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Sample records for factors controlling microbial

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

    OpenAIRE

    Anthony G. Fane; Bing Wu

    2012-01-01

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

  2. Key factors controlling microbial community response after a fire: importance of severity and recurrence

    Science.gov (United States)

    Lombao, Alba; Barreiro, Ana; Martín, Ángela; Díaz-Raviña, Montserrat

    2015-04-01

    Microorganisms play an important role in forest ecosystems, especially after fire when vegetation is destroyed and soil is bared. Fire severity and recurrence might be one of main factors controlling the microbial response after a wildfire but information about this topic is scarce. The aim of this study is to evaluate the influence of fire regimen (recurrence and severity) on soil microbial community structure by means of the analysis of phospholipid fatty acid (PLFA). The study was performed with unburned and burned samples collected from the top layer of a soil affected by a high severity fire (Laza, NW Spain) heated under laboratory conditions at different temperatures (50°C, 75°C, 100°C, 125°C, 150°C, 175°C, 200°C, 300°C) to simulate different fire intensities; the process was repeated after further soil recovery (1 month incubation) to simulate fire recurrence. The soil temperature was measured with thermocouples and used to calculate the degree-hours as estimation of the amount of heat supplied to the samples (fire severity). The PLFA analysis was used to estimate total biomass and the biomass of specific groups (bacteria, fungi, gram-positive bacteria and gram-negative bacteria) as well as microbial community structure (PLFA pattern) and PLFA data were analyzed by means of principal component analysis (PCA) in order to identify main factors determining microbial community structure. The results of PCA, performed with the whole PLFA data set, showed that first component explained 35% of variation and clearly allow us to differentiate unburned samples from the corresponding burned samples, while the second component, explaining 16% of variation, separated samples according the heating temperature. A marked impact of fire regimen on soil microorganisms was detected; the microbial community response varied depending on previous history of soil heating and the magnitude of changes in the PLFA pattern was related to the amount of heat supplied to the

  3. [Risk factors for contact lens-related microbial keratitis: A multicenter case-control study].

    Science.gov (United States)

    Becmeur, P H; Abry, F; Bourcier, T; Meyer, N; Sauer, A

    2017-03-01

    Currently, the most feared complication by ophthalmologists of contact lens (CL) wear is microbial keratitis (MK), even though its incidence remains low. It is also a significant financial burden for society. This study aimed to identify the risk factors for CL-related MK especially with regard to hygiene and pattern of use, in a large, prospective, multicenter, case-control study. A multicenter retrospective case-control study was designed. The CL-related MK subpopulation (case) was compared with healthy CL wearers (control) using a 52-item anonymous questionnaire designed to determine subject demographics, lens wear history, lens type and disinfection solution, fitting, patient education, hygiene and maintenance of contact lenses, and patient history. Univariate logistic regression analysis was performed to compare both groups. The study included 497 cases and 364 controls. The risk factors associated with the greatest increased odds of CL-related MK were as follows: extended wear (OR=2.96 [1.65-5.33], Pcase replacement (OR=3.95 [2.28-6.82] Pcase maintenance. The knowledge of these risks factors incentivizes action at all levels to reduce the incidence of MK, from the prescriber to the patient, including the type of CL, case and contact lens solution. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  4. Factors controlling short-term soil microbial response after laboratory heating. Preliminary results

    Science.gov (United States)

    Jiménez-Compán, Elizabeth; Jiménez-Morillo, Nicasio; Jordán, Antonio; Bárcenas-Moreno, Gema

    2015-04-01

    Soil microbial response after fire is controlled by numerous variables which conclude with a mosaic of results depending on organic carbon alterations or pH fire-induced changes. This fact has complicated the studies focused on post-fire microbial response, compiling high variability of opposite result in the bibliography. Soil laboratory heating cannot emulate a real wildfire effect on soil but lead us the possibility to control several variables and it is a valid tool to clarify the relative weight of different factors controlling microbial response after soil heating. In this preliminary study different heated treatments were applied to unaltered forest soil samples, obtaining 4 different heating treatments to simulate a range of fire intensities: unaltered-control (UH), and soil heated at 300, 450 and 500 °C. In order to isolate possible nutrient availability or pH heating-induced changes, different culture media were prepared using soil:water extract from each heating treatments and adding different supplements to obtain the total of 11 different culture media: unheated soil without supplements (UH-N-), unheated soil with nutrient supplement (UH-N+), soil heated at 300 °C without supplements (300-N-), soil heated at 300 °C with nutrient supplement (300-N+), soil heated at 300 °C with nutrient supplement and pH-buffered (300-N+pH); soil heated at 450 °C without supplements (450-N-), soil heated at 450 °C with nutrient supplement (450-N+), soil heated at 450 °C with nutrient supplement and pH-buffered (450-N+); soil heated at 500 °C without supplements (500-N-), soil heated at 500 °C with nutrient supplement (500-N+), soil heated at 500 °C with nutrient supplement and pH-buffered (500-N+). Each media was inoculated with different dilutions of a microbial suspension from the original unaltered soil, and the abundance of viable and cultivable microorganisms were measured by plate count method. In addition, the analysis of heating-induced soil organic

  5. Fine scale spatial variability of microbial pesticide degradation in soil: scales, controlling factors, and implications

    Directory of Open Access Journals (Sweden)

    Arnaud eDechesne

    2014-12-01

    Full Text Available Pesticide biodegradation is a soil microbial function of critical importance for modern agriculture and its environmental impact. While it was once assumed that this activity was homogeneously distributed at the field scale, mounting evidence indicates that this is rarely the case. Here, we critically examine the literature on spatial variability of pesticide biodegradation in agricultural soil. We discuss the motivations, methods, and main findings of the primary literature. We found significant diversity in the approaches used to describe and quantify spatial heterogeneity, which complicates inter-studies comparisons. However, it is clear that the presence and activity of pesticide degraders is often highly spatially variable with coefficients of variation often exceeding 50% and frequently displays nonrandom spatial patterns. A few controlling factors have tentatively been identified across pesticide classes: they include some soil characteristics (pH and some agricultural management practices (pesticide application, tillage, while other potential controlling factors have more conflicting effects depending on the site or the pesticide. Evidence demonstrating the importance of spatial heterogeneity on the fate of pesticides in soil has been difficult to obtain but modelling and experimental systems that do not include soil’s full complexity reveal that this heterogeneity must be considered to improve prediction of pesticide biodegradation rates or of leaching risks. Overall, studying the spatial heterogeneity of pesticide biodegradation is a relatively new field at the interface of agronomy, microbial ecology, and geosciences and a wealth of novel data is being collected from these different disciplinary perspectives. We make suggestions on possible avenues to take full advantage of these investigations for a better understanding and prediction of the fate of pesticides in soil.

  6. New microbial growth factor

    Science.gov (United States)

    Bok, S. H.; Casida, L. E., Jr.

    1977-01-01

    A screening procedure was used to isolate from soil a Penicillium sp., two bacterial isolates, and a Streptomyces sp. that produced a previously unknown microbial growth factor. This factor was an absolute growth requirement for three soil bacteria. The Penicillium sp. and one of the bacteria requiring the factor, an Arthrobacter sp., were selected for more extensive study concerning the production and characteristics of the growth factor. It did not seem to be related to the siderochromes. It was not present in soil extract, rumen fluid, or any other medium component tested. It appears to be a glycoprotein of high molecular weight and has high specific activity. When added to the diets for a meadow-vole mammalian test system, it caused an increased consumption of diet without a concurrent increase in rate of weight gain.

  7. Microbial processes and factors controlling their activities in alkaline lakes of the Mongolian plateau

    Science.gov (United States)

    Namsaraev, Zorigto B.; Zaitseva, Svetlana V.; Gorlenko, Vladimir M.; Kozyreva, Ludmila P.; Namsaraev, Bair B.

    2015-11-01

    A striking feature of the Mongolian plateau is the wide range of air temperatures during a year, -30 to 30°C. High summer temperatures, atmospheric weathering and the arid climate lead to formation of numerous alkaline soda lakes that are covered by ice during 6-7 months per year. During the study period, the lakes had pH values between 8.1 to 10.4 and salinity between 1.8 and 360 g/L. According to chemical composition, the lakes belong to sodium carbonate, sodium chloride-carbonate and sodium sulfate-carbonate types. This paper presents the data on the water chemical composition, results of the determination of the rates of microbial processes in microbial mats and sediments in the lakes studied, and the results of a Principal Component Analysis of environmental variables and microbial activity data. Temperature was the most important factor that influenced both chemical composition and microbial activity. pH and salinity are also important factors for the microbial processes. Dark CO2 fixation is impacted mostly by salinity and the chemical composition of the lake water. Total photosynthesis and sulfate-reduction are impacted mostly by pH. Photosynthesis is the dominant process of primary production, but the highest rate (386 mg C/(L•d)) determined in the lakes studied were 2-3 times lower than in microbial mats of lakes located in tropical zones. This can be explained by the relatively short warm period that lasts only 3-4 months per year. The highest measured rate of dark CO2 assimilation (59.8 mg C/(L•d)) was much lower than photosynthesis. The highest rate of sulfate reduction was 60 mg S/(L•d), while that of methanogenesis was 75.6 μL CN4/(L•d) in the alkaline lakes of Mongolian plateau. The rate of organic matter consumption during sulfate reduction was 3-4 orders of magnitude higher than that associated with methanogenesis.

  8. Fine scale spatial variability of microbial pesticide degradation in soil: scales, controlling factors, and implications

    DEFF Research Database (Denmark)

    Dechesne, Arnaud; Badawi, N.; Aamand, Jens;

    2014-01-01

    Pesticide biodegradation is a soil microbial function of critical importance for modern agriculture and its environmental impact. While it was once assumed that this activity was homogeneously distributed at the field scale, mounting evidence indicates that this is rarely the case. Here, we criti...

  9. Contrasting factors controlling microbial respiratory activity in the sediment of two adjacent Mediterranean wetlands.

    Science.gov (United States)

    de Vicente, Inmaculada; Amores, Victoria; Guerrero, Francisco; Cruz-Pizarro, Luis

    2010-07-01

    Electron transport system (ETS) activity of sediments as an indication of microbial metabolic activity was examined in two adjacent Mediterranean wetlands (southern Spain). We determined the spatio-temporal variation in ETS, and we explored the potential biological [organic matter (OM), chlorophyll a (Chl a), aerobic and anaerobic bacteria] drivers of sediment ETS activity. ETS activity was notably higher in the eutrophic Lake Nueva (34.91 microl O(2) g(-1) D.W. h(-1)) than in the hypertrophic Lake Honda (24.99 microl O(2) g(-1) D.W. h(-1)). Strong spatial differences were observed in ETS in both study sites. Highest ETS values were achieved at the surface sediment at the deepest sampling station in each lake and a notable reduction in ETS with sediment depth was observed. By using linear regression and multiple regression analysis, OM was identified as the best predictor of ETS in Lake Honda while Chl a was the best predictor in Lake Nueva. The strong influence of OM supply on ETS activity in sediment from Lake Honda was the consequence of the labile nature of sedimentary OM, while a more refractory OM (with a higher contribution of vascular plants) comprised most of the sedimentary OM from Lake Nueva. By contrast, a large contribution of phytobenthos (supported by a higher lake water transparency) to ETS has been recognized in sediments from Lake Nueva. In summary, the results of this study revealed that the relative importance of planktonic primary producers (phytoplankton), benthic algae and vascular plants in the study sites could explain the differences observed in the intensity of sediment ETS as well as in their drivers.

  10. Factors Controlling Soil Microbial Biomass and Bacterial Diversity and Community Composition in a Cold Desert Ecosystem: Role of Geographic Scale.

    Directory of Open Access Journals (Sweden)

    David J Van Horn

    Full Text Available Understanding controls over the distribution of soil bacteria is a fundamental step toward describing soil ecosystems, understanding their functional capabilities, and predicting their responses to environmental change. This study investigated the controls on the biomass, species richness, and community structure and composition of soil bacterial communities in the McMurdo Dry Valleys, Antarctica, at local and regional scales. The goals of the study were to describe the relationships between abiotic characteristics and soil bacteria in this unique, microbially dominated environment, and to test the scale dependence of these relationships in a low complexity ecosystem. Samples were collected from dry mineral soils associated with snow patches, which are a significant source of water in this desert environment, at six sites located in the major basins of the Taylor and Wright Valleys. Samples were analyzed for a suite of characteristics including soil moisture, pH, electrical conductivity, soil organic matter, major nutrients and ions, microbial biomass, 16 S rRNA gene richness, and bacterial community structure and composition. Snow patches created local biogeochemical gradients while inter-basin comparisons encompassed landscape scale gradients enabling comparisons of microbial controls at two distinct spatial scales. At the organic carbon rich, mesic, low elevation sites Acidobacteria and Actinobacteria were prevalent, while Firmicutes and Proteobacteria were dominant at the high elevation, low moisture and biomass sites. Microbial parameters were significantly related with soil water content and edaphic characteristics including soil pH, organic matter, and sulfate. However, the magnitude and even the direction of these relationships varied across basins and the application of mixed effects models revealed evidence of significant contextual effects at local and regional scales. The results highlight the importance of the geographic scale of

  11. Main factors controlling microbial community structure, growth and activity after reclamation of a tailing pond with aided phytostabilization

    Science.gov (United States)

    Zornoza, Raúl; Acosta, José A.; Martínez-Martínez, Silvia; Faz, Ángel; Bååth, Erland

    2015-04-01

    Reclamation on bare tailing ponds has the potential to represent soil genesis in Technosols favoring the understanding of the changes of microbial communities and function. In this study we used phytostabilization aided with calcium carbonate and pig slurry/manure to reclaim an acidic bare tailing pond with the aim of investigating the effect of amending and different species on microbial community structure and function. We sampled after two years of amending and planting: unamended tailing soil (UTS), non-rhizospheric amended tailing soil (ATS), rhizospheric soil from four species, and non-rhizospheric native forest soil (NS), which acted as reference. The application of amendments increased pH up to neutrality, organic carbon (Corg), C/N and aggregate stability, while decreased salinity and heavy metals availability. No effect of rhizosphere was observed on physicochemical properties, metals immobilization and microbial community structure and function. To account for confounding effects due to soil organic matter, microbial properties were expressed per Corg. The high increments in pH and Corg have been the main factors driving changes in microbial community structure and function. Bacterial biomass was higher in UTS, without significant differences among the rest of soils. Fungal biomass followed the trend UTS growth increased and fungal growth decreased with increasing pH, despite the high availability of metals at low pH. Enzyme activities were lower in UTS, being β-glucosidase and β-glucosaminidase activities highly correlated with bacterial growth. Microbial activities were not correlated with the exchangeable fraction of heavy metals, indicating that microbial function is not strongly affected by these metals, likely due to the efficiency of the reclamation procedure to reduce metals toxicity. Changes in microbial community composition were largely explained by changes in pH, heavy metals availability and Corg, with increments in fungal and

  12. Factors Controlling Soil Microbial Biomass and Bacterial Diversity and Community Composition in a Cold Desert Ecosystem: Role of Geographic Scale

    OpenAIRE

    Horn, David J. van; Lee Van Horn, M.; Barrett, John E.; Gooseff, Michael N.; Altrichter, Adam E; Geyer, Kevin M; Lydia H Zeglin; Takacs-Vesbach, Cristina D.

    2013-01-01

    Understanding controls over the distribution of soil bacteria is a fundamental step toward describing soil ecosystems, understanding their functional capabilities, and predicting their responses to environmental change. This study investigated the controls on the biomass, species richness, and community structure and composition of soil bacterial communities in the McMurdo Dry Valleys, Antarctica, at local and regional scales. The goals of the study were to describe the relationships between ...

  13. Hydrological controls on glacially exported microbial assemblages

    Science.gov (United States)

    Dubnick, Ashley; Kazemi, Sina; Sharp, Martin; Wadham, Jemma; Hawkings, Jon; Beaton, Alexander; Lanoil, Brian

    2017-05-01

    The Greenland Ice Sheet (GrIS) exports approximately 400 km3 of freshwater annually to downstream freshwater and marine ecosystems. These meltwaters originate in a wide range of well-defined habitats that can be associated with very different physical environments within the ice sheet, ranging from oxygenated surface environments that are exposed to light and supplied with nutrients from atmospheric/aeolian sources to subglacial environments that are permanently dark, isolated from the atmosphere, and potentially anoxic. Hydrological conditions in the latter likely favor prolonged rock-water contact. The seasonally evolving hydrological system that drains meltwaters from the GrIS connects these distinct microbial habitats and exports the microbes contained within them to downstream ecosystems. The microbial assemblages exported in glacier meltwater may have an impact on downstream ecosystem function and development. We explored how the seasonal development of a glacial drainage system influences the character of microbial assemblages exported from the GrIS by monitoring the seasonal changes in hydrology, water chemistry, and microbial assemblage composition of meltwaters draining from a glacier in southwest Greenland. We found that the microbial assemblages exported in meltwaters varied in response to glacier hydrological flow path characteristics. Whether or not meltwaters passed through the subglacial environment was the first-order control on the composition of the microbial assemblages exported from the glacier, while water source (i.e., supraglacial or extraglacial) and subglacial residence times were second-order controls. Glacier hydrology therefore plays a fundamental role in determining the microbial exports from glaciated watersheds.

  14. Advances in microbial insect control in horticultural ecosystems

    Science.gov (United States)

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

  15. Microbial control of arthropod pests of orchards in temperate climates

    Science.gov (United States)

    Temperate orchards systems have several environmental features that make them conducive to microbial control strategies including adequate soil moisture, shading (protection from harmful UV) and stability. This chapter reviews and analyzes microbial control efforts in temperate orchards, including p...

  16. Microbial control over carbon cycling in soil

    Directory of Open Access Journals (Sweden)

    Joshua eSchimel

    2012-09-01

    Full Text Available A major thrust of terrestrial microbial ecology is focused on understanding when and how the composition of the microbial community affects the functioning of biogeochemical processes at the ecosystem scale (meters-to-kilometers and days-to-years. While research has demonstrated these linkages for physiologically and phylogenetically narrow processes such as trace gas emissions and nitrification, there is less conclusive evidence that microbial community composition influences the broad processes of decomposition and organic matter turnover in soil. In this paper, we consider how soil microbial community structure influences C-cycling. We consider the phylogenetic level at which microbes form meaningful guilds, based on overall life history strategies, and suggest that these are associated with deep evolutionary divergences, while much of the species-level diversity probably reflects functional redundancy. We then consider under what conditions it is possible for differences among microbes to affect process dynamics, and argue that while microbial community structure may be important in the rate of OM breakdown in the rhizosphere and in detritus, it is likely not important in the mineral soil. In mineral soil, physical access to occluded or sorbed substrates is the rate-limiting process. Microbial community influences on OM turnover in mineral soils are based on how organisms allocate the C they take up—not only do the fates of the molecules differ, but they can affect the soil system differently as well. For example, extracellular enzymes and extracellular polysaccharides can be key controls on soil structure and function. How microbes allocate C may also be particularly important for understanding the long-term fate of C in soil—is it sequestered or not?

  17. Engineering microbial consortia for controllable outputs

    Energy Technology Data Exchange (ETDEWEB)

    Lindemann, Stephen R.; Bernstein, Hans C.; Song, Hyun-Seob; Fredrickson, Jim K.; Fields, Matthew W.; Shou, Wenying; Johnson, David R.; Beliaev, Alexander S.

    2016-03-11

    Much research has been invested into engineering microorganisms to perform desired biotransformations; nonetheless, these efforts frequently fall short of expected results due to the unforeseen effects of biofeedback regulation and functional incompatibility. In nature, metabolic function is compartmentalized into diverse organisms assembled into resilient consortia, in which the division of labor is thought to lead to increased community efficiency and productivity. Here, we consider whether and how consortia can be designed to perform bioprocesses of interest beyond the metabolic flexibility limitations of a single organism. Advances in post-genomic analysis of microbial consortia and application of high-resolution global measurements now offer the promise of systems-level understanding of how microbial consortia adapt to changes in environmental variables and inputs of carbon and energy. We argue that when combined with appropriate modeling framework that predictive knowledge generates testable hypotheses and orthogonal synthetic biology tools, such understanding can dramatically improve our ability to control the fate and functioning of consortia. In this article, we articulate our collective perspective on the current and future state of microbial community engineering and control while placing specific emphasis on ecological principles that promote control over community function and emergent properties.

  18. Microbial control of arthropod-borne disease

    Science.gov (United States)

    Saldaña, Miguel A; Hegde, Shivanand; Hughes, Grant L

    2017-01-01

    Arthropods harbor a diverse array of microbes that profoundly influence many aspects of host biology, including vector competence. Additionally, symbionts can be engineered to produce molecules that inhibit pathogens. Due to their intimate association with the host, microbes have developed strategies that facilitate their transmission, either horizontally or vertically, to conspecifics. These attributes make microbes attractive agents for applied strategies to control arthropod-borne disease. Here we discuss the recent advances in microbial control approaches to reduce the burden of pathogens such as Zika, Dengue and Chikungunya viruses, and Trypanosome and Plasmodium parasites. We also highlight where further investigation is warranted. PMID:28177042

  19. Microbial control of arthropod-borne disease

    Directory of Open Access Journals (Sweden)

    Miguel A Saldaña

    Full Text Available Arthropods harbor a diverse array of microbes that profoundly influence many aspects of host biology, including vector competence. Additionally, symbionts can be engineered to produce molecules that inhibit pathogens. Due to their intimate association with the host, microbes have developed strategies that facilitate their transmission, either horizontally or vertically, to conspecifics. These attributes make microbes attractive agents for applied strategies to control arthropod-borne disease. Here we discuss the recent advances in microbial control approaches to reduce the burden of pathogens such as Zika, Dengue and Chikungunya viruses, and Trypanosome and Plasmodium parasites. We also highlight where further investigation is warranted.

  20. Microbial control by packaging: a review.

    Science.gov (United States)

    Cutter, Catherine Nettles

    2002-03-01

    Since early man first used a variety of natural containers to store and eat foods, significant developments in food packaging materials have provided the means to suppress microbial growth as well as protect foods from external microbial contamination. Throughout this progression, packaging materials have been developed specifically to prevent the deterioration of foods resulting from exposure to air, moisture, or pH changes associated with the food or the surrounding atmosphere. Both flexible and rigid packaging materials, alone or in combination with other preservation methods, have been developed to offer the necessary barrier, inactivation, and containment properties required for successful food packaging. Examples of flexible packaging used to inactivate microorganisms associated with foods include controlled atmosphere, vacuum, modified atmosphere, active, and edible packaging. Additionally, the combination of rigid packaging materials made from metal, glass, or plastic with heat provides the most effective and widely used method for inactivating microorganisms. As with all food products, it is necessary to integrate a HACCP-based program to assure quality throughout the packaging operation. In addition to packaging improvements, other novel technologies include the development of detectors for oxygen levels, bacterial toxins, and microbial growth, or the integration of time-temperature indicators for detection of improper handling or storage.

  1. Microbial control of seawater by microfiltration

    Directory of Open Access Journals (Sweden)

    Wilmer Soler T

    2010-08-01

    Full Text Available Recent scientific literature presents seawater as a potential aid to solve a variety of health diseases in animals and human beings because by means of its mineral and trace elements content. In Colombia, Nicaragua and Spain it is collected in a natural way from de shore and drunk; however, this can represent a health risk because of the problems related to chemical and microbiological contamination. Microbial control of seawater allows the improvement of its microbiological quality. Objective: to compare the efficiency of three microbial control methods: microfiltration, solar exposition and quarantine. Methodology: 30 samples were collected in 20-liter high density polyethylene containers in three different places in the Colombian Atlantic coast. Results: 15 samples out of 30 showed the presence of bacteria such as E. coli and halophiles bacteria like Vibrio and Aeromonas. Microfiltration through ceramic filters of 0.5 µm produces disinfection in 100% of the samples but the quarantine for five months and solar disinfection are effective in 66 and 21% respectively. The latter requires certain weather conditions to achieve disinfection and it only allows managing small quantities of water. Dicussion: Considering chemical contamination in some places which cannot be controlled through disinfection methods, the collection of water offshore in clean places is suggested and then microfiltration treatment should be performed.

  2. Augmenting Plant Immune Responses and Biological Control by Microbial Determinants

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    Sang Moo Lee

    2015-09-01

    Full Text Available Plant have developed sophisticated defence mechanisms against microbial pathogens. The recent accumulated information allow us to understand the nature of plant immune responses followed by recognition of microbial factors/determinants through cutting-edge genomics and multi-omics techniques. However, the practical approaches to sustain plant health using enhancement of plant immunity is yet to be fully appreciated. Here, we overviewed the general concept and representative examples on the plant immunity. The fungal, bacterial, and viral determinants that was previously reported as the triggers of plant immune responses are introduced and described as the potential protocol of biological control. Specifically, the role of chitin, glucan, lipopolysaccharides/extracellular polysaccharides, microbe/pathogen-associated molecular pattern, antibiotics, mimic-phytohormones, N-acyl homoserine lactone, harpin, vitamins, and volatile organic compounds are considered. We hope that this review stimulates scientific community and farmers to broaden their knowledge on the microbial determinant-based biological control and to apply the technology on the integrated pest management program.

  3. Factors Affecting Microbial Contamination of Market Eggs: A Review

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    Svobodová J.

    2015-01-01

    Full Text Available The aim of the review was to analyze the ways of microbial contamination, the protective mechanism of egg, and factors that affect the quantity of contamination and microbial penetration. Eggs can be contaminated during their formation in the infected reproductive organs of hens or after laying, when eggs are exposed to contaminated environment. The eggs are equipped against microbial contamination by several protective mechanisms comprising the presence of cuticle, eggshell, eggshell membranes, occurrence of some antibacterial proteins, and high pH value of albumen. There are several factors that affect the quantity of microbial contamination and penetration such as species of bacteria, the amount of microorganisms, storage conditions, quality of eggshell or number of pores.

  4. Antimicrobial Materials for Advanced Microbial Control in Spacecraft Water Systems

    Science.gov (United States)

    Birmele, Michele; Caro, Janicce; Newsham, Gerard; Roberts, Michael; Morford, Megan; Wheeler, Ray

    2012-01-01

    Microbial detection, identification, and control are essential for the maintenance and preservation of spacecraft water systems. Requirements set by NASA put limitations on the energy, mass, materials, noise, cost, and crew time that can be devoted to microbial control. Efforts are being made to attain real-time detection and identification of microbial contamination in microgravity environments. Research for evaluating technologies for capability enhancement on-orbit is currently focused on the use of adenosine triphosphate (ATP) analysis for detection purposes and polymerase chain reaction (peR) for microbial identification. Additional research is being conducted on how to control for microbial contamination on a continual basis. Existing microbial control methods in spacecraft utilize iodine or ionic silver biocides, physical disinfection, and point-of-use sterilization filters. Although these methods are effective, they require re-dosing due to loss of efficacy, have low human toxicity thresholds, produce poor taste, and consume valuable mass and crew time. Thus, alternative methods for microbial control are needed. This project also explores ultraviolet light-emitting diodes (UV-LEDs), surface passivation methods for maintaining residual biocide levels, and several antimicrobial materials aimed at improving current microbial control techniques, as well as addressing other materials presently under analysis and future directions to be pursued.

  5. Effects of Some Dietary Factors on Ruminal Microbial Protein Synthesis

    OpenAIRE

    KARSLI, Mehmet Akif

    2001-01-01

    The effects of some dietary factors, other than source and amount of N and carbohydrate, on the amount and efficiency of microbial protein synthesis are discussed in this review. Specifically, these factors include dry matter intake of animals, forage:concentrate ratio of diets, rate of N and carbohydrate degradation, synchronized release of N and energy from diets, rate of passage, and other factors, such as vitamins and minerals. It seemed that diets containing a mixture of forages and conc...

  6. Soil microbial structure and function post-volcanic eruption on Kasatochi Island and regional controls on microbial heterogeneity

    Science.gov (United States)

    Zeglin, L. H.; Rainey, F.; Wang, B.; Waythomas, C.; Talbot, S. L.

    2013-12-01

    Microorganisms are abundant and diverse in soil and their integrated activity drives nutrient cycling on the ecosystem scale. Organic matter (OM) inputs from plant production support microbial heterotrophic life, and soil geochemistry constrains microbial activity and diversity. As vegetation and soil develops over time, these factors change, modifying the controls on microbial heterogeneity. Following a volcanic eruption, ash deposition creates new surfaces where both organismal growth and weathering processes are effectively reset. The trajectory of microbial community development following this disturbance depends on both organic matter accumulation and geochemical constraints. Also, dispersal of microbial cells to the sterile ash surface may determine microbial community succession. The Aleutian Islands (Alaska, USA) are a dynamic volcanic region, with active and dormant volcanoes distributed across the volcanic arc. One of these volcanoes, Kasatochi, erupted violently in August 2008, burying a small lush island in pryoclastic flows and fine ash. Since, plants and birds are beginning to re-establish on developing surfaces, including legacy soils exposed by rapid erosion of pyroclastic deposits, suggesting that recovery of microbial life is also proceeding. However, soil microbial diversity and function has not been examined on Kasatochi Island or across the greater Aleutian region. The project goal is to address these questions: How is soil microbial community structure and function developing following the Kasatochi eruption? What is the relative importance of dispersal, soil OM and geochemistry to microbial community heterogeneity across the Aleutians? Surface mineral soil (20-cm depth) samples were collected from Kasatochi Island in summer 2013, five years after the 2008 eruption, and from eight additional Aleutian islands. On Kasatochi, pryoclastic deposits, exposed legacy soils supporting regrowth of remnant dune wild-rye (Leymus mollis) and mesic meadow

  7. Microbial control of arthropod pests of tropical tree fruits.

    Science.gov (United States)

    Dolinski, Claudia; Lacey, Lawrence A

    2007-01-01

    A multitude of insects and mites attack fruit crops throughout the tropics. The traditional method for controlling most of these pests is the application of chemical pesticides. Growing concern on the negative environmental effects has encouraged the development of alternatives. Inundatively and inoculatively applied microbial control agents (virus, bacteria, fungi, and entomopathogenic nematodes) have been developed as alternative control methods of a wide variety of arthropods including tropical fruit pests. The majority of the research and applications in tropical fruit agroecosystems has been conducted in citrus, banana, coconut, and mango. Successful microbial control initiatives of citrus pests and mites have been reported. Microbial control of arthropod pests of banana includes banana weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae) (with EPNs and fungi) among others Oryctes rhinoceros (L.) is one of the most important pests of coconut and one of the most successful uses of non-occluded virus for classical biological control. Key pests of mango that have been controlled with microbial control agents include fruit flies (Diptera: Tephritidae) (with EPNs and fungi), and other pests. Also successful is the microbial control of arthropod pests of guava, papaya and pineapple. The challenge towards a broader application of entomopathogens is the development of successful combinations of entomopathogens, predators, and parasitoids along with other interventions to produce effective and sustainable pest management.

  8. Intestinal microbial ecology and environmental factors affecting necrotizing enterocolitis.

    Directory of Open Access Journals (Sweden)

    Roberto Murgas Torrazza

    Full Text Available Necrotizing enterocolitis (NEC is the most devastating intestinal disease affecting preterm infants. In addition to being associated with short term mortality and morbidity, survivors are left with significant long term sequelae. The cost of caring for these infants is high. Epidemiologic evidence suggests that use of antibiotics and type of feeding may cause an intestinal dysbiosis important in the pathogenesis of NEC, but the contribution of specific infectious agents is poorly understood. Fecal samples from preterm infants ≤ 32 weeks gestation were analyzed using 16S rRNA based methods at 2, 1, and 0 weeks, prior to diagnosis of NEC in 18 NEC cases and 35 controls. Environmental factors such as antibiotic usage, feeding type (human milk versus formula and location of neonatal intensive care unit (NICU were also evaluated. Microbiota composition differed between the three neonatal units where we observed differences in antibiotic usage. In NEC cases we observed a higher proportion of Proteobacteria (61% two weeks and of Actinobacteria (3% 1 week before diagnosis of NEC compared to controls (19% and 0.4%, respectively and lower numbers of Bifidobacteria counts and Bacteroidetes proportions in the weeks before NEC diagnosis. In the first fecal samples obtained during week one of life we detected a novel signature sequence, distinct from but matching closest to Klebsiella pneumoniae, that was strongly associated with NEC development later in life. Infants who develop NEC exhibit a different pattern of microbial colonization compared to controls. Antibiotic usage correlated with these differences and combined with type of feeding likely plays a critical role in the development of NEC.

  9. Modulation of tumor necrosis factor by microbial pathogens.

    OpenAIRE

    Rahman, Masmudur M.; Grant McFadden

    2006-01-01

    In response to invasion by microbial pathogens, host defense mechanisms get activated by both the innate and adaptive arms of the immune responses. TNF (tumor necrosis factor) is a potent proinflammatory cytokine expressed by activated macrophages and lymphocytes that induces diverse cellular responses that can vary from apoptosis to the expression of genes involved in both early inflammatory and acquired immune responses. A wide spectrum of microbes has acquired elegant mechanisms to overcom...

  10. Microbial colonization and controls in dryland systems

    Science.gov (United States)

    Pointing, Stephen B.; Belnap, Jayne

    2012-01-01

    Drylands constitute the most extensive terrestrial biome, covering more than one-third of the Earth's continental surface. In these environments, stress limits animal and plant life, so life forms that can survive desiccation and then resume growth following subsequent wetting assume the foremost role in ecosystem processes. In this Review, we describe how these organisms assemble in unique soil- and rock-surface communities to form a thin veneer of mostly microbial biomass across hot and cold deserts. These communities mediate inputs and outputs of gases, nutrients and water from desert surfaces, as well as regulating weathering, soil stability, and hydrological and nutrient cycles. The magnitude of regional and global desert-related environmental impacts is affected by these surface communities; here, we also discuss the challenges for incorporating the consideration of these communities and their effects into the management of dryland resources.

  11. T lymphocytes control microbial composition by regulating the abundance of Vibrio in the zebrafish gut

    NARCIS (Netherlands)

    Brugman, S.; Schneeberger, K.; Witte, M.; Klein, M.R.

    2014-01-01

    Dysbiosis of the intestinal microbial community is considered a risk factor for development of chronic intestinal inflammation as well as other diseases such as diabetes, obesity and even cancer. Study of the innate and adaptive immune pathways controlling bacterial colonization has however proven

  12. T lymphocytes control microbial composition by regulating the abundance of Vibrio in the zebrafish gut

    NARCIS (Netherlands)

    Brugman, Sylvia; Schneeberger, Kerstin; Witte, Merlijn; Klein, Mark R.; van den Bogert, Bartholomeus; Boekhorst, Jos; Timmerman, Harro M.; Boes, Marianne L.; Kleerebezem, Michiel; Nieuwenhuis, Edward E S

    2015-01-01

    Dysbiosis of the intestinal microbial community is considered a risk factor for development of chronic intestinal inflammation as well as other diseases such as diabetes, obesity and even cancer. Study of the innate and adaptive immune pathways controlling bacterial colonization has however proven

  13. Microbial Hub Taxa Link Host and Abiotic Factors to Plant Microbiome Variation.

    Directory of Open Access Journals (Sweden)

    Matthew T Agler

    2016-01-01

    Full Text Available Plant-associated microorganisms have been shown to critically affect host physiology and performance, suggesting that evolution and ecology of plants and animals can only be understood in a holobiont (host and its associated organisms context. Host-associated microbial community structures are affected by abiotic and host factors, and increased attention is given to the role of the microbiome in interactions such as pathogen inhibition. However, little is known about how these factors act on the microbial community, and especially what role microbe-microbe interaction dynamics play. We have begun to address this knowledge gap for phyllosphere microbiomes of plants by simultaneously studying three major groups of Arabidopsis thaliana symbionts (bacteria, fungi and oomycetes using a systems biology approach. We evaluated multiple potential factors of microbial community control: we sampled various wild A. thaliana populations at different times, performed field plantings with different host genotypes, and implemented successive host colonization experiments under lab conditions where abiotic factors, host genotype, and pathogen colonization was manipulated. Our results indicate that both abiotic factors and host genotype interact to affect plant colonization by all three groups of microbes. Considering microbe-microbe interactions, however, uncovered a network of interkingdom interactions with significant contributions to community structure. As in other scale-free networks, a small number of taxa, which we call microbial "hubs," are strongly interconnected and have a severe effect on communities. By documenting these microbe-microbe interactions, we uncover an important mechanism explaining how abiotic factors and host genotypic signatures control microbial communities. In short, they act directly on "hub" microbes, which, via microbe-microbe interactions, transmit the effects to the microbial community. We analyzed two "hub" microbes (the

  14. Modulation of tumor necrosis factor by microbial pathogens.

    Directory of Open Access Journals (Sweden)

    2006-02-01

    Full Text Available In response to invasion by microbial pathogens, host defense mechanisms get activated by both the innate and adaptive arms of the immune responses. TNF (tumor necrosis factor is a potent proinflammatory cytokine expressed by activated macrophages and lymphocytes that induces diverse cellular responses that can vary from apoptosis to the expression of genes involved in both early inflammatory and acquired immune responses. A wide spectrum of microbes has acquired elegant mechanisms to overcome or deflect the host responses mediated by TNF. For example, modulatory proteins encoded by multiple families of viruses can block TNF and TNF-mediated responses at multiple levels, such as the inhibition of the TNF ligand or its receptors, or by modulating key transduction molecules of the TNF signaling pathway. Bacteria, on the other hand, tend to modify TNF-mediated responses specifically by regulating components of the TNF signaling pathway. Investigation of these diverse strategies employed by viral and bacterial pathogens has significantly advanced our understanding of both host TNF responses and microbial pathogenesis. This review summarizes the diverse microbial strategies to regulate TNF and how such insights into TNF modulation could benefit the treatment of inflammatory or autoimmune diseases.

  15. Microbial Character Related Sulfur Cycle under Dynamic Environmental Factors Based on the Microbial Population Analysis in Sewerage System

    Science.gov (United States)

    Dong, Qian; Shi, Hanchang; Liu, Yanchen

    2017-01-01

    The undesired sulfur cycle derived by microbial population can ultimately causes the serious problems of sewerage systems. However, the microbial community characters under dynamic environment factors in actual sewerage system is still not enough. This current study aimed to character the distributions and compositions of microbial communities that participate in the sulfur cycle under the dynamic environmental conditions in a local sewerage system. To accomplish this, microbial community compositions were assessed using 454 high-throughput sequencing (16S rDNA) combined with dsrB gene-based denaturing gradient gel electrophoresis. The results indicated that a higher diversity of microbial species was present at locations in sewers with high concentrations of H2S. Actinobacteria and Proteobacteria were dominant in the sewerage system, while Actinobacteria alone were dominant in regions with high concentrations of H2S. Specifically, the unique operational taxonomic units could aid to characterize the distinct microbial communities within a sewerage manhole. The proportion of sulfate-reducing bacteria, each sulfur-oxidizing bacteria (SOB) were strongly correlated with the liquid parameters (DO, ORP, COD, Sulfide, NH3-N), while the Mycobacterium and Acidophilic SOB (M&A) was strongly correlated with gaseous factors within the sewer, such as H2S, CH4, and CO. Identifying the distributions and proportions of critical microbial communities within sewerage systems could provide insights into how the microbial sulfur cycle is affected by the dynamic environmental conditions that exist in sewers and might be useful for explaining the potential sewerage problems. PMID:28261160

  16. Microbial Character Related Sulfur Cycle under Dynamic Environmental Factors Based on the Microbial Population Analysis in Sewerage System.

    Science.gov (United States)

    Dong, Qian; Shi, Hanchang; Liu, Yanchen

    2017-01-01

    The undesired sulfur cycle derived by microbial population can ultimately causes the serious problems of sewerage systems. However, the microbial community characters under dynamic environment factors in actual sewerage system is still not enough. This current study aimed to character the distributions and compositions of microbial communities that participate in the sulfur cycle under the dynamic environmental conditions in a local sewerage system. To accomplish this, microbial community compositions were assessed using 454 high-throughput sequencing (16S rDNA) combined with dsrB gene-based denaturing gradient gel electrophoresis. The results indicated that a higher diversity of microbial species was present at locations in sewers with high concentrations of H2S. Actinobacteria and Proteobacteria were dominant in the sewerage system, while Actinobacteria alone were dominant in regions with high concentrations of H2S. Specifically, the unique operational taxonomic units could aid to characterize the distinct microbial communities within a sewerage manhole. The proportion of sulfate-reducing bacteria, each sulfur-oxidizing bacteria (SOB) were strongly correlated with the liquid parameters (DO, ORP, COD, Sulfide, NH3-N), while the Mycobacterium and Acidophilic SOB (M&A) was strongly correlated with gaseous factors within the sewer, such as H2S, CH4, and CO. Identifying the distributions and proportions of critical microbial communities within sewerage systems could provide insights into how the microbial sulfur cycle is affected by the dynamic environmental conditions that exist in sewers and might be useful for explaining the potential sewerage problems.

  17. Controls on soil microbial community stability under climate change

    Directory of Open Access Journals (Sweden)

    Franciska T De Vries

    2013-09-01

    Full Text Available Soil microbial communities are intricately linked to ecosystem functioning because they play important roles in carbon and nitrogen cycling. Still, we know little about how soil microbial communities will be affected by disturbances expected with climate change. This is a significant gap in understanding, as the stability of microbial communities, defined as a community's ability to resist and recover from disturbances, likely has consequences for ecosystem function. Here, we propose a framework for predicting a community’s response to climate change, based on specific functional traits present in the community, the relative dominance of r- and K-strategists, and the soil environment. We hypothesize that the relative abundance of r- and K-strategists will inform about a community’s resistance and resilience to climate change associated disturbances. We also propose that other factors specific to soils, such as moisture content and the presence of plants, may enhance a community’s resilience. For example, recent evidence suggests microbial grazers, resource availability, and plant roots each impact on microbial community stability. We explore these hypotheses by offering three vignettes of published data that that we re-analyzed. Our results show that community measures of the relative abundance of r- and K-strategists, as well as environmental properties like resource availability and the abundance and diversity of higher trophic levels, can contribute to explaining the response of microbial community composition to climate change-related disturbances. However, further investigation and experimental validation is necessary to directly test these hypotheses across a wide range of soil ecosystems.

  18. Microbial control of hydrogen sulfide production

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, A.D.; Bhupathiraju, V.K.; Wofford, N.; McInerney, M.J. [Univ. of Oklahoma, Tulsa, OK (United States)] [and others

    1995-12-31

    A sulfide-resistant strain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. The ability of a strain F to control sulfide production in an experimental system of cores and formation water from the Redfield, Iowa, natural gas storage facility was also investigated. A stable, sulfide-producing biofilm was established in two separate core systems, one of which was inoculated with strain F while the other core system (control) was treated in an identical manner, but was not inoculated with strain F. When formation water with 10 mM acetate and 5 mM nitrate was injected into both core systems, the effluent sulfide concentrations in the control core system ranged from 200 to 460 {mu}M. In the test core system inoculated with strain F, the effluent sulfide concentrations were lower, ranging from 70 to 110 {mu}M. In order to determine whether strain F could control sulfide production under optimal conditions for sulfate-reducing bacteria, the electron donor was changed to lactate and inorganic nutrients (nitrogen and phosphate sources) were added to the formation water. When nutrient-supplemented formation water with 3.1 mM lactate and 10 mM nitrate was used, the effluent sulfide concentrations of the control core system initially increased to about 3,800 {mu}M, and then decreased to about 1,100 {mu}M after 5 weeks. However, in the test core system inoculated with strain F, the effluent sulfide concentrations were much lower, 160 to 330 {mu}M.

  19. Trends in microbial control techniques for poultry products.

    Science.gov (United States)

    Silva, Filomena; Domingues, Fernanda C; Nerín, Cristina

    2016-07-20

    Fresh poultry meat and poultry products are highly perishable foods and high potential sources of human infection due to the presence of several foodborne pathogens. Focusing on the microbial control of poultry products, the food industry generally implements numerous preventive measures based on the Hazard Analysis and Critical Control Points (HACCP) food safety management system certification together with technological steps, such as refrigeration coupled to modified atmosphere packaging that are able to control identified potential microbial hazards during food processing. However, in recent years, to meet the demand of consumers for minimally processed, high-quality, and additive-free foods, technologies are emerging associated with nonthermal microbial inactivation, such as high hydrostatic pressure, irradiation, and natural alternatives, such as biopreservation or the incorporation of natural preservatives in packaging materials. These technologies are discussed throughout this article, emphasizing their pros and cons regarding the control of poultry microbiota and their effects on poultry sensory properties. The discussion for each of the preservation techniques mentioned will be provided with as much detail as the data and studies provided in the literature for poultry meat and products allow. These new approaches, on their own, have proved to be effective against a wide range of microorganisms in poultry meat. However, since some of these emergent technologies still do not have full consumer's acceptability and, taking into consideration the hurdle technology concept for poultry processing, it is suggested that they will be used as combined treatments or, more frequently, in combination with modified atmosphere packaging.

  20. Environmental controls on microbial communities in continental serpentinite fluids

    Directory of Open Access Journals (Sweden)

    Melitza eCrespo-Medina

    2014-11-01

    Full Text Available Geochemical reactions associated with serpentinization alter the composition of dissolved organic compounds in circulating fluids and potentially liberate mantle-derived carbon and reducing power to support subsurface microbial communities. Previous studies have identified Betaproteobacteria from the order Burkholderiales and bacteria from the order Clostridiales as key components of the serpentinite–hosted microbiome, however there is limited knowledge of their metabolic capabilities or growth characteristics. In an effort to better characterize microbial communities, their metabolism, and factors limiting their activities, microcosm experiments were designed with fluids collected from several monitoring wells at the Coast Range Ophiolite Microbial Observatory (CROMO in northern California during expeditions in March and August 2013. The incubations were initiated with a hydrogen atmosphere and a variety of carbon sources (carbon dioxide, methane, acetate and formate, with and without the addition of nutrients and electron acceptors. Growth was monitored by direct microscopic counts; DNA yield and community composition was assessed at the end of the three month incubation. For the most part, results indicate that bacterial growth was favored by the addition of acetate and methane, and that the addition of nutrients and electron acceptors had no significant effect on microbial growth, suggesting no nutrient- or oxidant-limitation. However the addition of sulfur amendments led to different community compositions. The dominant organisms at the end of the incubations were closely related to Dethiobacter sp. and to the family Comamonadaceae, which are also prominent in culture-independent gene sequencing surveys. These experiments provide one of first insights into the biogeochemical dynamics of the serpentinite subsurface environment and will facilitate experiments to trace microbial activities in serpentinizing ecosystems.

  1. Microbial larvicides for malaria control in The Gambia.

    OpenAIRE

    Green Clare; Lindsay Steven W; Majambere Silas; Kandeh Balla; Fillinger Ulrike

    2007-01-01

    Abstract Background Mosquito larval control may prove to be an effective tool for incorporating into integrated vector management (IVM) strategies for reducing malaria transmission. Here the efficacy of microbial larvicides against Anopheles gambiae s.l. was tested in preparation for a large-scale larviciding programme in The Gambia. Methods The impact of water-dispersible (WDG) and corn granule (CG) formulations of commercial Bacillus sphaericus strain 2362 (Bs; VectoLex®) and Bacillus thuri...

  2. Representing Microbial Dormancy in Soil Decomposition Models Improves Model Performance and Reveals Key Ecosystem Controls on Microbial Activity

    Science.gov (United States)

    He, Y.; Yang, J.; Zhuang, Q.; Wang, G.; Liu, Y.

    2014-12-01

    Climate feedbacks from soils can result from environmental change and subsequent responses of plant and microbial communities and nutrient cycling. Explicit consideration of microbial life history traits and strategy may be necessary to predict climate feedbacks due to microbial physiology and community changes and their associated effect on carbon cycling. In this study, we developed an explicit microbial-enzyme decomposition model and examined model performance with and without representation of dormancy at six temperate forest sites with observed soil efflux ranged from 4 to 10 years across different forest types. We then extrapolated the model to all temperate forests in the Northern Hemisphere (25-50°N) to investigate spatial controls on microbial and soil C dynamics. Both models captured the observed soil heterotrophic respiration (RH), yet no-dormancy model consistently exhibited large seasonal amplitude and overestimation in microbial biomass. Spatially, the total RH from temperate forests based on dormancy model amounts to 6.88PgC/yr, and 7.99PgC/yr based on no-dormancy model. However, no-dormancy model notably overestimated the ratio of microbial biomass to SOC. Spatial correlation analysis revealed key controls of soil C:N ratio on the active proportion of microbial biomass, whereas local dormancy is primarily controlled by soil moisture and temperature, indicating scale-dependent environmental and biotic controls on microbial and SOC dynamics. These developments should provide essential support to modeling future soil carbon dynamics and enhance the avenue for collaboration between empirical soil experiment and modeling in the sense that more microbial physiological measurements are needed to better constrain and evaluate the models.

  3. Microbial larvicides for malaria control in The Gambia

    Directory of Open Access Journals (Sweden)

    Green Clare

    2007-06-01

    Full Text Available Abstract Background Mosquito larval control may prove to be an effective tool for incorporating into integrated vector management (IVM strategies for reducing malaria transmission. Here the efficacy of microbial larvicides against Anopheles gambiae s.l. was tested in preparation for a large-scale larviciding programme in The Gambia. Methods The impact of water-dispersible (WDG and corn granule (CG formulations of commercial Bacillus sphaericus strain 2362 (Bs; VectoLex® and Bacillus thuringiensis var.israelensis strain AM65-52 (Bti; VectoBac® on larval development were tested under laboratory and field conditions to (1 identify the susceptibility of local vectors, (2 evaluate the residual effect and re-treatment intervals, (3 test the effectiveness of the microbials under operational application conditions and (4 develop a method for large-scale application. Results The major malaria vectors were highly susceptible to both microbials. The lethal concentration (LC to kill 95% of third instar larvae of Anopheles gambiae s.s. after 24 hours was 0.023 mg/l (14.9 BsITU/l for Bs WDG and 0.132 mg/l (396 ITU/l for Bti WDG. In general Bs had little residual effect under field conditions even when the application rate was 200 times greater than the LC95. However, there was a residual effect up to 10 days in standardized field tests implemented during the dry season. Both microbials achieved 100% mortality of larvae 24–48 hours post-application but late instar larvae were detected 4 days after treatment. Pupae development was reduced by 94% (95% Confidence Interval = 90.8–97.5% at weekly re-treatment intervals. Field tests showed that Bs had no residual activity against anopheline larvae. Both microbials provided complete protection when applied weekly. The basic training of personnel in identification of habitats, calibration of application equipment and active larviciding proved to be successful and achieved full coverage and control of mosquito

  4. Microbial contamination of stored hydrocarbon fuels and its control

    Directory of Open Access Journals (Sweden)

    Gaylarde Christine C.

    1999-01-01

    Full Text Available The major microbial problem in the petroleum refining industry is contamination of stored products, which can lead to loss of product quality, formation of sludge and deterioration of pipework and storage tanks, both in the refinery and at the end-user. Three major classes of fuel are discussed in this article - gasoline, aviation kerosene and diesel, corresponding to increasingly heavy petroleum fractions. The fuel that presents the most serious microbiological problems is diesel. The many microorganisms that have been isolated from hydrocarbon fuel systems are listed. The conditions required for microbial growth and the methods used to monitor and to control this activity are discussed. The effects of various fuel additives, including biocides, are considered.

  5. Mineralogical Control on Microbial Diversity in a Weathered Granite?

    Science.gov (United States)

    Gleeson, D.; Clipson, N.; McDermott, F.

    2003-12-01

    Mineral transformation reactions and the behaviour of metals in rock and soils are affected not only by physicochemical parameters but also by biological factors, particularly by microbial activity. Microbes inhabit a wide range of niches in surface and subsurface environments, with mineral-microbe interactions being generally poorly understood. The focus of this study is to elucidate the role of microbial activity in the weathering of common silicate minerals in granitic rocks. A site in the Wicklow Mountains (Ireland) has been identified that consists of an outcrop surface of Caledonian (ca. 400 million years old) pegmatitic granite from which large intact crystals of variably weathered muscovite, plagioclase, K-feldspar and quartz were sampled, together with whole-rock granite. Culture-based microbial approaches have been widely used to profile microbial communities, particularly from copiotrophic environments, but it is now well established that for oligotrophic environments such as those that would be expected on weathering faces, perhaps less than 1% of microbial diversity can be profiled by cultural means. A number of culture-independent molecular based approaches have been developed to profile microbial diversity and community structure. These rely on successfully isolating environmental DNA from a given environment, followed by the use of the polymerase chain reaction (PCR) to amplify the typically small quantities of extracted DNA. Amplified DNA can then be analysed using cloning based approaches as well as community fingerprinting systems such as denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (TRFLP) and ribosomal intergenic spacer analysis (RISA). Community DNA was extracted and the intergenic spacer region (ITS) between small (16S) and large (23S) bacterial subunit rRNA genes was amplified. RISA fragments were then electrophoresed on a non-denaturing polyacrylamide gel. Banding patterns suggest that

  6. Utilization and control of ecological interactions in polymicrobial infections and community-based microbial cell factories

    DEFF Research Database (Denmark)

    Wigneswaran, Vinoth; Amador Hierro, Cristina Isabel; Jelsbak, Lotte;

    2016-01-01

    Microbial activities are most often shaped by interactions between co-existing microbes within mixed-species communities. Dissection of the molecular mechanisms of species interactions within communities is a central issue in microbial ecology, and our ability to engineer and control microbial co...

  7. Biodiversity of benthic microbial communities in bioturbated coastal sediments is controlled by geochemical microniches.

    Science.gov (United States)

    Bertics, Victoria J; Ziebis, Wiebke

    2009-11-01

    We used a combination of field and laboratory approaches to address how the bioturbation activity of two crustaceans, the ghost shrimp Neotrypaea californiensis and the fiddler crab Uca crenulata, affects the microbial diversity in the seabed of a coastal lagoon (Catalina Harbor, Santa Catalina Island, CA, USA). Detailed geochemical analyses, including oxygen microsensor measurements, were performed to characterize environmental parameters. We used a whole-assemblage fingerprinting approach (ARISA: amplified ribosomal intergenic spacer analysis) to compare bacterial diversity along geochemical gradients and in relation to subsurface microniches. The two crustaceans have different burrowing behaviors. The ghost shrimp maintains complex, deep-reaching burrows and permanently lives subterranean, supplying its burrow with oxygen-rich water. In contrast, the fiddler crab constructs simpler, J-shaped burrows, which it does not inhabit permanently and does not actively ventilate. Our goal was to address how varying environmental parameters affect benthic microbial communities. An important question in benthic microbial ecology has been whether burrows support similar or unique communities compared with the sediment surface. Our results showed that sediment surface microbial communities are distinct from subsurface assemblages and that different burrow types support diverse bacterial taxa. Statistical comparisons by canonical correspondence analysis indicated that the availability of oxidants (oxygen, nitrate, ferric iron) play a key role in determining the presence and abundance of different taxa. When geochemical parameters were alike, microbial communities associated with burrows showed significant similarity to sediment surface communities. Our study provides implications on the community structure of microbial communities in marine sediments and the factors controlling their distribution.

  8. Mining Seasonal Marine Microbial Pattern with Greedy Heuristic Clustering and Symmetrical Nonnegative Matrix Factorization

    Directory of Open Access Journals (Sweden)

    Fei Liu

    2014-01-01

    Full Text Available With the development of high-throughput and low-cost sequencing technology, a large number of marine microbial sequences were generated. The association patterns between marine microbial species and environment factors are hidden in these large amount sequences. Mining these association patterns is beneficial to exploit the marine resources. However, very few marine microbial association patterns are well investigated in this field. The present study reports the development of a novel method called HC-sNMF to detect the marine microbial association patterns. The results show that the four seasonal marine microbial association networks have characters of complex networks, the same environmental factor influences different species in the four seasons, and the correlative relationships are stronger between OTUs (taxa than with environmental factors in the four seasons detecting community.

  9. Microbial carbon recycling: an underestimated process controlling soil carbon dynamics

    Science.gov (United States)

    Basler, A.; Dippold, M.; Helfrich, M.; Dyckmans, J.

    2015-07-01

    The mean residence times (MRT) of different compound classes of soil organic matter (SOM) do not match their inherent recalcitrance to decomposition. One reason for this is the stabilisation within the soil matrix, but recycling, i.e. the reuse of "old" organic material to form new biomass may also play a role as it uncouples the residence times of organic matter from the lifetime of discrete molecules in soil. We analysed soil sugar dynamics in a natural 30 years old labelling experiment after a~wheat-maize vegetation change to determine the extent of recycling and stabilisation in plant and microbial derived sugars: while plant derived sugars are only affected by stabilisation processes, microbial sugars may be subject to both, stabilisation and recycling. To disentangle the dynamics of soil sugars, we separated different density fractions (free particulate organic matter (fPOM), light occluded particulate organic matter (≤1.6 g cm-3; oPOM1.6), dense occluded particulate organic matter (≤2 g cm-3; oPOM2) and mineral-associated organic matter (>2 g cm-3; Mineral)) of a~silty loam under long term wheat and maize cultivation. The isotopic signature of sugars was measured by high pressure liquid chromatography coupled to isotope ratio mass spectrometry (HPLC/IRMS), after hydrolysis with 4 M Trifluoroacetic acid (TFA). While apparent mean residence times (MRT) of sugars were comparable to total organic carbon in the bulk soil and mineral fraction, the apparent MRT of sugars in the oPOM fractions were considerably lower than those of the total carbon of these fractions. This indicates that oPOM formation was fuelled by microbial activity feeding on new plant input. In the bulk soil, mean residence times of the mainly plant derived xylose (xyl) were significantly lower than those of mainly microbial derived sugars like galactose (gal), rhamnose (rha), fucose (fuc), indicating that recycling of organic matter is an important factor regulating organic matter dynamics

  10. The role of microbial low-molecular-weight autoregulatory factors (alkylhydroxybenzenes) in resistance of microorganisms to radiation and heat shock

    Science.gov (United States)

    El-Registan, Galina I.; Mulyukin, Andrey L.; Nikolaev, Yuri A.; Stepanenko, Irina Yu.; Kozlova, Alla N.; Martirosova, Elena I.; Shanenko, Elena F.; Strakhovskaya, Marina G.; Revina, Aleksandra A.

    Low-molecular-weight cell-to-cell communication factors are produced by various pro- and eukaryotes and involved in autoregulation of the growth and development of microbial cultures. As for some bacterial and yeast species, these factors were identified as isomers and homologues of alkylhydroxybenzenes (AHB). Depending on the concentration, they participate in controlling the transition to stationary phase, entering the resting state, and stress resistance of vegetative cells to gamma-irradiation, photooxidation (singlet oxygen), and heat shock. Chemical analogues of microbial AHB protected microbial cultures from stressful situations and exerted (1) the stabilizing activity toward macromolecules and (2) the ability to scavenge active oxygen species. The stabilizing effect of AHBs resulted from their complex formation with protected macromolecules due to intermolecular hydrogen bonds, hydrophobic and electrostatic interactions and was demonstrated on models of individual enzymes (trypsin). Particularly, AHBs protected the yeast from the action of (a) active oxygen species formed during gamma-irradiation (500 Gy, 1.96 Gy/s) or (b) singlet oxygen generated in cells photosensitized by chlorin e 6 (10 μg/L). It is important that microbial AHBs were not species-specific and defended cultured microbial and animal cells from the action of organic toxicants. The use of AHBs as protectants and adaptogens is discussed as well as perspectives of further investigations.

  11. Factors associated with asthma control.

    NARCIS (Netherlands)

    Vries, M.P. de; Bemt, E.A.J.M. van den; Lince, S.; Muris, J.W.M.; Thoonen, B.P.A.; Schayck, C.P. van

    2005-01-01

    The aim of this study was to evaluate which factors are associated with asthma control experienced by asthma patients. In a cross-sectional study patients aged 16-60 years with mild to moderate asthma were selected. The influence of the following factors on asthma control was studied in a multivaria

  12. Mechanisms Controlling Carbon Turnover from Diverse Microbial Groups in Temperate and Tropical Forest Soils

    Science.gov (United States)

    Throckmorton, H.; Dane, L.; Bird, J. A.; Firestone, M. K.; Horwath, W. R.

    2010-12-01

    Microorganisms represent an important intermediate along the pathway of plant litter decomposition to the formation of soil organic matter (SOM); yet little is known of the fate and stability of microbial C in soils and the importance of microbial biochemistry as a factor influencing SOM dynamics. This research investigates mechanisms controlling microbial C stabilization in a temperate forest in the Sierra Nevada of California (CA) and a tropical forest in Puerto Rico (PR). Biochemically diverse microbial groups (fungi, actinomycetes, bacteria gram (+), and bacteria gram (-)) were isolated from both sites, grown in the laboratory with C13 media, killed, and nonliving residues were added back to soils as a reciprocal transplant of microbial groups. The native microbial community in CA is dominated by fungi and in PR is dominated by bacteria, which provides an opportunity to asses the metabolic response of distinct microbial communities to the diverse microbial additions. CA and PR soils were sampled five times over a 3 and 2 year period, respectively. In CA there was no significant difference in the mean residence time (MRT) of diverse C13 microbial treatments; whereas in PR there were significant differences, whereby temperate fungi, temperate Gram (+) bacteria, and tropical actinomycetes exhibited a significantly longer MRT as compared with tropical fungi and temperate Gram (-). These results suggest that a bacterial dominated microbial community discriminates more amongst diverse substrates than a fungal-dominated community. MRT for labeled-C in CA was 5.21 ± 1.11 years, and in PR was 2.22 ± 0.45. Despite substantial differences in MRT between sites, physical fractionation of soils into light (LF), aggregated-occluded (OF), and mineral-associated (MF) fractions provided evidence that accelerated decomposition in PR (presumably due to climate) operated primarily on labeled-C unassociated with the mineral matrix (LF); labeled-C occluded within aggregates (OF) or

  13. Microbial Populations of Stony Meteorites: Substrate Controls on First Colonizers

    Directory of Open Access Journals (Sweden)

    Alastair W. Tait

    2017-06-01

    Full Text Available Finding fresh, sterilized rocks provides ecologists with a clean slate to test ideas about first colonization and the evolution of soils de novo. Lava has been used previously in first colonizer studies due to the sterilizing heat required for its formation. However, fresh lava typically falls upon older volcanic successions of similar chemistry and modal mineral abundance. Given enough time, this results in the development of similar microbial communities in the newly erupted lava due to a lack of contrast between the new and old substrates. Meteorites, which are sterile when they fall to Earth, provide such contrast because their reduced and mafic chemistry commonly differs to the surfaces on which they land; thus allowing investigation of how community membership and structure respond to this new substrate over time. We conducted 16S rRNA gene analysis on meteorites and soil from the Nullarbor Plain, Australia. We found that the meteorites have low species richness and evenness compared to soil sampled from directly beneath each meteorite. Despite the meteorites being found kilometers apart, the community structure of each meteorite bore more similarity to those of other meteorites (of similar composition than to the community structure of the soil on which it resided. Meteorites were dominated by sequences that affiliated with the Actinobacteria with the major Operational Taxonomic Unit (OTU classified as Rubrobacter radiotolerans. Proteobacteria and Bacteroidetes were the next most abundant phyla. The soils were also dominated by Actinobacteria but to a lesser extent than the meteorites. We also found OTUs affiliated with iron/sulfur cycling organisms Geobacter spp. and Desulfovibrio spp. This is an important finding as meteorites contain abundant metal and sulfur for use as energy sources. These ecological findings demonstrate that the structure of the microbial community in these meteorites is controlled by the substrate, and will not

  14. Microbial Populations of Stony Meteorites: Substrate Controls on First Colonizers.

    Science.gov (United States)

    Tait, Alastair W; Gagen, Emma J; Wilson, Siobhan A; Tomkins, Andrew G; Southam, Gordon

    2017-01-01

    Finding fresh, sterilized rocks provides ecologists with a clean slate to test ideas about first colonization and the evolution of soils de novo. Lava has been used previously in first colonizer studies due to the sterilizing heat required for its formation. However, fresh lava typically falls upon older volcanic successions of similar chemistry and modal mineral abundance. Given enough time, this results in the development of similar microbial communities in the newly erupted lava due to a lack of contrast between the new and old substrates. Meteorites, which are sterile when they fall to Earth, provide such contrast because their reduced and mafic chemistry commonly differs to the surfaces on which they land; thus allowing investigation of how community membership and structure respond to this new substrate over time. We conducted 16S rRNA gene analysis on meteorites and soil from the Nullarbor Plain, Australia. We found that the meteorites have low species richness and evenness compared to soil sampled from directly beneath each meteorite. Despite the meteorites being found kilometers apart, the community structure of each meteorite bore more similarity to those of other meteorites (of similar composition) than to the community structure of the soil on which it resided. Meteorites were dominated by sequences that affiliated with the Actinobacteria with the major Operational Taxonomic Unit (OTU) classified as Rubrobacter radiotolerans. Proteobacteria and Bacteroidetes were the next most abundant phyla. The soils were also dominated by Actinobacteria but to a lesser extent than the meteorites. We also found OTUs affiliated with iron/sulfur cycling organisms Geobacter spp. and Desulfovibrio spp. This is an important finding as meteorites contain abundant metal and sulfur for use as energy sources. These ecological findings demonstrate that the structure of the microbial community in these meteorites is controlled by the substrate, and will not reach homeostasis

  15. Large-scale environmental controls on microbial biofilms in high-alpine streams

    Directory of Open Access Journals (Sweden)

    T. J. Battin

    2004-01-01

    Full Text Available Glaciers are highly responsive to global warming and important agents of landscape heterogeneity. While it is well established that glacial ablation and snowmelt regulate stream discharge, linkage among streams and streamwater geochemistry, the controls of these factors on stream microbial biofilms remain insufficiently understood. We investigated glacial (metakryal, hypokryal, groundwater-fed (krenal and snow-fed (rhithral streams - all of them representative for alpine stream networks - and present evidence that these hydrologic and hydrogeochemical factors differentially affect sediment microbial biofilms. Average microbial biomass and bacterial carbon production were low in the glacial streams, whereas bacterial cell size, biomass, and carbon production were higher in the tributaries, most notably in the krenal stream. Whole-cell in situ fluorescence hybridization revealed reduced detection rates of the Eubacteria and higher abundance of α-Proteobacteria in the glacial stream, a pattern that most probably reflects the trophic status of this ecosystem. Our data suggest low flow during the onset of snowmelt and autumn as a short period (hot moment of favorable environmental conditions with pulsed inputs of allochthonous nitrate and dissolved organic carbon, and with disproportionately high microbial growth. Tributaries are relatively more constant and favorable environments than kryal streams, and serve as possible sources of microbes and organic matter to the main glacial channel during periods (e.g., snowmelt of elevated hydrologic linkage among streams. Ice and snow dynamics - and their impact on the amount and composition of dissolved organic matter - have a crucial impact on stream biofilms, and we thus need to consider microbes and critical hydrological episodes in future models of alpine stream communities.

  16. Microbial control of the dark end of the biological pump

    NARCIS (Netherlands)

    Herndl, G.J.; Reinthaler, T.

    2013-01-01

    A fraction of the carbon captured by phytoplankton in the sunlit surface ocean sinks to depth as dead organic matter and faecal material. The microbial breakdown of this material in the subsurface ocean generates carbon dioxide. Collectively, this microbially mediated flux of carbon from the atmosph

  17. The role of microbial low-molecular-weight autoregulatory factors (alkylhydroxybenzenes) in resistance of microorganisms to radiation

    Science.gov (United States)

    El-Registan, G. I.; Mulyukin, A. L.; Nikolaev, Yu. A.; Stepanenko, I. Yu.; Shanenko, E. A.; Strakhovskaya, M. G.; Revina, A. A.

    Low-molecular-weight cell-to-cell communication factors are produced by various pro- and eukaryotes and involved in autoregulation of the growth and development of microbial cultures. As for some bacterial and yeast species, these factors were identified as isomers and homologs of alkylhydroxybenzenes (AHBs). Depending on the concentration, they participate in controlling the transition to stationary phase, entering the resting state, and stress resistance of vegetative cells to gamma-irradiation, photooxidation (singlet oxygen), heat shock. Chemical analogs of microbial AHBs protected microbial cultures from stressful situations and prolonged starvation and exerted (1) the stabilizing activity toward biomacromolecules and supermolecular structures (cell membranes) and (2) the ability to scavenge active oxygen species. The stabilizing effect of AHBs as chemical chaperones resulted from their complex formation with protected macromolecules due to intermolecular hydrogen bonds, hydrophobic and electrostatic interactions and was demonstrated on models of individual enzymes (trypsin, amylase, etc.). The action of AHBs as active oxygen species scavengers was related to their oxidative conversion to water-insoluble polymeric products. Particularly, AHBs protected the yeast from the action of (a) active oxygen species formed during gamma-irradiation (50 krad, 196 rad/sec) or (b) singlet oxygen generated in cells photosensitized by chlorin e6 (10 mkg/L). It is important that microbial AHBs were not species-specific and defended cultured animal cells (ras-transformed fibroblasts) from the action of organic toxicants. The use of AHBs as protectants and adaptogens will be discussed as well as perspectives of further investigations.

