor as an Important Mediator of Hedonic Reward Processing

    Science.gov (United States)

    Friemel, Chris M; Zimmer, Andreas; Schneider, Miriam

    2014-01-01

    The endocannabinoid (ECB) system has emerged recently as a key mediator for reward processing. It is well known that cannabinoids affect appetitive learning processes and can induce reinforcing and rewarding effects. However, the involvement of the ECB system in hedonic aspects of reward-related behavior is not completely understood. With the present study, we investigated the modulatory role of the ECB system on hedonic perception, measured by the pleasure attenuated startle (PAS) paradigm for a palatable food reward. Here, a conditioned odor is thought to induce a pleasant affective state that attenuates an aversive reflex—the acoustic startle response. Modulatory effects of the CB1 receptor antagonist/inverse agonist SR1411716 and the cannabinoid agonist WIN 55 212-2 on PAS were examined in rats. PAS was also measured in CB1 receptor knockout (KO) and wild-type (WT) mice. Pharmacological inhibition as well as the absence of CB1 receptors was found to reduce PAS, whereas WIN 55 212-2 administration increased PAS. Finally, presentation of a conditioned reward cue was found to induce striatal FosB/ΔFosB expression in WT mice, but not in KO mice, indicating a reduced stimulation of reward-related brain regions in conditioned KO mice by odor presentation. We here show that in addition to our previous studies in rats, PAS may also serve as a valuable and suitable measure to assess hedonic processing in mice. Our data further indicate that the ECB system, and in particular CB1 receptor signaling, appears to be highly important for the mediation of hedonic aspects of reward processing. PMID:24718372

  19. Evaluation of low cost cathode materials for treatment of industrial and food processing wastewater using microbial electrolysis cells

    KAUST Repository

    Tenca, Alberto; Cusick, Roland D.; Schievano, Andrea; Oberti, Roberto; Logan, Bruce E.

    2013-01-01

    Microbial electrolysis cells (MECs) can be used to treat wastewater and produce hydrogen gas, but low cost cathode catalysts are needed to make this approach economical. Molybdenum disulfide (MoS2) and stainless steel (SS) were evaluated

  20. Progress in bioleaching: part B: applications of microbial processes by the minerals industries.

    Science.gov (United States)

    Brierley, Corale L; Brierley, James A

    2013-09-01

    This review presents developments and applications in bioleaching and mineral biooxidation since publication of a previous mini review in 2003 (Olson et al. Appl Microbiol Biotechnol 63:249-257, 2003). There have been discoveries of newly identified acidophilic microorganisms that have unique characteristics for effective bioleaching of sulfidic ores and concentrates. Progress has been made in understanding and developing bioleaching of copper from primary copper sulfide minerals, chalcopyrite, covellite, and enargite. These developments point to low oxidation-reduction potential in concert with thermophilic bacteria and archaea as a potential key to the leaching of these minerals. On the commercial front, heap bioleaching of nickel has been commissioned, and the mineral biooxidation pretreatment of sulfidic-refractory gold concentrates is increasingly used on a global scale to enhance precious metal recovery. New and larger stirred-tank reactors have been constructed since the 2003 review article. One biooxidation-heap process for pretreatment of sulfidic-refractory gold ores was also commercialized. A novel reductive approach to bioleaching nickel laterite minerals has been proposed.

  1. Microbial Production of Short Chain Fatty Acids from Lignocellulosic Biomass: Current Processes and Market

    Directory of Open Access Journals (Sweden)

    Ivan Baumann

    2016-01-01

    Full Text Available Biological production of organic acids from conversion of biomass derivatives has received increased attention among scientists and engineers and in business because of the attractive properties such as renewability, sustainability, degradability, and versatility. The aim of the present review is to summarize recent research and development of short chain fatty acids production by anaerobic fermentation of nonfood biomass and to evaluate the status and outlook for a sustainable industrial production of such biochemicals. Volatile fatty acids (VFAs such as acetic acid, propionic acid, and butyric acid have many industrial applications and are currently of global economic interest. The focus is mainly on the utilization of pretreated lignocellulosic plant biomass as substrate (the carbohydrate route and development of the bacteria and processes that lead to a high and economically feasible production of VFA. The current and developing market for VFA is analyzed focusing on production, prices, and forecasts along with a presentation of the biotechnology companies operating in the market for sustainable biochemicals. Finally, perspectives on taking sustainable product of biochemicals from promise to market introduction are reviewed.

