Sample records for surface microbial contamination

  1. Metagenomes of Microbial Communities in Arsenic- and Pathogen-Contaminated Well and Surface Water from Bangladesh

    PubMed Central

    Layton, Alice C.; Chauhan, Archana; Williams, Daniel E.; Mailloux, Brian; Knappett, Peter S. K.; Ferguson, Andrew S.; McKay, Larry D.; Alam, M. Jahangir; Matin Ahmed, Kazi; van Geen, Alexander

    2014-01-01

    The contamination of drinking water from both arsenic and microbial pathogens occurs in Bangladesh. A general metagenomic survey of well water and surface water provided information on the types of pathogens present and may help elucidate arsenic metabolic pathways and potential assay targets for monitoring surface-to-ground water pathogen transport. PMID:25414497

  2. Metagenomes of microbial communities in arsenic- and pathogen-contaminated well and surface water from bangladesh.

    PubMed

    Layton, Alice C; Chauhan, Archana; Williams, Daniel E; Mailloux, Brian; Knappett, Peter S K; Ferguson, Andrew S; McKay, Larry D; Alam, M Jahangir; Matin Ahmed, Kazi; van Geen, Alexander; Sayler, Gary S

    2014-01-01

    The contamination of drinking water from both arsenic and microbial pathogens occurs in Bangladesh. A general metagenomic survey of well water and surface water provided information on the types of pathogens present and may help elucidate arsenic metabolic pathways and potential assay targets for monitoring surface-to-ground water pathogen transport. PMID:25414497

  3. MICROFRACTURE SURFACE GEOCHEMISTRY AND ADHERENT MICROBIAL POPULATION METABOLISM IN TCE-CONTAMINATED COMPETENT BEDROCK

    EPA Science Inventory

    A TCE-contaminated competent bedrock site in Portsmouth, NH was used to determine if a relation existed between microfracture (MF) surface geochemistry and the ecology and metabolic activity of attached microbes relative to terminal electron accepting processes (TEAPs) and TCE bi...

  4. Microbial populations in contaminant plumes

    NASA Astrophysics Data System (ADS)

    Haack, Sheridan K.; Bekins, Barbara A.

    Efficient biodegradation of subsurface contaminants requires two elements: (1) microbial populations with the necessary degradative capabilities, and (2) favorable subsurface geochemical and hydrological conditions. Practical constraints on experimental design and interpretation in both the hydrogeological and microbiological sciences have resulted in limited knowledge of the interaction between hydrogeological and microbiological features of subsurface environments. These practical constraints include: (1) inconsistencies between the scales of investigation in the hydrogeological and microbiological sciences, and (2) practical limitations on the ability to accurately define microbial populations in environmental samples. However, advances in application of small-scale sampling methods and interdisciplinary approaches to site investigations are beginning to significantly improve understanding of hydrogeological and microbiological interactions. Likewise, culture-based and molecular analyses of microbial populations in subsurface contaminant plumes have revealed significant adaptation of microbial populations to plume environmental conditions. Results of recent studies suggest that variability in subsurface geochemical and hydrological conditions significantly influences subsurface microbial-community structure. Combined investigations of site conditions and microbial-community structure provide the knowledge needed to understand interactions between subsurface microbial populations, plume geochemistry, and contaminant biodegradation. La biodégradation efficace des polluants souterrains requiert deux éléments: des populations microbiennes possédant les aptitudes nécessaires à la dégradation, et des conditions géochimiques et hydrologiques souterraines favorables. Des contraintes pratiques sur la conception et l'interprétation des expériences à la fois en microbiologie et en hydrogéologie ont conduit à une connaissance limitée des interactions entre les phénomènes hydrogéologiques et microbiologiques des environnements souterrains. Ces contraintes pratiques sont dues à des contradictions entre les échelles d'étude de l'hydrogéologie et de la microbiologie et à des limitations pratiques sur la capacitéà définir avec précision les populations microbiennes dans les échantillons. Cependant, des progrès dans l'application de méthodes d'échantillonnage à l'échelle locale et des approches pluridisciplinaires des études de terrain ont commencéà améliorer de façon significative notre compréhension des interactions hydrogéologiques et microbiologiques. De plus, les analyses moléculaires et sur les cultures des populations microbiennes présentes dans les panaches de pollution souterraine ont mis en évidence une adaptation significative de ces populations aux conditions environnementales du panache. Les résultats d'études récentes laissent penser que la variabilité des conditions géochimiques et hydrologiques souterraines influence significativement la structure des communautés microbiennes souterraines. Des recherches combinées sur les conditions de terrain et sur la structure des communautés microbiennes apportent les informations nécessaires à la compréhension des interactions entre les populations microbiennes souterraines, la géochimie du panache et la biodégradation du polluant. Para que la biodegradación de los contaminantes en el subsuelo sea eficiente se requiere: (1) una población microbiana con capacidad de degradación y (2) unas condiciones hidrológicas y geoquímicas favorables. Las restricciones de tipo práctico en los diseños y la interpretación de experimentos, tanto hidrogeológicos como microbiológicos, han dado lugar a un conocimiento limitado de la interrelación entre estas dos ciencias por lo que respecta al subsuelo. Estas restricciones incluyen: (1) inconsistencias entre las escalas de investigación en ambas ciencias (hidrogeología y microbiología) y (2) limitaciones prácticas para definir poblaciones microbianas en las muestras. Sin embargo, lo

  5. Rhizosphere microbial populations in contaminated soils

    Microsoft Academic Search

    T. D. Nichols; D. C. Wolf; H. B. Rogers; C. A. Beyrouty; C. M. Reynolds

    1997-01-01

    Rhizosphere microbial populations may increase bioremediation of soil contaminated with organic chemicals. A growth chamber\\u000a study was conducted to evaluate rhizosphere microbial populations in contaminated and non-contaminated soil. Alfalfa (Medicago sativa L.) and alpine bluegrass (Poa alpina L.) were grown in soil containing a mixture of organic chemicals for 14 weeks. The equal millimolar mixture of hexadecane,\\u000a (2,2-dimethylpropyl)benzene, cis-decahydronaphthalene (decalin),

  6. RHIZOSPHERE MICROBIAL POPULATIONS IN CONTAMINATED SOILS

    Microsoft Academic Search

    T. D. NICHOLS; D. C. WOLF; H. B. ROGERS; C. A. BEYROUTY; C. M. REYNOLDS

    1997-01-01

    Rhizosphere microbial populations may increase bioremediation of soil contaminated with organic chemicals. A growth chamber study was conducted to evaluate rhizosphere microbial populations in contaminated and non-contaminated soil. Alfalfa (Medicago sativa L.) and alpine bluegrass (Poa alpina L.) were grown in soil containing a mixture of organic chemicals for 14 weeks. The equal millimolar mixture of hexadecane, (2,2-dimethyl-propyl)-benzene, cis-decahydronaphthalene (decalin),

  7. Comparative plant uptake and microbial degradation of trichloroethylene in the rhizospheres of five plant species-- implications for bioremediation of contaminated surface soils

    SciTech Connect

    Anderson, T.A. (Tennessee Univ., Knoxville, TN (United States)); Walton, B.T. (Oak Ridge National Lab., TN (United States))

    1992-01-01

    The objective of this study was to collect data that would provide a foundation for the concept of using vegetation to enhance in situ bioremediation of contaminated surface soils. Soil and vegetation (Lespedeza cuneata, Paspalum notatum, Pinus taeda, and Solidago sp.) samples from the Miscellaneous Chemicals Basin (MCB) at the Savannah River Site were used in tests to identify critical plant and microbiological variables affecting the fate of trichloroethylene (TCE) in the root zone. Microbiological assays including phospholipid acid analyses, and {sup 14}C-acetate incorporation were conducted to elucidate differences in rhizosphere and nonvegetated soil microbial communities from the MCB. The microbial activity, biomass, and degradation of TCE in rhizosphere soils were significantly greater than corresponding nonvegetated soils. Vegetation had a positive effect on microbial degradation of {sup 14}C-TCE in whole-plant experiments. Soils from the MCB containing Lespedeza cuneata, Pinus taeda, and Glycine max mineralized greater than 25% of the {sup 14}C- TCE added compared with less than 20% in nonvegetated soils. Collectively, these results provide evidence for the positive role of vegetation in enhancing biodegradation.

  8. Microbial ecology of a crude oil contaminated aquifer

    USGS Publications Warehouse

    Bekins, B.A.; Cozzarelli, I.M.; Warren, E.; Godsy, E.M.

    2002-01-01

    Detailed microbial analyses of a glacial outwash aquifer contaminated by crude oil provide insights into the pattern of microbial succession from iron reducing to methanogenic in the anaerobic portion of the contaminant plume. We analysed sediments from this area for populations of aerobes, iron reducers, fermenters and methanogens, using the most probable number method. On the basis of the microbial data the anaerobic area can be divided into distinct physiological zones dominated by either iron-reducers or a consortium of fermenters and methanogens. Chemistry and permeability data show that methanogenic conditions develop first in areas of high hydrocarbon flux. Thus, we find methanogens both in high permeability horizons and also where separate-phase crude oil is present in either the saturated or unsaturated zone. Microbial numbers peak at the top of the separate-phase oil suggesting that growth is most rapid in locations with access to both hydrocarbons and nutrients infiltrating from the surface.

  9. Microbial communities in oil-contaminated seawater

    Microsoft Academic Search

    Shigeaki Harayama; Yuki Kasai; Akihiro Hara

    2004-01-01

    Although diverse bacteria capable of degrading petroleum hydrocarbons have been isolated and characterized, the vast majority of hydrocarbon-degrading bacteria, including anaerobes, could remain undiscovered, as a large fraction of bacteria inhabiting marine environments are uncultivable. Using culture-independent rRNA approaches, changes in the structure of microbial communities have been analyzed in marine environments contaminated by a real oil spill and in

  10. Microscale Imaging: Microbial Behavior Near NAPL Surfaces

    Microsoft Academic Search

    R. Singh; M. Xu; M. S. Olson

    2006-01-01

    A comprehensive understanding of microbial transport mechanisms is needed for effective in situ bioremediation of ground water contaminants. Microscale imaging has great potential to provide insight into microbial transport and behavior in subsurface water near contaminated sites. In the present study we focus on the application of two novel microscale imaging techniques to observe microbial behavior surrounding dissolving NAPL in

  11. GEOELECTRICAL EVIDENCE OF MICROBIAL DEGRADATION OF DIESEL CONTAMINATED SEDIMENTS

    EPA Science Inventory

    The alteration of physical properties by microbial activity in petroleum contaminated sediments was investigated using geophysical techniques in laboratory column experiments. Microbial population growth was determined by the Most Probable Number technique (MPN), community dynami...

  12. Microbial cell-surface display

    Microsoft Academic Search

    Sang Yup Lee; Jong Hyun Choi; Zhaohui Xu

    2003-01-01

    Cell-surface display allows peptides and proteins to be displayed on the surface of microbial cells by fusing them with the anchoring motifs. The protein to be displayed – the passenger protein – can be fused to an anchoring motif – the carrier protein – by N-terminal fusion, C-terminal fusion or sandwich fusion. The characteristics of carrier protein, passenger protein and

  13. Cadmium Selenium Testing for Microbial Contaminants

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Cadmium selenium Quantum Dots (QDs) are metal nanoparticles that fluoresce in a variety of colors determined by their size. QDs are solid state structures made of semiconductors or metals that confine a countable, small number of electrons into a small space. The confinement of electrons is achieved by the placement of some insulating material(s) around a central, well conducted region. Coupling QDs with antibodies can be used to make spectrally multiplexed immunoassays that test for a number of microbial contaminants using a single test.

  14. Microbial contamination of used dental handpieces.

    PubMed

    Smith, Gordon; Smith, Andrew

    2014-09-01

    Microbial contamination of used, unprocessed internal components of dental handpieces (HPs) was assessed. HPs were dismantled aseptically, immersed in phosphate-buffered saline, ultrasonicated, and cultured. A median of 200 CFU per turbine (n = 40), 400 CFU per spray channel (n = 40), and 1000 CFU per item of surgical gear (n = 20) was detected. Isolates included oral streptococci, Pseudomonas spp, and Staphylococcus aureus. Recovery of S aureus confirms the need for appropriate HP cleaning and sterilization after each patient to prevent cross-infection. PMID:25179340

  15. Minimizing microbial contamination of sperm samples

    USGS Publications Warehouse

    Jenkins, Jill A.

    2011-01-01

    Taken from the Methods section: With the collection and translocation of gametes from aquatic species, a potential hazard exists for microbial transfer. Contamination of semen can occur during collection, processing, storage, and transport. Some preventative measures are described below for limiting the spread and amplification of microorganisms such as bacteria, viruses, fungi, mycoplasmas, and parasites. Generally, sanitation during collection is essential. Materials and equipment used to freeze semen should be sterile. Following good practice guidelines for handling and processing samples collected for freezing is especially important for non-domestic animals where disease-free status cannot be guaranteed and unsophisticated technology is used (Russell et al. 1977).

  16. Field Analysis of Microbial Contamination Using Three Molecular Methods in Parallel

    NASA Technical Reports Server (NTRS)

    Morris, H.; Stimpson, E.; Schenk, A.; Kish, A.; Damon, M.; Monaco, L.; Wainwright, N.; Steele, A.

    2010-01-01

    Advanced technologies with the capability of detecting microbial contamination remain an integral tool for the next stage of space agency proposed exploration missions. To maintain a clean, operational spacecraft environment with minimal potential for forward contamination, such technology is a necessity, particularly, the ability to analyze samples near the point of collection and in real-time both for conducting biological scientific experiments and for performing routine monitoring operations. Multiple molecular methods for detecting microbial contamination are available, but many are either too large or not validated for use on spacecraft. Two methods, the adenosine- triphosphate (ATP) and Limulus Amebocyte Lysate (LAL) assays have been approved by the NASA Planetary Protection Office for the assessment of microbial contamination on spacecraft surfaces. We present the first parallel field analysis of microbial contamination pre- and post-cleaning using these two methods as well as universal primer-based polymerase chain reaction (PCR).

  17. Microbial and chemical contamination during and after flooding in the Ohio River-Kentucky, 2011.

    PubMed

    Yard, Ellen E; Murphy, Matthew W; Schneeberger, Chandra; Narayanan, Jothikumar; Hoo, Elizabeth; Freiman, Alexander; Lewis, Lauren S; Hill, Vincent R

    2014-09-19

    Surface water contaminants in Kentucky during and after 2011 flooding were characterized. Surface water samples were collected during flood stage (May 2-4, 2011; n = 15) and after (July 25-26, 2011; n = 8) from four different cities along the Ohio River and were analyzed for the presence of microbial indicators, pathogens, metals, and chemical contaminants. Contaminant concentrations during and after flooding were compared using linear and logistic regression. Surface water samples collected during flooding had higher levels of E. coli, enterococci, Salmonella, Campylobacter, E. coli O157:H7, adenovirus, arsenic, copper, iron, lead, and zinc compared to surface water samples collected 3-months post-flood (P < 0.05). These results suggest that flooding increases microbial and chemical loads in surface water. These findings reinforce commonly recommended guidelines to limit exposure to flood water and to appropriately sanitize contaminated surfaces and drinking wells after contamination by flood water. PMID:24967556

  18. Materials surface contamination analysis

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Arendale, William F.

    1992-01-01

    The original research objective was to demonstrate the ability of optical fiber spectrometry to determine contamination levels on solid rocket motor cases in order to identify surface conditions which may result in poor bonds during production. The capability of using the spectral features to identify contaminants with other sensors which might only indicate a potential contamination level provides a real enhancement to current inspection systems such as Optical Stimulated Electron Emission (OSEE). The optical fiber probe can easily fit into the same scanning fixtures as the OSEE. The initial data obtained using the Guided Wave Model 260 spectrophotometer was primarily focused on determining spectra of potential contaminants such as HD2 grease, silicones, etc. However, once we began taking data and applying multivariate analysis techniques, using a program that can handle very large data sets, i.e., Unscrambler 2, it became apparent that the techniques also might provide a nice scientific tool for determining oxidation and chemisorption rates under controlled conditions. As the ultimate power of the technique became recognized, considering that the chemical system which was most frequently studied in this work is water + D6AC steel, we became very interested in trying the spectroscopic techniques to solve a broad range of problems. The complexity of the observed spectra for the D6AC + water system is due to overlaps between the water peaks, the resulting chemisorbed species, and products of reaction which also contain OH stretching bands. Unscrambling these spectral features, without knowledge of the specific species involved, has proven to be a formidable task.

  19. Microbial Biogeography of Public Restroom Surfaces

    PubMed Central

    Flores, Gilberto E.; Bates, Scott T.; Knights, Dan; Lauber, Christian L.; Stombaugh, Jesse; Knight, Rob; Fierer, Noah

    2011-01-01

    We spend the majority of our lives indoors where we are constantly exposed to bacteria residing on surfaces. However, the diversity of these surface-associated communities is largely unknown. We explored the biogeographical patterns exhibited by bacteria across ten surfaces within each of twelve public restrooms. Using high-throughput barcoded pyrosequencing of the 16 S rRNA gene, we identified 19 bacterial phyla across all surfaces. Most sequences belonged to four phyla: Actinobacteria, Bacteriodetes, Firmicutes and Proteobacteria. The communities clustered into three general categories: those found on surfaces associated with toilets, those on the restroom floor, and those found on surfaces routinely touched with hands. On toilet surfaces, gut-associated taxa were more prevalent, suggesting fecal contamination of these surfaces. Floor surfaces were the most diverse of all communities and contained several taxa commonly found in soils. Skin-associated bacteria, especially the Propionibacteriaceae, dominated surfaces routinely touched with our hands. Certain taxa were more common in female than in male restrooms as vagina-associated Lactobacillaceae were widely distributed in female restrooms, likely from urine contamination. Use of the SourceTracker algorithm confirmed many of our taxonomic observations as human skin was the primary source of bacteria on restroom surfaces. Overall, these results demonstrate that restroom surfaces host relatively diverse microbial communities dominated by human-associated bacteria with clear linkages between communities on or in different body sites and those communities found on restroom surfaces. More generally, this work is relevant to the public health field as we show that human-associated microbes are commonly found on restroom surfaces suggesting that bacterial pathogens could readily be transmitted between individuals by the touching of surfaces. Furthermore, we demonstrate that we can use high-throughput analyses of bacterial communities to determine sources of bacteria on indoor surfaces, an approach which could be used to track pathogen transmission and test the efficacy of hygiene practices. PMID:22132229

  20. Bioremediation of petroleum contaminated soil using vegetation. A microbial study

    SciTech Connect

    Lee, E.; Banks, M.K. (Kansas State Univ., Manhattan, KS (United States))

    1993-12-01

    The degradation of selected petroleum hydrocarbons in the rhizosphere of alfalfa was investigated in a greenhouse experiment. Petroleum contaminated and uncontaminated soils were spiked with 100 ppm of polynuclear aromatic and aliphatic hydrocarbons. Unspiked, uncontaminated soil was used as a control. Microbial counts for soils with and without plants for each soil treatment were performed 4, 8, 16, and 24 weeks after planting. Microbial numbers were substantially greater in soil with plants when compared to soil containing no plants, indicating that plant roots enhanced microbial populations in contaminated soil. Soil treatments had no effect on microbial numbers in the presence of plants. 12 refs., 3 figs., 1 tab.

  1. Herbicide Contamination of Freshwater Ecosystems: Impact on Microbial Communities

    E-print Network

    16 Herbicide Contamination of Freshwater Ecosystems: Impact on Microbial Communities Villeneuve A.1 contamination by a variety of mineral and organic pollutants. Most of the organic pollutants are herbicides (e). These herbicides can enter aquatic ecosystems as a result of terrestrial runoff, and to a lesser extent, of direct

  2. Rhizosphere Microbial Characterization in Petroleum-Contaminated Soil

    Microsoft Academic Search

    M. Katherine Banks; Hadessa Mallede; Karrie Rathbone

    2003-01-01

    Contamination of soil with petroleum compounds is of concern worldwide. Although there are a variety of physical and chemical technologies available to remediate petroleum waste sites, biological methods are often used due to lower cost and public acceptance. Growth and enhanced activity of microbial communities in contaminated soil is a key factor for the success of bioremediation. Establishing vegetation in

  3. Microbial contamination in poultry chillers estimated by Monte Carlo simulations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The risk of microbial contamination during poultry processing may be reduced by the operating characteristics of the chiller. The performance of air chillers and immersion chillers were compared in terms of pre-chill and post-chill contamination using Monte Carlo simulations. Three parameters were u...