  18. Effects of defaunator combined with microbial growth factors on ruminal digestibility ofrice

    Directory of Open Access Journals (Sweden)

    Amlius Thalib

    1998-10-01

    Full Text Available A system of defaunating agent combined with microbial growth factors (FPM was conducted to improve the ruminal digestion of rice straw. Combination of methanol-extracted Sapindus rarak fruit (EKM with each FPM was added into anaerobic medium of ruminal fermentation. Rice straw was used as substrate and inoculum used was rumen fluid of sheep. Fermentation microbial of the substrate was incubated at 39°C for 96 hours. The experiment consisted of 10 treatments: control without EKM; control + EKM (1 .000 ppm; control +EKM combined with Zn (8 ppm, Cu (0 .8 ppm, folic acid (0.1 ppm, thiaminhydrochloride (0 .05 ppm, riboflavin (0.05 ppm, phenylpropionic acid (100 ppm, molasses (45 ppin, and mixture of all FPM used (Mix FPM. Measurements were: gas production; protozoal and bacterial populations; contents of volatile fatty acids (VFA, lactic acid andNH3N; pH ofmedium. The results show that FPM increase EKM effects on rwninal digestibility of rice straw except treatments of thiaminhydrocloride and riboflavin. The highest cumulative gas production was obtained by treatment of EKM combined with Mix FPM (168 ml versus 91 nrl of treatment of EKM with out FPM. EKM individually or combined with FPM could eliminate 46-83% protozoal population, where the highest elimination of protozoal population was given by combination of EKM with Mix FPM(83%: Elimination of protozoal population caused increment of bacterial population on all treatments except on folic acid treatment. The highest increment ofbacterial population was given by treatment of combination EKMwith Mix FPM (>500%. Therefore combination of EKMwith Mix FPM is concluded to be the most effective in improving ruminal digestibility of rice straw.

  19. Control of microbially generated hydrogen sulfide in produced waters

    Energy Technology Data Exchange (ETDEWEB)

    Burger, E.D.; Vance, I.; Gammack, G.F.; Duncan, S.E.

    1995-12-31

    Production of hydrogen sulfide in produced waters due to the activity of sulfate-reducing bacteria (SRB) is a potentially serious problem. The hydrogen sulfide is not only a safety and environmental concern, it also contributes to corrosion, solids formation, a reduction in produced oil and gas values, and limitations on water discharge. Waters produced from seawater-flooded reservoirs typically contain all of the nutrients required to support SRB metabolism. Surface processing facilities provide a favorable environment in which SRB flourish, converting water-borne nutrients into biomass and H{sub 2}S. This paper will present results from a field trial in which a new technology for the biochemical control of SRB metabolism was successfully applied. A slip stream of water downstream of separators on a produced water handling facility was routed through a bioreactor in a side-steam device where microbial growth was allowed to develop fully. This slip stream was then treated with slug doses of two forms of a proprietary, nonbiocidal metabolic modifier. Results indicated that H{sub 2}S production was halted almost immediately and that the residual effect of the treatment lasted for well over one week.

  20. Perception and regulatory principles of microbial growth control.

    Science.gov (United States)

    Khonsari, Armin S; Kollmann, Markus

    2015-01-01

    Fast growth represents an effective strategy for microbial organisms to survive in competitive environments. To accomplish this task, cells must adapt their metabolism to changing nutrient conditions in a way that maximizes their growth rate. However, the regulation of the growth related metabolic pathways can be fundamentally different among microbes. We therefore asked whether growth control by perception of the cell's intracellular metabolic state can give rise to higher growth than by direct perception of extracellular nutrient availability. To answer this question, we created a simplified dynamical computer model of a cellular metabolic network whose regulation was inferred by an optimization approach. We used this model for a competing species experiment, where a species with extracellular nutrient perception competes against one with intracellular nutrient perception by evaluating their respective average growth rate. We found that the intracellular perception is advantageous under situations where the up and down regulation of pathways cannot follow the fast changing nutrient availability in the environment. In this case, optimal regulation ignores any other nutrients except the most preferential ones, in agreement with the phenomenon of catabolite repression in prokaryotes. The corresponding metabolic pathways remain activated, despite environmental fluctuations. Therefore, the cell can take up preferential nutrients as soon as they are available without any prior regulation. As a result species that rely on intracellular perception gain a relevant fitness advantage in fluctuating nutrient environments, which enables survival by outgrowing competitors.

  1. Microbial control of hydrogen sulfide production in a porous medium

    Energy Technology Data Exchange (ETDEWEB)

    McInerney, M.J.; Wofford, N.Q. [Univ. of Oklahoma, Norman, OK (United States); Sublette, K.L. [Univ. of Tulsa, OK (United States)

    1996-12-31

    The ability of a sulfide- and glutaraldehyde-tolerant strain of Thiobacillus denitrificans (strain F) to control sulfide production in an experimental system of cores and formation water from the Redfield, Iowa natural gas storage facility was investigated. A stable, sulfide-producing biofilm was established in two separate core systems, one of which was inoculated with strain F, and the other core system (control) was treated in an identical manner, but was not inoculated with strain F. When formation water with 10 mM acetate and 5mM nitrate was injected into both core systems, the effluent sulfide concentrations in the control core system ranged from 200-460 {mu}M. In the test core system inoculated with strain F, the effluent sulfide concentrations were lower, ranging from 70-110 {mu}M. In order to determine whether strain F could control sulfide production under optimal conditions for sulfate-reducing bacteria, the electron donor was changed to lactate, and inorganic nutrients (nitrogen and phosphate sources) were added to the formation water. When nutrient-supplemented formation water with 3.1 mM lactate and 10 mM nitrate was used, the effluent sulfide concentrations of the control core system initially increased to about 3800 pM, and then decreased to about 1100 {mu}M after 5 wk. However, in the test core system inoculated with strain F, the effluent sulfide concentrations were much lower, 160-330 {mu}M. Nitrate consumption (5 mM) and high concentrations (101-1011 cells/mL) of strain F were detected in the test core system. An accumulation of biomass occurred in the influent lines during 2 mo of continuous operation, but only a small increase in injection pressure was observed. These studies showed that inoculation with strain F was needed for effective control of sulfide production, and that significant plugging or loss of injectivity owing to microbial inoculation did not occur. 7 refs., 3 figs., 1 tab.

  2. Evaluation of the Adequacy of GMP to Control Microbial Hazards in Dairy Factories in Fars Province

    Directory of Open Access Journals (Sweden)

    Sajjad Abdi no

    2016-07-01

    Full Text Available Background and Objectives: Pre-requisite programs (PRPs are “primary conditions and requirements essential for HACCP operations, which are crucial in food safety programs”. The present study was conducted to evaluate the impact of implementation of PRPs on the microbial parameters of pasteurized milk (according to the National Standard of Iran. Effectiveness of HACCP operation requirements and efficiency of Good Laboratory Practice (GLP were also evaluated in control of the above-mentioned microbial parameters. Materials and Methods: According to the approved checklist of the Vice-chancellor in Food and Drug affairs, PRPs of 26 factories were evaluated from March 2014 to March 2015 in two-month intervals, and their total and component scores were obtained along with the microbial parameters of pasteurized milk. Generalized Estimating Equations (GEEs were used to determine the significance of total score and the impact of its components on controlling microbial hazards. Results: There was a reverse significant relation between the total scores of the PRPs and microbial hygiene indices (total and coliform count which approves the effectiveness of operating the programs in controlling the mentioned microorganisms. Efficiency of each pre-requisite program was different in controlling the microbial parameters. Good Laboratory Practice (GLP had a prominent effect on controlling of the index microorganisms of hygienic operations. Overall, the results showed a little probability of contamination with E. coli in the pasteurized milk samples of Fars Province for which the statistical analysis was ignored. Conclusions: The exact operation of PRPs resulted in reduction of microbial parameters in a way that increasing the total score of PRPs led to decrease in microbial parameters of total count (TC, coliforms, molds and yeasts. The findings further suggest the application of this checklist in evaluation and prediction of microbial parameters. Keywords

  3. Influence of geogenic factors on microbial communities in metallogenic Australian soils.

    Science.gov (United States)

    Reith, Frank; Brugger, Joel; Zammit, Carla M; Gregg, Adrienne L; Goldfarb, Katherine C; Andersen, Gary L; DeSantis, Todd Z; Piceno, Yvette M; Brodie, Eoin L; Lu, Zhenmei; He, Zhili; Zhou, Jizhong; Wakelin, Steven A

    2012-11-01

    Links between microbial community assemblages and geogenic factors were assessed in 187 soil samples collected from four metal-rich provinces across Australia. Field-fresh soils and soils incubated with soluble Au(III) complexes were analysed using three-domain multiplex-terminal restriction fragment length polymorphism, and phylogenetic (PhyloChip) and functional (GeoChip) microarrays. Geogenic factors of soils were determined using lithological-, geomorphological- and soil-mapping combined with analyses of 51 geochemical parameters. Microbial communities differed significantly between landforms, soil horizons, lithologies and also with the occurrence of underlying Au deposits. The strongest responses to these factors, and to amendment with soluble Au(III) complexes, was observed in bacterial communities. PhyloChip analyses revealed a greater abundance and diversity of Alphaproteobacteria (especially Sphingomonas spp.), and Firmicutes (Bacillus spp.) in Au-containing and Au(III)-amended soils. Analyses of potential function (GeoChip) revealed higher abundances of metal-resistance genes in metal-rich soils. For example, genes that hybridised with metal-resistance genes copA, chrA and czcA of a prevalent aurophillic bacterium, Cupriavidus metallidurans CH34, occurred only in auriferous soils. These data help establish key links between geogenic factors and the phylogeny and function within soil microbial communities. In particular, the landform, which is a crucial factor in determining soil geochemistry, strongly affected microbial community structures.

  4. Control of dialysis water by microbial contamination and bacterial endotoxin tests

    Directory of Open Access Journals (Sweden)

    Fesem BAŞARI

    2012-01-01

    Full Text Available Objective: The aim of this study was to evaluate the microbial contamination and bacterial endotoxin levels in dialysis water samples sent to the Water and Food Microbiology Laboratory of the Adana Hygiene Institute Refik Saydam Hygiene Center, and to assess factors that might influence the results of these tests.Method: Two hundred fourty five dialysis water samples sent to the laboratory between January 2009 and December 2010 were tested; all of them for microbial contamination and 198 of them for bacterial endotoxin levels. Microbial contamination was evaluated by using the Plate Count Agar (PCA method while the Limulus Amoebocyte Lysate (LAL assay was used for the detection of bacterial endotoxins. The results were evaluated according to the criteria of the “Directives on the Water Purification Systems” and “the European Pharmacopoeia”. To compare the annual differences, the chi-square test was used for statistical evaluation and results with p0.05in 2010. On the other hand, in 26.7% of the dialysiswater samples the levels of bacterial endotoxinswas higher than 0.25 İU/ml in 2009, this percentagedropped to 16.5% in 2010 (p>0.05. During 2009-2010,245 microbial contamination tests were performedand in 20 (8.2% of the samples the TAMC values werehigher than 100 CFU/ml, while in 43 (21.7% out of198 of the samples the bacterial endotoxin levelswere higher than 0.25 İU/ml. Out of 20 in 43 samples,a bacterial endotoxin levels were >0.25 İU/ml werealso found as microbiologically contaminated ( >100CFU/ml, while in remaining 23 samples the level was<100 CFU/ml. There were no statistically significantdifferences in the percentages of positives found in2009 and 2010.Conclusion: The results of our study indicatethat the detection of endotoxins is a complementaryfactor to microbial contamination in the bacteriologicalmonitoring of dialysis waters. We recommend thatlevel of endotoxin should be taken into accountwhen the bacterial contamination

  5. Physical and ecological controllers of the microbial responses to drying and rewetting in soil

    Science.gov (United States)

    Leizeaga, Ainara; Meisner, Annelein; Bååth, Erland; Rousk, Johannes

    2017-04-01

    Soil moisture is one of the most powerful factors that regulate microbial activity in soil. The variation of moisture leads to drying-rewetting (DRW) events which are known to induce enormous dynamics in soil biogeochemistry; however, the microbial underpinnings are mostly unknown. Rewetting a dry soil can result in two response patterns of bacterial growth. In the Type 1 response, bacteria start growing immediately after rewetting with rates that increase in a linear fashion to converge with those prior to the DRW within hours. This growth response coincides with respiration rates that peak immediately after rewetting to then exponentially decrease. In the Type 2 response, bacterial growth remains very low after rewetting during a lag period of up to 20 hours. Bacteria then increase their growth rates exponentially to much higher rates than those before the DRW event. This growth response coincides with respiration rates that increase to high rates immediately after rewetting that then remain elevated and sometimes even increase further in sync with the growth increase. Previous studies have shown that (i) extended drying (ii) starving before DRW and (iii) inhibitors combined with drought could change the bacterial response from Type 1 to Type 2. This suggested that the response of bacteria upon rewetting could be related to the harshness of the disturbance as experienced by the microbes. In the present study, we set out to study if reduced harshness could change a Type 2 response into a Type 1 response. We hypothesized that (1) a reduced physical harshness of drying and (2) induced tolerance to drying in microbial communities could change a Type 2 response into a Type 1 growth response upon rewetting. To address this, two experiments were performed. First, soils were partially dried to different water contents and bacterial response upon rewetting was measured. Second, soils were exposed to repeated DRW cycles (Type 2 to a Type 1. Even after a Type 1 response was

  6. Soil Microbial Community Responses to Long-Term Global Change Factors in a California Grassland

    Science.gov (United States)

    Qin, K.; Peay, K.

    2015-12-01

    Soil fungal and bacterial communities act as mediators of terrestrial carbon and nutrient cycling, and interact with the aboveground plant community as both pathogens and mutualists. However, these soil microbial communities are sensitive to changes in their environment. A better understanding of the response of soil microbial communities to global change may help to predict future soil microbial diversity, and assist in creating more comprehensive models of terrestrial carbon and nutrient cycles. This study examines the effects of four global change factors (increased temperature, increased variability in precipitation, nitrogen deposition, and CO2 enrichment) on soil microbial communities at the Jasper Ridge Global Change Experiment (JRGCE), a full-factorial global change manipulative experiment on three hectares of California grassland. While similar studies have examined the effects of global change on soil microbial communities, few have manipulated more factors or been longer in duration than the JRGCE, which began field treatments in 1998. We find that nitrogen deposition, CO2 enrichment, and increased variability in precipitation significantly affect the structure of both fungal and bacterial communities, and explain more of the variation in the community structures than do local soil chemistry or aboveground plant community. Fungal richness is correlated positively with soil nitrogen content and negatively with soil water content. Arbuscular mycorrhizal fungi (AMF), which associate closely with herbaceous plants' roots and assist in nutrient uptake, decrease in both richness and relative abundance in elevated CO2 treatments.

  7. Effect of Kelp Residue Microbial Fertilizer on Eco-Control Peanut Pathogenic Fungus Aspergillus Parasiticus 1

    Institute of Scientific and Technical Information of China (English)

    Wei Xiao; Peisheng Yan

    2016-01-01

    Ecological prevention and control of plant disease is very important in sustainable agriculture. Adjusting soil pH value and fertilizing organic microbial fertilizer are two effective measures in this process. Kelp residue contains a large amount of organic compounds and alkaline metal ions. The bio⁃control Bacillus amyloliquefaciens strain Hitwh⁃BA2 was inoculated into kelp residue medium to produce kelp residue microbial fertilizer. Acidic soil and alkaline soil were used to study the effect of kelp residue microbial fertilizer on soil pH and soil suppressive activity. Tip⁃culture method was used to determine soil leachate suppressive activity, which characterized the soil suppressive activity. Results showed that fertilizing kelp residue microbial fertilizer had increased the soil pH and soil suppressive ability significantly, which was verified by peanut validation experiments as well. Peanut potting experiments proved that fertilizing kelp residue microbial fertilizer not only improved the yield of peanuts obviously, but also reduced the amount of Aspergillus parasiticus 95 in peanut geocarposphere soil significantly. Results also showed that fertilizing kelp residue microbial fertilizer was effective in reducing A. parasiticus 95 infection rate. So the kelp residue microbial fertilizer has good potential application prospect on ecological prevention and control of plant disease.

  8. From Metchnikoff to Monsanto and beyond: the path of microbial control.

    Science.gov (United States)

    Lord, Jeffrey C

    2005-05-01

    In 125 years since Metchnikoff proposed the use of Metarhizium anisopliae to control the wheat cockchafer and brought about the first field trials, microbial control has progressed from the application of naturalists' observations to biotechnology and precision delivery. This review highlights major milestones in its evolution and presents a perspective on its current direction. Fungal pathogens, the most eye-catching agents, dominated the early period, but major mycological control efforts for chinch bugs and citrus pests in the US had questionable success, and interest waned. The discoveries of Bacillus popilliae and Bacillus thuringiensis began the era of practical and commercially viable microbial control. A program to control the Japanese beetle in the US led to the discovery of both B. popilliae and Steinernema glaseri, the first nematode used as a microbial control agent. Viral insect control became practical in the latter half of the 20th century, and the first registration was obtained with the Heliothis nuclear polyhedrosis virus in 1975. Now strategies are shifting for microbial control. While Bt transgenic crops are now planted on millions of hectares, the successes of more narrowly defined microbial control are mainly in small niches. Commercial enthusiasm for traditional microbial control agents has been unsteady in recent years. The prospects of microbial insecticide use on vast areas of major crops are now viewed more realistically. Regulatory constraints, activist resistance, benign and efficacious chemicals, and limited research funding all drive changes in focus. Emphasis is shifting to monitoring, conservation, integration with chemical pesticides, and selection of favorable venues such as organic agriculture and countries that have low costs, mild regulatory climates, modest chemical inputs, and small scale farming.

  9. In Situ Microbial Community Control of the Stability of Bio-reduced Uranium

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, Brett, R.; Peacock, Aaron, D.; Resch, Charles, T.; Arntzen, Evan; Smithgall, Amanda, N.; Pfiffner, Susan; Gan, M.; McKinley, James, P.; Long, Philip, E.; White, David, C.

    2008-03-28

    In aerobic aquifers typical of many Department of Energy (DOE) legacy waste sites, uranium is present in the oxidized U(VI) form which is more soluble and thus more mobile. Field experiments at the Old Rifle UMTRA site have demonstrated that biostimulation by electron donor addition (acetate) promotes biological U(VI) reduction (2). However, U(VI) reduction is reversible and oxidative dissolution of precipitated U(IV) after the cessation of electron donor addition remains a critical issue for the application of biostimulation as a treatment technology. Despite the potential for oxidative dissolution, field experiments at the Old Rifle site have shown that rapid reoxidation of bio-reduced uranium does not occur and U(VI) concentrations can remain at approximately 20% of background levels for more than one year. The extent of post-amendment U(VI) removal and the maintenance of bioreduced uranium may result from many factors including U(VI) sorption to iron-containing mineral phases, generation of H2S or FeS0.9, or the preferential sorption of U(VI) by microbial cells or biopolymers, but the processes controlling the reduction and in situ reoxidation rates are not known. To investigate the role of microbial community composition in the maintenance of bioreduced uranium, in-well sediment incubators (ISIs) were developed allowing field deployment of amended and native sediments during on-going experiments at the site. Field deployment of the ISIs allows expedient interrogation of microbial community response to field environmental perturbations and varying geochemical conditions.

  10. Microbial PAH-Degradation in Soil: Degradation Pathways and Contributing Factors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-Xiang; CHENG Shu-Pei; ZHU Cheng-Jun; SUN Shi-Lei

    2006-01-01

    Adverse effects on the environment and high persistence in the microbial degradation and environmental fate of polycyclic aromatic hydrocarbons (PAHs) are motivating interest. Many soil microorganisms can degrade PAHs and use various metabolic pathways to do so. However, both the physio-chemical characteristics of compounds as well as the physical, chemical, and biological properties of soils can drastically influence the degradation capacity of naturally occurring microorganisms for field bioremediation. Modern biological techniques have been widely used to promote the efficiency of microbial PAH-degradation and make the biodegradation metabolic pathways more clear. In this review microbial degradation of PAHs in soil is discussed, with emphasis placed on the main degradation pathways and the environmental factors affecting biodegradation.

  11. Control of microbial fuel cell voltage using a gain scheduling control strategy

    Science.gov (United States)

    Boghani, Hitesh C.; Michie, Iain; Dinsdale, Richard M.; Guwy, Alan J.; Premier, Giuliano C.

    2016-08-01

    Recent microbial fuel cell (MFC) research frequently addresses matters associated with scale and deployability. Modularisation is often needed to reduce ohmic losses with increasing volume. Series/parallel is then often an obvious strategy to enhance power quality during operation, to make best use of generated electricity. Hence, voltage reversal resulting from power and voltage mismatch between cells become virtually unavoidable. Control MFC voltages could be used to stabilise MFC stacks. Here, nonlinear MFCs are controlled using simple gain scheduled Proportional + Integral actions. Parsimonious control may be necessary for implementation in MFC arrays, so minimising costs. Controller parameterisation used several linearised models over the dynamic operating range of the MFCs. Controller gains were then scheduled according to the operating conditions. A digital potentiometer was used to actuate the control, varying the current sourced from the MFC. The results show that the controller was able to control MFC voltages, rejecting the disturbances. It was shown that the controller was transferable between MFCs with different power performances. This study demonstrates that the control of MFCs can be achieved with relatively simple digital approaches, plausibly implementable using low cost microcontrollers, and likely to be useful in the effective deployment of MFCs in large scale arrays.

  12. Microbial Gas Production Used to Achieve Autonomous Buoyancy Control

    Science.gov (United States)

    2010-09-01

    counter weight. The microbe used is cultured in the Erlenmeyer flask. Clostridium acetobutylicum for micro1bial ballast In order to utilize microbial...34 20 0 --100% 0 20 40 60 80 Time(hr) Figure 6. Gas production by different S()lid-phase agar cultures of C. acetobutvlicum. Clostridium ... acetobutylicum as our model microbe; a gram-positive anaerobic bacterium known for its ability to produce hydrogen gas 4,5 To determine if there

  13. Microbial control of the dark end of the biological pump

    Science.gov (United States)

    Herndl, Gerhard J.; Reinthaler, Thomas

    2013-09-01

    A fraction of the carbon captured by phytoplankton in the sunlit surface ocean sinks to depth as dead organic matter and faecal material. The microbial breakdown of this material in the subsurface ocean generates carbon dioxide. Collectively, this microbially mediated flux of carbon from the atmosphere to the ocean interior is termed the biological pump. In recent decades it has become clear that the composition of the phytoplankton community in the surface ocean largely determines the quantity and quality of organic matter that sinks to depth. This settling organic matter, however, is not sufficient to meet the energy demands of microbes in the dark ocean. Two additional sources of organic matter have been identified: non-sinking organic particles of debated origin that escape capture by sediment traps and exhibit stable concentrations throughout the dark ocean, and microbes that convert inorganic carbon into organic matter. Whether these two sources can together account for the significant mismatch between organic matter consumption and supply in the dark ocean remains to be seen. It is clear, however, that the microbial community of the deep ocean works in a fundamentally different way from surface water communities.

  14. Microbial control of the dark end of the biological pump.

    Science.gov (United States)

    Herndl, Gerhard J; Reinthaler, Thomas

    2013-09-01

    A fraction of the carbon captured by phytoplankton in the sunlit surface ocean sinks to depth as dead organic matter and faecal material. The microbial breakdown of this material in the subsurface ocean generates carbon dioxide. Collectively, this microbially mediated flux of carbon from the atmosphere to the ocean interior is termed the biological pump. In recent decades it has become clear that the composition of the phytoplankton community in the surface ocean largely determines the quantity and quality of organic matter that sinks to depth. This settling organic matter, however, is not sufficient to meet the energy demands of microbes in the dark ocean. Two additional sources of organic matter have been identified: non-sinking organic particles of debated origin that escape capture by sediment traps and exhibit stable concentrations throughout the dark ocean, and microbes that convert inorganic carbon into organic matter. Whether these two sources can together account for the significant mismatch between organic matter consumption and supply in the dark ocean remains to be seen. It is clear, however, that the microbial community of the deep ocean works in a fundamentally different way from surface water communities.

  15. Hydrographic controls on marine organic matter fate and microbial diversity in the western Irish Sea

    Science.gov (United States)

    O'Reilly, Shane; Szpak, Michal; Monteys, Xavier; Flanagan, Paul; Allen, Christopher; Kelleher, Brian

    2014-05-01

    Cycling of organic matter (OM) is the key biological process in the marine environment1 and knowledge of the sources and the reactivity of OM, in addition to factors controlling its distribution in estuarine, coastal and shelf sediments are of key importance for understanding global biogeochemical cycles2. With recent advances in cultivation-independent molecular approaches to microbial ecology, the key role of prokaryotes in global biogeochemical cycling in marine ecosystems has been emphasised3,4. However, spatial studies combining the distribution and fate of OM with microbial community abundance and diversity remain rare. Here, a combined spatial lipid biomarker and 16S rRNA tagged pyrosequencing study was conducted in surface sediments and particulate matter across hydrographically distinct zones associated with the seasonal western Irish Sea gyre. The aim was to assess the spatial variation of, and factors controlling, marine organic cycling and sedimentary microbial communities across these distinct zones. The distribution of phospholipid fatty acids, source-specific sterols, wax esters and C25 highly branched isoprenoids indicate that diatoms, dinoflagellates and green algae were the major contributors of marine organic matter, while the distribution of cholesterol, wax esters and C20 and C22 polyunsaturated fatty acids have highlighted the importance of copepod grazing for mineralizing organic matter in the water column5. This marine OM production and mineralisation was greatest in well-mixed waters compared to offshore stratified waters. Lipid analysis and 16S rRNA PCR-DGGE profiling also suggests that sedimentary bacterial abundance increases while community diversity decreases in offshore stratified waters. The major bacterial classes are the Deltaproteobacteria, Clostridia, Flavobacteriia, Gammaproteobactera and Bacteroiidia. At the family/genus level most groups appear to be associated with organoheterotrophic processing of sedimentary OM, ranging

  16. Microbial Factors and Antimicrobial Strategies in Dental Pulp Regeneration.

    Science.gov (United States)

    Fouad, Ashraf F

    2017-09-01

    Dental pulp regeneration after pulp necrosis in immature teeth represents a major departure from traditional endodontic therapy of these conditions. Preliminary clinical attempts have shown the feasibility of developing mineralized repair tissue, which may provide a clinically acceptable outcome. However, this outcome may not provide sufficient host response and root strength to ensure the longevity of the involved teeth. It is not clear if these preliminary suboptimal results are caused by the inability to fully disinfect the pulp space or the absence of a suitable progenitor cell/scaffold template together with adequate vascularity. Moreover, it is not known to what degree the root canal system needs to be disinfected in order for clinical success to be evident. This article describes the current clinical strategies and protocols for the optimal disinfection and preparation of the pulp space environment to promote periapical healing as well as soft and hard tissue development after an infectious process. Current and future strategies for disinfecting the pulp space with minimal disruption of the necessary biological factors from dentin, the progenitor cells in periapical vital tissues, and the vascularity are discussed. The potential for success of pulp regeneration after necrosis and infection would transform the practice of endodontics, even for mature teeth. This is a goal worth pursuing because it would achieve the restoration of normal host responses in the pulp space and the regeneration of destroyed dental tissues. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Control of Boreal Forest Soil Microbial Communities and Processes by Plant Secondary Compounds

    Science.gov (United States)

    Leewis, M. C.; Leigh, M. B.

    2016-12-01

    Plants release an array of secondary plant metabolites (SPMEs), which vary widely between plant species/progenies and may drive shifts in soil microbial community structure and function. We hypothesize that SPMEs released through litterfall and root turnover in the boreal forest control ecosystem carbon cycling by inhibiting microbial decomposition processes, which are overcome partially by increased aromatic biodegradation of microbial communities that also fortuitously prime soils for accelerated biodegradation of contaminants. Soils and litter (stems, roots, senescing leaves) were collected from 3 different birch progenies from Iceland, Finland, and Siberia that have been reported to contain different SPME content (low, medium, high, respectively) due to differences in herbivory pressure over their natural history, as well as black spruce, all growing in a long-term common tree garden at the Kevo Subarctic Field Research Institute, Finland. We characterized the SPME content of these plant progenies and used a variety of traditional microbiological techniques (e.g., enzyme assays, litter decomposition and contaminant biodegradation rates) and molecular techniques (e.g., high-throughput amplicon sequencing for bacteria and fungi) to assess how different levels of SPMEs may correlate to shifts in microbial community structure and function. Microbial communities (bacterial and fungal) significantly varied in composition as well as leaf litter and diesel biodegradation rates, in accordance with the phytochemistry of the trees present. This study offers novel, fundamental information about phytochemical controls on ecosystem processes, resilience to contaminants, and microbial decomposition processes.

  18. Control of GHG emission at the microbial community level.

    Science.gov (United States)

    Insam, H; Wett, B

    2008-01-01

    All organic material eventually is decomposed by microorganisms, and considerable amounts of C and N end up as gaseous metabolites. The emissions of greenhouse relevant gases like carbon dioxide, methane and nitrous oxides largely depend on physico-chemical conditions like substrate quality or the redox potential of the habitat. Manipulating these conditions has a great potential for reducing greenhouse gas emissions. Such options are known from farm and waste management, as well as from wastewater treatment. In this paper examples are given how greenhouse gas production might be reduced by regulating microbial processes. Biogas production from manure, organic wastes, and landfills are given as examples how methanisation may be used to save fossil fuel. Methane oxidation, on the other hand, might alleviate the problem of methane already produced, or the conversion of aerobic wastewater treatment to anaerobic nitrogen elimination through the anaerobic ammonium oxidation process might reduce N2O release to the atmosphere. Changing the diet of ruminants, altering soil water potentials or a change of waste collection systems are other measures that affect microbial activities and that might contribute to a reduction of carbon dioxide equivalents being emitted to the atmosphere.

  19. Patterns in the composition of microbial communities from a subtropical river: effects of environmental, spatial and temporal factors.

    Directory of Open Access Journals (Sweden)

    Lemian Liu

    Full Text Available Microbes are key components of aquatic ecosystems and play crucial roles in global biogeochemical cycles. However, the spatiotemporal dynamics of planktonic microbial community composition in riverine ecosystems are still poorly understood. In this study, we used denaturing gradient gel electrophoresis of PCR-amplified 16S and 18S rRNA gene fragments and multivariate statistical methods to explore the spatiotemporal patterns and driving factors of planktonic bacterial and microbial eukaryotic communities in the subtropical Jiulong River, southeast China. Both bacterial and microbial eukaryotic communities varied significantly in time and were spatially structured according to upper stream, middle-lower stream and estuary. Among all the environmental factors measured, water temperature, conductivity, PO4-P and TN/TP were best related to the spatiotemporal distribution of bacterial community, while water temperature, conductivity, NOx-N and transparency were closest related to the variation of eukaryotic community. Variation partitioning, based on partial RDA, revealed that environmental factors played the most important roles in structuring the microbial assemblages by explaining 11.3% of bacterial variation and 17.5% of eukaryotic variation. However, pure spatial factors (6.5% for bacteria and 9.6% for eukaryotes and temporal factors (3.3% for bacteria and 5.5% for eukaryotes also explained some variation in microbial distribution, thus inherent spatial and temporal variation of microbial assemblages should be considered when assessing the impact of environmental factors on microbial communities.

  20. Farm management, not soil microbial diversity, controls nutrient loss from smallholder tropical agriculture.

    Science.gov (United States)

    Wood, Stephen A; Almaraz, Maya; Bradford, Mark A; McGuire, Krista L; Naeem, Shahid; Neill, Christopher; Palm, Cheryl A; Tully, Katherine L; Zhou, Jizhong

    2015-01-01

    Tropical smallholder agriculture is undergoing rapid transformation in nutrient cycling pathways as international development efforts strongly promote greater use of mineral fertilizers to increase crop yields. These changes in nutrient availability may alter the composition of microbial communities with consequences for rates of biogeochemical processes that control nutrient losses to the environment. Ecological theory suggests that altered microbial diversity will strongly influence processes performed by relatively few microbial taxa, such as denitrification and hence nitrogen losses as nitrous oxide, a powerful greenhouse gas. Whether this theory helps predict nutrient losses from agriculture depends on the relative effects of microbial community change and increased nutrient availability on ecosystem processes. We find that mineral and organic nutrient addition to smallholder farms in Kenya alters the taxonomic and functional diversity of soil microbes. However, we find that the direct effects of farm management on both denitrification and carbon mineralization are greater than indirect effects through changes in the taxonomic and functional diversity of microbial communities. Changes in functional diversity are strongly coupled to changes in specific functional genes involved in denitrification, suggesting that it is the expression, rather than abundance, of key functional genes that can serve as an indicator of ecosystem process rates. Our results thus suggest that widely used broad summary statistics of microbial diversity based on DNA may be inappropriate for linking microbial communities to ecosystem processes in certain applied settings. Our results also raise doubts about the relative control of microbial composition compared to direct effects of management on nutrient losses in applied settings such as tropical agriculture.

  1. Farm management, not soil microbial diversity, controls nutrient loss from smallholder tropical agriculture

    Directory of Open Access Journals (Sweden)

    Stephen A Wood

    2015-03-01

    Full Text Available Tropical smallholder agriculture supports the livelihoods of over 900 million of the world’s poorest people. This form of agriculture is undergoing rapid transformation in nutrient cycling pathways as international development efforts strongly promote greater use of mineral fertilizers to increase crop yields. These changes in nutrient availability may alter the composition of microbial communities with consequences for rates of biogeochemical processes that control nutrient losses to the environment. Ecological theory suggests that altered microbial diversity will strongly influence processes performed by relatively few microbial taxa, such as denitrification and hence nitrogen losses as nitrous oxide, a powerful greenhouse gas. Whether this theory helps predict nutrient losses from agriculture depends on the relative effects of microbial community change and increased nutrient availability on ecosystem processes. We find that mineral and organic nutrient addition to smallholder farms in Kenya alters the taxonomic and functional diversity of soil microbes. However, we find that the direct effects of farm management on both denitrification and carbon mineralization are greater than indirect effects through changes in the taxonomic and functional diversity of microbial communities. Changes in functional diversity are strongly coupled to changes in specific functional genes involved in denitrification, suggesting that it is the expression, rather than abundance, of key functional genes that can serve as an indicator of ecosystem process rates. Our results thus suggest that widely used broad summary statistics of microbial diversity based on DNA may be inappropriate for linking microbial communities to ecosystem processes in certain applied settings. Our results also raise doubts about the relative control of microbial composition compared to direct effects of management on nutrient losses in applied settings such as tropical agriculture.

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

    Directory of Open Access Journals (Sweden)

    Andreas Kronbichler

    2015-01-01

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

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

    Science.gov (United States)

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

    2008-01-01

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

  4. Microbial desalination cell with capacitive adsorption for ion migration control.

    Science.gov (United States)

    Forrestal, Casey; Xu, Pei; Jenkins, Peter E; Ren, Zhiyong

    2012-09-01

    A new microbial desalination cell with capacitive adsorption capability (cMDC) was developed to solve the ion migration problem facing current MDC systems. Traditional MDCs remove salts by transferring ions to the anode and cathode chambers, which may prohibit wastewater beneficial reuse due to increased salinity. The cMDC uses adsorptive activated carbon cloth (ACC) as the electrodes and utilizes the formed capacitive double layers for electrochemical ion adsorption. The cMDC removed an average of 69.4% of the salt from the desalination chamber through electrode adsorption during one batch cycle, and it did not add salts to the anode or cathode chamber. It was estimated that 61-82.2mg of total dissolved solids (TDS) was adsorbed to 1g of ACC electrode. The cMDC provides a new approach for salt management, organic removal, and energy production. Further studies will be conducted to optimize reactor configuration and achieve in situ electrode regeneration.

  5. Heart Disease Risk Factors You Can Control

    Science.gov (United States)

    ... can control the following risk factors by making lifestyle changes. Your doctor might also suggest medicine to help control some risk factors, such as high blood pressure or high cholesterol. Poor blood cholesterol (koh-LESS-tur-ol) and triglyceride ( ...

  6. Microbial carbon recycling - an underestimated process controlling soil carbon dynamics - Part 1: A long-term laboratory incubation experiment

    Science.gov (United States)

    Basler, A.; Dippold, M.; Helfrich, M.; Dyckmans, J.

    2015-10-01

    Independent of its chemical structure carbon (C) persists in soil for several decades, controlled by stabilization and recycling. To disentangle the importance of the two factors on the turnover dynamics of soil sugars, an important compound of soil organic matter (SOM), a 3-year incubation experiment was conducted on a silty loam soil under different types of land use (arable land, grassland and forest) by adding 13C-labelled glucose. The compound-specific isotope analysis of soil sugars was used to examine the dynamics of different sugars during incubation. Sugar dynamics were dominated by a pool of high mean residence times (MRT) indicating that recycling plays an important role for sugars. However, this was not substantially affected by soil C content. Six months after label addition the contribution of the label was much higher for microbial biomass than for CO2 production for all examined land use types, corroborating that substrate recycling was very effective within the microbial biomass. Two different patterns of tracer dynamics could be identified for different sugars: while fucose and mannose showed highest label contribution at the beginning of the incubation with a subsequent slow decline, galactose and rhamnose were characterized by slow label incorporation with subsequently constant levels, which indicates that recycling is dominating the dynamics of these sugars. This may correspond to (a) different microbial growing strategies (r and K-strategist) or (b) location within or outside the cell membrane (lipopolysaccharides vs. exopolysaccharides) and thus be subject of different re-use within the microbial food web. Our results show how the microbial community recycles substrate very effectively and that high losses of substrate only occur during initial stages after substrate addition. This study indicates that recycling is one of the major processes explaining the high MRT observed for many SOM fractions and thus is crucial for understanding the

  7. Photochemical Control of Organic Carbon Availability to Coastal Microbial Communities

    Science.gov (United States)

    Miller, W. L.; Reader, H. E.; Powers, L. C.

    2010-12-01

    Chromophoric dissolved organic matter (CDOM) is the fraction of dissolved organic matter that absorbs solar radiation. In terrestrially influenced locations high concentrations of CDOM help to shield the biological community from harmful UV radiation. Although CDOM is largely biologically refractory in nature, photochemistry has the potential to transform biologically refractory carbon into more biolabile forms. Studies suggest that in marine systems, the effect of UVR on carbon availability and subsequent bacterial production varies widely, ranging from a +200% increase to a -75% decrease (Mopper and Kieber, 2002). Evidence suggests that the largely negative or “no-effect” samples are from oligotrophic waters and that terrestrially influenced samples experience a more positive effect on the biolability of carbon after irradiation. To quantify the effects of photochemistry on the biolability of DOC in a terrestrially influenced system, a quarterly sampling effort was undertaken at three estuarine locations off the coast of Georgia, USA for a total of 14 apparent quantum yield (AQY) determinations. Large expanses of salt marsh on the coast of Georgia, create a large non-point source of DOC to the coastal ocean. Sapelo Sound, the northernmost sampling site, is dominated by offshore waters and receives little to no freshwater input throughout the year. Altamaha Sound, the southernmost sampling site, is strongly influenced by the Altamaha River, which drains the largest watershed in the state of Georgia. Doboy Sound, situated between these two sites, is largely marine dominated but is influenced by fresh water during periods of high river flow. Each sample was 0.2um filter-sterilized before irradiation in a Suntest Solar Simulator; using optical filters to create 7 distinct radiance spectra in 15 samples for determination of AQY spectra for release of biolabile DOC. Irradiated samples were consequently inoculated with the natural microbial community concentrated

  8. Control of Microbial Growth in Alginate/Polydopamine Core/Shell Microbeads.

    Science.gov (United States)

    Kim, Beom Jin; Park, Taegyun; Park, So-Young; Han, Sang Woo; Lee, Hee-Seung; Kim, Yang-Gyun; Choi, Insung S

    2015-10-01

    Microbial microencapsulation not only protects microorganisms from harmful environments by physically isolating them from the outside media but also has the potential to tailor the release profile of the encapsulated cells. However, the microbial release has not yet been controlled tightly, leading to undesired detrimental exposure of microorganisms to the outside. In this work, we suggest a simple method for controlling the cell release by suppressing the microbial growth in the microbeads. Alginate microbeads, encapsulating yeast cells, were coated with ultrathin but robust polydopamine shells, and the resulting core/shell structures effectively reduced the growth rate, while maintaining the cell viability. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Strategies to diagnose and control microbial souring in natural gas storage reservoirs and produced water systems

    Energy Technology Data Exchange (ETDEWEB)

    Morris, E.A.; Derr, R.M.; Pope, D.H.

    1995-12-31

    Hydrogen sulfide production (souring) in natural gas storage reservoirs and produced water systems is a safety and environmental problem that can lead to operational shutdown when local hydrogen sulfide standards are exceeded. Systems affected by microbial souring have historically been treated using biocides that target the general microbial community. However, requirements for more environmentally friendly solutions have led to treatment strategies in which sulfide production can be controlled with minimal impact to the system and environment. Some of these strategies are based on microbial and/or nutritional augmentation of the sour environment. Through research sponsored by the Gas Research Institute (GRI) in Chicago, Illinois, methods have been developed for early detection of microbial souring in natural gas storage reservoirs, and a variety of mitigation strategies have been evaluated. The effectiveness of traditional biocide treatment in gas storage reservoirs was shown to depend heavily on the methods by which the chemical is applied. An innovative strategy using nitrate was tested and proved ideal for produced water and wastewater systems. Another strategy using elemental iodine was effective for sulfide control in evaporation ponds and is currently being tested in microbially sour natural gas storage wells.

  10. Effect of fixed orthodontic appliances on salivary microbial parameters at 6 months : a controlled observational study

    NARCIS (Netherlands)

    Maret, Delphine; Marchal-Sixou, Christine; Vergnes, Jean-Noel; Hamel, Olivier; Georgelin-Gurgel, Marie; Van Der Sluis, Lucas; Sixou, Michel

    2014-01-01

    Objective: The aim of this study was to assess the microbial changes in children with fixed orthodontic appliances compared with a control group of children without orthodontic treatment. Material and Methods: Ninety-five children, aged between 12 and 16 years, participated in this study. Forty-eigh

  11. Aschersonia aleyrodis as a microbial control agent of greenhouse whitefly.

    NARCIS (Netherlands)

    Fransen, J.J.

    1987-01-01

    Various aspects of the development of the entomopathogenic fungus Aschersoniaaleyrodis as a control agent of greenhouse whitefly, Trialeurodesvaporariorum , were investigated. For control of greenhouse whitefly in tomato crops the parasitoid Encarsiaformosa

  12. Top-down control of carbon sequestration: grazing affects microbial structure and function in salt marsh soils.

    Science.gov (United States)

    Mueller, Peter; Granse, Dirk; Nolte, Stefanie; Do, Hai Thi; Weingartner, Magdalena; Hoth, Stefan; Jensen, Kai

    2017-03-20

    Tidal wetlands have been increasingly recognized as long-term carbon sinks in recent years. Work on carbon sequestration and decomposition processes in tidal wetlands focused so far mainly on effects of global-change factors such as sea-level rise and increasing temperatures. However, little is known about effects of land use, such as livestock grazing, on organic matter decomposition and ultimately carbon sequestration. The present work aims at understanding the mechanisms by which large herbivores can affect organic matter decomposition in tidal wetlands. This was achieved by studying both direct animal-microbe interactions and indirect animal-plant-microbe interactions in grazed and ungrazed areas of two long-term experimental field sites at the German North Sea coast. We assessed bacterial and fungal gene abundance using quantitative PCR, as well as the activity of microbial exo-enzymes by conducting fluorometric assays. We demonstrate that grazing can have a profound impact on the microbial community structure of tidal wetland soils, by consistently increasing the fungi-to-bacteria ratio by 38-42%, and therefore potentially exerts important control over carbon turnover and sequestration. The observed shift in the microbial community was primarily driven by organic matter source, with higher contributions of recalcitrant autochthonous (terrestrial) vs. easily degradable allochthonous (marine) sources in grazed areas favoring relative fungal abundance. We propose a novel and indirect form of animal-plant-microbe interaction: top-down control of aboveground vegetation structure determines the capacity of allochthonous organic matter trapping during flooding and thus the structure of the microbial community. Furthermore, our data provide the first evidence that grazing slows down microbial exo-enzyme activity and thus decomposition through changes in soil redox chemistry. Activities of enzymes involved in C cycling were reduced by 28-40%, while activities of

  13. Environmental factors influencing the structural dynamics of soil microbial communities during assisted phytostabilization of acid-generating mine tailings: a mesocosm experiment.

    Science.gov (United States)

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

    2014-12-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

  15. Control of microbial corrosion using coatings and natural additives

    Energy Technology Data Exchange (ETDEWEB)

    Al-Darbi, M.M.; Muntasser, Z.M.; Tango, M.; Islam, M.R.

    2002-11-01

    One of the major concerns in the oil and gas industry is corrosion. Microbial-influenced corrosion (MIC) can be defined as the deterioration of metals by natural processes directly or indirectly related to the activity of microorganisms. MIC affects many industries, such as petrochemical, ships and marine structures, power generating, aircraft fuel systems, waste water facilities, cooling water systems, process industries, paper mills, and water supply and distribution systems. In this study, the influence of sulfate-reducing bacteria (SRB), grown in a lactate/ sulfate culture medium, on the corrosion of both uncoated and coated mild steel was evaluated in the presence and absence of natural additives. To achieve this, an oil based coating (alkyd) was used with and without the addition of natural additives to protect mild steel in a sulfate-reducing bacteria environment. Another objective of this study was to investigate the effects of SRB and/or their metabolites on the used coatings and the adverse effects of those coatings and additives on biofilm formation and bacteria growth rate. In this paper, 2 natural additives were identified for effective MIC protection. Natural products were selected based on the environmental appeal of the products. Two additives, derived from olive oil and Manhaden fish oil, were found to be effective in reducing MIC. In general, 2-3% of a natural additive was deemed adequate for effective MIC protection. Bacteria populations were counted at the beginning and at the end of the tests using the plate count method. After immersing the different coupons for 3 months in the SRB medium, it was noticed that the number of bacteria and their colonies were highly affected by both the environment and the used coating systems. A series of corrosion tests was performed to study the effectiveness of various natural additives. Visual observations, scanning electron microscopy (SEM) analyses, and computer image analyzer techniques were used to study

  16. Microbial responses to multi-factor climate change: Effects on soil enzymes

    Directory of Open Access Journals (Sweden)

    J Megan Steinweg

    2013-06-01

    Full Text Available The activities of extracellular enzymes, the proximate agents of decomposition in soils, are known to depend strongly on temperature, but less is known about how they respond to changes in precipitation patterns, and the interaction of these two components of climate change. Both enzyme production and turnover can be affected by changes in temperature and soil moisture, thus it is difficult to predict how enzyme pool size may respond to altered climate. Soils from the Boston-Area Climate Experiment, which is located in an old field (on abandoned farmland, were used to examine how climate variables affect enzyme activities and microbial biomass carbon (MBC in different seasons and in soils exposed to a combination of three levels of precipitation treatments (ambient, 150% of ambient during growing season, and 50% of ambient year-round and four levels of warming treatments (unwarmed to ~4˚C above ambient over the course of a year. Warming, precipitation and season had very little effect on potential enzyme activity. Most models assume that enzyme dynamics follow microbial biomass, because enzyme production should be directly controlled by the size and activity of microbial biomass. We observed differences among seasons and treatments in mass-specific potential enzyme activity, suggesting that this assumption is invalid. In June 2009, mass-specific potential enzyme activity, using chloroform fumigation-extraction MBC, increased with temperature, peaking under medium warming and then declining under the highest warming. This finding suggests that either enzyme production increased with temperature or turnover rates decreased. Increased maintenance costs associated with warming may have resulted in increased mass-specific enzyme activities due to increased nutrient demand. Our research suggests that allocation of resources to enzyme production could be affected by climate-induced changes in microbial efficiency and maintenance costs.

  17. Microbial contamination control in fuels and fuel systems since 1980 - a review

    Energy Technology Data Exchange (ETDEWEB)

    Passman, Frederick J. [Biodeterioration Control Associates, Inc (United States)], email: fredp@biodeterioration-control.com

    2011-07-01

    This paper presents a review of microbial contamination control in fuel and fuel systems. Some examples of the biodeterioration of components of fuel systems are given. Root cause analysis (RCA) and modeling can help in condition monitoring of fuel systems. RCA is a systematic process that starts after symptoms become apparent and facilitates improvement. Modeling, by contrast, starts before the problem occurs and the objective is to improve understanding of the process. Some of the different areas creating risk due to the process are climate, microbiology, chemistry, maintenance, and engineering. Condition monitoring is explained in detail, using representative samples. Contamination control plays a very important role. Various aspects of microbial contamination control are design, inventory control, house keeping and remediation. These aspects are explained in detail, using various examples. Since the deterioration cost involved is very high, its is important to avoid this problem by reducing the quantity of water used and using better risk assessment models.

  18. Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids. Part I: effects on growth performance, microbial populations, and immune status.

    Science.gov (United States)

    Walsh, M C; Rostagno, M H; Gardiner, G E; Sutton, A L; Richert, B T; Radcliffe, J S

    2012-01-01

    Pigs (n = 88) weaned at 19 ± 2 d of age were used in a 14-d study to evaluate the effects of water-delivered direct-fed microbials (DFM) or organic acids on growth, immune status, Salmonella infection and shedding, and intestinal microbial populations after intranasal inoculation of Salmonella Typhimurium (10(10) cfu/pig). Pigs were challenged with Salmonella 6 d after commencement of water treatments. Treatments were 1) control diet; 2) control diet + DFM (Enterococcus faecium, Bacillus subtilis, and Bacillus licheniformis) in drinking water at 10(9) cfu/L for each strain of bacteria; 3) control diet + an organic acid-based blend (predominantly propionic, acetic, and benzoic acid) in drinking water at 2.58 mL/L; and 4) control diet + 55 mg/kg of carbadox. Serum samples were taken on d 6, 8, 10, and 14 for determination of tumor necrosis factor α (TNFα) concentrations. Fecal samples were taken on d 0, 5, 7, and 11 for determination of Salmonella shedding and enumeration of coliforms. Pigs were euthanized on d 6, 8, 10, and 14. Intestinal and cecal tissue and digesta and mesenteric lymph nodes were sampled and analyzed for Salmonella. Duodenal, jejunal, and ileal mucosal scrapings were sampled for measurement of mucosal TNFα concentrations. Water delivery of DFM prevented a decline in ADG on d 2 to 6 postchallenge compared with the negative control (P treatment group on d 2 postinfection compared with the negative control and acid treatment groups. However, Salmonella prevalence in the feces, gastrointestinal tract, or lymph nodes was not affected by water delivery of acids or DFM. Serum and mucosal TNFα concentrations were not affected by treatment throughout the study with the exception of ileal concentrations on d 4 postchallenge, which were greater in the negative control group compared with all other treatments (P treatment that reduced Salmonella prevalence and this was localized to the cecum on d 8 postinfection. In conclusion, the DFM and organic acid

  19. Progression of natural attenuation processes at a crude oil spill site: II. Controls on spatial distribution of microbial populations.

    Science.gov (United States)

    Bekins, B A; Cozzarelli, I M; Godsy, E M; Warren, E; Essaid, H I; Tuccillo, M E

    2001-12-15

    A multidisciplinary study of a crude-oil contaminated aquifer shows that the distribution of microbial physiologic types is strongly controlled by the aquifer properties and crude oil location. The microbial populations of four physiologic types were analyzed together with permeability, pore-water chemistry, nonaqueous oil content, and extractable sediment iron. Microbial data from three vertical profiles through the anaerobic portion of the contaminated aquifer clearly show areas that have progressed from iron-reduction to methanogenesis. These locations contain lower numbers of iron reducers, and increased numbers of fermenters with detectable methanogens. Methanogenic conditions exist both in the area contaminated by nonaqueous oil and also below the oil where high hydrocarbon concentrations correspond to local increases in aquifer permeability. The results indicate that high contaminant flux either from local dissolution or by advective transport plays a key role in determining which areas first become methanogenic. Other factors besides flux that are important include the sediment Fe(II) content and proximity to the water table. In locations near a seasonally oscillating water table, methanogenic conditions exist only below the lowest typical water table elevation. During 20 years since the oil spill occurred, a laterally continuous methanogenic zone has developed along a narrow horizon extending from the source area to 50-60 m downgradient. A companion paper [J. Contam. Hydrol. 53, 369-386] documents how the growth of the methanogenic zone results in expansion of the aquifer volume contaminated with the highest concentrations of benzene, toluene, ethylbenzene, and xylenes.

  20. Denitrification in a large river: consideration of geomorphic controls on microbial activity and community structure.

    Science.gov (United States)

    Tatariw, Corianne; Chapman, Elise L; Sponseller, Ryan A; Mortazavi, Behzad; Edmonds, Jennifer W

    2013-10-01

    Ecological theory argues that the controls over ecosystem processes are structured hierarchically, with broader-scale drivers acting as constraints over the interactions and dynamics at nested levels of organization. In river ecosystems, these interactions may arise from broadscale variation in channel form that directly shapes benthic habitat structure and indirectly constrains resource supply and biological activity within individual reaches. To evaluate these interactions, we identified sediment characteristics, water chemistry, and denitrifier community structure as factors influencing benthic denitrification rates in a sixth-order river that flows through two physiographic provinces and the transitional zone between them, each with distinct geomorphological properties. We found that denitrification rates tracked spatial changes in sediment characteristics and varied seasonally with expected trends in stream primary production. Highest rates were observed during the spring and summer seasons in the physiographic province dominated by fine-grained sediments, illustrating how large-scale changes in river structure can constrain the location of denitrification hotspots. In addition, nirS and nirK community structure each responded differently to variation in channel form, possibly due to changes in dissolved oxygen and organic matter supply. This shift in denitrifier community structure coincident with higher rates of N removal via denitrification suggests that microbial community structure may influence biogeochemical processes.

  1. Graphite anode surface modification with controlled reduction of specific aryl diazonium salts for improved microbial fuel cells power output.

    Science.gov (United States)

    Picot, Matthieu; Lapinsonnière, Laure; Rothballer, Michael; Barrière, Frédéric

    2011-10-15

    Graphite electrodes were modified with reduction of aryl diazonium salts and implemented as anodes in microbial fuel cells. First, reduction of 4-aminophenyl diazonium is considered using increased coulombic charge density from 16.5 to 200 mC/cm(2). This procedure introduced aryl amine functionalities at the surface which are neutral at neutral pH. These electrodes were implemented as anodes in "H" type microbial fuel cells inoculated with waste water, acetate as the substrate and using ferricyanide reduction at the cathode and a 1000 Ω external resistance. When the microbial anode had developed, the performances of the microbial fuel cells were measured under acetate saturation conditions and compared with those of control microbial fuel cells having an unmodified graphite anode. We found that the maximum power density of microbial fuel cell first increased as a function of the extent of modification, reaching an optimum after which it decreased for higher degree of surface modification, becoming even less performing than the control microbial fuel cell. Then, the effect of the introduction of charged groups at the surface was investigated at a low degree of surface modification. It was found that negatively charged groups at the surface (carboxylate) decreased microbial fuel cell power output while the introduction of positively charged groups doubled the power output. Scanning electron microscopy revealed that the microbial anode modified with positively charged groups was covered by a dense and homogeneous biofilm. Fluorescence in situ hybridization analyses showed that this biofilm consisted to a large extent of bacteria from the known electroactive Geobacter genus. In summary, the extent of modification of the anode was found to be critical for the microbial fuel cell performance. The nature of the chemical group introduced at the electrode surface was also found to significantly affect the performance of the microbial fuel cells. The method used for

  2. Treatment of angular cheilitis. The significance of microbial analysis, antimicrobial treatment, and interfering factors.

    Science.gov (United States)

    Ohman, S C; Jontell, M

    1988-10-01

    This prospective study evaluated the significance of microbial analysis and antimicrobial treatment for the cure of angular cheilitis. Furthermore, various etiologic factors were investigated for their relative effect on the healing process. The study included 1) an open trial with 50 patients infected by Candida albicans and/or Staphylococcus aureus, and 2) an intraindividual comparison of eight patients with bilateral lesions infected by Candida albicans as the only detected pathogen. After a base-line examination the patients received ointments containing nystatin and/or fusidic acid, on the basis of the outcome of an initial microbial analysis. The patients were evaluated clinically, photographed, and examined for microorganisms at different time intervals. Ninety-six per cent of the patients who participated in the open trial had no sign of infection after 42 days of treatment. Lesions in the double-blind study, treated with nystatin, were healed after 28 days, whereas lesions that received placebo persisted throughout the treatment period. Increasing age, dry skin, and extended skinfolds at the corner of the mouth were factors closely related to the length of the healing process.

  3. THE ROLE OF BACTERIAL FACTOR AND IMMUNOLOGICAL СHANGES IN NONINFECTIOUS DISEASES OF MICROBIAL ORIGIN

    Directory of Open Access Journals (Sweden)

    Korniychuk O.P.

    2015-05-01

    lipopolysaccharide of own and intact E. coli and isolates from control persons. Results and discussion. LPS isolated from E. coli strains isolated from patients with different clinical groups showed varying effects on the immune response. It was established that cytokines are produced to stimulation by antigens of own microflora more active than by the intact lipopolysaccharide. Moreover, it is typical for both proinflammatory and problastomic cytokines. The highest activity was found in lipopolysaccharide bacteria isolated in patients with Crohn's disease, for the pathogenesis of which immunopathological component was proved and which can accordingly cause certain features of the disease. Trigger factors for developing reactive arthritis (ReA microorganisms with obligate (Chlamydia, some viruses or optional (Yersinia, Shigella, mycoplasma, Campylobacteria, salmonella parasitism are considered to be. Research of subpopulation spectrum of blood lymphocytes of 20 persons with ReA was conducted. Slight decrease in absolute quantity of natural killers was registered. Thus, the relative index CD16 + 56 + in patients with ReA was 11,8 ± 1,21% to 14,92 ± 1,13 in almost healthy individuals. However, some activation of suppressor affects the immune-regulatory index (IRI. Its amount is 1.74, which generally remains within normal limits, but is 21.8% lower than IRI of control group. Conclusion. Research of subpopulation composition of Tand B-chains of immunity at ReA to some extent confirm the theory of arthritogenic peptide of the disease development, according to which in the background of Tsuppressors activation, induced by microbial triggers, a weakening of cellular immunity occurs, inflammatory reactions with the emergence of autoimmune background develops, that in case of involving muscle and bone system leads to ReA development. In the acute stage of the disease with signs of inflammation it is appropriate to conduct antimicrobial therapy as with ReA and with diseases of the colon

  4. Causal Factors in Genome Control

    NARCIS (Netherlands)

    O'Duibhir, E.

    2015-01-01

    The aim of this thesis is to study how genes are switched on and off in a coordinated way across an entire genome. In order to do this yeast is used as a model organism. The mechanisms that control gene expression in yeast are very similar to those of human cells. Chapter 1 provides a general introd

  5. Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges

    KAUST Repository

    Prest, Emmanuelle I.

    2016-02-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g., development of opportunistic pathogens), aesthetic (e.g., deterioration of taste, odor, color) or operational (e.g., fouling or biocorrosion of pipes) problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors, such as (i) type and concentration of available organic and inorganic nutrients, (ii) type and concentration of residual disinfectant, (iii) presence of predators, such as protozoa and invertebrates, (iv) environmental conditions, such as water temperature, and (v) spatial location of microorganisms (bulk water, sediment, or biofilm). Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability) in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i) existing knowledge on biological stability controlling factors and (ii) how these factors are affected by drinking water production and distribution conditions. In addition, (iii) the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discussed, how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order

  6. Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges

    Science.gov (United States)

    Prest, Emmanuelle I.; Hammes, Frederik; van Loosdrecht, Mark C. M.; Vrouwenvelder, Johannes S.

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g., development of opportunistic pathogens), aesthetic (e.g., deterioration of taste, odor, color) or operational (e.g., fouling or biocorrosion of pipes) problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors, such as (i) type and concentration of available organic and inorganic nutrients, (ii) type and concentration of residual disinfectant, (iii) presence of predators, such as protozoa and invertebrates, (iv) environmental conditions, such as water temperature, and (v) spatial location of microorganisms (bulk water, sediment, or biofilm). Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability) in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i) existing knowledge on biological stability controlling factors and (ii) how these factors are affected by drinking water production and distribution conditions. In addition, (iii) the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discussed, how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order

  7. Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges.

    Science.gov (United States)

    Prest, Emmanuelle I; Hammes, Frederik; van Loosdrecht, Mark C M; Vrouwenvelder, Johannes S

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g., development of opportunistic pathogens), aesthetic (e.g., deterioration of taste, odor, color) or operational (e.g., fouling or biocorrosion of pipes) problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors, such as (i) type and concentration of available organic and inorganic nutrients, (ii) type and concentration of residual disinfectant, (iii) presence of predators, such as protozoa and invertebrates, (iv) environmental conditions, such as water temperature, and (v) spatial location of microorganisms (bulk water, sediment, or biofilm). Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability) in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i) existing knowledge on biological stability controlling factors and (ii) how these factors are affected by drinking water production and distribution conditions. In addition, (iii) the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discussed, how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order

  8. Biological stability of drinking water: controlling factors, methods and challenges

    Directory of Open Access Journals (Sweden)

    Emmanuelle ePrest

    2016-02-01

    Full Text Available Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g. development of opportunistic pathogens, aesthetic (e.g. deterioration of taste, odour, colour or operational (e.g. fouling or biocorrosion of pipes problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors such as (i type and concentration of available organic and inorganic nutrients, (ii type and concentration of residual disinfectant, (iii presence of predators such as protozoa and invertebrates, (iv environmental conditions such as water temperature, and (v spatial location of microorganisms (bulk water, sediment or biofilm. Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i existing knowledge on biological stability controlling factors and (ii how these factors are affected by drinking water production and distribution conditions. In addition, (iii the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discuss how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order to

  9. Microbial pathogen control in the beef chain: recent research advances.

    Science.gov (United States)

    Buncic, Sava; Nychas, George-John; Lee, Michael R F; Koutsoumanis, Kostas; Hébraud, Michel; Desvaux, Mickaël; Chorianopoulos, Nikos; Bolton, Declan; Blagojevic, Bojan; Antic, Dragan

    2014-07-01

    Within a recent EU research project ("ProSafeBeef"), research on foodborne pathogens in the beef chain was conducted by using a longitudinally integrated (fork-to-farm) approach. There is not any "single intervention-single chain point" combination by which the pathogens would be reliably and entirely eliminated from the chain resulting in total prevention of pathogens in beef and products thereof at the consumption time. Rather, a range of control interventions have to be applied at multiple points of the chain, so to achieve an acceptable, ultimate risk reduction. Various novel interventions were developed and evaluated during the project, and are briefly summarized in this paper. They include on-farm measures, risk categorisation of cattle presented for slaughter, hygiene-based measures and antimicrobial treatments applied on hides and/or carcasses during cattle slaughter, those applied during beef processing-storage-distribution, use of Time Temperature Integrator-based indicators of safety, and effective sanitation of surfaces. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Evaluation of an additive efficacy in broiler litter microbial level control in field: preliminary results

    Directory of Open Access Journals (Sweden)

    Matteo Pennacchi

    2010-01-01

    Full Text Available The present study was conducted to evaluate in field the efficacy of an additive (SOP® C POULTRY, as an agent for the control of micro-organisms in broiler litter. The Total aerobic Microbial Count (TMC, Staphylococcus species (spp., Coliforms, and Salmonella spp. in broiler litter samples of both the Houses, 2 (H2 and 3 (H3, were determined, and also at the end of each cycle the mortality rate was recorded. The results showed significant reduction of all the microbial counts: P= 0.0078 (CMT, 0,0021 (Staphylococcus spp. and 0.0541 (Coliforms, and mortality (P= 0.00106 in treated litter samples H2 and the control H3.

  11. Current knowledge on groundwater microbial pathogens and their control

    Science.gov (United States)

    Macler, Bruce A.; Merkle, Jon C.

    Those who drink groundwater that has not been disinfected are at increased risk of infection and disease from pathogenic microorganisms. Recent studies have shown that up to half of all US drinking-water wells tested had evidence of fecal contamination. A significant fraction of all waterborne disease outbreaks is associated with groundwater. An estimated 750,000 to 5.9million illnesses per year result from contaminated groundwaters in the US. Mortality from these illnesses may be 1400-9400 deaths per year. Control of these pathogens starts with source-water protection activities to prevent fecal contamination of aquifers and wells. These include assessment of wellhead vulnerability to fecal contamination and correction of identified deficiencies. Correction may include control of sources or rehabilitation of the well itself. Disinfection can serve as a useful barrier and is recommended as a prudent public-health policy for all groundwater systems. Ceux qui boivent une eau souterraine non désinfectée présentent un risque accru d'infection et de maladie par des germes pathogènes. De récentes études ont montré que près de la moitié de tous les puits américains testés, captés pour l'eau potable, sont soumis à une contamination fécale. Une fraction significative de l'ensemble des premières manifestations de maladies liées à l'eau est associée aux eaux souterraines. On estime qu'entre 750 000 et 5,9millions de personnes sont malades chaque année aux États-Unis à cause d'eaux souterraines polluées. La mortalité parmi ces malades doit ètre de l'ordre de 1400 à 9400 décès par an. La protection contre ces germes pathogènes commence avec des mesures prises au niveau du captage pour empècher la pollution des aquifères et des puits. Celles-ci comprennent une évaluation de la vulnérabilité des tètes de puits à la pollution fécale et une correction des insuffisances mises en évidence. Cette correction peut comprendre une maîtrise des sources

  12. Review of microbial responses to abiotic environmental factors in the context of the proposed Yucca Mountain repository

    Energy Technology Data Exchange (ETDEWEB)

    Meike, A. [Lawrence Livermore National Lab., Livermore, CA (United States); Stroes-Gascoyne, S

    2000-10-01

    A workshop on Microbial Activities at Yucca Mountain (May 1995, Lafayette, CA) was held with the intention to compile information on all pertinent aspects of microbial activity for application to a potential repository at Yucca Mountain. The findings of this workshop set off a number of efforts intended to eventually incorporate the impacts of microbial behaviour into performance assessment models. One effort was to expand an existing modelling approach to include the distinctive characteristics of a repository at Yucca Mountain (e.g., unsaturated conditions and a significant thermal load). At the same time, a number of experimental studies were initiated as well as a compilation of relevant literature to more thoroughly study the physical, chemical and biological parameters that would affect microbial activity under Yucca Mountain-like conditions. This literature search (completed in 1996) is the subject of the present document. The collected literature can be divided into four categories, 1) abiotic factors, 2) community dynamics and in-situ considerations, 3) nutrient considerations and 4) transport of radionuclides. The complete bibliography (included in Appendix A) represents a considerable resource, but is too large to be discussed in one document. Therefore, the present report focuses on the first category, abiotic factors, and a discussion of these factors in order to facilitate the development of a model for Yucca Mountain. The first part of the report (Chapters 1-3) is a review of general microbial states, phases and requirements for growth, conditions for 'normal growth' and other types of growth, survival strategies and cell death. It contains primarily well-established ideas in microbiology. Microbial capabilities for survival and adaptation to environmental changes are examined because a repository placed at Yucca Mountain would have two effects. First, the natural environment would be perturbed by the excavation and construction of the

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

    Science.gov (United States)

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

    2011-04-01

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

  14. Factors Influencing Microbial Carbon Emission Potential from Wetland Sediments and its Relation to Surface- and Plot-Scale Measurements

    Science.gov (United States)

    Brooker, M.; Bohrer, G.; Mouser, P. J.

    2012-12-01

    Wetlands provide valuable ecosystem services by sequestering carbon dioxide from the atmosphere and serving as a sink for atmospheric nitrogen export. They are often constructed as buffers between agriculture lands and drainage channels to improve runoff water quality from elevated nutrient loading (e.g. nitrate-N). Unfortunately, carbon sequestration and denitrification in wetlands come with the tradeoff of increased production of methane, another more potent green house gas. Existing models correlate methane emission rates to increased temperature; however, surface- and plot-scale measurements show little or weak relationships between these factors at the field scale. This study examines the relationship of several environmental factors - temperature, zone location, and microbial community - to methane emissions under controlled laboratory conditions. Water and sediments collected from two depths (0-6" and 6-12") and four distinct biomes (open water and three distinct emergent macrophyte covers) were used to prepare anaerobic microcosms at two different temperatures (20°C and 30°C). Headspace gas (methane, carbon dioxide), water chemistry, and microbial community composition were analyzed over the course of several months. We observed: 1) an increase in methane emission potential with higher temperature; 2) higher levels of methane produced from shallower sediments; 3) differential production of methane versus carbon dioxide depending upon biome; and 4) variations in bacterial and archaeal diversity relating to methane production rates. This data helps provide upper limit estimates for methane emissions from wetlands by methanogenic Archaea and informs our ability to better parameterize biogeochemical and atmospheric models of these systems.