  2. Microbial evaluation of fresh, minimally-processed vegetables and bagged sprouts from chain supermarkets.

    Science.gov (United States)

    Jeddi, Maryam Zare; Yunesian, Masud; Gorji, Mohamad Es'haghi; Noori, Negin; Pourmand, Mohammad Reza; Khaniki, Gholam Reza Jahed

    2014-09-01

    The aim of this study was to evaluate the bacterial and fungal quality of minimally-processed vegetables (MPV) and sprouts. A total of 116 samples of fresh-cut vegetables, ready-to-eat salads, and mung bean and wheat sprouts were randomly collected and analyzed. The load of aerobic mesophilic bacteria was minimum and maximum in the fresh-cut vegetables and fresh mung bean sprouts respectively, corresponding to populations of 5.3 and 8.5 log CFU/g. E. coli O157:H7 was found to be absent in all samples; however,  other E. coli strains were detected in 21 samples (18.1%), and Salmonella spp. were found in one mung bean (3.1%) and one ready-to-eat salad sample (5%). Yeasts were the predominant organisms and were found in 100% of the samples. Geotrichum, Fusarium, and Penicillium spp. were the most prevalent molds in mung sprouts while Cladosporium and Penicillium spp. were most frequently found in ready-to-eat salad samples. According to results from the present study, effective control measures should be implemented to minimize the microbiological contamination of fresh produce sold in Tehran, Iran.

  3. Microbial Evaluation of Fresh, Minimally-processed Vegetables and Bagged Sprouts from Chain Supermarkets

    Science.gov (United States)

    Jeddi, Maryam Zare; Yunesian, Masud; Gorji, Mohamad Es'haghi; Noori, Negin; Pourmand, Mohammad Reza

    2014-01-01

    ABSTRACT The aim of this study was to evaluate the bacterial and fungal quality of minimally-processed vegetables (MPV) and sprouts. A total of 116 samples of fresh-cut vegetables, ready-to-eat salads, and mung bean and wheat sprouts were randomly collected and analyzed. The load of aerobic mesophilic bacteria was minimum and maximum in the fresh-cut vegetables and fresh mung bean sprouts respectively, corresponding to populations of 5.3 and 8.5 log CFU/g. E. coli O157:H7 was found to be absent in all samples; however,  other E. coli strains were detected in 21 samples (18.1%), and Salmonella spp. were found in one mung bean (3.1%) and one ready-to-eat salad sample (5%). Yeasts were the predominant organisms and were found in 100% of the samples. Geotrichum, Fusarium, and Penicillium spp. were the most prevalent molds in mung sprouts while Cladosporium and Penicillium spp. were most frequently found in ready-to-eat salad samples. According to results from the present study, effective control measures should be implemented to minimize the microbiological contamination of fresh produce sold in Tehran, Iran. PMID:25395902

  4. Degradation of a xanthene dye by Fe(II)-mediated activation of Oxone process.

    Science.gov (United States)

    Wang, Y R; Chu, W

    2011-02-28

    A powerful oxidation process using sulfate radicals activated by transition metal mediated Oxone process has been evaluated in depth by monitoring the degradation of a xanthene dye Rhodamine B (RhB) in aqueous solution. Ferrous ion was chosen as the transition metal due to its potential catalytic effect and wide availability in dyeing industrial effluent. The effects of parameters including reactant dosing sequence, Fe(II)/Oxone molar ratio and concentration, solution pH, and inorganic salts on the process performance have been investigated. Total RhB removal was obtained within 90 min under an optimal Fe(II)/Oxone molar ratio of 1:1. The RhB degradation was found to be a two-stage kinetics, consisting of a rapid initial decay and followed by a retarded stage. Additionally, experimental results indicated that the presence of certain anions had either a positive or negative effect on the process. The inhibitory effect in the presence of SO(4)(2-) was elucidated by a proposed formula using Nernst equation. Furthermore, dye mineralization in terms of TOC removal indicates that stepwise addition of Fe(II) and Oxone can significantly improve the process performance by about 20%, and the retention time required can be greatly reduced comparing with the conventional one-off dosing method. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. The Study of Microbial Environmental Processes Related to the Natural Attenuation of Uranium at the Rifle Site using Systems-level Biology

    Energy Technology Data Exchange (ETDEWEB)

    Methe, Barbara [J. Craig Venter Inst. (JCVI), Rockville, MD (United States); Lipton, Mary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mahadevan, Krishna [Univ. of Toronto, ON (Canada)