  4. Surface characterization and contamination analysis

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1994-01-01

    The research activity for this first year has focussed on three distinct activities: (1) the use of an integrating sphere to improve upon the gathering of spectral data from a variety of surfaces; (2) the use of optical fiber spectrometry to determine levels of contamination from tape residues on critical bonding surfaces; and (3) an exploratory activity in the use of spectroscopic ellipsometry for the analysis of thin films of contaminants on critical surfaces has also begun.

  5. MANAGING MICROBIAL CONTAMINATION IN URBAN WATERSHEDS

    EPA Science Inventory

    This paper presents different approaches for controlling pathogen contamination in urban watersheds for contamination resulting from point and diffuses sources. Point sources of pathogens can be treated by a disinfection technology of known effectiveness, and a desired reduction ...

  6. MANAGING MICROBIAL CONTAMINATION IN URBAN WATERSHEDS

    EPA Science Inventory

    This paper presents different approaches for controlling pathogen contamination in urban watersheds for contamination resulting from point and diffuse sources. Point sources of pathogens can be treated by a disinfection technology of known effectiveness, and a desired reduction ...

  7. Surface micropattern limits bacterial contamination

    PubMed Central

    2014-01-01

    Background Bacterial surface contamination contributes to transmission of nosocomial infections. Chemical cleansers used to control surface contamination are often toxic and incorrectly implemented. Additional non-toxic strategies should be combined with regular cleanings to mitigate risks of human error and further decrease rates of nosocomial infections. The Sharklet micropattern (MP), inspired by shark skin, is an effective tool for reducing bacterial load on surfaces without toxic additives. The studies presented here were carried out to investigate the MP surfaces capability to reduce colonization of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) compared to smooth control surfaces. Methods The MP and smooth surfaces produced in acrylic film were compared for remaining bacterial contamination and colonization following inoculation. Direct sampling of surfaces was carried out after inoculation by immersion, spray, and/or touch methods. Ultimately, a combination assay was developed to assess bacterial contamination after touch transfer inoculation combined with drying (persistence) to mimic common environmental contamination scenarios in the clinic or hospital environment. The combination transfer and persistence assay was then used to test antimicrobial copper beside the MP for the ability to reduce MSSA and MRSA challenge. Results The MP reduced bacterial contamination with log reductions ranging from 87-99% (LR?=?0.90-2.18; p?surfaces. The MP was more effective than the 99.9% pure copper alloy C11000 at reducing surface contamination of S. aureus (MSSA and MRSA) through transfer and persistence of bacteria. The MP reduced MSSA by as much as 97% (LR?=?1.54; p?contamination, but reduced MRSA contamination by 80% (LR?=?0.70; p?contamination events to demonstrate the performance of a MP to limit contamination under multiple conditions. Antimicrobial copper has been implemented in hospital room studies to evaluate its impact on nosocomial infections and a decrease in HAI rate was shown. Similar implementation of the MP has potential to reduce the incidence of HAIs although future clinical studies will be necessary to validate the MP’s true impact. PMID:25232470

  8. Ecogenomics of microbial communities in bioremediation of chlorinated contaminated sites

    PubMed Central

    Maphosa, Farai; Lieten, Shakti H.; Dinkla, Inez; Stams, Alfons J.; Smidt, Hauke; Fennell, Donna E.

    2012-01-01

    Organohalide compounds such as chloroethenes, chloroethanes, and polychlorinated benzenes are among the most significant pollutants in the world. These compounds are often found in contamination plumes with other pollutants such as solvents, pesticides, and petroleum derivatives. Microbial bioremediation of contaminated sites, has become commonplace whereby key processes involved in bioremediation include anaerobic degradation and transformation of these organohalides by organohalide respiring bacteria and also via hydrolytic, oxygenic, and reductive mechanisms by aerobic bacteria. Microbial ecogenomics has enabled us to not only study the microbiology involved in these complex processes but also develop tools to better monitor and assess these sites during bioremediation. Microbial ecogenomics have capitalized on recent advances in high-throughput and -output genomics technologies in combination with microbial physiology studies to address these complex bioremediation problems at a system level. Advances in environmental metagenomics, transcriptomics, and proteomics have provided insights into key genes and their regulation in the environment. They have also given us clues into microbial community structures, dynamics, and functions at contaminated sites. These techniques have not only aided us in understanding the lifestyles of common organohalide respirers, for example Dehalococcoides, Dehalobacter, and Desulfitobacterium, but also provided insights into novel and yet uncultured microorganisms found in organohalide respiring consortia. In this paper, we look at how ecogenomic studies have aided us to understand the microbial structures and functions in response to environmental stimuli such as the presence of chlorinated pollutants. PMID:23060869

  9. Bioremediation of contaminated surface soils

    SciTech Connect

    Sims, J.L.; Sims, R.C.; Matthews, J.E.

    1989-08-01

    Biological processes, including microbial degradation, have been identified as critical mechanisms for attenuating organic contaminants during transit through the vadose zone to the groundwater. On-site soil remedial measures using biological processes can reduce or eliminate groundwater contamination, thus reducing the need for extensive groundwater monitoring and treatment requirements. On-site remedial systems that utilize the soil as the treatment system accomplish treatment by using naturally occurring microorganisms to treat the contaminants. Treatment often may be enhanced by a variety of physical/chemical methods, such as fertilization, tilling, soil pH adjustment, moisture control, etc. The development of a bioremediation program for a specific contaminated soil system includes: (1) a thorough site/soil/waste characterization; (2) treatability studies; and (3) design and implementation of the bioremediation plan. Biological remediation of soils contaminated with organic chemicals has been demonstrated to be an alternative treatment technology that can often meet the goal of achieving a permanent clean-up remedy at hazardous waste sites.

  10. PLFA analyses of microbial communities associated with PAH-contaminated riverbank sediment.

    PubMed

    Pratt, Brenda; Riesen, Roland; Johnston, Carl G

    2012-10-01

    Sediment contaminated with polycyclic aromatic hydrocarbons (PAHs) is widely distributed in aquatic ecosystems. The microbial community structure of riverbank PAH-contaminated sediments was investigated using phospholipid-derived fatty acid (PLFA) analysis. Surface and subsurface riverbank sediment was collected from a highly contaminated site and from an uncontaminated site along the Mahoning River, OH. PAH concentrations, physical sediment characteristics, and other microbial community parameters (biomass as phospholipid phosphate (PLP) and activity) were also measured. PAHs were detected in all samples but were only quantifiable in the contaminated (250 ?g/g g(-1)) subsurface sediment. Subsurface samples from both locations showed very similar PLP values and distribution of PLFAs, with 27-37 % of the microbial community structure being composed of sulfate reducing and other anaerobic bacteria. Principal components analysis indicated no correlation between PAH contamination and PLFA diversity. Although PLP and phospholipid fatty acid measurements of bacterial communities did not reflect the environmental differences among sites, the highly PAH-contaminated sediment showed the highest measured microbial activity (reduction of 1,200 nmol INT g(-1) h(-1)), likely from a population adapted to environmental pollutants, rates that are much higher than measured in many uncontaminated soil and sediment systems. These data warrant further investigation into community structure at the genetic level and indicate potential for bioremediation by indigenous microbes. PMID:22584297

  11. The impact of land use on microbial surface water pollution.

    PubMed

    Schreiber, Christiane; Rechenburg, Andrea; Rind, Esther; Kistemann, Thomas

    2015-03-01

    Our knowledge relating to water contamination from point and diffuse sources has increased in recent years and there have been many studies undertaken focusing on effluent from sewage plants or combined sewer overflows. However, there is still only a limited amount of microbial data on non-point sources leading to diffuse pollution of surface waters. In this study, the concentrations of several indicator micro-organisms and pathogens in the upper reaches of a river system were examined over a period of 16 months. In addition to bacteria, diffuse pollution caused by Giardia lamblia and Cryptosporidium spp. was analysed. A single land use type predestined to cause high concentrations of all microbial parameters could not be identified. The influence of different land use types varies between microbial species. The microbial concentration in river water cannot be explained by stable non-point effluent concentrations from different land use types. There is variation in the ranking of the potential of different land use types resulting in surface water contamination with regard to minimum, median and maximum effects. These differences between median and maximum impact indicate that small-scale events like spreading manure substantially influence the general contamination potential of a land use type and may cause increasing micro-organism concentrations in the river water by mobilisation during the next rainfall event. PMID:25456147

  12. Microbial contamination of stored hydrocarbon fuels and its control

    Microsoft Academic Search

    Christine C. Gaylarde; Fátima M. Bento; Joan Kelley

    1999-01-01

    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

  13. Bioremediation of petroleum contaminated soil using vegetation: A microbial study

    Microsoft Academic Search

    Euisang Lee; M. K. Banks

    1993-01-01

    The degradation of selected petroleum hydrocarbons in the rhizosphere of alfalfa was investigated in a greenhouse experiment. Petroleum contaminated and uncontaminated soils were spiked with 100 ppm of polynuclear aromatic and aliphatic hydrocarbons. Unspiked, uncontaminated soil was used as a control. Microbial counts for soils with and without plants for each soil treatment were performed 4, 8, 16, and 24

  14. Microbial Contamination of Chicken Wings: An Open-Ended Laboratory Project.

    ERIC Educational Resources Information Center

    Deutch, Charles E.

    2001-01-01

    Introduces the chicken wing project in which students assess the microbial contamination of chicken wings for the safety of foods. Uses the colony counting technique and direct wash fluid examination for determining the microbial contamination, and investigates methods to reduce the level of microbial contamination. (Contains 14 references.) (YDS)

  15. Response of a salt marsh microbial community to metal contamination

    NASA Astrophysics Data System (ADS)

    Mucha, Ana P.; Teixeira, Catarina; Reis, Izabela; Magalhães, Catarina; Bordalo, Adriano A.; Almeida, C. Marisa R.

    2013-09-01

    Salt marshes are important sinks for contaminants, namely metals that tend to accumulate around plant roots and could eventually be taken up in a process known as phytoremediation. On the other hand, microbial communities display important roles in the salt marsh ecosystems, such as recycling of nutrients and/or degradation of organic contaminants. Thus, plants can benefit from the microbial activity in the phytoremediation process. Nevertheless, above certain levels, metals are known to be toxic to microorganisms, fact that can eventually compromise their ecological functions. In this vein, the aim of present study was to investigate, in the laboratory, the effect of selected metals (Cd, Cu and Pb) on the microbial communities associated to the roots of two salt marsh plants. Sediments colonized by Juncus maritimus and Phragmites australis were collected in the River Lima estuary (NW Portugal), and spiked with each of the metals at three different Effects Range-Median (ERM) concentrations (1, 10×, 50×), being ERM the sediment quality guideline that indicates the concentration above which adverse biological effects may frequently occur. Spiked sediments were incubated with a nutritive saline solution, being left in the dark under constant agitation for 7 days. The results showed that, despite the initial sediments colonized by J. maritimus and P. australis displayed significant (p < 0.05) differences in terms of microbial community structure (evaluated by ARISA), they presented similar microbial abundances (estimated by DAPI). Also, in terms of microbial abundance, both sediments showed a similar response to metal addition, with a decrease in number of cells only observed for the higher addition of Cu. Nevertheless, both Cu and Pb, at intermediate metals levels promote a shift in the microbial community structure, with possibly effect on the ecological function of these microbial communities in salt marshes. These changes may affect plants phytoremediation potential and further work on this subject is in need.

  16. Molecular Profiling of Microbial Communities from Contaminated

    SciTech Connect

    Robb, Frank T.

    1999-06-01

    The major objective of the research is to provide appropriate sequences and to assemble a high density DNA array of oligonucleotides that can be used for rapid profiling of microbial populations, from polluted areas and from areas of other interest. The sequences to be assigned to the DNA array are chosen from cloned genomic DNA from groundwater at DOE sites containing organic solvents. The sites, Hanford Nuclear Plant and Lawrence Livermore Site 300 (LLNL), have well characterized pollutant histories, which have been provided by our collaborators.

  17. [Monitoring of microbial contamination of stick wound in swine carcasses].

    PubMed

    Rheault, N; Quessy, S

    1999-04-01

    This study was done to evaluate the microbial contamination by Salmonella spp., Escherichia coli, fecal coliforms, and total aerobic count of the stick wound of swine carcasses. The effectiveness of trimming the stick wound in the 2 Québec slaughterhouses visited was evaluated. A bacteriological analysis was done on 276 stick wounds. Results indicated that, before trimming, 0.9% stick wounds were contaminated by Salmonella spp. Contamination by coliforms was observed in 40.6% of samples, and 27.7% were positive for E. coli. After trimming the stick wounds, 1.1% were contaminated by Salmonella spp., 34.1% were contaminated by coliforms, and 26.2% were positive for E. coli. The results showed that trimming contributes to reducing significantly the bacterial total count at the site and that the bacterial load at this site was less important than that found on the brisket. PMID:10200884

  18. Specificity of marine microbial surface interactions.

    PubMed Central

    Imam, S H; Bard, R F; Tosteson, T R

    1984-01-01

    The macromolecular surface components involved in intraspecific cell surface interactions of the green microalga Chlorella vulgaris and closely associated bacteria were investigated. The specific surface attachment between this alga and its associated bacteria is mediated by lectin-like macromolecules associated with the surfaces of these cells. The binding activity of these surface polymers was inhibited by specific simple sugars; this suggests the involvement of specific receptor-ligand binding sites on the interactive surfaces. Epifluorescent microscopic evaluation of bacteria-alga interactions in the presence and absence of the macromolecules that mediate these interactions showed that the glycoproteins active in these processes were specific to the microbial sources from which they were obtained. The demonstration and definition of the specificity of these interactions in mixed microbial populations may play an important role in our understanding of the dynamics of marine microbial populations in the sea. PMID:6508293

  19. Microbially driven fenton reaction for degradation of the widespread environmental contaminant 1,4-dioxane.

    PubMed

    Sekar, Ramanan; DiChristina, Thomas J

    2014-11-01

    The carcinogenic cyclic ether compound 1,4-dioxane is employed as a stabilizer of chlorinated industrial solvents and is a widespread environmental contaminant in surface water and groundwater. In the present study, a microbially driven Fenton reaction was designed to autocatalytically generate hydroxyl (HO•) radicals that degrade 1,4-dioxane. In comparison to conventional (purely abiotic) Fenton reactions, the microbially driven Fenton reaction operated at circumneutral pH and did not the require addition of exogenous H2O2 or UV irradiation to regenerate Fe(II) as Fenton reagents. The 1,4-dioxane degradation process was driven by pure cultures of the Fe(III)-reducing facultative anaerobe Shewanella oneidensis manipulated under controlled laboratory conditions. S. oneidensis batch cultures were provided with lactate, Fe(III), and 1,4-dioxane and were exposed to alternating aerobic and anaerobic conditions. The microbially driven Fenton reaction completely degraded 1,4-dioxane (10 mM initial concentration) in 53 h with an optimal aerobic-anaerobic cycling period of 3 h. Acetate and oxalate were detected as transient intermediates during the microbially driven Fenton degradation of 1,4-dioxane, an indication that conventional and microbially driven Fenton degradation processes follow similar reaction pathways. The microbially driven Fenton reaction provides the foundation for development of alternative in situ remediation technologies to degrade environmental contaminants susceptible to attack by HO• radicals generated by the Fenton reaction. PMID:25313646

  20. Sequester of metals and mineralization of organic contaminants with microbial mats

    SciTech Connect

    Bender, J.; Phillips, P.; Gould, J.P. [M.A.T.S., Inc., Atlanta, GA (United States)

    1995-12-31

    Several recalcitrant organic contaminants are completely mineralized to simple products by microbial mats. Contaminants include chlordane, PCB, TNT, petroleum distillates, BM compounds and TCE in a mixed contaminant solution containing Zn. Degradation rates are relatively rapid under both dark and light conditions. In addition to complete degradation of organic materials, mats have been used to reduce selenate to elemental selenium, remove Pb, Cd, Cu, Zn, Co, Cr, Fe and Mn from water and sequester uranium (U{sup 238}) at a rate of 3.19 mg/m{sup 2}/h. Results of three pilot projects, including field pond treatment of mine drainage and bioreactor treatment of BTEX compounds will be reported. Microbial mats are natural heterotrophic and autotrophic communities dominated by cyanobacteria (blue-green algae). They are self-organized laminated structures annealed fightly together by slimy secretions from various microbial components. The surface slime of the mats effectively immobilizes the ecosystem to a variety of substrates, thereby stabilizing the most efficient internal microbial structure. Cyanobacteria mats are generated for bioremediation applications by enriching a water surface with ensiled grass clippings together with mat inocula developed in the laboratory.

  1. Control of microbial contamination with commercially available cleaning solutions.

    PubMed

    Assery, M; Sugrue, P C; Graser, G N; Eisenberg, A D

    1992-02-01

    The elimination of cross-contamination from operatory to laboratory is required for effective infection control. This study determined whether microbial cross-contamination occurs during cleaning of dental prostheses with an ultrasonicator and examined ways to reduce or eliminate the contamination that might occur. The antimicrobial activities of a temporary cement remover and tartar and stain remover were compared with deionized water and a known strong antimicrobial agent. All solutions were assessed without and with ultrasonication. The microbicidal strains were cultured in brain-heart infusion broth, with and without acrylic resin slabs, and the organisms were killed either without or with sonication and without or with acrylic resin slabs. Further testing with natural plaque-contaminated denture materials is warranted. PMID:1538340

  2. Removal of paper microbial contamination by atmospheric pressure DBD discharge

    NASA Astrophysics Data System (ADS)

    Vrajova, J.; Chalupova, L.; Novotny, O.; Cech, J.; Krcma, F.; Stahel, P.

    2009-08-01

    In this paper the removal of the microbial contamination from paper material using the plasma treatment at atmospheric pressure is investigated. The Aspergillus niger has been chosen as a bio-indicator enabling to evaluate the effect of plasma assisted microbial inactivation. Dielectric barrier discharge (DBD) operated at atmospheric pressure was used for the paper sterilization. The working gas (nitrogen, argon and helium), plasma exposition time and the plasma power density were varied in order to see the effect of the plasma treatment on the fungi removal. After the treatment, the microbial abatement was evaluated by the standard plate count method. This proved a positive effect of the DBD plasma treatment on fungi removal. Morphological and colorimetric changes of paper substrate after plasma treatment were also investigated.

  3. Optical measurements on contaminated surfaces

    NASA Technical Reports Server (NTRS)

    Bonham, T. E.; Schmitt, R. J.; Linford, R. M. F.

    1975-01-01

    A bidirectional reflectometer system was developed for in situ measurements of the changes in spectral reflectance of surfaces contaminated with films of organic materials. The system permits experiments with films of controlled thickness in an environment that simulates the thermal, radiation, and vacuum conditions of space. The mechanical and optical construction of the reflectometer are discussed in detail, and actual data curves are used to illustrate its operation and performance.

  4. Control of microbial contamination in unpreserved eyedrops.

    PubMed Central

    Oldham, G. B.; Andrews, V.

    1996-01-01

    AIMS/BACKGROUND: Preservatives are added to multidose eyedrop containers to ensure that the eyedrops do not become heavily contaminated during patient use. This enables eyedrops to be used for up to 1 month after opening. However, patients are frequently required to use unpreserved eyedrops as their eyes are unable to tolerate these preservatives. Some commercial unpreserved unit dose eyedrops are available, but the range is limited, and they cannot be used in all cases. Twenty one different unpreserved eyedrop formulations in multidose bottles were tested to establish their inherent efficacy in antimicrobial preservation, and to help determine a suitable in use storage life. METHODS: The eyedrops were inoculated with a known quantity of four different micro-organisms according to the method of the European Pharmacopoeia 'Test for the efficacy of antimicrobial preservation'. After set periods of time, samples were taken to determine the number of viable organisms remaining. RESULTS: Antibiotics and alkaloids were generally shown to have higher kill rates than other eyedrops such as artificial tears and steroids. CONCLUSIONS: In general, once opened by individual patients in a domiciliary situation, a 7 day in use storage life is confirmed for eyedrops containing alkaloids or antibiotics, if they are stored in the refrigerator after opening. PMID:8795368

  5. EVIDENCE FOR MICROBIAL ENHANCED ELECTRICAL CONDUCTIVITY IN HYDROCARBON-CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Electrical conductivity of sediments during microbial mineralization of diesel was investigated in a mesoscale column experiment consisting of biotic contaminated and uncontaminated columns. Microbial population numbers increased with a clear pattern of depth zonation within the ...