  15. Modelling highly variable environmental factors to assess potential microbial respiration in complex floodplain landscapes

    Science.gov (United States)

    Tritthart, Michael; Welti, Nina; Bondar-Kunze, Elisabeth; Pinay, Gilles; Hein, Thomas; Habersack, Helmut

    2011-01-01

    The hydrological exchange conditions strongly determine the biogeochemical dynamics in river systems. More specifically, the connectivity of surface waters between main channels and floodplains is directly controlling the delivery of organic matter and nutrients into the floodplains, where biogeochemical processes recycle them with high rates of activity. Hence, an in-depth understanding of the connectivity patterns between main channel and floodplains is important for the modelling of potential gas emissions in floodplain landscapes. A modelling framework that combines steady-state hydrodynamic simulations with long-term discharge hydrographs was developed to calculate water depths as well as statistical probabilities and event durations for every node of a computation mesh being connected to the main river. The modelling framework was applied to two study sites in the floodplains of the Austrian Danube River, East of Vienna. Validation of modelled flood events showed good agreement with gauge readings. Together with measured sediment properties, results of the validated connectivity model were used as basis for a predictive model yielding patterns of potential microbial respiration based on the best fit between characteristics of a number of sampling sites and the corresponding modelled parameters. Hot spots of potential microbial respiration were found in areas of lower connectivity if connected during higher discharges and areas of high water depths. PMID:27667961

  16. Microbial control on decomposition of radionuclides-containing oily waste in soil

    Science.gov (United States)

    Selivanovskaya, Svetlana; Galitskaya, Polina

    2014-05-01

    The oily wastes are formed annually during extraction, refinement, and transportation of the oil and may cause pollution of the environment. These wastes contain different concentrations of waste oil (40-60%), waste water (30-90%), and mineral particles (5-40%). Some oily wastes also contain naturally occurring radionuclides which were incorporated by water that was pumped up with the oil. For assessment of the hazard level of waste treated soil, not only measurements of contaminants content are needed, because bioavailability of oily components varies with hydrocarbon type, and soil properties. As far as namely microbial communities control the decomposition of organic contaminants, biological indicators have become increasingly important in hazard assessment and the efficiency of remediation process. In this study the decomposition of radionuclides-containing oily waste by soil microbial communities were estimated. Waste samples collected at the Tikchonovskii petroleum production yard (Tatarstan, Russia) were mixed with Haplic greyzem soil at ratio 1:4 and incubated for 120 days. During incubation period, the total hydrocarbon content of the soil mixed with the waste reduced from 156 ± 48 g kg-1 to 54 ± 8 g kg-1 of soil. The concentrations of 226Ra and 232Th were found to be 643 ± 127, 254 ± 56 Bq kg-1 and not changed significantly during incubation. Waste application led to a soil microbial biomass carbon decrease in comparison to control (1.9 times after 1 day and 1.3 times after 120 days of incubation). Microbial respiration increased in the first month of incubation (up to 120% and 160% of control after 1 and 30 days, correspondingly) and decreased to the end of incubation period (74% of control after 120 days). Structure of bacterial community in soil and soil/waste mixture was estimated after 120 days of incubation using SSCP method. The band number decreased in contaminated soil in comparison to untreated soil. Besides, several new dominant DNA

  17. Variability of the microbial abundance of a kefir grain starter cultivated in partially controlled conditions

    Directory of Open Access Journals (Sweden)

    Oger R.

    2005-01-01

    Full Text Available The variability of the abundance in lactobacilli, lactic acid streptococci and yeasts of a kefir grain starter cultivated in partially controlled conditions – milk renewal at room temperature and incubation at defined temperature - was quantified. Expressed by the geometric relative standard deviations of counts repeated over time, it was respectively of 28%, 443% and 35% for each of the three microbial groups. The origin of the microbial variability observed was ascribed to the heterogeneous medium developed around the grains during fermentation and, for the lactic acid streptococci, even more to the initial conditions of fermentation, probably to parameters linked to milk renewal (room temperature, waiting time at room temperature before incubation.

  18. Factors affecting the performance of microbial fuel cells for sulfur pollutants removal.

    Science.gov (United States)

    Zhao, Feng; Rahunen, Nelli; Varcoe, John R; Roberts, Alexander J; Avignone-Rossa, Claudio; Thumser, Alfred E; Slade, Robert C T

    2009-03-15

    A microbial fuel cell (MFC) has been developed for removal of sulfur-based pollutants and can be used for simultaneous wastewater treatment and electricity generation. This fuel cell uses an activated carbon cloth+carbon fibre veil composite anode, air-breathing dual cathodes and the sulfate-reducing species Desulfovibrio desulfuricans. 1.16gdm(-3) sulfite and 0.97gdm(-3) thiosulfate were removed from the wastewater at 22 degrees C, representing sulfite and thiosulfate removal conversions of 91% and 86%, respectively. The anode potential was controlled by the concentration of sulfide in the compartment. The performance of the cathode assembly was affected by the concentration of protons in the cation-exchanging ionomer with which the electrocatalyst is co-bound at the three-phase (air, catalyst and support) boundary.

  19. Geological and Geochemical Controls on Subsurface Microbial Life in the Samail Ophiolite, Oman

    Science.gov (United States)

    Rempfert, Kaitlin R.; Miller, Hannah M.; Bompard, Nicolas; Nothaft, Daniel; Matter, Juerg M.; Kelemen, Peter; Fierer, Noah; Templeton, Alexis S.

    2017-01-01

    Microbial abundance and diversity in deep subsurface environments is dependent upon the availability of energy and carbon. However, supplies of oxidants and reductants capable of sustaining life within mafic and ultramafic continental aquifers undergoing low-temperature water-rock reaction are relatively unknown. We conducted an extensive analysis of the geochemistry and microbial communities recovered from fluids sampled from boreholes hosted in peridotite and gabbro in the Tayin block of the Samail Ophiolite in the Sultanate of Oman. The geochemical compositions of subsurface fluids in the ophiolite are highly variable, reflecting differences in host rock composition and the extent of fluid-rock interaction. Principal component analysis of fluid geochemistry and geologic context indicate the presence of at least four fluid types in the Samail Ophiolite (“gabbro,” “alkaline peridotite,” “hyperalkaline peridotite,” and “gabbro/peridotite contact”) that vary strongly in pH and the concentrations of H2, CH4, Ca2+, Mg2+, NO3-, SO42-, trace metals, and DIC. Geochemistry of fluids is strongly correlated with microbial community composition; similar microbial assemblages group according to fluid type. Hyperalkaline fluids exhibit low diversity and are dominated by taxa related to the Deinococcus-Thermus genus Meiothermus, candidate phyla OP1, and the family Thermodesulfovibrionaceae. Gabbro- and alkaline peridotite- aquifers harbor more diverse communities and contain abundant microbial taxa affiliated with Nitrospira, Nitrosospharaceae, OP3, Parvarcheota, and OP1 order Acetothermales. Wells that sit at the contact between gabbro and peridotite host microbial communities distinct from all other fluid types, with an enrichment in betaproteobacterial taxa. Together the taxonomic information and geochemical data suggest that several metabolisms may be operative in subsurface fluids, including methanogenesis, acetogenesis, and fermentation, as well as the

  20. Predisposing Factors, Microbial Characteristics, and Clinical Outcome of Microbial Keratitis in a Tertiary Centre in Hong Kong: A 10-Year Experience

    Directory of Open Access Journals (Sweden)

    Alex Lap-Ki Ng

    2015-01-01

    Full Text Available Purpose. To study the risk factors, microbial profile, antibiotic susceptibility pattern, and outcome for microbial keratitis over the past 10 years in a tertiary center in Hong Kong. Methods. All cases with corneal scraping performed in Queen Mary Hospital, Hong Kong from January 2004 to December 2013 were included. Clinical outcome was defined as poor if the final visual acuity (VA was abnormal or worse than presenting VA, a major complication occurred, or therapeutic keratoplasty was required. Results. 347 scrapes were performed in the 10-year period growing 130 microorganisms (32.3% culture positive rate. Contact lens use was the commonest risk factor. The commonest isolates were coagulase-negative Staphylococcus and Pseudomonas aeruginosa. Fluoroquinolone susceptibility was tested in 47 Gram-negative bacteria with 93.6% susceptibility (100% for Pseudomonas. 90.7% of cases had good visual outcome. Multivariate logistic regression showed age (p=0.03, trauma (p=0.006, and ulcer size >3 mm (p=0.039 to be independently associated with poor outcome. Conclusion. There was no shifting trend in the isolate distribution or emergence of resistant strains in our study. Contact lens wear was the commonest risk factor, with Pseudomonas being the most frequent isolate in this group. It remained 100% susceptible to fluoroquinolones and 97% cases had good visual outcome.

  1. Controls upon microbial accessibility to soil organic matter following woody plant encroachment into grasslands

    Science.gov (United States)

    Creamer, C. A.; Boutton, T. W.; Filley, T. R.

    2009-12-01

    Woody plant encroachment (WPE) into savannas and grasslands is a global phenomenon that alters soil organic matter (SOM) dynamics through changes in litter quality and quantity, soil structure, microbial ecology, and soil hydrology. To elucidate the controls upon microbial accessibility to SOM, bulk soils from a chronosequence of progressive WPE into native grasslands at the Texas A&M Agricultural Experimental Station La Copita Research Area were incubated for one year. The quantity and stable carbon isotope composition of respired CO2, plant biopolymer chemistry in SOM, and microbial community structure were tracked. Respiration rates declined steadily over the course of the experiment with 15-25% of the total CO2 respired released in the first month of incubation. Between 8 and 18% of the total carbon was mineralized to CO2 throughout the incubation. After day 84 a significantly (p cutin and suberin, as hypothesized by others. Quantitative and isotopic comparisons of these monomers prior to and following the incubation will determine if selective compound utilization is a reason for this depletion. The results discussed herein provide important insights into the dynamics of SOM accrual with WPE as well as respiration dynamics during laboratory incubations.

  2. Metagenomes from high-temperature chemotrophic systems reveal geochemical controls on microbial community structure and function.

    Science.gov (United States)

    Inskeep, William P; Rusch, Douglas B; Jay, Zackary J; Herrgard, Markus J; Kozubal, Mark A; Richardson, Toby H; Macur, Richard E; Hamamura, Natsuko; Jennings, Ryan deM; Fouke, Bruce W; Reysenbach, Anna-Louise; Roberto, Frank; Young, Mark; Schwartz, Ariel; Boyd, Eric S; Badger, Jonathan H; Mathur, Eric J; Ortmann, Alice C; Bateson, Mary; Geesey, Gill; Frazier, Marvin

    2010-03-19

    transport is consistent with the hypothesis that geochemical parameters (e.g., pH, sulfide, Fe, O2) control microbial community structure and function in YNP geothermal springs.

  3. Metagenomes from high-temperature chemotrophic systems reveal geochemical controls on microbial community structure and function

    Energy Technology Data Exchange (ETDEWEB)

    Frank Roberto

    2010-03-01

    consistent with the hypothesis that geochemical parameters (e.g., pH, sulfide, Fe, O2) control microbial community structure and function in YNP geothermal springs.

  4. Metagenomes from high-temperature chemotrophic systems reveal geochemical controls on microbial community structure and function.

    Directory of Open Access Journals (Sweden)

    William P Inskeep

    electron transport is consistent with the hypothesis that geochemical parameters (e.g., pH, sulfide, Fe, O2 control microbial community structure and function in YNP geothermal springs.

  5. COMBINED MICROBIAL SURFACTANT-POLYMER SYSTEM FOR IMPROVED OIL MOBILITY AND CONFORMANCE CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Jorge Gabitto; Maria Barrufet

    2004-08-01

    Many domestic oil fields are facing abandonment even though they still contain two-thirds of their original oil. A significant number of these fields can yield additional oil using advanced oil recovery (AOR) technologies. To maintain domestic oil production at current levels, AOR technologies are needed that are affordable and can be implemented by independent oil producers of the future. Microbial enhanced oil recovery (MEOR) technologies have become established as cost-effective solutions for declining oil production. MEOR technologies are affordable for independent producers operating stripper wells and can be used to extend the life of marginal fields. The demonstrated versatility of microorganisms can be used to design advanced microbial systems to treat multiple production problems in complex, heterogeneous reservoirs. The proposed research presents the concept of a combined microbial surfactant-polymer system for advanced oil recovery. The surfactant-polymer system utilizes bacteria that are capable of both biosurfactant production and metabolically-controlled biopolymer production. This novel technology combines complementary mechanisms to extend the life of marginal fields and is applicable to a large number of domestic reservoirs. The research project described in this report is performed jointly by, Bio-Engineering Inc., a woman owned small business, Texas A&M University and Prairie View A&M University, a Historically Black College and University. This report describes the results of our laboratory work to grow microbial cultures and the work done on recovery experiments on core rocks. We have selected two bacterial strains capable of producing both surfactant and polymers. We have conducted laboratory experiments to determine under what conditions surfactants and polymers can be produced from one single strain. We have conduct recovery experiments to determine the performance of these strains under different conditions. Our results do not show a

  6. Dynamical Allocation of Cellular Resources as an Optimal Control Problem: Novel Insights into Microbial Growth Strategies

    Science.gov (United States)

    Giordano, Nils; Mairet, Francis; Gouzé, Jean-Luc

    2016-01-01

    Microbial physiology exhibits growth laws that relate the macromolecular composition of the cell to the growth rate. Recent work has shown that these empirical regularities can be derived from coarse-grained models of resource allocation. While these studies focus on steady-state growth, such conditions are rarely found in natural habitats, where microorganisms are continually challenged by environmental fluctuations. The aim of this paper is to extend the study of microbial growth strategies to dynamical environments, using a self-replicator model. We formulate dynamical growth maximization as an optimal control problem that can be solved using Pontryagin’s Maximum Principle. We compare this theoretical gold standard with different possible implementations of growth control in bacterial cells. We find that simple control strategies enabling growth-rate maximization at steady state are suboptimal for transitions from one growth regime to another, for example when shifting bacterial cells to a medium supporting a higher growth rate. A near-optimal control strategy in dynamical conditions is shown to require information on several, rather than a single physiological variable. Interestingly, this strategy has structural analogies with the regulation of ribosomal protein synthesis by ppGpp in the enterobacterium Escherichia coli. It involves sensing a mismatch between precursor and ribosome concentrations, as well as the adjustment of ribosome synthesis in a switch-like manner. Our results show how the capability of regulatory systems to integrate information about several physiological variables is critical for optimizing growth in a changing environment. PMID:26958858

  7. Dynamical Allocation of Cellular Resources as an Optimal Control Problem: Novel Insights into Microbial Growth Strategies.

    Directory of Open Access Journals (Sweden)

    Nils Giordano

    2016-03-01

    Full Text Available Microbial physiology exhibits growth laws that relate the macromolecular composition of the cell to the growth rate. Recent work has shown that these empirical regularities can be derived from coarse-grained models of resource allocation. While these studies focus on steady-state growth, such conditions are rarely found in natural habitats, where microorganisms are continually challenged by environmental fluctuations. The aim of this paper is to extend the study of microbial growth strategies to dynamical environments, using a self-replicator model. We formulate dynamical growth maximization as an optimal control problem that can be solved using Pontryagin's Maximum Principle. We compare this theoretical gold standard with different possible implementations of growth control in bacterial cells. We find that simple control strategies enabling growth-rate maximization at steady state are suboptimal for transitions from one growth regime to another, for example when shifting bacterial cells to a medium supporting a higher growth rate. A near-optimal control strategy in dynamical conditions is shown to require information on several, rather than a single physiological variable. Interestingly, this strategy has structural analogies with the regulation of ribosomal protein synthesis by ppGpp in the enterobacterium Escherichia coli. It involves sensing a mismatch between precursor and ribosome concentrations, as well as the adjustment of ribosome synthesis in a switch-like manner. Our results show how the capability of regulatory systems to integrate information about several physiological variables is critical for optimizing growth in a changing environment.

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

    Directory of Open Access Journals (Sweden)

    Daniel McDonald

    2015-03-01

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

  9. Thyristor Controlled Reactor for Power Factor Improvement

    Directory of Open Access Journals (Sweden)

    Sheila Mahapatra

    2014-04-01

    Full Text Available Power factor improvement is the essence of any power sector for reliable operation. This paper provides Thyristor Controlled Reactor regulated by programmed microcontroller which aids in improving power factor and retaining it close to unity under various loading conditions. The implementation is done on 8051 microcontrollerwhich isprogrammed using Keil software. To determine time lag between current and voltage PSpice softwareis used and to display power factor according tothe variation in loadProteus software is used. Whenever a capacitive load is connected to the transmission linea shunt reactor is connected which injects lagging reactive VARs to the power system. As a result the power factor is improved. The results given in this paper provides suitable microcontroller based reactive power compensation and power factor improvement technique using a Thyristor Controlled Reactor module.

  10. Commercialization of the power factor controller

    Science.gov (United States)

    1981-01-01

    The purpose of the Motor Power Controller, also known as the Power Factor Controller, is to improve power factor and reduce power dissipation in induction motors operating below full load. These purposes were studied and tested in detail. The Motor Power Controller is capable of raising power factors from 0.2 to 0.8 and results in energy savings. It was found that many motors, in their present operating applications, are classified as unstable. The electronic nature of the controller vs. the electrical nature of the motor, compound this problem due to the differences in response time of the two devices. Many tests were successfully completed, the most indicating greater savings than anticipated. Also, there was an effect on efficiency which was not included in the calculations.

  11. Survival of microbial isolates from clouds toward simulated atmospheric stress factors

    Science.gov (United States)

    Joly, Muriel; Amato, Pierre; Sancelme, Martine; Vinatier, Virginie; Abrantes, Magali; Deguillaume, Laurent; Delort, Anne-Marie

    2015-09-01

    In the atmosphere, airborne microbial cells are exposed to conditions that are thought to affect their survival. Here, we investigated the survival of 5 microorganisms among the most represented in the cultivable community of clouds (4 bacteria affiliated to Pseudomonas, Sphingomonas and Arthrobacter and 1 yeast of Dioszegia) after exposition to different atmospheric factors generally considered stressful for cells: artificial solar light (10 h), oxidant (hydrogen peroxide: 0-1 mM for 90 min), osmotic shocks (0.1-2.5 M NaCl) and freeze-thaw cycles (6 cycles of 5 °C/-40 °C). Each condition was applied separately to cell suspensions, and survival rates were examined by culture. Survival was highly strain and stress dependent, with no relationship with pigmentation or ice nucleation activity. In all strains, solar light had no or mitigated influence, and exposition to H2O2 at the concentration measured in cloud water only slightly impacted viability (>70% of the cells survived). The strain Sphingomonas sp. was particularly impacted by osmotic shocks while repeated freeze-thaw was particularly damaging for Arthrobacter and Pseudomonas species. Overall, our results tend to indicate that in the atmosphere, the most stringent selection factors on living organisms are probably freeze-thaw and condensation/evaporation (osmotic shocks) cycles, whereas the impacts of oxidants and of solar light are limited.

  12. Microbial hydroxylation and glycosylation of pentacyclic triterpenes as inhibitors on tissue factor procoagulant activity.

    Science.gov (United States)

    Wang, Wei-Wei; Xu, Shao-Hua; Zhao, Ya-Zheng; Zhang, Chao; Zhang, Yuan-Yuan; Yu, Bo-Yang; Zhang, Jian

    2017-02-15

    To discover new inhibitors on tissue factor procoagulant activity, 20 pentacyclic triterpenes were semi-synthetized through microbial transformation and assayed on the model of human THP-1 cells stimulated by lipopolysaccharide. In the biotransformation two types of reactions were observed, regio-selective hydroxylation and glycosylation. The bioassay results showed that most of tested compounds were significant effective on this model and two of the biotransformation products 23-hydroxy-28-O-β-d-glucopyranosyl betulinic acid (3d) and 28-O-β-d-glucopyranosyl oleanic acid (1a) exhibited most potential activities with the IC50 values of 0.028, 0.035nM respectively. The preliminary structure and activity relationship analysis revealed that the aglycones with single free hydroxyl group on the skeleton (1, 1j) were less effective than that with more free hydroxyl groups (1d, 1f, 2), mono-glycosylation can significantly enhance their inhibitory effects. Our findings also provide some potential leading compounds for tissue factor-related diseases, such as cancer and cardiovascular diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Essential factors of an integrated moving bed biofilm reactor-membrane bioreactor: Adhesion characteristics and microbial community of the biofilm.

    Science.gov (United States)

    Tang, Bing; Yu, Chunfei; Bin, Liying; Zhao, Yiliang; Feng, Xianfeng; Huang, Shaosong; Fu, Fenglian; Ding, Jiewei; Chen, Cuiqun; Li, Ping; Chen, Qianyu

    2016-07-01

    This work aims at revealing the adhesion characteristics and microbial community of the biofilm in an integrated moving bed biofilm reactor-membrane bioreactor, and further evaluating their variations over time. With multiple methods, the adhesion characteristics and microbial community of the biofilm on the carriers were comprehensively illuminated, which showed their dynamic variation along with the operational time. Results indicated that: (1) the roughness of biofilm on the carriers increased very quickly to a maximum value at the start-up stage, then, decreased to become a flat curve, which indicated a layer of smooth biofilm formed on the surface; (2) the tightly-bound protein and polysaccharide was the most important factor influencing the stability of biofilm; (3) the development of biofilm could be divided into three stages, and Gammaproteobacteria were the most dominant microbial species in class level at the last stage, which occupied the largest ratio (51.48%) among all microbes.

  14. Review of Microbial Responses to Abiotic Environmental Factors in the Context of the Proposed Yucca Mountain Repository

    Energy Technology Data Exchange (ETDEWEB)

    Meike, A.; Stroes-Gascoyne, S.

    2000-08-01

    A workshop on Microbial Activities at Yucca Mountain (May 1995, Lafayette, CA) was held with the intention to compile information on all pertinent aspects of microbial activity for application to a potential repository at Yucca Mountain. The findings of this workshop set off a number of efforts intended to eventually incorporate the impacts of microbial behavior into performance assessment models. One effort was to expand an existing modeling approach to include the distinctive characteristics of a repository at Yucca Mountain (e.g., unsaturated conditions and a significant thermal load). At the same time, a number of experimental studies were initiated as well as a compilation of relevant literature to more thoroughly study the physical, chemical and biological parameters that would affect microbial activity under Yucca Mountain-like conditions. This literature search (completed in 1996) is the subject of the present document. The collected literature can be divided into four categories: (1) abiotic factors, (2) community dynamics and in-situ considerations, (3) nutrient considerations and (4) transport of radionuclides. The complete bibliography represents a considerable resource, but is too large to be discussed in one document. Therefore, the present report focuses on the first category, abiotic factors, and a discussion of these factors in order to facilitate the development of a model for Yucca Mountain.

  15. Mineral biotechnology. Microbial aspects of mineral beneficiation, metal extraction, and environmental control

    Energy Technology Data Exchange (ETDEWEB)

    Kawatra, S.K.; Natarajan, K.A. (eds.)

    2001-07-01

    Papers in this book illustrate the utility of mineral biotechnology with respect to biobeneficiation, bioleaching, bioremediation and biomineralization. Papers of particular interest to the coal industry include: depression of pyrite flotation by yeast and bacteris (S.K. Kawatra and T.C. Eisele); desulfurization of coal by microbial flotation in a semicontinuous system (T. Nagaoka and others); biochemical removal of HAP precursors from coal - INEEL slurry column testing (K.S. Noah and G.J. Olson); microorganisms, biotechnology and acid rock drainage - emphasis on passive-biological control and treatment methods (N. Kuyucak); and utility of bioreagents in mineral processing (P. Somasundaran and others).

  16. Microbial control of malaria: biological warfare against the parasite and its vector.

    Science.gov (United States)

    Abdul-Ghani, Rashad; Al-Mekhlafi, Abdulsalam M; Alabsi, Mogeeb S

    2012-02-01

    Microbial applications in malaria transmission control have drawn global attention. Mosquito midgut microbiota can modulate vector immunity and block Plasmodium development. Paratransgenic manipulation of bacterial symbionts and Wolbachia can affect reproductive characteristics of mosquitoes. Bacillus-based biolarvicides can control mosquito larvae in different breeding habitats, but their effectiveness differs according to the type of formulation applied, and the physical and ecological conditions of the environment. Entomopathogenic fungi show promise as effective and evolution-proof agents against adult mosquitoes. In addition, transgenic fungi can express anti-plasmodial effector molecules that can target the parasite inside its vector. Despite showing effectiveness in domestic environments as well as against insecticide-resistant mosquitoes, claims towards their deployability in the field and their possible use in integrated vector management programmes have yet to be investigated. Viral pathogens show efficacy in the interruption of sporogonic development of the parasite, and protozoal pathogens exert direct pathogenic potential on larvae and adults with substantial effects on mosquito longevity and fecundity. However, the technology required for their isolation and maintenance impedes their field application. Many agents show promising findings; however, the question remains about the epidemiologic reality of these approaches because even those that have been tried under field conditions still have certain limitations. This review addresses aspects of the microbial control of malaria between proof-of-concept and epidemiologic reality.

  17. Large-scale contamination of microbial isolate genomes by Illumina PhiX control.

    Science.gov (United States)

    Mukherjee, Supratim; Huntemann, Marcel; Ivanova, Natalia; Kyrpides, Nikos C; Pati, Amrita

    2015-01-01

    With the rapid growth and development of sequencing technologies, genomes have become the new go-to for exploring solutions to some of the world's biggest challenges such as searching for alternative energy sources and exploration of genomic dark matter. However, progress in sequencing has been accompanied by its share of errors that can occur during template or library preparation, sequencing, imaging or data analysis. In this study we screened over 18,000 publicly available microbial isolate genome sequences in the Integrated Microbial Genomes database and identified more than 1000 genomes that are contaminated with PhiX, a control frequently used during Illumina sequencing runs. Approximately 10% of these genomes have been published in literature and 129 contaminated genomes were sequenced under the Human Microbiome Project. Raw sequence reads are prone to contamination from various sources and are usually eliminated during downstream quality control steps. Detection of PhiX contaminated genomes indicates a lapse in either the application or effectiveness of proper quality control measures. The presence of PhiX contamination in several publicly available isolate genomes can result in additional errors when such data are used in comparative genomics analyses. Such contamination of public databases have far-reaching consequences in the form of erroneous data interpretation and analyses, and necessitates better measures to proofread raw sequences before releasing them to the broader scientific community.

  18. Is the mineralisation response to root exudation controlled by the microbial stoichiometric demand in subarctic soils?

    Science.gov (United States)

    Rousk, Johannes; Hicks, Lettice; Leizeaga, Ainara; Michelsen, Anders; Rousk, Kathrin

    2017-04-01

    Climate change will expose arctic and subarctic systems to warming and a shift towards plant communities with more rhizosphere labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed 'priming'. We investigated how warming (+1.1˚ C over ambient using open top chambers) and the addition of plant litter (90 g m-2 y-1) or organic nitrogen (N) (fungal fruit bodies; 90 g m-2 y-1) in the Subarctic influenced the susceptibility of SOM mineralisation to priming, and its microbial underpinnings. Root exudation were simulated with the addition of labile organic matter both in the form of only labile C (13C-glucose) or in the form of labile C and N (13C-alanine). We hypothesized that labile C would induce a higher mineralization of N than C sourced from SOM ("N mining"); a response unrelated to microbial growth responses. We also hypothesized that the N mining effect would be more pronounced in climate change simulation treatments of higher C/N (plant litter) than treatments with lower C/N (fungal fruitbodies and warming), with the control treatments intermediate. We also hypothesized that the addition of labile C and N would not result in selective N mining, but instead coupled responses of C and N mineralisation sourced from SOM; a response that would coincide with stimulated microbial growth responses. Labile C appeared to inhibit the mineralisation of C from SOM by up to 60% within hours. In contrast, the mineralisation of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile-C inhibited C mineralisation is compatible with previously reported findings termed 'preferential substrate utilisation' or 'negative apparent priming', while the stimulated N mineralisation responses echo recent reports of 'real priming' of SOM mineralisation. However, C and N mineralisation responses

  19. A microbial sensor for organophosphate hydrolysis exploiting an engineered specificity switch in a transcription factor

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Ramesh K.; Kern, Teresa L.; Kim, Youngchang; Tesar, Christine K.; Jedrzejczak, Robert; Joachimiak, Andrzej; Strauss, Charlie E E.

    2016-09-30

    A whole-cell biosensor utilizing a transcription factor (TF) is an effective tool for sensitive and selective detection of specialty chemicals or anthropogenic molecules, but requires access to an expanded repertoire of TFs. Using homology modeling and ligand docking for binding pocket identification, assisted by conservative mutations in the pocket, we engineered a novel specificity in an Acinetobacter TF, PobR, to ‘sense’ a chemical p-nitrophenol (pNP) and measured the response via a fluorescent protein reporter expressed from a PobR promoter. Out of 107 variants of PobR, four were active when dosed with pNP, with two mutants showing a specificity switch from the native effector 4-hydroxybenzoate (4HB). One of the mutants, pNPmut1 was then used to create a smart microbial cell responding to pNP production from hydrolysis of an insecticide, paraoxon, in a coupled assay involving phosphotriesterase (PTE) enzyme expressed from a separate promoter. We show the fluorescence of the cells correlated with the catalytic efficiency of the PTE variant expressed in each cell. High selectivity between similar molecules (4HB versus pNP), high sensitivity for pNP detection (~2 μM) and agreement of apo- and holo-structures of PobR scaffold with predetermined computational models are other significant results presented in this work.

  20. Enhancing factors of electricity generation in a microbial fuel cell using Geobacter sulfurreducens.

    Science.gov (United States)

    Kim, Mi-Sun; Cha, Jaehwan; Kim, Dong-Hoon

    2012-10-01

    In this study, we investigated various cultural and operational factors to enhance electricity generation in a microbial fuel cell (MFC) using Geobacter sulfurreducens. The pure culture of G. sulfurreducens was cultivated using various substrates including acetate, malate, succinate, and butyrate, with fumarate as an electron acceptor. Cell growth was observed only in acetate-fed medium, when the cell concentrations increased 4-fold for 3 days. A high acetate concentration suppressed electricity generation. As the acetate concentration was increased from 5 to 20 mM, the power density dropped from 16 to 13 mW/m2, whereas the coulombic efficiency (CE) declined by about half. The immobilization of G. sulfurreducens on the anode considerably reduced the enrichment period from 15 to 7 days. Using argon gas to create an anaerobic condition in the anode chamber led to increased pH, and electricity generation subsequently dropped. When the plain carbon paper cathode was replaced by Pt-coated carbon paper (0.5 mg Pt/cm2), the CE increased greatly from 39% to 83%.

  1. COMBINED MICROBIAL SURFACTANT-POLYMER SYSTEM FOR IMPROVED OIL MOBILITY AND CONFORMANCE CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Jorge Gabitto; Maria Barrufet

    2005-08-01

    Many domestic oil fields are facing abandonment even though they still contain two-thirds of their original oil. A significant number of these fields can yield additional oil using advanced oil recovery (AOR) technologies. To maintain domestic oil production at current levels, AOR technologies are needed that are affordable and can be implemented by the independent oil producers of the future. Microbial enhanced oil recovery (MEOR) technologies have become established as cost-effective solutions for declining oil production. MEOR technologies are affordable for independent producers operating stripper wells and can be used to extend the life of marginal fields. The demonstrated versatility of microorganisms can be used to design advanced microbial systems to treat multiple production problems in complex, heterogeneous reservoirs. The proposed research presents the concept of a combined microbial surfactant-polymer system for advanced oil recovery. The surfactant-polymer system utilizes bacteria that are capable of both biosurfactant production and metabolically-controlled biopolymer production. This novel technology combines complementary mechanisms to extend the life of marginal fields and is applicable to a large number of domestic reservoirs. The research project described in this report was performed by Bio-Engineering Inc., a woman owned small business, Texas A&M University and Prairie View A&M University, a Historically Black College and University. This report describes the results of our laboratory work to grow microbial cultures, the work done on recovery experiments on core rocks, and computer simulations. We have selected two bacterial strains capable of producing both surfactant and polymers. We have conducted laboratory experiments to determine under what conditions surfactants and polymers can be produced from one single strain. We have conduct recovery experiments to determine the performance of these strains under different conditions. Our results

  2. Soil organic matter content: a non-liner control on microbial respiration in soils

    Science.gov (United States)

    Schnecker, Jörg; Grandy, Stuart

    2016-04-01

    clover were similar to rye, different amounts of straw resulted in an almost linear relationship between OC content and respiratory loss. The low N content of straw may explain this, limiting microbial growth and the exploration for new resources. Microbes in the straw treatment likely remained in the "survival" phase. Our findings of a non-linear decrease of CO2 production with decreasing OC content indicate that spatial separation as an inherent property of SOM content is an important control on decomposition of soil organic matter. Knowledge of this controlling effect might be beneficial in many ways. For example, even small additions of plant residues to agricultural systems might strongly enhance N availability to microbes and plants. Further, the spatial distribution of new C inputs may regulate its potential to be decomposed or stabilized. Finally, our results will help to improve model parameterization and predictions about microbial limitations and potential changes in decomposition under a future climate.

  3. Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model

    Institute of Scientific and Technical Information of China (English)

    Fangyue LI; Joachim BEHRENDT; Knut WICHMANN; Ralf OTTERPOHL

    2009-01-01

    In this study, a mathematical model was established to predict the formation of the soluble microbial product (SMP) in a submerged membrane bioreaetor. The developed model was calibrated under the reference condition. Simulation results were in good agreement with the measured results under the reference condition. The calibrated model was then used in the scenario studies to evaluate the effect of three chosen operating parameters: hydraulic retention time (HRT),dissolved oxygen concentration, and sludge retention time (SRT). Simulation results revealed that the SMP dominated the soluble organic substances in the supernatant. The scenario studies also revealed that the HRT can be decreased to 1 h without deteriorating the effluent quality; dissolved oxygen concentration in the reactor can be kept at 2-3 mg/L to maintain the effluent quality, reduce the content of SMP, and minimize operating costs; the optimal SRT can be controlled to 10-15 d to achieve complete nitrification process, less membrane fouling potential, and acceptable organic removal efficiency.

  4. Direct evidence for microbial-derived soil organic matter formation and its ecophysiological controls

    Science.gov (United States)

    Kallenbach, Cynthia M.; Frey, Serita D.; Grandy, A. Stuart

    2016-11-01

    Soil organic matter (SOM) and the carbon and nutrients therein drive fundamental submicron- to global-scale biogeochemical processes and influence carbon-climate feedbacks. Consensus is emerging that microbial materials are an important constituent of stable SOM, and new conceptual and quantitative SOM models are rapidly incorporating this view. However, direct evidence demonstrating that microbial residues account for the chemistry, stability and abundance of SOM is still lacking. Further, emerging models emphasize the stabilization of microbial-derived SOM by abiotic mechanisms, while the effects of microbial physiology on microbial residue production remain unclear. Here we provide the first direct evidence that soil microbes produce chemically diverse, stable SOM. We show that SOM accumulation is driven by distinct microbial communities more so than clay mineralogy, where microbial-derived SOM accumulation is greatest in soils with higher fungal abundances and more efficient microbial biomass production.

  5. Humboldt's spa: microbial diversity is controlled by temperature in geothermal environments.

    Science.gov (United States)

    Sharp, Christine E; Brady, Allyson L; Sharp, Glen H; Grasby, Stephen E; Stott, Matthew B; Dunfield, Peter F

    2014-06-01

    Over 200 years ago Alexander von Humboldt (1808) observed that plant and animal diversity peaks at tropical latitudes and decreases toward the poles, a trend he attributed to more favorable temperatures in the tropics. Studies to date suggest that this temperature-diversity gradient is weak or nonexistent for Bacteria and Archaea. To test the impacts of temperature as well as pH on bacterial and archaeal diversity, we performed pyrotag sequencing of 16S rRNA genes retrieved from 165 soil, sediment and biomat samples of 36 geothermal areas in Canada and New Zealand, covering a temperature range of 7.5-99 °C and a pH range of 1.8-9.0. This represents the widest ranges of temperature and pH yet examined in a single microbial diversity study. Species richness and diversity indices were strongly correlated to temperature, with R(2) values up to 0.62 for neutral-alkaline springs. The distributions were unimodal, with peak diversity at 24 °C and decreasing diversity at higher and lower temperature extremes. There was also a significant pH effect on diversity; however, in contrast to previous studies of soil microbial diversity, pH explained less of the variability (13-20%) than temperature in the geothermal samples. No correlation was observed between diversity values and latitude from the equator, and we therefore infer a direct temperature effect in our data set. These results demonstrate that temperature exerts a strong control on microbial diversity when considered over most of the temperature range within which life is possible.

  6. Synergic system between photovoltaic module and microbial fuel cell with simultaneous pollution control

    Science.gov (United States)

    Vasyliv, Oresta; Dhere, Neelkanth G.

    2015-05-01

    Combined photovoltaic module-microbial fuel cell construction shows prospect of advanced autonomous functioning effective energy-production system with the possibility of round-the-clock power generation. Application of Desulfuromonas sp. as anode biocatalyst in photovoltaic (PV) - microbial fuel cell (MFC) could support highly effective eco-friendly energy derivation with simultaneous reduction of organic and inorganic wastes in water environment. D. acetoxidans is exoelectrogenic bacterium that supports S0-reduction with H2S formation and S0-oxidation while an electrode serves as the electron acceptor. Simultaneous sulfur redox processes enhance electron transfer to the electrode surface that may increase the effectiveness of microbial fuel cell performance. It was shown that D. acetoxidans IMV B-7384 possesses selective resistance to 0.5-2.5 mM of copper, iron, nickel, manganese and lead ions. Metal-resistant strains of this bacterium may help overcome H2S toxicity, which is produced because of dissimilative S0-reduction, since divalent cations will interact with sulfide ions, forming insoluble precipitates. Thus D. acetoxidans IMV B-7384 may be applied for remediation of toxic metal ions from water environments because of metal fixation in form of insoluble complexes of metal sulfides. D. acetoxidans IMV B-7384 is presumed to have the capability to convert organic compounds, such as malate, pyruvate, succinate and fumarate via reductive stage of tricarboxylic acid cycle. Thus application of effluents as anolyte in MFC, based on D. acetoxidans IMV B-7384, may cause decrease of its organic content with formation of simple benign constituents, such as CO2 and H2O. Hence the advanced system for eco-friendly energy generation with simultaneous water pollution control is proposed.

  7. Litter quality versus soil microbial community controls over decomposition: a quantitative analysis

    Science.gov (United States)

    Cleveland, Cory C.; Reed, Sasha C.; Keller, Adrienne B.; Nemergut, Diana R.; O'Neill, Sean P.; Ostertag, Rebecca; Vitousek, Peter M.

    2014-01-01

    The possible effects of soil microbial community structure on organic matter decomposition rates have been widely acknowledged, but are poorly understood. Understanding these relationships is complicated by the fact that microbial community structure and function are likely to both affect and be affected by organic matter quality and chemistry, thus it is difficult to draw mechanistic conclusions from field studies. We conducted a reciprocal soil inoculum × litter transplant laboratory incubation experiment using samples collected from a set of sites that have similar climate and plant species composition but vary significantly in bacterial community structure and litter quality. The results showed that litter quality explained the majority of variation in decomposition rates under controlled laboratory conditions: over the course of the 162-day incubation, litter quality explained nearly two-thirds (64 %) of variation in decomposition rates, and a smaller proportion (25 %) was explained by variation in the inoculum type. In addition, the relative importance of inoculum type on soil respiration increased over the course of the experiment, and was significantly higher in microcosms with lower litter quality relative to those with higher quality litter. We also used molecular phylogenetics to examine the relationships between bacterial community composition and soil respiration in samples through time. Pyrosequencing revealed that bacterial community composition explained 32 % of the variation in respiration rates. However, equal portions (i.e., 16 %) of the variation in bacterial community composition were explained by inoculum type and litter quality, reflecting the importance of both the meta-community and the environment in bacterial assembly. Taken together, these results indicate that the effects of changing microbial community composition on decomposition are likely to be smaller than the potential effects of climate change and/or litter quality changes in

  8. Stromatolite branching in the Neoproterozoic of the Centralian Superbasin, Australia: an investigation into sedimentary and microbial control of stromatolite morphology.

    Science.gov (United States)

    Planavsky, Noah; Grey, Kathleen

    2008-01-01

    The extensive and well-preserved Neoproterozoic Acaciella australica Stromatolite assemblage of Australia is ideal for examining the relative roles of microbial and environmental influences on stromatolite branching and stromatolite macrostructure across a wide geographical area. Detailed sedimentological analyses indicate that the basal hemispheroidal section of bioherms contains abundant sediment. By contrast, the columnar sections of bioherms are composed almost exclusively of micritic laminae. These micritic laminae display little evidence for environmental, especially sedimentary, control over stromatolite morphology. The change from a hemispheroidal morphology to branching morphology is linked to variations in the relative contributions of sediment and framework growth. The shift to columns appears to be closely linked to a decrease in sediment supply that resulted in a more stable environment in which microbially mediated framework growth began to control stromatolite morphology. Branching in the A. australica assemblage stromatolites appears to be caused by shifting sedimentary and microbial control on stromatolite morphology.

  9. Long-term tracking of microbial survivability and growth in a controlled environment

    Science.gov (United States)

    Sutandar, Andiyanto; Abdiel Foo, Jong Yong; Lim, Chu Sing; Hsu, Li-Yang

    2008-04-01

    The ecological and histological study of a microbial population in a given environment provides important information leading to its survivability and growth. Current standard laboratory practices adopt culture on a medium housed in an incubated environment. However, large numbers of cultures are usually required to investigate the effects of variations in parametric conditions on the microbes. This can result in a high use of resources such as consumables and man-hours. Automated systems that are able to replenish fresh nutrients and extract metabolic waste for long-term monitoring are also limited. In this study, a system capable of real-time monitoring of microbe survival and providing a suitable environment for their growth is presented. Housed within its structure is a customized chamber with temperature control, pH regulation, nutrient providence and metabolic waste removal functions. To assess the reliability of the system, five sets of Staphylococcus aureus ATCC 29213 strains are cultured and monitored continuously for 96 consecutive hours. The survival and growth of the pathogens are verified by standard laboratory techniques such as viable plate count after each successive 24 h of monitoring. The findings herein suggest that the system is able to monitor the microbial population with minimal human intervention and can be a valuable long-term tracking tool.

  10. An Overview on Novel Microbial Determination Methods in Pharmaceutical and Food Quality Control

    Directory of Open Access Journals (Sweden)

    Mahboob Nemati

    2016-09-01

    Full Text Available Traditional microbiological methods tend to be labor-intensive and time-consuming. Rapid and novel methods in microbiological tests provide more sensitive, precise and reproducible results compared with conventional methods. In microbiology, the most rapid testing methods belong to the field of biotechnology such as PCR, ELISA, ATP bioluminescence and etc. Nevertheless impedance microbiology, biosensors and analytical procedures to determine microbial constituents are of significance. The present review article was conducted using internet databases and related scientific literatures and articles that provide information on developments in the rapid methods in microbiology. The main focus is on the application of rapid methods in microbial quality control of pharmaceutical products. Reviewed literature showed that rapid methods and automation in microbiology is an advanced area for studying and applying of improved methods in the early detection, and characterization of microorganisms and their products in food, pharmaceutical and cosmetic industrials as well as environmental monitoring and clinical applications. It can be concluded that rapid methods and automation in microbiology should continue as potent and efficient technologies to develop the novel tests to be performed in the future because of the ever-increasing concerns about the safety of food and pharmaceutical products. However the main issues to be considered are the scale up of developed methods and the regulatory requirements.

  11. DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

    Energy Technology Data Exchange (ETDEWEB)

    Bill W. Bogan; Brigid M. Lamb; John J. Kilbane II

    2004-10-30

    The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Previous testing indicated that the growth, and the metal corrosion caused by pure cultures of sulfate reducing bacteria were inhibited by hexane extracts of some pepper plants. This quarter tests were performed to determine if chemical compounds other than pepper extracts could inhibit the growth of corrosion-associated microbes and to determine if pepper extracts and other compounds can inhibit corrosion when mature biofilms are present. Several chemical compounds were shown to be capable of inhibiting the growth of corrosion-associated microorganisms, and all of these compounds limited the amount of corrosion caused by mature biofilms to a similar extent. It is difficult to control corrosion caused by mature biofilms, but any compound that disrupts the metabolism of any of the major microbial groups present in corrosion-associated biofilms shows promise in limiting the amount/rate of corrosion.

  12. EVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

    Energy Technology Data Exchange (ETDEWEB)

    Bill W. Bogan; Wendy R. Sullivan; Kristine M. H. Cruz; Kristine L. Lowe; John J. Kilbane II

    2004-04-30

    The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Previous testing of pepper extracts resulted in preliminary data indicating that some pepper extracts inhibit the growth of some corrosion-associated microorganisms. This quarter additional tests were performed to more specifically investigate the ability of three pepper extracts to inhibit the growth, and to influence the metal corrosion caused by two microbial species: Desulfovibrio vulgaris, and Comomonas denitrificans. All three pepper extracts rapidly killed Desulfovibrio vulgaris, but did not appear to inhibit Comomonas denitrificans. While corrosion rates were at control levels in experiments with Desulfovibrio vulgaris that received pepper extract, corrosion rates were increased in the presence of Comomonas denitrificans plus pepper extract. Further testing with a wider range of pure bacterial cultures, and more importantly, with mixed bacterial cultures should be performed to determine the potential effectiveness of pepper extracts to inhibit MIC.

  13. Effect of fixed orthodontic appliances on salivary microbial parameters at 6 months: a controlled observational study

    Directory of Open Access Journals (Sweden)

    Delphine MARET

    2014-01-01

    Full Text Available Objective: The aim of this study was to assess the microbial changes in children with fixed orthodontic appliances compared with a control group of children without orthodontic treatment. Material and Methods: Ninety-five children, aged between 12 and 16 years, participated in this study. Forty-eight subjects were fitted with fixed orthodontic appliances and forty-seven were free of any such appliances. The follow-up was 6 months for all children. The association between orthodontic appliances and high levels of Streptococcus mutans and Lactobacillus spp was assessed with logistic regression models, taking age, sex, pH and buffer capacity into account. Results: Differences at baseline between the two groups were not statistically significant. We found that wearing a fixed orthodontic appliance was associated with high levels of Streptococcus mutans and Lactobacillus spp (adjusted OR: 6.65, 95% CI [1.98-22.37]; 9.49, 95% CI [2.57-35.07], respectively, independently of other variables. Conclusion: The originality of the present epidemiological study was to evaluate the evolution of salivary microbial parameters in a population of children with fixed orthodontic appliances. Our results show an increase of Streptococcus mutans and Lactobacillus spp values during the follow-up. The whole dental workforce should be aware that preventive measures are of paramount importance during orthodontic treatment.

  14. Zero-power autonomous buoyancy system controlled by microbial gas production

    Science.gov (United States)

    Wu, Peter K.; Fitzgerald, Lisa A.; Biffinger, Justin C.; Spargo, Barry J.; Houston, Brian H.; Bucaro, Joseph A.; Ringeisen, Bradley R.

    2011-05-01

    A zero-power ballast control system that could be used to float and submerge a device solely using a gas source was built and tested. This system could be used to convey sensors, data loggers, and communication devices necessary for water quality monitoring and other applications by periodically maneuvering up and down a water column. Operational parameters for the system such as duration of the submerged and buoyant states can be varied according to its design. The gas source can be of any origin, e.g., compressed air, underwater gas vent, gas produced by microbes, etc. The zero-power ballast system was initially tested using a gas pump and further tested using gas produced by Clostridium acetobutylicum. Using microbial gas production as the only source of gas and no electrical power during operation, the system successfully floated and submerged periodically with a period of 30 min for at least 24 h. Together with microbial fuel cells, this system opens up possibilities for underwater monitoring systems that could function indefinitely.

  15. An Overview on Novel Microbial Determination Methods in Pharmaceutical and Food Quality Control

    Science.gov (United States)

    Nemati, Mahboob; Hamidi, Aliasghar; Maleki Dizaj, Solmaz; Javaherzadeh, Vahid; Lotfipour, Farzaneh

    2016-01-01

    Traditional microbiological methods tend to be labor-intensive and time-consuming. Rapid and novel methods in microbiological tests provide more sensitive, precise and reproducible results compared with conventional methods. In microbiology, the most rapid testing methods belong to the field of biotechnology such as PCR, ELISA, ATP bioluminescence and etc. Nevertheless impedance microbiology, biosensors and analytical procedures to determine microbial constituents are of significance. The present review article was conducted using internet databases and related scientific literatures and articles that provide information on developments in the rapid methods in microbiology. The main focus is on the application of rapid methods in microbial quality control of pharmaceutical products. Reviewed literature showed that rapid methods and automation in microbiology is an advanced area for studying and applying of improved methods in the early detection, and characterization of microorganisms and their products in food, pharmaceutical and cosmetic industrials as well as environmental monitoring and clinical applications. It can be concluded that rapid methods and automation in microbiology should continue as potent and efficient technologies to develop the novel tests to be performed in the future because of the ever-increasing concerns about the safety of food and pharmaceutical products. However the main issues to be considered are the scale up of developed methods and the regulatory requirements. PMID:27766214

  16. Biostimulation of Iron Reduction and Uranium Immobilization: Microbial and Mineralogical Controls

    Energy Technology Data Exchange (ETDEWEB)

    Joel E. Kostka

    2008-02-06

    This project represented a joint effort between Florida State University (FSU), Rutgers University (RU), and the University of Illinois (U of I). FSU served as the lead institution and Dr. J.E. Kostka was responsible for project coordination, integration, and deliverables. This project was designed to elucidate the microbial ecology and geochemistry of metal reduction in subsurface environments at the U.S. DOE-NABIR Field Research Center at Oak Ridge, Tennessee (ORFRC). Our objectives were to: 1) characterize the dominant iron minerals and related geochemical parameters likely to limit U(VI) speciation, 2) directly quantify reaction rates and pathways of microbial respiration (terminal-electron-accepting) processes which control subsurface sediment chemistry, and 3) identify and enumerate the organisms mediating U(VI) transformation. A total of 31 publications and 47 seminars or meeting presentations were completed under this project. One M.S. thesis (by Nadia North) and a Ph.D. dissertation (by Lainie Petrie-Edwards) were completed at FSU during fall of 2003 and spring of 2005, respectively. Ph.D. students, Denise Akob and Thomas Gihring have continued the student involvement in this research since fall of 2004. All of the above FSU graduate students were heavily involved in the research, as evidenced by their regular attendance at PI meetings and ORFRC workshops.

  17. A hybrid microbial fuel cell stack based on single and double chamber microbial fuel cells for self-sustaining pH control

    Science.gov (United States)

    Yang, Wei; Li, Jun; Ye, Dingding; Zhang, Liang; Zhu, Xun; Liao, Qiang

    2016-02-01

    Proton accumulation in the anode chamber is the major problem that affects the operational stability and electricity generation performance of double chamber microbial fuel cells (MFCs). In this study, a hybrid microbial fuel cell stack (DS-DS stack) based on single (SCMFCs) and double chamber MFCs (DCMFCs) is proposed for self-sustaining pH control in the MFC stack. It is found that the aerobic microbial oxidation of acetate by the biofilm that is attached to the air cathode of SCMFCs is responsible for the self-sustaining removal of accumulated H+ in the effluent of DCMFCs. Compared with the stack that solely consists of SCMFCs (SS-SS stack) or DCMFCs (DD-DD stack), the hybrid stack exhibits the highest electricity output performance and the most effective conversion of acetate into electricity at high power levels. Furthermore, the hybrid stack demonstrates the operation time of 15.7 ± 1.1 h when the operating voltage is above 0.8 V. This value is much higher than that of the DD-DD (8.5 ± 2.4 h) and SS-SS (8.1 ± 1.4 h) stacks, which suggests that the hybrid stack had a good operational stability.

  18. A conserved peptide pattern from a widespread microbial virulence factor triggers pattern-induced immunity in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Hannah Böhm

    2014-11-01

    Full Text Available Microbe- or host damage-derived patterns mediate activation of pattern-triggered immunity (PTI in plants. Microbial virulence factor (effector-triggered immunity (ETI constitutes a second layer of plant protection against microbial attack. Various necrosis and ethylene-inducing peptide 1 (Nep1-like proteins (NLPs produced by bacterial, oomycete and fungal microbes are phytotoxic virulence factors that exert immunogenic activities through phytotoxin-induced host cell damage. We here show that multiple cytotoxic NLPs also carry a pattern of 20 amino acid residues (nlp20 that triggers immunity-associated plant defenses and immunity to microbial infection in Arabidopsis thaliana and related plant species with similar characteristics as the prototype pattern, bacterial flagellin. Characteristic differences in flagellin and nlp20 plant responses exist however, as nlp20s fail to trigger extracellular alkalinization in Arabidopsis cell suspensions and seedling growth inhibition. Immunogenic nlp20 peptide motifs are frequently found in bacterial, oomycete and fungal NLPs. Such an unusually broad taxonomic distribution within three phylogenetic kingdoms is unprecedented among microbe-derived triggers of immune responses in either metazoans or plants. Our findings suggest that cytotoxic NLPs carrying immunogenic nlp20 motifs trigger PTI in two ways as typical patterns and by inflicting host cell damage. We further propose that conserved structures within a microbial virulence factor might have driven the emergence of a plant pattern recognition system mediating PTI. As this is reminiscent of the evolution of immune receptors mediating ETI, our findings support the idea that there is a continuum between PTI and ETI.

  19. Plants control the seasonal dynamics of microbial N cycling in a beech forest soil by belowground C allocation.

    Science.gov (United States)

    Kaiser, Christina; Fuchslueger, Lucia; Koranda, Marianne; Gorfer, Markus; Stange, Claus F; Kitzler, Barbara; Rasche, Frank; Strauss, Joseph; Sessitsch, Angela; Zechmeister-Boltenstern, Sophie; Richter, Andreas

    2011-05-01

    Soil microbes in temperate forest ecosystems are able to cycle several hundreds of kilograms of N per hectare per year and are therefore of paramount importance for N retention. Belowground C allocation by trees is an important driver of seasonal microbial dynamics and may thus directly affect N transformation processes over the course of the year. Our study aimed at unraveling plant controls on soil N cycling in a temperate beech forest at a high temporal resolution over a time period of two years, by investigating the effects of tree girdling on microbial N turnover. In both years of the experiment, we discovered (1) a summer N mineralization phase (between July and August) and (2) a winter N immobilization phase (November-February). The summer mineralization phase was characterized by a high N mineralization activity, low microbial N uptake, and a subsequent high N availability in the soil. During the autumn/winter N immobilization phase, gross N mineralization rates were low, and microbial N uptake exceeded microbial N mineralization, which led to high levels of N in the microbial biomass and low N availability in the soil. The observed immobilization phase during the winter may play a crucial role for ecosystem functioning, since it could protect dissolved N that is produced by autumn litter degradation from being lost from the ecosystem during the phase when plants are mostly inactive. The difference between microbial biomass N levels in winter and spring equals 38 kg N/ha and may thus account for almost one-third of the annual plant N demand. Tree girdling strongly affected annual N cycling: the winter N immobilization phase disappeared in girdled plots (microbial N uptake and microbial biomass N were significantly reduced, while the amount of available N in the soil solution was enhanced). This was correlated to a reduced fungal abundance in autumn in girdled plots. By releasing recently fixed photosynthates to the soil, plants may thus actively control the

  20. On the selection of relevant environmental factors to predict microbial dynamics in solidified media.

    Science.gov (United States)

    Theys, T E; Geeraerd, A H; Devlieghere, F; Van Impe, J F

    2010-04-01

    Several studies have shown that food structure causes slower growth rates and narrower growth boundaries of bacteria compared to laboratory media. In predictive microbiology, both a(w) or corresponding solute concentration (mainly NaCl) have been used as a growth influencing factor for kinetic models or growth/no growth interface models. The majority of these models have been based on data generated in liquid broth media with NaCl as the predominant a(w) influencing solute. However, in complex food systems, other a(w) influencing components might be present, next to NaCl. In this study, the growth rate of Salmonella typhimurium was studied in the growth region and the growth/no growth response was tested in Tryptic Soy Broth at 20 degrees C at varying gelatin concentration (0, 10, 50 g L(-1) gelatin), pH (3.25-5.5) and water activity (a(w)) (0.929-0.996). From the viewpoint of water activity, the results suggest that NaCl is the main a(w) affecting compound. However, gelatin seemed to have an effect on medium a(w) too. Moreover, there is also an interaction effect between NaCl and gelatin. From the microbial viewpoint, the results confirmed that the a(w) decreasing effect of gelatin is less harmful to cells than the effect of Na(+) ions. The unexpected shift of the growth/no growth interface to more severe conditions when going from a liquid medium to a medium with 10 g L(-1) gelatin is more pronounced when formulating the models in terms of a(w) than in terms of NaCl concentrations. At 50 g L(-1) gelatin, the model factored with NaCl concentration shifts to milder conditions (concordant to literature results) while the model with a(w) indicates a further shift to more severe conditions, which is due to the water activity lowering effect of gelatin and the interaction between gelatin and NaCl. The results suggest that solute concentration should be used instead of a(w), both for kinetic models in the growth region and for growth/no growth interface models, if the

  1. DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

    Energy Technology Data Exchange (ETDEWEB)

    Bill W. Bogan; Brigid M. Lamb; Gemma Husmillo; Kristine Lowe; J. Robert Paterek; John J. Kilbane II

    2004-12-01

    The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Various chemicals that inhibit the growth and/or the metabolism of corrosion-associated microbes such as sulfate reducing bacteria, denitrifying bacteria, and methanogenic bacteria were evaluated to determine their ability to inhibit corrosion in experiments utilizing pure and mixed bacterial cultures, and planktonic cultures as well as mature biofilms. Planktonic cultures are easier to inhibit than mature biofilms but several compounds were shown to be effective in decreasing the amount of metal corrosion. Of the compounds tested hexane extracts of Capsicum pepper plants and molybdate were the most effective inhibitors of sulfate reducing bacteria, bismuth nitrate was the most effective inhibitor of nitrate reducing bacteria, and 4-((pyridine-2-yl)methylamino)benzoic acid (PMBA) was the most effective inhibitor of methanogenic bacteria. All of these compounds were demonstrated to minimize corrosion due to MIC, at least in some circumstances. The results obtained in this project are consistent with the hypothesis that any compound that disrupts the metabolism of any of the major microbial groups present in corrosion-associated biofilms shows promise in limiting the amount/rate of corrosion. This approach of controlling MIC by controlling the metabolism of biofilms is more environmentally benign than the current approach involving the use of potent biocides, and warrants further investigation.

  2. Improving Control of Microbially-Induced Mineral Precipitation in Flow Systems - Experiments and Modelling

    Science.gov (United States)

    Gerlach, R.; Phillips, A. J.; Lauchnor, E.; Ebigbo, A.; Connolly, J.; Mitchell, A. C.; Helmig, R.; Cunningham, A. B.; Spangler, L.

    2012-12-01

    Batch and flow experiments at atmospheric and geologic CO2 storage-relevant pressures in our laboratories have demonstrated the ability of microbial biofilms and biofilm produced calcium carbonate precipitates to decrease the permeability of natural and artificial porous media as well as improve the stability of unconsolidated porous media. Two overarching challenges in effectively implementing microbially induced calcium carbonate precipitation (MICP) are controlling (1) the spatial and temporal distribution of the formed precipitates and (2) the inactivation of microbes during the calcium carbonate precipitation process. Failure to control either one of those could result in injection well plugging or the necessity to implement costly cell-reinjection or -resuscitation strategies. Our recent work has focused on optimizing strategies for MICP in small (capillaries and micromodels), small columns (1 to 2.5 cm diameter, up to 5 cm in length), meso- (2 ft columns and 4 cm x 8 cm 2-d reactors) and large-scale (75 cm diameter, 38 cm high sandstone radial flow) systems. Results of these experiments have been modelled using two different approaches. (1) a microscale phase-field approach and (2) a large scale volume averaging approach. Close interaction between experimenters and modellers have resulted in improved injection strategies and the models are currently being used as experimental design tools. This presentation will focus on our recent efforts that combined 2 ft column experimentation with Darcy-scale modelling to calibrate and validate a model before utilizing the model for the optimization of biomineralization strategies in radial flow demonstrations in meso-scale sand stone cores at ambient and high pressures. Schematic pore-scale representation of MICP model

  3. 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.

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

    Science.gov (United States)

    Almatouq, Abdullah; Babatunde, Akintunde O

    2016-03-29

    This study investigated the mechanism and key factors influencing concurrent phosphorus (P) recovery and energy generation in microbial fuel cells (MFC) during wastewater treatment. Using a mediator-less dual chamber microbial fuel cell operated for 120 days; P was shown to precipitate as struvite when ammonium and magnesium chloride solutions were added to the cathode chamber. Monitoring data for chemical oxygen demand (COD), pH, oxidation reduction potential (ORP) and aeration flow rate showed that a maximum 38% P recovery was achieved; and this corresponds to 1.5 g/L, pH > 8, -550 ± 10 mV and 50 mL/min respectively, for COD, pH(cathode), ORP and cathode aeration flow rate. More importantly, COD and aeration flow rate were shown to be the key influencing factors for the P recovery and energy generation. Results further show that the maximum P recovery corresponds to 72 mW/m² power density. However, the energy generated at maximum P recovery was not the optimum; this shows that whilst P recovery and energy generation can be concurrently achieved in a microbial fuel cell, neither can be at the optimal value.

  5. Factors for Microbial Carbon Sources in Organic and Mineral Soils from Eastern United States Deciduous Forests

    Energy Technology Data Exchange (ETDEWEB)

    Stitt, Caroline R. [Mills College, Oakland, CA (United States)

    2013-09-16

    Forest soils represent a large portion of global terrestrial carbon; however, which soil carbon sources are used by soil microbes and respired as carbon dioxide (CO2) is not well known. This study will focus on characterizing microbial carbon sources from organic and mineral soils from four eastern United States deciduous forests using a unique radiocarbon (14C) tracer. Results from the dark incubation of organic and mineral soils are heavily influenced by site characteristics when incubated at optimal microbial activity temperature. Sites with considerable differences in temperature, texture, and location differ in carbon source attribution, indicating that site characteristics play a role in soil respiration.

  6. Biogeophysical interactions control the formation of iron oxide microbial biofilms in acidic geothermal outflow channels of Yellowstone National Park

    Science.gov (United States)

    Beam, J.; Berstein, H. C.; Jay, Z.; Kozubal, M. A.; Jennings, R. D.; Inskeep, W. P.

    2012-12-01

    during the initial stages of Fe (III)-oxide mat formation (water interface where oxygen microelectrode measurements reveal steep gradients in oxygen consumption (i.e., niche partitioning). A mature microbial mat is typically formed after ~2-4 months and reaches a pseudo-steady state depth of ~7-10 mm. Flow rates had a significant affect on Fe(III)-oxide deposition and community structure. These results suggest that dynamic biological, geochemical, and physical processes control the formation and cycling of Fe(III)-oxide microbial mats in acidic geothermal springs.

  7. Mineral Controls on Microbial Niche Space in Subsurface Serpentinites of the Coast Range Ophiolite, Northern California

    Science.gov (United States)

    Cardace, D.; Carnevale, D.; Schrenk, M. O.; Twing, K. I.; McCollom, T. M.; Hoehler, T. M.

    2012-12-01

    Serpentinites on Earth are excellent candidate environments for the origin of life and continue to serve as an outstanding model system for study of modern selection pressures (such as gradients in temperature, pressure, aqueous geochemistry, oxidation-reduction potential) on microbial communities. Recent coring (August 2011) in the Coast Range Ophiolite near Lower Lake, CA resulted in the establishment of two sets of reference continental serpentinite cores (to 30 and 42 m depth, respectively) and the installation of eight monitoring wells drawing from different depths. Six of these wells plumb serpentinizing waters, with characteristic high pH (up to 12.5), high calcium loads (10-200 ppm), and methane concentrations that are at or near one-atmosphere saturation, while hydrogen levels are orders of magnitude lower than is typically observed in other similar systems. Low hydrogen levels are cryptic; they may reflect consumption by microbial communities or possibly a pressure- or temperature-related solubility response. Two reference wells provide access to quasi-parallel, shallower groundwater flow regimes with near neutral pH values and surface-related major element and organic acid inventories. Many environmental parameters pertinent to microbiological communities active in serpentinites (such as dissolved hydrogen, methane, and other gas concentrations, redox status, ambient pH, and ionic strength) are largely controlled by host rock mineralogy and, thus, the temperature and progress of serpentinization. Since iron partitioning between co-existing minerals in serpentinites is strongly linked to the evolution of hydrogen (McCollom and Bach, 2009), we report here on mineralogy, bulk geochemistry, and selected mineral chemistry data for the serpentinite cores in order to constrain the production of hydrogen, the dominant bioenergetic driving force in this land-based deep biosphere setting. Parallel microbiological analyses of the same drill cores have shown the

  8. Controls on microbial accessibility to soil organic carbon following woody plant encroachment into grasslands

    Science.gov (United States)

    Creamer, Courtney; Boutton, Thomas; Olk, Dan; Filley, Timothy

    2010-05-01

    Woody plant encroachment (WPE) into savannas and grasslands is a global phenomenon that alters soil organic carbon (SOC) dynamics through changes in litter quality and quantity, soil structure, microbial ecology, and hydrology. To elucidate the controls on microbial accessibility to SOC, bulk soils from a chronosequence of progressive WPE into native grasslands at the Texas Agrilife La Copita Research Area were incubated for one year. The quantity and stable carbon isotope composition of respired CO2, and plant biopolymer chemistry in SOC were tracked. Respiration rates declined exponentially over the course of the experiment with 15-25% of the total CO2 respired released in the first month of incubation. Between 8 and 18% of the total SOC was mineralized to CO2 throughout the incubation. After day 84 a significantly (pproductivity. Despite documented SOC accrual following WPE at La Copita, we observed no evidence of enhanced SOC stabilization in these respiration experiments. In fact, a greater proportion of total SOC was lost from the soil of mature woody stands than from young stands, suggesting SOC accumulation observed with WPE may be due to greater input rates or microbial dynamics not captured in the laboratory incubation. Compound-specific analyses indicated there was a significant (pamino acids, and amino sugars during the incubation. Amino nitrogen tended to become more concentrated during the incubation, although the trend was not significant. Relatively few significant trends of these compounds in response to woody stand age were observed, indicating that these compounds were generally degraded to the same extent during the incubation. We hypothesize that biochemical recalcitrance is not an important mechanism for the stabilization of SOC at this site. By day 184 of the incubation, CO2 respired from older woody clusters (34-86 years) was significantly (p<0.05) less 13C-depleted with respect to bulk SOC than CO2 respired from younger woody clusters (14

  9. Effectiveness of microbial and chemical insecticides for supplemental control of bollworm on Bt and non-Bt cottons

    Science.gov (United States)

    Laboratory and field experiments were conducted to determine the effectiveness of microbial and chemical insecticides for supplemental control of bollworm (Helicoverpa zea Boddie) on non-Bt (DP1441®) and Bt (DP1321®) cottons. Neonate and 3rd instar larvae survival were evaluated on leaf tissue treat...

  10. Microbial antagonism as a potential solution for controlling selected root pathogens of crops

    Science.gov (United States)

    Cooper, Sarah; Agnew, Linda; Pereg, Lily

    2016-04-01

    Root pathogens of crops can cause large reduction in yield, however, there is a limited range of effective methods to control such pathogens. Soilborne pathogens that infect roots often need to survive in the rhizosphere, where there is high competition from other organisms. In such hot spots of microbial activity and growth, supported by root exudates, microbes have evolved antagonistic mechanisms that give them competitive advantages in winning the limited resources. Among these mechanisms is antibiosis, with production of some significant antifungal compounds including, antibiotics, volatile organic compounds, hydrogen cyanide and lytic enzymes. Some of these mechanisms may suppress disease through controlling the growth of root pathogens. In this project we isolated various fungi and bacteria that suppress the growth of cotton pathogens in vitro. The pathogen-suppressive microbes were isolated from cotton production soils that are under different management strategies, with and without the use of organic amendments. The potential of pathogen-suppressing microbes for controlling the black root rot disease, caused by the soilborne pathogen Thielaviopsis basicola, was confirmed using soil assays. We identified isolates with potential use as inoculant for cotton production in Australia. Having isolated a diverse group of antagonistic microbes enhances the probability that some would survive well in the soil and provide an alternative approach to address the problem of root disease affecting agricultural crops.