    2016-08-31

    Microbes exist in communities in the environment where they are fundamental drivers of global carbon, nutrient and metal cycles. In subsurface environments, they possess significant metabolic potential to affect these global cycles including the transformation of radionuclides. This study examined the influence of microbial communities in sediment zones undergoing biogeochemical cycling of carbon, nutrients and metals including natural attenuation of uranium. This study examined the relationship of both the microbiota (taxonomy) and their metabolic capacity (function) in driving carbon, nutrient and metal cycles including uranium reduction at the Department of Energy (DOE) Rifle Integrated Field Research Challenge (RIFRC). Objectives of this project were: 1) to apply systems-level biology through application of ‘metaomics’ approaches (collective analyses of whole microbial community DNA, RNA and protein) to the study of microbial environmental processes and their relationship to C, N and metals including the influence of microbial communities on uranium contaminant mobility in subsurface settings undergoing natural attenuation, 2) improve methodologies for data generation using metaomics (collectively metagenomics, metatranscriptomics and proteomics) technologies and analysis and interpretation of that data and 3) use the data generated from these studies towards microbial community-scale metabolic modeling. The strategy for examining these subsurface microbial communities was to generate sequence reads from microbial community DNA (metagenomics or whole genome shotgun sequencing (WGS)) and RNA (metatranscriptomcs or RNAseq) and protein information using proteomics. Results were analyzed independently and through computational modeling. Overall, the community model generated information on the microbial community structure that was observed using metaomic approaches at RIFRC sites and thus provides an important framework for continued community modeling

  6. Models of microbiome evolution incorporating host and microbial selection.

    Science.gov (United States)

    Zeng, Qinglong; Wu, Steven; Sukumaran, Jeet; Rodrigo, Allen

    2017-09-25

    parental contribution, when host-mediated selection acts on microbes concomitantly. We present a computational framework that integrates different selective processes acting on the evolution of microbiomes. Our framework demonstrates that selection acting on microbes can have a strong effect on microbial diversities and fitnesses, whereas selection on hosts can have weaker outcomes.

  7. Changing Feeding Regimes To Demonstrate Flexible Biogas Production: Effects on Process Performance, Microbial Community Structure, and Methanogenesis Pathways

    Science.gov (United States)

    Mulat, Daniel Girma; Jacobi, H. Fabian; Feilberg, Anders; Adamsen, Anders Peter S.; Richnow, Hans-Hermann

    2015-01-01

    Flexible biogas production that adapts biogas output to energy demand can be regulated by changing feeding regimes. In this study, the effect of changes in feeding intervals on process performance, microbial community structure, and the methanogenesis pathway was investigated. Three different feeding regimes (once daily, every second day, and every 2 h) at the same organic loading rate were studied in continuously stirred tank reactors treating distiller's dried grains with solubles. A larger amount of biogas was produced after feeding in the reactors fed less frequently (once per day and every second day), whereas the amount remained constant in the reactor fed more frequently (every 2 h), indicating the suitability of the former for the flexible production of biogas. Compared to the conventional more frequent feeding regimes, a methane yield that was up to 14% higher and an improved stability of the process against organic overloading were achieved by employing less frequent feeding regimes. The community structures of bacteria and methanogenic archaea were monitored by terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA and mcrA genes, respectively. The results showed that the composition of the bacterial community varied under the different feeding regimes, and the observed T-RFLP patterns were best explained by the differences in the total ammonia nitrogen concentrations, H2 levels, and pH values. However, the methanogenic community remained stable under all feeding regimes, with the dominance of the Methanosarcina genus followed by that of the Methanobacterium genus. Stable isotope analysis showed that the average amount of methane produced during each feeding event by acetoclastic and hydrogenotrophic methanogenesis was not influenced by the three different feeding regimes. PMID:26497462

  8. Changing Feeding Regimes To Demonstrate Flexible Biogas Production: Effects on Process Performance, Microbial Community Structure, and Methanogenesis Pathways.