  6. Enhanced detection of groundwater contamination from a leaking waste disposal site by microbial community profiles

    E-print Network

    Vermont, University of

    Enhanced detection of groundwater contamination from a leaking waste disposal site by microbial of groundwater contamination. We sampled profiles of the microbial community from monitoring wells surrounding, P. O'Grady, and L. Stevens (2010), Enhanced detection of groundwater contamination from a leaking

  7. On microbial contaminants, micropseudofossils, and the oldest records of life

    USGS Publications Warehouse

    Cloud, P.; Morrison, K.

    1979-01-01

    Microbial contaminants may be introduced on outcrop as well as en route to or in the laboratory. Micropseudofossils may be natural or man-made. It is possible to recognize such misleading objects and important that they are not allowed to dilute the growing record of authentic pre-Phanerozoic life. Filamentous microbial contaminants from minute cracks in samples of ancient carbonate rocks from Brazil (perhaps 1 Ga old) and South Africa (???2.3 Ga old) are similar to occurrences previously described as fossils. Published records of supposedly Archean microbial life also include microcontaminants and laboratory artifacts. Although microstructures from sedimentary rocks of the Swaziland system could be fossils, they are not demonstrably so. The oldest structurally preserved fossils yet known seem to be the filaments described by Lois Nagy from stromatolitic limestone in the ???2.3 Ga old Malmani Dolomite of South Africa. It will be difficult to establish unequivocal older records in the absence of definitive ultrastructural or micro-chemical evidence. ?? 1979.

  8. Microbial contamination of drinking water in Pakistan--a review.

    PubMed

    Nabeela, Farhat; Azizullah, Azizullah; Bibi, Roqaia; Uzma, Syeda; Murad, Waheed; Shakir, Shakirullah Khan; Ullah, Waheed; Qasim, Muhammad; Häder, Donat-Peter

    2014-12-01

    Water pollution with pathogenic microorganisms is one of the serious threats to human health, particularly in developing countries. The main objective of this article is to highlight microbial contamination of drinking water, the major factors responsible for microbial contamination, and the resulting health problems in Pakistan. Furthermore, this study will be helpful for researchers and administrative agencies to initiate relevant studies and develop new policies to protect further deterioration of water supply with pathogenic microbes and ensure clean and safe drinking water to the public in Pakistan. In Pakistan, water at the source, in the distribution network, and at the consumer tap is heavily polluted with coliforms and fecal coliforms all over the country. An overview of more than 7,000 water samples reviewed here reveals that an average of over 71 and 58 % samples in the country was contaminated with total coliforms and fecal coliforms, respectively. Drinking water contamination accounts for 20 to 40 % of all diseases in the country, which causes national income losses of Rs 25-58 billion annually (US$0.25-0.58 billion, approximately 0.6-1.44 % of the country's GDP). Improper disposal of industrial and municipal wastes is the most important factor responsible for water pollution in the country followed by cross-contamination due to old and leaking pipes and lack of water filtration and disinfection facilities. There is an urgent need for emergency steps to stop further deterioration of water quality and improve the existing water quality so as to protect the public from widespread waterborne diseases. PMID:25056753

  9. Biofilms: Microbial Life on Surfaces

    Microsoft Academic Search

    Rodney M. Donlan

    2002-01-01

    Microorganisms attach to surfaces and develop biofilms. Biofilm-associated cells can be differentiated from their suspended counterparts by generation of an extracellular polymeric substance (EPS) matrix, reduced growth rates, and the up- and down-regulation of specific genes. Attachment is a complex pro- cess regulated by diverse characteristics of the growth medium, substratum, and cell surface. An estab- lished biofilm structure comprises

  10. Functional gene diversity of soil microbial communities from five oil-contaminated fields in China

    PubMed Central

    Liang, Yuting; Van Nostrand, Joy D; Deng, Ye; He, Zhili; Wu, Liyou; Zhang, Xu; Li, Guanghe; Zhou, Jizhong

    2011-01-01

    To compare microbial functional diversity in different oil-contaminated fields and to know the effects of oil contaminant and environmental factors, soil samples were taken from typical oil-contaminated fields located in five geographic regions of China. GeoChip, a high-throughput functional gene array, was used to evaluate the microbial functional genes involved in contaminant degradation and in other major biogeochemical/metabolic processes. Our results indicated that the overall microbial community structures were distinct in each oil-contaminated field, and samples were clustered by geographic locations. The organic contaminant degradation genes were most abundant in all samples and presented a similar pattern under oil contaminant stress among the five fields. In addition, alkane and aromatic hydrocarbon degradation genes such as monooxygenase and dioxygenase were detected in high abundance in the oil-contaminated fields. Canonical correspondence analysis indicated that the microbial functional patterns were highly correlated to the local environmental variables, such as oil contaminant concentration, nitrogen and phosphorus contents, salt and pH. Finally, a total of 59% of microbial community variation from GeoChip data can be explained by oil contamination, geographic location and soil geochemical parameters. This study provided insights into the in situ microbial functional structures in oil-contaminated fields and discerned the linkages between microbial communities and environmental variables, which is important to the application of bioremediation in oil-contaminated sites. PMID:20861922

  11. Studies on possible propagation of microbial contamination in planetary clouds

    NASA Technical Reports Server (NTRS)

    Dimmick, R. L.; Chatigny, M. A.

    1973-01-01

    Current U.S. planetary quarantine standards based on international agreements require consideration of the probability of contamination (Pc) of the outer planets, Venus, Jupiter, Saturn, etc. One of the key parameters in estimation of the Pc of these planets is the probability of growth (Pg) of terrestrial microorganisms on or near these planets. For example, Jupiter and Saturn appear to have an atmosphere in which some microbial species could metabolize and propagate. This study includes investigation of the likelihood of metabolism and propagation of microbes suspended in dynamic atmospheres. It is directed toward providing experimental information needed to aid in rational estimation of Pg for these outer plants.

  12. Detector for Particle Surface Contamination

    NASA Technical Reports Server (NTRS)

    Mogan, Paul A. (Inventor); Schwindt, Christian J. (Inventor); Mattson, Carl B. (Inventor)

    1999-01-01

    A system and method for detecting and quantizing particle fallout contamination particles which are collected on a transparent disk or other surface employs an optical detector, such as a CCD camera, to obtain images of the disk and a computer for analyzing the images. From the images, the computer detects, counts and sizes particles collected on the disk The computer also determines, through comparison to previously analyzed images, the particle fallout rate, and generates an alarm or other indication if the rate exceeds a maximum allowable value. The detector and disk are disposed in a housing having an aperture formed therein for defining the area on the surface of the disk which is exposed to the particle fallout. A light source is provided for evenly illuminating the disk. A first drive motor slowly rotates the disk to increase the amount of its surface area which is exposed through the aperture to the particle fallout. A second motor is also provided for incrementally scanning the disk in a radial direction back and forth over the camera so that the camera eventually obtains images of the entire surface of the disk which is exposed to the particle fallout.

  13. [Microbial contamination of cuffs lab coats during health care].

    PubMed

    Margarido, Carla Auxiliadora; Villas Boas, Tamires Monteiro; Mota, Valeria Siqueira; da Silva, Cristiane Karina Malvezzi; Poveda, Vanessa de Brito

    2014-01-01

    The study aimed to evaluate the bacterial contamination in lab coats worn by nursing students, before and after being worn in health care practices. A quantitative and descriptive study was carried out, in which the students' coats were collected, washed and ironed in a standardized way and wore for four hours in assistance activities. Subsequently, samples from the cuffs were collected with sterile cotton swabs in order to be incubated in order to analyze microbial growth through morphological analysis by Gram's Method and antibiogram. There was bacterial growth of Staphylococcus aureus and Staphylococcus epidermidis in 50% of the collected samples and Staphylococcus aureus, found in patients with wounds in outpatient care, showed resistance to antibiotics such as Vancomycin, Chloramphenicol and Sulfonamides. The data demonstrated that the lab coats wore during assistance activities, even in short periods, are effectively contaminated by strains resistant to antibiotics and can potentially cause infection related to health care. PMID:24676079

  14. Microbial community structures in anoxic freshwater lake sediment along a metal contamination gradient

    PubMed Central

    Gough, Heidi L; Stahl, David A

    2011-01-01

    Contamination, such as by heavy metals, has frequently been implicated in altering microbial community structure. However, this association has not been extensively studied for anaerobic communities, or in freshwater lake sediments. We investigated microbial community structure in the metal-contaminated anoxic sediments of a eutrophic lake that were impacted over the course of 80 years by nearby zinc-smelting activities. Microbial community structure was inferred for bacterial, archaeal and eukaryotic populations by evaluating terminal restriction fragment length polymorphism (TRFLP) patterns in near-surface sediments collected in triplicate from five areas of the lake that had differing levels of metal contamination. The majority of the fragments in the bacterial and eukaryotic profiles showed no evidence of variation in association with metal contamination levels, and diversity revealed by these profiles remained consistent even as metal concentrations varied from 3000 to 27?000?mg?kg?1 total Zn, 0.125 to 11.2?? pore water Zn and 0.023 to 5.40?? pore water As. Although most archaeal fragments also showed no evidence of variation, the prevalence of a fragment associated with mesophilic Crenarchaeota showed significant positive correlation with total Zn concentrations. This Crenarchaeota fragment dominated the archaeal TRFLP profiles, representing between 35% and 79% of the total measured peak areas. Lake DePue 16S rRNA gene sequences corresponding to this TRFLP fragment clustered with anaerobic and soil mesophilic Crenarchaeota sequences. Although Crenarchaeota have been associated with metal-contaminated groundwater and soils, this is a first report (to our knowledge) documenting potential increased prevalence of Crenarchaeota associated with elevated levels of metal contamination. PMID:20811473

  15. Rapid diagnosis of bacterial contamination of blood: comparison of three automated microbial detection systems.

    PubMed

    D'Antonio, D; Iacone, A; Betti, S; Violante, B; Parruti, G; Piergallini, A; Di Gianfilippo, R; Catinella, V; Striani, P; Dell'Isola, M

    1993-12-01

    Rapid methods of determining microbial contamination are needed in suspecting contaminated banked blood or other blood products. In this study, we experimented contaminated blood units with 122 strains of bacteria and fungi. After innoculation, a comparison between ESP Blood Culture System (Difco Laboratories Inc., Detroit MI), BacT/Alert (Organon Teknica, Durham, NC) and Bactec 9240 System was made for their efficiency in the detection of microbial contamination. Experimental data showed a diagnostic relevance of these automated systems with no significant differences in time detection of microbial contamination between the three methods under comparison. PMID:8013996

  16. Methodology for Modeling the Microbial Contamination of Air Filters

    PubMed Central

    Joe, Yun Haeng; Yoon, Ki Young; Hwang, Jungho

    2014-01-01

    In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter. PMID:24523908

  17. Risk factors for microbial contamination in fruits and vegetables at the preharvest level: a systematic review.

    PubMed

    Park, Sangshin; Szonyi, Barbara; Gautam, Raju; Nightingale, Kendra; Anciso, Juan; Ivanek, Renata

    2012-11-01

    The objective of this study was to perform a systematic review of risk factors for contamination of fruits and vegetables with Listeria monocytogenes, Salmonella, and Escherichia coli O157:H7 at the preharvest level. Relevant studies were identified by searching six electronic databases: MEDLINE, EMBASE, CAB Abstracts, AGRIS, AGRICOLA, and FSTA, using the following thesaurus terms: L. monocytogenes, Salmonella, E. coli O157 AND fruit, vegetable. All search terms were exploded to find all related subheadings. To be eligible, studies had to be prospective controlled trials or observational studies at the preharvest level and had to show clear and sufficient information on the process in which the produce was contaminated. Of the 3,463 citations identified, 68 studies fulfilled the eligibility criteria. Most of these studies were on leafy greens and tomatoes. Six studies assessed produce contamination with respect to animal host-related risk factors, and 20 studies assessed contamination with respect to pathogen characteristics. Sixty-two studies assessed the association between produce contamination and factors related to produce, water, and soil, as well as local ecological conditions of the production location. While evaluations of many risk factors for preharvest-level produce contamination have been reported, the quality assessment of the reviewed studies confirmed the existence of solid evidence for only some of them, including growing produce on clay-type soil, the application of contaminated or non-pH-stabilized manure, and the use of spray irrigation with contaminated water, with a particular risk of contamination on the lower leaf surface. In conclusion, synthesis of the reviewed studies suggests that reducing microbial contamination of irrigation water and soil are the most effective targets for the prevention and control of produce contamination. Furthermore, this review provides an inventory of the evaluated risk factors, including those requiring more research. PMID:23127717

  18. Microbial contamination of mobile phones in a health care setting in Alexandria, Egypt

    PubMed Central

    Selim, Heba Sayed; Abaza, Amani Farouk

    2015-01-01

    Aim: This study aimed at investigating the microbial contamination of mobile phones in a hospital setting. Methods: Swab samples were collected from 40 mobile phones of patients and health care workers at the Alexandria University Students’ Hospital. They were tested for their bacterial contamination at the microbiology laboratory of the High Institute of Public Health. Quantification of bacteria was performed using both surface spread and pour plate methods. Isolated bacterial agents were identified using standard microbiological methods. Methicillin-resistant Staphylococcus aureus was identified by disk diffusion method described by Bauer and Kirby. Isolated Gram-negative bacilli were tested for being extended spectrum beta lactamase producers using the double disk diffusion method according to the Clinical and Laboratory Standards Institute recommendations. Results: All of the tested mobile phones (100%) were contaminated with either single or mixed bacterial agents. The most prevalent bacterial contaminants were methicillin-resistant S. aureus and coagulase-negative staphylococci representing 53% and 50%, respectively. The mean bacterial count was 357 CFU/ml, while the median was 13 CFU/ml using the pour plate method. The corresponding figures were 2,192 and 1,720 organisms/phone using the surface spread method. Conclusions: Mobile phones usage in hospital settings poses a risk of transmission of a variety of bacterial agents including multidrug-resistant pathogens as methicillin-resistant S. aureus. The surface spread method is an easy and useful tool for detection and estimation of bacterial contamination of mobile phones. PMID:25699226

  19. A PILOT STUDY TO COMPARE MICROBIAL AND CHEMICAL INDICATORS OF HUMAN FECAL CONTAMINATION IN WATER

    EPA Science Inventory

    Limitations exist in applying traditional microbial methods for the detection of human fecal contamination of water. A pilot study was undertaken to compare the microbial and chemical indicators of human fecal contamination of water. Sixty-four water samples were collected in O...

  20. Geoelectrical Evidence of Microbial Degradation of Diesel Contaminated Sediments

    NASA Astrophysics Data System (ADS)

    Werkema, D. D.; Atekwana, E. A.; Rossbach, S.; Sauck, W. A.

    2003-12-01

    The alteration of physical properties by microbial activity in petroleum contaminated sediments was investigated using geophysical techniques in laboratory column experiments. Microbial population growth was determined by the Most Probable Number technique (MPN), community dynamics were determined by the rDNA intergenic spacer analysis (RISA), microbial mineralization of diesel fuel was assessed using dissolved inorganic carbon (DIC), enhanced mineral dissolution was determined by dissolved calcium, and the vertical geoelectrical profile was measured using DC resistivity (converted to conductivity). The columns simulated a saturation profile and contained sanitized, uniform sand with the following experimental treatments: diesel + microbes, diesel, microbes, and no treatment. After 16 months, two important conclusions were drawn. First, the relative increase in magnitude of the parameters measured was highest in the diesel + microbe column (showing at least 110% increase), lower in the diesel column and lowest (actually showing a decrease) in the column with no treatment. Further, the diesel + microbe column showed the greatest increase in oil degrading microbial populations (135%) compared to the column with no treatment, which showed no changes. Secondly, the depth at which the conductivity reached the maximum occurred within and slightly above the diesel layer (which represents a depth that was originally water wet). It was further observed that the relative change in bulk conductivity below the saturated zone is of a lower magnitude than above (<10%). These results suggest the diesel layer, and the zone slightly above, were the most biologically active. Additionally, the diesel + microbe column showed RISA fragments attributed to microbial succession typically observed in organic contaminant plumes. A simple Archie's Law analysis was used to estimate the pore water conductivities necessary to reproduce the bulk conductivity measured. This analysis shows that relative to the column with only microbes (selected as the control to be most representative of field conditions), the diesel column revealed a 2.3 fold increase and the diesel + microbe column showed a 3 fold increase in pore water conductivity. This increase was located within the diesel layer above the water saturated zone. Within the saturated zone, the no treatment column showed a 0.81 fold increase, the diesel column a 1.28, and the diesel + microbe column 1.45. We conclude from this study that microbial activity and the resultant biogeochemical changes played an important role in modifying the geoelectrical properties of aquifers and sediments rich in organic carbon and mineralized by bacteria by increasing the bulk conductivity. This conductive zone occurred within and immediately above the free-phase petroleum layer. In natural environments with high concentrations of organic compounds available as electron donors, geophysical techniques may potentially be used as indicators of microbial activity. Notice: This is an abstract of a proposed presentation and does not necessarily reflect the United States Environmental Protection Agency (EPA) policy. The actual presentation has not been peer reviewed by EPA. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

  1. Microscale Imaging: Microbial Behavior Near NAPL Surfaces

    NASA Astrophysics Data System (ADS)

    Singh, R.; Xu, M.; Olson, M. S.

    2006-12-01

    A comprehensive understanding of microbial transport mechanisms is needed for effective in situ bioremediation of ground water contaminants. Microscale imaging has great potential to provide insight into microbial transport and behavior in subsurface water near contaminated sites. In the present study we focus on the application of two novel microscale imaging techniques to observe microbial behavior surrounding dissolving NAPL in porous media: we use micro-CT to quantify bioenhancement of NAPL dissolution and we use two-color molecular probes to observe NAPL toxicity at the NAPL/water interface using fluorescence microscopy. Microcomputed Tomography (micro-CT) is a non-invasive imaging technique that allows visualization and quantification of the internal features of objects and porous media. The dissolution rate of TCE droplets dispersed in 1-mm-diameter glass beads was compared for water-saturated beads and beads containing an aqueous suspension of Pseudomonas putida F1. Changing volumes of NAPL ganglia were measured over time using micro-CT, and used to compute the mass transfer rate coefficient of TCE, with and without microbial degradation. Comparison of the mass transfer rate coefficients of TCE will be discussed. In addition, a novel method was developed to image both chemotaxis and the toxic effect of a dissolving NAPL droplet on the surrounding population of P. putida F1. Chemotaxis refers to the movement of bacteria under the influence of chemical gradient (either away or toward), which helps them to find an optimal concentration for their growth and survival. Agarose plug assays, in combination with a two-color fluorescence assay of bacterial viability, were used for investigation. Bacteria were stained with a mixture of SYTO 9 nucleic acid stain and propidium iodide. The stained bacterial solution was flooded into a chamber formed around an agarose plug containing TCE. Bacterial chemotactic response to TCE dissolution was measured by imaging the characteristic colored chemotactic band of bacterial accumulation a short distance away from the plug. Spatial distribution of live (green) and dead or damaged (red) cells around the plug changes with time as TCE diffuses into the surrounding medium and hence can be used as a toxicity indicator for P. putida F1.

  2. Surface evaluation of UV-degraded contamination

    NASA Technical Reports Server (NTRS)

    Connatser, Robert; Hadaway, James B.

    1992-01-01

    Three different areas of work were accomplished under this contract: (1) contamination testing and evaluation; (2) UV irradiation testing; and (3) surface evaluation testing. Contamination testing was generally performed in the In-Situ Contamination Effects Facility at Marshall Space Flight Center (MSFC). UV irradiation testing was also performed primarily at MSFC, utilizing facilities there. Finally, the surface evaluation was done at facilities at UAH Center for Applied Optics.