  11. The use of controlled microbial cenoses in producers' link to increase steady functioning of artificial ecosystems

    Science.gov (United States)

    Somova, Lydia; Mikheeva, Galina; Somova, Lydia

    The life support systems (LSS) for long-term missions are to use cycling-recycling systems, including biological recycling. Simple ecosystems include 3 links: producers (plants), consumers (man, animals) and reducers (microorganisms). Microorganisms are substantial component of every link of LSS. Higher plants are the traditional regenerator of air and producer of food. They should be used in many successive generations of their reproduction in LSS. Controlled microbiocenoses can increase productivity of producer's link and protect plants from infections. The goal of this work was development of methodological bases of formation of stable, controlled microbiocenoses, intended for increase of productivity of plants and for obtaining ecologically pure production of plants. Main results of our investigations: 1. Experimental microbiocenoses, has been produced in view of the developed methodology on the basis of natural association of microorganisms by long cultivation on specially developed medium. Dominating groups are bacteria of genera: Lactobacillus, Streptococcus, Leuconostoc, Bifidobacterium, Rhodopseudomonas and yeast of genera: Kluyveromyces, Saccharomyces, Torulopsis. 2. Optimal parameters of microbiocenosis cultivation (t, pH, light exposure, biogenic elements concentrations) were experimentally established. Conditions of cultivation on which domination of different groups of microbiocenosis have been found. 3. It was shown, that processing of seeds of wheat, oats, bulbs and plants Allium cepa L. (an onions) with microbial association raised energy of germination of seeds and bulbs and promoted the increase (on 20-30 %) of growth green biomass and root system of plants in comparison with the control. This work is supported by grant, Yenissey , 07-04-96806

  12. Control of Microbial Sulfide Production with Biocides and Nitrate in Oil Reservoir Simulating Bioreactors.

    Directory of Open Access Journals (Sweden)

    Yuan eXue

    2015-12-01

    Full Text Available Oil reservoir souring by the microbial reduction of sulfate to sulfide is unwanted, because it enhances corrosion of metal infrastructure used for oil production and processing. Reservoir souring can be prevented or remediated by the injection of nitrate or biocides, although injection of biocides into reservoirs is not commonly done. Whether combined application of these agents may give synergistic reservoir souring control is unknown. In order to address this we have used up-flow sand-packed bioreactors injected with 2 mM sulfate and volatile fatty acids (VFA, 3 mM each of acetate, propionate and butyrate at a flow rate of 3 or 6 pore volumes per day. Pulsed injection of the biocides glutaraldehyde (Glut, benzalkonium chloride (BAC and cocodiamine was used to control souring. Souring control was determined as the recovery time (RT needed to re-establish an aqueous sulfide concentration of 0.8-1 mM (of the 1.7-2 mM before the pulse. Pulses were either for a long time (120 h at low concentration (long-low or for a short time (1 h at high concentration (short-high. The short-high strategy gave better souring control with Glut, whereas the long-low strategy was better with cocodiamine. Continuous injection of 2 mM nitrate alone was not effective, because 3 mM VFA can fully reduce both 2 mM nitrate to nitrite and N2 and, subsequently, 2 mM sulfate to sulfide. No synergy was observed for short-high pulsed biocides and continuously injected nitrate. However, use of continuous nitrate and long-low pulsed biocide gave synergistic souring control with BAC and Glut, as indicated by increased RTs in the presence, as compared to the absence of nitrate. Increased production of nitrite, which increases the effectiveness of souring control by biocides, is the most likely cause for this synergy.

  13. Environmental controls on microbial abundance and activity on the greenland ice sheet: a multivariate analysis approach.

    Science.gov (United States)

    Stibal, Marek; Telling, Jon; Cook, Joe; Mak, Ka Man; Hodson, Andy; Anesio, Alexandre M

    2012-01-01

    Microbes in supraglacial ecosystems have been proposed to be significant contributors to regional and possibly global carbon cycling, and quantifying the biogeochemical cycling of carbon in glacial ecosystems is of great significance for global carbon flow estimations. Here we present data on microbial abundance and productivity, collected along a transect across the ablation zone of the Greenland ice sheet (GrIS) in summer 2010. We analyse the relationships between the physical, chemical and biological variables using multivariate statistical analysis. Concentrations of debris-bound nutrients increased with distance from the ice sheet margin, as did both cell numbers and activity rates before reaching a peak (photosynthesis) or a plateau (respiration, abundance) between 10 and 20 km from the margin. The results of productivity measurements suggest an overall net autotrophy on the GrIS and support the proposed role of ice sheet ecosystems in carbon cycling as regional sinks of CO(2) and places of production of organic matter that can be a potential source of nutrients for downstream ecosystems. Principal component analysis based on chemical and biological data revealed three clusters of sites, corresponding to three 'glacier ecological zones', confirmed by a redundancy analysis (RDA) using physical data as predictors. RDA using data from the largest 'bare ice zone' showed that glacier surface slope, a proxy for melt water flow, accounted for most of the variation in the data. Variation in the chemical data was fully explainable by the determined physical variables. Abundance of phototrophic microbes and their proportion in the community were identified as significant controls of the carbon cycling-related microbial processes.

  14. Application of the entomogenous fungus, Metarhizium anisopliae, for leafroller (Cnaphalocrocis medinalis) control and its effect on rice phyllosphere microbial diversity.

    Science.gov (United States)

    Hong, Mingsheng; Peng, Guoxiong; Keyhani, Nemat O; Xia, Yuxian

    2017-07-10

    Microbial pesticides form critical components of integrated pest management (IPM) practices. Little, however, is known regarding the impacts of these organisms on the indigenous microbial community. We show that Metarhizium anisopliae strain CQMa421 was highly effective in controlling the rice leafroller, Cnaphalocrocis medinalis Guenee. In addition, M. anisopliae distribution and its effects on phyllosphere microbial diversity after application in field trials were investigated. Phylloplane specific distribution of the fungus was observed over time, with more rapid declines of M. anisopliae CFUs (colony-forming units) seen in the top leaf layer as compared to lower layers. Application of the fungus resulted in transient changes in the endogenous microbial diversity with variations seen in the bacterial observed species and Shannon index. Notable increases in both parameters were seen at 6-day post-application of M. anisopliae, although significant variation within sample replicates for bacteria and fungi were noted. Application of M. anisopliae increased the relative distribution of bacterial species implicated in plant growth promotion and organic pollutant degradation, e.g., Methylobacterium, Sphingobium, and Deinococcus. These data show minimal impact of M. anisopliae on endogenous microbial diversity with transient changes in bacterial abundance/diversity that may result in added benefits to crops.

  15. Global microbial carbonate proliferation after the end-Devonian mass extinction: Mainly controlled by demise of skeletal bioconstructors

    Science.gov (United States)

    Yao, Le; Aretz, Markus; Chen, Jitao; Webb, Gregory E.; Wang, Xiangdong

    2016-12-01

    Microbial carbonates commonly flourished following mass extinction events. The end-Devonian (Hangenberg) mass extinction event is a first-order mass extinction on the scale of the ‘Big Five’ extinctions. However, to date, it is still unclear whether global microbial carbonate proliferation occurred after the Hangenberg event. The earliest known Carboniferous stromatolites on tidal flats are described from intertidal environments of the lowermost Tournaisian (Qianheishan Formation) in northwestern China. With other early Tournaisian microbe-dominated bioconstructions extensively distributed on shelves, the Qianheishan stromatolites support microbial carbonate proliferation after the Hangenberg extinction. Additional support comes from quantitative analysis of the abundance of microbe-dominated bioconstructions through the Famennian and early Tournaisian, which shows that they were globally distributed (between 40° latitude on both sides of the palaeoequator) and that their abundance increased distinctly in the early Tournaisian compared to the latest Devonian (Strunian). Comparison of variations in the relative abundance of skeleton- versus microbe-dominated bioconstructions across the Hangenberg and ‘Big Five’ extinctions suggests that changes in abundance of skeletal bioconstructors may play a first-order control on microbial carbonate proliferation during extinction transitions but that microbial proliferation is not a general necessary feature after mass extinctions.

  16. Safety factor profile control in a tokamak

    CERN Document Server

    Bribiesca Argomedo, Federico; Prieur, Christophe

    2014-01-01

    Control of the Safety Factor Profile in a Tokamak uses Lyapunov techniques to address a challenging problem for which even the simplest physically relevant models are represented by nonlinear, time-dependent, partial differential equations (PDEs). This is because of the  spatiotemporal dynamics of transport phenomena (magnetic flux, heat, densities, etc.) in the anisotropic plasma medium. Robustness considerations are ubiquitous in the analysis and control design since direct measurements on the magnetic flux are impossible (its estimation relies on virtual sensors) and large uncertainties remain in the coupling between the plasma particles and the radio-frequency waves (distributed inputs). The Brief begins with a presentation of the reference dynamical model and continues by developing a Lyapunov function for the discretized system (in a polytopic linear-parameter-varying formulation). The limitations of this finite-dimensional approach motivate new developments in the infinite-dimensional framework. The t...

  17. Evaluation of some microbial agents, natural and chemical compounds for controlling tomato leaf miner, Tuta absoluta (Meyrick (Lepidoptera: Gelechiidae

    Directory of Open Access Journals (Sweden)

    Abd El-Ghany Nesreen M.

    2016-12-01

    Full Text Available Solanaceous plants have a great economic impact in Egypt. These groups of plants include potatoes, tomatoes and eggplants. The new invasive pest of tomatoes, Tuta absoluta (Meyrick causes the greatest crop losses which can range from 60 to 100%. After its detection in Egypt during the last half of 2009, it spread quickly to all provinces in the country. We aiming to propose a sustainable control program for this devastating pest. In this research we tested three groups of control agents. The first was microbial and natural, the second - plant extracts and the third - chemical insecticides. Our results showed that the impact of T. absoluta can be greatly reduced by the use of sustainable control measures represented by different insecticide groups. Bioassay experiments showed that this devastating pest can be controlled with some compounds that give high mortality rates. Of these compounds, spinosad and Beauveria bassiana, microbial control agents, followed by azadirachtin, gave the best results in controlling T. absoluta. Of the chemical insecticides, lambda-cyhalotrin was the most effective, followed by lufenuron and profenofos. In conclusion we encourage farmers to use microbial and natural control measures in combating the tomato leafminer, T. absoluta, in Integrated Pest Mangement (IPM programs.

  18. Glyphosate toxicity and the effects of long-term vegetation control on soil microbial communities

    Science.gov (United States)

    Matt D. Busse; Alice W. Ratcliff; Carol J. Stestak; Robert F. Powers

    2001-01-01

    We assessed the direct and indirect effect of the herbicide glyphosate on soil microbial communities from soil bioassays at glyphosate concentrations up to 100-fold greater than expected following a single field application. Indirect effects on microbial biomass, respiration, and metabolic diversity (Biolog and catabolic response profile) were compared seasonally after...

  19. Key Factors Controlling the Applicability and Efficiency of Bioremediation of Chlorinated Ethenes In Situ

    Science.gov (United States)

    Zhang, M.; Yoshikawa, M.; Takeuchi, M.; Komai, T.

    2012-12-01

    Bioremediation has been considered as one of environmentally friendly and cost effective approaches for cleaning up the sites polluted by organic contaminants, such as chlorinated ethenes. Although bioremediation, in its widest sense, is not new, and many researches have been performed on bioremediation of different kinds of pollutants, an effective design and implication of in situ bioremediation still remains a challenging problem because of the complexity. Many factors may affect the applicability and efficiency of bioremediation of chlorinated ethenes in situ, which include the type and concentration of contaminants, biological, geological and hydro-geological conditions of the site, physical and chemical characteristics of groundwater and soils to be treated, as well as the constraints in engineering. In this presentation, an overview together with a detailed discussion on each factor will be provided. The influences of individual factors are discussed using the data obtained or cited from different sites and experiments, and thus under different environmental conditions. The results of this study illustrated that 1) the establishment of microbial consortium is of crucial importance for a complete degradation of chlorinated ethenes, 2) in situ control of favorable conditions for increasing microbial activities for bio-degradation through a designed pathway is the key to success, 3) the focus of a successful remediation system is to design an effective delivery process that is capable of producing adequate amendment mixing of contaminant-degrading bacteria, appropriate concentrations of electron acceptors, electron donors, and microbial nutrients in the subsurface treatment area.

  20. Impact of an Anticaries Mouthrinse on In Vitro Remineralization and Microbial Control

    Directory of Open Access Journals (Sweden)

    Frank C. Sun

    2014-01-01

    Full Text Available Objective. The objective of this research was to evaluate the caries control potential of a new fluoride mouthrinse that also contained antimicrobial agents and a biofilm disrupting agent using different in vitro models. Methods. Four in vitro studies were conducted to assess the performance of this three pronged approach to caries control: (1 traditional enamel fluoride uptake, (2 surface microhardness study using pH cycling model and subsequent fluoride uptake, (3 a salivary biofilm flow-through study to determine the anti-microbial activity, and (4 a single species biofilm model measuring effect on biofilm matrix disruption. Results. The data showed that a LISTERINE rinse with fluoride, essential oils and xylitol was superior in promoting enamel fluoride uptake and in enhancing antimicrobial activity over traditional commercially available fluoridated products. An increase of the surface microhardness was observed when the LISTERINE rinse was used in combination with fluoridated toothpaste versus the fluoridated toothpaste alone. Finally, it was demonstrated that xylitol solutions disrupted and reduced the biovolume of biofilm matrix of mature Streptococcus mutans. Conclusion. These in vitro studies demonstrated that a fluoride mouthrinse with antimicrobial agent and biofilm matrix disrupting agent provided multifaceted and enhanced anti-caries efficacy by promoting remineralization, reducing acidogenic bacteria and disrupting biofilm matrix.

  1. Controlling methanogenesis and improving power production of microbial fuel cell by lauric acid dosing.

    Science.gov (United States)

    Rajesh, P P; Noori, Md T; Ghangrekar, M M

    2014-01-01

    Methanogens compete with anodophiles for substrate and thus reduce the power generation and coulombic efficiency (CE) of the microbial fuel cell (MFC). Performance of a baked clayware membrane MFC inoculated with mixed anaerobic sludge pretreated with lauric acid was investigated in order to enhance power recovery by controlling methanogenesis. In the presence of lauric acid pretreated inoculum, MFC produced maximum volumetric power density of 4.8 W/m(3) and the CE increased from 3.6% (for untreated inoculum) to 11.6%. Cyclic voltammetry (CV) and electro-kinetic evaluation indicated a higher bio-catalytic activity at the anode of the MFC inoculated with lauric acid pretreated sludge. With the lauric acid pretreated inoculum a higher catalytic current of 114 mA, exchange current density of 40.78 mA/m(2) and lower charge transfer resistance of 0.00016 Ωm(2) were observed during oxidation at the anode. Addition of lauric acid significantly achieved suppression of methanogenesis and enhanced the sustainable power generation of MFC by 3.9 times as compared with control MFC inoculated with sludge without any pretreatment.

  2. Preliminary Evaluation of the Control of Microbial Fouling by Laboratory and Pilot-Scale Air-Stripping Columns

    Science.gov (United States)

    1985-03-01

    Corparisons, Journal AWWA, August 1981, p. 420. 11. American Public Health Association American Water Works Association Water Polution Control ...or control measures to be taken in future applications of these water treatment methods. Measures to prevent buildup of microbial slimes will allow...tap water --the town of Natick uses well water as the public water supply-- and flow was monitored with a "Gilmont model E6677" water flowmeter. The

  3. Comparing a microbial biocide and chlorine as zebra mussel control strategies in an Irish drinking water treatment plant

    OpenAIRE

    Sara Meehan; LUCY Frances E.; Bridget Gruber; Sarahann Rackl

    2013-01-01

    A need exists for an environmentally friendly mussel control method to replace chlorine and other traditional control methods currentlyutilised in drinking water plants and other infested facilities. Zequanox® is a newly commercialised microbial biocide for zebra and quaggamussels comprised of killed Pseudomonas fluorescens CL145A cells. The objective of this study was to compare the efficacy of adevelopmental formulation of Zequanox (referred to as MBI 401 FDP) and chlorine treatments on adu...

  4. Effect of some biotic factors on microbially-induced calcite precipitation in cement mortar

    Directory of Open Access Journals (Sweden)

    Yousef Al-Salloum

    2017-02-01

    Full Text Available Sporosarcina pasteurii, a common soil bacterium has been tested for microbial treatment of cement mortar. The present study also seeks to investigate the effects of growth medium, bacterial concentration and different buffers concerning the preparation of bacterial suspensions on the compressive strength of cement mortar. Two growth media, six different suspensions and two bacterial concentrations were used in the study. The influence of growth medium on calcification efficiency of S. pasteurii was insignificant. Significant improvement in the compressive as well as the tensile strength of cement mortar was observed. Microbial mineral precipitation visualized by Scanning Electron Microscopy (SEM shows fibrous material that increased the strength of cement mortar. Formation of thin strands of fillers observed through SEM micrographs improves the pore structure, impermeability and thus the compressive as well as the tensile strengths of the cement mortar. The type of substrate and its molarity have a significant influence on the strength of cement mortar.

  5. Childhood microbial keratitis

    Directory of Open Access Journals (Sweden)

    Abdullah G Al Otaibi

    2012-01-01

    Conclusion: Children with suspected microbial keratitis require comprehensive evaluation and management. Early recognition, identifying the predisposing factors and etiological microbial organisms, and instituting appropriate treatment measures have a crucial role in outcome. Ocular trauma was the leading cause of childhood microbial keratitis in our study.

  6. Factors affecting the microbial and chemical composition of silage. IV. Effect of wilting on maize silage.

    Science.gov (United States)

    Mahmoud, S A; Abdel-Hafez, A; Zaki, M M; Saleh, E A

    1979-01-01

    The effect of wilting on the microbial and chemical composition of ensiled maize plants was studied. Wilting stimulated high densities of lactic acid bacteria, with the decrease in counts of undesirable flora, i.e., yeasts, moulds, proteolytic and saccharolytic anaerobes, causing spoilage of silage. Moreover, wilting decreased the losses of dry matter, total acidity, and butyric acid content of silage. Accordingly, wilting proved to be a favourable treatment for the production of good quality silage from maize plants.

  7. Environmental dynamics as a structuring factor for microbial carbon utilization in a subtropical coastal lagoon.

    Science.gov (United States)

    Alonso, Cecilia; Piccini, Claudia; Unrein, Fernando; Bertoglio, Florencia; Conde, Daniel; Pernthaler, Jakob

    2013-01-01

    Laguna de Rocha belongs to a series of shallow coastal lagoons located along South America. It is periodically connected to the sea through a sand bar, exhibiting a hydrological cycle where physicochemical and biological gradients are rapidly established and destroyed. Its most frequent state is the separation of a Northern zone with low salinity, high turbidity and nutrient load, and extensive macrophyte growth, and a Southern zone with higher salinity and light penetration, and low nutrient content and macrophyte biomass. This zonation is reflected in microbial assemblages with contrasting abundance, activity, and community composition. The physicochemical conditions exerted a strong influence on community composition, and transplanted assemblages rapidly transformed to resembling the community of the recipient environment. Moreover, the major bacterial groups responded differently to their passage between the zones, being either stimulated or inhibited by the environmental changes, and exhibiting contrasting sensitivities to gradients. Addition of allochthonous carbon sources induced pronounced shifts in the bacterial communities, which in turn affected the microbial trophic web by stimulating heterotrophic flagellates and virus production. By contrast, addition of organic and inorganic nutrient sources (P or N) did not have significant effects. Altogether, our results suggest that (i) the planktonic microbial assemblage of this lagoon is predominantly carbon-limited, (ii) different bacterial groups cope differently with this constraint, and (iii) the hydrological cycle of the lagoon plays a key role for the alleviation or aggravation of bacterial carbon limitation. Based on these findings we propose a model of how hydrology affects the composition of bacterioplankton and of carbon processing in Laguna de Rocha. This might serve as a starting hypothesis for further studies about the microbial ecology of this lagoon, and of comparable transitional systems.

  8. Environmental dynamics as a structuring factor for microbial carbon utilization in a subtropical coastal lagoon

    Directory of Open Access Journals (Sweden)

    Cecilia eAlonso

    2013-02-01

    Full Text Available Laguna de Rocha belongs to a series of shallow coastal lagoons located along South America. It is periodically connected to the sea through a sand bar, exhibiting a hydrological cycle where physicochemical and biological gradients are rapidly established and destroyed. Its most frequent state is the separation of a Northern zone with low salinity, high turbidity and nutrient load, and extensive macrophyte growth, and a Southern zone with higher salinity and light penetration, and low nutrient content and macrophyte biomass. This zonation is reflected in microbial assemblages with contrasting abundance, activity and community composition. The physicochemical conditions exerted a strong influence on community composition, and transplanted assemblages rapidly transformed to resembling the community of the recipient environment. Moreover, the major bacterial groups responded differently to their passage between the zones, being either stimulated or inhibited by the environmental changes, and exhibiting contrasting sensitivities to gradients. Addition of allochthonous carbon sources induced pronounced shifts in the bacterial communities, which in turn affected the microbial trophic web by stimulating heterotrophic flagellates and virus production. By contrast, addition of organic and inorganic nutrient sources (P or N did not have significant effects. Altogether, our results suggest that i the planktonic microbial assemblage of this lagoon is predominantly carbon limited, ii different bacterial groups cope differently with this constraint, and iii the hydrological cycle of the lagoon plays a key role for the alleviation or aggravation of bacterial carbon limitation. Based on these findings we propose a model of how hydrology affects the composition of bacterioplankton and of carbon processing in Laguna de Rocha. This might serve as a starting hypothesis for further studies about the microbial ecology of this lagoon, and of comparable transitional

  9. Controlling the occurrence of power overshoot by adapting microbial fuel cells to high anode potentials

    KAUST Repository

    Zhu, Xiuping

    2013-04-01

    Power density curves for microbial fuel cells (MFCs) often show power overshoot, resulting in inaccurate estimation of MFC performance at high current densities. The reasons for power overshoot are not well understood, but biofilm acclimation and development are known factors. In order to better explore the reasons for power overshoot, exoelectrogenic biofilms were developed at four different anode potentials (-0.46 V, -0.24 V, 0 V, and 0.50 V vs. Ag/AgCl), and then the properties of the biofilms were examined using polarization tests and cyclic voltammetry (CV). The maximum power density of the MFCs was 1200±100 mW/m2. Power overshoot was observed in MFCs incubated at -0.46 V, but not those acclimated atmore positive potentials, indicating that bacterial activitywas significantly influenced by the anode acclimation potential. CV results further indicated that power overshoot of MFCs incubated at the lowest anode potential was associatedwith a decreasing electroactivity of the anodic biofilm in the high potential region,which resulted from a lack of sufficient electron transfer components to shuttle electrons at rates needed for these more positive potentials. © 2012 Elsevier B.V.

  10. Controlling the occurrence of power overshoot by adapting microbial fuel cells to high anode potentials.

    Science.gov (United States)

    Zhu, Xiuping; Tokash, Justin C; Hong, Yiying; Logan, Bruce E

    2013-04-01

    Power density curves for microbial fuel cells (MFCs) often show power overshoot, resulting in inaccurate estimation of MFC performance at high current densities. The reasons for power overshoot are not well understood, but biofilm acclimation and development are known factors. In order to better explore the reasons for power overshoot, exoelectrogenic biofilms were developed at four different anode potentials (-0.46 V, -0.24 V, 0 V, and 0.50 V vs. Ag/AgCl), and then the properties of the biofilms were examined using polarization tests and cyclic voltammetry (CV). The maximum power density of the MFCs was 1200±100 mW/m(2). Power overshoot was observed in MFCs incubated at -0.46 V, but not those acclimated at more positive potentials, indicating that bacterial activity was significantly influenced by the anode acclimation potential. CV results further indicated that power overshoot of MFCs incubated at the lowest anode potential was associated with a decreasing electroactivity of the anodic biofilm in the high potential region, which resulted from a lack of sufficient electron transfer components to shuttle electrons at rates needed for these more positive potentials.

  11. The importance of anabolism in microbial control over soil carbon storage

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chao; Schimel, Joshua P.; Jastrow, Julie D.

    2017-07-25

    Studies of the decomposition, transformation and stabilization of soil organic matter (SOM) have dramatically increased in recent years owing to growing interest in studying the global carbon (C) cycle as it pertains to climate change. While it is readily accepted that the magnitude of the organic C reservoir in soils depends upon microbial involvement, as soil C dynamics are ultimately the consequence of microbial growth and activity, it remains largely unknown how these microorganism-mediated processes lead to soil C stabilization. Here, we define two pathways—ex vivo modification and in vivo turnover—which jointly explain soil C dynamics driven by microbial catabolism and/or anabolism. Accordingly, we use the conceptual framework of the soil ‘microbial carbon pump’ (MCP) to demonstrate how microorganisms are an active player in soil C storage. The MCP couples microbial production of a set of organic compounds to their further stabilization, which we define as the entombing effect. This integration captures the cumulative long-term legacy of microbial assimilation on SOM formation, with mechanisms (whether via physical protection or a lack of activation energy due to chemical composition) that ultimately enable the entombment of microbial-derived C in soils. We propose a need for increased efforts and seek to inspire new studies that utilize the soil MCP as a conceptual guideline for improving mechanistic understandings of the contributions of soil C dynamics to the responses of the terrestrial C cycle under global change.

  12. Comparison of fluid geochemistry and microbiology of multiple organic-rich reservoirs in the Illinois Basin, USA: Evidence for controls on methanogenesis and microbial transport

    Science.gov (United States)

    Schlegel, Melissa E.; McIntosh, Jennifer C.; Bates, Brittney L.; Kirk, Matthew F.; Martini, Anna M.

    2011-04-01

    Microbial methane in sedimentary basins comprises approximately 20% of global natural gas resources, yet little is known about the environmental requirements and metabolic rates of these subsurface microbial communities. The Illinois Basin, located in the midcontinent of the United States, is an ideal location to investigate hydrogeochemical factors controlling methanogenesis as microbial methane accumulations occur: (1) in three organic-rich reservoirs of different geologic ages and organic matter types - Upper Devonian New Albany Shale (up to 900 m depth), Pennsylvanian coals (up to 600 m depth), and Quaternary glacial sediments (shallow aquifers); (2) across steep salinity gradients; and (3) with variable concentrations of SO42-. For all three organic-rich reservoirs aqueous geochemical conditions are favorable for microbial methanogenesis, with near neutral pH, SO42- concentrations methanogenic systems. Additionally, similar methanogenic communities are present in all three reservoirs with comparable cell counts (8.69E3-2.58E6 cells/mL). TRFLP results show low numbers of archaea species with only two dominant groups of base pairs in coals, shale, and limestone aquifers. These results compare favorably with other methanogen-containing deep subsurface environments. Individual hydrogeochemical parameters that have a Spearman correlation coefficient greater than 0.3 to variations in methanogenic species include stable isotopes of water (δ 18O and δD), type of substrate (i.e. coals versus shale), pH, and Cl - concentration. The matching of variations between methanogenic TRFLP data and conservative tracers suggests that deep circulation of meteoric waters influenced archaeal communities in the Illinois Basin. In addition, coalification and burial estimates suggest that in the study area, coals and shale reservoirs were previously sterilized (>80 °C in nutrient poor environments), necessitating the re-introduction of microbes into the subsurface via groundwater

  13. COMPOSITION AND METHOD FOR CONTROLLING MICROBIAL ADHESION AND BIOFILM FORMATION OF SURFACES

    DEFF Research Database (Denmark)

    2003-01-01

    in a large range of areas. The reduced numbers of adhered, attached or colonized microbial organisms is not due to a general growth inhibitory effect and therefore the anti-adhesive effect may not be caused by the presence of antimicrobials (antibiotics or non-antibiotics) in the fish extract.......The present invention describes how coating of surfaces with an extract, particularly a fish extract, can significantly reduce microbial adhesion, attachment, colonization and biofilm formation on surfaces. Such reduction of microbial adherence, attachment and colonization will be applicable...

  14. Utilization and control of ecological interactions in polymicrobial infections and community-based microbial cell factories [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Vinoth Wigneswaran

    2016-03-01

    Full Text Available Microbial activities are most often shaped by interactions between co-existing microbes within mixed-species communities. Dissection of the molecular mechanisms of species interactions within communities is a central issue in microbial ecology, and our ability to engineer and control microbial communities depends, to a large extent, on our knowledge of these interactions. This review highlights the recent advances regarding molecular characterization of microbe-microbe interactions that modulate community structure, activity, and stability, and aims to illustrate how these findings have helped us reach an engineering-level understanding of microbial communities in relation to both human health and industrial biotechnology.

  15. Factors controlling contrail cirrus optical depth

    Directory of Open Access Journals (Sweden)

    B. Kärcher

    2009-08-01

    Full Text Available Aircraft contrails develop into contrail cirrus by depositional growth and sedimentation of ice particles and horizontal spreading due to wind shear. Factors controlling this development include temperature, ice supersaturation, thickness of ice-supersaturated layers, and vertical gradients in the horizontal wind field. An analytical microphysical cloud model is presented and validated that captures these processes. Many individual contrail cirrus are simulated that develop differently owing to the variability in the controlling factors, resulting in large samples of cloud properties that are statistically analyzed. Contrail cirrus development is studied over the first four hours past formation, similar to the ages of line-shaped contrails that were tracked in satellite imagery on regional scales. On these time scales, contrail cirrus optical depth and microphysical variables exhibit a marked variability, expressed in terms of broad and skewed probability distribution functions. Simulated mean optical depths at a wavelength of 0.55 μm range from 0.05-0.5 and a substantial fraction 20-50% of contrail cirrus stay subvisible (optical depth <0.02, depending on meteorological conditions.

    A detailed analysis based on an observational case study over the continental USA suggests that previous satellite measurements of line-shaped persistent contrails have missed about 89%, 50%, and 11% of contrails with optical depths 0-0.05, 0.05-0.1, and 0.1-0.2, respectively, amounting to 65% of contrail coverage of all optical depths. When comparing observations with simulations and when estimating the contrail cirrus climate impact, not only mean values but also the variability in optical depth and microphysical properties need to be considered.

  16. Microbial mat controls on infaunal abundance and diversity in modern marine microbialites.

    Science.gov (United States)

    Tarhan, L G; Planavsky, N J; Laumer, C E; Stolz, J F; Reid, R P

    2013-09-01

    Microbialites are the most abundant macrofossils of the Precambrian. Decline in microbialite abundance and diversity during the terminal Proterozoic and early Phanerozoic has historically been attributed to the concurrent radiation of complex metazoans. Similarly, the apparent resurgence of microbialites in the wake of Paleozoic and Mesozoic mass extinctions is frequently linked to drastic declines in metazoan diversity and abundance. However, it has become increasing clear that microbialites are relatively common in certain modern shallow, normal marine carbonate environments-foremost the Bahamas. For the first time, we present data, collected from the Exuma Cays, the Bahamas, systematically characterizing the relationship between framework-building cyanobacteria, microbialite fabrics, and microbialite-associated metazoan abundance and diversity. We document the coexistence of diverse microbialite and infaunal metazoan communities and demonstrate that the predominant control upon both microbialite fabric and metazoan community structure is microbial mat type. These findings necessitate that we rethink prevalent interpretations of microbialite-metazoan interactions and imply that microbialites are not passive recipients of metazoan-mediated alteration. Additionally, this work provides support for the theory that certain Precambrian microbialites may have been havens of early complex metazoan life, rather than bereft of metazoans, as has been traditionally envisaged. © 2013 John Wiley & Sons Ltd.

  17. Maximising electricity production by controlling the biofilm specific growth rate in microbial fuel cells.

    Science.gov (United States)

    Ledezma, Pablo; Greenman, John; Ieropoulos, Ioannis

    2012-08-01

    The aim of this work is to study the relationship between growth rate and electricity production in perfusion-electrode microbial fuel cells (MFCs), across a wide range of flow rates by co-measurement of electrical output and changes in population numbers by viable counts and optical density. The experiments hereby presented demonstrate, for the first time to the authors' knowledge, that the anodic biofilm specific growth rate can be determined and controlled in common with other loose matrix perfusion systems. Feeding with nutrient-limiting conditions at a critical flow rate (50.8 mL h(-1)) resulted in the first experimental determination of maximum specific growth rate μ(max) (19.8 day(-1)) for Shewanella spp. MFC biofilms, which is considerably higher than those predicted or assumed via mathematical modelling. It is also shown that, under carbon-energy limiting conditions there is a strong direct relationship between growth rate and electrical power output, with μ(max) coinciding with maximum electrical power production.

  18. Microbial communities of the Costa Rica Margin: contamination controls and community analysis

    Science.gov (United States)

    Martino, A. J.; Biddle, J.; House, C. H.

    2013-12-01

    Most microbiology work in marine subsurface sediments has been focused in the upper 100-200 meters of sediment, as the switchover from advanced piston coring (APC) to extended core barrel coring (XCB) generally occurs around this depth. This leads to large increases in drilling-induced contamination and interferes in molecular studies. Here, we utilized deep 16S rRNA sequencing of DNA from both the subsurface sediments and the drilling fluid as a strategy for separating sequence information originating from drill-fluid contamination from that which represents the indigenous microbial communities of the sediments. This permitted a characterization of both sediment microbial communities and drilling-fluid communities that was thorough enough to confidently show the differences in the communities. Examination of the results suggests that sequences originating from drilling fluid may be only a minor portion of the data obtained from even the deepest XCB cores examined, and further that the different community composition of the drilling fluid should permit the subtraction of contaminating lineages from the analysis. As part of this work, we also show an extensive community composition analysis of multiple samples from two drilling sites of IODP Expedition 334, on the upper plate of the subduction zone between the Cocos plate and the Caribbean plate, off the Costa Rica Margin. Preliminary analysis of the sequence data suggests that the bacterial communities at both the upper slope site (1379) and the mid-slope site (1378) are dominated by Chloroflexi, Nitrospirae, Actinobacteria, Planctomycetes, and Proteobacteria, while Archaeal communities are dominated by the Miscellaneous Crenarchaeotal Group. Using universal primers revealed that the relative dominance of Bacteria to Archaea differs between the two sites, and the trends of increasing and decreasing abundance with depth are nearly opposite between the sites. At site 1379, the Bacterial to Archaeal relationship seems

  19. Anti-microbial peptide gene expression during oral vaccination: analysis of a randomized controlled trial.

    Science.gov (United States)

    Simuyandi, M; Kapulu, M; Kelly, P

    2016-11-01

    We have observed previously that micronutrient supplementation ameliorated suppression of α-defensin expression during diarrhoea. However, how interactions between anti-microbial peptide (AMP) expression and diarrhoeal disease are altered by micronutrient supplementation remain unclear. Using oral vaccination as a model of intestinal infection, we measured changes in AMP expression during multiple micronutrient supplementation. In the first part, volunteers underwent duodenal jejunal biopsy before and at 1, 2, 4 or 7 days after administration of one of three live, attenuated oral vaccines against rotavirus, typhoid and enterotoxigenic Escherichia coli. In the second part, participants were randomized to receive a multiple micronutrient supplement or placebo for 6 weeks before undergoing intestinal biopsy, vaccination against typhoid and rebiopsy after 14 days. Expression of human alpha-defensin (HD)5, HD6, hBD1, hBD2 and LL-37 was measured by quantitative reverse transcription-polymerase chain reaction. Taken together, the bacterial vaccines, but not rotavirus vaccine, reduced HD5 expression (P = 0·02, signed-rank test) and reduced LL-37 expression in seven of the eight individuals whose biopsies had expression prevaccination (P = 0·03). hBD2 was not detected. In the controlled trial, HD5 and HD6 expression after vaccination was lower [median ratio 0·5, interquartile range (IQR) = 0·07-2·2 and 0·58, IQR = 0·13-2·3, respectively] than before vaccination. There was no significant effect detected of micronutrient supplementation on expression of HD5, HD6, hBD1 or LL-37. We conclude that live attenuated bacterial vaccines, but not rotavirus vaccine, can reduce intestinal α-defensins, and typhoid vaccine reduced LL-37 expression. We found no evidence that micronutrient supplementation in the short term had any impact on anti-microbial peptide expression. © 2016 The Authors. Clinical & Experimental Immunology published by John Wiley & Sons Ltd

  20. Plant and microbial controls on nitrogen retention and loss in a Humid Tropical Forest

    Energy Technology Data Exchange (ETDEWEB)

    Templer, P.; Silver, W.; Pett-Ridge, J.; DeAngelis, K.M.; Firestone, M.K.

    2009-09-15

    Humid tropical forests are generally characterized by the lack of nitrogen (N) limitation to net primary productivity, yet paradoxically have high potential for N loss. We conducted an intensive field experiment with {sup 15}NH{sub 4} and {sup 15}NO{sub 3} additions to highly weathered tropical forest soils to determine the relative importance of N retention and loss mechanisms. Over half of all the NH{sub 4}{sup +} produced from gross mineralization was rapidly converted to NO{sub 3}{sup -} during the process of gross nitrification. During the first 24 h plant roots took up 28 % of the N mineralized, dominantly as NH{sub 4}{sup +}, and were a greater sink for N than soil microbial biomass. Soil microbes were not a significant sink for added {sup 15}NH{sub 4}{sup +} or {sup 15}NO{sub 3}{sup -} during the first 24 hr, and only for {sup 15}NH{sub 4}{sup +} after 7 d. Patterns of microbial community composition, as determined by Terminal Restriction Fragment Length Polymorphism analysis, were weakly, but significantly correlated with nitrification and denitrification to N{sub 2}O. Rates of dissimilatory NO{sub 3}{sup -} reduction to NH{sub 4}{sup +} (DNRA) were high in this forest, accounting for up to 25 % of gross mineralization and 35 % of gross nitrification. DNRA was a major sink for NO{sub 3}{sup -} which may have contributed to the lower rates of N{sub 2}O and leaching losses. Despite considerable N conservation via DNRA and plant NH{sub 4}{sup +} uptake, the fate of approximately 45% of the NO{sub 3}{sup -} produced and 22% of the NH{sub 4}{sup +} produced were not measured in our fluxes, suggesting that other important pathways for N retention and loss (e.g., denitrification to N{sub 2}) are important in this system. The high proportion of mineralized N that was rapidly nitrified and the fates of that NO{sub 3}{sup -} highlight the key role of gross nitrification as a proximate control on N retention and loss in humid tropical forest soils. Furthermore, our

  1. Microbial Characteristics of Peri-Implantitis : A Case-Control Study

    NARCIS (Netherlands)

    de Waal, Y C M; Eijsbouts, H V L C; Winkel, E G; van Winkelhoff, A J

    2016-01-01

    BACKGROUND: Aim of this case-control study was to compare oral microbiological characteristics of subjects with healthy peri-implant conditions and subjects with peri-implantitis and to explore the influence of various patient-related and implant-related factors on the microbiological characteristic

  2. Microbial Characteristics of Peri-Implantitis : A Case-Control Study

    NARCIS (Netherlands)

    de Waal, Y C M; Eijsbouts, H V L C; Winkel, E G; van Winkelhoff, A J

    BACKGROUND: Aim of this case-control study was to compare oral microbiological characteristics of subjects with healthy peri-implant conditions and subjects with peri-implantitis and to explore the influence of various patient-related and implant-related factors on the microbiological

  3. Microbial Pest Control Agents: Are they a Specific And Safe Tool for Insect Pest Management?

    Science.gov (United States)

    Deshayes, Caroline; Siegwart, Myriam; Pauron, David; Froger, Josy-Anne; Lapied, Bruno; Apaire-Marchais, Véronique

    2017-01-01

    Microorganisms (viruses, bacteria and fungi) or their bioactive agents can be used as active substances and therefore are referred as Microbial Pest Control Agents (MPCA). They are used as alternative strategies to chemical insecticides to counteract the development of resistances and to reduce adverse effects on both environment and human health. These natural entomopathogenic agents, which have specific modes of action, are generally considered safer as compared to conventional chemical insecticides. Baculoviruses are the only viruses being used as the safest biological control agents. They infect insects and have narrow host ranges. Bacillus thuringiensis (Bt) is the most widely and successfully used bioinsecticide in the integrated pest management programs in the world. Bt mainly produces crystal delta-endotoxins and secreted toxins. However, the Bt toxins are not stable for a very long time and are highly sensitive to solar UV. So genetically modified plants that express toxins have been developed and represent a large part of the phytosanitary biological products. Finally, entomopathogenic fungi and particularly, Beauveria bassiana and Metarhizium anisopliae, are also used for their insecticidal properties. Most studies on various aspects of the safety of MPCA to human, non-target organisms and environment have only reported acute but not chronic toxicity. This paper reviews the modes of action of MPCA, their toxicological risks to human health and ecotoxicological profiles together with their environmental persistence. This review is part of the special issue "Insecticide Mode of Action: From Insect to Mammalian Toxicity". Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  4. 鲜切果蔬微生物污染及控制研究进展%Research progress in control and microbial infection of fresh-cut fruits and vegetables

    Institute of Scientific and Technical Information of China (English)

    吴晓彬; 胡文忠; 刘程惠; 韩巍巍

    2011-01-01

    Microbial infection is one of the most important factors influencing quality of fresh-cut fruits and vegetables. In this paper,the sources and species of microbial,which effect on physiology of fresh-cut fruits and vegetables,were reviewed. The control methods on microbial of fresh-cut fruits and vegetables were introduced at home and abroad.%微生物侵染是影响鲜切果蔬品质的重要因素之一.本文概述了鲜切果蔬中微生物的污染来源、种类及其对鲜切果蔬组织生理的影响,并对国内外微生物的控制方法进行了介绍.

  5. Importance of microbial pest control agents and their metabolites In relation to the natural microbiota on strawberry

    DEFF Research Database (Denmark)

    Jensen, Birgit; Knudsen, Inge M. B.; Jensen, Dan Funck

    control. A series of laboratory, growth chamber, semi-field and field experiments using strawberry as a model plant focusing on commercial microbial pest control products (MPCPs) or laboratory MPCAs expected to be on the market within 10 years served as our experimental platform. Initially the background......, fungicide sensitivity and performance (establishment, growth and survival). Among the MPCAs tested only the laboratory MPCAs C. rosea and U. atrum demonstrated biocontrol effects against the strawberry pathogen Botrytis cinerea and the background microbial community was unaffected by both C. rosea and U...... in conventional strawberry production had no fungicidal effects on any of the MPCAs. Establishment of Trichoderma (TRI003) on berries following flower application was poor and applying fungicides prior to the MPCA application did not result in improved MPCA performance. In conclusion, the relative importance...

  6. Experimental factors affecting PCR-based estimates of microbial species richness and evenness

    Energy Technology Data Exchange (ETDEWEB)

    Engelbrektson, Anna; Kunin, Victor; Wrighton, Kelly C.; Zvenigorodsky, Natasha; Chen, Feng; Ochman, Howard; Hugenholtz, Philip

    2009-12-01

    Pyrosequencing of 16S rRNA gene amplicons for microbial community profiling can, for equivalent costs, yield greater than two orders of magnitude more sensitivity than traditional PCR-cloning and Sanger sequencing. With this increased sensitivity and the ability to analyze multiple samples in parallel, it has become possible to evaluate several technical aspects of PCRbased community structure profiling methods. We tested the effect of amplicon length and primer pair on estimates of species richness number of species and evenness relative abundance of species by assessing the potentially tractable microbial community residing in the termite hindgut. Two regions of the 16S rRNA gene were sequenced from one of two common priming sites, spanning the V1-V2 or V8 regions, using amplicons ranging n length from 352 to 1443 bp. Our results demonstrate that both amplicon length and primer pair markedly influence estimates of richness and evenness. However, estimates of species evenness are consistent among different primer pairs targeting the same region. These results highlight the importance of experimental methodology when comparing diversity estimates across communities.

  7. Biological effects of native and exotic plant residues on plant growth, microbial biomass and N availability under controlled conditions

    OpenAIRE

    Diallo, Mariama-Dalanda; Duponnois, Robin; Guisse, A.; Sall, Saïdou; Chotte, Jean-Luc; Thioulouse, J.

    2006-01-01

    The leaf litter of six tropical tree species (Acacia holosericea, Acacia tortilis, Azadirachta indica, Casuarina equisetifolia, Cordyla pinnata and Faidherbia albida) frequently used in agroforestry plantations in Sahelian and Soudano-Sahelian areas were tested for their influence on soil nitrogen content, microbial biomass and plant growth under controlled greenhouse conditions. Half of the soil was planted with onion (Allium cepa L.) seedlings and the other half was not. Two herbaceous spec...

  8. Lessons from interactions within the cassava green mite fungal pathogen Neozygites tanajoae system and prospects for microbial control using Entomophthorales.

    Science.gov (United States)

    Hountondji, Fabien C C

    2008-12-01

    Most fungal pathogens lack the capacity to search for their host but rather develop sit-and-wait strategies that favour contact with them. The success of these strategies depends upon the interactions of the pathogen with its host, the host plant and the environmental conditions, which altogether determine its transmissibility. Given the limited success that has characterized application of sustainable microbial control, particularly using Entomophthorales, interaction studies have been conducted with the entomophthoralean fungus Neozygites tanajoae, pathogenic to the cassava green mite (CGM), Mononychellus tanajoa, to help understand differences observed between laboratory and field performances of this pathogen. Reciprocal pathogen-host interactions as well as tritrophic interactions involving the host plant were studied. It was found that herbivory triggers the release of volatiles that promote sporulation of isolates of N. tanajoae, whereas the host mite avoids haloes of spores of this pathogen. However, the host mite does not avoid the pathogen when inside the mummified fungus-killed cadaver. The status of microbial control of CGM in Africa is reviewed and implications of these interactions are discussed for prospective application of microbial control using Entomophthorales.

  9. Control factors of partial nitritation for landfill leachate treatment

    Institute of Scientific and Technical Information of China (English)

    LIANG Zhu; LIU Jun-xin

    2007-01-01

    Anaerobic ammonium oxidation (ANAMMOX) technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen (NH4+-N) and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen (DO) concentration and the ammonium volumetric loading rate (Nv) had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4+-N/(m3·d), and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows: more than 94% partial nitritation efficiency (nitrite as the main product), 60%-74% NH4+-N removal efficiency, and NO2--N/NH4+-N ratio (concentration ratio) of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria (AOB) could be acclimated to higher FA (free ammonium) in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria (NOB) and other microorganisms in the reactor.

  10. Colon cancer controls versus population controls in case-control studies of occupational risk factors

    Directory of Open Access Journals (Sweden)

    Sabroe Svend

    2004-04-01

    Full Text Available Abstract Background Since updated population registers do not exist in many countries it is often difficult to sample valid population controls from the study base to a case-control study. Use of patient controls is an alternative option if the exposure experience under study for these patients are interchangeable with the experience for population controls. Patient controls may even be preferable from population controls under certain conditions. In this study we examine if colon cancer patients can serve as surrogates for proper population controls in case-control studies of occupational risk factors. Methods The study was conducted from 1995 to 1997. Incident colon cancer controls (N = 428 aged 35–69 years with a histological verified diagnosis and population controls (N = 583 were selected. Altogether 254 (59% of the colon cancer controls and 320 (55% of the population controls were interviewed about occupational, medical and life style conditions. Results No statistical significant difference for educational level, medical history or smoking status was seen between the two control groups. There was evidence of a higher alcohol intake, less frequent work as a farmer and less exposure to pesticides among colon cancer controls. Conclusions Use of colon cancer controls may provide valid exposure estimates in studies of many occupational risk factors for cancer, but not for studies on exposure related to farming.

  11. Microbial existence in controlled habitats and their resistance to space conditions.

    Science.gov (United States)

    Venkateswaran, Kasthuri; La Duc, Myron T; Horneck, Gerda

    2014-09-17

    The National Research Council (NRC) has recently recognized the International Space Station (ISS) as uniquely suitable for furthering the study of microbial species in closed habitats. Answering the NRC's call for the study, in particular, of uncommon microbial species in the ISS, and/or of those that have significantly increased or decreased in number, space microbiologists have begun capitalizing on the maturity, speed, and cost-effectiveness of molecular/genomic microbiological technologies to elucidate changes in microbial populations in the ISS and other closed habitats. Since investigators can only collect samples infrequently from the ISS itself due to logistical reasons, Earth analogs, such as spacecraft-assembly clean rooms, are used and extensively characterized for the presence of microbes. Microbiologists identify the predominant, problematic, and extremophilic microbial species in these closed habitats and use the ISS as a testbed to study their resistance to extreme extraterrestrial environmental conditions. Investigators monitor the microbes exposed to the real space conditions in order to track their genomic changes in response to the selective pressures present in outer space (external to the ISS) and the spaceflight (in the interior of the ISS). In this review, we discussed the presence of microbes in space research-related closed habitats and the resistance of some microbial species to the extreme environmental conditions of space.

  12. Key design factors affecting microbial community composition and pathogenic organism removal in horizontal subsurface flow constructed wetlands.

    Science.gov (United States)

    Morató, Jordi; Codony, Francesc; Sánchez, Olga; Pérez, Leonardo Martín; García, Joan; Mas, Jordi

    2014-05-15

    Constructed wetlands constitute an interesting option for wastewater reuse since high concentrations of contaminants and pathogenic microorganisms can be removed with these natural treatment systems. In this work, the role of key design factors which could affect microbial removal and wetland performance, such as granular media, water depth and season effect was evaluated in a pilot system consisting of eight parallel horizontal subsurface flow (HSSF) constructed wetlands treating urban wastewater from Les Franqueses del Vallès (Barcelona, Spain). Gravel biofilm as well as influent and effluent water samples of these systems were taken in order to detect the presence of bacterial indicators such as total coliforms (TC), Escherichia coli, fecal enterococci (FE), Clostridium perfringens, and other microbial groups such as Pseudomonas and Aeromonas. The overall microbial inactivation ratio ranged between 1.4 and 2.9 log-units for heterotrophic plate counts (HPC), from 1.2 to 2.2 log units for total coliforms (TC) and from 1.4 to 2.3 log units for E. coli. The presence of fine granulometry strongly influenced the removal of all the bacterial groups analyzed. This effect was significant for TC (p=0.009), E. coli (p=0.004), and FE (p=0.012). Shallow HSSF constructed wetlands were more effective for removing Clostridium spores (p=0.039), and were also more efficient for removing TC (p=0.011) and E. coli (p=0.013) when fine granulometry was used. On the other hand, changes in the total bacterial community from gravel biofilm were examined by using denaturing gradient gel electrophoresis (DGGE) and sequencing of polymerase chain reaction (PCR)-amplified fragments of the 16S rRNA gene recovered from DGGE bands. Cluster analysis of the DGGE banding pattern from the different wetlands showed that microbial assemblages separated according to water depth, and sequences of different phylogenetic groups, such as Alpha, Beta and Delta-Proteobacteria, Nitrospirae, Bacteroidetes

  13. Recombinant expression and anti-microbial activity of anti-lipopolysaccharide factor (ALF) from the black tiger shrimp Penaeus monodon.

    Science.gov (United States)

    Somboonwiwat, Kunlaya; Marcos, Michael; Tassanakajon, Anchalee; Klinbunga, Sirawut; Aumelas, André; Romestand, Bernard; Gueguen, Yannick; Boze, Hélène; Moulin, Guy; Bachère, Evelyne

    2005-01-01

    Anti-lipopolysaccharide factors (ALFs), originally characterized from horseshoe crabs, have been recently identified from hemocytes of the black tiger shrimp, Penaeus monodon, by a genomic approach. In order to characterize the properties and biological activities of this immune effector in shrimp, ALFPm3, the most abundant isoform found in P. monodon, was expressed in the yeast Pichia pastoris. Large-scale production in fermentor provided 262 mg/l of recombinant ALFPm3 which was purified to homogeneity by single chromatography step on expanded-bed Streamline SP6XL. The rALFPm3 was further characterized in terms of N-terminal sequencing and mass spectrometry. Anti-microbial assays demonstrated that rALFPm3 has a broad spectrum of anti-fungal properties against filamentous fungi, and anti-bacterial activities against both Gram-positive and Gram-negative bacteria, associated with a bactericidal effect. Interestingly, rALFPm3 is highly efficient against various Vibrio species including strains pathogenic for shrimp. Finally, a synthetic peptide corresponding to a part of the putative LPS-binding site of ALFPm3 was shown to display activities mainly directed against Gram-positive bacteria indicating the involvement of the full molecule to the anti-microbial activity for Gram-negative bacteria.

  14. Factors influencing the microbial composition of metalworking fluids and potential implications for machine operator's lung.

    Science.gov (United States)

    Murat, Jean-Benjamin; Grenouillet, Frédéric; Reboux, Gabriel; Penven, Emmanuelle; Batchili, Adam; Dalphin, Jean-Charles; Thaon, Isabelle; Millon, Laurence

    2012-01-01

    Hypersensitivity pneumonitis, also known as "machine operator's lung" (MOL), has been related to microorganisms growing in metalworking fluids (MWFs), especially Mycobacterium immunogenum. We aimed to (i) describe the microbiological contamination of MWFs and (ii) look for chemical, physical, and environmental parameters associated with variations in microbiological profiles. We microbiologically analyzed 180 MWF samples from nonautomotive plants (e.g., screw-machining or metal-cutting plants) in the Franche-Comté region in eastern France and 165 samples from three French automotive plants in which cases of MOL had been proven. Our results revealed two types of microbial biomes: the first was from the nonautomotive industry, showed predominantly Gram-negative rods (GNR), and was associated with a low risk of MOL, and the second came from the automotive industry that was affected by cases of MOL and showed predominantly Gram-positive rods (GPR). Traces of M. immunogenum were sporadically detected in the first type, while it was highly prevalent in the automotive sector, with up to 38% of samples testing positive. The use of chromium, nickel, or iron was associated with growth of Gram-negative rods; conversely, growth of Gram-positive rods was associated with the absence of these metals. Synthetic MWFs were more frequently sterile than emulsions. Vegetable oil-based emulsions were associated with GNR, while mineral ones were associated with GPR. Our results suggest that metal types and the nature of MWF play a part in MWF contamination, and this work shall be followed by further in vitro simulation experiments on the kinetics of microbial populations, focusing on the phenomena of inhibition and synergy.

  15. Biodegradation: Updating the Concepts of Control for Microbial Cleanup in Contaminated Aquifers

    DEFF Research Database (Denmark)

    Meckenstock, Rainer U.; Elsner, Martin; Griebler, Christian

    2015-01-01

    Biodegradation is one of the most favored and sustainable means of removing organic pollutants from contaminated aquifers but the major steering factors are still surprisingly poorly understood. Growing evidence questions some of the established concepts for control of biodegradation. Here, we...... critically discuss classical concepts such as the thermodynamic redox zonation, or the use of steady state transport scenarios for assessing biodegradation rates. Furthermore, we discuss if the absence of specific degrader populations can explain poor biodegradation. We propose updated perspectives...

  16. Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments

    DEFF Research Database (Denmark)

    Rousk, Kathrin; Michelsen, Anders; Rousk, Johannes

    2016-01-01

    investigated how warming (+1.1 °C over ambient using open top chambers) and litter addition (90 g m−2 yr−1) treatments in the subarctic influenced the susceptibility of SOM mineralization to priming, and its microbial underpinnings. Labile C appeared to inhibit the mineralization of C from SOM by up to 60......% within hours. In contrast, the mineralization of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile C inhibited C mineralization is compatible with previously......: This suggested that the microbial SOM-use decreased in magnitude and shifted to components richer in N. This finding highlights that only considering SOM in terms of C may be simplistic, and will not capture all changes in SOM decomposition. The selective mining for N increased in climate change treatments...

  17. Microbial Fluid-Rock Interactions in Chalk Samples and Salinity Factor in Divalent Ca2+ ions Release for Microbial Enhanced Oil Recovery Purposes

    DEFF Research Database (Denmark)

    Jimoh, Ismaila Adetunji; Rudyk, Svetlana Nikolayevna; Søgaard, Erik Gydesen

    2011-01-01

    In this study, laboratory experiments were performed on chalk samples from Danish sector of the North Sea to study microbial fluid-rock interactions with carbonate rock and to evaluate the dissolution of rock matrix (CaCO3). Result showed that the average concentration of Ca2+ ions after microbial...... fluid interactions with chalk samples in media of salinity 40-100g/l increased from initial average concentration of 203 mg/l at the start of the experiment to 1178 mg/l in 28 days. 3-D surface plot (salinity, Ca2+, pH) with time revealed delineation of the measured salinity into two groups...

  18. High arsenic (As concentrations in the shallow groundwaters of southern Louisiana: Evidence of microbial controls on As mobilization from sediments

    Directory of Open Access Journals (Sweden)

    Ningfang Yang

    2016-03-01

    New hydrological insights for the region: Shallow groundwaters in southern Louisiana have been reported to contain elevated As concentrations, whereas mechanisms responsible for As release from sediments have rarely been studied in this region. Microbial respiration is generally considered the main mechanism controlling As release in reducing anoxic aquifers such as the shallow aquifers in southern Louisiana and those of the Bengal basin. This study investigates the role microbial respiration plays in As release from shallow aquifer sediments in southern Louisiana through sediment incubation experiments and porewater analysis. Arsenic concentrations were the lowest in the sterilized control experiments, slightly higher in the un-amended experiments, and the highest in the experiments amended with acetate, and especially those amended with both acetate and AQDS (9,10-anthraquinone-2,6-disulfonic acid. Although Fe and Mn generally decreased at the beginning of all the experiments, they did follow a similar trend to As after the decrease. Porewater analysis showed that As and Fe concentrations were generally positively correlated and were higher in the coarse-grained sediments than in the fine-grained sediments. Results of the investigation are consistent with microbial respiration playing a key role in As release from the shallow aquifers sediments in southern Louisiana.

  19. Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids; Part I. Effects on growth performance, microbial populations and immune status

    Science.gov (United States)

    Pigs (n=88) weaned at 19 ± 2 d of age were used in a 14 d study to evaluate the effects of water-delivered direct-fed microbials (DFM) or organic acids on immune status, Salmonella infection and shedding, and intestinal microbial populations following a Salmonella Typhimurium challenge. Pigs were ch...

  20. 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

    Current approaches such as inspections, audits, and end product testing cannot detect the distribution and dynamics of microbial contamination. Despite the implementation of current food safety management systems, foodborne outbreaks linked to fresh produce continue to be reported. A microbial as...

  1. Physical and Geochemical Controls on the Structure and Function of Microbial Mat Communities at El Tatio Geyser Field, Chile

    Science.gov (United States)

    Myers, K. D.; Omelon, C. R.; Bennett, P.

    2013-12-01

    Cyanobacteria are important primary producers that form the basis of most hot spring microbial mat communities in waters between 30-73°C. Primary producers shape microbial mat communities by fixing the dissolved inorganic carbon (DIC) pool to organic carbon and providing nutrients for diverse microorganisms that perform a broad range of biogeochemical transformations. This study compares the microbial community structure and net primary productivity of cyanobacterially-based and non-cyanobacterially based microbial mats collected from the El Tatio Geyser Field, a high elevation geyser complex in the Andes Mountains in Region II, Chile. In addition to extreme conditions imparted by high elevation and its location in the Atacama Desert, El Tatio has a suite of extreme geochemical stressors for life, including high arsenic as As(III) and As(V) (0.4-0.6 mM). El Tatio also has unusually low concentrations of DIC in some streams (0.1-0.3 mM), low enough to severely limit primary production in microbial mats. In contrast to other geothermal sites around the world where microbial diversity is controlled primarily by temperature, observations of unusual patterns in microbial mat composition in low-DIC streams at El Tatio suggest alternate controls their distribution. For instance, we observe less biomass in low-DIC streams compared to nearby high DIC streams, and less biomass in high temperature regions of low-DIC streams, compared to low-temperature locations that are dominated by cyanobacteria. To further investigate these patterns, a field assay was conducted to compare carbon assimilation, the relative importance of photo- and chemoautotrophy, and bacterial 16S rRNA sequence abundance at two distinct sites along a low-DIC stream. Water temperature at the upstream site measured 60°C, is dominated by high As(III), and is composed of sparse, red-colored mat material, whereas the downstream site measured a water temperature of 40°C, is dominated by high As(V), and is

  2. A study of microbial population dynamics associated with corrosion rates influenced by corrosion control materials

    NARCIS (Netherlands)

    Chang, Yu Jie; Hung, Chun Hsiung; Lee, Jyh Wei; Chang, Yi Tang; Lin, Fen Yu; Chuang, Chun Jie

    2015-01-01

    This research aims to analyze the variations of microbial community structure under anaerobic corrosive conditions, using molecular fingerprinting method. The effect of adding various materials to the environment on the corrosion mechanism has been discussed. In the initial experiment, sulfate-re

  3. A study of microbial population dynamics associated with corrosion rates influenced by corrosion control materials

    NARCIS (Netherlands)

    Chang, Yu Jie; Hung, Chun Hsiung; Lee, Jyh Wei; Chang, Yi Tang; Lin, Fen Yu; Chuang, Chun Jie

    2015-01-01

    This research aims to analyze the variations of microbial community structure under anaerobic corrosive conditions, using molecular fingerprinting method. The effect of adding various materials to the environment on the corrosion mechanism has been discussed. In the initial experiment,

  4. Soil biochemical properties and microbial resilience in agroforestry systems: effects on wheat growth under controlled drought and flooding conditions.

    Science.gov (United States)

    Rivest, David; Lorente, Miren; Olivier, Alain; Messier, Christian

    2013-10-01

    Agroforestry is increasingly viewed as an effective means of maintaining or even increasing crop and tree productivity under climate change while promoting other ecosystem functions and services. This study focused on soil biochemical properties and resilience following disturbance within agroforestry and conventional agricultural systems and aimed to determine whether soil differences in terms of these biochemical properties and resilience would subsequently affect crop productivity under extreme soil water conditions. Two research sites that had been established on agricultural land were selected for this study. The first site included an 18-year-old windbreak, while the second site consisted in an 8-year-old tree-based intercropping system. In each site, soil samples were used for the determination of soil nutrient availability, microbial dynamics and microbial resilience to different wetting-drying perturbations and for a greenhouse pot experiment with wheat. Drying and flooding were selected as water stress treatments and compared to a control. These treatments were initiated at the beginning of the wheat anthesis period and maintained over 10 days. Trees contributed to increase soil nutrient pools, as evidenced by the higher extractable-P (both sites), and the higher total N and mineralizable N (tree-based intercropping site) found in the agroforestry compared to the conventional agricultural system. Metabolic quotient (qCO2) was lower in the agroforestry than in the conventional agricultural system, suggesting higher microbial substrate use efficiency in agroforestry systems. Microbial resilience was higher in the agroforestry soils compared to soils from the conventional agricultural system (windbreak site only). At the windbreak site, wheat growing in soils from agroforestry system exhibited higher aboveground biomass and number of grains per spike than in conventional agricultural system soils in the three water stress treatments. At the tree

  5. Power factor control system for ac induction motors

    Science.gov (United States)

    Nola, F. J. (Inventor)

    1981-01-01

    A power control circuit for an induction motor is disclosed in which a servo loop is used to control power input by controlling the power factor of motor operation. The power factor is measured by summing the voltage and current derived square wave signals.

  6. Microorganisms in Confined Habitats: Microbial Monitoring and Control of Intensive Care Units, Operating Rooms, Cleanrooms and the International Space Station.

    Science.gov (United States)

    Mora, Maximilian; Mahnert, Alexander; Koskinen, Kaisa; Pausan, Manuela R; Oberauner-Wappis, Lisa; Krause, Robert; Perras, Alexandra K; Gorkiewicz, Gregor; Berg, Gabriele; Moissl-Eichinger, Christine

    2016-01-01

    Indoor environments, where people spend most of their time, are characterized by a specific microbial community, the indoor microbiome. Most indoor environments are connected to the natural environment by high ventilation, but some habitats are more confined: intensive care units, operating rooms, cleanrooms and the international space station (ISS) are extraordinary living and working areas for humans, with a limited exchange with the environment. The purposes for confinement are different: a patient has to be protected from infections (intensive care unit, operating room), product quality has to be assured (cleanrooms), or confinement is necessary due to extreme, health-threatening outer conditions, as on the ISS. The ISS represents the most secluded man-made habitat, constantly inhabited by humans since November 2000 - and, inevitably, also by microorganisms. All of these man-made confined habitats need to be microbiologically monitored and controlled, by e.g., microbial cleaning and disinfection. However, these measures apply constant selective pressures, which support microbes with resistance capacities against antibiotics or chemical and physical stresses and thus facilitate the rise of survival specialists and multi-resistant strains. In this article, we summarize the available data on the microbiome of aforementioned confined habitats. By comparing the different operating, maintenance and monitoring procedures as well as microbial communities therein, we emphasize the importance to properly understand the effects of confinement on the microbial diversity, the possible risks represented by some of these microorganisms and by the evolution of (antibiotic) resistances in such environments - and the need to reassess the current hygiene standards.

  7. Microorganisms in confined habitats: Microbial monitoring and control of intensive care units, operating rooms, cleanrooms and the International Space Station

    Directory of Open Access Journals (Sweden)

    Maximilian Mora

    2016-10-01

    Full Text Available Indoor environments, where people spend most of their time, are characterized by a specific microbial community, the indoor microbiome. Most indoor environments are connected to the natural environment by high ventilation, but some habitats are more confined: intensive care units, operating rooms, cleanrooms and the international space station (ISS are extraordinary living and working areas for humans, with a limited exchange with the environment. The purposes for confinement are different: a patient has to be protected from infections (intensive care unit, operating room, product quality has to be assured (cleanrooms, or confinement is necessary due to extreme, health-threatening outer conditions, as on the ISS. The ISS represents the most secluded man-made habitat, constantly inhabited by humans since November 2000 – and, inevitably, also by microorganisms. All of these man-made confined habitats need to be microbiologically monitored and controlled, by e.g. microbial cleaning and disinfection. However, these measures apply constant selective pressures, which support microbes with resistance capacities against antibiotics or chemical and physical stresses and thus facilitate the rise of survival specialists and multi-resistant strains. In this article, we summarize the available data on the microbiome of aforementioned confined habitats. By comparing the different operating, maintenance and monitoring procedures as well as microbial communities therein, we emphasize the importance to properly understand the effects of confinement on the microbial diversity, the possible risks represented by some of these microorganisms and by the evolution of (antibiotic resistances in such environments - and the need to reassess the current hygiene standards.

  8. Using Plant Phylogenetic Relatedness as a Predictor for Plants' Control on Soil Microbial Communities and Nitrogen Cycling

    Science.gov (United States)

    Potter, T.; Bowman, W. D.

    2016-12-01

    Despite the known importance of soil microbes and their influence on soil processes, a mechanistic understanding is still needed to predict how plants and soil microbes interact at scales that are relevant to community and ecosystem-scale processes. Closely related plant species have similar traits aboveground, but we don't know whether this is also true for belowground traits that affect soil microbial community structure and function. Determining how tightly plant phylogeny and plant functional traits are linked to soil microbial communities is a useful approach for discovering plant-microbe associations that are generalizable across plant species (a limitation of studies that employ a single or few plant species). Using this approach, we conducted a greenhouse study with seven congeneric grasses (genus Poa) and their native soils to examine whether plants' influences on microbial community structure were consistent with plant phylogenetic relatedness and/or plant functional traits. Seeds of each Poa species were planted in native soil (from the seed source population) as well as a homogenized soil from all seven populations. Additionally, a nitrogen treatment was added to address how an environmental change (such as nitrogen deposition) alters plant-microbe associations. Rhizosphere community composition of bacteria and fungi was obtained via marker gene sequencing to compare community composition across plant species. Patterns in plant-microbe associations across plant species reveal plant control on nutrient cycling via plant species' influence on microbial community structure. These results determine if we are ready to generalize about plant-microbe interactions at the genus level, an important stepping-stone to applying knowledge of plant-microbe interactions to larger ecological scales.

  9. Underlying Factors for Practicality of the Production Control Systems

    DEFF Research Database (Denmark)

    Arica, Emrah; Strandhagen, Jan Ola; Hvolby, Hans-Henrik

    2012-01-01

    This paper gives indications to important factors that must be considered for effectiveness of the production control systems under uncertainty. Five key factors have been identified by the literature study. Production schedule generation and execution approach under uncertainty, information...

  10. Improving tuberculosis infection control practice and micro-bial air quality in a general hospital after intervention

    Institute of Scientific and Technical Information of China (English)

    Pipat Luksamijarulkul; Jiraporn Khumsri; Pisit Vatthanasomboon; Pornapa Aiumlaor

    2009-01-01

    Objective:Hospital personnel,especially nurses are at risk for tuberculosis(TB)infection and the intervention for reducing the risk should be established.Methods:To compare the TB infection control practices and stand-ard precaution in 154 registered nurses and auxiliary nurses working in risk wards.Additionally,microbial air quality in the studied wards was investigated before and after implementation of an intervention including two-day training program on TB infection control and standard precaution practices and managing the ward environ-ments.Results:Post-intervention,the percentage of studied nurses who always practiced increased in every i-tem of TB infection control practice (6 items)and standard precaution (9 items)when compared with the pre-intervention period.Both mean scores were significantly higher than those before intervention (5.0 ±1.0 vs 4. 4 ±1.1,and 7.6 ±1.3 vs 6.7 ±1.5,P 500 cfu /m3 ).Conclusion:Two-day training program and management of the ward environment could improve the scores of TB infection control practices and the standard precaution among studied nurses and reduce the microbial counts in air samples col-lected from the studied wards.