    Science.gov (United States)

    Mulat, Daniel Girma; Jacobi, H Fabian; Feilberg, Anders; Adamsen, Anders Peter S; Richnow, Hans-Hermann; Nikolausz, Marcell

    2016-01-15

    Flexible biogas production that adapts biogas output to energy demand can be regulated by changing feeding regimes. In this study, the effect of changes in feeding intervals on process performance, microbial community structure, and the methanogenesis pathway was investigated. Three different feeding regimes (once daily, every second day, and every 2 h) at the same organic loading rate were studied in continuously stirred tank reactors treating distiller's dried grains with solubles. A larger amount of biogas was produced after feeding in the reactors fed less frequently (once per day and every second day), whereas the amount remained constant in the reactor fed more frequently (every 2 h), indicating the suitability of the former for the flexible production of biogas. Compared to the conventional more frequent feeding regimes, a methane yield that was up to 14% higher and an improved stability of the process against organic overloading were achieved by employing less frequent feeding regimes. The community structures of bacteria and methanogenic archaea were monitored by terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA and mcrA genes, respectively. The results showed that the composition of the bacterial community varied under the different feeding regimes, and the observed T-RFLP patterns were best explained by the differences in the total ammonia nitrogen concentrations, H2 levels, and pH values. However, the methanogenic community remained stable under all feeding regimes, with the dominance of the Methanosarcina genus followed by that of the Methanobacterium genus. Stable isotope analysis showed that the average amount of methane produced during each feeding event by acetoclastic and hydrogenotrophic methanogenesis was not influenced by the three different feeding regimes. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  9. Evaluation of microbial diversity in the pilot-scale beer brewing process by culture-dependent and culture-independent method.

    Science.gov (United States)

    Takahashi, M; Kita, Y; Kusaka, K; Mizuno, A; Goto-Yamamoto, N

    2015-02-01

    In the brewing industry, microbial management is very important for stabilizing the quality of the product. We investigated the detailed microbial community of beer during fermentation and maturation, to manage beer microbiology in more detail. We brewed a beer (all-malt) and two beerlike beverages (half- and low-malt) in pilot-scale fermentation and investigated the microbial community of them using a next-generation sequencer (454 GS FLX titanium), quantitative PCR, flow cytometry and a culture-dependent method. From 28 to 88 genera of bacteria and from 9 to 38 genera of eukaryotic micro-organisms were detected in each sample. Almost all micro-organisms died out during the boiling process. However, bacteria belonging to the genera Acidovorax, Bacillus, Brevundimonas, Caulobacter, Chryseobacterium, Methylobacterium, Paenibacillus, Polaromonas, Pseudomonas, Ralstonia, Sphingomonas, Stenotrophomonas, Tepidimonas and Tissierella were detected at the early and middle stage of fermentation, even though their cell densities were low (below approx. 10(3) cells ml(-1) ) and they were not almost detected at the end of fermentation. We revealed that the microbial community of beer during fermentation and maturation is very diverse and several bacteria possibly survive during fermentation. In this study, we revealed the detailed microbial communities of beer using next-generation sequencing. Some of the micro-organisms detected in this study were found in beer brewing process for the first time. Additionally, the possibility of growth of several bacteria at the early and middle stage of fermentation was suggested. © 2014 The Society for Applied Microbiology.

  10. Microbial mitigation-exacerbation continuum: a novel framework for microbiome effects on hosts in the face of stress.

    Science.gov (United States)

    David, Aaron S; Thapa-Magar, Khum B; Afkhami, Michelle E

    2018-03-01

    A key challenge to understanding microbiomes and their role in ecological processes is contextualizing their effects on host organisms, particularly when faced with environmental stress. One influential theory, the Stress Gradient Hypothesis, might predict that the frequency of positive interactions increases with stressful conditions such that microbial taxa would mitigate harmful effects on host performance. Yet, equally plausible is that microbial taxa could exacerbate these effects. Here, we introduce the Mitigation-Exacerbation Continuum as a novel framework to conceptualize microbial mediation of stress. We (1) use this continuum to quantify microbial mediation of stress for six plant species and (2) test the association between these continuum values and natural species' abundance. We factorially manipulated a common stress (allelopathy) and the presence of soil microbes to quantify microbial effects in benign and stressed environments for two critical early life-history metrics, seed germination and seedling biomass. Although we found evidence of both mitigation and exacerbation among the six species, exacerbation was more common. Across species, the degree of microbial-mediated effects on germination explained >80% of the variation of natural field abundances. Our results suggest a critical role of soil microbes in mediating plant stress responses, and a potential microbial mechanism underlying species abundance. © 2018 by the Ecological Society of America.