  3. Microbial reduction of intragrain U(VI) in contaminated sediment.

    PubMed

    Liu, Chongxuan; Zachara, John M; Zhong, Lirong; Heald, Steve M; Wang, Zheming; Jeon, Byong-Hun; Fredrickson, James K

    2009-07-01

    The accessibility of precipitated, intragrain U(VI) in a contaminated sediment to microbial reduction was investigated to ascertain geochemical and microscopic transport phenomena controlling U(VI) bioavailability. The sediment was collected from the U.S. Department of Energy Hanford site, and contained uranyl precipitates within the mm-sized granitic lithic fragments in the sediment. Bioreduction was investigated in a culture of a dissimilatory metal-reducing bacterium, Shewanellea oneidensis strain MR-1. Measurements of uranium concentration, speciation, and valence in aqueous and solid phases indicated that microbial reduction of intragrain U(VI) proceeded by two mechanisms: (1) sequentially coupled dissolution of intragrain uranyl precipitates, diffusion of dissolved U(VI) from intragrain regions, and microbial reduction of dissolved U(VI); and (2) U(VI) reduction in the intragrain regions by soluble, diffusible biogenic reductants. The bioreduction rate in the first pathway was over 3 orders of magnitude slowerthan that in comparable aqueous solutions containing aqueous U(VI) only. The slower bioreduction rate was attributed to (1) the release of calcium from the desorption/dissolution of calcium-containing minerals in the sediment, which subsequently altered U(VI) aqueous speciation and slowed U(VI) bioreducton and (2) alternative electron transfer pathways that reduced U(VI) in the intragrain regions and changed its dissolution and solubility behavior. The results implied that the overall rate of bioreduction of intragrain U(VI) will be influenced by the reactive mass transfer of U(VI) and biogenic reductants within intragrain regions, and geochemical reactions controlling major ion concentrations. PMID:19673287

  4. Mitigation of radiation induced surface contamination

    SciTech Connect

    Klebanoff, Leonard E. (Dublin, CA); Stulen, Richard H. (Livermore, CA)

    2003-01-01

    A process for mitigating or eliminating contamination and/or degradation of surfaces having common, adventitious atmospheric contaminants adsorbed thereon and exposed to radiation. A gas or a mixture of gases is introduced into the environment of a surface(s) to be protected. The choice of the gaseous species to be introduced (typically a hydrocarbon gas, water vapor, or oxygen or mixtures thereof) is dependent upon the contaminant as well as the ability of the gaseous species to bind to the surface to be protected. When the surface and associated bound species are exposed to radiation reactive species are formed that react with surface contaminants such as carbon or oxide films to form volatile products (e.g., CO, CO.sub.2) which desorb from the surface.

  5. Surface contamination on LDEF exposed materials

    NASA Technical Reports Server (NTRS)

    Hemminger, Carol S.

    1992-01-01

    X-ray photoelectron spectroscopy (XPS) has been used to study the surface composition and chemistry of Long Duration Exposure Facility (LDEF) exposed materials including silvered Teflon (Ag/FEP), Kapton, S13GLO paint, quartz crystal monitors (QCM's), carbon fiber/organic matrix composites, and carbon fiber/Al Alloy composites. In each set of samples, silicones were the major contributors to the molecular film accumulated on the LDEF exposed surfaces. All surfaces analyzed have been contaminated with Si, O, and C; most have low levels (less than 1 atom percent) of N, S, and F. Occasionally observed contaminants included Cl, Na, K, P, and various metals. Orange/brown discoloration observed near vent slots in some Ag/FEP blankets were higher in carbon, sulfur, and nitrogen relative to other contamination types. The source of contamination has not been identified, but amine/amide functionalities were detected. It is probable that this same source of contamination account for the low levels of sulfur and nitrogen observed on most LDEF exposed surfaces. XPS, which probes 50 to 100 A in depth, detected the major sample components underneath the contaminant film in every analysis. This probably indicates that the contaminant overlayer is patchy, with significant areas covered by less that 100 A of molecular film. Energy dispersive x-ray spectroscopy (EDS) of LDEF exposed surfaces during secondary electron microscopy (SEM) of the samples confirmed contamination of the surfaces with Si and O. In general, particulates were not observed to develop from the contaminant overlayer on the exposed LDEF material surfaces. However, many SiO2 submicron particles were seen on a masked edge of an Ag/FEP blanket. In some cases such as the carbon fiber/organic matrix composites, interpretation of the contamination data was hindered by the lack of good laboratory controls. Examination of laboratory controls for the carbon fiber/Al alloy composites showed that preflight contamination was the most significant factor for all the contaminants generally detected at less than 1 atom percent, or detected only occasionally (i.e., all but Si, O, and C). Flight control surfaces, including sample backsides not exposed to space radiation or atomic oxygen flux, have accumulated some contamination on flight (compared to laboratory controls), but experimentally, the LDEF exposed surface contamination levels are generally higher for the contaminants Si and O. For most materials analyzed, Si contamination levels were higher on the leading edge surfaces than on the trailing edge surfaces. This was true even for the composite samples where considerable atomic oxygen erosion of the leading edge surfaces was observed by SEM. It is probable that the return flux associated with atmospheric backscatter resulted in enhanced deposition of silicones and other contaminants on the leading edge flight surfaces relative to the trailing edge. Although the Si concentration data suggested greater on-flight deposition of contaminants on the leading edge surfaces, the XPS analyses did not conclusively show different relative total thicknesses of flight deposited contamination for leading and trailing edge surfaces. It is possible that atomic oxygen reactions on the leading edge resulted in greater volatilization of the carbon component of the deposited silicones, effectively 'thinning' the leading edge deposited overlayer. Unlike other materials, exposed polymers such as Kapton and FEP-type Teflon had very low contamination on the leading edge surfaces. SEM evidence showed that undercutting of the contaminant overlayer and damaged polymer layers occurred during atomic oxygen erosion, which would enhance loss of material from the exposed surface.

  6. Enzyme-enabled responsive surfaces for anti-contamination materials.

    PubMed

    Wu, Songtao; Buthe, Andreas; Jia, Hongfei; Zhang, Minjuan; Ishii, Masahiko; Wang, Ping

    2013-06-01

    Many real-life stains have origins from biological matters including proteins, lipids, and carbohydrates that act as gluing agents binding along with other particulates or microbes to exposed surfaces of automobiles, furniture, and fabrics. Mimicking naturally occurring self-defensive processes, we demonstrate in this work that a solid surface carrying partially exposed enzyme granules protected the surface in situ from contamination by biological stains and fingerprints. Attributed to the activities of enzymes which can be made compatible with a wide range of materials, such anti-contamination and self-cleaning functionalities are highly selective and efficient toward sticky chemicals. This observation promises a new mechanism in developing smart materials with desired anti-microbial, self-reporting, self-cleaning, or self-healing functions. PMID:23335427

  7. The effects of perennial ryegrass and alfalfa on microbial abundance and diversity in petroleum contaminated soil

    Microsoft Academic Search

    Jennifer L. Kirk; John N. Klironomos; Hung Lee; Jack T. Trevors

    2005-01-01

    Enhanced rhizosphere degradation uses plants to stimulate the rhizosphere microbial community to degrade organic contaminants. We measured changes in microbial communities caused by the addition of two species of plants in a soil contaminated with 31,000 ppm of total petroleum hydrocarbons. Perennial ryegrass and\\/or alfalfa increased the number of rhizosphere bacteria in the hydrocarbon-contaminated soil. These plants also increased the

  8. Microbial monitoring of surface water in South Africa: an overview.

    PubMed

    Luyt, Catherine D; Tandlich, Roman; Muller, Wilhelmine J; Wilhelmi, Brendan S

    2012-08-01

    Infrastructural problems force South African households to supplement their drinking water consumption from water resources of inadequate microbial quality. Microbial water quality monitoring is currently based on the Colilert®18 system which leads to rapidly available results. Using Escherichia coli as the indicator microorganism limits the influence of environmental sources on the reported results. The current system allows for understanding of long-term trends of microbial surface water quality and the related public health risks. However, rates of false positive for the Colilert®18-derived concentrations have been reported to range from 7.4% to 36.4%. At the same time, rates of false negative results vary from 3.5% to 12.5%; and the Colilert medium has been reported to provide for cultivation of only 56.8% of relevant strains. Identification of unknown sources of faecal contamination is not currently feasible. Based on literature review, calibration of the antibiotic-resistance spectra of Escherichia coli or the bifidobacterial tracking ratio should be investigated locally for potential implementation into the existing monitoring system. The current system could be too costly to implement in certain areas of South Africa where the modified H(2)S strip test might be used as a surrogate for the Colilert®18. PMID:23066390

  9. Microbial Monitoring of Surface Water in South Africa: An Overview

    PubMed Central

    Luyt, Catherine D.; Tandlich, Roman; Muller, Wilhelmine J.; Wilhelmi, Brendan S.

    2012-01-01

    Infrastructural problems force South African households to supplement their drinking water consumption from water resources of inadequate microbial quality. Microbial water quality monitoring is currently based on the Colilert®18 system which leads to rapidly available results. Using Escherichia coli as the indicator microorganism limits the influence of environmental sources on the reported results. The current system allows for understanding of long-term trends of microbial surface water quality and the related public health risks. However, rates of false positive for the Colilert®18-derived concentrations have been reported to range from 7.4% to 36.4%. At the same time, rates of false negative results vary from 3.5% to 12.5%; and the Colilert medium has been reported to provide for cultivation of only 56.8% of relevant strains. Identification of unknown sources of faecal contamination is not currently feasible. Based on literature review, calibration of the antibiotic-resistance spectra of Escherichia coli or the bifidobacterial tracking ratio should be investigated locally for potential implementation into the existing monitoring system. The current system could be too costly to implement in certain areas of South Africa where the modified H2S strip test might be used as a surrogate for the Colilert®18. PMID:23066390

  10. Mapping microbial ecosystems and spoilage-gene flow in breweries highlights patterns of contamination and resistance.

    PubMed

    Bokulich, Nicholas A; Bergsveinson, Jordyn; Ziola, Barry; Mills, David A

    2015-01-01

    Distinct microbial ecosystems have evolved to meet the challenges of indoor environments, shaping the microbial communities that interact most with modern human activities. Microbial transmission in food-processing facilities has an enormous impact on the qualities and healthfulness of foods, beneficially or detrimentally interacting with food products. To explore modes of microbial transmission and spoilage-gene frequency in a commercial food-production scenario, we profiled hop-resistance gene frequencies and bacterial and fungal communities in a brewery. We employed a Bayesian approach for predicting routes of contamination, revealing critical control points for microbial management. Physically mapping microbial populations over time illustrates patterns of dispersal and identifies potential contaminant reservoirs within this environment. Habitual exposure to beer is associated with increased abundance of spoilage genes, predicting greater contamination risk. Elucidating the genetic landscapes of indoor environments poses important practical implications for food-production systems and these concepts are translatable to other built environments. PMID:25756611

  11. Microbial environmental contamination in Italian dental clinics: A multicenter study yielding recommendations for standardized sampling methods and threshold values.

    PubMed

    Pasquarella, Cesira; Veronesi, Licia; Napoli, Christian; Castiglia, Paolo; Liguori, Giorgio; Rizzetto, Rolando; Torre, Ida; Righi, Elena; Farruggia, Patrizia; Tesauro, Marina; Torregrossa, Maria V; Montagna, Maria T; Colucci, Maria E; Gallè, Francesca; Masia, Maria D; Strohmenger, Laura; Bergomi, Margherita; Tinteri, Carola; Panico, Manuela; Pennino, Francesca; Cannova, Lucia; Tanzi, Marialuisa

    2012-03-15

    A microbiological environmental investigation was carried out in ten dental clinics in Italy. Microbial contamination of water, air and surfaces was assessed in each clinic during the five working days, for one week per month, for a three-month period. Water and surfaces were sampled before and after clinical activity; air was sampled before, after, and during clinical activity. A wide variation was found in microbial environmental contamination, both within the participating clinics and for the different sampling times. Before clinical activity, microbial water contamination in tap water reached 51,200cfu/mL (colony forming units per milliliter), and that in Dental Unit Water Systems (DUWSs) reached 872,000cfu/mL. After clinical activity, there was a significant decrease in the Total Viable Count (TVC) in tap water and in DUWSs. Pseudomonas aeruginosa was found in 2.38% (7/294) of tap water samples and in 20.06% (59/294) of DUWS samples; Legionella spp. was found in 29.96% (89/297) of tap water samples and 15.82% (47/297) of DUWS samples, with no significant difference between pre- and post-clinical activity. Microbial air contamination was highest during dental treatments, and decreased significantly at the end of the working activity (p<0.05). The microbial buildup on surfaces increased significantly during the working hours. This study provides data for the establishment of standardized sampling methods, and threshold values for contamination monitoring in dentistry. Some very critical situations have been observed which require urgent intervention. Furthermore, the study emphasizes the need for research aimed at defining effective managing strategies for dental clinics. PMID:22335883

  12. Microbial Contamination of Contact Lenses, Lens Care Solutions, and Their Accessories: A Literature Review

    PubMed Central

    Szczotka-Flynn, Loretta B.; Pearlman, Eric; Ghannoum, Mahmoud

    2012-01-01

    Purpose A contact lens (CL) can act as a vector for microorganisms to adhere to and transfer to the ocular surface. Commensal microorganisms that uneventfully cohabitate on lid margins and conjunctivae and potential pathogens that are found transiently on the ocular surface can inoculate CLs in vivo. In the presence of reduced tissue resistance, these resident microorganisms or transient pathogens can invade and colonize the cornea or conjunctiva to produce inflammation or infection. Methods The literature was reviewed and used to summarize the findings over the last 30 years on the identification, enumeration, and classification of microorganisms adherent to CLs and their accessories during the course of normal wear and to hypothesize the role that these microorganisms play in CL infection and inflammation. Results Lens handling greatly increases the incidence of lens contamination, and the ocular surface has a tremendous ability to destroy organisms. However, even when removed aseptically from the eye, more than half of lenses are found to harbor microorganisms, almost exclusively bacteria. Coagulase-negative Staphylococci are most commonly cultured from worn lenses; however, approximately 10% of lenses harbor Gram-negative and highly pathogenic species, even in asymptomatic subjects. In storage cases, the incidence of positive microbial bioburden is also typically greater than 50%. All types of care solutions can become contaminated, including up to 30% of preserved products. Conclusions The process of CL-related microbial keratitis and inflammation is thought to be preceded by the presence or transfer or both of microorganisms from the lens to the ocular surface. Thus, this detailed understanding of lens-related bioburden is important in the understanding of factors associated with infectious and inflammatory complications. Promising mechanisms to prevent bacterial colonization on lenses and lens cases are forthcoming, which may decrease the incidence of microbially driven CL complications. PMID:20168237

  13. Standardization of surface contamination analysis systems

    NASA Technical Reports Server (NTRS)

    Boothe, Richard E.

    1995-01-01

    Corrosion products, oils and greases can potentially degrade material bonding properties. The Marshall Space Flight Center (MSFC) Surface Contamination Analysis Team (SCAT) utilizes a variety of analytical equipment to detect identify and quantify contamination on metallic and non-metallic substrates. Analysis techniques include FT-IR Microscopy (FT-IR), Near Infrared Optical Fiber Spectrometry (NIR), Optically Stimulated Electron Emission (OSEE), Ultraviolet Fluorescence (UVF) and Ellipsometry. To insure that consistent qualitative and quantitative information are obtained, standards are required to develop analysis techniques, to establish instrument sensitivity to potential contaminants, and to develop calibration curves. This paper describes techniques for preparing and preserving contamination standards. Calibration of surface contamination analysis systems is discussed, and methods are presented for evaluating the effects of potential contaminants on bonding properties.

  14. Remediation of petroleum contaminated soils by joint action of Pharbitis nil L. and its microbial community

    Microsoft Academic Search

    Zhineng Zhang; Qixing Zhou; Shengwei Peng; Zhang Cai

    2010-01-01

    The plot-culture experiments were conducted for examining the feasibility of Pharbitis nil L. and its microbial community to remedy petroleum contaminated soils. The petroleum contaminated soil, containing 10% (w\\/w) of the total petroleum hydrocarbons (TPHs), was collected from the Shengli Oil Field, Dongying City, Shandong Province, China. The collected soil was applied and diluted to a series of petroleum contaminated

  15. Microbial source tracking: a tool for identifying sources of microbial contamination in the food chain.

    PubMed

    Fu, Ling-Lin; Li, Jian-Rong

    2014-01-01

    The ability to trace fecal indicators and food-borne pathogens to the point of origin has major ramifications for food industry, food regulatory agencies, and public health. Such information would enable food producers and processors to better understand sources of contamination and thereby take corrective actions to prevent transmission. Microbial source tracking (MST), which currently is largely focused on determining sources of fecal contamination in waterways, is also providing the scientific community tools for tracking both fecal bacteria and food-borne pathogens contamination in the food chain. Approaches to MST are commonly classified as library-dependent methods (LDMs) or library-independent methods (LIMs). These tools will have widespread applications, including the use for regulatory compliance, pollution remediation, and risk assessment. These tools will reduce the incidence of illness associated with food and water. Our aim in this review is to highlight the use of molecular MST methods in application to understanding the source and transmission of food-borne pathogens. Moreover, the future directions of MST research are also discussed. PMID:24345044

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

    PubMed

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

    2015-03-01

    Microbial attachment to drinking water pipe surfaces facilitates pathogen survival and deteriorates disinfection performance, directly threatening the safety of drinking water. Notwithstanding that the formation of biofilm has been studied for decades, the underlying mechanisms for the origins of microbial surface attachment in biofilm development in drinking water pipelines remain largely elusive. We combined experimental and mathematical methods to investigate the role of environmental stress-mediated cell motility on microbial surface attachment in chlorination-stressed drinking water distribution systems. Results show that at low levels of disinfectant (0.0-1.0 mg/L), the presence of chlorine promotes initiation of microbial surface attachment, while higher amounts of disinfectant (>1.0 mg/L) inhibit microbial attachment. The proposed mathematical model further demonstrates that chlorination stress (0.0-5.0 mg/L)-mediated microbial cell motility regulates the frequency of cell-wall collision and thereby controls initial microbial surface attachment. The results reveal that transport processes and decay patterns of chlorine in drinking water pipelines regulate microbial cell motility and, thus, control initial surface cell attachment. It provides a mechanistic understanding of microbial attachment shaped by environmental disinfection stress and leads to new insights into microbial safety protocols in water distribution systems. PMID:25359474

  17. Device For Sampling Surface Contamination

    NASA Technical Reports Server (NTRS)

    Delgado, Felix A.; Stern, Susan M.

    1995-01-01

    Specially designed cotton swab suitable for use in clean room. Contamination-sampling device improved version of basic cotton-tipped wooden applicator, designed for extreme cleanliness and to enhance utility for sampling according to exacting specifications. Device does not shed cotton and wood fibers.

  18. BIOREMEDIATION OF CONTAMINATED SURFACE SOILS

    EPA Science Inventory

    Biological remediation of soils contaminated with organic chemicals is an alternative treatment technology that can often meet the goal of achieving a permanent clean-up remedy at hazardous waste sites, as encouraged by the U.S. Environmental Protection Agency (U.S. EPA) for impl...

  19. KINETICS OF CHEMICAL & MICROBIAL CONTAMINANTS IN DISTRIBUTION SYSTEMS

    EPA Science Inventory

    Once treated drinking water enters the distribution system, substantial microbial, chemical, and physical changes can occur. Examples of such changes can nclude loss of disinfectant residual, increases in disinfection byproducts (DBP), growth of microbial diversity and population...

  20. MICROBIAL COMMUNITY STRUCTURE IN A SHALLOW HYDROCARBON-CONTAMINATED AQUIFER ASSOCIATED WITH HIGH ELECTRICAL CONDUCTIVITY

    EPA Science Inventory

    Little is known about the complex interactions between microbial communities and electrical properties in contaminated aquifers. In order to investigate possible connections between these parameters a study was undertaken to investigate the hypothesis that the degradation of hydr...

  1. Microbial dynamics during intrinsic remediation of oil contaminated coastal wetland sediments (a microcosm study)

    E-print Network

    Thornburg, Nathaniel David

    2001-01-01

    ) the extent of intrinsic remediation and (ii) if hydrocarbon contamination caused structural changes to chronically exposed microbial communities. MPN statistical analysis revealed that the addition of oil caused 3-fold increases in both aliphatic...

  2. DYNAMICS OF COUPLED CONTAMINANT AND MICROBIAL TRANSPORT IN HETEROGENEOUS POROUS MEDIA

    EPA Science Inventory

    Dynamic microbial attachment/detachment occurs in subsurface systems in response to changing environmental conditions caused by contaminant movement and degradation. Understanding the environmental conditions and mechanisms by which anaerobic bacteria partition between aqueous a...