  11. Microbial Community Assessment in Wetlands for Water Pollution Control: Past, Present, and Future Outlook

    Directory of Open Access Journals (Sweden)

    Kela P. Weber

    2016-11-01

    Full Text Available The field of treatment wetlands (TWs is rapidly expanding and, arguably, is tasked with studying and understanding one of the most complex water treatment systems available. Microbial communities are generally considered to be responsible for the majority of wastewater constituent degradation in TWs. However, they are also known to be spatially heterogeneous, temporally dynamic, as well as structurally and functionally diverse. Presented here is a meta-analysis of all peer reviewed TW journal articles which utilized a microbial community assessment methodology over the period of 1988 to July 2016. A total of 1101 papers were reviewed, 512 from 1988 to 2012, 215 of which included a microbial community assessment aspect and were subsequently classified as representing past research, and 589 from 2013 to July 2016, 196 of which were classified as representing current TW microbial community research. In general, TW microbial community research has increased over time, with a marked surge in the past four years. Microbial community structure is currently the most commonly used methodological type followed by activity, enumeration and function, respectively. Areas of research focus included nitrogen transformations (156, organic degradation (33, and emerging contaminants (32, with general characterization studies also accounting for a significant proportion (243. Microbial communities from a range of TW systems have been investigated over the last four years with meso-scale (10–1000 L being the most commonly studied system size followed by large-scale (>100,000 L, micro-scale (<10 L, and pilot-scale (1000–100,000 L. Free water surface flow (SF, horizontal subsurface flow (HF, and vertical flow (VF systems are being studied in approximately equal proportions with the majority of studies focused on gaining fixed media/biofilm samples for analysis (rather than from the rhizosphere or interstitial water. Looking at efforts from a regional perspective

  12. Control of temperature on microbial community structure in hot springs of the Tibetan Plateau.

    Science.gov (United States)

    Wang, Shang; Hou, Weiguo; Dong, Hailiang; Jiang, Hongchen; Huang, Liuqin; Wu, Geng; Zhang, Chuanlun; Song, Zhaoqi; Zhang, Yong; Ren, Huilei; Zhang, Jing; Zhang, Li

    2013-01-01

    The Tibetan Plateau in Northwest China hosts a number of hot springs that represent a biodiversity hotspot for thermophiles, yet their diversity and relationship to environmental conditions are poorly explored in these habitats. In this study we investigated microbial diversity and community composition in 13 Tibetan hot springs with a wide range of temperatures (22.1-75°C) and other geochemical conditions by using the 16S rRNA gene pyrosequencing approach. Bacteria (10(8)-10(11) copy/g; 42 bacterial phyla) in Tibetan hot springs were more abundant and far more diverse than Archaea (10(7)-10(10) copy/g; 5 archaeal phyla). The dominant bacterial phyla systematically varied with temperature. Moderate temperatures (75-66°C) favored Aquificae, GAL35, and novel Bacteria, whereas low temperatures (60-22.1°C) selected for Deinococcus-Thermus, Cyanobacteria, and Chloroflexi. The relative abundance of Aquificae was correlated positively with temperature, but the abundances of Deinococcus-Thermus, Cyanobacteria, and Chloroflexi were negatively correlated with temperature. Cyanobacteria and Chloroflexi were abundant in Tibetan hot springs and their abundances were positively correlated at low temperatures (55-43°C) but negatively correlated at moderate temperatures (75-55°C). These correlation patterns suggest a complex physiological relationship between these two phyla. Most archaeal sequences were related to Crenarchaeota with only a few related to Euryarchaeota and Thaumarchaeota. Despite the fact that microbial composition in Tibetan hot springs was strongly shaped by temperature, microbial diversity (richness, evenness and Shannon diversity) was not significantly correlated with temperature change. The results of this study expand our current understanding of microbial ecology in Tibetan hot springs and provide a basis for a global comparison.

  13. Photoautotrophic organisms control microbial abundance and diversity in biological soil crusts

    Science.gov (United States)

    Tamm, Alexandra; Maier, Stefanie; Wu, Dianming; Caesar, Jennifer; Hoffman, Timm; Grube, Martin; Weber, Bettina

    2017-04-01

    Vascular vegetation is typically quite sparse or even absent in dryland ecosystems all over the world, but the ground surface is not bare and largely covered by biological soil crusts (referred to as biocrusts hereafter). These biocrust communities generally comprise poikilohydric organisms. They are usually dominated by photoautotrophic cyanobacteria, lichens and mosses, growing together with heterotrophic fungi, bacteria and archaea in varying composition. Cyanobacteria-, lichen- and moss-dominated biocrusts are known to stabilize the soil and to influence the water budgets and plant establishment. The autotrophic organisms take up atmospheric CO2, and (cyano-)bacteria fix atmospheric nitrogen. The intention of the present project was to study the relevance of the dominating photoautotrophic organisms for biocrust microbial composition and physiology. High-throughput sequencing revealed that soil microbiota of biocrusts largely differ from the bacterial community in bare soil. We observed that bacterial and fungal abundance (16S and 18S rRNA gene copy numbers) as well as alpha diversity was lowest in bare soil, and increasing from cyanobacteria-, and chlorolichen- to moss-dominated biocrusts. CO2 gas exchange measurements revealed large respiration rates of the soil in moss-dominated biocrusts, which was not observed for cyanobacteria- and chlorolichen-dominated biocrusts. Thus, soil respiration of moss-dominated biocrusts is mainly due to the activity of the microbial communities, whereas the microorganisms in the other biocrust types are either dormant or feature functionally different microbial communities. Our results indicate that biocrust type determines the pattern of microbial communities in the underlying soil layer.

  14. Controlling accumulation of fermentation inhibitors in biorefinery recycle water using microbial fuel cells

    Science.gov (United States)

    Borole, Abhijeet P; Mielenz, Jonathan R; Vishnivetskaya, Tatiana A; Hamilton, Choo Y

    2009-01-01

    Background Microbial fuel cells (MFC) and microbial electrolysis cells are electrical devices that treat water using microorganisms and convert soluble organic matter into electricity and hydrogen, respectively. Emerging cellulosic biorefineries are expected to use large amounts of water during production of ethanol. Pretreatment of cellulosic biomass results in production of fermentation inhibitors which accumulate in process water and make the water recycle process difficult. Use of MFCs to remove the inhibitory sugar and lignin degradation products from recycle water is investigated in this study. Results Use of an MFC to reduce the levels of furfural, 5-hydroxymethylfurfural, vanillic acid, 4-hydroxybenzaldehyde and 4-hydroxyacetophenone while simultaneously producing electricity is demonstrated here. An integrated MFC design approach was used which resulted in high power densities for the MFC, reaching up to 3700 mW/m2 (356 W/m3 net anode volume) and a coulombic efficiency of 69%. The exoelectrogenic microbial consortium enriched in the anode was characterized using a 16S rRNA clone library method. A unique exoelectrogenic microbial consortium dominated by δ-Proteobacteria (50%), along with β-Proteobacteria (28%), α-Proteobacteria (14%), γ-Proteobacteria (6%) and others was identified. The consortium demonstrated broad substrate specificity, ability to handle high inhibitor concentrations (5 to 20 mM) with near complete removal, while maintaining long-term stability with respect to power production. Conclusion Use of MFCs for removing fermentation inhibitors has implications for: 1) enabling higher ethanol yields at high biomass loading in cellulosic ethanol biorefineries, 2) improved water recycle and 3) electricity production up to 25% of total biorefinery power needs. PMID:19338657

  15. Controlling accumulation of fermentation inhibitors in biorefinery recycle water using microbial fuel cells

    Directory of Open Access Journals (Sweden)

    Vishnivetskaya Tatiana A

    2009-04-01

    Full Text Available Abstract Background Microbial fuel cells (MFC and microbial electrolysis cells are electrical devices that treat water using microorganisms and convert soluble organic matter into electricity and hydrogen, respectively. Emerging cellulosic biorefineries are expected to use large amounts of water during production of ethanol. Pretreatment of cellulosic biomass results in production of fermentation inhibitors which accumulate in process water and make the water recycle process difficult. Use of MFCs to remove the inhibitory sugar and lignin degradation products from recycle water is investigated in this study. Results Use of an MFC to reduce the levels of furfural, 5-hydroxymethylfurfural, vanillic acid, 4-hydroxybenzaldehyde and 4-hydroxyacetophenone while simultaneously producing electricity is demonstrated here. An integrated MFC design approach was used which resulted in high power densities for the MFC, reaching up to 3700 mW/m2 (356 W/m3 net anode volume and a coulombic efficiency of 69%. The exoelectrogenic microbial consortium enriched in the anode was characterized using a 16S rRNA clone library method. A unique exoelectrogenic microbial consortium dominated by δ-Proteobacteria (50%, along with β-Proteobacteria (28%, α-Proteobacteria (14%, γ-Proteobacteria (6% and others was identified. The consortium demonstrated broad substrate specificity, ability to handle high inhibitor concentrations (5 to 20 mM with near complete removal, while maintaining long-term stability with respect to power production. Conclusion Use of MFCs for removing fermentation inhibitors has implications for: 1 enabling higher ethanol yields at high biomass loading in cellulosic ethanol biorefineries, 2 improved water recycle and 3 electricity production up to 25% of total biorefinery power needs.

  16. Control of temperature on microbial community structure in hot springs of the Tibetan Plateau.

    Directory of Open Access Journals (Sweden)

    Shang Wang

    Full Text Available The Tibetan Plateau in Northwest China hosts a number of hot springs that represent a biodiversity hotspot for thermophiles, yet their diversity and relationship to environmental conditions are poorly explored in these habitats. In this study we investigated microbial diversity and community composition in 13 Tibetan hot springs with a wide range of temperatures (22.1-75°C and other geochemical conditions by using the 16S rRNA gene pyrosequencing approach. Bacteria (10(8-10(11 copy/g; 42 bacterial phyla in Tibetan hot springs were more abundant and far more diverse than Archaea (10(7-10(10 copy/g; 5 archaeal phyla. The dominant bacterial phyla systematically varied with temperature. Moderate temperatures (75-66°C favored Aquificae, GAL35, and novel Bacteria, whereas low temperatures (60-22.1°C selected for Deinococcus-Thermus, Cyanobacteria, and Chloroflexi. The relative abundance of Aquificae was correlated positively with temperature, but the abundances of Deinococcus-Thermus, Cyanobacteria, and Chloroflexi were negatively correlated with temperature. Cyanobacteria and Chloroflexi were abundant in Tibetan hot springs and their abundances were positively correlated at low temperatures (55-43°C but negatively correlated at moderate temperatures (75-55°C. These correlation patterns suggest a complex physiological relationship between these two phyla. Most archaeal sequences were related to Crenarchaeota with only a few related to Euryarchaeota and Thaumarchaeota. Despite the fact that microbial composition in Tibetan hot springs was strongly shaped by temperature, microbial diversity (richness, evenness and Shannon diversity was not significantly correlated with temperature change. The results of this study expand our current understanding of microbial ecology in Tibetan hot springs and provide a basis for a global comparison.

  17. 食品的 pH 值与微生物控制%PH value and microbial control of food

    Institute of Scientific and Technical Information of China (English)

    赵君哲

    2015-01-01

    介绍了食品中 pH 值对微生物的影响;酸性食品与低酸性食品的不同,以及对微生物控制的操作差异。%The effect of the pH value of food on microbial was introduced. The difference of acid food and low acidity food and the different operation of microbial control were studied.

  18. Viral infections as controlling factors for the deep biosphere? (Invited)

    Science.gov (United States)

    Engelen, B.; Engelhardt, T.; Sahlberg, M.; Cypionka, H.

    2009-12-01

    The marine deep biosphere represents the largest biotope on Earth. Throughout the last years, we have obtained interesting insights into its microbial community composition. However, one component that was completely overlooked so far is the viral inventory of deep-subsurface sediments. While viral infections were identified to have a major impact on the benthic microflora of deep-sea surface sediments (Danavaro et al. 2008), no studies were performed on deep-biosphere samples, so far. As grazers probably play only a minor role in anoxic and highly compressed deep sediments, viruses might be the main “predators” for indigenous microorganisms. Furthermore, the release of cell components, called “the viral shunt”, could have a major impact on the deep biosphere in providing labile organic compounds to non-infected microorganisms in these generally nutrient depleted sediments. However, direct counting of viruses in sediments is highly challenging due to the small size of viruses and the high background of small particles. Even molecular surveys using “universal” PCR primers that target phage-specific genes fail due to the vast phage diversity. One solution for this problem is the lysogenic viral life cycle as many bacteriophages integrate their DNA into the host genome. It is estimated that up to 70% of cultivated bacteria contain prophages within their genome. Therefore, culture collections (Batzke et al. 2007) represent an archive of the viral composition within the respective habitat. These prophages can be induced to become free phage particles in stimulation experiments in which the host cells are set under certain stress situations such as a treatment with UV exposure or DNA-damaging antibiotics. The study of the viral component within the deep biosphere offers to answer the following questions: To which extent are deep-biosphere populations controlled by viral infections? What is the inter- and intra-specific diversity and the host-specific viral

  19. Risk factors, microbiological findings, and clinical outcomes in cases of microbial keratitis admitted to a tertiary referral center in ireland.

    LENUS (Irish Health Repository)

    Saeed, Ayman

    2012-02-01

    AIM: To identify the risk factors for, and to report the microbiological findings and clinical outcomes of, severe microbial keratitis (MK). METHODS: This was a retrospective study of all cases of presumed MK admitted to a tertiary referral center over a 2-year period (September 2001 to August 2003). Data recorded included demographic data, details relating to possible risk factors, results of microbiological studies, clinical findings at presentation, and clinical and visual outcomes. RESULTS: Ninety patients were admitted with a diagnosis of presumed MK during the study period. The mean age of patients was 45 +\\/- 32 years, and the male to female ratio was 47:43 (52.2%:47.7%). Predisposing risk factors for MK included contact lens wear (37; 41.1%), anterior segment disease (19; 21.1%), ocular trauma (13; 14.4%), systemic disease (5; 5.6%), and previous ocular surgery (1; 1.1%). Cultured organisms included gram-negative bacteria (17; 51.5%), gram-positive bacteria (11, 33.3%), acanthamoeba (2; 6.1%), and fungi (1; 3%). Visual acuity improved significantly after treatment [mean best-corrected visual acuity (+\\/-standard deviation) at presentation: 0.76 (+\\/-0.11); mean best-corrected visual acuity at last follow-up: 0.24 (+\\/-0.07); P < 0.001]. Secondary surgical procedures were required in 18 (20%) cases, and these included punctal cautery (1; 1.1%), tissue glue repair of corneal perforation (2; 2.2%), tarsorrhaphy (9; 9.9%), Botulinum toxin-induced ptosis (1; 1.1%), penetrating keratoplasty (3; 3.3%), and evisceration (2; 2.2%). CONCLUSIONS: Contact lens wear remains a significant risk factor for severe MK. MK remains a threat to vision and to the eye, but the majority of cases respond to prompt and appropriate antimicrobial therapy.

  20. Dispersive Mixing? Mass Transfer? Microbial Dynamics? Potential Controls of Bioreactive Transport

    Science.gov (United States)

    Cirpka, O. A.; Loschko, M.; Eckert, D.; Mellage, A.

    2016-12-01

    Mixing-controlled reactive transport, in which compounds A and B must come together to react, has gained significant attention in the past years. The goal is to formulate upscaled, effective equations of reactive transport in physically and chemically heterogeneous media without fully resolving the heterogeneity. Towards this end, it is important to analyze which processes control the overall reactive behavior. The presentation classifies potential controls of (bio)reactive transport into several categories, for which different effective transport equations may be derived. The replacement scenario (solution of B replaces the solution of A) has become a popular target to study fundamental aspects of dispersive mixing. In most cases, it s assumed that neither A nor B sorb. Under such conditions, the reaction is controlled by macroscopic longitudinal dispersive mixing, which is controlled by variability of velocity and micro-scale transverse mixing. However, in most practical applications, at least one of the two compounds sorbs. If A sorbs more strongly than B, chromatographic mixing will always dominate over dispersive mixing at late times. A second popular scenario is a continuously released plume of A, reacting with B provided by ambient flow. This system is controlled by macroscopic transverse dispersion, which increases much less than longitudinal mixing in heterogeneous domains. Transient flow leads to some additional enhancement, but not very much. If the compounds sorb differently, transient flow causes alternating chromatographic mixing and separation. Many contaminants react with the aquifer matrix. In these cases, dispersive mixing is merely a nuisance, and the controling factor is the release of the reaction partner from the matrix. Here, travel-time based approaches work if chemical heterogeneity can be excluded. To account for the latter, one can integrate the time of exposure to reactive materials, eventually scaled by the intensity of the reaction, to

  1. PMBLDC motor drive with power factor correction controller

    DEFF Research Database (Denmark)

    George, G.J.; Ramachandran, Rakesh; Arun, N.

    2012-01-01

    This paper presents a boost converter configuration, control scheme and design of single phase power factor controller for permanent magnet brushless DC motor (PMBLDCM) drive. PMBLDC motors are the latest choice of researchers, due to the high efficiency, silent operation, compact size, high...... reliability, and low maintenance requirements. The proposed Power Factor Controller topology improves power quality by improving performance of PMBLDCM drive, such as reduction of AC main current harmonics, near unity power factor. PFC converter forces the drive to draw sinusoidal supply current in phase...... with supply voltage. It uses a boost converter to obtain unity power factor with improved performance. The system includes a speed controller for PMBLDC drive and a voltage controller for boost converter.. The voltage or speed controllers can be realized using proportional integral (PI) controller...

  2. Emergence of resistance and resistance management in field populations of tropical Culex quinquefasciatus to the microbial control agent Bacillus sphaericus.

    Science.gov (United States)

    Mulla, Mir S; Thavara, Usavadee; Tawatsin, Apiwat; Chomposri, Jakkrawarn; Su, Tianyun

    2003-03-01

    In recent years, highly potent mosquitocidal strains of the microbial agent Bacillus sphaericus (Bsph) have been isolated and developed for the control of mosquito larvae around the world. Laboratory selection experiments with the most active strains and their use in large-scale operational mosquito control programs resulted in the emergence of resistance in larvae of the Culex pipiens complex. This generated great concern among vector control agencies around the world, who feared reduced efficacy of this highly active larvicidal agent. To address this issue, the current studies were started to find practical strategies for controlling resistant mosquitoes and more importantly to develop resistance management strategies that would prevent or delay development of resistance. We initiated field studies in 3 low-income communities in Nonthaburi Province, Thailand. In 1 of the communities, larvae of Culex quinquefasciatus that were highly resistant (>125,000-fold) to Bsph strain 2362 were successfully controlled with applications of Bacillus thuringiensis var. israelensis (Bti) alone or in combination with Bsph. To prevent or delay resistance to Bsph, 2 other sites were selected, 1 treated with Bsph 2362 alone and the other treated with a mixture of Bsph 2362 and Bti. Mosquitoes treated with Bsph 2362 alone showed some resistance by the 9th treatment and almost complete failure of control occurred by the 17th treatment. After 9 treatments with the mixture over a 9-month period at another site, no noticeable change in susceptibility to Bsph was detected. During this period, the site treated with Bsph alone required 19 treatments, whereas the site treated with mixtures took only 9 treatments because of slower resurgence of larvae at the site treated with the mixture than at the site treated with Bsph alone. This is the 1st field evidence for delay or prevention of resistance to microbial agents in larval Cx. quinquefasciatus by using mixtures of Bti and Bsph. Further

  3. Rates of microbial sulfate reduction control the sizes of biogenic iron sulfide aggregates

    Science.gov (United States)

    Jin, Q.

    2005-12-01

    Sulfide minerals occur widely in freshwater and marine sediments as byproducts of microbial sulfate reduction and as end products of heavy metal bioremediation. They form when metals in the environments combine with sulfide produced from the metabolism of sulfate reducing bacteria. We used chemostat bioreactors to study sizes and crystal structures of iron sulfide (FeS) minerals produced by Desulfovibrio vulgaris, D. desulfuricans strain G20, and subspecies desulfuricans. FeS nanoparticles and their aggregates are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and dynamic light scattering (DLS). FeS nanoparticles produced by sulfate reducing bacteria are extremely small, usually less than around 10 nm in diameter. Nanoparticles do not occur as individual nanoparticles, but as aggregates. The sizes of FeS aggregates are affected by sulfate reduction rates, Fe(II) concentration, pH, ionic strength, organic matter concentration, bacterial species, etc. Aggregate size ranges from about 500 nm at very large sulfate reduction rates to about 1,500 nm at very small rates. Variations in Fe(II) concentration also lead to a difference up to 500 nm in FeS aggregate size. Different bacterial species produce nanoparticle aggregates of different sizes under similar growth conditions. For example, D. vulgaris produces FeS aggregates with sizes 500 nm smaller than those by strain G20. The inverse relationship between FeS aggregate sizes and sulfate reduction rates is important in evaluating metal bioremediation strategies. Previous approaches have focused on stimulating microbial activities in natural environments. However, our experimental results suggest that increasing metabolic rates may decrease the aggregate size, increasing the mobility of colloidal aggregates. Therefore, the balance between microbial activities and sizes of biogenic aggregates may be an important consideration in the design and

  4. Resveratrol treatment controls microbial flora, prolongs shelf life, and preserves nutritional quality of fruit.

    Science.gov (United States)

    Jiménez, Jorge Bernardo; Orea, José María; Montero, Carlos; Ureña, Angel González; Navas, Elena; Slowing, Karla; Gómez-Serranillos, María Pilar; Carretero, Emilia; De Martinis, Domenico

    2005-03-09

    Resveratrol is known as a grapevine secondary metabolite with fungicide activity. Its exogenous application on harvested grapes resulted in the reduction of microbial flora growth, and consequently, prolonged shelf life, without affecting the nutritional quality of the fruit. Resveratrol treatment also resulted in being effective on fruit that normally does not accumulate such metabolites as, for example, tomatoes, apples, avocado pears, and peppers. As a result, all treated fruits maintained their post-harvest quality and health longer than the untreated ones. This study demonstrates the potential use of resveratrol as a natural pesticide to reduce post-harvest fungi development on a broad spectrum of fruit types.

  5. Abiogenic and Microbial Controls on Volatile Fatty Acids in Precambrian Crustal Fracture Waters

    Science.gov (United States)

    McDermott, J. M.; Heuer, V.; Tille, S.; Moran, J.; Slater, G.; Sutcliffe, C. N.; Glein, C. R.; Hinrichs, K. U.; Sherwood Lollar, B.

    2015-12-01

    Saline fracture waters within the Precambrian Shield rocks of Canada and South Africa have been sequestered underground over geologic timescales up to 1.1-1.8 Ga [1, 2]. These fluids are rich in H2 derived from radiolysis and hydration of mafic and ultramafic rocks [1, 2, 3] and host a low-biomass, low-diversity microbial ecosystem at some sites [2]. The abiogenic or biogenic nature of geochemical processes has important implications for bioavailable carbon sources and the role played by abiotic organic synthesis in sustaining a chemosynthetic deep biosphere. Volatile fatty acids (VFAs) are simple carboxylic acids that may support microbial communities in such environments, such as those found in terrestrial [4] and deep-sea [5] hot springs. We present abundance and δ13C analysis for VFAs in a spectrum of Canadian Shield fluids characterized by varying dissolved H2, CH4, and C2+ n-alkane compositions. Isotope mass balance indicates that microbially mediated fermentation of carbon-rich graphitic sulfides may produce the elevated levels of acetate (39-273 μM) found in Birchtree and Thompson mine. In contrast, thermodynamic considerations and isotopic signatures of the notably higher acetate (1.2-1.9 mM), as well as formate and propionate abundances (371-816 μM and 20-38 μM, respectively) found at Kidd Creek mine suggest a role for abiogenic production via reduction of dissolved inorganic carbon with H2 for formate, and oxidation of C2+ n-alkanes for acetate and propionate, along with possible microbial cycling. VFAs comprise the bulk of dissolved and total organic carbon in the mines surveyed, and as such represent a potential key substrate for life. [1] Holland et al. (2013) Nature 497: 367-360. [2] Lin et al. (2006) Science 314: 479-482. [3] Sherwood Lollar et al. (2014) Nature 516: 379-382. [4] Windman et al. (2007) Astrobiology 7(6): 873-890. [5] Lang et al. (2010) Geochim. Cosmochim. Acta 92: 82-99.

  6. Host-derived, pore-forming toxin-like protein and trefoil factor complex protects the host against microbial infection.

    Science.gov (United States)

    Xiang, Yang; Yan, Chao; Guo, Xiaolong; Zhou, Kaifeng; Li, Sheng'an; Gao, Qian; Wang, Xuan; Zhao, Feng; Liu, Jie; Lee, Wen-Hui; Zhang, Yun

    2014-05-06

    Aerolysins are virulence factors belonging to the bacterial β-pore-forming toxin superfamily. Surprisingly, numerous aerolysin-like proteins exist in vertebrates, but their biological functions are unknown. βγ-CAT, a complex of an aerolysin-like protein subunit (two βγ-crystallin domains followed by an aerolysin pore-forming domain) and two trefoil factor subunits, has been identified in frogs (Bombina maxima) skin secretions. Here, we report the rich expression of this protein, in the frog blood and immune-related tissues, and the induction of its presence in peritoneal lavage by bacterial challenge. This phenomena raises the possibility of its involvement in antimicrobial infection. When βγ-CAT was administrated in a peritoneal infection model, it greatly accelerated bacterial clearance and increased the survival rate of both frogs and mice. Meanwhile, accelerated Interleukin-1β release and enhanced local leukocyte recruitments were determined, which may partially explain the robust and effective antimicrobial responses observed. The release of interleukin-1β was potently triggered by βγ-CAT from the frog peritoneal cells and murine macrophages in vitro. βγ-CAT was rapidly endocytosed and translocated to lysosomes, where it formed high molecular mass SDS-stable oligomers (>170 kDa). Lysosomal destabilization and cathepsin B release were detected, which may explain the activation of caspase-1 inflammasome and subsequent interleukin-1β maturation and release. To our knowledge, these results provide the first functional evidence of the ability of a host-derived aerolysin-like protein to counter microbial infection by eliciting rapid and effective host innate immune responses. The findings will also largely help to elucidate the possible involvement and action mechanisms of aerolysin-like proteins and/or trefoil factors widely existing in vertebrates in the host defense against pathogens.

  7. Temperature Dependence of Factors Controlling Isoprene Emissions

    Science.gov (United States)

    Duncan, Bryan N.; Yoshida, Yasuko; Damon, Megan R.; Douglass, Anne R.; Witte, Jacquelyn C.

    2009-01-01

    We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.

  8. Anti - microbial resistance stratified by risk factor among Escherichia coli strains isolated from the urinary tract at a rural clinic in Central India

    Directory of Open Access Journals (Sweden)

    Chatterjee B

    2009-01-01

    Full Text Available Background: The failure of empirical therapy is frequently observed, even in community-acquired urinary tract infections. We, therefore, conducted a prospective, clinic-based study in 2004-2005 to document anti-microbial resistance rates and correlate them with possible risk factors to assist empirical decision-making. Materials and Methods: Symptomatic patients with pyuria underwent urine culture. Isolates were identified using standard methods and anti-microbial resistance was determined by disk-diffusion. Ultrasonography was used to detect complicating factors. Patients were stratified by the presence of complicating factors and history of invasive procedures for comparison of resistance rates. Statistical Method Used: Chi-square or Fisher exact tests, as appropriate. Results: There were 156 E. coli isolates, of which 105 were community-acquired. Twenty-three community-acquired isolates were from patients with complicating factors while 82 were from patients without any. Fifty-one isolates were from patients who had recently undergone invasive procedures on the urinary tract. Thirty-two community-acquired isolates from reproductive-age women without apparent complicating factors had resistance rates of 50% or above against tetracyclines, Co-trimoxazole, aminopenicillins, Nalidixic acid, Ciprofloxacin and 1 st generation cephalosporins. Resistance rates were significantly higher among isolates from patients subjected to invasive procedures, except against Co-trimoxazole, tetracyclines and Amikacin. Conclusion: High rates of anti-microbial resistance in community-acquired uropathogens have made antimicrobial sensitivity testing necessary even in a rural, primary-care setting.

  9. DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

    Energy Technology Data Exchange (ETDEWEB)

    Kristine L. Lowe; Bill W. Bogan; Wendy R. Sullivan; Kristine Mila H. Cruz; Brigid M. Lamb; John J. Kilbane II

    2004-07-30

    The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Previous testing indicated that the growth, and the metal corrosion caused by pure cultures of sulfate reducing bacteria were inhibited by hexane extracts of some pepper plants. This quarter tests were performed with mixed bacterial cultures obtained from natural gas pipelines. Treatment with the pepper extracts affected the growth and metabolic activity of the microbial consortia. Specifically, the growth and metabolism of sulfate reducing bacteria was inhibited. The demonstration that pepper extracts can inhibit the growth and metabolism of sulfate reducing bacteria in mixed cultures is a significant observation validating a key hypothesis of the project. Future tests to determine the effects of pepper extracts on mature/established biofilms will be performed next.

  10. Antimicrobial peptides from marine invertebrates as a new frontier for microbial infection control.

    Science.gov (United States)

    Otero-González, Anselmo Jesus; Magalhães, Beatriz Simas; Garcia-Villarino, Monica; López-Abarrategui, Carlos; Sousa, Daniel Amaro; Dias, Simoni Campos; Franco, Octávio Luiz

    2010-05-01

    Antimicrobial peptides are widely expressed in organisms and have been linked to innate and acquired immunities in vertebrates. These compounds are constitutively expressed and rapidly induced at different cellular levels to interact directly with infectious agents and/or modulate immunoreactions involved in defense against pathogenic microorganisms. In invertebrates, antimicrobial peptides represent the major humoral defense system against infection, showing a diverse spectrum of action mechanisms, most of them related to plasma membrane disturbance and lethal alteration of microbial integrity. Marine invertebrates are widespread, extremely diverse, and constantly under an enormous microbial challenge from the ocean environment, itself altered by anthropic influences derived from industrialization and transportation. Consequently, this study reexamines the peptides isolated over the past 2 decades from different origins, bringing phyla not previously reviewed up to date. Moreover, a promising novel use of antimicrobial peptides as effective drugs in human and veterinary medicine could be based on their unusual properties and synergic counterparts as immune response humoral effectors, in addition to their direct microbicidal activity. This has been seen in many other marine proteins that are sufficiently immunogenic to humans, not necessarily in terms of antibody generation but as inflammation promoters and recruitment agents or immune enhancers.

  11. Effects of Different Control Measures on Cucumber Yield, Quality and Soil Microbial Diversity Under Green house Cultivation

    Directory of Open Access Journals (Sweden)

    LI Xin

    2014-08-01

    Full Text Available In order to research the effects of different control measures on soil microbial diversity by Biolog, the greenhouse soils of cucumber cultivated in Shouguang City, Shandong Prorince were collected and the relationship between the soils and yield and quality of cucumber was investigated. The results showed that, the average well color development(AWCDof returning straw to field(RSwas the highest and that of no fertilizer(CKwas the lowest. The activity of microbe was vigorous at the time of cultivation of 72 h and AWCD of treatments ranged from 0.494 to 0.881. AWCD of RS was 1.3 times than that of conventional fertilization(CFand the difference reached significant level at the moment. However, AWCD of drip irrigation(DIwas lower slightly than that of CF. Soil microbial diversity changed in different treatments. CF had the lowest Shannon index(Hand Substrate evenness(E, but these two indices increased significantly through the application of RS and DI. Principal component analysis showed that carbon utilization by soil microbial communities also changed in different treatments. RS concentrated in the positive direction of the first principal component and the score coefficients ranged from 4.91 to 5.50. Conversely, others concentrated in the negative direction and the score coefficients ranged from-3.26 to-0.18. Compared with CF, cucumber yield and quality of RS and DI treatments had no significant changes. Simpson’s dominance(Dsand Substrate richness(Swere positively correlated with cu-cumber yield, Vc and soluble sugar content. Comprehensive consideration, RS was more helpful to improve the soil micro-ecological envrion-ment than DI. Therefore, future research of RS is necessary for sustainable development of installation agriculture.

  12. Characterization and control of the microbial community affiliated with copper or aluminum heat exchangers of HVAC systems.

    Science.gov (United States)

    Schmidt, Michael G; Attaway, Hubert H; Terzieva, Silva; Marshall, Anna; Steed, Lisa L; Salzberg, Deborah; Hamoodi, Hameed A; Khan, Jamil A; Feigley, Charles E; Michels, Harold T

    2012-08-01

    Microbial growth in heating ventilation and air-conditioning (HVAC) systems with the subsequent contamination of indoor air is of increasing concern. Microbes and the subsequent biofilms grow easily within heat exchangers. A comparative study where heat exchangers fabricated from antimicrobial copper were evaluated for their ability to limit microbial growth was conducted using a full-scale HVAC system under conditions of normal flow rates using single-pass outside air. Resident bacterial and fungal populations were quantitatively assessed by removing triplicate sets of coupons from each exchanger commencing the fourth week after their installation for the next 30 weeks. The intrinsic biofilm associated with each coupon was extracted and characterized using selective and differential media. The predominant organisms isolated from aluminum exchangers were species of Methylobacterium of which at least three colony morphologies and 11 distinct PFGE patterns we found; of the few bacteria isolated from the copper exchangers, the majority were species of Bacillus. The concentrations and type of bacteria recovered from the control, aluminum, exchangers were found to be dependent on the type of plating media used and were 11,411-47,257 CFU cm(-2) per coupon surface. The concentration of fungi was found to average 378 CFU cm(-2). Significantly lower concentrations of bacteria, 3 CFU cm(-2), and fungi, 1 CFU cm(-2), were recovered from copper exchangers regardless of the plating media used. Commonly used aluminum heat exchangers developed stable, mixed, bacterial/fungal biofilms in excess of 47,000 organisms per cm(2) within 4 weeks of operation, whereas the antimicrobial properties of metallic copper were able to limit the microbial load affiliated with the copper heat exchangers to levels 99.97 % lower during the same time period.

  13. Controllable biosynthesis of high-purity lead-sulfide (PbS) nanocrystals by regulating the concentration of polyethylene glycol in microbial system.

    Science.gov (United States)

    Yue, Lei; Wang, Jia; Zhang, Yongtao; Qi, Shiyue; Xin, Baoping

    2016-12-01

    We demonstrated a simple biological method to explore the controllable synthesize of high-purity PbS nanocrystals by regulating the concentration of polyethylene glycol in microbial system. The biogenic H2S produced via the reduction of sulfate precipitated Pb(2+) ions as sulfide extracellularly, and the optimal removal rate of Pb(2+) ions is up to 96.7 % in 2 weeks. The characterization results showed that PbS nanocuboids with a particle size 50 × 50 × 100 nm obtained from Case A with 4 mM polyethylene glycol as a dispersant, and can completely degrade methylene blue from solution within 20 h; PbS nanosheets with a thickness size ca. 10 nm attained from Case B with 12 mM polyethylene glycol, and it can degrade 61.6 % dye within 24 h; PbS nanoparticles with a uniform diameter of ca. 60 nm formed from Case C with 20 mM polyethylene glycol, only degrade 14.1 % dye within 24 h. It is interesting that the factor affecting their catalytic activities is not the specific surface area, but the number of [200] crystal plane. This work not only displayed a simple synthetic method to control the morphology of PbS nanocrystals in microbial system, but also provided an economic and environmentally friendly approach for resourceful treatment and efficient bioremediation of wastewater-containing heavy metal.

  14. The role of host and microbial factors in the pathogenesis of pneumococcal bacteraemia arising from a single bacterial cell bottleneck.

    Directory of Open Access Journals (Sweden)

    Alice Gerlini

    2014-03-01

    Full Text Available The pathogenesis of bacteraemia after challenge with one million pneumococci of three isogenic variants was investigated. Sequential analyses of blood samples indicated that most episodes of bacteraemia were monoclonal events providing compelling evidence for a single bacterial cell bottleneck at the origin of invasive disease. With respect to host determinants, results identified novel properties of splenic macrophages and a role for neutrophils in early clearance of pneumococci. Concerning microbial factors, whole genome sequencing provided genetic evidence for the clonal origin of the bacteraemia and identified SNPs in distinct sub-units of F0/F1 ATPase in the majority of the ex vivo isolates. When compared to parental organisms of the inoculum, ex-vivo pneumococci with mutant alleles of the F0/F1 ATPase had acquired the capacity to grow at low pH at the cost of the capacity to grow at high pH. Although founded by a single cell, the genotypes of pneumococci in septicaemic mice indicate strong selective pressure for fitness, emphasising the within-host complexity of the pathogenesis of invasive disease.

  15. Risk factors for caries - control and prevention

    Directory of Open Access Journals (Sweden)

    Melida Hasanagić

    2008-08-01

    Full Text Available Objectives. To investigate a prevalence of caries, filled permanentand extracted permanent teeth, as well as caries risk factors inschool children aged 7, 9 and 11.Methods. The survey included 800 children (296 children aged7; 254 children aged 9 and 250 children aged 11 from the MostarMunicipality, 400 of them living in both rural and urban areas.A dental mirror and standard light of dental chair were used forexamination. The DMF index (Dental Caries, Missing Teeth andFilled Teeth was determined, as well as failure in keeping teethhygiene, sugar intake with food, and incidence of oral cavity infection.Results. The dental state of permanent teeth in children aged 7and 9 has shown significant difference between the children fromrural and urban areas (p < 0,001. Out of 2,698 and 2,790 permanentteeth in children aged 11 from rural and urban areas, 1,086(40,25 % and 884 (31.68 % had caries, respectively (p < 0.01.The difference between these groups of children has been foundin relation to the index of oral hygiene too (p < 0.05.Conclusion. An identification of risk groups for getting caries wasvery important and could help health and social structures to maintaintheir programs in order to improve oral health.

  16. Quality-Control Analytical Methods: Microbial-Testing Aspects of USP Chapter 797 for Compounded Sterile Preparations.

    Science.gov (United States)

    Kupiec, Thomas C

    2005-01-01

    The standards set forth by the United States Pharmacopeia (USP) Chapter 797 have now been in effect since January 1 or 2004. As the first practice standards of sterile pharmacy compounding in US history, they have "attracted both respect and criticism" because they have also been cited as a practice expectation by the Joint Commission on Accreditation of Healthcare Organizations. USP 797 expands the scope of facilities governed by the regulatinos and defines the practices covered, emphasizing the importance of environmental quality and control, verification of accuracy and sterility, training and evaluation, quality control after preparations leave the pharmacy, patient monitoring and adverse events reporting. The purpose of this article is to help the reader understand the criteria set forth by USP Chapter 797 regarding finished-product testing, including criteria for the microbial-testing aspects of sterility testing (USP Chapter 71) and endotoxin (pyrogen) testing (USP Chapter 85).

  17. [Dynamics of microbial biomass P and its affecting factors in a long-term fertilized black soil].

    Science.gov (United States)

    Li, Dongpo; Wu, Zhijie; Chen, Lijun; Zhu, Ping; Ren, Jun; Liang, Chenghua; Peng, Chang; Gao, Hongjun

    2004-10-01

    This paper studied the microbial biomass P in a long-term fertilized black soil. The soil was fertilized by farmyard manure (M2, M4) and chemical fertilizer (NPK), and the dynamics of soil microbial biomass P was monitored during crop growth season. The results showed that the microbial biomass P in different treatments was 8.75-47.68 mg x kg(-1) (M4), 3.02-37.16 mg x kg(-1) (M2), 1.59-10.62 mg x kg(-1) (NPK), and 0.76-6.74 mg x kg(-1) (CK). The microbial biomass P in M4 and M2 was the highest at reproductive growth stage, and that in NPK and CK was the highest at early growth stage. The significant difference of soil microbial biomass P induced by different amounts and types of fertilizer application was not varied with the period and stage of plant growth. In all treatments, no significant correlation was found between the dynamics of soil microbial biomass P and the soil biological, physical and chemical properties in plant growth period. Soil microbial biomass P had a very significant positive correlation with soil biological, physical and chemical properties (expect K), and a significant positive correlation with the N, P and K contents of plants and soil water content.

  18. Control of hydrogen sulfide production in oil fields by managing microbial communities through nitrate or nitrite addition

    Science.gov (United States)

    Hubert, Casey R. J.

    Nitrate or nitrite injection into oil reservoirs during water flooding has the potential to control biological souring, the production of hydrogen sulfide (H2S) by sulfate-reducing bacteria (SRB). Souring control is essential because sulfide is toxic, sulfide precipitates can plug reservoir formations, souring lowers crude oil value, and SRB induce corrosion. Nitrate and nitrite can stimulate heterotrophic nitrate- or nitrite-reducing bacteria (hNRB) and nitrate- or nitrite-reducing, sulfide oxidizing bacteria (NRSOB). Nitrite also inhibits SRB activity by blocking the sulfate reduction pathway. Continuous up-flow packed-bed bioreactors were inoculated with produced water from the Coleville oil field to establish sulfide-producing biofilms similar to those found in sour reservoirs. Nitrate or nitrite addition to bioreactors indicated that the dose required for hNRB or NR-SOB to control souring depended on the concentration of oil organics. Either mechanism mediates the net removal of oil organics (lactate) with nitrate or nitrite, with lower doses of nitrate required due to its greater oxidative power. Microbial community analysis by reverse sample genome probing (RSGP) revealed that NR-SOB mediated sulfide removal at low nitrate or nitrite concentrations when lactate was still available to SRB and the redox potential was low. At high nitrate doses hNRB oxidized lactate directly, produced nitrite and maintained a high redox potential, thus excluding SRB activity. Facultatively chemolithotrophic Campylobacter sp. strains were isolated from the bioreactors and incorporated into RSGP analyses, revealing their dominance in both NR-SOB- and hNRB-containing communities. The metabolic flexibility of these strains may confer a competitive advantage over obligate chemolithotrophs like Thiomicrospira sp. strain CVO or hNRB that do not have NR-SOB activity like newly isolated Thauera sp. and Rhodobacter sp. strains. A single high dose of nitrite resulted in immediate

  19. Temperature and solids retention time control microbial population dynamics and volatile fatty acid production in replicated anaerobic digesters

    Science.gov (United States)

    Vanwonterghem, Inka; Jensen, Paul D.; Rabaey, Korneel; Tyson, Gene W.

    2015-02-01

    Anaerobic digestion is a widely used technology for waste stabilization and generation of biogas, and has recently emerged as a potentially important process for the production of high value volatile fatty acids (VFAs) and alcohols. Here, three reactors were seeded with inoculum from a stably performing methanogenic digester, and selective operating conditions (37°C and 55°C 12 day and 4 day solids retention time) were applied to restrict methanogenesis while maintaining hydrolysis and fermentation. Replicated experiments performed at each set of operating conditions led to reproducible VFA production profiles which could be correlated with specific changes in microbial community composition. The mesophilic reactor at short solids retention time showed accumulation of propionate and acetate (42 +/- 2% and 15 +/- 6% of CODhydrolyzed, respectively), and dominance of Fibrobacter and Bacteroidales. Acetate accumulation (>50% of CODhydrolyzed) was also observed in the thermophilic reactors, which were dominated by Clostridium. Under all tested conditions, there was a shift from acetoclastic to hydrogenotrophic methanogenesis, and a reduction in methane production by >50% of CODhydrolyzed. Our results demonstrate that shortening the SRT and increasing the temperature are effective strategies for driving microbial communities towards controlled production of high levels of specific volatile fatty acids.

  20. Chalcopyrite leaching: The rate controlling factors

    Science.gov (United States)

    Li, J.; Kawashima, N.; Kaplun, K.; Absolon, V. J.; Gerson, A. R.

    2010-05-01

    The processes that determine the rate of chalcopyrite leaching are central to understanding how chalcopyrite (CuFeS 2) behaves under the environmentally adverse conditions of acid rock drainage. To this end the effect of the acid anion on chalcopyrite leach rates using a variety of acidic media (H 2SO 4, HClO 4, HCl and H 2SO 4 with 0.25 M NaCl) under carefully controlled solution conditions (pH 1 and 2, Eh 750 mV (SHE) and 75 °C) has been examined. These conditions have been chosen to enable sufficient leach rates for accurate experimental determination and to compare to the previous mechanistic analysis carried out by Harmer et al. (2006). Extensive surface analysis of leach residues demonstrated that variations in the surface speciation could not be responsible for the observed variations in leach rate. The rate of Cu release, however, was found to be first order with respect to Fe 3+ activity and inversely proportional with respect to H + activity to the power of 0.7: {1}/{S}{dC}/{dt}=(2.0±0.2){a}/{aH0.7} where S is the relative surface area, C is concentration of Cu in the solution (M), t is the time (h), 2.0 is the rate constant (M 0.7 h -1) and a and a are Fe 3+ and H + activities, respectively (M). The rate model was further validated against additional leaches carried out in H 2SO 4 media with the initial addition of Fe 3+ (8 mM as Fe 2(SO 4) 3) at 75 °C under various pH and Eh regimes. The only condition under which this rate model was found not to hold was at simultaneously low a and high a, that is at pH 1 and a<5×10-5M, where the concentration of dissolved O 2 may be leach rate determining.

  1. Soft electron (low energy electron) processing of foods for microbial control

    Energy Technology Data Exchange (ETDEWEB)

    Todoriki, Setsuko E-mail: setsuko@nfri.affrc.go.jp; Kikuchi, Olivia Kimiko; Nakaoka, Motoko; Miike, Mika; Hayashi, Toru

    2002-03-01

    'Soft-electron' is a new term we have created referring to electrons with energies of 300 kV or lower. Homogenous irradiation of surfaces with soft electrons can decontaminate dry food ingredients such as gains, pulses, spices, dehydrated vegetables and tealeaves without detrimental effects. Treatment of soybeans with electrons of acceleration voltages at 170 kV reduced their microbial count to an undetectable level. Pre-treatment of soybeans with soft electrons enabled the extension of soymilk without sterilization process at a high temperature (120 deg. C). The gelatinized property of soymilk from soft electron-treated beans was better than that of high-temperature sterilized soymilks. These results indicate that soft-electron sterilization improved the quality of soybeans for the processing of soymilk and Tofu(soymilk curd)

  2. Geomicrobiology of sublacustrine thermal vents in Yellowstone Lake: geochemical controls on microbial community structure and function.

    Science.gov (United States)

    Inskeep, William P; Jay, Zackary J; Macur, Richard E; Clingenpeel, Scott; Tenney, Aaron; Lovalvo, David; Beam, Jacob P; Kozubal, Mark A; Shanks, W C; Morgan, Lisa A; Kan, Jinjun; Gorby, Yuri; Yooseph, Shibu; Nealson, Kenneth

    2015-01-01

    Yellowstone Lake (Yellowstone National Park, WY, USA) is a large high-altitude (2200 m), fresh-water lake, which straddles an extensive caldera and is the center of significant geothermal activity. The primary goal of this interdisciplinary study was to evaluate the microbial populations inhabiting thermal vent communities in Yellowstone Lake using 16S rRNA gene and random metagenome sequencing, and to determine how geochemical attributes of vent waters influence the distribution of specific microorganisms and their metabolic potential. Thermal vent waters and associated microbial biomass were sampled during two field seasons (2007-2008) using a remotely operated vehicle (ROV). Sublacustrine thermal vent waters (circa 50-90°C) contained elevated concentrations of numerous constituents associated with geothermal activity including dissolved hydrogen, sulfide, methane and carbon dioxide. Microorganisms associated with sulfur-rich filamentous "streamer" communities of Inflated Plain and West Thumb (pH range 5-6) were dominated by bacteria from the Aquificales, but also contained thermophilic archaea from the Crenarchaeota and Euryarchaeota. Novel groups of methanogens and members of the Korarchaeota were observed in vents from West Thumb and Elliot's Crater (pH 5-6). Conversely, metagenome sequence from Mary Bay vent sediments did not yield large assemblies, and contained diverse thermophilic and nonthermophilic bacterial relatives. Analysis of functional genes associated with the major vent populations indicated a direct linkage to high concentrations of carbon dioxide, reduced sulfur (sulfide and/or elemental S), hydrogen and methane in the deep thermal ecosystems. Our observations show that sublacustrine thermal vents in Yellowstone Lake support novel thermophilic communities, which contain microorganisms with functional attributes not found to date in terrestrial geothermal systems of YNP.

  3. Geomicrobiology of sublacustrine thermal vents in Yellowstone Lake: Geochemical controls on microbial community structure and function

    Directory of Open Access Journals (Sweden)

    William P. Inskeep

    2015-10-01

    Full Text Available Yellowstone Lake (Yellowstone National Park, WY, USA is a large high-altitude (2200 m, fresh-water lake, which straddles an extensive caldera and is the center of significant geothermal activity. The primary goal of this interdisciplinary study was to evaluate the microbial populations inhabiting thermal vent communities in Yellowstone Lake (Yellowstone Lake using 16S rRNA gene and random metagenome sequencing, and to determine how geochemical attributes of vent waters influence the distribution of specific microorganisms and their metabolic potential. Thermal vent waters and associated microbial biomass were sampled during two field seasons (2007 - 2008 using a remotely operated vehicle (ROV. Sublacustrine thermal vent waters (circa 50 - 90 oC contained elevated concentrations of numerous constituents associated with geothermal activity including dissolved hydrogen, sulfide, methane and carbon dioxide. Microorganisms associated with sulfur-rich filamentous ‘streamer’ communities of Inflated Plain and West Thumb (pH range 5 - 6 were dominated by bacteria from the Aquificales, but also contained thermophilic archaea from the Crenarchaeota and Euryarchaeota. Novel groups of methanogens and members of the Korarchaeota were observed in vents from West Thumb and Elliot’s Crater (pH 5 - 6. Conversely, metagenome sequence from Mary Bay vent sediments did not yield large assemblies, and contained diverse thermophilic and nonthermophilic bacterial relatives. Analysis of functional genes associated with the major vent populations indicated a direct linkage to high concentrations of carbon dioxide, reduced sulfur (sulfide and/or elemental S, hydrogen and methane in the deep thermal ecosystems. Our observations show that sublacustrine thermal vents in Yellowstone Lake support novel thermophilic communities, which contain microorganisms with functional attributes not found to date in terrestrial geothermal systems of YNP.

  4. MICROBIAL FLORA AND RISK FACTORS ASSOCIATED WITH CATHETER ASSOCIATED URINARY TRACT INFECTIONS

    Directory of Open Access Journals (Sweden)

    Ravi Prakash

    2015-05-01

    surveillance of infection is the most effective method to control the CA UTI s.

  5. [Dynamics of microbial biomass C in a black soil under long-term fertilization and related affecting factors].

    Science.gov (United States)

    Li, Dongpo; Wu, Zhijie; Chen, Lijun; Zhu, Ping; Ren, Jun; Peng, Chang; Liang, Chenghua

    2004-08-01

    The effect of long-term fertilization on the dynamics of microbial biomass C in a typical black soil of Northeastern China was studied in a field trail treated by different fertilizations. The results showed that the amount of soil microbial biomass C under different fertilizations varied significantly with growth stages. It was the highest in farmyard manure (M2 and M4) treatments, with a less seasonal fluctuation, second in NPK treatment, the peak at sowing period, and the lowest in CK, the peak at wax maturity stage. No significant correlation was found between the dynamic changes of soil microbial biomass C and soil biological, physical and chemical properties in all treatments, but the correlation of soil microbial biomass C with the contents of N, P and K in plants and that of crude protein in grain was significantly positive.

  6. Physical factors correlate to microbial community structure and nitrogen cycling gene abundance in a nitrate fed eutrophic lagoon

    OpenAIRE

    Matthew Paul Highton; Stéphanie Roosa; Josie Crawshaw; Marc Schallenberg; Sergio E. Morales

    2016-01-01

    Nitrogenous run-off from farmed pastures contributes to the eutrophication of Lake Ellesmere, a large shallow lagoon/lake on the east coast of New Zealand. Tributaries periodically deliver high loads of nitrate to the lake which likely affect microbial communities therein. We hypothesized that a nutrient gradient would form from the potential sources (tributaries) creating a disturbance resulting in changes in microbial community structure. To test this we first determined the existence of su...

  7. MACROPHAGE MIGRATION INHIBITORY FACTOR IN PATIENTS WITH PRETERM PARTURITION AND MICROBIAL INVASION OF THE AMNIOTIC CAVITY

    Science.gov (United States)

    Chaiworapongsa, Tinnakorn; Romero, Roberto; Espinoza, Jimmy; Kim, Yeon Mee; Edwin, Samuel; Bujold, Emmanuel; Gomez, Ricardo; Kuivaniemi, Helena

    2006-01-01

    OBJECTIVE Macrophage migration inhibitory factor (MIF) has emerged as an important mediator of septic shock. The administration of MIF increases lethality during endotoxemia, whereas neutralization of this cytokine prevents endotoxic shock and death associated with bacterial infection. The objective of this study was to determine whether there is a change in the amniotic fluid concentration of MIF in intra-amniotic infection and human parturition. STUDY DESIGN A cross-sectional study was conducted in women in the following categories: 1) midtrimester (n=84); 2) preterm labor and intact membranes who delivered at term (n=33), who delivered preterm (n=53), and preterm labor with intra-amniotic infection (n=23); 3) preterm premature rupture of membranes (PROM) with (n=25) and without intra-amniotic infection (n=26); and 4) term with intact membranes, in labor (n=52), and not in labor (n=31). MIF concentrations in amniotic fluid were determined using a sensitive and specific immunoassay. MIF concentrations in maternal plasma were also determined in patients with preterm labor and intact membranes. Immunohistochemistry was conducted in chorioamniotic membranes obtained from a different set of patients presenting with preterm labor with (n=18) and without (n=20) histologic chorioamnionitis. Quantitative RT-PCR was used to measure MIF mRNA expression in chorioamniotic membranes of patients with preterm labor with (n=13) and without (n=13) histologic chorioamnionitis. Parametric and non-parametric, receiver-operating characteristic (ROC) curve, survival analysis, and Cox regression model were used for analysis. RESULTS Immunoreactive MIF was detectable in 96% (313/327) of amniotic fluid samples. The concentration of amniotic fluid MIF at term was higher than that in the midtrimester (p=0.004). Intra-amniotic infection in women with preterm labor and preterm PROM was associated with a significant increase in median amniotic fluid MIF concentration (p0.05). There was no

  8. Italian multicenter study on infection hazards during dental practice: Control of environmental microbial contamination in public dental surgeries

    Science.gov (United States)

    Castiglia, Paolo; Liguori, Giorgio; Montagna, Maria Teresa; Napoli, Christian; Pasquarella, Cesira; Bergomi, Margherita; Fabiani, Leila; Monarca, Silvano; Petti, Stefano

    2008-01-01

    Background The present study assessed microbial contamination in Italian dental surgeries. Methods An evaluation of water, air and surface microbial contamination in 102 dental units was carried out in eight Italian cities. Results The findings showed water microbial contamination in all the dental surgeries; the proportion of water samples with microbial levels above those recommended decreased during working. With regard to Legionella spp., the proportion of positive samples was 33.3%. During work activity, the index of microbial air contamination (IMA) increased. The level of microbial accumulation on examined surfaces did not change over time. Conclusion These findings confirm that some Italian dental surgeries show high biocontamination, as in other European Countries, which highlights the risk of occupational exposure and the need to apply effective measures to reduce microbial loads. PMID:18644099

  9. The microbial temperature sensitivity to warming is controlled by thermal adaptation and is independent of C-quality across a pan-continental survey

    Science.gov (United States)

    Berglund, Eva; Rousk, Johannes

    2017-04-01

    Climate models predict that warming will result in an increased loss of soil organic matter (SOM). However, field experiments suggest that although warming results in an immediate increase in SOM turnover, the effect diminishes over time. Although the use and subsequent turnover of SOM is dominated by the soil microbial community, the underlying physiology underpinning warming responses are not considered in current climate models. It has been suggested that a reduction in the perceived quality of SOM to the microbial community, and changes in the microbial thermal adaptation, could be important feed-backs to soil warming. Thus, studies distinguishing between temperature relationships and how substrate quality influences microbial decomposition are a priority. We examined microbial communities and temperature sensitivities along a natural climate gradient including 56 independent samples from across Europe. The gradient included mean annual temperatures (MAT) from ca -4 to 18 ˚ C, along with wide spans of environmental factors known to influence microbial communities, such as pH (4.0 to 8.8), nutrients (C/N from 7 to 50), SOM (from 4 to 94%), and plant communities, etc. The extensive ranges of environmental conditions resulted in wide ranges of substrate quality, indexed as microbial respiration per unit SOM, from 5-150 μg CO2g-1 SOM g-1 h-1. We hypothesised microbial communities to (1) be adapted to the temperature of their climate, leading to warm adapted bacterial communities that were more temperature sensitive (higher Q10s) at higher MAT; (2) have temperature sensitivities affected by the quality of SOM, with higher Q10s for lower quality SOM. To determine the microbial use of SOM and its dependence on temperature, we characterized microbial temperature dependences of bacterial growth (leu inc), fungal growth (ac-in-erg) and soil respiration in all 56 sites. Temperature dependences were determined using brief (ca. 1-2 h at 25˚ C) laboratory incubation

  10. Evaluation of two spike-and-recovery controls for assessment of extraction efficiency in microbial source tracking studies

    Science.gov (United States)

    Stoeckel, D.M.; Stelzer, E.A.; Dick, L.K.

    2009-01-01

    Quantitative PCR (qPCR), applied to complex environmental samples such as water, wastewater, and feces, is susceptible to methodological and sample related biases. In this study, we evaluated two exogenous DNA spike-and-recovery controls as proxies for recovery efficiency of Bacteroidales 16S rDNA gene sequences (AllBac and qHF183) that are used for microbial source tracking (MST) in river water. Two controls-(1) the plant pathogen Pantoea stewartii, carrying the chromosomal target gene cpsD, and (2) Escherichia coli, carrying the plasmid-borne target gene DsRed2-were added to raw water samples immediately prior to concentration and DNA extraction for qPCR. When applied to samples processed in replicate, recovery of each control was positively correlated with the observed concentration of each MST marker. Adjustment of MST marker concentrations according to recovery efficiency reduced variability in replicate analyses when consistent processing and extraction methodologies were applied. Although the effects of this procedure on accuracy could not be tested due to uncertainties in control DNA concentrations, the observed reduction in variability should improve the strength of statistical comparisons. These findings suggest that either of the tested spike-and-recovery controls can be useful to measure efficiency of extraction and recovery in routine laboratory processing. ?? 2009 Elsevier Ltd.

  11. Revisiting factors controlling methane emissions from high-Arctic tundra

    DEFF Research Database (Denmark)

    Mastepanov, M.; Sigsgaard, Charlotte; Tagesson, Håkan Torbern;

    2013-01-01

    controlling methane emission, i.e. temperature and water table position. Late in the growing season CH4 emissions were found to be very similar between the study years (except the extremely dry 2010) despite large differences in climatic factors (temperature and water table). Late-season bursts of CH4...... short-term control factors (temperature and water table). Our findings suggest the importance of multiyear studies with a continued focus on shoulder seasons in Arctic ecosystems....

  12. Effect of additional of microbial growth factors combined with and without microbe preparate on growth performance of Etawah-cross goat

    Directory of Open Access Journals (Sweden)

    Amlius thalib

    2002-12-01

    Full Text Available Effect of microbial growth factors (FPM combined with and without microbe preparate (SM on growth of Etawah-crossgoat has been conducted for 14 weeks, including 2 weeks of adaptation period. Animals used were 24 male goats of Etawahcross (PE with a mean liveweight of 17.73 ± 1.80 kg. The animals were randomly distributed into 3 treatment groups. Eachgroup consisted of 8 animals. All animals were fed elephant grass (ad lib. + concentrate containing 16% crude protein (1.0% oflive weight as basal diet. The treatment groups were : I. Control (K; II. K + FPM; III. K + SM + FPM. Measurements recordedwere: feed consumption, average daily gain (ADG, dry matter digestibility (in vitro and in vivo DMDs, as well as rumenecosystem. All animals were placed in metabolism cages for 2 weeks for determination of in vivo DMD. The results showed thatFPM combined with and without SM improved the performance of both rumen ecosystem and host animals. Compared tocontrol, combination of FPM with SM increased the following parameters significantly (P<0.05: ADG (55 vs. 36 g; DMI (645vs. 609 g head-1 day-1; in vivo DMD (74 vs. 69%; FCR (12 vs. 17; in vitro DMD (49 vs. 46%; colony number of bacteria percell number of protozoa (3.09 x 104 vs. 1.12 x 104; VFA content (3.53 vs. 2.82 mg ml-1; NH3-N content (68 vs. 56 mg l-1; pH(6.78 vs. 6.65. Microbe preparate enhanced the effect of FPM on VFA content so that the combination of FPM and SM(treatment III significantly increased the VFA content as compared to the control (P<0.05.

  13. COMPLIANCE AS FACTORING BUSINESS RISK MANAGEMENT: CONTROL ASPECTS

    Directory of Open Access Journals (Sweden)

    V.K. Makarovych

    2016-03-01

    Full Text Available Indetermination of modern economy conditions and the lack of theoretical knowledge gained by domestic scientists about risk in factoring business actualize the research concerning the methodology and technique of factoring companies’ risk management. The article examines compliance which is the technology innovative for Ukrainian market of factoring risk management technologies. It is determined that the compliance is the risk management process directed to free will correspondence to state, international legislation as well as to the ethics standards accepted in the field of regulated legal relations and to the traditions of business circulation to sustain the necessary regulations and standards of market behaviour, and to consolidate the image of a factoring company. Compliance risks should be understood as the risks of missed profit or losses caused by the conflicts of interests and the discrepancy of employees’ actions to internal and external standard documents. The attention is paid to the control over the compliance. The author singles out 3 kinds of the compliance control such as institutional, operational and the compliance control over the observance of conducting business professional ethics regulations which are necessary for providing of efficient management of factoring business risks. The paper shows the organizing process of factoring business compliance control (by the development of internal standard documents, a compliance program, the foundation of compliance control subdivision, monitoring of the risks cause the choice, made by management entities of a factoring company, of the management methods of risks for their business. The development of new and improvement of existed forms of compliance control organizing process help satisfy users’ information needs and requests of the risk management factoring company department. The suggestions proposed create the grounds for the transformation and improvement of factoring

  14. Control of power sourced from a microbial fuel cell reduces its start-up time and increases bioelectrochemical activity.

    Science.gov (United States)

    Boghani, Hitesh C; Kim, Jung Rae; Dinsdale, Richard M; Guwy, Alan J; Premier, Giuliano C

    2013-07-01

    Microbial fuel cell (MFC) performance depends on the selective development of an electrogenic biofilm at an electrode. Controlled biofilm enrichment may reduce start-up time and improve subsequent power performance. The anode potential is known to affect start-up and subsequent performance in electrogenic bio-catalytic consortia. Control strategies varying electrical load through gradient based maximum power point tracking (MPPT) and transient poised anode potential followed by MPPT are compared to static ohmic loading. Three replicate H-type MFCs were used to investigate start-up strategies: (1) application of an MPPT algorithm preceded by poised-potential at the anode (+0.645 V vs Ag/AgCl); (2) MFC connected to MPPT-only; (3) static external load of 1 kΩ and 500 Ω. Active control showed a significant reduction in start-up time from 42 to 22 days, along with 3.5-fold increase in biocatalytic activity after start-up. Such active control may improve applicability by accelerating start-up and enhancing MFC power and bio-catalytic performance. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. DEVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

    Energy Technology Data Exchange (ETDEWEB)

    J. Robert Paterek; Gemma Husmillo

    2002-07-01

    The overall program objective is to develop and evaluate environmental benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is one or more environmental benign, a.k.a. ''green'' products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Capsicum sp. extracts and pure compounds were screened for their antimicrobial activity against MIC causing bacteria. Studies on the ability of these compounds to dissociate biofilm from the substratum were conducted using microtiter plate assays. Tests using laboratory scale pipeline simulators continued. Preliminary results showed that the natural extracts possess strong antimicrobial activity being comparable to or even better than the pure compounds tested against strains of sulfate reducers. Their minimum inhibitory concentrations had been determined. It was also found that they possess bactericidal properties at minimal concentrations. Biofilm dissociation activity as assessed by microtiter plate assays demonstrated varying degrees of differences between the treated and untreated group with the superior performance of the extracts over pure compounds. Such is an indication of the possible benefits that could be obtained from these natural products. Confirmatory experiments are underway.

  16. Improved performance of single-chamber microbial fuel cells through control of membrane deformation

    KAUST Repository

    Zhang, Xiaoyuan

    2010-03-01

    Cation (CEMs) and anion exchange membrane (AEMs) are commonly used in microbial fuel cells (MFCs) to enhance Coulombic efficiencies (CEs) by reducing thefluxof oxygen through the cathode to bacteriaonthe anode. AEMs typically work better than CEMs, but in initial experiments we observed the opposite using a membrane electrode assembly MFC. The reason was identified to be membrane deformation, which resulted in water and gas trapped between the membrane and cathode. To correct this, stainless steel mesh was used to press the membrane flat against the cathode. With the steel mesh, AEM performance increased to 46±4W/m3 in a single cathode MFC, and 98±14W/m3 in a double-cathode MFC. These power densities were higher than those using a CEM of 32±2W/m3 (single cathode) and 63±6W/m3 (double cathode). Higher pH gradients across the membrane and salt precipitation on the cathode were responsible for the reduced performance of the CEM compared to the AEM. CEs reached over 90% for both membranes at >2A/m2. These results demonstrate the importance of avoiding water accumulation in thin films between membranes and electrodes, and explain additional reasons for poorer performance of CEMs compared to AEMs. © 2009 Elsevier B.V.

  17. ATP monitoring technology for microbial growth control in potable water systems

    Science.gov (United States)

    Whalen, Patrick A.; Whalen, Philip J.; Cairns, James E.

    2006-05-01

    ATP (Adenosine Triphosphate) is the primary energy transfer molecule present in all living biological cells on Earth. ATP cannot be produced or maintained by anything but a living organism, and as such, its measurement is a direct indication of biological activity. The main advantage of ATP as a biological indicator is the speed of the analysis - from collecting the sample to obtaining the result, only minutes are required. The technology to measure ATP is already widely utilized to verify disinfection efficacy in the food industry and is also commonly applied in industrial water processes such as cooling water systems to monitor microbial growth and biocide applications. Research has indicated that ATP measurement technology can also play a key role in such important industries as potable water distribution and biological wastewater treatment. As will be detailed in this paper, LuminUltra Technologies has developed and applied ATP measurement technologies designed for any water type, and as such can provide a method to rapidly and accurately determine the level of biological activity in drinking water supplies. Because of its speed and specificity to biological activity, ATP measurement can play a key role in defending against failing drinking water quality, including those encountered during routine operation and also bioterrorism.

  18. Confirmatory Factor Analysis of the Work Locus of Control Scale

    Science.gov (United States)

    Oliver, Joseph E.; Jose, Paul E.; Brough, Paula

    2006-01-01

    Original formulations of the Work Locus of Control Scale (WLCS) proposed a unidimensional structure of this measure; however, more recently, evidence for a two-dimensional structure has been reported, with separate subscales for internal and external loci of control. The current study evaluates the one- and two-factor models with confirmatory…

  19. Human factors survey of advanced instrumentation and controls

    Energy Technology Data Exchange (ETDEWEB)

    Carter, R.J.

    1989-01-01

    A survey oriented towards identifying the human factors issues in regard to the use of advanced instrumentation and controls (I C) in the nuclear industry was conducted. A number of United States (US) and Canadian nuclear vendors and utilities were participants in the survey. Human factors items, subsumed under the categories of computer-generated displays (CGD), controls, organizational support, training, and related topics, were discussed. The survey found the industry to be concerned about the human factors issues related to the implementation of advanced I C. Fifteen potential human factors problems were identified. They include: the need for an advanced I C guideline equivalent to NUREG-0700; a role change in the control room from operator to supervisor; information overload; adequacy of existing training technology for advanced I C; and operator acceptance and trust. 11 refs., 1 tab.

  20. Soft Controls: Technical Basis and Human Factors Review Guidance

    Science.gov (United States)

    2000-03-01

    Controlling Office is (insert controlling DoD office). NUREG /CR-6635 BNL- NUREG -52565 Soft Controls: Technical Basis and Human Factors Review Guidance...DC 20555-0001 AVAILABILITY NOTICE Availability of Reference Materials Cited in NRC Publications NRC publications in the NUREG series, NRC regu...Technical Information Service Springfield, VA 22161 -0002 <http://www.ntis.gov> 1 -800-553-6847 or locally 703-605-6000 The NUREG series

  1. Aircraft Loss of Control Causal Factors and Mitigation Challenges

    Science.gov (United States)

    Jacobson, Steven R.

    2010-01-01

    Loss of control is the leading cause of jet fatalities worldwide. Aside from their frequency of occurrence, accidents resulting from loss of aircraft control seize the public s attention by yielding a large number of fatalities in a single event. In response to the rising threat to aviation safety, the NASA Aviation Safety Program has conducted a study of the loss of control problem. This study gathered four types of information pertaining to loss of control accidents: (1) statistical data; (2) individual accident reports that cite loss of control as a contributing factor; (3) previous meta-analyses of loss of control accidents; and (4) inputs solicited from aircraft manufacturers, air carriers, researchers, and other industry stakeholders. Using these information resources, the study team identified the causal factors that were cited in the greatest number of loss of control accidents, and which were emphasized most by industry stakeholders. This report describes the study approach, the key causal factors for aircraft loss of control, and recommended mitigation strategies to make near-term impacts, mid-term impacts, and Next Generation Air Transportation System impacts on the loss of control accident statistics

  2. Quantification and control of restrictive ecological factors in acidogenic de-sulfate bioreactor

    Institute of Scientific and Technical Information of China (English)

    王爱杰; 任南琪

    2002-01-01

    As an artificial microbial ecosystem, acidogenic de-sulfate bioreactor has high efficiency of sulfate removal. The restrictive ecological factors, including causing ecological factors, such as COD/SO42- ratio and sulfate loading rate (Ns), and following ecological factors, such as pH value, oxidation reduction potential (ORP) and alkalinity (ALK) have significant effect on the ability and stability of acidogenic de-sulfate bio-reactor. Continuous flow and batch test were carried out to investigate the quantification and control of COD/SO42- ratio, Ns, pH value, ORP and ALK in acidogenic de-sulfate bioreactor supplied with molasses wastewater as sole organic carbon source and sodium sulfate as electron donor. It was demonstrated that In order to maintain high sulfate removal rate (SRR) of 80% to 90%, the restrictive factors should meet all the requirement as follows: kCOD/ SO42- ratio≥2.0, Ns≤7.5 kg (m3·d)-1,pH=5.7~6.2,ORP=-320~-420 mV and ALK=1 500~2 000 mg/L.