  11. Cannabis-Related Problems and Social Anxiety: The Mediational Role of Post-Event Processing.

    Science.gov (United States)

    Ecker, Anthony H; Buckner, Julia D

    2018-01-02

    Cannabis is the most commonly used illicit drug in the US, and is associated with a range of psychological, social, and physical health-related problems. Individuals who endorse elevated levels of social anxiety are especially at risk for experiencing cannabis-related problems, including cannabis use disorder, despite not using cannabis more often than those with more normative social anxiety. Identification of mechanisms that underlie the relationship between social anxiety and cannabis-related problems may inform treatment and prevention efforts. Post-event processing (PEP, i.e., cognitively reviewing past social interactions/performances) is a social anxiety-related phenomenon that may be one such mechanism. The current study sought to test PEP as a mediator of the relationship between social anxiety and cannabis-related problems, adjusting for cannabis use frequency. Cannabis-using (past 3-month) undergraduate students recruited in 2015 (N = 244; 76.2% female; 74.2% Non-Hispanic Caucasian) completed an online survey of cannabis use, cannabis-related problems, social anxiety, and PEP. Bootstrap estimate of the indirect effect of social anxiety through PEP was significant, suggesting PEP is a mediator of the social anxiety-cannabis-related problems relationship. Conclusions/Importance: Treatment and prevention efforts may benefit from targeting PEP among individuals with elevated social anxiety and cannabis-related problems.

  12. The Ku80 carboxy terminus stimulates joining and artemis-mediated processing of DNA ends.

    Science.gov (United States)

    Weterings, Eric; Verkaik, Nicole S; Keijzers, Guido; Florea, Bogdan I; Wang, Shih-Ya; Ortega, Laura G; Uematsu, Naoya; Chen, David J; van Gent, Dik C

    2009-03-01

    Repair of DNA double-strand breaks (DSBs) is predominantly mediated by nonhomologous end joining (NHEJ) in mammalian cells. NHEJ requires binding of the Ku70-Ku80 heterodimer (Ku70/80) to the DNA ends and subsequent recruitment of the DNA-dependent protein kinase catalytic subunit (DNA-PK(CS)) and the XRCC4/ligase IV complex. Activation of the DNA-PK(CS) serine/threonine kinase requires an interaction with Ku70/80 and is essential for NHEJ-mediated DSB repair. In contrast to previous models, we found that the carboxy terminus of Ku80 is not absolutely required for the recruitment and activation of DNA-PK(CS) at DSBs, although cells that harbored a carboxy-terminal deletion in the Ku80 gene were sensitive to ionizing radiation and showed reduced end-joining capacity. More detailed analysis of this repair defect showed that DNA-PK(CS) autophosphorylation at Thr2647 was diminished, while Ser2056 was phosphorylated to normal levels. This resulted in severely reduced levels of Artemis nuclease activity in vivo and in vitro. We therefore conclude that the Ku80 carboxy terminus is important to support DNA-PK(CS) autophosphorylation at specific sites, which facilitates DNA end processing by the Artemis endonuclease and the subsequent joining reaction.

  13. The Ku80 Carboxy Terminus Stimulates Joining and Artemis-Mediated Processing of DNA Ends▿

    Science.gov (United States)

    Weterings, Eric; Verkaik, Nicole S.; Keijzers, Guido; Florea, Bogdan I.; Wang, Shih-Ya; Ortega, Laura G.; Uematsu, Naoya; Chen, David J.; van Gent, Dik C.

    2009-01-01

    Repair of DNA double-strand breaks (DSBs) is predominantly mediated by nonhomologous end joining (NHEJ) in mammalian cells. NHEJ requires binding of the Ku70-Ku80 heterodimer (Ku70/80) to the DNA ends and subsequent recruitment of the DNA-dependent protein kinase catalytic subunit (DNA-PKCS) and the XRCC4/ligase IV complex. Activation of the DNA-PKCS serine/threonine kinase requires an interaction with Ku70/80 and is essential for NHEJ-mediated DSB repair. In contrast to previous models, we found that the carboxy terminus of Ku80 is not absolutely required for the recruitment and activation of DNA-PKCS at DSBs, although cells that harbored a carboxy-terminal deletion in the Ku80 gene were sensitive to ionizing radiation and showed reduced end-joining capacity. More detailed analysis of this repair defect showed that DNA-PKCS autophosphorylation at Thr2647 was diminished, while Ser2056 was phosphorylated to normal levels. This resulted in severely reduced levels of Artemis nuclease activity in vivo and in vitro. We therefore conclude that the Ku80 carboxy terminus is important to support DNA-PKCS autophosphorylation at specific sites, which facilitates DNA end processing by the Artemis endonuclease and the subsequent joining reaction. PMID:19103741