  3. Distribution of Microbial Physiologic Types in an Aquifer Contaminated by Crude Oil

    Microsoft Academic Search

    B. A. Bekins; E. M. Godsy; E. Warren

    1999-01-01

    We conducted a plume-scale study of the microbial ecology in the anaerobic portion of an aquifer contaminated by crude-oil\\u000a compounds. The data provide insight into the patterns of ecological succession, microbial nutrient demands, and the relative\\u000a importance of free-living versus attached microbial populations. The most probable number (MPN) method was used to characterize\\u000a the spatial distribution of six physiologic types:

  4. Apparatus for measuring surface particulate contamination

    DOEpatents

    Woodmansee, Donald E. (Simpsonville, SC)

    2002-01-01

    An apparatus for measuring surface particulate contamination includes a tool for collecting a contamination sample from a target surface, a mask having an opening of known area formed therein for defining the target surface, and a flexible connector connecting the tool to the mask. The tool includes a body portion having a large diameter section defining a surface and a small diameter section extending from the large diameter section. A particulate collector is removably mounted on the surface of the large diameter section for collecting the contaminants. The tool further includes a spindle extending from the small diameter section and a spool slidingly mounted on the spindle. A spring is disposed between the small diameter section and the spool for biasing the spool away from the small diameter section. An indicator is provided on the spindle so as to be revealed when the spool is pressed downward to compress the spring.

  5. In situ bioremediation of trichloroethy lene- contaminated water by a resting-cell methanotrophic microbial filter

    Microsoft Academic Search

    R. T. TAYLOR; M. L. HANNA; N. N. SHAH; D. R. SHONNARD; J. P. KNEZOVICH; M. C. JOVANOVICH

    1994-01-01

    An in situ microbial filter technology is being tested and deve­ loped for remediating migrating subsurface plumes contaminated with low concentrations of trichloroethy lene (TCE). The current focus is the establishment of a replenishable bioactive zone (catalytic filter) along expanding plume boundaries by the injection of a representative methano­ trophic bacterium, Methylosinus trichosporium OB3b. This microbial filter strategy has been

  6. [Peculiarities of structure-function organization of microbial groups of soil contaminated by cement dust].

    PubMed

    Stefurak, V P

    2001-01-01

    Long-term contamination of the forest soil by the cement dust leads to disturbances of stability of natural microbial groups, changes their quantitative and qualitative composition, results in substitution of some microbial associations by other ones. The intensive contamination of the soil by the effluents of cement integrated works, inhibits the intensity of nitrogen fixation processes and decay of the forest litter, development of micromycetes, results in the decrease of the length of mycelium and its biomass. PMID:11692672

  7. Rapid and reagentless detection of microbial contamination within meat utilizing a smartphone-based biosensor

    NASA Astrophysics Data System (ADS)

    Liang, Pei-Shih; Park, Tu San; Yoon, Jeong-Yeol

    2014-08-01

    A smartphone-utilized biosensor was developed for detecting microbial spoilage on ground beef, without using antibodies, microbeads or any other reagents, towards a preliminary screening tool for microbial contamination on meat products, and potentially towards wound infection. Escherichia coli K12 solutions (101-108 CFU/mL) were added to ground beef products to simulate microbial spoilage. An 880 nm near infrared LED was irradiated perpendicular to the surface of ground beef, and the scatter signals at various angles were evaluated utilizing the gyro sensor and the digital camera of a smartphone. The angle that maximized the Mie scatter varied by the E. coli concentration: 15° for 108 CFU/mL, 30° for 104 CFU/mL, and 45° for 10 CFU/mL, etc. SEM and fluorescence microscopy experiments revealed that the antigens and cell fragments from E. coli bonded preferably to the fat particles within meat, and the size and morphologies of such aggregates varied by the E. coli concentration.

  8. Rapid and reagentless detection of microbial contamination within meat utilizing a smartphone-based biosensor

    PubMed Central

    Liang, Pei-Shih; Park, Tu San; Yoon, Jeong-Yeol

    2014-01-01

    A smartphone-utilized biosensor was developed for detecting microbial spoilage on ground beef, without using antibodies, microbeads or any other reagents, towards a preliminary screening tool for microbial contamination on meat products, and potentially towards wound infection. Escherichia coli K12 solutions (101–108?CFU/mL) were added to ground beef products to simulate microbial spoilage. An 880?nm near infrared LED was irradiated perpendicular to the surface of ground beef, and the scatter signals at various angles were evaluated utilizing the gyro sensor and the digital camera of a smartphone. The angle that maximized the Mie scatter varied by the E. coli concentration: 15° for 108?CFU/mL, 30° for 104?CFU/mL, and 45° for 10?CFU/mL, etc. SEM and fluorescence microscopy experiments revealed that the antigens and cell fragments from E. coli bonded preferably to the fat particles within meat, and the size and morphologies of such aggregates varied by the E. coli concentration. PMID:25092261

  9. Design of a microbial contamination detector and analysis of error sources in its optical path.

    PubMed

    Zhang, Chao; Yu, Xiang; Liu, Xingju; Zhang, Lei

    2014-05-01

    Microbial contamination is a growing concern in the food safety today. To effectively control the types and degree of microbial contamination during food production, this paper introduces a design for a microbial contamination detector that can be used for quick in-situ examination. The designed detector can identify the category of microbial contamination by locating its characteristic absorption peak and then can calculate the concentration of the microbial contamination by fitting the absorbance vs. concentration lines of standard samples with gradient concentrations. Based on traditional scanning grating detection system, this design improves the light splitting unit to expand the scanning range and enhance the accuracy of output wavelength. The motor rotation angle ? is designed to have a linear relationship with the output wavelength angle ?, which simplifies the conversion of output spectral curves into wavelength vs. light intensity curves. In this study, we also derive the relationship between the device's major sources of errors and cumulative error of the output wavelengths, and suggest a simple correction for these errors. The proposed design was applied to test pigments and volatile basic nitrogen (VBN) which evaluated microbial contamination degrees of meats, and the deviations between the measured values and the pre-set values were only in a low range of 1.15% - 1.27%. PMID:24816707

  10. Did surface temperatures constrain microbial evolution?

    NASA Technical Reports Server (NTRS)

    Schwartzman, D.; McMenamin, M.; Volk, T.

    1993-01-01

    The proposition that glaciation may not have occurred before the Cenozoic--albeit not yet a consensus position--nevertheless raises for reconsideration the surface temperature history of the earth. Glacial episodes, from the Huronian (2.3 billion years ago; BYA) through the late Paleozoic (320 to 250 million years ago; MYA) have been critical constraints on estimation of the upper bounds of temperature (Crowley 1983, Kasting and Toon 1989). Once removed, few if any constraints on the upper temperature limit other than life remain. Walker (1982) recognized that life provides an upper limit to temperature in the Precambrian. We propose a more radical concept: the upper temperature limit for viable growth of a given microbial group corresponds to the actual surface temperature at the time of the group's first appearance. In particular, we propose here that two major evolutionary developments--the emergence of cyanobacteria and aerobic eukaryotes--can be used to determine surface temperature in the Precambrian, and that only subsequent cooling mediated by higher plants and then angiosperms permitted what may possibly be the earth's first glaciation in the late Cenozoic.

  11. Calculating Obscuration Ratios Of Contaminated Surfaces

    NASA Technical Reports Server (NTRS)

    Barengoltz, Jack B.

    1989-01-01

    Equations derived to estimate obscuration ratios of surfaces contaminated by particles. Ratio is fraction of surface area covered by particles. Useful as index of cleanliness in clean-room operations in manufacturing of semiconductor devices, magnetic recording media, optical devices, and pharmaceutical and biotechnological products.

  12. Type of closure prevents microbial contamination of cosmetics during consumer use.

    PubMed Central

    Brannan, D K; Dille, J C

    1990-01-01

    The dispensing closure used for containers plays an important role in protecting cosmetics from in-use microbial contamination. This hypothesis was tested by aseptically packing unpreserved shampoo and skin lotion into containers with three different closure types which provided various degrees of protection against consumer and environmental microbial insults. Shampoo was packed in containers with slit-cap (n = 25), flip-cap (n = 25), or screw-cap (n = 28) closures. Skin lotion was packed in containers with pump-top (n = 21), flip-cap (n = 18), or screw-cap (n = 21) closures. The products were then used by volunteers under actual in-use conditions for 3 (shampoo) or 2 (skin lotion) weeks. After use, the products were evaluated for microbial contamination by using standard methods for enumeration and identification. The standard screw-cap closure provided only minimal protection against microbial contamination of both the shampoo (29% contamination incidence) and the skin lotion (71%). The slit-cap closure on the shampoo container and the flip-cap closure on the skin lotion container provided slightly enhanced degrees of protection (21 and 39% contamination incidence, respectively). The greatest amount of protection (i.e., lowest contamination incidence) was provided by the flip-cap closure for the shampoo container (0%) and the pump-top closure for the skin lotion container (10%). As a result, closure type plays an important role in protecting poorly preserved products from in-use microbial contamination. Images PMID:2339896

  13. Microbially Induced Calcite Precipitation for Subsurface Immobilization of Contaminants

    NASA Astrophysics Data System (ADS)

    Smith, R. W.; Fujita, Y.; Ginn, T. R.; Hubbard, S. S.; Dafflon, B.; Delwiche, M.; Gebrehiwet, T.; Henriksen, J. R.; Peterson, J.; Taylor, J. L.

    2011-12-01

    Subsurface radionuclide and metal contaminants throughout the U.S. Department of Energy (DOE) complex pose one of the greatest challenges for long-term stewardship. One promising stabilization mechanism for divalent trace ions, such as the short-lived radionuclide 90Sr, is co-precipitation in calcite. We have found that calcite precipitation and co-precipitation of Sr can be accelerated by the activity of urea hydrolyzing microorganisms, that higher calcite precipitation rates can result in increased Sr partitioning, and that nutrient additions can stimulate ureolytic activity. To extend our understanding of microbially induced calcite precipitation (MICP) in an aquifer setting a continuous recirculation field experiment evaluating MICP was conducted at the Integrated Field Research Challenge (IFRC) site located at Rifle, CO. In this experiment, groundwater extracted from an onsite well was amended with urea (total mass of 42.5 kg) and molasses (a carbon and electron donor) and re-injected into a well approximately 4 meters up-gradient for a period of 12 days followed by 10 months of groundwater sampling and monitoring. Crosshole radar and electrical tomographic data were collected prior, during, and after the MICP treatment. The urea and molasses treatment resulted in an enhanced population of sediment associated urea hydrolyzing organisms as evidenced by increases in the number of ureC gene copies, increases in 14C urea hydrolysis rates, and long-term observations of ammonium (a urea hydrolysis product) in the injection, extraction and down gradient monitoring wells. Permeability changes and increases in the calcite saturation indexes in the well field suggest that mineral precipitation has occurred; ongoing analysis of field samples seeks to confirm this. Changes in dielectric constant and electrical conductivity were used to interpret the spatiotemporal distribution of the injectate and subsequent calcite precipitation. Modeling activities are underway to define field-scale urea hydrolysis rates.

  14. Microbial changes in rhizospheric soils contaminated with petroleum hydrocarbons after bioremediation.

    PubMed

    Lin, Xin; Li, Pei-Jun; Zhou, Qi-Xing; Xu, Hua-Xia; Zhang, Hai-Rong

    2004-01-01

    Effects of bioremediation on microbial communities in soils contaminated with petroleum hydrocarbons are a scientific problem to be solved. Changes in dominate microbial species and the total amount of microorganisms including bacteria and fungi in rhizospheric soils after bioremediation were thus evaluated using field bioremediation experiments. The results showed that there were changed dominant microorganisms including 11 bacterial strains which are mostly Gram positive bacteria and 6 fungal species which were identified. The total amount of microorganisms including bacteria and fungi increased after bioremediation of microbial agents combined with planting maize. On the contrary, fungi in rhizospheric soils were inhibited by adding microbial agents combined with planting soybean. PMID:15900734

  15. Effect of surface contamination on solid phase welding: an overview

    Microsoft Academic Search

    1978-01-01

    Surface contaminants hinder solid phase welding by not allowing metallic surfaces to be brought sufficiently close together that short range interatomic attractive forces operate. The effect of surface contamination on solid phase welding is worse than implied by viewing contaminants simply as physical barriers to adhesion because surface metallic atoms become satisfied by forming bonds with contaminant atoms, thus reducing

  16. Relating groundwater and sediment chemistry to microbial characterization at a BTEX-contaminated site

    SciTech Connect

    Pfiffner, S.M.; Palumbo, A.V.; McCarthy, J.F. [Oak Ridge National Lab., TN (United States); Gibson, T. [General Motors Research and Development Center, Warren, MI (United States)] [and others

    1996-07-01

    The National Center for Manufacturing Science is investigating bioremediation of petroleum hydrocarbon at a site in Belleville, Michigan. As part of this study we examined the microbial communities to help elucidate biodegradative processes currently active at the site. We observed high densities of aerobic hydrocarbon degraders and denitrifiers in the less-contaminated sediments. Low densities of iron and sulfate reducers were measured in the same sediments. In contrast, the highly-contaminated sediments showed low densities of aerobic hydrocarbon degraders and denitrifiers and high densities of iron and sulfate reducers. Methanogens were also found in these highly-contaminated sediments. These contaminated sediments also showed a higher biomass, by phospholipid fatty acids, and greater ratios of phospholipid fatty acids which indicate stress within the microbial community. Aquifer chemistry analyses indicated that the more-contaminated area was more reduced and had lower sulfate than the less-contaminated area. These conditions suggest that the subsurface environment at the highly-contaminated area had progressed into sulfate reduction and methanogensis. The less-contaminated area, although less reduced, also appeared to be progressing into primarily iron- and sulfate-reducing microbial communities. The proposed treatment to stimulate bioremediation includes addition of oxygen and nitrate. Groundwater chemistry and microbial analyses revealed significant differences resulted from the injection of dissolved oxygen and nitrate in the subsurface. These differences included increases in pH and Eh and large decreases in BTEX, dissolved iron, and sulfate concentrations at the injection well.

  17. Effect of Microbially Induced Anoxia on Cr(VI) Mobility at a Site Contaminated with Hyperalkaline Residue from Chromite Ore Processing

    Microsoft Academic Search

    R. A. Whittleston; D. I. Stewart; R. J. G. Mortimer; D. J. Ashley; I. T. Burke

    2011-01-01

    This paper reports an investigation of microbially mediated Cr(VI) reduction in a hyperalkaline, chromium-contaminated soil-water system representative of the conditions at a chromite ore processing residue (COPR) site. Soil from the former surface layer that has been buried beneath a COPR tip for over 100 years was shown to have an active microbial population despite a pH value of 10.5.

  18. Immunological techniques as tools to characterize the subsurface microbial community at a trichloroethylene contaminated site

    SciTech Connect

    Fliermans, C.B.; Dougherty, J.M.; Franck, M.M.; McKinzey, P.C.; Hazen, T.C.

    1992-12-31

    Effective in situ bioremediation strategies require an understanding of the effects pollutants and remediation techniques have on subsurface microbial communities. Therefore, detailed characterization of a site`s microbial communities is important. Subsurface sediment borings and water samples were collected from a trichloroethylene (TCE) contaminated site, before and after horizontal well in situ air stripping and bioventing, as well as during methane injection for stimulation of methane-utilizing microorganisms. Subsamples were processed for heterotrophic plate counts, acridine orange direct counts (AODC), community diversity, direct fluorescent antibodies (DFA) enumeration for several nitrogen-transforming bacteria, and Biolog {reg_sign} evaluation of enzyme activity in collected water samples. Plate counts were higher in near-surface depths than in the vadose zone sediment samples. During the in situ air stripping and bioventing, counts increased at or near the saturated zone, remained elevated throughout the aquifer, but did not change significantly after the air stripping. Sporadic increases in plate counts at different depths as well as increased diversity appeared to be linked to differing lithologies. AODCs were orders of magnitude higher than plate counts and remained relatively constant with depth except for slight increases near the surface depths and the capillary fringe. Nitrogen-transforming bacteria, as measured by serospecific DFA, were greatly affected both by the in situ air stripping and the methane injection. Biolog{reg_sign} activity appeared to increase with subsurface stimulation both by air and methane. The complexity of subsurface systems makes the use of selective monitoring tools imperative.

  19. Immunological techniques as tools to characterize the subsurface microbial community at a trichloroethylene contaminated site

    SciTech Connect

    Fliermans, C.B.; Dougherty, J.M.; Franck, M.M.; McKinzey, P.C.; Hazen, T.C.

    1992-01-01

    Effective in situ bioremediation strategies require an understanding of the effects pollutants and remediation techniques have on subsurface microbial communities. Therefore, detailed characterization of a site's microbial communities is important. Subsurface sediment borings and water samples were collected from a trichloroethylene (TCE) contaminated site, before and after horizontal well in situ air stripping and bioventing, as well as during methane injection for stimulation of methane-utilizing microorganisms. Subsamples were processed for heterotrophic plate counts, acridine orange direct counts (AODC), community diversity, direct fluorescent antibodies (DFA) enumeration for several nitrogen-transforming bacteria, and Biolog [reg sign] evaluation of enzyme activity in collected water samples. Plate counts were higher in near-surface depths than in the vadose zone sediment samples. During the in situ air stripping and bioventing, counts increased at or near the saturated zone, remained elevated throughout the aquifer, but did not change significantly after the air stripping. Sporadic increases in plate counts at different depths as well as increased diversity appeared to be linked to differing lithologies. AODCs were orders of magnitude higher than plate counts and remained relatively constant with depth except for slight increases near the surface depths and the capillary fringe. Nitrogen-transforming bacteria, as measured by serospecific DFA, were greatly affected both by the in situ air stripping and the methane injection. Biolog[reg sign] activity appeared to increase with subsurface stimulation both by air and methane. The complexity of subsurface systems makes the use of selective monitoring tools imperative.

  20. Assessment of metals distribution and microbial contamination at selected lake waters in and around Miri City, East Malaysia.

    PubMed

    Prasanna, M V; Nagarajan, R; Chidambaram, S; Elayaraja, A

    2012-09-01

    A baseline study was carried out to assess the metal concentrations and microbial contamination at selected Lake waters in and around Miri City, East Malaysia. Sixteen surface water samples were collected at specific Lakes in the environs of major settlement areas and recreational centers in Miri City. The Physico-chemical parameters [pH, Electrical Conductivity (EC) and Dissolved Oxygen (DO)], metals (Fe, Mn, Cu, Cd, Ni and Zn) and Escherichia coli (E. coli) were analysed. The concentrations of Fe, Mn and Ni have been found to be above the permissible limits of drinking water quality standards. The metals data have also been used for the calculation of heavy metal pollution index. Higher values of E. coli indicate microbial contamination in the Lake waters. PMID:22684361

  1. Relating ground water and sediment chemistry to microbial characterization at a BTEX-contaminated site.

    PubMed

    Pfiffner, S M; Palumbo, A V; Gibson, T; Ringelberg, D B; McCarthy, J F

    1997-01-01

    The National Center for Manufacturing Science is investigating bioremediation of petroleum hydrocarbon at a site near Belleville, MI. As part of this study, we examined the microbial communities to help elucidate biodegradative processes currently active at the site. We observed high densities of aerobic hydrocarbon degraders and denitrifiers in the less-contaminated sediments. Low densities of iron and sulfate reducers were measured in the same sediments. In contrast, the highly contaminated sediments showed low densities of aerobic hydrocarbon degraders and denitrifiers, and high densities of iron and sulfate reducers. Methanogens were also found in these highly contaminated sediments. These contaminated sediments also showed a higher biomass, by the phospholipid fatty acids, and greater ratios of phospholipid fatty acids, which indicate stress within the microbial community. Aquifer chemistry analyses indicated that the highly contaminated area was more reduced and had lower sulfate than the less-contaminated area. These conditions suggest that the subsurface environment at the highly contaminated area had progressed into sulfate reduction and methanogenesis. The less-contaminated area, although less reduced, also appeared to be progressing into primarily iron- and sulfate-reducing microbial communities. The proposed treatment to stimulate bioremediation includes addition of oxygen and nitrate to the subsurface. Ground water chemistry and microbial analyses revealed significant differences that resulted from the injection of dissolved oxygen and nitrate. These differences included an increase in Eh, small decrease in pH, and large decreases in BTEX, dissolved iron, and sulfate concentrations at the injection well. Injected nitrate was rapidly utilized by the subsurface microbial communities, and significant nitrite amounts were observed in the injection well and in nearby down-gradient observation wells. Microbial and molecular analyses indicated an increase in denitrifying bacteria after nitrate injection. The activity and population of denitrifying bacteria were significantly increased at the injection well relative to a down-gradient well for as long as 2 mo after the nitrate injection ended. PMID:18576131

  2. The Microbial Community Structure in Petroleum-Contaminated Sediments Corresponds to Geophysical Signatures? †

    PubMed Central

    Allen, Jonathan P.; Atekwana, Estella A.; Atekwana, Eliot A.; Duris, Joseph W.; Werkema, D. Dale; Rossbach, Silvia

    2007-01-01

    The interdependence between geoelectrical signatures at underground petroleum plumes and the structures of subsurface microbial communities was investigated. For sediments contaminated with light non-aqueous-phase liquids, anomalous high conductivity values have been observed. Vertical changes in the geoelectrical properties of the sediments were concomitant with significant changes in the microbial community structures as determined by the construction and evaluation of 16S rRNA gene libraries. DNA sequencing of clones from four 16S rRNA gene libraries from different depths of a contaminated field site and two libraries from an uncontaminated background site revealed spatial heterogeneity in the microbial community structures. Correspondence analysis showed that the presence of distinct microbial populations, including the various hydrocarbon-degrading, syntrophic, sulfate-reducing, and dissimilatory-iron-reducing populations, was a contributing factor to the elevated geoelectrical measurements. Thus, through their growth and metabolic activities, microbial populations that have adapted to the use of petroleum as a carbon source can strongly influence their geophysical surroundings. Since changes in the geophysical properties of contaminated sediments parallel changes in the microbial community compositions, it is suggested that geoelectrical measurements can be a cost-efficient tool to guide microbiological sampling for microbial ecology studies during the monitoring of natural or engineered bioremediation processes. PMID:17351087

  3. Insect contamination protection for laminar flow surfaces

    NASA Technical Reports Server (NTRS)

    Croom, Cynthia C.; Holmes, Bruce J.