  3. Mental depression as a risk factor for periodontal disease: A case-control study

    Directory of Open Access Journals (Sweden)

    Zareen Fatima

    2016-01-01

    Full Text Available Aim: Periodontal disease is an immune-inflammatory response of tooth supporting structures to microbial dental plaque. It is influenced by various factors such as poor oral hygiene, smoking, systemic diseases, and psychological factors such as stress. This case-control study was performed to consider mental depression as a risk factor for periodontal disease. Materials and Methods: A total of 170 subjects were selected. All the subjects were assessed for the presence of depression by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria and severity of depression was measured by Hamilton depression rating scale. For assessment of periodontal disease, clinical periodontal parameters oral hygiene index, gingival index, probing pocket depth (PPD, and clinical attachment level (CAL were recorded. Results: Univariate logistic regression analysis demonstrated that subjects with depression had significantly higher values of debris index, calculus index, gingival index, PPD, and CAL (P 6 months of illness were higher (P < 0.05. Conclusion: Within the limits of this study, it is concluded that mental depression significantly affects the periodontium. It may be considered as risk factor for periodontal disease.

  4. Control strategy of microbial fuel cell based on generalized predictive control%基于广义预测控制策略的微生物燃料电池控制

    Institute of Scientific and Technical Information of China (English)

    安爱民; 王静; 张浩琛; 杨国强; 刘云利

    2016-01-01

    The generalized predictive control is proposed that based on the control strategy of microbial fuel cell, combined with the characteristics of microbial fuel cells, to investigate the problems of unstable power output in the initial operation stage and the long adjustment time during the operation of an MFC, compared with the MFC system of PID control method joined, joined generalized predictive control of MFC system output is able to avoid the response greatly jitter and fast response, good robustness and dynamic adjustment to ensure that the dynamic output curve fast and accurate tracking system settings. The model identification is carried by the least squares method with forgetting factor to get linear model as a predictive model. Then, generalized predictive control (GPC) can adjust effectively the output response of an MFC under random influent flow at constant external resistance and acetate concentration. The simulation results show that GPC can achieve a good control effect and system robustness adjustment process has also been greatly improved in terms of speed control response. Effective implementation of the optimization of dynamic performance and robust performance of microbial fuel cell system to verify the proposed algorithm is effective and feasible.%针对 MFC 系统启动阶段输出响应不稳定以及调节时间较长的问题,结合微生物燃料电池自身特性,提出了基于广义预测控制(generalized predictive control,GPC)的微生物燃料电池(microbial fuel cell,MFC)控制策略。与加入PID控制方法对比得知,加入GPC的MFC系统输出能够避免响应出现大幅度的抖动,且响应速度快,动态调节鲁棒性好,保证了动态输出曲线快速准确地跟踪系统设定值。在给定外电阻为恒值和醋酸盐浓度随时间阶梯变化时,通过带遗忘因子的最小二乘法进行模型辨识,将所得线性模型作为预测模型,采用GPC算法进行控制。仿真表

  5. The extent of fermentative transformation of phenolic compounds in the bioanode controls exoelectrogenic activity in a microbial electrolysis cell.

    Science.gov (United States)

    Zeng, Xiaofei; Collins, Maya A; Borole, Abhijeet P; Pavlostathis, Spyros G

    2017-02-01

    Phenolic compounds in hydrolysate/pyrolysate and wastewater streams produced during the pretreatment of lignocellulosic biomass for biofuel production present a significant challenge in downstream processes. Bioelectrochemical systems are increasingly recognized as an alternative technology to handle biomass-derived streams and to promote water reuse in biofuel production. Thus, a thorough understanding of the fate of phenolic compounds in bioanodes is urgently needed. The present study investigated the biotransformation of three structurally similar phenolic compounds (syringic acid, SA; vanillic acid, VA; 4-hydroxybenzoic acid, HBA), and their individual contribution to exoelectrogenesis in a microbial electrolysis cell (MEC) bioanode. Fermentation of SA resulted in the highest exoelectrogenic activity among the three compounds tested, with 50% of the electron equivalents converted to current, compared to 12 and 9% for VA and HBA, respectively. The biotransformation of SA, VA and HBA was initiated by demethylation and decarboxylation reactions common to all three compounds, resulting in their corresponding hydroxylated analogs. SA was transformed to pyrogallol (1,2,3-trihydroxybenzene), whose aromatic ring was then cleaved via a phloroglucinol pathway, resulting in acetate production, which was then used in exoelectrogenesis. In contrast, more than 80% of VA and HBA was converted to catechol (1,2-dihydroxybenzene) and phenol (hydroxybenzene) as their respective dead-end products. The persistence of catechol and phenol is explained by the fact that the phloroglucinol pathway does not apply to di- or mono-hydroxylated benzenes. Previously reported, alternative ring-cleaving pathways were either absent in the bioanode microbial community or unfavorable due to high energy-demand reactions. With the exception of acetate oxidation, all biotransformation steps in the bioanode occurred via fermentation, independently of exoelectrogenesis. Therefore, the observed

  6. Factors Limiting Microbial Growth and Activity at a Proposed High-Level Nuclear Repository, Yucca Mountain, Nevada

    OpenAIRE

    Kieft, T. L.; Kovacik, W. P.; Ringelberg, D B; White, D. C.; Haldeman, D. L.; Amy, P S; Hersman, L. E.

    1997-01-01

    As part of the characterization of Yucca Mountain, Nev., as a potential repository for high-level nuclear waste, volcanic tuff was analyzed for microbial abundance and activity. Tuff was collected aseptically from nine sites along a tunnel in Yucca Mountain. Microbial abundance was generally low: direct microscopic cell counts were near detection limits at all sites (3.2 x 10(sup4) to 2.0 x 10(sup5) cells g(sup-1) [dry weight]); plate counts of aerobic heterotrophs ranged from 1.0 x 10(sup1) ...

  7. Virulence of Entomopathogenic Fungi Metarhizium anisopliae and Paecilomyces fumosoroseus for the Microbial Control of Spodoptera exigua.

    Science.gov (United States)

    Han, Ji Hee; Jin, Byung Rae; Kim, Jeong Jun; Lee, Sang Yeob

    2014-12-01

    The beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) is difficult to control using chemical insecticides because of the development of insecticide resistance. Several pest control agents are used to control the beet armyworm. Entomopathogenic fungi are one of the candidates for eco-friendly pest control instead of chemical control agents. In this study, among various entomopathogenic fungal strains isolated from soil two isolates were selected as high virulence pathogens against larva of beet armyworm. Control efficacy of fungal conidia was influenced by conidia concentration, temperature, and relative humidity (RH). The isolates Metarhizium anisopliae FT83 showed 100% cumulative mortality against second instar larvae of S. exigua 3 days after treatment at 1 × 10(7) conidia/mL and Paecilomyces fumosoroseus FG340 caused 100% mortality 6 days after treatment at 1 × 10(4) conidia/mL. Both M. anisopliae FT83 and P. fumosoroseus FG340 effectively controlled the moth at 20~30℃. M. anisopliae FT83 was significantly affected mortality by RH: mortality was 86.7% at 85% RH and 13.4% at 45% RH. P. fumosoroseus FG340 showed high mortality as 90% at 45% RH and 100% at 75% RH 6 days after conidia treatments. These results suggest that P. fumosoroseus FG340 and M. anisopliae FT83 have high potential to develop as a biocontrol agent against the beet armyworm.

  8. Optimal Control for Multistage Nonlinear Dynamic System of Microbial Bioconversion in Batch Culture

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2011-01-01

    Full Text Available In batch culture of glycerol biodissimilation to 1,3-propanediol (1,3-PD, the aim of adding glycerol is to obtain as much 1,3-PD as possible. Taking the yield intensity of 1,3-PD as the performance index and the initial concentration of biomass, glycerol, and terminal time as the control vector, we propose an optimal control model subject to a multistage nonlinear dynamical system and constraints of continuous state. A computational approach is constructed to seek the solution of the above model. Firstly, we transform the optimal control problem into the one with fixed terminal time. Secondly, we transcribe the optimal control model into an unconstrained one based on the penalty functions and an extension of the state space. Finally, by approximating the control function with simple functions, we transform the unconstrained optimal control problem into a sequence of nonlinear programming problems, which can be solved using gradient-based optimization techniques. The convergence analysis and optimality function of the algorithm are also investigated. Numerical results show that, by employing the optimal control, the concentration of 1,3-PD at the terminal time can be increased, compared with the previous results.

  9. Optimal control for nonlinear dynamical system of microbial fed-batch culture

    Science.gov (United States)

    Liu, Chongyang

    2009-10-01

    In fed-batch culture of glycerol bio-dissimilation to 1, 3-propanediol (1, 3-PD), the aim of adding glycerol is to obtain as much 1, 3-PD as possible. So a proper feeding rate is required during the process. Taking the concentration of 1, 3-PD at the terminal time as the performance index and the feeding rate of glycerol as the control function, we propose an optimal control model subject to a nonlinear dynamical system and constraints of continuous state and non-stationary control. A computational approach is constructed to seek the solution of the above model in two aspects. On the one hand we transcribe the optimal control model into an unconstrained one based on the penalty functions and an extension of the state space; on the other hand, by approximating the control function with simple functions, we transform the unconstrained optimal control problem into a sequence of nonlinear programming problems, which can be solved using gradient-based optimization techniques. The convergence analysis of this approximation is also investigated. Numerical results show that, by employing the optimal control policy, the concentration of 1, 3-PD at the terminal time can be increased considerably.

  10. Abiotic drivers and plant traits explain landscape-scale patterns in soil microbial communities.

    Science.gov (United States)

    de Vries, Franciska T; Manning, Pete; Tallowin, Jerry R B; Mortimer, Simon R; Pilgrim, Emma S; Harrison, Kathryn A; Hobbs, Phil J; Quirk, Helen; Shipley, Bill; Cornelissen, Johannes H C; Kattge, Jens; Bardgett, Richard D

    2012-11-01

    The controls on aboveground community composition and diversity have been extensively studied, but our understanding of the drivers of belowground microbial communities is relatively lacking, despite their importance for ecosystem functioning. In this study, we fitted statistical models to explain landscape-scale variation in soil microbial community composition using data from 180 sites covering a broad range of grassland types, soil and climatic conditions in England. We found that variation in soil microbial communities was explained by abiotic factors like climate, pH and soil properties. Biotic factors, namely community-weighted means (CWM) of plant functional traits, also explained variation in soil microbial communities. In particular, more bacterial-dominated microbial communities were associated with exploitative plant traits versus fungal-dominated communities with resource-conservative traits, showing that plant functional traits and soil microbial communities are closely related at the landscape scale.

  11. Microbially Induced Carbonate Precipitation: a Novel Grout for Permeability Control in Subsurface Engineering Works

    Science.gov (United States)

    Minto, J. M.; Hingerl, F.; Lunn, R. J.; Benson, S. M.

    2016-12-01

    ContextWe utilise the urea hydrolysing capability of soil bacteria Sporosarcina pasteurii to precipitate CaCO3 in a process termed Microbially Induced Carbonate Precipitation (MICP). MICP injection fluid properties are low particle size and low viscosity giving excellent grout penetrability. The CaCO3 grout has been shown to be effective at reducing permeability in porous and fractured media. MICP has consequently been proposed as an alternative to more traditional cement and chemical grouts, particularly in the fields of radioactive waste disposal and geological sequestration of CO2. This study investigates the role of fluid flow/CaCO3 feedback during precipitation and accelerated dissolution to better understand the longevity of an MICP grout under low pH environmental conditions such as found in a carbon sequestration reservoir. MethodsExperiments were conducted on a single Berea sandstone core in a high pressure core holder to characterise permeability, porosity and multiphase flow behaviour at sequestration reservoir temperature and pressure. Characterisation was carried out before MICP, after MICP, and after accelerated dissolution with hydrochloric acid. At each step the entire core was scanned in a medical x-ray CT scanner to spatially resolve (with a resolution of 0.5x0.5x1mm) the changes in porosity and saturation with CaCO3 precipitation and dissolution. Finally, the dried core was scanned with μ-CT at 30μm (full core) and 10μm (sub-volume) resolutions to investigate structural changes to the Berea at near pore scale. ResultsSix MICP treatment cycles over two days reduced core permeability from 886 mDarcy to 40 mDarcy with a greater reduction in porosity at the inlet. Dissolution with acid restored much of the porosity, but did not restore permeability to the same extent. Preferential flow paths formed during the dissolution step were visible in the first 4mm of the 100mm core, but did not extend further into the core. DiscussionThis study provides

  12. Human Factors Engineering Aspects of Modifications in Control Room Modernization

    Energy Technology Data Exchange (ETDEWEB)

    Hugo, Jacques; Clefton, Gordon; Joe, Jeffrey

    2017-06-01

    This report describes the basic aspects of control room modernization projects in the U.S. nuclear industry and the need for supplementary guidance on the integration of human factors considerations into the licensing and regulatory aspects of digital upgrades. The report pays specific attention to the integration of principles described in NUREG-0711 (Human Factors Engineering Program Review Model) and how supplementary guidance can help to raise general awareness in the industry regarding the complexities of control room modernization projects created by many interdependent regulations, standards and guidelines. The report also describes how human factors engineering principles and methods provided by various resources and international standards can help in navigating through the process of licensing digital upgrades. In particular, the integration of human factors engineering guidance and requirements into the process of licensing digital upgrades can help reduce uncertainty related to development of technical bases for digital upgrades that will avoid the introduction of new failure modes.

  13. Fermentation of a Malaysian Bacillus thuringiensis serotype H-14 isolate, a mosquito microbial control agent utilizing local wastes.

    Science.gov (United States)

    Lee, H L; Seleena, P

    1991-03-01

    A screening program searching for indigenous microbial control agents of mosquitos in Malaysia is initiated since 1987 and to date at least 20 isolates of mosquitocidal Bacillus thuringiensis serotypes have been obtained. Preliminary field evaluation of several isolates indicated that they are highly effective in the control of medically important mosquito species. For operational purposes, there is an urgent need to produce this agent utilizing cheap and locally available wastes through fermentation biotechnology. Fermentation studies in shake-flasks containing standard nutrient broth and soya bean waste, respectively, indicate that it takes about 37 hours for a Malaysian isolate of B. thuringiensis serotype H-14 to mature. In the grated coconut waste, fishmeal and rice bran, the bacteria took 28 hours, 26 hours and 126 hours respectively to mature. The endotoxin was harvested from the standard nutrient broth at 55 hours and at 50 hours from soybean, grated coconut waste and fishmeal. The endotoxin could only be harvested 150 hours after inoculation from rice bran medium. However, no bacterial growth was detected in palm oil effluent. In terms of endotoxin and biomass production, fishmeal appears to be a suitable medium. Variations in the pH of the fermenting media were also noted.

  14. Environmental factors controlling fluxes of dimethyl sulfide in a New Hampshire fen

    Science.gov (United States)

    Demello, William Zamboni; Hines, Mark E.

    1992-01-01

    The major environmental factors controlling fluxes of dimethyl sulfide (DMS) in a Sphagnum-dominated peatland were investigated in a poor fen in New Hampshire. DMS emissions from the surface of the peatland varied greatly over 24 hours and seasonally. Maximum DMS emissions occurred in summer with minima in the late fall. Temperature was the major environmental factor controlling these variabilities. There was also some evidence that the changes in water table height might have contributed to the seasonable variability in DMS emission. The influence of the water table was greater during periods of elevated temperature. DMS and MSH were the most abundant dissolved volatile sulfur compound (VSC) in the surface of the water table. Concentrations of dissolved VSC's varied with time and space throughout the fen. Dissolved MDS, MSH, and OCS in the surface of the water table were supersaturated with respect to their concentrations in the atmosphere suggesting that the peat surface was a source of VSC's in the peatland. VCS in peatlands seemed to be produced primarily by microbial processes in the anoxic surface layers of the peat rich in organic matter and inorganic sulfide. Sphagnum mosses were not a direct source of VSC's. However, they increased transport of DMS from the peat surface to the atmosphere.

  15. Vertical structure and pH as factors for chitinolytic and pectinolytic microbial community of soils and terrestrial ecosystems of different climatic zones

    Science.gov (United States)

    Lukacheva, Evgeniya; Natalia, Manucharova

    2016-04-01

    technique developed that is used to detect and localize the presence or absence of specific DNA sequences on chromosomes. pH as one of the factors which can have influence on degradation of biopolymers was studied for chitiolytic communities of different zones. And results were compared with direct studyings by method of "sowing" on a Petri dishes. Thus, we compared old classical methods with modern molecular studies. The difference between climatic zones was studied and the mathematical model was created. The mathematic model could be use in different aims, such as prognosis of microbial community composition and their classification.

  16. Neurotrophic Factor Control of Satiety and Body Weight

    Science.gov (United States)

    Xu, Baoji; Xie, Xiangyang

    2016-01-01

    Energy balance, the relationship between energy intake and expenditure, is regulated by a complex interplay of hormones, brain circuits and peripheral tissues. Leptin is an adipocyte-derived cytokine that suppresses appetite and increases energy expenditure. Ironically, obese individuals have high levels of plasma leptin and are resistant to leptin treatment. Neurotrophic factors, particularly ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF), are also important for the control of body weight. CNTF can overcome leptin resistance to reduce body weight, although CNTF and leptin activate similar signalling cascades. Mutations in the gene for BDNF lead to insatiable appetite and severe obesity. PMID:27052383

  17. Transcription Factor Zbtb20 Controls Regional Specification of Mammalian Archicortex

    DEFF Research Database (Denmark)

    Rosenthal, Eva Helga

    2010-01-01

    Combinatorial expression of sets of transcription factors (TFs) along the mammalian cortex controls its subdivision into functional areas. Unlike neocortex, only few recent data suggest genetic mechanisms controlling the regionalization of the archicortex. TF Emx2 plays a crucial role in patterning...... later on becoming restricted exclusively to postmitotic neurons of hippocampus (Hi) proper, dentate gyrus (DG), and two transitory zones, subiculum (S) and retrosplenial cortex (Rsp). Analysis of Zbtb20-/- mice revealed altered cortical patterning at the border between neocortex and archicortex...

  18. Factors controlling nitrous oxide at the microbial community and estuarine scale

    NARCIS (Netherlands)

    Bie, M.J.M. de; Middelburg, J.J.; Starink, M.; Laanbroek, H.J.

    2002-01-01

    This paper examines the effect of oxygen on nitrous oxide (N2O) concentrations in estuarine waters. N2O has been measured year-round in the Schelde estuary, a high-nitrogen, lowoxygen macrotidal system. N2O concentrations were above atmospheric equilibrium levels indicating that this estuary represe

  19. Factors controlling nitrous oxide at the microbial community and estuarine scale

    NARCIS (Netherlands)

    De Bie, M.J.M.; Middelburg, J.J.; Starink, Mathieu; Laanbroek, H.J.

    2002-01-01

    This paper examines the effect of oxygen on nitrous oxide (N2O) concentrations in estuarine waters. N2O has been measured year-round in the Schelde estuary, a high-nitrogen, low-oxygen macrotidal system. N2O concentrations were above atmospheric equilibrium levels indicating that this estuary repres

  20. Teleoperator hand controllers: A contextual human factors assessment

    Energy Technology Data Exchange (ETDEWEB)

    Draper, J.V.

    1994-05-01

    This document provides a human factors assessment of controllers for use with remotely controlled manipulators deployed to remove hazardous waste from underground storage tanks. The analysis concentrates on controller technique (i.e., the broad class of hand controller) and not on details of controller ergonomics. Examples of controller techniques include, for example, direct rate control, resolved unilateral position control, and direct bilateral position control. Using an existing concept, the Tank Waste Retrieval Manipulator System, as a reference, two basic types of manipulators may be identified for this application. A long reach, gross-positioning manipulator (LRM) may be used to position a smaller manipulator or an end-effector within a work site. For a Long Reach Manipulator, which will have an enormous motion range and be capable of high end-effector velocity, it will be safest and most efficient to use a resolved rate control system. A smaller, dexterous manipulator may be used to perform handling work within a relatively small work site, (i.e., to complete tasks requiring near-human dexterity). For a Dexterous Manipulator, which will have a smaller motion range than the LRM and be required to perform more difficult tasks, a resolved bilateral position control system will be safest and most efficient. However, during some waste recovery tasks it may be important to support the users by restricting movements to a single plane or axis. This can be done with a resolved bilateral position control system by (1) using the master controller force output to restrict controller inputs or (2) switching the controller to a multiaxis rate control mode and using the force output to provide a spring return to center functionality.

  1. At-Line Methods for Controlling Microbial Growth and Spoilage in Meat Processing Abattoirs

    Science.gov (United States)

    Fung, Daniel Y. C.; Edwards, Jessica R.; Crozier-Dodson, Beth Ann

    Many decontamination strategies are available to the meat industry for the control of spoilage and disease causing microorganisms. Most of these strategies are spraywash methods, and a variety of other methods are becoming increasingly popular in the industry as new research and developments are made. Hide-on decontamination has been shown to be extremely effective for controlling pathogens and may become more commonly incorporated into the hazard analysis and critical control point (HACCP) plans. A comprehensive review of decontamination of Escherichia coli O157:H7 in meat processing was made by Edwards and Fung (2006). The current chapter is for at-line consideration of all types of microorganisms related to meat processing with E. coli O157:H7 as the main model. Another detailed analysis of the entire topic of meat safety was made by Fung et al.

  2. Potential risk factors for diabetic neuropathy: a case control study

    Directory of Open Access Journals (Sweden)

    Nooraei Mahdi

    2005-12-01

    Full Text Available Abstract Background Diabetes mellitus type II afflicts at least 2 million people in Iran. Neuropathy is one of the most common complications of diabetes and lowers the patient's quality of life. Since neuropathy often leads to ulceration and amputation, we have tried to elucidate the factors that can affect its progression. Methods In this case-control study, 110 diabetic patients were selected from the Shariati Hospital diabetes clinic. Michigan Neuropathic Diabetic Scoring (MNDS was used to differentiate cases from controls. The diagnosis of neuropathy was confirmed by nerve conduction studies (nerve conduction velocity and electromyography. The multiple factors compared between the two groups included consumption of angiotensin converting enzyme inhibitors (ACEI, blood pressure, serum lipid level, sex, smoking, method of diabetes control and its quality. Results Statistically significant relationships were found between neuropathy and age, gender, quality of diabetes control and duration of disease (P values in the order: 0.04, 0.04, Conclusion In this study, hyperglycemia was the only modifiable risk factor for diabetic neuropathy. Glycemic control reduces the incidence of neuropathy, slows its progression and improves the diabetic patient's quality of life. More attention must be paid to elderly male diabetic patients with poor diabetes control with regard to regular foot examinations and more practical education.

  3. Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: Biogeochemical controls and associations with microbial communities

    Science.gov (United States)

    Lorah, M.M.; Voytek, M.A.

    2004-01-01

    The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens

  4. Vulnerability of Permafrost Soil Carbon to Climate Warming: Evaluating Controls on Microbial Community Composition

    Science.gov (United States)

    Abstract: Despite the fact that permafrost soils contain up to half of the carbon (C) in terrestrial pools, we have a poor understanding of the controls on decomposition in thawed permafrost. Global climate models assume that decomposition increases linearly with temperature, yet decomposition in th...

  5. Controlling herbicide-susceptible, -tolerant and -resistant weeds with microbial bioherbicides

    Science.gov (United States)

    The management of weeds is a necessary but expensive challenge. Public concerns of health, safety, and sustainability have increased interest in reducing the use of synthetic chemicals for weed control. Alternatives to chemical herbicides, such as bioherbicides, may offer an alternative to herbicide...

  6. Dominant factors in controlling marine gas pools in South China

    Science.gov (United States)

    Xu, S.; Watney, W.L.

    2007-01-01

    In marine strata from Sinian to Middle Triassic in South China, there develop four sets of regional and six sets of local source rocks, and ten sets of reservoir rocks. The occurrence of four main formation periods in association with five main reconstruction periods, results in a secondary origin for the most marine gas pools in South China. To improve the understanding of marine gas pools in South China with severely deformed geological background, the dominant control factors are discussed in this paper. The fluid sources, including the gas cracked from crude oil, the gas dissolved in water, the gas of inorganic origin, hydrocarbons generated during the second phase, and the mixed pool fluid source, were the most significant control factors of the types and the development stage of pools. The period of the pool formation and the reconstruction controlled the pool evolution and the distribution on a regional scale. Owing to the multiple periods of the pool formation and the reconstruction, the distribution of marine gas pools was complex both in space and in time, and the gas in the pools is heterogeneous. Pool elements, such as preservation conditions, traps and migration paths, and reservoir rocks and facies, also served as important control factors to marine gas pools in South China. Especially, the preservation conditions played a key role in maintaining marine oil and gas accumulations on a regional or local scale. According to several dominant control factors of a pool, the pool-controlling model can be constructed. As an example, the pool-controlling model of Sinian gas pool in Weiyuan gas field in Sichuan basin was summed up. ?? Higher Education Press and Springer-Verlag 2007.

  7. Dominant factors in controlling marine gas pools in South China

    Institute of Scientific and Technical Information of China (English)

    XU Sihuang; W.Lynn Watney

    2007-01-01

    In marine strata from Sinian to Middle Triassic in South China,there develop four sets of regional and six sets of local source rocks,and ten sets of reservoir rocks.The occurrence of four main formation periods in association with five main reconstruction periods,results in a secondary origin for the most marine gas pools in South China.To improve the understanding of marine gas pools in South China with severely deformed geological background,the dominant control factors are discussed in this paper.The fluid sources,including the gas cracked from crude oil,the gas dissolved in water,the gas of inorganic origin,hydrocarbons generated during the second phase,and the mixed pool fluid source,were the most significant control factors of the types and the development stage of pools.The period of the pool formation and the reconstruction controlled the pool evolution and the distribution on a regional scale.Owing to the multiple periods of the pool formation and the reconstruction,the distribution of marine gas pools was complex both in space and in time,and the gas in the pools is heterogeneous.Pool elements,such as preservation conditions,traps and migration paths,and reservoir rocks and facies,also served as important control factors to marine gas pools in South China.Especially,the preservation conditions played a key role in maintaining marine oil and gas accumulations on a regional or local scale.According to several dominant control factors of a pool,the pool-controlling model can be constructed.As an example,the pool-controlling model of Sinian gas pool in Weiyuan gas field in Sichuan basin was summed up.

  8. Physiology and Endocrinology Symposium. Factors controlling puberty in beef heifers

    Science.gov (United States)

    The Physiology and Endocrinology Symposium on “Factors controlling puberty in beef heifers” was held at the joint annual meeting of the American Dairy Science Association and the American Society of Animal Science in New Orleans, Louisiana, USA, July 10 to 14, 2011. The objective of the symposium w...

  9. Responses of Lens esculenta Moench to controlled environmental factors

    NARCIS (Netherlands)

    Saint-Clair, P.M.

    1972-01-01

    Many experiments were undertaken to study the responses of the lentil cultivars 'Large blonde' and 'Anicia' to controlled environmental factors. They covered different aspects of the physiology and the ecology of the crop.The orientation experiments (2) involved germination and depth of sowing. The

  10. Simple Expressions for Safety Factors in Inventory Control

    NARCIS (Netherlands)

    Strijbosch, L.W.G.; Moors, J.J.A.

    1999-01-01

    The literature on inventory control discusses many methods to establish the level of decision parameters -like reorder levels or safety factors-, necessary to attain a prescribed service level. In general, however, these methods are not easy applicable: they often use time-consuming iterations, requ

  11. Behavioural factors related to metabolic control in patients with phenylketonuria

    NARCIS (Netherlands)

    Crone, MR; van Spronsen, FJ; Oudshoorn, K; Bekhof, J; van Rijn, G; Verkerk, PH

    2005-01-01

    Background. The objective of this study was to determine the importance of parental factors possibly related to dietary control in early and continuously treated patients with phenylketonuria (PKU). Methods. A questionnaire was disseminated among parents of 238 patients with PKU born after the natio

  12. Designing Simulation Experiments with Controllable and Uncontrollable Factors

    DEFF Research Database (Denmark)

    Dehlendorff, Christian; Kulahci, Murat; Andersen, Klaus Kaae

    In this study we propose a new method for designing computer experiments inspired by the split plot designs used in physical experimentation. The basic layout is that each set of controllable factor settings corresponds to a whole plot for which a number of subplots, each corresponding to one...... combination of settings of the uncontrollable factors, is employed. The caveat is a desire that the subplots within each whole plot cover the design space uniformly. A further desire is that in the combined design, where all experimental runs are considered at once, the uniformity of the design space coverage...... should be guaranteed. Our proposed method allows for a large number of uncontrollable and controllable settings to be run in a limited number of runs while uniformly covering the design space for the uncontrollable factors....

  13. Microbial control of the invasive spiraling whitefly on cassava with entomopathogenic fungi

    OpenAIRE

    Boopathi, Thangavel; Karuppuchamy,Palaniappan; Singh,Soibam B.; Kalyanasundaram, Manickavasagam; S. Mohankumar; Ravi,Madhaiyan

    2015-01-01

    Abstract The entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae, Lecanicillium lecanii and Isaria fumosorosea were tested for their efficacy in managing the exotic spiraling whitefly Aleurodicus dispersus (Hemiptera, Aleyrodidae) on cassava (Manihot esculenta) during 2 seasons (2011-2012 and 2012-2013). The fungi I. fumosorosea and L. lecanii exhibited promising levels of control (> 70% mortality of the A. dispersus population). The percent mortality increased over time in both...

  14. Factors controlling accumulation of soil organic carbon along vegetation succession in a typical karst region in Southwest China

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shujuan [Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125 (China); Huanjiang Observation and Research Station of Karst Ecosystem, Chinese Academy of Sciences, Huanjiang, Guangxi Zhuang Autonomous Region 547100 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Wei [Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125 (China); Huanjiang Observation and Research Station of Karst Ecosystem, Chinese Academy of Sciences, Huanjiang, Guangxi Zhuang Autonomous Region 547100 (China); Wang, Kelin, E-mail: kelin@isa.ac.cn [Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125 (China); Huanjiang Observation and Research Station of Karst Ecosystem, Chinese Academy of Sciences, Huanjiang, Guangxi Zhuang Autonomous Region 547100 (China); Pan, Fujing [Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125 (China); Huanjiang Observation and Research Station of Karst Ecosystem, Chinese Academy of Sciences, Huanjiang, Guangxi Zhuang Autonomous Region 547100 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Yang, Shan [Changsha university, Changsha 410003 (China); Shu, Shiyan [Changjiang Project Supervision & Consultancy Co. Ltd, Wuhan 430010 (China); Changjiang Ecology (Hubei) Technology Development LLC, Wuhan 430010 (China)

    2015-07-15

    Vegetation succession enhances the accumulation of carbon in the soil. However, little is known about the mechanisms underlying soil organic carbon (SOC) accumulation in different vegetation types in the karst region of Southwest China. The goal of this study was to identify and prioritize the effects of environmental parameters, including soil physico-chemical properties, microbial biomass, enzyme activities, and litter characteristics, on SOC accumulation along a vegetation succession sere (grassland, shrubland, secondary forest, and primary forest) in the karst landscape of Southwest China. Relationships between these parameters and SOC were evaluated by redundancy analysis. The results showed that SOC accumulation was significantly different among vegetation types (P < 0.01) and increased with vegetation succession (from 29.10 g·kg{sup −1} in grassland to 73.92 g·kg{sup −1} in primary forest). Soil biochemistry and physical characteristics significantly affected the accumulation of SOC. Soil microbial biomass showed a predominant effect on SOC in each of the four vegetation types. In addition, the soil physical property (especially the silt content) was another controlling factor in the early stages (grassland), and urease activity and saccharase activity were important controlling factors in the early-middle and middle-late stages, respectively. Litter characteristics only showed mild effects on SOC accumulation. Variation partitioning analysis showed that the contribution of sole main factors to SOC variation decreased, while the interaction effect among parameters increased along the succession gradient. - Highlights: • Vegetation restoration is conducive to soil carbon sequestration in karst areas. • The factors controlling SOC accumulation differed along vegetation succession. • The interaction effect among significant factors became more and more prominent along succession.

  15. Biosecurity and Disinfection Controls of Poultry Microbial Pathogen Infections in Nigeria

    Directory of Open Access Journals (Sweden)

    Irene U. Chima

    2012-03-01

    Full Text Available In Nigeria, industrial poultry production occupies a place of pride among the livestock enterprises due to its rapid monetary turnover. However, Intensive poultry farming provides the optimum conditions for the concentration of disease causing pathogens and transmission. The presence of these diseases has created the need for the control of poultry pathogens in the intensive farming system. Microbiological contamination can be prevented and controlled using proper management practices and healthcare products such as disinfectants. Disinfection consists of destroying disease-producing microbes by chemical and physical means. Hygiene involves the setting up of physical barriers to restrict the access of disease causing agents to the flock and to limit the spread of infectious materials. Biosecurity on the other hand is the protection of poultry flock from any type of infectious agents, whether viral, bacterial, fungi or parasitic in nature. In many developing countries, such as Nigeria, provision for biosecurity are usually inadequate due to; outdated laws and inadequate legal infrastructure; lack of resources, budget and infrastructure for inspection and enforcement; poor cooperation between agencies; lack of technical resources and infrastructure for risk assessment, etc. Measures to enhance safety of food and good quality poultry products from farm to table are however key concerns for all stakeholders in the industry. Since Global concerns about poultry pathogen play a prime role in poultry exports and food policy decisions in international trade, Nigerian poultry farmers need proper diseases control environment in order to sustain asses to international trade.

  16. Comparing a microbial biocide and chlorine as zebra mussel control strategies in an Irish drinking water treatment plant

    Directory of Open Access Journals (Sweden)

    Sara Meehan

    2013-06-01

    Full Text Available A need exists for an environmentally friendly mussel control method to replace chlorine and other traditional control methods currentlyutilised in drinking water plants and other infested facilities. Zequanox® is a newly commercialised microbial biocide for zebra and quaggamussels comprised of killed Pseudomonas fluorescens CL145A cells. The objective of this study was to compare the efficacy of adevelopmental formulation of Zequanox (referred to as MBI 401 FDP and chlorine treatments on adult and juvenile zebra mussels byrunning a biobox trial in conjunction with chlorine treatments at an infested Irish drinking water treatment plant. Since 2009, the plantmanagement has used a residual chlorine concentration of 2 mg/L in autumn to control both adult zebra mussels and juvenile settlement intheir three concrete raw water chambers. Juvenile mussel settlement was monitored in three bioboxes as well as in three treatment chambersin the plant for three months prior to treatment. Adult mussels were seeded into the chambers and bioboxes four days before treatment. InOctober 2011, the bioboxes were treated with MBI 401 FDP at 200 mg active substance/L, while chlorine treatment took place in the waterchambers. The MBI 401 FDP treatment lasted only 8 hours while chlorine treatment lasted seven days. Juvenile numbers were reduced tozero in both the bioboxes and treated chambers within seven days. Adult mussel mortality reached 80% for both the chlorine and MBI 401FDP treatment; however, mortality was achieved faster in the chlorine treatment. These results provided important insights into zebra musselcontrol alternatives to chlorine and supported further development of the now commercial product, Zequanox.

  17. Assessment of microbial community changes and limiting factors during bioremediation of hydrocarbon-polluted soil with new miniaturized physiological methods

    OpenAIRE

    Kaufmann, Karin; Holliger, Hans Christof

    2005-01-01

    Due to human activities, organic pollutants are spilled to the environment where they threaten public health, often as contaminants of soil or groundwater. Living organisms are able to transform or mineralize many organic pollutants, and bioremediation techniques have been developed to remove pollutants from a contaminated site. However, fast and easy methods to document both the efficacy of bioremediation and the changes in soil microbial communities during bioremediation are not well develo...

  18. Controlled modification of carbon nanotubes and polyaniline on macroporous graphite felt for high-performance microbial fuel cell anode

    Science.gov (United States)

    Cui, Hui-Fang; Du, Lin; Guo, Peng-Bo; Zhu, Bao; Luong, John H. T.

    2015-06-01

    Polyaniline (PANI) was electropolymerized on the surface of macroporous graphite felt (GF) followed by the electrophoretic deposition of carbon nanotubes (CNTs). The as-prepared macroporous material was characterized by scanning electron microscopy, water contact angle goniometry and electrochemical techniques. Upon the modification of PANI, a rough and nano-cilia containing film is coated on the surface of the graphite fibers, transforming the surface from hydrophobic to hydrophilic. The subsequent modification by CNTs increases the effective surface area and electrical conductivity of the resulting material. The power output of a mediator-free dual-chamber microbial fuel cell (MFC) constructed from the GF anode and an exoelectrogen Shewanella putrefaciens increases drastically with the CNT modification. The CNT/PANI/GF MFC attains an output voltage of 342 mV across an external resistor of 1.96 kΩ constant load, and a maximum power density of 257 mW m-2, increased by 343% and 186%, compared to that of the pristine GF MFC and the PANI/GF MFC, respectively. More bacteria are attached on the CNT/PANI/GF anode than on the PANI/GF anode during the working of the MFC. This strategy provides an easy scale-up, simple and controllable method for the preparation of high-performance and low-cost MFC anodes.

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

    Science.gov (United States)

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

    2014-04-01

    Characterizing ecological relationships between viruses, bacteria and protists in the ocean are critical to understanding ecosystem function, yet these relationships are infrequently investigated together. We evaluated these relationships through microbial association network analysis of samples collected approximately monthly from March 2008 to January 2011 in the surface ocean (0-5 m) at the San Pedro Ocean Time series station. Bacterial, T4-like myoviral and protistan communities were described by Automated Ribosomal Intergenic Spacer Analysis and terminal restriction fragment length polymorphism of the gene encoding the major capsid protein (g23) and 18S ribosomal DNA, respectively. Concurrent shifts in community structure suggested similar timing of responses to environmental and biological parameters. We linked T4-like myoviral, bacterial and protistan operational taxonomic units by local similarity correlations, which were then visualized as association networks. Network links (correlations) potentially represent synergistic and antagonistic relationships such as viral lysis, grazing, competition or other interactions. We found that virus-bacteria relationships were more cross-linked than protist-bacteria relationships, suggestive of increased taxonomic specificity in virus-bacteria relationships. We also found that 80% of bacterial-protist and 74% of bacterial-viral correlations were positive, with the latter suggesting that at monthly and seasonal timescales, viruses may be following their hosts more often than controlling host abundance.

  20. Risk factors of Cancer Prostate A case control study.

    Science.gov (United States)

    Kamel, Nahed M; Tayel, Eiman S; El Abbady, Ahmed A; Khashab, Sahar S

    2006-01-01

    The purpose of this study is to reveal the different risk factors related to this cancer particularly that there is no agreement about which factors affect the risk. A fishing expedition hospital based case control study was carried out. Cases and controls were identified from the Urology Department of Alexandria Main University Hospital, 2004. All cases diagnosed as having the tumor were included in the case series. For each case the second subject proved to have a negative pathological examination was included in the control group (50).Data collection was carried out blindly using a structured interview schedule. Analysis was applied using Chi-square test, Fisher exact and Student's t-test. Odds Ratios and 95% Confidence Intervals were calculated. Results indicated that regular consumption of sausages was greater among cases than controls (X(2)= 10.19, p= 0.001 and an odds ratio of 5.92 (CI: 1.69-25.99). Also more cases claimed consuming regularly butter and natural ghee than controls (X(2)= 5.47, p= 0.019). The estimate risk was as high as 2.79 (Cl: 1.07-7.33). However regular consumption of vegetables was more encountered among controls than cases (X(2) = 5.005, p= 0.025 where the odds ratio was 0.19 (Cl: 0.02-1.01). Moreover the multiple regression analysis confirmed the results obtained from univariate analysis. The consistency of results of current work as regards sausages and butter with several other research works can support the identification of these specific possible risk factors. Also other research workers pointed out to the protective effect of vegetables. However further research is needed to address other risk factors.

  1. How do changes in dissolved oxygen concentration influence microbially-controlled phosphorus cycling in stream biofilms?

    Science.gov (United States)

    Saia, S. M.; Locke, N. A.; Regan, J. M.; Carrick, H. J.; Buda, A. R.; Walter, M. T.

    2014-12-01

    Advances in molecular microbiology techniques (e.g. epi-fluorescent microscopy and PCR) are making it easier to study the influence of specific microorganisms on nutrient transport. Polyphosphate accumulating organisms (PAOs) are commonly used in wastewater treatment plants to remove excess phosphorus (P) from effluent water. PAOs have also been identified in natural settings but their ecological function is not well known. In this study, we tested the hypothesis that PAOs in natural environments would release and accumulate P during anaerobic and aerobic conditions, respectively. We placed stream biofilms in sealed, covered tubs and subjected them to alternating air (aerobic conditions) and N2 gas (anaerobic condition) bubbling for 12 hours each. Four treatments investigated the influence of changing dissolved oxygen on micribially-controlled P cycling: (1) biofilms bubbled continuously with air, (2) biofilms bubbled alternatively with air and N2, (3) biocide treated biofilms bubbled continuously with air, and (4) biocide treated biofilms bubbled alternatively with air and N2. Treatments 3 and 4 serve as abiotic controls to treatments 1 and 2. We analyzed samples every 12 hours for soluble reactive P (SRP), temperature, dissolved oxygen, and pH. We also used fluorescent microscopy (i.e. DAPI staining) and PCR to verify the presence of PAOs in the stream biofilms. SRP results over the course of the experiment support our hypothesis that anaerobic and aerobic stream conditions may impact PAO mediated P release and uptake, respectively in natural environments. The results of these experiments draw attention to the importance of microbiological controls on P mobility in freshwater ecosystems.

  2. Simplifying the audit of risk factor recording and control

    DEFF Research Database (Denmark)

    Zhao, Min; Cooney, Marie Therese; Klipstein-Grobusch, Kerstin

    2016-01-01

    BACKGROUND: To simplify the assessment of the recording and control of coronary heart disease risk factors in different countries and regions. DESIGN: The SUrvey of Risk Factors (SURF) is an international clinical audit. METHODS: Data on consecutive patients with established coronary heart disease...... from countries in Europe, Asia and the Middle East were collected on a one-page collection sheet or electronically during routine clinic visits. Information on demographics, diagnostic category, risk factors, physical and laboratory measurements, and medications were included and key variables...... summarized in a Cardiovascular Health Index Score. RESULTS: Coronary heart disease patients (N = 10,186; 29% women) were enrolled from 79 centres in 11 countries. Recording of risk factors varied considerably: smoking was recorded in over 98% of subjects, while about 20% lacked data on laboratory...

  3. Risk factors for anal fistula: a case-control study.

    Science.gov (United States)

    Wang, D; Yang, G; Qiu, J; Song, Y; Wang, L; Gao, J; Wang, C

    2014-07-01

    The aim of our study was to identify potential risk factors for anal fistula in order to improve prevention and treatment of anal fistula. A retrospective case-control study for anal fistula was conducted at our unit. Logistic regression analyses were carried out to identify associated risk factors for anal fistula. The final model obtained by the stepwise forward logistic regression analysis method identified the following items as independent risk factors: body mass index of >25.0 kg/m(2), high daily salt intake, history of diabetes, hyperlipidemia, dermatosis, anorectal surgery, history of smoking and alcohol intake, sedentary lifestyle, excessive intake of spicy/greasy food, very infrequent participation in sports and prolonged sitting on the toilet for defecation. Our results indicate that lifestyle factors and certain medical conditions increase an individual's risk of developing anal fistula.

  4. A microbial avenue to cell cycle control in the plant superkingdom.

    Science.gov (United States)

    Tulin, Frej; Cross, Frederick R

    2014-10-01

    Research in yeast and animals has resulted in a well-supported consensus model for eukaryotic cell cycle control. The fit of this model to early diverging eukaryotes, such as the plant kingdom, remains unclear. Using the green alga Chlamydomonas reinhardtii, we developed an efficient pipeline, incorporating robotics, semiautomated image analysis, and deep sequencing, to molecularly identify >50 genes, mostly conserved in higher plants, specifically required for cell division but not cell growth. Mutated genes include the cyclin-dependent kinases CDKA (resembling yeast and animal Cdk1) and the plant-specific CDKB. The Chlamydomonas cell cycle consists of a long G1 during which cells can grow >10-fold, followed by multiple rapid cycles of DNA replication and segregation. CDKA and CDKB execute nonoverlapping functions: CDKA promotes transition between G1 and entry into the division cycle, while CDKB is essential specifically for spindle formation and nuclear division, but not for DNA replication, once CDKA-dependent initiation has occurred. The anaphase-promoting complex is required for similar steps in the Chlamydomonas cell cycle as in Opisthokonts; however, the spindle assembly checkpoint, which targets the APC in Opisthokonts, appears severely attenuated in Chlamydomonas, based on analysis of mutants affecting microtubule function. This approach allows unbiased integration of the consensus cell cycle control model with innovations specific to the plant lineage.

  5. Microbial pathogens in raw pork, chicken, and beef: benefit estimates for control using irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, T.

    1985-12-01

    Various control procedures have been suggested for reducing foodborne infectious diseases. Receiving considerable attention is irradiation. This report estimates the medical and wage (or productivity) benefits associated with prevention of five human diseases transmitted by beef, pork, and chicken. (These diseases can also be transmitted by other vectors, such as eggs, milk, and pets. But these sources are not included in the analysis.) All of these foodborne infectious diseases - salmonellosis, campylobacteriosis, trichinosis, tapeworm, and toxoplasmosis - could be significantly reduced by irradiating meat and poultry. The Food and Drug Administration (FDA) has just approved irradiation of pork to prevent trichinosis (50FR 29658-59) and is considering approval of irradiation of chicken to kill Salmonella. 22 references.

  6. Microbial control of the invasive spiraling whitefly on cassava with entomopathogenic fungi.

    Science.gov (United States)

    Boopathi, Thangavel; Karuppuchamy, Palaniappan; Singh, Soibam B; Kalyanasundaram, Manickavasagam; Mohankumar, S; Ravi, Madhaiyan

    2015-01-01

    The entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae, Lecanicillium lecanii and Isaria fumosorosea were tested for their efficacy in managing the exotic spiraling whitefly Aleurodicus dispersus (Hemiptera, Aleyrodidae) on cassava (Manihot esculenta) during 2 seasons (2011-2012 and 2012-2013). The fungi I. fumosorosea and L. lecanii exhibited promising levels of control (> 70% mortality of the A. dispersus population). The percent mortality increased over time in both seasons. Application of I. fumosorosea was highly pathogenic to A. dispersus in both seasons compared to the other entomopathogenic fungi. Analysis of the percent mortality in both seasons revealed differences in efficacy between 3 and 15 days after treatment. The season also influenced the effects of the fungi on the A. dispersus population. Thus, entomopathogenic fungi have the potential to manage A. dispersus infestation of cassava.

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

    Science.gov (United States)

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

    1990-03-01

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

  8. Control of aerosol contaminants in indoor air: combining the particle concentration reduction with microbial inactivation.

    Science.gov (United States)

    Grinshpun, Sergey A; Adhikari, Atin; Honda, Takeshi; Kim, Ki Youn; Toivola, Mika; Rao, K S Ramchander; Reponen, Tiina

    2007-01-15

    An indoor air purification technique, which combines unipolar ion emission and photocatalytic oxidation (promoted by a specially designed RCI cell), was investigated in two test chambers, 2.75 m3 and 24.3 m3, using nonbiological and biological challenge aerosols. The reduction in particle concentration was measured size selectively in real-time, and the Air Cleaning Factor and the Clean Air Delivery Rate (CADR) were determined. While testing with virions and bacteria, bioaerosol samples were collected and analyzed, and the microorganism survival rate was determined as a function of exposure time. We observed that the aerosol concentration decreased approximately 10 to approximately 100 times more rapidly when the purifier operated as compared to the natural decay. The data suggest that the tested portable unit operating in approximately 25 m3 non-ventilated room is capable to provide CADR-values more than twice as great than the conventional closed-loop HVAC system with a rating 8 filter. The particle removal occurred due to unipolar ion emission, while the inactivation of viable airborne microorganisms was associated with photocatalytic oxidation. Approximately 90% of initially viable MS2 viruses were inactivated resulting from 10 to 60 min exposure to the photocatalytic oxidation. Approximately 75% of viable B. subtilis spores were inactivated in 10 min, and about 90% or greater after 30 min. The biological and chemical mechanisms that led to the inactivation of stress-resistant airborne viruses and bacterial spores were reviewed.

  9. Factores de necesidad asociados al uso adecuado del control prenatal

    Directory of Open Access Journals (Sweden)

    Clarybel Miranda Mellado

    2016-07-01

    Full Text Available Introducción: Por las implicaciones sociales de la mortalidad y morbilidad materna es importante determinar los factores de necesidad que influyen en el uso adecuado del control prenatal en gestantes de Sincelejo. Materiales y Métodos: Estudio analítico de corte transversal, que incluyó 730 gestantes, seleccionadas mediante muestreo aleatorio por conglomerados, de las comunas de la ciudad. La información fue recolectada por medio de una encuesta sociodemográfica, una ficha de uso de control prenatal y un Cuestionario para evaluar los factores de necesidad  propuestos por el Modelo de Promoción de la Salud de Nola Pender. Las gestantes fueron contactadas en sus domicilios y diligenciaron los instrumentos. Los datos fueron analizados aplicando estadística descriptiva e inferencial para determinar las asociaciones entre variables. Resultados: El 97,7% (713 de las gestantes asistía al control prenatal, con una mediana de 4 controles prenatales. Un 2,3% (17 no lo habían iniciado al momento de la encuesta y 24,4% (178 hizo uso inadecuado. El 80,7% (589 de las gestantes califican su estado de salud como bueno o muy bueno, 94,8% (692 percibieron beneficios del control prenatal. Se encontró asociación significativa entre la percepción de beneficios y el uso adecuado de control prenatal [OR=5,5 (IC 95%: 2,8 - 10,8]. Discusión y Conclusiones: La percepción que las mujeres tienen sobre los buenos resultados que reporta la asistencia al control prenatal, es el principal factor que puede explicar la adherencia al control y el cumplimiento regular de las consultas. Cómo citar este artículo: Miranda C, Castillo IY. Factores de necesidad asociados al uso adecuado del control prenatal. Rev Cuid. 2016; 7(2: 1345-51. http://dx.doi.org/10.15649/cuidarte.v7i2.340

  10. Environmental controls on photosynthetic microbial mat distribution and morphogenesis on a 3.42 Ga clastic-starved platform.

    Science.gov (United States)

    Tice, Michael M

    2009-12-01

    Three morphotypes of microbial mats are preserved in rocks deposited in shallow-water facies of the 3.42 Ga Buck Reef chert (BRC). Morphotype alpha consists of fine anastomosing and bifurcating carbonaceous laminations, which loosely drape underlying detrital grains or form silica-filled lenses. Morphotype beta consists of meshes of fine carbonaceous strands intergrown with detrital grains and dark laminations, which loosely drape coarse detrital grains. Morphotype gamma consists of fine, even carbonaceous laminations that tightly drape underlying detrital grains. Preservation of nearly uncompacted mat morphologies and detrital grains deposited during mat growth within a well-characterized sedimentary unit makes quantitative correlation between morphology and paleoenvironment possible. All mats are preserved in the shallowest-water interval of those rocks deposited below normal wave base and above storm wave base. This interval is bounded below by a transgressive lag formed during regional flooding and above by a small condensed section that marks a local relative sea-level maximum. Restriction of all mat morphotypes to the shallowest interval of the storm-active layer in the BRC ocean reinforces previous interpretations that these mats were constructed primarily by photosynthetic organisms. Morphotypes alpha and beta dominate the lower half of this interval and grew during deposition of relatively coarse detrital carbonaceous grains, while morphotype gamma dominates the upper half and grew during deposition of fine detrital carbonaceous grains. The observed mat distribution suggests that either light intensity or, more likely, small variations in ambient current energy acted as a first-order control on mat morphotype distribution. These results demonstrate significant environmental control on biological morphogenetic processes independent of influences from siliciclastic sedimentation.

  11. Microbial conversion of tomato by a plant pathogenic bacterium Pectobacterium atrosepticum: a plant-microbial approach to control pathogenic Candida species.

    Science.gov (United States)

    Bajpai, Vivek K; Kang, Sun Chul; Lee, Soon-Gu; Baek, Kwang-Hyun

    2012-01-01

    This study was carried out to produce bioconverted products by microbial fermentation of tomato using a plant pathogenic bacterium Pectobacterium atrosepticum and to evaluate their in vitro antimycotic effect against pathogenic Candida species. The bioconverted products (500 microg/disc) provoked promising antimycotic effects against pathogenic isolates of Candida species as shown by the diameters of zones of inhibition (9 +/- 0.6 to 14 +/- 0.4 mm), along with their respective minimum inhibitory and minimum fungicidal concentration values, which increased from 250 to 1000 and 250 to 2000 microg/mL, respectively. With the viable counts of the tested fungal pathogens, exposure of the bioconverted products revealed a remarkable antimycotic effect. In addition, the morphology of a clinical isolate of C. glabrata KBN06P00368, visualized by scanning electron microscopy, showed a severe detrimental effect produced by the bioconverted products at the minimum inhibitory concentration (250 microg/mL). The bioconverted products significantly inhibited the in vitro growth of all the tested clinical and pathogenic laboratory isolates of Candida species. This study confirmed the potent antimycotic efficacy of the bioconverted products of tomato, hence justifying the therapeutic uses of bioconverted products in pharmaceutical preparations as an alternative approach to support the antifungal activity of conventional antimycotics.

  12. Interventions for control of Salmonella: clearance of microbial growth from rubber picker fingers.

    Science.gov (United States)

    Arnold, J W; Yates, I E

    2009-06-01

    A study was conducted to determine if a surface material with antimicrobial properties combined with an effective disinfectant could achieve total clearance of bacterial contamination. Before beginning the project, new rubber picker fingers collected from 3 processing facilities were tested for endogenous microflora. Five species of bacteria common to soil and human handling were present: Bacillus amyloliquefaciens, Bacillus cereus/thuringiensis, Staphylococcus epidermidis, Staphylococcus hominis ssp. novobiosepticus, and Staphylococcus intermedius. In separate experiments, new (unused) rubber picker fingers from 3 manufacturers were exposed to broiler carcass rinses, and the kinetics of bacterial attachment to finger material was determined. Turbidity of the bacterial suspensions at varying dilutions containing picker finger sections was compared hourly with controls to evaluate inhibition. New rubber finger material from the 3 manufacturers significantly inhibited bacterial growth (P growth of pathogens and determined the activity of 5 disinfectant compounds. Two of the compounds were most effective against Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, Salmonella Enteritidis, and Escherichia coli, and one of the compounds was selected for further study with Salmonella Enteritidis. Scanning electron microscopy confirmed the levels of Salmonella Enteritidis before and after treatment. The most effective compound was nontoxic and completely cleared Salmonella Enteritidis contamination from the rubber picker finger surface.

  13. Enhanced catalytic activity and inhibited biofouling of cathode in microbial fuel cells through controlling hydrophilic property

    Science.gov (United States)

    Li, Da; Liu, Jia; Wang, Haiman; Qu, Youpeng; Zhang, Jie; Feng, Yujie

    2016-11-01

    The hydrophilicity of activated carbon cathode directly determines the distribution of three-phase interfaces where oxygen reduction occurs. In this study, activated carbon cathodes are fabricated by using hydrophobic polytetrafluoroethylene (PTFE) and amphiphilic LA132 at various weight ratio to investigate the effect of hydrophilic property on cathode performance. Contact angle tests confirm the positive impact of LA132 content on hydrophilicity. Cathode with 67 wt% LA132 content shows the highest electrochemical activity as exchange current density increases by 71% and charge transfer resistance declines by 44.6% compared to that of PTFE cathode, probably due to the extended reaction interfaces by optimal hydrophilicity of cathode so that oxygen reduction is facilitated. As a result, the highest power density of 1171 ± 71 mW m-2 is obtained which is 14% higher than PTFE cathode. In addition to the hydrophilicity, this cathode had more negative charged surface of catalyst layer, therefore the protein content of cathodic biofilm decreased by 47.5%, indicating the effective bacterial inhibition when 67 wt% LA132 is used. This study shows that the catalytic activity of cathode is improved by controlling proper hydrophilicity of cathode, and that biofilm can be reduced by increasing hydrophilicity and lowering the surface potential.

  14. Risk factors for episiotomy: a case-control study

    Directory of Open Access Journals (Sweden)

    Giordana Campos Braga

    2014-10-01

    Full Text Available Objective: obtaining information on the factors associated with episiotomy will be useful in sensitizing professionals to the need to minimize its incidence. Therefore, the objective of this study was to evaluate risk factors for episiotomy in pregnant women who had undergone vaginal delivery at a university maternity hospital in northeastern Brazil. Methods: a case-control study was conducted with pregnant women submitted to episiotomy (cases and pregnant women not submitted to episiotomy (controls between March 2009 and July 2010 at the Professor Fernando Figueira Integral Medicine Institute (IMIP in Recife, Brazil, in a ratio of 1 case to 2 controls. The study variables consisted of: whether episiotomy was performed, demographic, obstetric and fetal characteristics (primiparity, analgesia, instrumental delivery, fetal distress, etc., external factors (day and time of delivery, professional attending delivery and factors directly related to delivery. Odds ratios (OR and 95% confidence intervals (95%CI were calculated. Multivariate analysis was performed to determine the adjusted risk of episiotomy. Results: a total of 522 women (173 cases and 349 controls were included. It was found that deliveries with episiotomy were more likely to have been attended by staff physicians (OR = 1.88; 95%CI: 1.01 - 3.48, to have required forceps (OR = 12.31; 95%CI: 4.9 - 30.1 and to have occurred in primiparas (OR = 4.24; 95%CI: 2.61 - 6.89. The likelihood of a nurse having attended the delivery with episiotomy was significantly lower (OR = 0.29; 95%CI: 0.16 - 0.55. Conclusion: episiotomy was found to be strongly associated with deliveries attended by staff physicians, with primiparity, and with instrumental delivery, and was less common in deliveries attended by nurses.

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

    Science.gov (United States)

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

  16. Factors Controlling the Distribution of Trace Metals in Macroalgae

    Institute of Scientific and Technical Information of China (English)

    王宝利; 刘丛强

    2004-01-01

    This paper presents the concentrations of trace metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) in macroalgae from five areas. Significant differences were noticed in trace metal concentration in macroalgae, and a large range of variations between the minimum and maximum concentrations of trace metals was found. Trace metals detected in macroalgae generally occur in adsorbed and absorbed forms. Environmental and biological factors jointly control the trace metal compositions and concentrations in macroalgae. The complexity and variation of these factors cause significant differences in trace metal concentrations in macroalgae. Environmental factors play a more important role in controlling trace metal compositions and concentrations when external available trace metals are beyond requirement for algal metabolism and growth, especially for non-essential trace metals; however, when the external available trace metals just satisfy the needs of algal metabolism and growth, biological factors would play a more important role, especially for essential trace metals. Interactions among the trace metals can also influence their compositions and concentrations in macroalgae. It is also discussed how to make macroalgae as an excellent biomonitor for trace metals.

  17. A cross-sectional study examining the prevalence and risk factors for anti-microbial-resistant generic Escherichia coli in domestic dogs that frequent dog parks in three cities in south-western Ontario, Canada.

    Science.gov (United States)

    Procter, T D; Pearl, D L; Finley, R L; Leonard, E K; Janecko, N; Reid-Smith, R J; Weese, J S; Peregrine, A S; Sargeant, J M

    2014-06-01

    Anti-microbial resistance can threaten health by limiting treatment options and increasing the risk of hospitalization and severity of infection. Companion animals can shed anti-microbial-resistant bacteria that may result in the exposure of other dogs and humans to anti-microbial-resistant genes. The prevalence of anti-microbial-resistant generic Escherichia coli in the faeces of dogs that visited dog parks in south-western Ontario was examined and risk factors for shedding anti-microbial-resistant generic E. coli identified. From May to August 2009, canine faecal samples were collected at ten dog parks in three cities in south-western Ontario, Canada. Owners completed a questionnaire related to pet characteristics and management factors including recent treatment with antibiotics. Faecal samples were collected from 251 dogs, and 189 surveys were completed. Generic E. coli was isolated from 237 of the faecal samples, and up to three isolates per sample were tested for anti-microbial susceptibility. Eighty-nine percent of isolates were pan-susceptible; 82.3% of dogs shed isolates that were pan-susceptible. Multiclass resistance was detected in 7.2% of the isolates from 10.1% of the dogs. Based on multilevel multivariable logistic regression, a risk factor for the shedding of generic E. coli resistant to ampicillin was attending dog day care. Risk factors for the shedding of E. coli resistant to at least one anti-microbial included attending dog day care and being a large mixed breed dog, whereas consumption of commercial dry and home cooked diets was protective factor. In a multilevel multivariable model for the shedding of multiclass-resistant E. coli, exposure to compost and being a large mixed breed dog were risk factors, while consumption of a commercial dry diet was a sparing factor. Pet dogs are a potential reservoir of anti-microbial-resistant generic E. coli; some dog characteristics and management factors are associated with the prevalence of anti-microbial

  18. Electricity production by a microbial fuel cell fueled by brewery wastewater and the factors in its membrane deterioration

    Institute of Scientific and Technical Information of China (English)

    Afşin Y. Çetinkaya; Emre Oğuz Köroğlu; Neslihan Manav Demir; Derya Yılmaz Baysoy; Bestamin Özkaya; Mehmet Çakmakçı

    2015-01-01

    Electricity production from brewery wastewater using dual-chamber microbial fuel cells (MFCs) with a tin-coated copper mesh in the anode was investigated by changing the hydraulic retention time (HRT). The MFCs were fed with wastewater samples from the inlet (inflow, MFC-1) and outlet (outflow, MFC-2) of an anaerobic digester of a brewery wastewater treatment plant. Both chemical oxygen demand removal and current density were improved by decreasing HRT. The best MFC performance was with an HRT of 0.5 d. The maximum power densities of 8.001 and 1.843 µW/cm2 were obtained from reactors MFC-1 and MFC-2, respectively. Microbial diversity at different condi-tions was studied using PCR-DGGE profiling of 16S rRNA fragments of the microorganisms from the biofilm on the anode electrode. The MFC reactor had mainlyGeobacter,Shewanella, andClostridium species, and some bacteria were easily washed out at lower HRTs. The fouling characteristics of the MFC Nafion membrane and the resulting degradation of MFC performance were examined. The ion exchange capacity, conductivity, and diffusivity of the membrane decreased significantly after foul-ing. The morphology of the Nafion membrane and MFC degradation were studied using scanning electron microscopy and attenuated total reflection-Fourier transform infrared spectroscopy.

  19. Understanding disease control: influence of epidemiological and economic factors

    CERN Document Server

    Oles, Katarzyna; Kleczkowski, Adam

    2011-01-01

    We present a local spread model of disease transmission on a regular network and compare different control options ranging from treating the whole population to local control in a well-defined neighborhood of an infectious individual. Comparison is based on a total cost of epidemic, including cost of palliative treatment of ill individuals and preventive cost aimed at vaccination or culling of susceptible individuals. Disease is characterized by pre- symptomatic phase which makes detection and control difficult. Three general strategies emerge, global preventive treatment, local treatment within a neighborhood of certain size and only palliative treatment with no prevention. The choice between the strategies depends on relative costs of palliative and preventive treatment. The details of the local strategy and in particular the size of the optimal treatment neighborhood weakly depends on disease infectivity but strongly depends on other epidemiological factors. The required extend of prevention is proportiona...

  20. Mineral solubility and free energy controls on microbial reaction kinetics: Application to contaminant transport in the subsurface

    Energy Technology Data Exchange (ETDEWEB)

    Taillefert, Martial [Georgia Inst. of Technology, Atlanta, GA (United States); Van Cappellen, Philippe [Univ. of Waterloo, ON (Canada)

    2016-11-14

    Recent developments in the theoretical treatment of geomicrobial reaction processes have resulted in the formulation of kinetic models that directly link the rates of microbial respiration and growth to the corresponding thermodynamic driving forces. The overall objective of this project was to verify and calibrate these kinetic models for the microbial reduction of uranium(VI) in geochemical conditions that mimic as much as possible field conditions. The approach combined modeling of bacterial processes using new bioenergetic rate laws, laboratory experiments to determine the bioavailability of uranium during uranium bioreduction, evaluation of microbial growth yield under energy-limited conditions using bioreactor experiments, competition experiments between metabolic processes in environmentally relevant conditions, and model applications at the field scale. The new kinetic descriptions of microbial U(VI) and Fe(III) reduction should replace those currently used in reactive transport models that couple catabolic energy generation and growth of microbial populations to the rates of biogeochemical redox processes. The above work was carried out in collaboration between the groups of Taillefert (batch reactor experiments and reaction modeling) at Georgia Tech and Van Cappellen (retentostat experiments and reactive transport modeling) at University of Waterloo (Canada).

  1. Cooperative research for human factors review of advanced control rooms

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung Woon; Park, Jae Chang; Lee, Yong Hee; Oh, In Seok; Lee, Hyun Chul

    2000-12-01

    This project has been performed as cooperative research between KAERI and USNRC. Human factors issues related to soft controls, which is one of key features of advanced HSI, are identified in this project. The issues are analyzed for the evaluation approaches in either experimental or analytical ways. Also, issues requiring additional researches for the evaluation of advanced HSI are identified in the areas of advanced information systems design, computer-based procedure systems, soft controls, human systems interface and plant modernization process, and maintainability of digital systems. The issues are analyzed to discriminate the urgency of researches on it to high, medium, and low levels in consideration of advanced HSI development status in Korea, and some of the issues that can be handled by experimental researches are identified. Additionally, an experimental study is performed to compare operator's performance on human error detection in advanced control rooms vs. in conventional control rooms. It is found that advanced control rooms have several design characteristics hindering operator's error detection performance compared to conventional control rooms.

  2. The factors controlling species density in herbaceous plant communities: An assessment

    Science.gov (United States)

    Grace, J.B.

    1999-01-01

    This paper evaluates both the ideas and empirical evidence pertaining to the control of species density in herbaceous plant communities. While most theoretical discussions of species density have emphasized the importance of habitat productivity and disturbance regimes, many other factors (e.g. species pools, plant litter accumulation, plant morphology) have been proposed to be important. A review of literature presenting observations on the density of species in small plots (in the vicinity of a few square meters or less), as well as experimental studies, suggests several generalizations: (1) Available data are consistent with an underlying unimodal relationship between species density and total community biomass. While variance in species density is often poorly explained by predictor variables, there is strong evidence that high levels of community biomass are antagonistic to high species density. (2) Community biomass is just one of several factors affecting variations in species density. Multivariate analyses typically explain more than twice as much variance in species density as can be explained by community biomass alone. (3) Disturbance has important and sometimes complex effects on species density. In general, the evidence is consistent with the intermediate disturbance hypothesis but exceptions exist and effects can be complex. (4) Gradients in the species pool can have important influences on patterns of species density. Evidence is mounting that a considerable amount of the observed variability in species density within a landscape or region may result from environmental effects on the species pool. (5) Several additional factors deserve greater consideration, including time lags, species composition, plant morphology, plant density and soil microbial effects. Based on the available evidence, a conceptual model of the primary factors controlling species density is presented here. This model suggests that species density is controlled by the effects of

  3. A biophysical index for predicting hydration-mediated microbial diversity in soils

    Science.gov (United States)

    Wang, G.; Or, D.

    2012-04-01

    Exploring the origins of soil microbial diversity represents an immense and uncharted scientific frontier. Progress in resolving mechanisms that promote and sustain the unparalleled soil microbial diversity found in soil requires development of process-based predictive tools that consider dynamic biophysical interactions at highly resolved spatial and temporal scales. We report a novel biophysical metric for hydration-mediated microbial coexistence in soils by integrating key biophysical variables, such as aquatic habitat size and connectivity, nutrient diffusion affecting microbial growth, and aqueous films controlling motility and dispersal, into a predictive index. Results show a surprisingly narrow range of hydration conditions (a few kPa) that mark a sharp transition from suppression (wet) to promotion (dry) of microbial diversity in unsaturated soils in agreement with limited observations and with simulation results based on individual-based models of competing populations. The framework enables systematic hypothesis testing for key factors that regulate microbial populations and affect soil bio-geochemical functions, and represents a step towards deciphering key mechanisms that support soil microbial diversity. New insights into the different roles of biophysical mechanisms in promoting soil microbial diversity enable predictions concerning microbial consortia function and bioremediation activities in soils, and may shape how we quantify microbial diversity within the context of land resources and biogeochemical cycling.