    1986-01-01

    The ability of modern aircraft surfaces to achieve laminar flow was well-accepted in recent years. Obtaining the maximum benefit of laminar flow for aircraft drag reduction requires maintaining minimum leading-edge contamination. Previously proposed insect contamination prevention methods have proved impractical due to cost, weight, or inconvenience. Past work has shown that insects will not adhere to water-wetted surfaces, but the large volumes of water required for protection rendered such a system impractical. The results of a flight experiment conducted by NASA to evaluate the performance of a porous leading-edge fluid discharge ice protection system operated as an insect contamination protections system are presented. In addition, these flights explored the environmental and atmospheric conditions most suitable for insect accumulation.

  4. Leakage current patterns on contaminated polymeric surfaces

    Microsoft Academic Search

    M. A. R. M. Fernando; S. M. Gubanski

    1999-01-01

    This paper presents measurements of low-level leakage current (LC) patterns on naturally aged insulators and artificially contaminated material samples as well as insulators. A nonlinear behavior of the LC has been observed. Possible causes for this behavior are discussed and its relations to surface hydrophobicity and electric stress are described. In addition, neural networks are trained to recognize the LC

  5. Microbial biomass and activity in lead-contaminated soil

    SciTech Connect

    Konopka, A.; Zakharova, T.; Bischoff, M.; Oliver, L.; Nakatsu, C.; Turco, R.F. [Purdue Univ., West Lafayette, IN (United States)

    1999-05-01

    Microbial community diversity, potential microbial activity, and metal resistance were determined in three soils whose lead contents ranged from 0.00039 to 48 mmol of Pb kg of soil{sup {minus}1}. Biomass levels were directly related to lead content. A molecular analysis of 16S rRNAs suggested that each soil contained a complex, diverse microbial community. A statistical analysis of the phospholipid fatty acids indicated that the community in the soil having the highest lead content was not related to the communities in the other soils. All of the soils contained active microbial populations that mineralized [{sup 14}C]glucose. In all samples, 10 to 15% of the total culturable bacteria were Pb resistant and had MCI of Pb for growth of 100 to 150 {micro}M.

  6. Relating ground water and sediment chemistry to microbial characterization at a BTEX-contaminated site

    SciTech Connect

    Pfiffner, S.M.; Palumbo, A.V.; McCarthy, J.F. [Oak Ridge National Lab., TN (United States)] [and others

    1997-12-31

    The National Center for Manufacturing Science is investigating bioremediation of petroleum hydrocarbon at a site near Belleville, MI. As part of this study, we examined the microbial communities to help elucidate biodegradative processes currently active at the site. We observed high densities of aerobic hydrocarbon degraders and denitrifiers in the less-contaminated sediments. Low densities of iron and sulfate reducers were measured in the same sediments. In contrast, the highly contaminated sediments showed low densities of aerobic hydrocarbon degraders and denitrifiers, and high densities of iron and sulfate reducers. Methanogens were also found in these highly contaminated sediments. These contaminated sediments also showed a higher biomass, by the phospholipid fatty acids, and greater ratios of phospholipid fatty acids, which indicate stress within the microbial community. Aquifer chemistry analyses indicated that the highly contaminated area was more reduced and had lower sulfate than the less-contaminated area. These conditions suggest that the subsurface environment at the highly contaminated area had progressed into sulfate reduction and methanogenesis. The less-contaminated area, although less reduced, also appeared to be progressing into primarily iron- and sulfate-reducing microbial communities. The proposed treatment to stimulate bioremediation includes addition of oxygen and nitrate to the subsurface. 24 refs., 5 figs., 3 tabs.

  7. Application of electrokinetics for stimulating microbial clean-up of contaminated soils

    NASA Astrophysics Data System (ADS)

    Thompson, I.; Lear, G.

    2006-05-01

    Given sufficient time there are few synthetic compounds that can resist microbial degradation, a fact exploited in environmental clean-up. Despite this the performance of micro-organisms in remedial technologies is often sub-optimal. There are many reasons for the failure of indigenous microbial communities to reduce contaminant concentrations, including issues of bioavailability and the inability of the contaminants to switch on genes (catabolic) responsible for contaminant degradation. Even if the presence of the required catabolic genes is confirmed, there continues to be a significant need to develop procedures to stimulate their activity. We have investigated the potential of soil electrokinetics (3-4 A m-2) to stimulate microbial degradation of organic pollutants and move the soil contaminants relative to the degradative microorganisms, so increasing contact between the two components. Using soils contaminated with pentachlorophenol as our model laboratory system, we have demonstrated that the technique is effective at causing gross and controlled movement of PCP through soils at the laboratory-scale. It can also stimulate rates (up to 25% over that of the control) by which introduced bacteria degrade the contaminant. The additional potential benefits of electrokinetics in regard to stimulating microbial activity and soil clean-up will be discussed.

  8. Sustainable remediation: electrochemically assisted microbial dechlorination of tetrachloroethene-contaminated groundwater.

    PubMed

    Patil, Sayali S; Adetutu, Eric M; Rochow, Jacqueline; Mitchell, James G; Ball, Andrew S

    2014-01-01

    Microbial electric systems (MESs) hold significant promise for the sustainable remediation of chlorinated solvents such as tetrachlorethene (perchloroethylene, PCE). Although the bio-electrochemical potential of some specific bacterial species such as Dehalcoccoides and Geobacteraceae have been exploited, this ability in other undefined microorganisms has not been extensively assessed. Hence, the focus of this study was to investigate indigenous and potentially bio-electrochemically active microorganisms in PCE-contaminated groundwater. Lab-scale MESs were fed with acetate and carbon electrode/PCE as electron donors and acceptors, respectively, under biostimulation (BS) and BS-bioaugmentation (BS-BA) regimes. Molecular analysis of the indigenous groundwater community identified mainly Spirochaetes, Firmicutes, Bacteroidetes, and ? and ?-Proteobacteria. Environmental scanning electron photomicrographs of the anode surfaces showed extensive indigenous microbial colonization under both regimes. This colonization and BS resulted in 100% dechlorination in both treatments with complete dechlorination occurring 4 weeks earlier in BS-BA samples and up to 11.5??A of current being generated. The indigenous non-Dehalococcoides community was found to contribute significantly to electron transfer with ?61% of the current generated due to their activities. This study therefore shows the potential of the indigenous non-Dehalococcoides bacterial community in bio-electrochemically reducing PCE that could prove to be a cost-effective and sustainable bioremediation practice. PMID:24119162

  9. Sustainable remediation: electrochemically assisted microbial dechlorination of tetrachloroethene-contaminated groundwater

    PubMed Central

    Patil, Sayali S; Adetutu, Eric M; Rochow, Jacqueline; Mitchell, James G; Ball, Andrew S

    2014-01-01

    Microbial electric systems (MESs) hold significant promise for the sustainable remediation of chlorinated solvents such as tetrachlorethene (perchloroethylene, PCE). Although the bio-electrochemical potential of some specific bacterial species such as Dehalcoccoides and Geobacteraceae have been exploited, this ability in other undefined microorganisms has not been extensively assessed. Hence, the focus of this study was to investigate indigenous and potentially bio-electrochemically active microorganisms in PCE-contaminated groundwater. Lab-scale MESs were fed with acetate and carbon electrode/PCE as electron donors and acceptors, respectively, under biostimulation (BS) and BS-bioaugmentation (BS-BA) regimes. Molecular analysis of the indigenous groundwater community identified mainly Spirochaetes, Firmicutes, Bacteroidetes, and ? and ?-Proteobacteria. Environmental scanning electron photomicrographs of the anode surfaces showed extensive indigenous microbial colonization under both regimes. This colonization and BS resulted in 100% dechlorination in both treatments with complete dechlorination occurring 4 weeks earlier in BS-BA samples and up to 11.5 ?A of current being generated. The indigenous non-Dehalococcoides community was found to contribute significantly to electron transfer with ?61% of the current generated due to their activities. This study therefore shows the potential of the indigenous non-Dehalococcoides bacterial community in bio-electrochemically reducing PCE that could prove to be a cost-effective and sustainable bioremediation practice. PMID:24119162

  10. Mapping microbial ecosystems and spoilage-gene flow in breweries highlights patterns of contamination and resistance

    PubMed Central

    Bokulich, Nicholas A; Bergsveinson, Jordyn; Ziola, Barry; Mills, David A

    2015-01-01

    Distinct microbial ecosystems have evolved to meet the challenges of indoor environments, shaping the microbial communities that interact most with modern human activities. Microbial transmission in food-processing facilities has an enormous impact on the qualities and healthfulness of foods, beneficially or detrimentally interacting with food products. To explore modes of microbial transmission and spoilage-gene frequency in a commercial food-production scenario, we profiled hop-resistance gene frequencies and bacterial and fungal communities in a brewery. We employed a Bayesian approach for predicting routes of contamination, revealing critical control points for microbial management. Physically mapping microbial populations over time illustrates patterns of dispersal and identifies potential contaminant reservoirs within this environment. Habitual exposure to beer is associated with increased abundance of spoilage genes, predicting greater contamination risk. Elucidating the genetic landscapes of indoor environments poses important practical implications for food-production systems and these concepts are translatable to other built environments. DOI: http://dx.doi.org/10.7554/eLife.04634.001 PMID:25756611

  11. Hard Surface Biocontrol in Hospitals Using Microbial-Based Cleaning Products

    PubMed Central

    Vandini, Alberta; Temmerman, Robin; Frabetti, Alessia; Caselli, Elisabetta; Antonioli, Paola; Balboni, Pier Giorgio; Platano, Daniela; Branchini, Alessio; Mazzacane, Sante

    2014-01-01

    Background Healthcare-Associated Infections (HAIs) are one of the most frequent complications occurring in healthcare facilities. Contaminated environmental surfaces provide an important potential source for transmission of many healthcare-associated pathogens, thus indicating the need for new and sustainable strategies. Aim This study aims to evaluate the effect of a novel cleaning procedure based on the mechanism of biocontrol, on the presence and survival of several microorganisms responsible for HAIs (i.e. coliforms, Staphyloccus aureus, Clostridium difficile, and Candida albicans) on hard surfaces in a hospital setting. Methods The effect of microbial cleaning, containing spores of food grade Bacillus subtilis, Bacillus pumilus and Bacillus megaterium, in comparison with conventional cleaning protocols, was evaluated for 24 weeks in three independent hospitals (one in Belgium and two in Italy) and approximately 20000 microbial surface samples were collected. Results Microbial cleaning, as part of the daily cleaning protocol, resulted in a reduction of HAI-related pathogens by 50 to 89%. This effect was achieved after 3–4 weeks and the reduction in the pathogen load was stable over time. Moreover, by using microbial or conventional cleaning alternatively, we found that this effect was directly related to the new procedure, as indicated by the raise in CFU/m2 when microbial cleaning was replaced by the conventional procedure. Although many questions remain regarding the actual mechanisms involved, this study demonstrates that microbial cleaning is a more effective and sustainable alternative to chemical cleaning and non-specific disinfection in healthcare facilities. Conclusions This study indicates microbial cleaning as an effective strategy in continuously lowering the number of HAI-related microorganisms on surfaces. The first indications on the actual level of HAIs in the trial hospitals monitored on a continuous basis are very promising, and may pave the way for a novel and cost-effective strategy to counteract or (bio)control healthcare-associated pathogens. PMID:25259528

  12. Microbial expression profiles in the rhizosphere of willows depend on soil contamination

    PubMed Central

    Yergeau, Etienne; Sanschagrin, Sylvie; Maynard, Christine; St-Arnaud, Marc; Greer, Charles W

    2014-01-01

    The goal of phytoremediation is to use plants to immobilize, extract or degrade organic and inorganic pollutants. In the case of organic contaminants, plants essentially act indirectly through the stimulation of rhizosphere microorganisms. A detailed understanding of the effect plants have on the activities of rhizosphere microorganisms could help optimize phytoremediation systems and enhance their use. In this study, willows were planted in contaminated and non-contaminated soils in a greenhouse, and the active microbial communities and the expression of functional genes in the rhizosphere and bulk soil were compared. Ion Torrent sequencing of 16S rRNA and Illumina sequencing of mRNA were performed. Genes related to carbon and amino-acid uptake and utilization were upregulated in the willow rhizosphere, providing indirect evidence of the compositional content of the root exudates. Related to this increased nutrient input, several microbial taxa showed a significant increase in activity in the rhizosphere. The extent of the rhizosphere stimulation varied markedly with soil contamination levels. The combined selective pressure of contaminants and rhizosphere resulted in higher expression of genes related to competition (antibiotic resistance and biofilm formation) in the contaminated rhizosphere. Genes related to hydrocarbon degradation were generally more expressed in contaminated soils, but the exact complement of genes induced was different for bulk and rhizosphere soils. Together, these results provide an unprecedented view of microbial gene expression in the plant rhizosphere during phytoremediation. PMID:24067257

  13. Microbial expression profiles in the rhizosphere of willows depend on soil contamination.

    PubMed

    Yergeau, Etienne; Sanschagrin, Sylvie; Maynard, Christine; St-Arnaud, Marc; Greer, Charles W

    2014-02-01

    The goal of phytoremediation is to use plants to immobilize, extract or degrade organic and inorganic pollutants. In the case of organic contaminants, plants essentially act indirectly through the stimulation of rhizosphere microorganisms. A detailed understanding of the effect plants have on the activities of rhizosphere microorganisms could help optimize phytoremediation systems and enhance their use. In this study, willows were planted in contaminated and non-contaminated soils in a greenhouse, and the active microbial communities and the expression of functional genes in the rhizosphere and bulk soil were compared. Ion Torrent sequencing of 16S rRNA and Illumina sequencing of mRNA were performed. Genes related to carbon and amino-acid uptake and utilization were upregulated in the willow rhizosphere, providing indirect evidence of the compositional content of the root exudates. Related to this increased nutrient input, several microbial taxa showed a significant increase in activity in the rhizosphere. The extent of the rhizosphere stimulation varied markedly with soil contamination levels. The combined selective pressure of contaminants and rhizosphere resulted in higher expression of genes related to competition (antibiotic resistance and biofilm formation) in the contaminated rhizosphere. Genes related to hydrocarbon degradation were generally more expressed in contaminated soils, but the exact complement of genes induced was different for bulk and rhizosphere soils. Together, these results provide an unprecedented view of microbial gene expression in the plant rhizosphere during phytoremediation. PMID:24067257

  14. Microbial community structure and function in a soil contaminated by heavy metals: effects of plant growth and different amendments

    Microsoft Academic Search

    Alfredo Pérez-de-Mora; Pilar Burgos; Engracia Madejón; Francisco Cabrera; Petra Jaeckel; Michael Schloter

    2006-01-01

    We studied the effects of in situ remediation of a heavy metal (HM) contaminated soil on some soil chemical properties, microbial function and microbial structural diversity after 18 months. The experiment was carried out at semifield scale in containers filled with HM contaminated soil from the Aznalcóllar mine accident (Southern Spain, 1998). The remediation measures consisted of the application of

  15. Surface contamination analysis technology team overview

    NASA Technical Reports Server (NTRS)

    Burns, H. Dewitt

    1995-01-01

    A team was established which consisted of representatives from NASA (Marshall Space Flight Center and Langley Research Center), Thiokol Corporation, the University of Alabama in Huntsville, AC Engineering, SAIC, Martin Marietta, and Aerojet. The team's purpose was to bring together the appropriate personnel to determine what surface inspection techniques were applicable to multiprogram bonding surface cleanliness inspection. In order to identify appropriate techniques and their sensitivity to various contaminant families, calibration standards were developed. Producing standards included development of consistent low level contamination application techniques. Oxidation was also considered for effect on inspection equipment response. Ellipsometry was used for oxidation characterization. Verification testing was then accomplished to show that selected inspection techniques could detect subject contaminants at levels found to be detrimental to critical bond systems of interest. Once feasibility of identified techniques was shown, selected techniques and instrumentation could then be incorporated into a multipurpose inspection head and integrated with a robot for critical surface inspection. Inspection techniques currently being evaluated include optically stimulated electron emission (OSEE); near infrared (NIR) spectroscopy utilizing fiber optics; Fourier transform infrared (FTIR) spectroscopy; and ultraviolet (UV) fluorescence. Current plans are to demonstrate an integrated system in MSFC's Productivity Enhancement Complex within five years from initiation of this effort in 1992 assuming appropriate funding levels are maintained. This paper gives an overview of work accomplished by the team and future plans.

  16. Microbial studies of a selenium-contaminated mine site and potential for on-site remediation

    Microsoft Academic Search

    Heather M. Knotek-Smith; Don L. Crawford; Gregory Möller; Rachel A. Henson

    2006-01-01

    Surface water Selenium (Se) concentrations are above regulatory standards at several active and inactive phosphate mine sites in the US Western Phosphate Resource Area. The focus of the present study was to examine the impacts of the microbial communities on the oxidation state of Se in overburden waste from the Smoky Canyon phosphate mine in Idaho, USA. Microbial populations were

  17. 10 CFR Appendix D to Part 835 - Surface Contamination Values

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 false Surface Contamination Values D Appendix D to Part 835 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Pt. 835, App. D Appendix D to Part 835—Surface Contamination...

  18. 10 CFR Appendix D to Part 835 - Surface Contamination Values

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 2011-01-01 false Surface Contamination Values D Appendix D to Part 835 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Pt. 835, App. D Appendix D to Part 835—Surface Contamination...

  19. 10 CFR Appendix D to Part 835 - Surface Contamination Values

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 false Surface Contamination Values D Appendix D to Part 835 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Pt. 835, App. D Appendix D to Part 835—Surface Contamination...

  20. The important role of sink location in handwashing compliance and microbial sink contamination.

    PubMed

    Cloutman-Green, Elaine; Kalaycioglu, Oya; Wojani, Hedieh; Hartley, John C; Guillas, Serge; Malone, Deirdre; Gant, Vanya; Grey, Colin; Klein, Nigel

    2014-05-01

    Handwashing is one of the most important means of reducing the spread of infection. In this study, we investigated how sink location and visibility influences handwashing and microbial contamination detected on clinical sinks in 3 pediatric intensive care units. We conclude that the visibility of sinks directly impacts on handwashing frequency and duration and also impacts on levels of bacterial contamination on and around the sink area. PMID:24773795

  1. Microbial Degradation of Petroleum Hydrocarbon Contaminants: An Overview

    PubMed Central

    Das, Nilanjana; Chandran, Preethy

    2011-01-01

    One of the major environmental problems today is hydrocarbon contamination resulting from the activities related to the petrochemical industry. Accidental releases of petroleum products are of particular concern in the environment. Hydrocarbon components have been known to belong to the family of carcinogens and neurotoxic organic pollutants. Currently accepted disposal methods of incineration or burial insecure landfills can become prohibitively expensive when amounts of contaminants are large. Mechanical and chemical methods generally used to remove hydrocarbons from contaminated sites have limited effectiveness and can be expensive. Bioremediation is the promising technology for the treatment of these contaminated sites since it is cost-effective and will lead to complete mineralization. Bioremediation functions basically on biodegradation, which may refer to complete mineralization of organic contaminants into carbon dioxide, water, inorganic compounds, and cell protein or transformation of complex organic contaminants to other simpler organic compounds by biological agents like microorganisms. Many indigenous microorganisms in water and soil are capable of degrading hydrocarbon contaminants. This paper presents an updated overview of petroleum hydrocarbon degradation by microorganisms under different ecosystems. PMID:21350672

  2. Characterizing public health and microbial risks due to water contaminants

    EPA Science Inventory

    This research track evaluates risks associated with the occurrence of waterborne disease in the population. A clear understanding of the health burden associated with exposure to contaminated drinking water is critical to developing regulations that are protective of public healt...

  3. Microbial controls on contaminant metal transport in porous media 

    E-print Network

    Kapetas, Leon

    2011-11-24

    Metal contamination in groundwater aquifers poses risks to human health as well as other life forms. Previous laboratory experiments have demonstrated that bacteria found in geologic settings like aquifers are likely to ...

  4. Rapid and Robust Detection Methods for Poison and Microbial Contamination

    E-print Network

    Lu, Peter J.

    Real-time on-site monitoring of analytes is currently in high demand for food contamination, water, medicines, and ingestible household products that were never tested appropriately. Here we introduce chemical methods for ...

  5. Surface contamination monitoring by the measurement of scattering distribution functions

    Microsoft Academic Search

    Paola A. Carosso; Nancy J. Pugel

    1987-01-01

    This paper describes the use of Bidirectional Scattering Distribution Functions (BSDF) to quantify surface degradation, thus providing an effective method for contamination monitoring. This approach to contamination monitoring is based on the use of witness surfaces (mirrors or glass slides) located next to the critical surfaces. Contaminant accretion can be monitored during all phases of spacecraft fabrication, assembly, and testing.

  6. Assessing the Microbial Community and Functional Genes in a Vertical Soil Profile with Long-Term Arsenic Contamination

    PubMed Central

    Xiong, Jinbo; He, Zhili; Van Nostrand, Joy D.; Luo, Guosheng; Tu, Shuxin; Zhou, Jizhong; Wang, Gejiao

    2012-01-01

    Arsenic (As) contamination in soil and groundwater has become a serious problem to public health. To examine how microbial communities and functional genes respond to long-term arsenic contamination in vertical soil profile, soil samples were collected from the surface to the depth of 4 m (with an interval of 1 m) after 16-year arsenic downward infiltration. Integrating BioLog and functional gene microarray (GeoChip 3.0) technologies, we showed that microbial metabolic potential and diversity substantially decreased, and community structure was markedly distinct along the depth. Variations in microbial community functional genes, including genes responsible for As resistance, carbon and nitrogen cycling, phosphorus utilization and cytochrome c oxidases were detected. In particular, changes in community structures and activities were correlated with the biogeochemical features along the vertical soil profile when using the rbcL and nifH genes as biomarkers, evident for a gradual transition from aerobic to anaerobic lifestyles. The C/N showed marginally significant correlations with arsenic resistance (p?=?0.069) and carbon cycling genes (p?=?0.073), and significant correlation with nitrogen fixation genes (p?=?0.024). The combination of C/N, NO3? and P showed the highest correlation (r?=?0.779, p?=?0.062) with the microbial community structure. Contradict to our hypotheses, a long-term arsenic downward infiltration was not the primary factor, while the spatial isolation and nutrient availability were the key forces in shaping the community structure. This study provides new insights about the heterogeneity of microbial community metabolic potential and future biodiversity preservation for arsenic bioremediation management. PMID:23226297

  7. Soil microbial community responses to antibiotic-contaminated manure under different soil moisture regimes.

    PubMed

    Reichel, Rüdiger; Radl, Viviane; Rosendahl, Ingrid; Albert, Andreas; Amelung, Wulf; Schloter, Michael; Thiele-Bruhn, Sören

    2014-01-01

    Sulfadiazine (SDZ) is an antibiotic frequently administered to livestock, and it alters microbial communities when entering soils with animal manure, but understanding the interactions of these effects to the prevailing climatic regime has eluded researchers. A climatic factor that strongly controls microbial activity is soil moisture. Here, we hypothesized that the effects of SDZ on soil microbial communities will be modulated depending on the soil moisture conditions. To test this hypothesis, we performed a 49-day fully controlled climate chamber pot experiments with soil grown with Dactylis glomerata (L.). Manure-amended pots without or with SDZ contamination were incubated under a dynamic moisture regime (DMR) with repeated drying and rewetting changes of >20 % maximum water holding capacity (WHCmax) in comparison to a control moisture regime (CMR) at an average soil moisture of 38 % WHCmax. We then monitored changes in SDZ concentration as well as in the phenotypic phospholipid fatty acid and genotypic 16S rRNA gene fragment patterns of the microbial community after 7, 20, 27, 34, and 49 days of incubation. The results showed that strongly changing water supply made SDZ accessible to mild extraction in the short term. As a result, and despite rather small SDZ effects on community structures, the PLFA-derived microbial biomass was suppressed in the SDZ-contaminated DMR soils relative to the CMR ones, indicating that dynamic moisture changes accelerate the susceptibility of the soil microbial community to antibiotics. PMID:24743980

  8. Mangrove microbial diversity and the impact of trophic contamination.

    PubMed

    Bouchez, Agnès; Pascault, Noémie; Chardon, Cècile; Bouvy, Marc; Cecchi, Philippe; Lambs, Luc; Herteman, Mélanie; Fromard, François; Got, Patrice; Leboulanger, Christophe

    2013-01-15

    Mangroves are threatened ecosystems that provide numerous ecosystem services, especially through their wide biodiversity, and their bioremediation capacity is a challenging question in tropical areas. In a mangrove in Mayotte, we studied the potential role of microbial biofilm communities in removing nutrient loads from pre-treated wastewater. Microbial community samples were collected from tree roots, sediments, water, and from a colonization device, and their structure and dynamics were compared in two areas: one exposed to sewage and the other not. The samples from the colonization devices accurately reflected the natural communities in terms of diversity. Communities in the zone exposed to sewage were characterized by more green algae and diatoms, higher bacteria densities, as well as different compositions. In the area exposed to sewage, the higher cell densities associated with specific diversity patterns highlighted adapted communities that may play a significant role in the fate of nutrients. PMID:23218774

  9. Microbial Biofilm Formation and Contamination of Dental-Unit Water Systems in General Dental Practice

    Microsoft Academic Search

    JAMES T. WALKER; DAVID J. BRADSHAW; ALLAN M. BENNETT; MARTIN R. FULFORD; MICHAEL V. MARTIN; PHILIP D. MARSH

    2000-01-01

    Dental-unit water systems (DUWS) harbor bacterial biofilms, which may serve as a haven for pathogens. The aim of this study was to investigate the microbial load of water from DUWS in general dental practices and the biofouling of DUWS tubing. Water and tube samples were taken from 55 dental surgeries in southwestern England. Contamination was determined by viable counts on

  10. BIOGEOCHEMICAL EVIDENCE FOR MICROBIAL COMMUNITY CHANGE IN A JET FUEL HYDROCARBONS-CONTAMINATED AQUIFER

    EPA Science Inventory

    A glacio-fluvial aquifer located at Wurtsmith Air Force Base, Michigan, had been contaminated with JP-4 fuel hydrocarbons released after the crash of a tanker aircraft in October of 1988 Microbial biomass and community structure, associated with the aquifer sediments, were chara...

  11. Most modern wastewater treatment systems rely on microbial processes to remove contaminants. This makes wastewater

    E-print Network

    Auckland, University of

    Most modern wastewater treatment systems rely on microbial processes to remove contaminants. This makes wastewater treatment one of the largest biotechnology industries in the world. In New Zealand alone, about 1.5 billion litres of treated domestic wastewater is discharged each day

  12. Microbial hydroxylation of quinoline in contaminated groundwater: evidence for incorporation of the oxygen atom of water.

    PubMed Central

    Pereira, W E; Rostad, C E; Leiker, T J; Updegraff, D M; Bennett, J L

    1988-01-01

    Studies conducted in an aquifer contaminated by creosote suggest that quinoline is converted to 2(1H)quinolinone by an indigenous consortium of microorganisms. Laboratory microbial experiments using H218O indicate that water is the source of the oxygen atom for this hydroxylation reaction under aerobic and anaerobic conditions. PMID:3377494

  13. Microbial hydroxylation of quinoline in contaminated groundwater: evidence for incorporation of the oxygen atom of water.

    USGS Publications Warehouse

    Pereira, W.E.; Rostad, C.E.; Leiker, T.J.; Updegraff, D.M.; Bennett, J.L.

    1988-01-01

    Studies conducted in an aquifer contaminated by creosote suggest that quinoline is converted to 2(1H)quinolinone by an indigenous consortium of microorganisms. Laboratory microbial experiments using H218O indicate that water is the source of the oxygen atom for this hydroxylation reaction under aerobic and anaerobic conditions.

  14. Improvement of Drinking Water Quality in Developing Countries: Microbial and Geogenic Contamination

    E-print Network

    Wehrli, Bernhard

    Improvement of Drinking Water Quality in Developing Countries: Microbial and Geogenic Contamination for chemical and micro- biological treatment of drinking water at the household scale. The course will cover in developing and emerging coun- tries, who wish to learn more about household drinking water quality

  15. Enhancing microbial iron reduction in hyperalkaline, chromium contaminated sediments by pH amendment

    E-print Network

    Burke, Ian

    Enhancing microbial iron reduction in hyperalkaline, chromium contaminated sediments by p.2). Chromium was found to have accumulated in this soil as a result of an abiotic reaction of Cr(VI) with Fe; Deakin et al., 2001; Stewart et al., 2010). Chromium is extracted from its ore, chromite, by roasting

  16. IN SITU APPARENT CONDUCTIVITY MEASUREMENTS AND MICROBIAL POPULATION DISTRIBUTION AT A HYDROCARBON CONTAMINATED SITE

    EPA Science Inventory

    We investigated the bulk electrical conductivity and microbial population distribution in sediments at a site contaminated with light non-aqueous phase liquid (LNAPL). The bulk conductivity was measured using in situ vertical resistivity probes, while the most probable number met...

  17. MOLECULAR ANALYSIS OF MICROBIAL COMMUNITY STRUCTURES IN PRISTINE AND CONTAMINATED AQUIFERS: FIELD AND LABORATORY MICROCOSM EXPERIMENTS

    EPA Science Inventory

    This study used phylogenetic probes in hybridization analysis to (i) determine in situ microbial community structures in regions of a shallow sand aquifer that were oxygen depleted and fuel contaminated (FC) or aerobic and noncontaminted (NC) and (ii) examine alterations in micro...

  18. Flood management: prediction of microbial contamination in large-scale floods in urban environments.

    PubMed

    Taylor, Jonathon; Lai, Ka Man; Davies, Mike; Clifton, David; Ridley, Ian; Biddulph, Phillip

    2011-07-01

    With a changing climate and increased urbanisation, the occurrence and the impact of flooding is expected to increase significantly. Floods can bring pathogens into homes and cause lingering damp and microbial growth in buildings, with the level of growth and persistence dependent on the volume and chemical and biological content of the flood water, the properties of the contaminating microbes, and the surrounding environmental conditions, including the restoration time and methods, the heat and moisture transport properties of the envelope design, and the ability of the construction material to sustain the microbial growth. The public health risk will depend on the interaction of these complex processes and the vulnerability and susceptibility of occupants in the affected areas. After the 2007 floods in the UK, the Pitt review noted that there is lack of relevant scientific evidence and consistency with regard to the management and treatment of flooded homes, which not only put the local population at risk but also caused unnecessary delays in the restoration effort. Understanding the drying behaviour of flooded buildings in the UK building stock under different scenarios, and the ability of microbial contaminants to grow, persist, and produce toxins within these buildings can help inform recovery efforts. To contribute to future flood management, this paper proposes the use of building simulations and biological models to predict the risk of microbial contamination in typical UK buildings. We review the state of the art with regard to biological contamination following flooding, relevant building simulation, simulation-linked microbial modelling, and current practical considerations in flood remediation. Using the city of London as an example, a methodology is proposed that uses GIS as a platform to integrate drying models and microbial risk models with the local building stock and flood models. The integrated tool will help local governments, health authorities, insurance companies and residents to better understand, prepare for and manage a large-scale flood in urban environments. PMID:21481472

  19. Antibiotic, pesticide, and microbial contaminants of honey: human health hazards.

    PubMed

    Al-Waili, Noori; Salom, Khelod; Al-Ghamdi, Ahmed; Ansari, Mohammad Javed

    2012-01-01

    Agricultural contamination with pesticides and antibiotics is a challenging problem that needs to be fully addressed. Bee products, such as honey, are widely consumed as food and medicine and their contamination may carry serious health hazards. Honey and other bee products are polluted by pesticides, heavy metals, bacteria and radioactive materials. Pesticide residues cause genetic mutations and cellular degradation and presence of antibiotics might increase resistant human or animal's pathogens. Many cases of infant botulisms have been attributed to contaminated honey. Honey may be very toxic when produced from certain plants. Ingestion of honey without knowing its source and safety might be problematic. Honey should be labeled to explore its origin, composition, and clear statement that it is free from contaminants. Honey that is not subjected for analysis and sterilization should not be used in infants, and should not be applied to wounds or used for medicinal purposes. This article reviews the extent and health impact of honey contamination and stresses on the introduction of a strict monitoring system and validation of acceptable minimal concentrations of pollutants or identifying maximum residue limits for bee products, in particular, honey. PMID:23097637

  20. Antibiotic, Pesticide, and Microbial Contaminants of Honey: Human Health Hazards

    PubMed Central

    Al-Waili, Noori; Salom, Khelod; Al-Ghamdi, Ahmed; Ansari, Mohammad Javed

    2012-01-01

    Agricultural contamination with pesticides and antibiotics is a challenging problem that needs to be fully addressed. Bee products, such as honey, are widely consumed as food and medicine and their contamination may carry serious health hazards. Honey and other bee products are polluted by pesticides, heavy metals, bacteria and radioactive materials. Pesticide residues cause genetic mutations and cellular degradation and presence of antibiotics might increase resistant human or animal's pathogens. Many cases of infant botulisms have been attributed to contaminated honey. Honey may be very toxic when produced from certain plants. Ingestion of honey without knowing its source and safety might be problematic. Honey should be labeled to explore its origin, composition, and clear statement that it is free from contaminants. Honey that is not subjected for analysis and sterilization should not be used in infants, and should not be applied to wounds or used for medicinal purposes. This article reviews the extent and health impact of honey contamination and stresses on the introduction of a strict monitoring system and validation of acceptable minimal concentrations of pollutants or identifying maximum residue limits for bee products, in particular, honey. PMID:23097637

  1. Measurement of Microbially Induced Transformation of Magnetic Iron Minerals in Soils Allows Localization of Hydrocarbon Contamination

    NASA Astrophysics Data System (ADS)

    Kappler, A.; Porsch, K.; Rijal, M.; Appel, E.

    2007-12-01

    Soil contamination by crude oil and other hydrocarbons represents a severe environmental problem, but often the location and extent of contamination is not known. Hydrocarbons, or their degradation products, can stimulate iron-metabolizing microorganisms, leading to the formation or dissolution of (magnetic) iron minerals and an associated change of soil magnetic properties. Therefore, the screening of soil magnetic properties has the potential to serve as an efficient and inexpensive tool to localize such contaminations. In order to identify the influence of different biogeochemical factors on the microbially influenced changes of magnetic iron minerals after hydrocarbon contamination, oil spills were simulated in laboratory batch experiments. The parameters tested in these experiments included soils with different bedrocks, type and amount of added hydrocarbon, and microbiological parameters (sterile and autochthonous microorganisms). In order to follow the changes of the soil magnetic properties, the magnetic susceptibility of the samples was measured weekly. First results show that changes in the magnetic mineralogy are caused by microbial activity, as sterile samples showed no changes. In the microbially active set-ups, the magnetic susceptibility increased or decreased up to 10% in comparison to the initial magnetic susceptibility within a few weeks. In one iron-rich soil even a decrease of the magnetic susceptibility of ~40% was observed. Although the amount and type of hydrocarbons did not effect the changes in magnetic susceptibility, DGGE fingerprints revealed that they influenced microbial communities. These results show that the magnetic susceptibility changes in the presence of hydrocarbons and that this change is microbially induced. This suggests that the screening of soil magnetic properties can be applied to localize and assess hydrocarbon contamination. In order to understand the biogeochemical processes better, the change of the iron mineralogy will be followed by Moessbauer spectroscopy in future batch experiments. Furthermore, iron-metabolizing microorganisms are currently isolated and identified.

  2. [Microbial contamination of the air in the commercial production of poultry meat].

    PubMed

    Ba?kov, B D; Petkov, G

    1987-01-01

    Microbiologic studies were carried out on industrial premises for the raising of broiler birds on deep litter over a flooring area of 2000 m2 at mechanical ventilation of negative pressure. The microbial count was established through culturing in meat-and-peptone agar regarding the presence of coli bacteria, microscopic fungi, hemolytic cocci and Salmonellae in the air. Studies were also performed to establish the contamination of the atmospheric air at a distance of 10 m surrounding the premises, of the litter as well as of the feed and the soil in immediate proximity to the buildings. It was found that as a result of raising the 'biologic loading' of the ecotope by 60 per cent the microbial contamination of the air in the industrial buildings rose. The basic sources of contamination were the deep litter, the atmospheric air introduced by the ventilation system, the soil, and the feed. PMID:3617470

  3. Studies on possible propagation of microbial contamination in planetary clouds

    NASA Technical Reports Server (NTRS)

    Dimmick, R. L.; Chatigny, M. A.; Wolochow, H.

    1973-01-01

    One of the key parameters in estimation of the probability of contamintion of the outer planets (Jupiter, Saturn, Uranus, etc.) is the probability of growth (Pg) of terrestrial microorganisms on or near these planets. For example, Jupiter appears to have an atmosphere in which some microbial species could metabolize and propagate. This study includes investigation of the likelihood of metabolism and propagation of microbes suspended in dynamic atmospheres. It is directed toward providing experimental information needed to aid in rational estimation of Pg for these outer planets. Current work is directed at demonstration of aerial metabolism under near optimal conditions and tests of propagation in simulated Jovian atmospheres.

  4. Parenterals Laboratory Course to Reduce Microbial Contamination Rates in Media Fill Tests Performed by Pharmacy Students

    PubMed Central

    Isanhart, Christine M.; Kretschmer, Diane; Grimes, Barbie A.

    2008-01-01

    Objectives To evaluate microbial contamination rates of low- and medium-risk level media fill tests performed by pharmacy students near the beginning and end of a parenterals laboratory course in the second- professional year of a doctor of pharmacy (PharmD) program. Methods Students enrolled in a required parenterals laboratory class (N = 84) participated in this study. The aseptic technique procedures performed at the beginning of the course were identical to the procedures performed at the end of the course and included 3 low-risk level media-fill tests and a medium-risk level media-fill test. Single-strength trypticase-soy broth (TSB) was substituted for the drug and was used to detect microbial contamination for all manipulations. Results The baseline and end-of-course contamination rate was 21 of 504 syringes and 0 of 498 syringes, respectively (p < 0.001). Eighteen of 84 students at baseline and 0 of 83 students near the end of the course produced one or more contaminated syringes (p < 0.001). Of the 21 contaminated syringes at baseline, low-risk manipulations accounted for 14 and medium-risk manipulations accounted for 7. Of the low-risk procedures, the ampule produced the highest contamination rate (11 syringes), followed by the vial (2 syringes) and the reconstitution (1 syringe). Conclusions This study demonstrated a decreased rate of microbial contamination during the manipulation of parenteral products and a corresponding improvement in aseptic technique skills among pharmacy students enrolled in a parenterals laboratory course. The most sensitive tests for poor aseptic technique and bacterial contamination were medium-risk manipulations and low-risk manipulations involving an ampule. PMID:18483595

  5. Portable spotter for fluorescent contaminants on surfaces

    DOEpatents

    Schuresko, Daniel D. (Oak Ridge, TN)

    1980-01-01

    A portable fluorescence-based spotter for polynuclear aromatic hydrocarbon contamination on personnel and work area surfaces under ambient lighting conditions is provided. This instrument employs beam modulation and phase sensitive detection for discriminating between fluorescence from organic materials from reflected background light and inorganic fluorescent material. The device uses excitation and emission filters to provide differentiation between classes of aromatic organic compounds. Certain inorganic fluorescent materials, including heavy metal compounds, may also be distinguished from the organic compounds, despite both having similar optical properties.