  4. Gelatin methacrylate microspheres for controlled growth factor release.

    Science.gov (United States)

    Nguyen, Anh H; McKinney, Jay; Miller, Tobias; Bongiorno, Tom; McDevitt, Todd C

    2015-02-01

    Gelatin has been commonly used as a delivery vehicle for various biomolecules for tissue engineering and regenerative medicine applications due to its simple fabrication methods, inherent electrostatic binding properties, and proteolytic degradability. Compared to traditional chemical cross-linking methods, such as the use of glutaraldehyde (GA), methacrylate modification of gelatin offers an alternative method to better control the extent of hydrogel cross-linking. Here we examined the physical properties and growth factor delivery of gelatin methacrylate (GMA) microparticles (MPs) formulated with a wide range of different cross-linking densities (15-90%). Less methacrylated MPs had decreased elastic moduli and larger mesh sizes compared to GA MPs, with increasing methacrylation correlating to greater moduli and smaller mesh sizes. As expected, an inverse correlation between microparticle cross-linking density and degradation was observed, with the lowest cross-linked GMA MPs degrading at the fastest rate, comparable to GA MPs. Interestingly, GMA MPs at lower cross-linking densities could be loaded with up to a 10-fold higher relative amount of growth factor than conventional GA cross-linked MPs, despite the GA MPs having an order of magnitude greater gelatin content. Moreover, a reduced GMA cross-linking density resulted in more complete release of bone morphogenic protein 4 and basic fibroblast growth factor and accelerated release rate with collagenase treatment. These studies demonstrate that GMA MPs provide a more flexible platform for growth factor delivery by enhancing the relative binding capacity and permitting proteolytic degradation tunability, thereby offering a more potent controlled release system for growth factor delivery.

  5. Based on Multi-Factors Grey Prediction Control for Elevator Velocity Modulation

    OpenAIRE

    2012-01-01

    This paper uses the double-factors grey prediction and the fuzzy controller for the elevator car speed control. We introduce double-factors grey control to predict car vibration for elevator speed during the operation. Simulation results show that based on multi-factors gray prediction fuzzy PI control for elevator velocity modulation system closer than simple gray fuzzy PI control elevator speed control system to the actual operation. The control effect of double factors grey fuzzy PI contro...

  6. Abiotic and Microbiotic Factors Controlling Biofilm Formation by Thermophilic Sporeformers

    NARCIS (Netherlands)

    Zhao, Y.; Caspers, M.P.M.; Metselaar, K.I.; Boer, P. de; Roeselers, G.; Moezelaar, R.; Groot, M.N.; Montijn, R.C.; Abee, T.; Korta, R.

    2013-01-01

    One of the major concerns in the production of dairy concentrates is the risk of contamination by heat-resistant spores from thermophilic bacteria. In order to acquire more insight in the composition of microbial communities occurring in the dairy concentrate industry, a bar-coded 16S amplicon seque

  7. Biological stability of drinking water: Controlling factors, methods, and challenges

    NARCIS (Netherlands)

    Prest, E.I.E.D.; Hammes, F.; Van Loosdrecht, M.C.M.; Vrouwenvelder, J.S.

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and ca

  8. Biological stability of drinking water: Controlling factors, methods, and challenges

    NARCIS (Netherlands)

    Prest, E.I.E.D.; Hammes, F.; Van Loosdrecht, M.C.M.; Vrouwenvelder, J.S.

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and ca

  9. Abiotic and microbiotic factors controlling biofilm formation by thermophilic sporeformers

    NARCIS (Netherlands)

    Zhao, Y.; Caspers, M.P.M.; Metselaar, K.I.; Boer, de P.; Roeselers, G.; Moezelaar, R.; Nierop Groot, M.N.; Montijn, R.C.; Abee, T.; Kort, R.

    2013-01-01

    One of the major concerns in the production of dairy concentrates is the risk of contamination by heat-resistant spores from thermophilic bacteria. In order to acquire more insight in the composition of microbial communities occurring in the dairy concentrate industry, a bar-coded 16S amplicon seque

  10. Biological stability of drinking water: Controlling factors, methods, and challenges

    NARCIS (Netherlands)

    Prest, E.I.E.D.; Hammes, F.; Van Loosdrecht, M.C.M.; Vrouwenvelder, J.S.

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and

  11. Risk Factors For Ectopic Pregnancy : A Case Control Study

    Directory of Open Access Journals (Sweden)

    Deshmukh J.S

    1999-01-01

    Full Text Available Research question: Which are the risk factors for ectopic pregnancy . Objective: To study the strength of association between hypothesised risk factors and ectopic pregnancy. Study design: Unmatched case- control study. Setting: Government Medical College, Hospital, Nagpur. Participants: 133 cases of ectopic pregnancy and equal number of controls (non pregnant women admitted to study hospital. Study variables : Pelvic inflammatory diseases, sexually transmitted diseases, IUD use at conception , past use of IUD, prior ectopic pregnancy, OC pills use at the time of conception, past use of OC pills, induced abortion, spontaneous abortion, infertility and pelvic and abdominal surgery. Statistical analysis: Odds ratios & their 95% CI, Pearson’s chi square test, unconditional logistic regression analysis and population attributable risk proportion. Results : Use of IUD at conception, prior ectopic pregnancy , pelvic inflammatory disease, sexually transmitted diseases, infertility, OC pills use at the time of conception, past use of IUD and induced abortion were found to be significantly associated with ectopic pregnancy. Conclusion: Identification of these risk factors for etopic pregnancy shall help in early detection and appropriate management in an individual case and it may help in devising a comprehensive preventive strategy for ectopic pregnancy

  12. Social and cultural factors in the successful control of tuberculosis.

    Science.gov (United States)

    Rubel, A J; Garro, L C

    1992-01-01

    The burden of tuberculosis on the public health is staggering. Worldwide, annual incidence of new cases is estimated to be about 8 million. Almost 3 million deaths occur yearly. Early case identification and adherence to treatment regimens are the remaining barriers to successful control. In many nations, however, fewer than half those with active disease receive a diagnosis, and fewer than half those beginning treatment complete it. The twin problems of delay in seeking treatment and abandonment of a prescribed regimen derive from complex factors. People's confusion as to the implications of the tuberculosis symptoms, costs of transportation to clinic services, the social stigma that attaches to tuberculosis, the high cost of medication, organizational problems in providing adequate followup services, and patients' perception of clinic facilities as inhospitable all contribute to the complexity. Sociocultural factors are emphasized in this report because hitherto they have not been adequately explored. Salient among those sociocultural factors is the health culture of the patients. That is, the understanding and information people have from family, friends, and neighbors as to the nature of a health problem, its cause, and its implications. A knowledge of the health culture of their patients has become a critical tool if tuberculosis control programs are to be successful. Several anthropological procedures are recommended to help uncover the health culture of people served by tuberculosis clinics.

  13. Papel del factor tumoral en el control de las reservas grasas y la obesidad.

    OpenAIRE

    M Bullo Bonet; P Garcia-Lorda; JM Argilés; J Salas Salvado

    2000-01-01

    Papel del factor tumoral en el control de las reservas grasas y la obesidad. The role of tumor necrosis factor in the control of fat reserve and obesity. Papel del factor tumoral en el control de las reservas grasas y la obesidad. The role of tumor necrosis factor in the control of fat reserve and obesity.

  14. Non-target effects of the microbial control agents Pseudomonas fluorescens DR54 and Clonostachys rosea IK726 in soils cropped with barley followed by sugar beet

    DEFF Research Database (Denmark)

    Johansen, Anders; Knudsen, Inge M.B.; Binnerup, Svend J.

    2005-01-01

    on plant growth or soil microorganisms. Phospholipid fatty acid (PLFA) analysis detected the perturbations of the soil microbial community structure in the MCA treatments as well as the return to non- perturbed conditions reflecting the decline of inoculant populations. The PLFA technique appears......Non-target effects of a bacterial (Pseudomonas fluorescens DR54) and a fungal (Clonostachys rosea IK726) microbial control agent (MCA), on the indigenous microbiota in bulk soil and rhizosphere of barley, and subsequent a sugar beet crop, were studied in a greenhouse experiment. MCAs were...... introduced by seed and soil inoculation. Bulk and rhizosphere soils were sampled regularly during the growth of barley and sugar beet. The soils were assayed for the fate of MCAs and various features of the indigenous soil microbiota. At the end of the experiment (193 d), DR54 and IK726 had declined...

  15. Factors affecting microbial spoilage and shelf-life of chilled vacuum-packed lamb transported to distant markets: a review.

    Science.gov (United States)

    Mills, John; Donnison, Andrea; Brightwell, Gale

    2014-09-01

    Vacuum-packaging and stringent control of storage temperatures enable the export of meat to distant markets, supplying a chilled product that can favourably compete with local fresh meats. To save fuel and reduce emissions, the speed of ships travelling to international markets has decreased resulting in requirement for the shelf-life of chilled lamb to be extended beyond the recognised time of 60-70 days. Growth of microorganisms and ability to cause spoilage of vacuum-packed lamb are dependent on many factors, including the type and initial concentration of spoilage bacteria, meat pH, water activity, availability of substrates, oxygen availability and, most importantly, storage time and temperature of the packaged product. This paper reviews the existing knowledge of the spoilage bacteria affecting vacuum-packed lamb, discusses the impact of these bacteria on product quality, shelf-life and spoilage, and concludes that under specified conditions the shelf-life of chilled lamb can be extended to beyond 70 days.

  16. Frequency control system based on power factor control of asynchronous motor

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-chun; YANG Fei-xia; REN Zhi-ling

    2005-01-01

    Deduced the relationship between the power factor (PF) and the angular frequency according to the simplified equivalent circuit of asynchronous motor, forming a power factor auto-control system. An anti-interference circuit was also introduced in the middle voltage link of inverter to avoid the shift of the optimum PF point caused by the change of the load and the reliable run of the control system was assured. The experiment results show that it has a good self-adaptation in the whole scope of speed adjustment and an obvious economization on energy while it runs under load.

  17. Shoreline as a controlling factor in commercial shrimp production

    Science.gov (United States)

    Faller, K. H. (Principal Investigator)

    1979-01-01

    The author has identified the following significant results. An ecological model was developed that relates marsh detritus export and shrimp production. It was based on the hypothesis that the shoreline is a controlling factor in the production of shrimp through regulation of detritus export from the marsh. LANDSAT data were used to develop measurement of shoreline length and areas of marsh having more than 5.0 kilometers of shoreline per square kilometer of area for the Louisiana coast, demonstrating the capability of remote sensing to provide important geographic information. These factors were combined with published tidal ranges and salinities to develop a mathematical model that predicted shrimp production for nine geographic units of the Louisiana coast, as indicated by the long term average commercial shrimp yield.

  18. Revisiting factors controlling methane emissions from high-Arctic tundra

    DEFF Research Database (Denmark)

    Mastepanov, M.; Sigsgaard, C.; Tagesson, T.;

    2013-01-01

    with measurements made outside the growing season, are underrepresented in the literature. Here we present results of 5 yr (2006-2010) of automatic chamber measurements at a high-Arctic location in Zackenberg, NE Greenland, covering both the growing seasons and two months of the following freeze-in periods...... explained by high seasonality of both variables, and weakly correlated with the water table. The greatest variability in fluxes between the study years was observed during the first part of the growing season. Somewhat surprisingly, this variability could not be explained by commonly known factors...... controlling methane emission, i.e. temperature and water table position. Late in the growing season CH4 emissions were found to be very similar between the study years (except the extremely dry 2010) despite large differences in climatic factors (temperature and water table). Late-season bursts of CH4...

  19. Multiple Sclerosis Associated Risk Factors: A Case-Control Study

    Directory of Open Access Journals (Sweden)

    Jalal POOROLAJAL

    2015-11-01

    Full Text Available Background: Hamadan Province is one of the high-risk regions in Iran for Multiple sclerosis (MS. A majority of the epidemiological studies conducted in Iran addressing MS are descriptive. This study was conducted to assess MS and its associated risk factors in Hamadan Province, the west of Iran.Methods: This case-control study compared 100 patients with MS (case group and 100 patients with acute infectious diseases (control group from September 2013 to March 2014. A checklist was used to assess the demographic, medical, and family history of the patients. The Friedman-Rosenman questionnaire was also used to assess personality type. Statistical analysis was performed using logistic regression model with Stata 11 software program.Results: The adjusted odds ratio (OR estimate of MS was 4.37 (95% CI: 2.33, 8.20 for females compared to males; 0.15 (95% CI: 0.06, 0.43 for people aged above 50 years compared to aged 14 to 29 years; 0.44 (95% CI: 0.21, 0.91 for overweight or obese people compared to normal weights. Crude OR indicated a significant association between the occurrence of MS and exclusive breast feeding, season of birth, and smoking. However, the association was not statistically significant after adjustment for other covariates.Conclusion: The risk of MS is significantly lower in male gender, obese/overweight, and old people. Furthermore, non-smoking, non-exclusive breast-feeding, and born in autumn may increase the risk of MS but need further investigation. However, long-term large prospective cohort studies are needed to investigate the true effect of the potential risk factors on MS. Keywords: Multiple sclerosis, Risk factors, Case-control study, Iran

  20. Three controllable factors of steady operation of EGSB reactor

    Institute of Scientific and Technical Information of China (English)

    LI Hui-li; LU Bing-nan; LI Fang

    2008-01-01

    The bench- scale EGSB (expanded granular sludge bed) reactor was operated to study the effect of sludge loading rate, pH value and nutrient element on the operation of the EGSB reactor and the control rule of these factors. Continuous flow was used to treat synthetic wastewater containing dextrose and beer, and the temperature of reactor was controlled at mesophiles temperature (33 ℃). The experimental results demonstrated trolled by adding sodium bicarbonate, the proper additive quantity was 1000-1200 mg/L; the additive quantity wastewater with 400-5000 mg/L COD concentration. The COD removal efficiency was over 85%. The operation of the EGSB reactor was steady and the EGSB reactor had strong anti-shock load ability.

  1. Factors Associated with Academic Achievement in Children with Controlled Epilepsy.

    Science.gov (United States)

    Williams, Jane; Phillips, Tonya; Griebel, May L.; Sharp, Gregory B.; Lange, Bernadette; Edgar, Terence; Simpson, Pippa

    2001-06-01

    Children with epilepsy are at risk for academic underachievement. Multiple etiologies for this academic vulnerability have been suggested by past research including lower self-esteem, inattention, memory inefficiency, and lower socioeconomic status. The present study assessed 65 children (mean age = 10 years, 5 months) with well-controlled epilepsy on the four primary factors, as well as academic achievement and intelligence. A stepwise regression analysis was employed with academic achievement as the dependent variable and measures of self-esteem, attention, memory, and socioeconomic status as independent variables. When intelligence was controlled, attention was the only variable associated with achievement scores. Seizure variables including seizure type and duration of epilepsy were not associated with differences in academic performance. Findings support the importance of measuring attention skills in children with epilepsy and suggest that reduced auditory attention skills may be associated with decreased academic performance in these children.

  2. Microbially induced carbonate precipitation (MICP) by denitrification as ground improvement method - Process control in sand column experiments

    Science.gov (United States)

    Pham, Vinh; van Paassen, Leon; Nakano, Akiko; Kanayama, Motohei; Heimovaara, Timo

    2013-04-01

    Calcite precipitation induced by microbes has been proven to be efficient in stabilizing granular soils, especially with urea hydrolysis, as it has been successfully demonstrated in a pilot application 2010. However, as a byproduct highly concentrated ammonium chloride (NH4Cl) solution is produced, which has to be removed and disposed and forms a significant disadvantage of the technique that makes an alternative process like denitrification preferred. The proof of principle of microbially induced calcite precipitation (MICP) by denitrification has been demonstrated by Van Paassen et al (2010) who suggested that instead of producing waste as a byproduct, different pre-treated waste streams could be used as substrates for in situ growth of denitrifying bacteria and simultaneous cementation without producing waste to be removed. In this study sand column experiments are performed in which calcium carbonate was successfully precipitated by indigenous denitrifying micro-organisms, which were supplied weekly with a pulse of a substrate solution containing calcium acetate and calcium nitrate. Besides the production of calcite and the growth of bacteria in biofilms, the reduction of nitrate resulted in the production of (nitrogen) gas. It was observed that this gas partly fills up the pore space and consequently contributed to a reduction of the permeability of the treated sand. The presence of gas in the pore space affected the flow of the injected substrates and influenced to the distribution of calcium carbonate. The effect of the mean particle size (D50) on the flow and transport of solutes and gas in the porous media has been evaluated by treating several columns with varying grain size distribution and comparing the change in permeability after each incubation period and analyzing the distribution of the gas throughout the columns using X-ray computed tomography (CT) scanning. The present results show that there is a considerable decrease of permeability - a

  3. Identification of controlling factors for the initiation of corrosion of fresh concrete sewers.

    Science.gov (United States)

    Jiang, Guangming; Sun, Xiaoyan; Keller, Jurg; Bond, Philip L

    2015-09-01

    The development of concrete corrosion in new sewer pipes undergoes an initiation process before reaching an active corrosion stage. This initiation period is assumed to last several months to years but the key factors affecting the process, and its duration, are not well understood. This study is therefore focused on this initial stage of the corrosion process and the effect of key environmental factors. Such knowledge is important for the effective management of corrosion in new sewers, as every year of life extension of such systems has a very high financial benefit. This long-term (4.5 year) study has been conducted in purpose-built corrosion chambers that closely simulated the sewer environment, but with control of three key environmental factors being hydrogen sulfide (H2S) gas phase concentration, relative humidity and air temperature. Fresh concrete coupons, cut from an industry-standard sewer pipe, were exposed to the corrosive conditions in the chambers, both in the gas phase and partially submerged in wastewater. A total of 36 exposure conditions were investigated to determine the controlling factors by regular retrieval of concrete coupons for detailed analysis of surface pH, sulfur compounds (elemental sulfur and sulfate) and concrete mass loss. Corrosion initiation times were thus determined for different exposure conditions. It was found that the corrosion initiation time of both gas-phase and partially-submerged coupons was positively correlated with the gas phase H2S concentration, but only at levels of 10 ppm or below, indicating that sulfide oxidation rate rather than the H2S concentration was the limiting factor during the initiation stage. Relative humidity also played a role for the corrosion initiation of the gas-phase coupons. However, the partially-submerged coupons were not affected by humidity as these coupons were in direct contact with the sewage and hence did have sufficient moisture to enable the microbial processes to proceed. The

  4. Control of Escherichia coli and Listeria monocytogenes in suckling-lamb meat evaluated using microbial challenge tests

    NARCIS (Netherlands)

    Osés, S.M.; Diez, A.M.; Gómez, E.M.; Wilches-Pérez, D.; Luning, P.A.; Jaime, I.; Rovira, J.

    2015-01-01

    Escherichia coli and Listeria monocytogenes microbial challenge tests were performed on fresh suckling-lamb meat. Hind leg slices were chilly stored under two modified atmosphere packaging (MAP) environments (A: 15%O2/60%CO2/25%N2, B: 15%O2/30%CO2/55%N2) and vacuum packaging (V). Only E. coli was re

  5. An Evolutionarily Conserved Plant RKD Factor Controls Germ Cell Differentiation.

    Science.gov (United States)

    Koi, Satoshi; Hisanaga, Tetsuya; Sato, Katsutoshi; Shimamura, Masaki; Yamato, Katsuyuki T; Ishizaki, Kimitsune; Kohchi, Takayuki; Nakajima, Keiji

    2016-07-11

    In contrast to animals, in which the germ cell lineage is established during embryogenesis, plant germ cells are generated in reproductive organs via reprogramming of somatic cells. The factors that control germ cell differentiation and reprogramming in plants are poorly understood. Members of the RKD subfamily of plant-specific RWP-RK transcription factors have been implicated in egg cell formation in Arabidopsis based on their expression patterns and ability to cause an egg-like transcriptome upon ectopic expression [1]; however, genetic evidence of their involvement is lacking, due to possible genetic redundancy, haploid lethality, and the technical difficulty of analyzing egg cell differentiation in angiosperms. Here we analyzed the factors that govern germ cell formation in the liverwort Marchantia polymorpha. This recently revived model bryophyte has several characteristics that make it ideal for studies of germ cell formation, such as low levels of genetic redundancy, readily accessible germ cells, and the ability to propagate asexually via gemma formation [2, 3]. Our analyses revealed that MpRKD, a single RWP-RK factor closely related to angiosperm RKDs, is preferentially expressed in developing eggs and sperm precursors in M. polymorpha. Targeted disruption of MpRKD had no effect on the gross morphology of the vegetative and reproductive organs but led to striking defects in egg and sperm cell differentiation, demonstrating that MpRKD is an essential regulator of germ cell differentiation. Together with previous findings [1, 4-6], our results suggest that RKD factors are evolutionarily conserved regulators of germ cell differentiation in land plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Understanding disease control: influence of epidemiological and economic factors.

    Directory of Open Access Journals (Sweden)

    Katarzyna Oleś

    Full Text Available We present a model of disease transmission on a regular and small world network and compare different control options. Comparison is based on a total cost of epidemic, including cost of palliative treatment of ill individuals and preventive cost aimed at vaccination or culling of susceptible individuals. Disease is characterized by pre-symptomatic phase, which makes detection and control difficult. Three general strategies emerge: global preventive treatment, local treatment within a neighborhood of certain size and only palliative treatment with no prevention. While the choice between the strategies depends on a relative cost of palliative and preventive treatment, the details of the local strategy and, in particular, the size of the optimal treatment neighborhood depend on the epidemiological factors. The required extent of prevention is proportional to the size of the infection neighborhood, but depends on time till detection and time till treatment in a non-nonlinear (power law. The optimal size of control neighborhood is also highly sensitive to the relative cost, particularly for inefficient detection and control application. These results have important consequences for design of prevention strategies aiming at emerging diseases for which parameters are not nessecerly known in advance.

  7. A coupled molecular and field-based approach to study microbial controls on methane flux in upland soils

    Science.gov (United States)

    Judd, C. R.; von Fischer, J. C.; Fierer, N.

    2007-12-01

    Predicting the responses of ecosystems to global change depends, in part, on understanding how soil microbial communities respond to external controls. To address this question, we are studying a relatively simple biogeochemical process: methane consumption in upland (i.e., well-drained, oxic) soils. In this process, methane molecules diffuse from the atmosphere into the soil, where they are consumed by methanotrophic bacteria. Because of the simplicity of this process, we have been able to develop a reaction-diffusion model that allows us to directly quantify methanotroph activity in situ from chamber-based measures of flux and diffusivity. Moreover, because the bacteria that oxidize methane come from a phylogenetically cohesive group, we can use molecular tools to quantify the size of methanotroph community and determine its species composition. Our application of these approaches on the Shortgrass Steppe Long-Term Ecological Research (SGS LTER) site in northeastern Colorado has revealed strong temporal and spatial patterns in methane uptake rates that are driven primarily by methanotroph activity, and very little by soil diffusivity. The temporal patterns in methanotroph activity follow seasonal changes in soil temperature and water content, with sharp reductions in activity associated with hot, dry conditions. Spatial patterns in activity follow differences in soil texture, with sandier soils expressing a greater range of methanotroph activity than clay soils. Although methanotroph abundances did not vary across soil types, the phylogenetic structure of the methanotroph communities differed significantly between clay and sand soil types. In addition, we found that the majority of methanotrophs were not the usual Type I or Type II, but instead were of the JR2 and JR3 types previously found only in a dry California grassland by Horz et al. AEM (2005). Together, these observations suggest that the species composition of methanotroph communities reflects changes in

  8. Biotechnological Aspects of Microbial Extracellular Electron Transfer

    Science.gov (United States)

    Kato, Souichiro

    2015-01-01

    Extracellular electron transfer (EET) is a type of microbial respiration that enables electron transfer between microbial cells and extracellular solid materials, including naturally-occurring metal compounds and artificial electrodes. Microorganisms harboring EET abilities have received considerable attention for their various biotechnological applications, in addition to their contribution to global energy and material cycles. In this review, current knowledge on microbial EET and its application to diverse biotechnologies, including the bioremediation of toxic metals, recovery of useful metals, biocorrosion, and microbial electrochemical systems (microbial fuel cells and microbial electrosynthesis), were introduced. Two potential biotechnologies based on microbial EET, namely the electrochemical control of microbial metabolism and electrochemical stimulation of microbial symbiotic reactions (electric syntrophy), were also discussed. PMID:26004795

  9. Factors Controlling Sediment Denitrification Rates in Grassland and Forest Streams

    Directory of Open Access Journals (Sweden)

    Haryun Kim

    2014-01-01

    Full Text Available Sediment denitrification is an important nitrate (NO3- removal process from agricultural streams. The direct and indirect factors that control denitrification rates in tributary sediments can vary depending on the types of agricultural activities and vegetation. Our research investigated (1 tributary sediment denitrification rates in a grassland stream affected by pasture ecosystems and a forest stream affected by N fertilization; and (2 the environmental factors that determine denitrification rates in tributary sediments. The denitrification enzyme activity (DEA in grassland stream sediments is positively correlated with precipitation likely due to the increased nutrient exchange rates between stream water and sediments, and was higher than in forest stream sediments, leading to a decrease in NO3- concentration ([NO3-] in stream sediments. The DEA in riparian sediments was regulated by carbon concentrations and did not contribute to NO3- removal from the riparian sediment in grassland and forest streams. Thus, environmental factors affected by different types of agricultural activities and vegetation might regulate denitrification rates and [NO3-] in agricultural stream ecosystems.

  10. Zoom in new insights of potential microbial control of N and CH4 gaseous losses induced by different agricultural practices in temperate paddy soils

    Science.gov (United States)

    Cucu, Maria Alexandra; Bardi, Laura; Said-Pullicino, Daniel; Sacco, Dario; Celi, Luisella; Gorra, Roberta

    2016-04-01

    Rice is the world's single most important food crop and a primary food source for more than a third of the world's population. Usually, rice is grown in flooded paddies that result in anoxic soil conditions throughout a major part of the cropping period. Redox processes in wetland ecosystems combined with crop residue incorporation play an important role in element cycling and ecological functions of rice ecosystems. Microbial communities are at the basis of the functioning of wetlands and the ecosystem services they provide. Agronomic management practices adopted in rice paddies may have important effects on microbial biomass functionality and interactions, but these are largely unknown in situ. They mediate important processes such as nitrification, anaerobic ammonia oxidation (Anammox), denitrification, and methanogenesis that regulate ecosystem functioning and control greenhouse gases (GHG) emissions. Therefore, it is crucial to comprehend the microbial control of these processes as a function of different crop residue and water management practices. Here we highlight recent findings based on the exploration of microbial functional genes as biogeochemical indicators. Through both lab and field experiments and by linking to GHG emissions and soil chemistry, we evaluated niche differentiation between microbial communities and the crucial role of agronomic management in regulating their potential functionality. Recent studies showed a high abundance of both 16S communities, bacteria and archaea, confirming the high relevance of archaeal mediated processes in rice ecosystems. Our results unravel the complete denitrification as key player in regulating major nitrogen (N) fluxes in fertilized paddies. In a laboratory experiment this process was shown to be driven by both archaea and bacteria harboring nosZ gene, but especially by archaea in the absence of straw. In addition, part of the immobilized N was attributed to nitrous oxide (N2O) reducing archaea, suggesting

  11. Controllability analysis of transcriptional regulatory networks reveals circular control patterns among transcription factors

    DEFF Research Database (Denmark)

    Österlund, Tobias; Bordel, Sergio; Nielsen, Jens

    2015-01-01

    Transcriptional regulation is the most committed type of regulation in living cells where transcription factors (TFs) control the expression of their target genes and TF expression is controlled by other TFs forming complex transcriptional regulatory networks that can be highly interconnected. Here...... we analyze the topology and organization of nine transcriptional regulatory networks for E. coli, yeast, mouse and human, and we evaluate how the structure of these networks influences two of their key properties, namely controllability and stability. We calculate the controllability for each network...... as a measure of the organization and interconnectivity of the network. We find that the number of driver nodes n(D) needed to control the whole network is 64% of the TFs in the E. coli transcriptional regulatory network in contrast to only 17% for the yeast network, 4% for the mouse network and 8...

  12. Effects of operational factors on soluble microbial products in a carrier anaerobic baffled reactor treating dilute wastewater

    Institute of Scientific and Technical Information of China (English)

    FENG Huajun; HU Lifang; SHAN Dan; FANG Chengran; HE Yonghua; SHEN Dongsheng

    2008-01-01

    The effects of feed strength,hydraulic residence time(HRT),and operational temperatures on soluble microbial product(SMP) production were investigated,to gain insights into the production mechanism.A carrier anaerobic batfled reactor (CABR) treating dilute wastewater was operated under a wide range of operational conditions,namely,feed strengths of 300-600 mg/L,HRTs of 9-18 h,and temperatures of 10-28℃.Generally, SMP production increased with increasing feed strength and decreasing temperature.At high temperature (28℃),SMP production increased with decreasing HRT. As the temperature Was decreased to 18 and 10℃.the SMP production was at its peak for 12 h HRT Therefore,temperature could be an important determinant of SMP production along with HRT. A higher SMP to soluble chemical oxygen demand (SCOD) ratio Was found at high temperature and long HRT because of complete volatile fatty acid degradation.SMP accounted for 50%-75% of the SCOD in the last chamber of the CABR.As a secondary metabolite.some SMP could be consumed at lower feed strength.

  13. Risk factor control is key in diabetic nephropathy.

    Science.gov (United States)

    Lewis, Gareth; Maxwell, Alexander P

    2014-02-01

    Prolonged duration of diabetes, poor glycaemic control and hypertension are major risk factors for both diabetic nephropathy and cardiovascular disease. Optimising blood sugar control together with excellent control of blood pressure can reduce the risk of developing diabetic nephropathy. Diabetic nephropathy should be considered in any patient with diabetes when persistent albuminuria develops. Microalbuminuria is the earliest clinically detectable indicator of diabetic nephropathy risk. The majority of patients with diabetic nephropathy are appropriately diagnosed based on elevated urinary albumin excretion and/or reduced 0032-6518 renal function. Patients with type 2 diabetes should have annual urinary ACR measurements from the time of diabetes diagnosis while those with type 1 diabetes should commence five years after diagnosis. Blood pressure lowering to 130/80mmHg and reduction of proteinuria to diabetic nephropathy and reduces the number of cardiovascular events. Drugs that block the renin-angiotensin-aldosterone system (RAAS) are effective in reducing proteinuria, managing hypertension and reducing cardiovascular risk. Unless there are clear contraindications or intolerance all patients with diabetic nephropathy should be prescribed an ACEI or ARB. Stopping an ACEI or ARB during intercurrent illness or times of volume depletion is critically important. Patients with diabetic nephropathy should have at least yearly measurements of blood pressure, renal function and urinary ACR.

  14. Geochemical factors controlling free Cu ion concentrations in river water

    Science.gov (United States)

    Rozan, Tim F.; Benoit, Gaboury

    1999-10-01

    Copper speciation was determined monthly at seven sites on four rivers in southern New England to understand which geochemical factors control free metal ion concentrations in river water. Samples were conventionally filtered (stripping voltammetry (DPASV) was used to quantify natural organic complexation and cathodic stripping square wave voltammetry (CSSWV) to measure directly both Cu sulfide complexes and total EDTA concentrations. The results showed both dissolved organic matter (DOM) and sulfide complexation dominate Cu speciation and control the concentrations of free ion. Free Cu2+ was calculated to be in the subnanomolar range for the majority of the year. Only in the winter months, when concentrations of DOM and metal sulfides complexes were at a minimum were free metal ions directly measurable by DPASV at low nanomolar concentrations. The extent of sulfide complexation appears to be dominated by the size of headwater marshes (upstream sampling sites) and by the amount of sewage treatment plant effluent (downstream sites). DOM complexation was related to the organic matter composition and followed model organic ligands. Indirect evidence suggests variations in river water pH and Ca2+ (metal competition) has only a minor role in Cu complexation. Measured concentrations of total EDTA suggest this synthetic ligand can control Cu speciation in some highly developed watersheds; however, competition from Ni (and possibly Fe) limits the extent of this complexation.

  15. Systems Biology of Microbial Exopolysaccharides Production.

    Science.gov (United States)

    Ates, Ozlem

    2015-01-01

    Exopolysaccharides (EPSs) produced by diverse group of microbial systems are rapidly emerging as new and industrially important biomaterials. Due to their unique and complex chemical structures and many interesting physicochemical and rheological properties with novel functionality, the microbial EPSs find wide range of commercial applications in various fields of the economy such as food, feed, packaging, chemical, textile, cosmetics and pharmaceutical industry, agriculture, and medicine. EPSs are mainly associated with high-value applications, and they have received considerable research attention over recent decades with their biocompatibility, biodegradability, and both environmental and human compatibility. However, only a few microbial EPSs have achieved to be used commercially due to their high production costs. The emerging need to overcome economic hurdles and the increasing significance of microbial EPSs in industrial and medical biotechnology call for the elucidation of the interrelations between metabolic pathways and EPS biosynthesis mechanism in order to control and hence enhance its microbial productivity. Moreover, a better understanding of biosynthesis mechanism is a significant issue for improvement of product quality and properties and also for the design of novel strains. Therefore, a systems-based approach constitutes an important step toward understanding the interplay between metabolism and EPS biosynthesis and further enhances its metabolic performance for industrial application. In this review, primarily the microbial EPSs, their biosynthesis mechanism, and important factors for their production will be discussed. After this brief introduction, recent literature on the application of omics technologies and systems biology tools for the improvement of production yields will be critically evaluated. Special focus will be given to EPSs with high market value such as xanthan, levan, pullulan, and dextran.

  16. Systems biology of microbial exopolysaccharides production

    Directory of Open Access Journals (Sweden)

    Ozlem eAtes

    2015-12-01

    Full Text Available Exopolysaccharides (EPS produced by diverse group of microbial systems are rapidly emerging as new and industrially important biomaterials. Due to their unique and complex chemical structures and many interesting physicochemical and rheological properties with novel functionality, the microbial EPSs find wide range of commercial applications in various fields of the economy such as food, feed, packaging, chemical, textile, cosmetics and pharmaceutical industry, agriculture and medicine. EPSs are mainly associated with high-value applications and they have received considerable research attention over recent decades with their biocompatibility, biodegradability, and both environmental and human compatibility. However only a few microbial EPSs have achieved to be used commercially due to their high production costs. The emerging need to overcome economic hurdles and the increasing significance of microbial EPSs in industrial and medical biotechnology call for the elucidation of the interrelations between metabolic pathways and EPS biosynthesis mechanism in order to control and hence enhance its microbial productivity. Moreover a better understanding of biosynthesis mechanism is a significant issue for improvement of product quality and properties and also for the design of novel strains. Therefore a systems-based approach constitutes an important step towards understanding the interplay between metabolism and EPS biosynthesis and further enhances its metabolic performance for industrial application. In this review, primarily the microbial EPSs, their biosynthesis mechanism and important factors for their production will be discussed. After this brief introduction, recent literature on the application of omics technologies and systems biology tools for the improvement of production yields will be critically evaluated. Special focus will be given to EPSs with high market value such as xanthan, levan, pullulan and dextran.

  17. Microbial distribution in the Environmental Control and Life Support System water recovery test conducted at NASA, MSFC

    Science.gov (United States)

    Gauthier, J. J.; Roman, M. C.; Kilgore, B. A.; Huff, T. L.; Obenhuber, D. C.; Terrell, D. W.; Wilson, M. E.; Jackson, N. E.

    1991-01-01

    NASA/MSFC is developing a physical/chemical treatment system to reclaim wastewater for reuse on Space Station Freedom (SSF). Integrated testing of hygiene and potable water subsystems assessed the capability to reclaim water to SSF specifications. The test was conducted from May through July 1990 with a total of 47 days of system test operation. Water samples were analyzed using standard cultural methods employing membrane filtration and spread plate techniques and epifluorescence microscopy. Fatty acid methyl ester and biochemical profiles were used for microbial identification. Analysis of waste and product water produced by the subsystems demonstrated the effective reduction of viable microbial populations greater than 8.0E + 06 colony forming units (CFU) per 100 mL to an average of 5 CFU/100 mL prior to distribution into storage tanks.

  18. Microbial distribution in the Environmental Control and Life Support System water recovery test conducted at NASA, MSFC

    Science.gov (United States)

    Gauthier, J. J.; Roman, M. C.; Kilgore, B. A.; Huff, T. L.; Obenhuber, D. C.; Terrell, D. W.; Wilson, M. E.; Jackson, N. E.

    1991-01-01

    NASA/MSFC is developing a physical/chemical treatment system to reclaim wastewater for reuse on Space Station Freedom (SSF). Integrated testing of hygiene and potable water subsystems assessed the capability to reclaim water to SSF specifications. The test was conducted from May through July 1990 with a total of 47 days of system test operation. Water samples were analyzed using standard cultural methods employing membrane filtration and spread plate techniques and epifluorescence microscopy. Fatty acid methyl ester and biochemical profiles were used for microbial identification. Analysis of waste and product water produced by the subsystems demonstrated the effective reduction of viable microbial populations greater than 8.0E + 06 colony forming units (CFU) per 100 mL to an average of 5 CFU/100 mL prior to distribution into storage tanks.

  19. Microbial Weathering of Olivine

    Science.gov (United States)

    McKay, D. S.; Longazo, T. G.; Wentworth, S. J.; Southam, G.

    2002-01-01

    Controlled microbial weathering of olivine experiments displays a unique style of nanoetching caused by biofilm attachment to mineral surfaces. We are investigating whether the morphology of biotic nanoetching can be used as a biosignature. Additional information is contained in the original extended abstract.

  20. Risk factors for syphilis in women: case-control study.

    Science.gov (United States)

    Macêdo, Vilma Costa de; Lira, Pedro Israel Cabral de; Frias, Paulo Germano de; Romaguera, Luciana Maria Delgado; Caires, Silvana de Fátima Ferreira; Ximenes, Ricardo Arraes de Alencar

    2017-08-17

    To determine the sociodemographic, behavioral, and health care factors related to the occurrence of syphilis in women treated at public maternity hospitals. This is a case-control study (239 cases and 322 controls) with women admitted to seven maternity hospitals in the municipality of Recife, Brazil, from July 2013 to July 2014. Eligible women were recruited after the result of the VDRL (Venereal Disease Research Laboratory) under any titration. The selection of cases and controls was based on the result of the serology for syphilis using ELISA (enzyme-linked immunosorbent assay). The independent variables were grouped into: sociodemographic, behavioral, clinical and obstetric history, and health care in prenatal care and maternity hospital. Information was obtained by interview, during hospitalization, with the application of a questionnaire. Odds ratios and 95% confidence intervals were estimated using logistic regression to identify the predicting factors of the variable to be explained. The logistic regression analysis identified as determinant factors for gestational syphilis: education level of incomplete basic education or illiterate (OR = 2.02), lack of access to telephone (OR = 2.4), catholic religion (OR = 1.70 ), four or more pregnancies (OR = 2.2), three or more sexual partners in the last year (OR = 3.1), use of illicit drugs before the age of 18 (OR = 3.0), and use of illicit drugs by the current partner (OR = 1.7). Only one to three prenatal appointments (OR = 3.5) and a previous history of sexually transmitted infection (OR = 9.7) were also identified as determinant factors. Sociodemographic, behavioral, and health care factors are associated with the occurrence of syphilis in women and should be taken into account in the elaboration of universal strategies aimed at the prevention and control of syphilis, but with a focus on situations of greater vulnerability. Determinar os fatores sociodemográficos, comportamentais e de assistência à sa

  1. Environmental and microbial factors influencing methane and nitrous oxide fluxes in Mediterranean cork oak woodlands: trees make a difference.

    Science.gov (United States)

    Shvaleva, Alla; Siljanen, Henri M P; Correia, Alexandra; Costa E Silva, Filipe; Lamprecht, Richard E; Lobo-do-Vale, Raquel; Bicho, Catarina; Fangueiro, David; Anderson, Margaret; Pereira, João S; Chaves, Maria M; Cruz, Cristina; Martikainen, Pertti J

    2015-01-01

    Cork oak woodlands (montado) are agroforestry systems distributed all over the Mediterranean basin with a very important social, economic and ecological value. A generalized cork oak decline has been occurring in the last decades jeopardizing its future sustainability. It is unknown how loss of tree cover affects microbial processes that are consuming greenhouse gases in the montado ecosystem. The study was conducted under two different conditions in the natural understory of a cork oak woodland in center Portugal: under tree canopy (UC) and open areas without trees (OA). Fluxes of methane and nitrous oxide were measured with a static chamber technique. In order to quantify methanotrophs and bacteria capable of nitrous oxide consumption, we used quantitative real-time PCR targeting the pmoA and nosZ genes encoding the subunit of particulate methane mono-oxygenase and catalytic subunit of the nitrous oxide reductase, respectively. A significant seasonal effect was found on CH4 and N2O fluxes and pmoA and nosZ gene abundance. Tree cover had no effect on methane fluxes; conversely, whereas the UC plots were net emitters of nitrous oxide, the loss of tree cover resulted in a shift in the emission pattern such that the OA plots were a net sink for nitrous oxide. In a seasonal time scale, the UC had higher gene abundance of Type I methanotrophs. Methane flux correlated negatively with abundance of Type I methanotrophs in the UC plots. Nitrous oxide flux correlated negatively with nosZ gene abundance at the OA plots in contrast to that at the UC plots. In the UC soil, soil organic matter had a positive effect on soil extracellular enzyme activities, which correlated positively with the N2O flux. Our results demonstrated that tree cover affects soil properties, key enzyme activities and abundance of microorganisms and, consequently net CH4 and N2O exchange.

  2. Environmental and microbial factors influencing methane and nitrous oxide fluxes in Mediterranean cork oak woodlands: trees make a difference

    Directory of Open Access Journals (Sweden)

    Alla eShvaleva

    2015-10-01

    Full Text Available Cork oak woodlands (montado are agroforestry systems distributed all over the Mediterranean basin with a very important social, economic and ecological value. A generalized cork oak decline has been occurring in the last decades jeopardizing its future sustainability. It is unknown how loss of tree cover affects microbial processes that are consuming greenhouse gas fluxes in the montado ecosystem. The study was conducted under two different conditions in the natural understory of a cork oak woodland in center Portugal: under tree canopy (UC and open areas without trees (OA. Fluxes of methane and nitrous oxide were measured with a static chamber technique. In order to quantify methanotrophs and bacteria capable of nitrous oxide consumption, we used quantitative real-time PCR targeting the pmoA and nosZ gene encoding the subunit of particulate methane mono-oxygenase and catalytic subunit of the nitrous oxide reductase, respectively. A significant seasonal effect was found on CH4 and N2O fluxes and pmoA and nosZ gene abundance. Tree cover had no effect on methane fluxes; conversely, whereas the UC plots were net emitters of nitrous oxide, the loss of tree cover resulted in a shift in the emission pattern such that the OA plots were a net sink for nitrous oxide. In a seasonal time scale, the UC had higher gene abundance of Type I methanotrophs. Methane flux correlated negatively with abundance of Type I methanotrophs in the UC plots. Nitrous oxide flux correlated negatively with nosZ gene abundance at the OA plots in contrast to that at the UC plots. In the UC soil, SOM had a positive effect on soil extracellular enzyme activities (EEA, which correlated positively with the N2O flux. Our results demonstrated that tree cover affects soil properties, key enzyme activities and abundance of microorganisms and, consequently net CH4 and N2O exchange.

  3. Factors Controlling Nanoparticle Pharmacokinetics: An Integrated Analysis and Perspective

    DEFF Research Database (Denmark)

    Moghimi, Seyed Moien; Hunter, A.C.; Andresen, T.L.

    2012-01-01

    of interrelated core and interfacial physicochemical and biological factors. Pertinent to realizing therapeutic goals, definitive maps that establish the interdependency of nanoparticle size, shape, and surface characteristics in relation to interfacial forces, biodistribution, controlled drug release, excretion......, and adverse effects must be outlined. These concepts are critically evaluated and an integrated perspective is provided on the basis of the recent application of nanoscience approaches to nanocarrier design and engineering. The future of this exciting field is bright; some regulatory-approved products...... are already on the market and many are in late-phase clinical trials. With concomitant advances in extensive computational knowledge of the genomics and epigenomics of interindividual variations in drug responses, the boundaries toward development of personalized nanomedicines can be pushed further....

  4. Factors Influencing Glycemic Control in Children with Type 1 Diabetes

    Directory of Open Access Journals (Sweden)

    Seher Çakır

    2010-05-01

    Full Text Available Introduction: There are a plenty of factors influencing glycemic control in children with type 1 diabetes mellitus (DM. The aim of this study was to determine the factors influencing metabolic control in children with type 1 DM. Materials and Method: The study was performed in 200 children with type 1 DM between the ages 6 months to 18 years. This study was conducted by interviewing individually with the children and their families and completing the questionnaires related to their demographic features and data associated with their illness. The laboratory findings and medical information of the patients from the charts were also retrospectively recorded. Results: There were a total of 200 patients including 104 (52% girls and 96 (48% boys. The mean age of the patients was 11.7 (±4.26 years. The mean duration of diabetes was 3.8 years (6 months to 14 years. Eighty-nine percent of all patients and all of the patients between 12 and 18 years of age were on intensive insulin therapy. Mean insulin dose was 0.84±0.19 units/kg/day. The mean HbA1c value was 8.8%. Body mass index (BMI mean z-score was -0.06±1.19. There were no correlations between HbA1c and the duration of diabetes or age although a positive correlation was found with insulin dose (r=0.27 p<0.01. It was found that intensive therapy did not lower HbA1c values or the risk of severe hypoglycemia. Nevertheless, there was a decrease in HbA1c values of 72 (36% patients whose therapy was converted from conventional therapy to intensive therapy (p<0.05. HbA1c values were found to be higher in patients who lived with more than 4 persons in the house, who were non-compliant to follow-up or diet, who had more than 3 symptomatic hypoglycemia in the last 6 months, who had episodes of diabetic ketoacidosis (DKA, who were adolescent at the time of diagnosis, and who were admitted with diabetic ketoacidosis at the time of diagnosis (p<0.05. Although there was a correlation between insulin doses and

  5. 微生物共代谢降解难降解废水影响因素的研究进展%Research on the influencing factors of the non-biodegradable wastewater treated by microbial co-metabolism

    Institute of Scientific and Technical Information of China (English)

    张为; 罗建中; 苏德强; 杨建林; 张砾文

    2013-01-01

    微生物共代谢是对污水中难降解性有机物生物降解的一种重要方式,共代谢过程中产生的非专一性关键酶可以促进难降解有机物的降解.大量的研究结果表明,选择合适的菌种和生长基质、控制生长基质和目标污染物的投加比、优化反应条件均可提高共代谢反应的处理效果.基于共代谢的作用机制,分析了影响共代谢的若干影响因子,旨在揭示共代谢对难降解有机物的降解机理.%Microbial co-metabolism is one of the important biodegration methods for microbial non-degradable or-ganics in wastewater treatment. The non-specific key enzymes produced in the co-metabolism process can promote the degradation of refractory organics. A lot of research results show that the treatment efficiency of co-metabolism can be improved by choosing appropriate strain and growth substrate, controlling the adding ratio of growth substances and target pollutants, and optimizing reaction conditions. Based on the action mechanisms of co-metabolism, some influencing factors which affects co-metabolism are analyzed, so as to show the degradation mechanism of non-degradable organics by co-metabolism.

  6. Microbial keratitis in children.

    Science.gov (United States)

    Kunimoto, D Y; Sharma, S; Reddy, M K; Gopinathan, U; Jyothi, J; Miller, D; Rao, G N

    1998-02-01

    Microbial keratitis is a major cause of corneal blindness worldwide. This problem is particularly relevant to children, because most of their visual life is ahead of them, and they are uniquely at risk for irreversible ocular deficits, such as those resulting from amblyopia. The objective of this study was to determine the etiologic agents and predisposing factors in childhood infectious keratitis and to examine the outcome of treatment in terms of structure and visual acuity. The study design was a retrospective cases series. The authors studied 113 eyes in 107 children 16 years of age and younger who were treated for (nonviral) microbial keratitis at the LV Prasad Eye Institute in Hyderabad, India, during the 4.5-year period between February 1, 1991, and June 30, 1995. The patients who met the following criteria were included in the study: (1) corneal stromal infiltrate was present on slit-lamp examination; and (2) a corneal scraping was taken at the time of examination for suspected microbial keratitis. Etiologic micro-organisms, predisposing factors, treatment method, structural treatment outcome, and visual acuity treatment outcome of the infectious keratitis episode were measured. The principal predisposing factors identified in this study were trauma (21.2%), ocular disease (17.7%), systemic disease (15.9%), and prior penetrating keratoplasty in the same eye (8.8%). Vitamin A deficiency was an important factor within the category of severe systemic disease, and contact lens wear was not involved in any of the cases. A total of 85 organisms were isolated in cultures of corneal scrapings from 64 (56.6%) of the 113 cases. Staphylococcus species (43.7%), Streptococcus pneumoniae (18.8%), and fungi (17.2%) were the most common isolates. Eighteen eyes (15.9%) required surgery, and 28 (36.4%) of the 77 patients on whom visual acuity was assessed at last follow-up achieved an unaided visual acuity of 20/60 or better at last follow-up. This work represents the

  7. Risk factors for gastroenteritis: a nested case-control study.

    Science.gov (United States)

    Rodrigo, S; Sinclair, M; Wolfe, R; Leder, K

    2011-04-01

    This nested case-control study investigated the risk factors for gastroenteritis in a cohort using rainwater as their primary domestic water source. Consumption of beef [odds ratio (OR) 2·74, 95% confidence interval (CI) 1·56-4·80], handling of raw fresh chicken in the household (OR 1·52, 95% CI 1·02-2·29) and animal contact (OR 1·83, 95% CI 1·20-2·83) were found to be significant risk factors (P>0·05). Significant protective effects were observed with raw salad prepared at home (OR 0·33, 95% CI 0·18-0·58), consumption of salami (OR 0·60, 95% CI 0·36-0·98), and shellfish (OR 0·31, 95% CI 0·14-0·67). This study provides novel insight into community-based endemic gastroenteritis showing that consumption of beef was associated with increased odds of illness and with a population attributable fraction (PAF) of 57·6%. Detecting such a high PAF for beef in a non-outbreak setting was unexpected.

  8. Transcription factor PIF4 controls the thermosensory activation of flowering

    KAUST Repository

    Kumar, S. Vinod

    2012-03-21

    Plant growth and development are strongly affected by small differences in temperature. Current climate change has already altered global plant phenology and distribution, and projected increases in temperature pose a significant challenge to agriculture. Despite the important role of temperature on plant development, the underlying pathways are unknown. It has previously been shown that thermal acceleration of flowering is dependent on the florigen, FLOWERING LOCUS T (FT). How this occurs is, however, not understood, because the major pathway known to upregulate FT, the photoperiod pathway, is not required for thermal acceleration of flowering. Here we demonstrate a direct mechanism by which increasing temperature causes the bHLH transcription factor PHYTOCHROME INTERACTING FACTOR4 (PIF4) to activate FT. Our findings provide a new understanding of how plants control their timing of reproduction in response to temperature. Flowering time is an important trait in crops as well as affecting the life cycles of pollinator species. A molecular understanding of how temperature affects flowering will be important for mitigating the effects of climate change. © 2012 Macmillan Publishers Limited. All rights reserved.

  9. Efficient simultaneous partial nitrification, anammox and denitrification (SNAD) system equipped with a real-time dissolved oxygen (DO) intelligent control system and microbial community shifts of different substrate concentrations.

    Science.gov (United States)

    Wen, Xin; Gong, Benzhou; Zhou, Jian; He, Qiang; Qing, Xiaoxia

    2017-08-01

    Simultaneous partial nitrification, anammox and denitrification (SNAD) process was studied in a sequencing batch biofilm reactor (SBBR) fed with synthetic wastewater in a range of 2200 mgN/L ∼ 50 mgN/L. Important was an external real-time precision dissolved oxygen (DO) intelligent control system that consisted of feed forward control system and feedback control system. This DO control system permitted close control of oxygen supply according to influent concentration, effluent quality and other environmental factors in the reactor. In this study the operation was divided into six phases according to influent nitrogen applied. SNAD system was successfully set up after adding COD into a CANON system. And the presence of COD enabled the survival of denitrifiers, and made Thauera and Pseudomonas predominant as functional denitrifiers in this system. Denaturing gradient gel electrophoresis (DGGE), fluorescence in situ hybridization (FISH) and 16S rRNA amplicon pyrosequencing were used to analyze the microbial variations of different substrate concentrations. Results indicated that the relative population of ammonia oxidizing bacteria (AOB) members decreased when influent ammonia concentration decreased from 2200 mg/L to 50 mg/L, while no dramatic drop of the percent of anammox bacteria was seen. And Nitrosomonas europaea was the predominant AOB in SNAD system treating sewage, while Candidatus Brocadia was the dominant anammox bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Revisiting factors controlling methane emissions from high-Arctic tundra

    Directory of Open Access Journals (Sweden)

    M. Mastepanov

    2013-07-01

    Full Text Available The northern latitudes are experiencing disproportionate warming relative to the mid-latitudes, and there is growing concern about feedbacks between this warming and methane production and release from high-latitude soils. Studies of methane emissions carried out in the Arctic, particularly those with measurements made outside the growing season, are underrepresented in the literature. Here we present results of 5 yr (2006–2010 of automatic chamber measurements at a high-Arctic location in Zackenberg, NE Greenland, covering both the growing seasons and two months of the following freeze-in periods. The measurements show clear seasonal dynamics in methane emission. The start of the growing season and the increase in CH4 fluxes were strongly related to the date of snowmelt. Within each particular growing season, CH4 fluxes were highly correlated with the soil temperature (R2 > 0.75, which is probably explained by high seasonality of both variables, and weakly correlated with the water table. The greatest variability in fluxes between the study years was observed during the first part of the growing season. Somewhat surprisingly, this variability could not be explained by commonly known factors controlling methane emission, i.e. temperature and water table position. Late in the growing season CH4 emissions were found to be very similar between the study years (except the extremely dry 2010 despite large differences in climatic factors (temperature and water table. Late-season bursts of CH4 coinciding with soil freezing in the autumn were observed during at least three years. The cumulative emission during the freeze-in CH4 bursts was comparable in size with the growing season emission for the year 2007, and about one third of the growing season emissions for the years 2009 and 2010. In all three cases the CH4 burst was accompanied by a corresponding episodic increase in CO2 emission, which can compose a significant contribution to the annual CO2

  11. Risk factors in pediatric asthmatic patients. Cases and control studies.

    Directory of Open Access Journals (Sweden)

    Rafael Alejandro Gómez Baute

    2003-04-01

    Full Text Available Background: Asthma constitutes the first disease among chronic diseases in children. The morbid-mortality promoted to continue being elevated in spite of the new therapies. For this reason it is a disease with high priority for investigation in pediatric ages. Method: A control and case group study was carried out. The samples was composed by 72 asthmatic children from three General Comprehensive doctor offices from Palmira health area located in Cienfuegos Province, Cuba; and a control group of 72 children apparently healthy from the same population. A questionnaire with the different risk variables was elaborated. Odds ratio technique was used to estimate the risk. Results: low weight at birth, family history of asthma, brochiolitis antecedent and the excessive usage of antibiotics in children under 1 year old were the main risks found. Conclusions: It is conclusive that the exposure to home allergen plus a genetic favorable factor, the prematurity, and brochiolitis constituted the most outstanding elements to suffer from asthma in the population studied.

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

    Institute of Scientific and Technical Information of China (English)

    赵波; 贺承祖; 李冬菊

    2012-01-01

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

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

    Science.gov (United States)

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

    2016-05-12

    Considering the extensive functional redundancy in microbial communities and great difficulty in elucidating it based on taxonomic structure, studies on the biogeography of soil microbial activity at large spatial scale are as important as microbial community structure. Eighty-four soil samples were collected across a region from south to north China (about 1,000 km) to address the questions if microbial activity displays biogeographic patterns and what are driving forces. These samples represented different soil types, land use and climate. Redundancy analysis and nonmetric multidimensional scaling clearly revealed that soil microbial activities showed distinct differentiation at different sites over a regional spatial scale, which were strongly affected by soil pH, total P, rainfall, temperature, soil type and location. In addition, microbial community structure was greatly influenced by rainfall, location, temperature, soil pH and soil type and was correlated with microbial activity to some extent. Our results suggest that microbial activities display a clear geographic pattern that is greatly altered by geographic distance and reflected by climate, soil pH and total P over large spatial scales. There are common (distance, climate, pH and soil type) but differentiated aspects (TP, SOC and N) in the biogeography of soil microbial community structure and activity.

  14. Decreases in Soil Moisture and Organic Matter Quality Suppress Microbial Decomposition Following a Boreal Forest Fire

    Energy Technology Data Exchange (ETDEWEB)

    Holden, Sandra R.; Berhe, Asmeret A.; Treseder, Kathleen K.

    2015-08-01

    Climate warming is projected to increase the frequency and severity of wildfires in boreal forests, and increased wildfire activity may alter the large soil carbon (C) stocks in boreal forests. Changes in boreal soil C stocks that result from increased wildfire activity will be regulated in part by the response of microbial decomposition to fire, but post-fire changes in microbial decomposition are poorly understood. Here, we investigate the response of microbial decomposition to a boreal forest fire in interior Alaska and test the mechanisms that control post-fire changes in microbial decomposition. We used a reciprocal transplant between a recently burned boreal forest stand and a late successional boreal forest stand to test how post-fire changes in abiotic conditions, soil organic matter (SOM) composition, and soil microbial communities influence microbial decomposition. We found that SOM decomposing at the burned site lost 30.9% less mass over two years than SOM decomposing at the unburned site, indicating that post-fire changes in abiotic conditions suppress microbial decomposition. Our results suggest that moisture availability is one abiotic factor that constrains microbial decomposition in recently burned forests. In addition, we observed that burned SOM decomposed more slowly than unburned SOM, but the exact nature of SOM changes in the recently burned stand are unclear. Finally, we found no evidence that post-fire changes in soil microbial community composition significantly affect decomposition. Taken together, our study has demonstrated that boreal forest fires can suppress microbial decomposition due to post-fire changes in abiotic factors and the composition of SOM. Models that predict the consequences of increased wildfires for C storage in boreal forests may increase their predictive power by incorporating the observed negative response of microbial decomposition to boreal wildfires.

  15. Geochemical control of microbial Fe(III) reduction potential in wetlands: Comparison of the rhizosphere to non-rhizosphere soil

    Science.gov (United States)

    Weiss, J.V.; Emerson, D.; Megonigal, J.P.

    2004-01-01

    We compared the reactivity and microbial reduction potential of Fe(III) minerals in the rhizosphere and non-rhizosphere soil to test the hypothesis that rapid Fe(III) reduction rates in wetland soils are explained by rhizosphere processes. The rhizosphere was defined as the area immediately adjacent to a root encrusted with Fe(III)-oxides or Fe plaque, and non-rhizosphere soil was 0.5 cm from the root surface. The rhizosphere had a significantly higher percentage of poorly crystalline Fe (66??7%) than non-rhizosphere soil (23??7%); conversely, non-rhizosphere soil had a significantly higher proportion of crystalline Fe (50??7%) than the rhizosphere (18??7%, Psoil Fe(III)-oxide pool. Similarly, microbial reduction consumed 75-80% of the rhizosphere pool in 10 days compared to 30-40% of the non-rhizosphere soil pool. Differences between the two pools persisted when samples were amended with an electron-shuttling compound (AQDS), an Fe(III)-reducing bacterium (Geobacter metallireducens), and organic carbon. Thus, Fe(III)-oxide mineralogy contributed strongly to differences in the Fe(III) reduction potential of the two pools. Higher amounts of poorly crystalline Fe(III) and possibly humic substances, and a higher Fe(III) reduction potential in the rhizosphere compared to the non-rhizosphere soil, suggested the rhizosphere is a site of unusually active microbial Fe cycling. The results were consistent with previous speculation that rapid Fe cycling in wetlands is due to the activity of wetland plant roots. ?? 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

  16. Risk Factors Of Low Birth Weight; Case-Control Study

    Directory of Open Access Journals (Sweden)

    Özgür Önal

    2017-06-01

    Full Text Available Low birth weight (LBW (defined as a birth weight of less than 2500 grams is associated with fetal and neonatal morbidity and mortality, impaired cognitive development, and the advent of chronic diseases in later life. The global incidence of LBW is around 15,5%. The aim of this study was to identify risk factors for low birthweight in the centre of Denizli province. A case-control study was carried out and mothers of 295 newborns with birthweight between 1500-2499 g (cases and 302 newborns with birthweight between 2500-4000 g (controls were analyzed. The questionnare was applied to women using face to face technics between July,2009 and June,2010 . The questionnare included birth weight and birth lenght of newborn, the date of last pregnacy and type of last delivery, profile of mother, anthropometric measures, life styles, habits, addictions, sociodemographic and socioeconomic characteristics of mother and father of newborn. Analysis included frequency and percent distributions, means, standart deviations. In group comparisions for categorical variable, chi square test and odds ratio (OR was used. Logistic regression model was performed for some selected risk factors. P<0.05 was considered statistically significant. Statistical Package for Social Sciences (SPSS program, Version 10 was used for data entry and analysis. When backward logistic regression model was performed for some selected factors in relation to low birth weight, there was a positive relationship between multiple pregnancy [OR(95%CI 18.50 (8.54, 40.39], BMI lower than 20 kg/m2 of mother before pregnancy andemployment status [OR(95%CI 1.98 (1.23, 3.19], weight gain of 7 kg and under during pregnanacy [OR(95%CI 2.49 (1.56, 3.96], a history of giving birth to low birth weight infant [OR(95%CI 3.44 (1.69, 7.02], first- degree and second- degree relative’s histories of giving birth to low birth weight infant [OR(95%CI 4.28 (2.61, 6.94], X- ray exposure in the three months before and

  17. Hydrologic factors controlling groundwater salinity in northwestern coastal zone, Egypt

    Indian Academy of Sciences (India)

    Nahla A Morad; M H Masoud; S M Abdel Moghith

    2014-10-01

    The aim of this article is to assess the main factors influencing salinity of groundwater in the coastal area between El Dabaa and Sidi Barani, Egypt. The types and ages of the main aquifers in this area are the fractured limestone of Middle Miocene, the calcareous sandstone of Pliocene and the Oolitic Limestone of Pleistocene age. The aquifers in the area are recharged by seasonal rainfall of the order of 150 mm/year. The relationship of groundwater salinity against the absolute water level, the well drilling depth, and the ability of aquifer to recharge has been discussed in the present work. The ability of aquifer to locally recharge by direct rainfall is a measure of the vertical permeability due to lithological and structural factors that control groundwater salinity in the investigated aquifers. On the other hand, the fracturing system as well as the attitude of the surface water divide has a prime role in changing both the mode of occurrence and the salinity of groundwater in the area. Directly to the west of Matrouh, where the coastal plain is the narrowest, and east of Barrani, where the coastal plain is the widest, are good examples of this concept, where the water salinity attains its maximum and minimum limits respectively. Accordingly, well drilling in the Miocene aquifer, in the area between El Negila and Barrani to get groundwater of salinities less than 5000 mg/l is recommended in this area, at flow rate less than 10m3/hr/well. In other words, one can expect that the brackish water is probably found where the surface water divide is far from the shore line, where the Wadi fill deposits dominate (Quaternary aquifer), acting as a possible water salinity by direct rainfall and runoff.

  18. 75 FR 69912 - Pipeline Safety: Control Room Management/Human Factors

    Science.gov (United States)

    2010-11-16

    ... Safety: Control Room Management/Human Factors AGENCY: Pipeline and Hazardous Materials Safety..., 2010, PHMSA published a Control Room Management/Human Factors notice of proposed rulemaking (NPRM... to expedite the program implementation deadlines of the Control Room Management/Human Factors rule...

  19. 75 FR 5536 - Pipeline Safety: Control Room Management/Human Factors, Correction

    Science.gov (United States)

    2010-02-03

    ... Safety: Control Room Management/Human Factors, Correction AGENCY: Pipeline and Hazardous Materials Safety... Regulations to address human factors and other aspects of control room management for pipelines where... 63310) entitled ``Pipeline Safety: Control Room Management/Human Factors.'' This final rule...

  20. Factors controlling high-frequency radiation from extended ruptures

    Science.gov (United States)

    Beresnev, Igor A.

    2017-09-01

    Small-scale slip heterogeneity or variations in rupture velocity on the fault plane are often invoked to explain the high-frequency radiation from earthquakes. This view has no theoretical basis, which follows, for example, from the representation integral of elasticity, an exact solution for the radiated wave field. The Fourier transform, applied to the integral, shows that the seismic spectrum is fully controlled by that of the source time function, while the distribution of final slip and rupture acceleration/deceleration only contribute to directivity. This inference is corroborated by the precise numerical computation of the full radiated field from the representation integral. We compare calculated radiation from four finite-fault models: (1) uniform slip function with low slip velocity, (2) slip function spatially modulated by a sinusoidal function, (3) slip function spatially modulated by a sinusoidal function with random roughness added, and (4) uniform slip function with high slip velocity. The addition of "asperities," both regular and irregular, does not cause any systematic increase in the spectral level of high-frequency radiation, except for the creation of maxima due to constructive interference. On the other hand, an increase in the maximum rate of slip on the fault leads to highly amplified high frequencies, in accordance with the prediction on the basis of a simple point-source treatment of the fault. Hence, computations show that the temporal rate of slip, not the spatial heterogeneity on faults, is the predominant factor forming the high-frequency radiation and thus controlling the velocity and acceleration of the resulting ground motions.

  1. Controllability analysis of transcriptional regulatory networks reveals circular control patterns among transcription factors.

    Science.gov (United States)

    Österlund, Tobias; Bordel, Sergio; Nielsen, Jens

    2015-05-01

    Transcriptional regulation is the most committed type of regulation in living cells where transcription factors (TFs) control the expression of their target genes and TF expression is controlled by other TFs forming complex transcriptional regulatory networks that can be highly interconnected. Here we analyze the topology and organization of nine transcriptional regulatory networks for E. coli, yeast, mouse and human, and we evaluate how the structure of these networks influences two of their key properties, namely controllability and stability. We calculate the controllability for each network as a measure of the organization and interconnectivity of the network. We find that the number of driver nodes nD needed to control the whole network is 64% of the TFs in the E. coli transcriptional regulatory network in contrast to only 17% for the yeast network, 4% for the mouse network and 8% for the human network. The high controllability (low number of drivers needed to control the system) in yeast, mouse and human is due to the presence of internal loops in their regulatory networks where the TFs regulate each other in a circular fashion. We refer to these internal loops as circular control motifs (CCM). The E. coli transcriptional regulatory network, which does not have any CCMs, shows a hierarchical structure of the transcriptional regulatory network in contrast to the eukaryal networks. The presence of CCMs also has influence on the stability of these networks, as the presence of cycles can be associated with potential unstable steady-states where even small changes in binding affinities can cause dramatic rearrangements of the state of the network.

  2. Carbon isotopic evidence for microbial control of carbon supply to Orca Basin at the brine-seawater interface

    Directory of Open Access Journals (Sweden)

    S. R. Shah

    2012-12-01

    Full Text Available Orca Basin, an intraslope basin on the Texas–Louisiana continental slope, hosts a hypersaline, anoxic brine in its lowermost 200 m. This brine contains a large reservoir of reduced and aged carbon, and appears to be stable at decadal time scales: concentrations and the isotopic composition of dissolved inorganic (DIC and organic carbon (DOC are similar to previous reports. Both DIC and DOC are more "aged" within the brine pool than in overlying water, and the isotopic contrast between brine carbon and seawater carbon is much greater for DIC than DOC. While the stable carbon isotopic composition of brine DIC points towards a combination of methane and organic carbon re-mineralization as its source, radiocarbon and box model results point to the brine interface as the major source region for DIC with oxidation of methane diffusing upwards from sediments supplying only limited DIC to the brine. This conclusion is consistent with previous studies reporting microbial activity focused at the seawater-brine interface. Isotopic similarities between DIC and DOC suggest a different relationship between these two carbon reservoirs than is typically observed in deep ocean basins. Radiocarbon values implicate the seawater-brine interface region as the likely source region for DOC as well as DIC. Further investigations of the seawater-brine interface are needed to advance our understanding of the specific microbial processes contributing to dissolved carbon storage in the Orca Basin brine.

  3. Degradation of 1,1,2,2-Tetrachloroethane by Microbial Consortia in Wetland Sediment: Controls on 1,2-Dichloroethane and Vinyl Chloride Accumulation

    Science.gov (United States)

    Lorah, M. M.; Voytek, M. A.

    2001-05-01

    Concurrent geochemical analyses of porewater and genetic analyses of wetland sediment over time in laboratory microcosm experiments are being used to define biodegradation pathways of 1,1,2,2-tetrachloroethane (PCA) and associated critical microorganisms in anaerobic wetland sediments. These experiments were conducted to better understand factors controlling in situ daughter product distribution as part of a study of natural attenuation of a chlorinated solvent plume that is discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Possible biodegradation pathways of PCA under anaerobic conditions include (1) sequential hydrogenolysis of PCA to 1,1,2-trichloroethane (TCA), 1,2-dichloroethane (DCA), chloroethane, and ethane; (2) hydrogenolysis of PCA to TCA followed by dichloroelimination of TCA to vinyl chloride (VC); and (3) dichloroelimination of PCA to cis- and trans-1,2-dichloroethene (DCE) and subsequent hydrogenolysis of DCE to VC. Elucidation of factors controlling the occurrence of these diverse pathways is critical because of differing toxicity and persistence of the daughter products. Microcosm experiments were conducted in March and July 1999 using wetland sediment and porewater collected at two contaminated sites in the study area-one characterized as predominantly methanogenic (WB23) and one characterized as mixed iron-reducing and methanogenic (WB30)-and amended only with PCA or TCA. Microcosm water was analyzed for volatile organic compounds, methane, ferrous iron, and sulfate, while genetic analyses of the corresponding microcosm sediment were used to obtain profiles of bacteria and methanogenic communities at each time step. All PCA-amended microcosms showed simultaneous production of TCA (from hydrogenolysis) and DCE (from dichloroelimination) from day 1. Subsequently, DCA became the predominant daughter product in microcosms constructed with WB23 sediment, which showed high methane production throughout the experiment

  4. Microbial carbon recycling: an underestimated process controlling soil carbon dynamics - Part 2: A C3-C4 vegetation change field labelling experiment

    Science.gov (United States)

    Basler, A.; Dippold, M.; Helfrich, M.; Dyckmans, J.

    2015-11-01

    The mean residence times (MRT) of different compound classes of soil organic matter (SOM) do not match their inherent recalcitrance to decomposition. One reason for this is the stabilization within the soil matrix, but recycling, i.e. the reuse of "old" organic material to form new biomass may also play a role as it uncouples the residence times of organic matter from the lifetime of discrete molecules in soil. We analysed soil sugar dynamics in a natural 30-year old labelling experiment after a wheat-maize vegetation change to determine the extent of recycling and stabilization by assessing differences in turnover dynamics between plant and microbial-derived sugars: while plant-derived sugars are only affected by stabilization processes, microbial sugars may be subject to both, stabilization and recycling. To disentangle the dynamics of soil sugars, we separated different density fractions (free particulate organic matter (fPOM), light occluded particulate organic matter (≤ 1.6 g cm-3; oPOM1.6), dense occluded particulate organic matter (≤ 2 g cm-3; oPOM2) and mineral-associated organic matter (> 2 g cm-3; mineral)) of a silty loam under long-term wheat and maize cultivation. The isotopic signature of neutral sugars was measured by high pressure liquid chromatography coupled to isotope ratio mass spectrometry (HPLC/IRMS), after hydrolysis with 4 M Trifluoroacetic acid. While apparent MRT of sugars were comparable to total organic carbon in the bulk soil and mineral fraction, the apparent MRT of sugar carbon in the oPOM fractions were considerably lower than those of the total carbon of these fractions. This indicates that oPOM formation was fuelled by microbial activity feeding on new plant input. In the bulk soil, MRT of the mainly plant-derived xylose were significantly lower than those of mainly microbial-derived sugars like galactose, rhamnose, fucose, indicating that recycling of organic matter is an important factor regulating organic matter dynamics in

  5. The Effects of Fungicide, Soil Fumigant, Bio-Organic Fertilizer and Their Combined Application on Chrysanthemum Fusarium Wilt Controlling, Soil Enzyme Activities and Microbial Properties.

    Science.gov (United States)

    Zhao, Shuang; Chen, Xi; Deng, Shiping; Dong, Xuena; Song, Aiping; Yao, Jianjun; Fang, Weimin; Chen, Fadi

    2016-04-21

    Sustained monoculture often leads to a decline in soil quality, in particular to the build-up of pathogen populations, a problem that is conventionally addressed by the use of either fungicide and/or soil fumigation. This practice is no longer considered to be either environmentally sustainable or safe. While the application of organic fertilizer is seen as a means of combating declining soil fertility, it has also been suggested as providing some control over certain soil-borne plant pathogens. Here, a greenhouse comparison was made of the Fusarium wilt control efficacy of various treatments given to a soil in which chrysanthemum had been produced continuously for many years. The treatments comprised the fungicide carbendazim (MBC), the soil fumigant dazomet (DAZ), the incorporation of a Paenibacillus polymyxa SQR21 (P. polymyxa SQR21, fungal antagonist) enhanced bio-organic fertilizer (BOF), and applications of BOF combined with either MBC or DAZ. Data suggest that all the treatments evaluated show good control over Fusarium wilt. The MBC and DAZ treatments were effective in suppressing the disease, but led to significant decrease in urease activity and no enhancement of catalase activity in the rhizosphere soils. BOF including treatments showed significant enhancement in soil enzyme activities and microbial communities compared to the MBC and DAZ, evidenced by differences in bacterial/fungi (B/F) ratios, Shannon-Wiener indexes and urease, catalase and sucrase activities in the rhizosphere soil of chrysanthemum. Of all the treatments evaluated, DAZ/BOF application not only greatly suppressed Fusarium wilt and enhanced soil enzyme activities and microbial communities but also promoted the quality of chrysanthemum obviously. Our findings suggest that combined BOF with DAZ could more effectively control Fusarium wilt disease of chrysanthemum.

  6. Microbial dynamics in natural aquifers

    OpenAIRE

    Bajracharya, Bijendra Man

    2016-01-01

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

  7. Factors affecting the microbial and chemical composition of silage. III. Effect of urea additions on maize silage.

    Science.gov (United States)

    Mahmoud, S A; Abd-el-Hafez, A; Zaki, M M; Saleh, E A

    1978-01-01

    The effect of urea additions on the microbiological and chemical properties of silage, produced from young maize plants (Darawa stage), was studied. Urea treatments, i.e., 0.25%, 0.50%, 0.75%, and 1.00%, stimulated higher densities of the desired microorganisms than the control, while undesired organisms showed lower counts (proteolytic and saccharolytic anaerobes). Addition of 0.25 to 0.50% or urea resulted in the production of high quality silage with pleasant small and high nutritive value, as confirmed by the various microbiological and chemical analyses conducted. Higher levels (0.75 and 1.00%) of urea decreased the quality of the product.

  8. Factors controlling large-wood transport in a mountain river

    Science.gov (United States)

    Ruiz-Villanueva, Virginia; Wyżga, Bartłomiej; Zawiejska, Joanna; Hajdukiewicz, Maciej; Stoffel, Markus

    2016-11-01

    As with bedload transport, wood transport in rivers is governed by several factors such as flow regime, geomorphic configuration of the channel and floodplain, or wood size and shape. Because large-wood tends to be transported during floods, safety and logistical constraints make field measurements difficult. As a result, direct observation and measurements of the conditions of wood transport are scarce. This lack of direct observations and the complexity of the processes involved in wood transport may result in an incomplete understanding of wood transport processes. Numerical modelling provides an alternative approach to addressing some of the unknowns in the dynamics of large-wood in rivers. The aim of this study is to improve the understanding of controls governing wood transport in mountain rivers, combining numerical modelling and direct field observations. By defining different scenarios, we illustrate relationships between the rate of wood transport and discharge, wood size, and river morphology. We test these relationships for a wide, multithread reach and a narrower, partially channelized single-thread reach of the Czarny Dunajec River in the Polish Carpathians. Results indicate that a wide range of quantitative information about wood transport can be obtained from a combination of numerical modelling and field observations and from document contrasting patterns of wood transport in single- and multithread river reaches. On the one hand, log diameter seems to have a greater importance for wood transport in the multithread channel because of shallower flow, lower flow velocity, and lower stream power. Hydrodynamic conditions in the single-thread channel allow transport of large-wood pieces, whereas in the multithread reach, logs with diameters similar to water depth are not being moved. On the other hand, log length also exerts strong control on wood transport, more so in the single-thread than in the multithread reach. In any case, wood transport strongly

  9. Microbial xanthophylls.

    Science.gov (United States)

    Bhosale, Prakash; Bernstein, Paul S

    2005-09-01

    Xanthophylls are oxygenated carotenoids abundant in the human food supply. Lutein, zeaxanthin, and cryptoxanthin are major xanthophyll carotenoids in human plasma. The consumption of these xanthophylls is directly associated with reduction in the risk of cancers, cardiovascular disease, age-related macular degeneration, and cataract formation. Canthaxanthin and astaxanthin also have considerable importance in aquaculture for salmonid and crustacean pigmentation, and are of commercial interest for the pharmaceutical and food industries. Chemical synthesis is a major source for the heavy demand of xanthophylls in the consumer market; however, microbial producers also have potential as commercial sources. In this review, we discuss the biosynthesis, commercial utility, and major microbial sources of xanthophylls. We also present a critical review of current research and technologies involved in promoting microbes as potential commercial sources for mass production.

  10. Comparing a microbial biocide and chlorine as zebra mussel control strategies in an Irish drinking water treatment plant

    National Research Council Canada - National Science Library

    Sara Meehan; Frances E. Lucy; Bridget Gruber; Sarahann Rackl

    2013-01-01

    A need exists for an environmentally friendly mussel control method to replace chlorine and other traditional control methods currentlyutilised in drinking water plants and other infested facilities. Zequanox...

  11. What factors control the size of an eruption?

    Science.gov (United States)

    Gudmundsson, Agust

    2017-04-01

    pressure so as to drive out magma for a much longer time during an eruption than is otherwise possible. As a consequence a much higher proportion of the magma in the chamber is driven or squeezed out during an eruption associated with caldera or graben subsidence than is possible during an ordinary poroelastic chamber behaviour. It follows that the volume of eruptive materials may approach the total volume of the chamber resulting in a large eruption. Here a large eruption is thus the consequence—not the cause—of the subsidence of the caldera/graben block. Thus, once the factors controlling large-scale subsidence of a caldera/graben block are established during a particular unrest/rifting episode, primarily using geodetic and seismic data, the probability of a large eruption can be assessed and used for reliable forecasting. Gudmundsson, A., 2015. Collapse-driven large eruptions. Journal of Volcanology and Geothermal Research, 304, 1-10. Gudmundsson, A., 2016. The mechanics of large volcanic eruptions. Earth-Science Reviews, 163, 72-93.

  12. Microbial diversity in alpine tundra soils correlates with snow cover dynamics.

    Science.gov (United States)

    Zinger, Lucie; Shahnavaz, Bahar; Baptist, Florence; Geremia, Roberto A; Choler, Philippe

    2009-07-01

    The temporal and spatial snow cover dynamics is the primary factor controlling the plant communities' composition and biogeochemical cycles in arctic and alpine tundra. However, the relationships between the distribution of snow and the diversity of soil microbial communities remain largely unexplored. Over a period of 2 years, we monitored soil microbial communities at three sites, including contiguous alpine meadows of late and early snowmelt locations (LSM and ESM, respectively). Bacterial and fungal communities were characterized by using molecular fingerprinting and cloning/sequencing of microbial ribosomal DNA extracted from the soil. Herein, we show that the spatial and temporal distribution of snow strongly correlates with microbial community composition. High seasonal contrast in ESM is associated with marked seasonal shifts for bacterial communities; whereas less contrasted seasons because of long-lasting snowpack in LSM is associated with increased fungal diversity. Finally, our results indicate that, similar to plant communities, microbial communities exhibit important shifts in composition at two extremes of the snow cover gradient. However, winter conditions lead to the convergence of microbial communities independently of snow cover presence. This study provides new insights into the distribution of microbial communities in alpine tundra in relation to snow cover dynamics, and may be helpful in predicting the future of microbial communities and biogeochemical cycles in arctic and alpine tundra in the context of a warmer climate.

  13. Diabetes and age-related demographic differences in risk factor control.

    Science.gov (United States)

    Egan, Brent M; Li, Jiexiang; Wolfman, Tamara E; Sinopoli, Angelo

    2014-06-01

    Disparate vascular outcomes in diabetes by race and/or ethnicity may reflect differential risk factor control, especially pre-Medicare. Assess concurrent target attainment for glycohemoglobin 2, P factor awareness and treatment were lower in Hispanics than whites. When treated, diabetes and hypertension control were greater in whites than blacks or Hispanics. Concurrent risk factor control is low in all diabetics and could improve with greater statin use. Insuring younger adults, especially Hispanic, could raise risk factor awareness and treatment. Improving treatment effectiveness in younger black and Hispanic diabetics could promote equitable risk factor control.

  14. Experimental evolution on a wild mammal species results in modifications of gut microbial communities

    Directory of Open Access Journals (Sweden)

    Kevin eKohl

    2016-05-01

    Full Text Available Comparative studies have shown that diet, life history, and phylogeny interact to determine microbial community structure across mammalian hosts. However, these studies are often confounded by numerous factors. Selection experiments offer unique opportunities to validate conclusions and test hypotheses generated by comparative studies. We used a replicated, 15-generation selection experiment on bank voles (Myodes glareolus that have been selected for high swim-induced aerobic metabolism, predatory behavior towards crickets, and the ability to maintain body mass on a high-fiber, herbivorous diet. We predicted that selection on host performance, mimicking adaptive radiation, would result in distinct microbial signatures. We collected foregut and cecum samples from animals that were all fed the same nutrient-rich diet and had not been subjected to any performance tests. We conducted microbial inventories of gut contents by sequencing the V4 region of the 16S rRNA gene. We found no differences in cecal microbial community structure or diversity between control lines and the aerobic or predatory lines. However, the cecal chambers of voles selected for herbivorous capability harbored distinct microbial communities that exhibited higher diversity than control lines. The foregut communities of herbivorous-selected voles were also distinct from control lines. Overall, this experiment suggests that differences in microbial communities across herbivorous mammals may be evolved, and not solely driven by current diet or other transient factors.

  15. Key Factors Controlling the Growth of Biological Soil Crusts: Towards a Protocol to Produce Biocrusts in Greenhouse Facilities

    Science.gov (United States)

    Velasco Ayuso, Sergio; María Giraldo Silva, Ana; Nelson, Corey; Barger, Nichole; Antoninka, Anita; Bowker, Matthew; Garcia-Pichel, Ferran

    2016-04-01

    Biological soil crusts (= biocrusts) are topsoil communities comprise of, but not limited to, cyanobacteria, algae, lichens, and mosses that grow intimately associated with soil particles in drylands. Biocrusts have central ecological roles in these areas as sources of carbon and nutrients, and efficiently retain water and prevent soil erosion, which improves soil structure and promotes soil fertility. However, human activities, such as cattle grazing, hiking or military training, are rapidly striking biocrusts. Although it is well known that the inoculation with cyanobacteria or lichens can enhance the recovery of biocrusts in degraded soils, little is known about the factors that control their growth rates. Using soil and inocula from four different sites located in one cold desert (Utah) and in one hot desert (New Mexico), we performed a fractional factorial experiment involving seven factors (water, light, P, N, calcium carbonate, trace metals and type of inoculum) to screen their effects on the growth of biocrusts. After four months, we measured the concentration of chlorophyll a, and we discovered that water, light and P, N or P+N were the most important factors controlling the growth of biocrusts. In the experimental treatments involving these three factors we measured a similar concentration of chlorophyll a (or even higher) to this found in the field locations. Amplification of the 16S rRNA gene segment using universal bacteria primers revealed a microbial community composition in the biocrusts grown that closely corresponds to initial measurements made on inocula. In summary, based on our success in obtaining biocrust biomass from natural communities in greenhouse facilities, without significantly changing its community composition at the phylum and cyanobacterial level, we are paving the road to propose a protocol to produce a high quality-nursed inoculum aiming to assist restoration of arid and semi-arid ecosystems affected by large-scale disturbances.

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

    DEFF Research Database (Denmark)

    Cao, Haichuan; Chen, Ruirui; Wang, Libing

    2016-01-01

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

  17. Factors controlling the initiation of Snowball Earth events

    Science.gov (United States)

    Voigt, A.

    2012-12-01

    During the Neoproterozoic glaciations tropical continents were covered by active glaciers that extended down to sea level. To explain these glaciers, the Snowball Earth hypothesis assumes that oceans were completely sea-ice covered during these glaciation, but there is an ongoing debate whether or not some regions of the tropical oceans remained open. In this talk, I will describe past and ongoing climate modelling activities with the comprehensive coupled climate model ECHAM5/MPI-OM that identify and compare factors that control the initiation of Snowball Earth events. I first show that shifting the continents from their present-day location to their Marinoan (635 My BP) low-latitude location increases the planetary albedo, cools the climate, and thereby allows Snowball Earth initiation at higher levels of total solar irradiance and atmospheric CO2. I then present simulations with successively lowered bare sea-ice albedo, disabled sea-ice dynamics, and switched-off ocean heat transport. These simulations show that both lowering the bare sea-ice albedo and disabling sea-ice dynamics increase the critical sea-ice cover in ECHAM5/MPI-OM, but sea-ice dynamics due to strong equatorward sea-ice transport have a much larger influence on the critical CO2. Disabling sea-ice transport allows a state with sea-ice margin at 10 deg latitude by virtue of the Jormungand mechanism. The accumulation of snow on land, in combination with tropical land temperatures below or close to freezing, suggests that tropical land glaciers could easily form in such a state. However, in contrast to aquaplanet simulations without ocean heat transport, there is no sign of a Jormungand hysteresis in the coupled simulations. Ocean heat transport is not responsible for the lack of a Jormungand hysteresis in the coupled simulations. By relating the above findings to previous studies, I will outline promising future avenues of research on the initiation of Snowball Earth events. In particular, an

  18. Molecular factors controlling photosynthetic light harvesting by carotenoids.

    Science.gov (United States)

    Polívka, Tomás; Frank, Harry A

    2010-08-17

    Carotenoids are naturally occurring pigments that absorb light in the spectral region in which the sun irradiates maximally. These molecules transfer this energy to chlorophylls, initiating the primary photochemical events of photosynthesis. Carotenoids also regulate the flow of energy within the photosynthetic apparatus and protect it from photoinduced damage caused by excess light absorption. To carry out these functions in nature, carotenoids are bound in discrete pigment-protein complexes in the proximity of chlorophylls. A few three-dimensional structures of these carotenoid complexes have been determined by X-ray crystallography. Thus, the stage is set for attempting to correlate the structural information with the spectroscopic properties of carotenoids to understand the molecular mechanism(s) of their function in photosynthetic systems. In this Account, we summarize current spectroscopic data describing the excited state energies and ultrafast dynamics of purified carotenoids in solution and bound in light-harvesting complexes from purple bacteria, marine algae, and green plants. Many of these complexes can be modified using mutagenesis or pigment exchange which facilitates the elucidation of correlations between structure and function. We describe the structural and electronic factors controlling the function of carotenoids as energy donors. We also discuss unresolved issues related to the nature of spectroscopically dark excited states, which could play a role in light harvesting. To illustrate the interplay between structural determinations and spectroscopic investigations that exemplifies work in the field, we describe the spectroscopic properties of four light-harvesting complexes whose structures have been determined to atomic resolution. The first, the LH2 complex from the purple bacterium Rhodopseudomonas acidophila, contains the carotenoid rhodopin glucoside. The second is the LHCII trimeric complex from higher plants which uses the carotenoids

  19. Investigating the effective factors on management internal controls applying

    Directory of Open Access Journals (Sweden)

    Ahmad Ahmadkhani

    2012-08-01

    Full Text Available Information technology plays an important role on increasing internal control in many organizations. In this paper, we present an empirical study to measure the impact of information technology, hiring high quality skilled management team, using high quality standards and increasing employees' awareness on managing internal control. The survey uses a questionnaire based on Likert scale and distributes among the people who work in either administration or financial sectors of governmental agencies in province of Zanjan, Iran. The results of the study indicate that the implementation of information technology positively influences management team to control their system, more effectively, using more skilled and specialized managers positively influences management internal control, an organization with suitable standard positively influences management internal control and increasing employees' awareness positively influences management internal control.

  20. Environmental exogenous factors and facial dermatitis: A case control study

    Directory of Open Access Journals (Sweden)

    Wen-Hui Wang

    2017-03-01

    Conclusions: Contact factors play an important role in facial dermatitis. Aggravation by sunlight exposure, ingestion of spicy food, or alcohol are more reported in facial dermatitis compared with nonfacial dermatitis.

  1. Numerical Modeling Analysis of Hydrodynamic and Microbial Controls on DNAPL Pool Dissolution and Detoxification: Dehalorespirers in Co-culture

    Energy Technology Data Exchange (ETDEWEB)

    Wesseldyke, Eric S.; Becker, Jennifer G.; Seagren, Eric A.; Mayer, Alex S.; Zhang, Changyong

    2015-04-01

    Dissolution of dense non-aqueous phase liquid (DNAPL) contaminants like tetrachloroethene (PCE) can be “bioenhanced” via biodegradation, which increases the concentration gradient at the DNAPL–water interface. Model simulations were used to evaluate the impact of ecological interactions between different dehalorespiring strains and hydrodynamics on the bioenhancement effect and the extent of PCE dechlorination. Simulations were performed using a two-dimensional coupled flow-transport model, with a DNAPL pool source and two microbial species, Dehalococcoides mccartyi 195 and Desulfuromonas michiganensis, which compete for electron acceptors (e.g., PCE), but not for their electron donors. Under biostimulation, low vx conditions, D. michiganensis alone significantly enhanced dissolution by rapidly utilizing aqueous-phase PCE. In co-culture under these conditions, D. mccartyi 195 increased this bioenhancement modestly and greatly increased the extent of PCE transformation. Although D. michiganensis was the dominant population under low velocity conditions, D. mccartyi 195 dominated under high velocity conditions due to bioclogging effects.

  2. Simultaneous water desalination and electricity generation in a microbial desalination cell with electrolyte recirculation for pH control

    KAUST Repository

    Qu, Youpeng

    2012-02-01

    A recirculation microbial desalination cell (rMDC) was designed and operated to allow recirculation of solutions between the anode and cathode chambers. This recirculation avoided pH imbalances that could inhibit bacterial metabolism. The maximum power density was 931±29mW/m 2 with a 50mM phosphate buffer solution (PBS) and 776±30mW/m 2 with 25mM PBS. These power densities were higher than those obtained without recirculation of 698±10mW/m 2 (50mM PBS) and 508±11mW/m 2 (25mM PBS). The salt solution (20g/L NaCl) was reduced in salinity by 34±1% (50mM) and 37±2% (25mM) with recirculation (rMDC), and by 39±1% (50mM) and 25±3% (25mM) without recirculation (MDC). These results show that electrolyte recirculation using an rMDC is an effective method to increase power and achieve efficient desalination by eliminating pH imbalances. © 2011 Elsevier Ltd.

  3. Biogas production and microbial community shift through neutral pH control during the anaerobic digestion of pig manure.

    Science.gov (United States)

    Zhou, Jun; Zhang, Rui; Liu, Fenwu; Yong, Xiaoyu; Wu, Xiayuan; Zheng, Tao; Jiang, Min; Jia, Honghua

    2016-10-01

    Laboratory-scale reactors, in which the pH could be auto-adjusted, were employed to investigate the mesophilic methane fermentation with pig manure (7.8% total solids) at pH 6.0, 7.0, and 8.0. Results showed that the performance of anaerobic digestion was strongly dependent on pH value. Biogas production and methane content at neutral pH 7.0 were significantly higher (16,607mL, 51.81%) than those at pH 6.0 (6916mL, 42.9%) and 8.0 (9739mL, 35.6%). Denaturing gradient gel electrophoresis fingerprinting and Shannon's index indicated that the samples contained highly diverse microbial communities. The major genus at pH 7.0 was Methanocorpusculum, compared with that was Methanosarcina at both pH 6.0 and 8.0. Our research revealed that cultures maintained at pH 7.0 could support increased biogas production, which has significant implications for the scale-up biogas engineering.

  4. Degradation of microbial polyesters.

    Science.gov (United States)

    Tokiwa, Yutaka; Calabia, Buenaventurada P

    2004-08-01

    Microbial polyhydroxyalkanoates (PHAs), one of the largest groups of thermoplastic polyesters are receiving much attention as biodegradable substitutes for non-degradable plastics. Poly(D-3-hydroxybutyrate) (PHB) is the most ubiquitous and most intensively studied PHA. Microorganisms degrading these polyesters are widely distributed in various environments. Although various PHB-degrading microorganisms and PHB depolymerases have been studied and characterized, there are still many groups of microorganisms and enzymes with varying properties awaiting various applications. Distributions of PHB-degrading microorganisms, factors affecting the biodegradability of PHB, and microbial and enzymatic degradation of PHB are discussed in this review. We also propose an application of a new isolated, thermophilic PHB-degrading microorganism, Streptomyces strain MG, for producing pure monomers of PHA and useful chemicals, including D-3-hydroxycarboxylic acids such as D-3-hydroxybutyric acid, by enzymatic degradation of PHB.

  5. Microbial Metalloproteomics

    Directory of Open Access Journals (Sweden)

    Peter-Leon Hagedoorn

    2015-12-01

    Full Text Available Metalloproteomics is a rapidly developing field of science that involves the comprehensive analysis of all metal-containing or metal-binding proteins in a biological sample. The purpose of this review is to offer a comprehensive overview of the research involving approaches that can be categorized as inductively coupled plasma (ICP-MS based methods, X-ray absorption/fluorescence, radionuclide based methods and bioinformatics. Important discoveries in microbial proteomics will be reviewed, as well as the outlook to new emerging approaches and research areas.

  6. Vehicle fingertip reach controls--human factors recommendations.

    Science.gov (United States)

    Moussa-Hamouda, E; Mourant, R R

    1981-06-01

    Interviews were conducted with 405 drivers of cars equipped with fingertip reach controls. A high percentage of finding problems was reported when the horn was mounted on a stalk and also when the turn signal was on a right stalk. Drivers of configurations with two left stalks had a large percentage of inadvertent operation problems for the turn signal and for the headlight beam selector. A laboratory experiment was conducted to evaluate modes of operation for the wiper on/off, wiper speed and washer on/off functions. Subjects performed best when the wiper on/off and speed control were actuated by a rotating had switch. Subjects' reactions to stalk mounted controls were much faster than their reactions to dash mounted controls. Recommendations to eliminate finding and inadvertent operation problems associated with fingertip reach controls are given.

  7. Medium factors on anaerobic production of rhamnolipids by Pseudomonas aeruginosa SG and a simplifying medium for in situ microbial enhanced oil recovery applications.

    Science.gov (United States)

    Zhao, Feng; Zhou, Jidong; Han, Siqin; Ma, Fang; Zhang, Ying; Zhang, Jie

    2016-04-01

    Aerobic production of rhamnolipid by Pseudomonas aeruginosa was extensively studied. But effect of medium composition on anaerobic production of rhamnolipid by P. aeruginosa was unknown. A simplifying medium facilitating anaerobic production of rhamnolipid is urgently needed for in situ microbial enhanced oil recovery (MEOR). Medium factors affecting anaerobic production of rhamnolipid were investigated using P. aeruginosa SG (Genbank accession number KJ995745). Medium composition for anaerobic production of rhamnolipid by P. aeruginosa is different from that for aerobic production of rhamnolipid. Both hydrophobic substrate and organic nitrogen inhibited rhamnolipid production under anaerobic conditions. Glycerol and nitrate were the best carbon and nitrogen source. The commonly used N limitation under aerobic conditions was not conducive to rhamnolipid production under anaerobic conditions because the initial cell growth demanded enough nitrate for anaerobic respiration. But rhamnolipid was also fast accumulated under nitrogen starvation conditions. Sufficient phosphate was needed for anaerobic production of rhamnolipid. SO4(2-) and Mg(2+) are required for anaerobic production of rhamnolipid. Results will contribute to isolation bacteria strains which can anaerobically produce rhamnolipid and medium optimization for anaerobic production of rhamnolipid. Based on medium optimization by response surface methodology and ions composition of reservoir formation water, a simplifying medium containing 70.3 g/l glycerol, 5.25 g/l NaNO3, 5.49 g/l KH2PO4, 6.9 g/l K2HPO4·3H2O and 0.40 g/l MgSO4 was designed. Using the simplifying medium, 630 mg/l of rhamnolipid was produced by SG, and the anaerobic culture emulsified crude oil to EI24 = 82.5 %. The simplifying medium was promising for in situ MEOR applications.

  8. Microbial Ecosystems, Protection of

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Nelson, K.E.

    2014-01-01

    Synonyms Conservation of microbial diversity and ecosystem functions provided by microbes; Preservation of microbial diversity and ecosystem functions provided by microbes Definition The use, management, and conservation of ecosystems in order to preserve microbial diversity and functioning.

  9. Microbial Ecosystems, Protection of

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Nelson, K.E.

    2014-01-01

    Synonyms Conservation of microbial diversity and ecosystem functions provided by microbes; Preservation of microbial diversity and ecosystem functions provided by microbes Definition The use, management, and conservation of ecosystems in order to preserve microbial diversity and functioning. Introdu

  10. From lithotroph- to organotroph-dominant: directional shift of microbial community in sulphidic tailings during phytostabilization

    Science.gov (United States)

    Li, Xiaofang; Bond, Philip L.; Van Nostrand, Joy D.; Zhou, Jizhong; Huang, Longbin

    2015-01-01

    Engineering microbial diversity to enhance soil functions may improve the success of direct revegetation in sulphidic mine tailings. Therefore, it is essential to explore how remediation and initial plant establishment can alter microbial communities, and, which edaphic factors control these changes under field conditions. A long-term revegetation trial was established at a Pb-Zn-Cu tailings impoundment in northwest Queensland. The control and amended and/or revegetated treatments were sampled from the 3-year-old trial. In total, 24 samples were examined using pyrosequencing of 16S rRNA genes and various chemical properties. The results showed that the microbial diversity was positively controlled by soil soluble Si and negatively controlled by soluble S, total Fe and total As, implying that pyrite weathering posed a substantial stress on microbial development in the tailings. All treatments were dominated by typical extremophiles and lithotrophs, typically Truepera, Thiobacillus, Rubrobacter; significant increases in microbial diversity, biomass and frequency of organotrophic genera (typically Nocardioides and Altererythrobacter) were detected in the revegetated and amended treatment. We concluded that appropriate phytostabilization options have the potential to drive the microbial diversity and community structure in the tailings toward those of natural soils, however, inherent environmental stressors may limit such changes. PMID:26268667

  11. Impacts on Power Factor of AC Voltage Controllers Under Non-Sinusoidal Conditions

    Directory of Open Access Journals (Sweden)

    Mukhtiar Ahmed Mahar

    2012-04-01

    Full Text Available AC-AC conversion is obtained with the help of Cyclo-converters, DC Link converters and AC Voltage Controllers. AC voltage controllers are also referred to as voltage regulators. Main issue concerned to these converters is that they generate harmonics due to periodic variable structure system. The generated harmonics create disturbances and degrade the performance of converter. The power factor of supply side is affected due to these harmonics. This paper focuses on source side power factor of ac voltage controllers under nonsinusoidal conditions. In order to observe the power factor, measurement tool of power factor and simulation model of ac voltage controller is also developed in MATLAB software.

  12. Control to goal of cardiometabolic risk factors among Nigerians ...

    African Journals Online (AJOL)

    2011-07-12

    Jul 12, 2011 ... dyslipidemia, and obesity so as to minimize the development of ... Therapeutic goals used to define risk or poor control were values adopted by expert groups such as .... debated on a lot, the best approach to management still.

  13. CubeSat Form Factor Thermal Control Louvers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermal control of small spacecraft, including CubeSats, is a challenge for the next era of NASA spaceflight. Science objectives and components will still require...

  14. Patient related factors for optimal blood pressure control in patients ...

    African Journals Online (AJOL)

    EB

    2013-09-03

    Sep 3, 2013 ... Province, PR China. 3. School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2650, Australia. ... Board of our hospital, and written consent form ..... community-based case-control study in Singapore.

  15. Microbial control of varroa:misadventures in the field%瓦螨微生物防治的不良效果

    Institute of Scientific and Technical Information of China (English)

    罗莎林· 詹姆士; Hayes G

    2007-01-01

    We report six different field trials testing the efficacy of Metarhizium anisopliae,an entomopathogenic fungus,against varroa mites in honey bee hives.Varroa mites are parasitic on honey bees and cause serious damage to Apis mellifera colonies.Several control methods are available for varroa mites,none are very effective,so new,more effective methods are being sought.Varroa has previously been shown to be highly susceptible to M.anisopliae infections,and in our first two field trials,we found some efficacy from spore applications.However,in subsequent field trials,we were not able to obtain any varroa control, despite attempting several different application methods, two different strains of the fungus, and testing in different climates and during different phenological states of the honey bee colony. We conclude that microbial control of varroa using fungi is not likely to be effective unless some way is found to prolong the survival of the spores (or other infective units) in the hive environment.

  16. Case control study to identify risk factors for acute hepatitis C virus infection in Egypt

    National Research Council Canada - National Science Library

    Kandeel, Amr M; Talaat, Maha; Afifi, Salma A; El-Sayed, Nasr M; Abdel Fadeel, Moustafa A; Hajjeh, Rana A; Mahoney, Frank J

    2012-01-01

    .... We conducted a case-control study, June 2007-September 2008, to investigate risk factors for acute HCV infection in Egypt among 86 patients and 287 age and gender matched controls identified in two...

  17. Integrated effect of microbial antagonist, organic amendment and fungicide in controlling seedling mortality (Rhizoctonia solani) and improving yield in pea (Pisum sativum L.).

    Science.gov (United States)

    Akhter, Wasira; Bhuiyan, Mohamed Khurshed Alam; Sultana, Farjana; Hossain, Mohamed Motaher

    2015-01-01

    The study evaluated the comparative performance of a few microbial antagonists, organic amendments and fungicides and their integration for the management of seedling mortality (Rhizoctonia solani Kühn) and yield improvement in pea (Pisum sativum L.). Before setting the experiment in field microplots, a series of in vitro and in vivo experiments were conducted to select a virulent isolate of R. solani, an effective antagonistic isolate of Trichoderma harzianum, a fungitoxic organic amendment and an appropriate fungicide. A greenhouse pathogenicity test compared differences in seedling mortality in pea inoculated by four isolates of R. solani and identified the isolate RS10 as the most virulent one. Among the 20 isolates screened in dual culture assay on PDA, T. harzianum isolate T-3 was found to show the highest (77.22%) inhibition of the radial growth of R. solani. A complete inhibition (100.00%) of colony growth of R. solani was observed when fungicide Bavistin 50 WP and Provax-200 at the rate of 100 and 250 ppm, respectively, were used, while Provax-200 was found to be highly compatible with T. harzianum. Mustard oilcake gave maximum inhibition (60.28%) of the radial growth of R. solani at all ratios, followed by sesame oilcake and tea waste. Integration of soil treatment with T. harzianum isolate T-3 and mustard oilcake and seed treatment with Provax-200 appeared to be significantly superior in reducing seedling mortality and improving seed yield in pea in comparison to any single or dual application of them in the experimental field. The research results will help growers develop integrated disease management strategies for the control of Rhizoctonia disease in pea. The research results show the need for an integrating selective microbial antagonist, organic amendment and fungicide to achieve appropriate management of seedling mortality (R. solani) and increase of seed yield in pea. Copyright © 2014 Académie des sciences. Published by Elsevier SAS. All

  18. Synbiotic therapy decreases microbial translocation and inflammation and improves immunological status in HIV-infected patients: a double-blind randomized controlled pilot trial

    Directory of Open Access Journals (Sweden)

    González-Hernández Luz A

    2012-10-01

    Full Text Available Abstract Background HIV-infection results in damage and dysfunction of the gastrointestinal system. HIV enteropathy includes pronounced CD4+ T-cell loss, increased intestinal permeability, and microbial translocation that promotes systemic immune activation, which is implicated in disease progression. A synbiotic is the combination of probiotics and prebiotics that could improve gut barrier function. Our study goal was to determine whether the use of a synbiotic, probiotics or a prebiotic can recover immunological parameters in HIV-infected subjects through of a reduction of microbial translocation and pro-inflammatory cytokine production. Methods A randomized, double-blind controlled study was performed; twenty Antiretroviral treatment-naïve HIV-infected subjects were subgrouped and assigned to receive a synbiotic, probiotics, a prebiotic, or a placebo throughout 16 weeks. Results We had no reports of serious adverse-events. From baseline to week 16, the synbiotic group showed a reduction in bacterial DNA concentrations in plasma (p = 0.048. Moreover, the probiotic and synbiotic groups demonstrated a decrease in total bacterial load in feces (p = 0.05. The probiotic group exhibited a significant increment of beneficial bacteria load (such as Bifidobacterium; p = 0.05 and a decrease in harmful bacteria load (such as Clostridium; p = 0.063. In the synbiotic group, the CD4+ T-cells count increased (median: +102 cells/μL; p = 0.05 and the level of Interleukin 6 cytokine decreased significantly (p = 0.016. Conclusions Our study showed a significant increase in CD4+ T lymphocyte levels in the synbiotic group, which could delay the initiation of antiretroviral therapy and decrease costs in countries with limited resources.

  19. Wheat bran extract alters colonic fermentation and microbial composition, but does not affect faecal water toxicity: a randomised controlled trial in healthy subjects.

    Science.gov (United States)

    Windey, Karen; De Preter, Vicky; Huys, Geert; Broekaert, Willem F; Delcour, Jan A; Louat, Thierry; Herman, Jean; Verbeke, Kristin

    2015-01-28

    Wheat bran extract (WBE), containing arabinoxylan-oligosaccharides that are potential prebiotic substrates, has been shown to modify bacterial colonic fermentation in human subjects and to beneficially affect the development of colorectal cancer (CRC) in rats. However, it is unclear whether these changes in fermentation are able to reduce the risk of developing CRC in humans. The aim of the present study was to evaluate the effects of WBE on the markers of CRC risk in healthy volunteers, and to correlate these effects with colonic fermentation. A total of twenty healthy subjects were enrolled in a double-blind, cross-over, randomised, controlled trial in which the subjects ingested WBE (10 g/d) or placebo (maltodextrin, 10 g/d) for 3 weeks, separated by a 3-week washout period. At the end of each study period, colonic handling of NH3 was evaluated using the biomarker lactose[15N, 15N']ureide, colonic fermentation was characterised through a metabolomics approach, and the predominant microbial composition was analysed using denaturing gradient gel electrophoresis. As markers of CRC risk, faecal water genotoxicity was determined using the comet assay and faecal water cytotoxicity using a colorimetric cell viability assay. Intake of WBE induced a shift from urinary to faecal 15N excretion, indicating a stimulation of colonic bacterial activity and/or growth. Microbial analysis revealed a selective stimulation of Bifidobacterium adolescentis. In addition, WBE altered the colonic fermentation pattern and significantly reduced colonic protein fermentation compared with the run-in period. However, faecal water cytotoxicity and genotoxicity were not affected. Although intake of WBE clearly affected colonic fermentation and changed the composition of the microbiota, these changes were not associated with the changes in the markers of CRC risk.

  20. Tumor and Host Factors Controlling Antitumor Immunity and Efficacy of Cancer Immunotherapy.

    Science.gov (United States)

    Spranger, Stefani; Sivan, Ayelet; Corrales, Leticia; Gajewski, Thomas F

    2016-01-01

    Despite recent clinical advances in immunotherapy, a fraction of cancer patients fails to respond to these interventions. Evidence from preclinical mouse models as well as clinical samples has provided evidence that the extent of activated T cell infiltration within the tumor microenvironment is associated with clinical response to immunotherapies including checkpoint blockade. Therefore, understanding the molecular mechanisms mediating the lack of T cell infiltration into the tumor microenvironment will be instrumental for the development of new therapeutic strategies to render those patients immunotherapy responsive. Recent data have suggested that major sources of intersubject heterogeneity include differences in somatic mutations in specific oncogene pathways between cancers of individual subjects and also environmental factors including commensal microbial composition. Successful identification of such causal factors should lead to new therapeutic approaches that may facilitate T cell entry into noninflamed tumors and expand the fraction of patients capable of responding to novel immunotherapies.

  1. Investigation and control of factors influencing resistance upset butt welding.

    NARCIS (Netherlands)

    Kerstens, N.F.H.

    2010-01-01

    The purpose of this work is to investigate the factors influencing the resistance upset butt welding process to obtain an understanding of the metal behaviour and welding process characteristics, so that new automotive steels can be welded with reduced development time and fewer failures in

  2. Investigation and control of factors influencing resistance upset butt welding.

    NARCIS (Netherlands)

    Kerstens, N.F.H.

    2010-01-01

    The purpose of this work is to investigate the factors influencing the resistance upset butt welding process to obtain an understanding of the metal behaviour and welding process characteristics, so that new automotive steels can be welded with reduced development time and fewer failures in producti

  3. Controlled growth factor release from synthetic extracellular matrices

    Science.gov (United States)

    Lee, Kuen Yong; Peters, Martin C.; Anderson, Kenneth W.; Mooney, David J.

    2000-12-01

    Polymeric matrices can be used to grow new tissues and organs, and the delivery of growth factors from these matrices is one method to regenerate tissues. A problem with engineering tissues that exist in a mechanically dynamic environment, such as bone, muscle and blood vessels, is that most drug delivery systems have been designed to operate under static conditions. We thought that polymeric matrices, which release growth factors in response to mechanical signals, might provide a new approach to guide tissue formation in mechanically stressed environments. Critical design features for this type of system include the ability to undergo repeated deformation, and a reversible binding of the protein growth factors to polymeric matrices to allow for responses to repeated stimuli. Here we report a model delivery system that can respond to mechanical signalling and upregulate the release of a growth factor to promote blood vessel formation. This approach may find a number of applications, including regeneration and engineering of new tissues and more general drug-delivery applications.

  4. Factors Affccting Change of Microbial Community During Plant Residue Decomposition: A Review%植物残体分解过程中微生物群落变化影响因素研究进展

    Institute of Scientific and Technical Information of China (English)

    王晓玥; 孙波

    2012-01-01

    Plant residues are an important source of soil organic matter. An increasing attention has been paid on the succession^ pattern of microbial community structure during decomposition of plant residues. In this article, it is reviewed factors that have significant influence on the microbial community structure and function. These factors mainly include properties of plant residue, soil and climate factors and agricultural practices, which affect diversity of microbial community through influences on both activities of microbe and chemical composition changes of plant residue during its decomposition process. The impacts of these factors are not isolated, but interrelated and conditioned. In addition, microbial communities have shown obvious patterns with decomposition of residues. Furthermore, profoundly researches, especially under field conditions, are needed on successional pattern of key microbial community as well as interaction mechanism of different factors.%植物残体是土壤有机质的重要来源,研究分解植物残体的微生物群落结构及其演替规律日益受到重视.本文综述了影响植物残体分解过程中微生物群落结构和功能变化的3个主要因素;植物残体的性质、土壤和气候环境因素、农艺措施,这些因素通过影响微生物本身的活性和植物残体分解过程中化学组成的变化从而导致微生物群落的变化,同时植物残体腐解过程中微生物群落存在明显的演替现象.以上因素的影响并不是孤立的,而是相互联系和制约的.未来针对野外田问条件下植物残体的分解过程,仍需深入研究关键微生物群落的演替规律以及不同影响因素的交互作用机制.

  5. Control of wastewater N2O emissions by balancing the microbial communities using a fuzzy-logic approach

    DEFF Research Database (Denmark)

    Boiocchi, Riccardo; Gernaey, Krist; Sin, Gürkan

    2016-01-01

    In this work, a fuzzy-logic controller for minimization of the nitrous oxide emission from wastewater treatment plants is developed and tested in a simulation environment. The controller is designed in order to maintain a balance between production and consumption of nitrite by AOB and NOB...

  6. Poor stroke-related risk factor control even after stroke: an opportunity for rehabilitation professionals.

    Science.gov (United States)

    Ellis, Charles; Breland, Hazel L

    2014-01-01

    The burden of chronic disease worldwide is substantial. Unfortunately, risk factor control for most chronic diseases remains poor even after diagnoses. This is a major concern because poor risk factor control often leads to secondary consequences of the disease and the development of co-existing diseases. Stroke is a chronic condition that frequently requires the services of rehabilitation professionals who can also play an important role in risk factor management to reduce recurrent stroke. Approaches to the management of stroke risk factors in stroke survivors vary greatly and consequently outcomes vary in a similar fashion. The current literature suggests that uniform offering of structured risk factor control programs over time to individuals with chronic disease can improve knowledge of stroke risk factors, knowledge of action to control risk factors and in turn facilitate self-management practices that reduce the negative consequences of chronic diseases. Rehabilitation professionals can play a vital role in the management and secondary prevention of chronic diseases during the rehabilitation process via patient education and training. Implications for Rehabilitation Evidence suggests that risk factor control remains poor in many individuals with chronic conditions such as stroke. Rehabilitation professionals can play a key role in programs designed to improve risk factor control in chronic conditions. Future risk factor control programs can be structured and implemented over time to include rehabilitation professionals.

  7. Inhibition of microbial growth on air cathodes of single chamber microbial fuel cells by incorporating enrofloxacin into the catalyst layer.

    Science.gov (United States)

    Liu, Weifeng; Cheng, Shaoan; Sun, Dan; Huang, Haobin; Chen, Jie; Cen, Kefa

    2015-10-15

    The inevitable growth of aerobic bacteria on the surface of air cathodes is an important factor reducing the performance stability of air cathode single-chamber membrane-free microbial fuel cells (MFCs). Thus searching for effective methods to inhibit the cathodic microbial growth is critical for the practical application of MFCs. In this study, enrofloxacin (ENR), a broad spectrum fluoroquinolone antibiotic, was incorporated into the catalyst layer of activated carbon air cathodes (ACACs) to inhibit the cathodic microbial growth. The biomass content on ACACs was substantially reduced by 60.2% with ENR treatment after 91 days of MFCs operation. As a result of the inhibited microbial growth, the oxygen reduction catalytic performance of the ENR treated ACACs was much stable compared to the fast performance decline of the untreated control. Consequently, a quite stable electricity production was obtained for the MFCs with the ENR treated ACACs, in contrast with a 22.5% decrease in maximum power density of the MFCs with the untreated cathode. ENR treatment of ACACs showed minimal effects on the anode performance. These results indicate that incorporating antibiotics into ACACs should be a simple and effective strategy to inhibit the microbial growth and improve the long-term stability of the performance of air cathode and the electricity production of MFCs.

  8. 北海市海产品微生物污染及其影响因素调查%Investigation on microbial contamination of seafood and its influencing factors in Beihai City

    Institute of Scientific and Technical Information of China (English)

    曾小峰; 吴德仁; 陈坚磊; 刘斌

    2012-01-01

    目的 了解北海市海产品微生物污染状况,探讨影响不同类型海产品、不同食用人群的环节和主要影响因素.方法 对该市销售量较大的海产鱼类、软体类和甲壳类共3类18种海产品,计120份样品进行采样和微生物检测;收集、核实近5年以来本市辖区内食源性疾病次数进行比对分析.结果 调查120份海产品,在检测6种相关微生物中仅检出副溶血性弧菌19份,检出率为15.8%.其中软体类、甲壳类和海水鱼类中的检出率分别为16.7%、16.2%和14.6%.不同处理方式的海产品中新鲜的检出率最高(21.5%),其次为冰冻的(18.5%),干货则未检出,差异有统计学意义(X2=6.99,P<0.05).该市近5年食物中毒69起,以细菌性为主(43起),而其中因副溶血性弧菌引起的有26起(60.5%).结论 该市的海产品一定程度上受到副溶血性弧菌污染,新鲜的软体类海产品属于微生物污染高危海产品种类,应开展深入的污染控制研究和加强必要的监管.%[Objective] To understand the status of microbial contamination in seafood in Beihai City, explore the main influencing factors of different types of seafood and populations. [Methods] 120 samples were collected from 3 types of 18 kinds of seafood which included marine fishes, mollusks and crustaceans, and were detected for microbial contamination. The data of food-borne diseases in Beihai city in the last 5 years were collected and verified, and a comparative analysis were conducted. [ Results ] 120 seafood samples were detected for 6 kinds of related microorganisms, and vibrio parahaemolyticus was found in 19 samples with the detection rate of IS. 8%. The detection rate of mollusks, crustaceans and marine fishes was respectively 16. 7% , 16. 2% and 14.6%. Among different treatment methods, the detection rate of fresh samples was the highest (21.5% ), followed by the frozen samples (18.5% ) , vibrio parahaemolyticus was not detected in dry

  9. Regulated assembly of transcription factors and control of transcription initiation.

    Science.gov (United States)

    Beckett, D

    2001-11-30

    Proteins that function in regulation of transcription initiation are typically homo or hetero-oligomeric. Results of recent biophysical studies of transcription regulators indicate that the assembly of these proteins is often subject to regulation. This regulation of assembly dictates the frequency of transcription initiation via its influence on the affinity of a transcription regulator for DNA and its affect on target site selection. Factors that modulate transcription factor assembly include binding of small molecules, post-translational modification, DNA binding and interactions with other proteins. Here, the results of recent structural and/or thermodynamic studies of a number of transcription regulators that are subject to regulated assembly are reviewed. The accumulated data indicate that this phenomenon is ubiquitous and that mechanisms utilized in eukaryotes and prokaryotes share common features. Copyright 2001 Academic Press.

  10. Polyketide chain length control by chain length factor.

    Science.gov (United States)

    Tang, Yi; Tsai, Shiou-Chuan; Khosla, Chaitan

    2003-10-22

    Bacterial aromatic polyketides are pharmacologically important natural products. A critical parameter that dictates product structure is the carbon chain length of the polyketide backbone. Systematic manipulation of polyketide chain length represents a major unmet challenge in natural product biosynthesis. Polyketide chain elongation is catalyzed by a heterodimeric ketosynthase. In contrast to homodimeric ketosynthases found in fatty acid synthases, the active site cysteine is absent from the one subunit of this heterodimer. The precise role of this catalytically silent subunit has been debated over the past decade. We demonstrate here that this subunit is the primary determinant of polyketide chain length, thereby validating its designation as chain length factor. Using structure-based mutagenesis, we identified key residues in the chain length factor that could be manipulated to convert an octaketide synthase into a decaketide synthase and vice versa. These results should lead to novel strategies for the engineered biosynthesis of hitherto unidentified polyketide scaffolds.

  11. Addressing the human factors issues associated with control room modifications

    Energy Technology Data Exchange (ETDEWEB)

    O`Hara, J.; Stubler, W. [Brookhaven National Lab., Upton, NY (United States). Dept. of Advanced Technology; Kramer, J. [Nuclear Regulatory Commission, Washington, DC (United States). Office of Nuclear Regulatory Research

    1998-03-01

    Advanced human-system interface (HSI) technology is being integrated into existing nuclear plants as part of plant modifications and upgrades. The result of this trend is that hybrid HSIs are created, i.e., HSIs containing a mixture of conventional (analog) and advanced (digital) technology. The purpose of the present research is to define the potential effects of hybrid HSIs on personnel performance and plant safety and to develop human factors guidance for safety reviews of them where necessary. In support of this objective, human factors issues associated with hybrid HSIs were identified. The issues were evaluated for their potential significance to plant safety, i.e., their human performance concerns have the potential to compromise plant safety. The issues were then prioritized and a subset was selected for design review guidance development.

  12. Environmental factors controlling methane emissions from peatlands in northern Minnesota

    Science.gov (United States)

    Dise, Nancy B.; Gorham, Eville; Verry, Elon S.

    1993-01-01

    The environmental factors affecting the emission of methane from peatlands were investigated by correlating CH4 emission data for two years, obtained from five different peatland ecosystems in northern Minnesota, with peat temperature, water table position, and degree of peat humification. The relationship obtained between the CH4 flux and these factors was compared to results from a field manipulation experiment in which the water table was artificially raised in three experimental plots within the driest peatland. It was found that peat temperature, water table position, and degree of peat humification explained 91 percent of the variance in log CH4 flux, successfully predicted annual CH4 emission from individual wetlands, and predicted the change in flux due to the water table manipulation. Raising the water table in the bog corrals by an average of 6 cm in autumn 1989 and 10 cm in summer 1990 increased CH4 emission by 2.5 and 2.2 times, respectively.

  13. Enhanced imaging of DNA via active quality factor control

    Science.gov (United States)

    Humphris, A. D. L.; Round, A. N.; Miles, M. J.

    2001-10-01

    Adsorption processes at single molecule level are of fundamental importance for the understanding and development of biomaterials. Atomic force microscopy (AFM) has played a critical role in this field due to its high resolution and ability to image in a liquid environment. We present a method that improves the dynamic force sensitivity and the resolution of a conventional AFM. This is achieved via a positive feedback loop that enhances the effective quality factor of the cantilever in a liquid environment to values in excess of 300, compared to a nominal value of ˜1. This active quality factor enhancement has been used to image DNA and an increase in the height of the molecule observed.

  14. Optimal replicator factor control in wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    For TDMA MAC protocols in wireless sensor networks (WSNs), redundancy and retransmission are two important methods to provide high end-to-end transmission reliability. Since reliable transmissions will lead to more energy consumption, there exists an intrinsic tradeoff between transmission reliability and energy efficiency. For each link, we name the number of its reserved time slots in each MAC superframe as a replicator factor. In the following paper, we propose a reliability-lifetime tradeoff framework (...

  15. Well productivity controlling factors in crystalline terrains of southeastern Brazil

    Science.gov (United States)

    Neves, Mirna A.; Morales, Norberto

    2007-05-01

    Over the last decades, increasing water demands have fostered research to obtain high well yields in crystalline terrains where, besides the intrinsic properties of rocks, the groundwater flow depends on several factors. The depth of the wells, the lithotypes, the presence and thickness of sedimentary coverings and weathered layers, the landforms, the geological structures, and the effects of tectonic stresses are among the most investigated factors considered as determinant of well productivity. The influence of these factors on productivity of wells that exploit the Crystalline Aquifer System in the Jundiaí River Catchment, southeastern Brazil, is investigated in this work. The largest region of the studied area is located on the Precambrian Basement, partially covered by sedimentary deposits. The results show that the sedimentary deposits and the weathered layer are important for high well yield, but it also depends on the existence of a net of open fractures, in order to maintain high productivity. The sites that have more possibility of occurrence of such structures are the regional shear and fault zones and other minor structures with NW-SE and E-W directions, which characterize areas subjected to transtensional stress related to the neotectonics.

  16. Microbial properties of soil aggregates created by earthworms and other factors: spherical and prismatic soil aggregates from unreclaimed post-mining sites.

    Science.gov (United States)

    Frouz, J; Krištůfek, V; Livečková, M; van Loo, D; Jacobs, P; Van Hoorebeke, L

    2011-01-01

    Soil aggregates between 2 and 5 mm from 35- and 45-year-old unreclaimed post-mining sites near Sokolov (Czech Republic) were divided into two groups: spherical and prismatic. X-ray tomography indicated that prismatic aggregates consisted of fragments of claystone bonded together by amorphous clay and roots while spherical aggregates consisted of a clay matrix and organic fragments of various sizes. Prismatic aggregates were presumed to be formed by plant roots and physical processes during weathering of Tertiary mudstone, while earthworms were presumed to contribute to the formation of spherical aggregates. The effects of drying and rewetting and glucose addition on microbial respiration, microbial biomass, and counts of bacteria in these aggregates were determined. Spherical aggregates contained a greater percentage of C and N and a higher C-to-N ratio than prismatic ones. The C content of the particulate organic matter was also higher in the spherical than in the prismatic aggregates. Although spherical aggregates had a higher microbial respiration and biomass, the growth of microbial biomass in spherical aggregates was negatively correlated with initial microbial biomass, indicating competition between bacteria. Specific respiration was negatively correlated with microbial biomass. Direct counts of bacteria were higher in spherical than in prismatic aggregates. Bacterial numbers were more stable in the center than in the surface layers of the aggregates. Transmission electron microscopy indicated that bacteria often occurred as individual cells in prismatic aggregates but as small clusters of cells in spherical aggregates. Ratios of colony forming units (cultivatable bacteria) to direct counts were higher in spherical than in prismatic aggregates. Spherical aggregates also contained faster growing bacteria.

  17. Microbial properties of soil aggregates created by earthworms and other factors: spherical and prismatic soil aggregates from unreclaimed post-mining sites

    Energy Technology Data Exchange (ETDEWEB)

    Frouz, J.; Kristufek, V.; Liveckova, M.; van Loo, D.; Jacobs, P.; Van Hoorebeke, L. [Charles University of Prague, Prague (Czech Republic). Inst. of Environmental Studies

    2011-01-15

    Soil aggregates between 2 and 5 mm from 35- and 45-year-old unreclaimed post-mining sites near Sokolov (Czech Republic) were divided into two groups: spherical and prismatic. X-ray tomography indicated that prismatic aggregates consisted of fragments of claystone bonded together by amorphous clay and roots while spherical aggregates consisted of a clay matrix and organic fragments of various sizes. Prismatic aggregates were presumed to be formed by plant roots and physical processes during weathering of Tertiary mudstone, while earthworms were presumed to contribute to the formation of spherical aggregates. The effects of drying and rewetting and glucose addition on microbial respiration, microbial biomass, and counts of bacteria in these aggregates were determined. Spherical aggregates contained a greater percentage of C and N and a higher C-to-N ratio than prismatic ones. The C content of the particulate organic matter was also higher in the spherical than in the prismatic aggregates. Although spherical aggregates had a higher microbial respiration and biomass, the growth of microbial biomass in spherical aggregates was negatively correlated with initial microbial biomass, indicating competition between bacteria. Specific respiration was negatively correlated with microbial biomass. Direct counts of bacteria were higher in spherical than in prismatic aggregates. Bacterial numbers were more stable in the center than in the surface layers of the aggregates. Transmission electron microscopy indicated that bacteria often occurred as individual cells in prismatic aggregates but as small clusters of cells in spherical aggregates. Ratios of colony forming units (cultivatable bacteria) to direct counts were higher in spherical than in prismatic aggregates. Spherical aggregates also contained faster growing bacteria.

  18. Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids: Part II. Effects on intestinal histology and active nutrient transport.

    Science.gov (United States)

    Walsh, M C; Rostagno, M H; Gardiner, G E; Sutton, A L; Richert, B T; Radcliffe, J S

    2012-08-01

    The objective of this study was to evaluate the effects of water-delivered, direct-fed microbials (DFM) or organic acids on intestinal morphology and active nutrient absorption in weanling pigs after deliberate Salmonella infection. Pigs (n = 88) were weaned at 19 ± 2 d of age and assigned to 1 of the following treatments, which were administered for 14 d: 1) control diet; 2) control diet + DFM (Enterococcus faecium, Bacillus subtilis, and Bacillus licheniformis) in drinking water at 10(9) cfu/L for each strain of bacteria; 3) control diet + organic acid-based blend (predominantly propionic, acetic, and benzoic acids) in drinking water at 2.58 mL/L; and 4) control diet + 55 mg/kg carbadox. Pigs were challenged with 10(10) cfu Salmonella enterica var Typhimurium 6 d after commencement of treatments. Pigs (n = 22/d) were harvested before Salmonella challenge and on d 2, 4, and 8 after challenge. Duodenal, jejunal, and ileal mucosal tissues were sampled for measurement of villus height and crypt depth. Jejunal tissue was sampled for determination of active nutrient absorption in modified Ussing chambers. Duodenal villus height was greater in pigs fed in-feed antibiotic before infection (P Salmonella infection resulted in a linear decrease in phosphorus (P Salmonella infection reduced basal short-circuit current (I(sc)); however, water-delivered DFM or organic acid treatments caused greater basal I(sc) on d 2 after challenge than did carbadox. Carbachol-induced chloride ion secretion was greatest in negative control pigs before infection (P < 0.01) and DFM-treated pigs (P < 0.05) after infection. In conclusion, both the DFM and acidification treatments induced increases in basal active ion movement and jejunal crypt depth, which could be interpreted as responses consistent with increased Salmonella pathology, but none of the additives markedly affected intestinal absorptive and secretory function in response to Salmonella challenge.

  19. Control of Fe(III) site occupancy on the rate and extent of microbial reduction of Fe(III) in nontronite

    Science.gov (United States)

    Jaisi, D.P.; Kukkadapu, R.K.; Eberl, D.D.; Dong, H.

    2005-01-01

    A quantitative study was performed to understand how Fe(III) site occupancy controls Fe(III) bioreduction in nontronite by Shewanella putrefaciens CN32. NAu-1 and NAu-2 were nontronites and contained Fe(III) in different structural sites with 16 and 23% total iron (w/w), respectively, with almost all iron as Fe(III). Mo??ssbauer spectroscopy showed that Fe(III) was present in the octahedral site in NAu-1 (with a small amount of goethite), but in both the tetrahedral and the octahedral sites in NAu-2. Mo??ssbauer data further showed that the octahedral Fe(III) in NAu-2 existed in at least two environments- trans (M1) and cis (M2) sites. The microbial Fe(III) reduction in NAu-1 and NAu-2 was studied in batch cultures at a nontronite concentration of 5 mg/mL in bicarbonate buffer with lactate as the electron donor. The unreduced and bioreduced nontronites were characterized by X-ray diffraction (XRD), Mo??ssbauer spectroscopy, and transmission electron microscopy (TEM). In the presence of an electron shuttle, anthraquinone-2,6-disulfonate (AQDS), the extent of bioreduction was 11%-16% for NAu-1 but 28%-32% for NAu-2. The extent of reduction in the absence of AQDS was only 5%-7% for NAu-1 but 14%-18% for NAu-2. The control experiments with heat killed cells and without cells did not show any appreciable reduction (crystal size distribution. The decrease in crystal size suggests reductive dissolution of nontronite NAu-2, which was supported by aqueous solution chemistry (i.e., aqueous Si). These data suggest that the more extensive Fe(III) bioreduction in NAu-2 was due to the presence of the tetrahedral and the trans-octahedral Fe(III), which was presumed to be more reducible. The biogenic Fe(II) was not associated with biogenic solids or in the aqueous solution. We infer that it may be either adsorbed onto surfaces of nontronite particles/bacteria or in the structure of nontronite. Furthermore, we have demonstrated that natural nontronite clays were capable of

  20. Factors controlling vertical fluxes of prrticles in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, T.M.B.; Ramaswamy, V.; Parthiban, G.; Shankar, R.

    in the mixed layer depth which, in turn, is controlled by the strength of the Findlater Jet and the curl of the wind stress. The increase in biogenic silica fluxes during the late SW monsoon is related to the advection of nutrient-rich water from the Oman...

  1. Factors Contributing to Self Control for Incarcerated Youth

    Science.gov (United States)

    Winquist, Trancita

    2010-01-01

    This study was conducted to examine characteristics contributing to high self control for incarcerated youth. Subjects include fifty youth (8 females and 42 males) ages 14 through 18 incarcerated for at least 60 days. Data on subjects' responses from a validated measure (Grasmick et. al. Scale, 1993) and data from historical records, STAR reading…

  2. Evaluation of the surgical factor in postoperative pain control

    Directory of Open Access Journals (Sweden)

    Shams Mohamed

    2010-01-01

    Full Text Available Background: Postoperative pain control has been studied extensively, including many perioperative pain control procedures. Unfortunately, the impact of the surgical technique was not objectively studied. Aim: The aim of this study is to evaluate if the type of surgical dissection needed for extensive abdominal wall dissection actually has an effect in the reduction of postoperative pain or not. Materials and Methods: Forty adult patients, 19 males and 21 females, were randomly divided into two groups with each group containing 20 patients having different varieties of anterior abdominal wall ventral hernia. Patients in group I had their hernias and abdominal wall flaps dissected by only sharp dissection using scalpel. Patients in group II had their hernias and abdominal wall flaps dissected using mainly blunt dissection assisted by sharp dissection where blunt dissection could not do the job. All the patients had general anesthesia. No preemptive analgesia was used. Nalbufen was used as the only postoperative pain killer and the total amount used of it was treated as the indicator for the intensity of postoperative pain. Results: The results of the present study showed that the total amount of Nalbufen used for the control of postoperative pain is significantly less in group I throughout the postoperative follow-up period. Conclusion: This study concludes that use of sharp dissection in cases of extensive abdominal wall dissection is statistically better than other methods of dissection in terms of postoperative pain control.

  3. Factors Relating to Staff Attributions of Control over Challenging Behaviour

    Science.gov (United States)

    Dilworth, Jennifer A.; Phillips, Neil; Rose, John

    2011-01-01

    Background: Previous research has suggested that severity of intellectual disability (ID) and topography of behaviour may influence staff causal attributions regarding challenging behaviour. Subsequently, these causal attributions may influence helping behaviours. This study investigated the relationship between attributions of control over…

  4. Resource Form Factor and Installation of GFA Controllers

    Energy Technology Data Exchange (ETDEWEB)

    DeSteese, John G.; Hammerstrom, Donald J.

    2009-11-15

    The focus of this task is to optimize the form and placement of a controller comprising the Grid Friendly™ appliance (GFA) controller, power supply and power relay (and/or a solid-state power electronic switch) that would command a domestic water heater to shed its load in response to stress on the electric power grid. The GFA controller would disconnect the water heater from its supply circuit whenever it senses a low voltage signal or other indicators of system stress communicated via the electric power distribution system. Power would be reconnected to the appliance when the GFA controller senses the absence of these signals. This project has also considered more frequent cycling of this controller’s relay switch to perform demand-side frequency regulation. The principal criteria considered in this optimization are reliability, cost and life expectancy of the GFA components. The alternative embodiments of the GFA equipment under consideration are: Option 1- installation inside the insulation space of the water heater between the tank and jacket Option 2 containment in a separate nearby electrical enclosure Option 3 - as a modification or adjunct to the distribution panel housing and/or the breaker that protects the water heater supply circuit.

  5. Evaluation of factors affecting adherence to asthma controller ...

    African Journals Online (AJOL)

    The adherence to asthma treatment was rated using Morisky Medication Adherence Scale. A ... The prevalence of low adherence rate to asthma controller therapy was 44.8% and the absence of any .... Obesity (BMI ≥ 30 kg/m2). No. Yes.

  6. Microbial reduction of iodate

    Science.gov (United States)

    Councell, T.B.; Landa, E.R.; Lovley, D.R.

    1997-01-01

    The different oxidation species of iodine have markedly different sorption properties. Hence, changes in iodine redox states can greatly affect the mobility of iodine in the environment. Although a major microbial role has been suggested in the past to account for these redox changes, little has been done to elucidate the responsible microorganisms or the mechanisms involved. In the work presented here, direct microbial reduction of iodate was demonstrated with anaerobic cell suspensions of the sulfate reducing bacterium Desulfovibrio desulfuricans which reduced 96% of an initial 100 ??M iodate to iodide at pH 7 in 30 mM NaHCO3 buffer, whereas anaerobic cell suspensions of the dissimilatory Fe(III)-reducing bacterium Shewanella putrefaciens were unable to reduce iodate in 30 mM NaHCO3 buffer (pH 7). Both D. desulfuricans and S. putrefaciens were able to reduce iodate at pH 7 in 10 mM HEPES buffer. Both soluble ferrous iron and sulfide, as well as iron monosulfide (FeS) were shown to abiologically reduce iodate to iodide. These results indicate that ferric iron and/or sulfate reducing bacteria are capable of mediating both direct, enzymatic, as well as abiotic reduction of iodate in natural anaerobic environments. These microbially mediated reactions may be important factors in the fate and transport of 129I in natural systems.

  7. Microbial Risk Assessment

    Science.gov (United States)

    Ott, C. M.; Mena, K. D.; Nickerson, C.A.; Pierson, D. L.

    2009-01-01

    Historically, microbiological spaceflight requirements have been established in a subjective manner based upon expert opinion of both environmental and clinical monitoring results and the incidence of disease. The limited amount of data, especially from long-duration missions, has created very conservative requirements based primarily on the concentration of microorganisms. Periodic reevaluations of new data from later missions have allowed some relaxation of these stringent requirements. However, the requirements remain very conservative and subjective in nature, and the risk of crew illness due to infectious microorganisms is not well defined. The use of modeling techniques for microbial risk has been applied in the food and potable water industries and has exceptional potential for spaceflight applications. From a productivity standpoint, this type of modeling can (1) decrease unnecessary costs and resource usage and (2) prevent inadequate or inappropriate data for health assessment. In addition, a quantitative model has several advantages for risk management and communication. By identifying the variable components of the model and the knowledge associated with each component, this type of modeling can: (1) Systematically identify and close knowledge gaps, (2) Systematically identify acceptable and unacceptable risks, (3) Improve communication with stakeholders as to the reasons for resource use, and (4) Facilitate external scientific approval of the NASA requirements. The modeling of microbial risk involves the evaluation of several key factors including hazard identification, crew exposure assessment, dose-response assessment, and risk characterization. Many of these factors are similar to conditions found on Earth; however, the spaceflight environment is very specialized as the inhabitants live in a small, semi-closed environment that is often dependent on regenerative life support systems. To further complicate modeling efforts, microbial dose

  8. Reactor performances and microbial communities of biogas reactors: effects of inoculum sources.

    Science.gov (United States)

    Han, Sheng; Liu, Yafeng; Zhang, Shicheng; Luo, Gang

    2016-01-01

    Anaerobic digestion is a very complex process that is mediated by various microorganisms, and the understanding of the microbial community assembly and its corresponding function is critical in order to better control the anaerobic process. The present study investigated the effect of different inocula on the microbial community assembly in biogas reactors treating cellulose with various inocula, and three parallel biogas reactors with the same inoculum were also operated in order