  6. Early warning system for detection of microbial contamination of source waters

    NASA Astrophysics Data System (ADS)

    Mogensen, Claus Tilsted; Bentien, Anders; Lau, Mogens; Højris, Bo; Iversen, Kåre; Klinting, Mette; Berg, Tommy Winter; Agersnap, Niels; Valvik, Martin

    2011-06-01

    Ensuring chemical and microbial water quality is an ever increasing important issue world-wide. Currently, determination of microbial water quality is a time (and money) consuming manual laboratory process. We have developed and field-tested an online and real-time sensor for measuring the microbial water quality of a wide range of source waters. The novel optical technique, in combination with advanced data analysis, yields a measure for the microbial content present in the sample. This gives a fast and reliable detection capability of microbial contamination of the source. Sample acquisition and analysis is performed real-time where objects in suspension are differentiated into e.g. organic/inorganic subgroups. The detection system is a compact, low power, reagentless device and thus ideal for applications where long service intervals and remote operations are desired. Due to the very large dynamic range in measured parameters, the system is able to monitor process water in industry and food production as well as monitor waste water, source water and water distribution systems. The applications envisioned for this system includes early warning of source water contamination and/or variation. This includes: water plants/water distribution networks, filtration systems (water purification), commercial buildings, swimming pools, waste water effluent, and industry in general.

  7. Rhizosphere effect of Scirpus triqueter on soil microbial structure during phytoremediation of diesel-contaminated wetland.

    PubMed

    Wei, Jing; Liu, Xiaoyan; Zhang, Xinying; Chen, Xueping; Liu, Shanshan; Chen, Lisha

    2014-01-01

    Though phytoremediation has been widely used to restore various contaminated sites, it is still unclear how soil microbial communities respond microecologically to plants and pollutants during the process. In this paper, batch microcosms imitating in situ phytoremediation of petroleum-contaminated wetland by Scirpus triqueter were set up to monitor the influence of plant rhizosphere effect on soil microbes. Palmitic acid, one of the main root exudates of S. triqueter, was added to strengthen rhizosphere effect. Abundances of certain microbial subgroups were quantified by phospholipid fatty acid profiles. Results showed that diesel removal extents were significantly higher in the rhizosphere (57.6 +/-4.2-65.5 +/- 6.9%) than those in bulk soil (27.8 +/-6.5-36.3 +/- 3.2%). In addition, abundances of saturated, monounsaturated, and polyunsaturated fatty acids were significantly higher (P < 0.05) in planted soil than those in the bulk soil. When it was less than 15,000 mg diesel kg soil-1, increasing diesel concentration led to higher abundances of fungi, Gram-positive and Gram-negative bacteria. The addition of palmitic acid amplified the rhizosphere effect on soil microbial populations and diesel removal. Principal component analysis revealed that plant rhizosphere effect was the dominant factor affecting microbial structure. These results provided new insights into plant-microbe-pollutant coactions responsible for diesel degradation, and they were valuable to facilitate phytoremediation of diesel contamination in wetland habitats. PMID:24600892

  8. Comparison and relationship between functional changes of macroinvertebrates and microbial communities in response to resuspension of contaminated sediment

    E-print Network

    Paris-Sud XI, Université de

    communities in response to resuspension of contaminated sediment Fanny Colas1,*, Simon Devin1, & Virginie-mail:fanny.colas@umail.univ-metz.fr) Key words: sediment, metals contamination, resuspension, biomonitoring, macroinvertebrates, microbial contamination of sediments from surrounding industry and urbanization pose a serious ecological threat

  9. Changes in microbial community structure during long-term incubation in two soils experimentally contaminated with metals

    Microsoft Academic Search

    Å. Frostegård; A. Tunlid; E. Bååth

    1996-01-01

    The effects of Zn contamination on the microbial community structure of a forest humus and an arable soil, as estimated by phospholipid fatty acid (PLFA) analysis, were followed during 18 months. The soils were contaminated at 10 different metal concentrations and incubated in plastic jars at 22°C. In both soils effects of heavy metal contamination could be detected after 2

  10. Effect of contaminant concentration on aerobic microbial mineralization of DCE and VC in stream-bed sediments

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.

    1998-01-01

    Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater continuously discharges, demonstrated rapid mineralization of DCE and VC under aerobic conditions. Over 8 days, the recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 17% to 100%, and the recovery of [1,2- 14C]VC radioactivity as 14CO2 ranged from 45% to 100%. Rates of DCE and VC mineralization increased significantly with increasing contaminant concentration, and the response of apparent mineralization rates to changes in DCE and VC concentrations was adequately described by Michaelis-Menten kinetics.Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater continuously discharges, demonstrated rapid mineralization of DCE and VC under aerobic conditions. Over 8 days, the recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 17% to 100%, and the recovery of [1,2-14C]VC radioactivity as 14CO2 ranged from 45% to 100%. Rates of DCE and VC mineralization increased significantly with increasing contaminant concentration, and the response of apparent mineralization rates to changes in DCE and VC concentrations was adequately described by Michaelis-Menten kinetics.

  11. Functional gene array-based analysis of microbial communities in heavy metals-contaminated lake sediments.

    PubMed

    Kang, Sanghoon; Van Nostrand, Joy D; Gough, Heidi L; He, Zhili; Hazen, Terry C; Stahl, David A; Zhou, Jizhong

    2013-11-01

    Lake DePue (IL, USA) has been contaminated for > 80 years by an adjacent Zn-smelting facility. Previous work indicated that sulfate reduction increased and biomass declined as pore-water metal concentrations increased, while 16S rRNA gene profiles remained relatively stable. To better understand this phenomenon, the sediment microbial community structure and functional potential were investigated using a functional gene microarray (GeoChip) targeting > 10,000 functional genes. Nonmetric multidimensional scaling and clustering analyses showed that the overall community structure was similar across all sites based on the relative abundance of all detected genes, but some individual gene categories did show differences. A subset of sulfate reduction genes (dsr) and the most relevant metal resistance genes were more abundant than other categories and were highly correlated with metal contamination. The most significant correlations were between pore-water metal concentrations and dsr, with Zn, Cd, and Mn as the most predictive for the presence of dsr. These results suggest that metal contamination influences sediment microbial community structure and function by increasing the abundance of relevant metal-resistant and sulfate-reducing populations. These populations therefore appear to contribute significantly to the resistance and stability of the microbial communities throughout the gradient of metal contamination in Lake DePue. PMID:23710534

  12. Surface interactions relevant to space station contamination problems

    NASA Technical Reports Server (NTRS)

    Dickinson, J. T.

    1988-01-01

    The physical and chemical processes at solid surfaces which can contribute to Space Station contamination problems are reviewed. Suggested areas for experimental studies to provide data to improve contamination modeling efforts are presented.

  13. Microbial source tracking in a coastal California watershed reveals canines as controllable sources of fecal contamination.

    PubMed

    Ervin, Jared S; Van De Werfhorst, Laurie C; Murray, Jill L S; Holden, Patricia A

    2014-08-19

    Elevated levels of fecal indicator bacteria (FIB), including Escherichia coli and enterococci, trigger coastal beach advisories and signal public health risks. Solving FIB pollution in suburban coastal watersheds is challenging, as there are many potential sources. The Arroyo Burro watershed in Santa Barbara, CA is an example, with its popular, but chronically FIB-contaminated beach. To address, a microbial source tracking study was performed. Surface waters were sampled over 2 years, FIB were quantified, and DNA was analyzed for host-associated fecal markers. Surf zone FIB were only elevated when the coastal lagoon was discharging. Among the fecal sources into the lagoon, including upstream human sources and coastal birds, canines were the most important. Canine sources included input via upstream creek water, which decreased after creek-side residences were educated about proper pet waste disposal, and direct inputs to the lagoon and surf zone, where dog waste could have been tidally exchanged with the lagoon. Based on this study, canine waste can be an influential, yet controllable, fecal source to suburban coastal beaches. PMID:25055204

  14. Microbial cycling of mercury in contaminated pelagic and wetland sediments of San Pablo Bay, California

    USGS Publications Warehouse

    Marvin-DiPasquale, M. C.; Agee, J.L.; Bouse, R.M.; Jaffe, B.E.

    2003-01-01

    San Pablo Bay is an estuary, within northern San Francisco Bay, containing elevated sediment mercury (Hg) levels because of historic loading of hydraulic mining debris during the California gold-rush of the late 1800s. A preliminary investigation of benthic microbial Hg cycling was conducted in surface sediment (0-4 cm) collected from one salt-marsh and three open-water sites. A deeper profile (0-26 cm) was evaluated at one of the open-water locations. Radiolabeled model Hg-compounds were used to measure rates of both methylmercury (MeHg) production and degradation by bacteria. While all sites and depths had similar total-Hg concentrations (0.3-0.6 ppm), and geochemical signatures of mining debris (as eNd, range: -3.08 to -4.37), in-situ MeHg was highest in the marsh (5.4??3.5 ppb) and ??? 0.7 ppb in all open-water sites. Microbial MeHg production (potential rate) in 0-4 surface sediments was also highest in the marsh (3.1 ng g-1 wet sediment day-1) and below detection (<0.06 ng g-1 wet sediment day-1) in open-water locations. The marsh exhibited a methylation/demethylation (M/D) ratio more than 25x that of all open-water locations. Only below the surface 0-4-cm horizon was significant MeHg production potential evident in the open-water sediment profile (0.2-1.1 ng g-1 wet sediment day-1). In-situ Hg methylation rates, calculated from radiotracer rate constants, and in-situ inorganic Hg(II) concentrations compared well with potential rates. However, similarly calculated in-situ rates of MeHg degradation were much lower than potential rates. These preliminary data indicate that wetlands surrounding San Pablo Bay represent important zones of MeHg production, more so than similarly Hg-contaminated adjacent open-water areas. This has significant implications for this and other Hg-impacted systems, where wetland expansion is currently planned.

  15. Functional gene array-based analysis of microbial community structure in groundwaters with a gradient of contaminant levels

    SciTech Connect

    Waldron, P.J.; Wu, L.; Van Nostrand, J.D.; Schadt, C.W.; Watson, D.B.; Jardine, P.M.; Palumbo, A.V.; Hazen, T.C.; Zhou, J.

    2009-06-15

    To understand how contaminants affect microbial community diversity, heterogeneity, and functional structure, six groundwater monitoring wells from the Field Research Center of the U.S. Department of Energy Environmental Remediation Science Program (ERSP; Oak Ridge, TN), with a wide range of pH, nitrate, and heavy metal contamination were investigated. DNA from the groundwater community was analyzed with a functional gene array containing 2006 probes to detect genes involved in metal resistance, sulfate reduction, organic contaminant degradation, and carbon and nitrogen cycling. Microbial diversity decreased in relation to the contamination levels of the wells. Highly contaminated wells had lower gene diversity but greater signal intensity than the pristine well. The microbial composition was heterogeneous, with 17-70% overlap between different wells. Metal-resistant and metal-reducing microorganisms were detected in both contaminated and pristine wells, suggesting the potential for successful bioremediation of metal-contaminated groundwaters. In addition, results of Mantel tests and canonical correspondence analysis indicate that nitrate, sulfate, pH, uranium, and technetium have a significant (p < 0.05) effect on microbial community structure. This study provides an overall picture of microbial community structure in contaminated environments with functional gene arrays by showing that diversity and heterogeneity can vary greatly in relation to contamination.

  16. Microbial contamination of a disinfectant-soaked unwoven cleaning cloth.

    PubMed

    Oie, S; Arakawa, J; Furukawa, H; Matsumoto, S; Matsuda, N; Wakamatsu, H

    2012-09-01

    In December 2009, a 76-year-old male patient developed pneumonia due to Burkholderia cepacia whilst in an intensive care unit at a Japanese university hospital. During the subsequent environmental investigation to find the source, B. cepacia with an identical DNA type was found in his denture storage solution. Open packets of unwoven rayon cloths soaked in 0.2% alkyldiaminoethylglycine hydrochloride, used for environmental cleaning, were shown to be contaminated with B. cepacia, Alcaligenes xylosoxidans, Pseudomonas fluorescens and Pseudomonas aeruginosa. B. cepacia of a different DNA type was found in five of 42 samples from sealed packets of cloths. PMID:22854353

  17. Contamination of shallow wells in Nigeria from surface contaminant migration

    SciTech Connect

    Ademoroti, C.M.A. (Univ. of Benin (Nigeria))

    1987-01-01

    Contaminated wells, located in six south/western and western states of Nigeria, were sampled and analyzed for pollution characteristics. Results of analysis indicated migration of contaminants into the wells from places where there was a potential source. There was a significant microbiological population in the wells placed near domestic waste sites. Also, there were excessive levels of trace heavy metals in those placed near metal dumping sites. On the other hand, the contaminants were minimal in wells that were not close to polluting sources. The studies revealed that groundwater contamination occurred primarily by dumping of wastes, wrong placement of waste disposal facilities, and improper construction of wells. The groundwater sources (wells, etc.) are used when pipe-borne water facilities are inadequate.

  18. Microbial contamination of ambient air by ultrasonic humidifier and preventive measures.

    PubMed

    Oie, S; Masumoto, N; Hironaga, K; Koshiro, A; Kamiya, A

    1992-01-01

    The microbially contaminated ultrasonic humidifier (UH) causes humidifier fever. The number of airborne viable bacteria was determined when the UH was operating, and other methods to humidify the air of hospital wards were also examined. A UH contaminated with 10(5) bacteria ml(-1), a level common in hospitals, increased the bacterial count in the air from 860 m(-3) to 88,000 m(-3) at a distance of 3 m from the humidifier. Thus UH in hospitals may contaminate the air and be a potential hazard to patients. Contamination was slight when a washable and disinfectable ultrasonic nebulizer was used with disinfection at 24 h intervals. In tracheostomy patients requiring a high degree of air humidification, ultrasonic nebulizers which are readily washed and disinfected are recommended. PMID:1488018

  19. Microbially supported phytoremediation of heavy metal contaminated soils: strategies and applications.

    PubMed

    Phieler, René; Voit, Annekatrin; Kothe, Erika

    2014-01-01

    Heavy metal contamination of soil as a result of, for example, mining operations, evokes worldwide concern. The use of selected metal-accumulating plants to clean up heavy metal contaminated sites represents a sustainable and inexpensive method for remediation approaches and, at the same time, avoids destruction of soil function. Within this scenario, phytoremediation is the use of plants (directly or indirectly) to reduce the risks of contaminants in soil to the environment and human health. Microbially assisted bioremediation strategies, such as phytoextraction or phytostabilization, may increase the beneficial aspects and can be viewed as potentially useful methods for application in remediation of low and heterogeneously contaminated soil. The plant-microbe interactions in phytoremediation strategies include mutually beneficial symbiotic associations such as mycorrhiza, plant growth promoting bacteria (PGPB), or endophytic bacteria that are discussed with respect to their impact on phytoremediation approaches. PMID:23719709

  20. Factors affecting microbial 2,4,6-trinitrotoluene mineralization in contaminated soil

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.

    1995-01-01

    The influence of selected environmental factors on microbial TNT mineralization in soils collected from a TNT-contaminated site at Weldon Spring, MO, was examined using uniformly ring-labeled [14C]TNT. Microbial TNT mineralization was significantly inhibited by the addition of cellobiose and syringate. This response suggests that the indigenous microorganisms are capable of metabolizing TNT but preferentially utilize less recalcitrant substrates when available. The observed inhibition of TNT mineralization by TNT concentrations higher than 100 ??mol/kg of soil and by dry soil conditions suggests that toxic inhibition of microbial activity at high TNT concentrations and the periodic drying of these soils have contributed to the long-term persistence of TNT at Weldon Spring. In comparison to aerobic microcosms, mineralization was inhibited in anaerobic microcosms and in microcosms with a headspace of air amended with oxygen, suggesting that a mosaic of aerobic and anaerobic conditions may optimize TNT degradation at this site.

  1. Tracking microbial contamination in retail environments using fluorescent powder--a retail delicatessen environment example.

    PubMed

    Sirsat, Sujata A; Kim, Kawon; Gibson, Kristen E; Crandall, Phillip G; Ricke, Steven C; Neal, Jack A

    2014-01-01

    Cross contamination of foodborne pathogens in the retail environment is a significant public health issue contributing to an increased risk for foodborne illness. Ready-to-eat (RTE) processed foods such as deli meats, cheese, and in some cases fresh produce, have been involved in foodborne disease outbreaks due to contamination with pathogens such as Listeria monocytogenes. With respect to L. monocytogenes, deli slicers are often the main source of cross contamination. The goal of this study was to use a fluorescent compound to simulate bacterial contamination and track this contamination in a retail setting. A mock deli kitchen was designed to simulate the retail environment. Deli meat was inoculated with the fluorescent compound and volunteers were recruited to complete a set of tasks similar to those expected of a food retail employee. The volunteers were instructed to slice, package, and store the meat in a deli refrigerator. The potential cross contamination was tracked in the mock retail environment by swabbing specific areas and measuring the optical density of the swabbed area with a spectrophotometer. The results indicated that the refrigerator (i.e. deli case) grip and various areas on the slicer had the highest risk for cross contamination. The results of this study may be used to develop more focused training material for retail employees. In addition, similar methodologies could also be used to track microbial contamination in food production environments (e.g. small farms), hospitals, nursing homes, cruise ships, and hotels. PMID:24637553

  2. Enhanced detection of groundwater contamination from a leaking waste disposal site by microbial community profiles

    NASA Astrophysics Data System (ADS)

    Mouser, Paula J.; Rizzo, Donna M.; Druschel, Gregory K.; Morales, Sergio E.; Hayden, Nancy; O'Grady, Patrick; Stevens, Lori

    2010-12-01

    Groundwater biogeochemistry is adversely impacted when municipal solid waste leachate, rich in nutrients and anthropogenic compounds, percolates into the subsurface from leaking landfills. Detecting leachate contamination using statistical techniques is challenging because well strategies or analytical techniques may be insufficient for detecting low levels of groundwater contamination. We sampled profiles of the microbial community from monitoring wells surrounding a leaking landfill using terminal restriction fragment length polymorphism (T-RFLP) targeting the 16S rRNA gene. Results show in situ monitoring of bacteria, archaea, and the family Geobacteraceae improves characterization of groundwater quality. Bacterial T-RFLP profiles showed shifts correlated to known gradients of leachate and effectively detected changes along plume fringes that were not detected using hydrochemical data. Experimental sediment microcosms exposed to leachate-contaminated groundwater revealed a shift from a ?-Proteobacteria and Actinobacteria dominated community to one dominated by Firmicutes and ?-Proteobacteria. This shift is consistent with the transition from oxic conditions to an anoxic, iron-reducing environment as a result of landfill leachate-derived contaminants and associated redox conditions. We suggest microbial communities are more sensitive than hydrochemistry data for characterizing low levels of groundwater contamination and thus provide a novel source of information for optimizing detection and long-term monitoring strategies at landfill sites.

  3. Development of a microbial contamination susceptibility model for private domestic groundwater sources

    NASA Astrophysics Data System (ADS)

    Hynds, Paul D.; Misstear, Bruce D.; Gill, Laurence W.

    2012-12-01

    Groundwater quality analyses were carried out on samples from 262 private sources in the Republic of Ireland during the period from April 2008 to November 2010, with microbial quality assessed by thermotolerant coliform (TTC) presence. Assessment of potential microbial contamination risk factors was undertaken at all sources, and local meteorological data were also acquired. Overall, 28.9% of wells tested positive for TTC, with risk analysis indicating that source type (i.e., borehole or hand-dug well), local bedrock type, local subsoil type, groundwater vulnerability, septic tank setback distance, and 48 h antecedent precipitation were all significantly associated with TTC presence (p < 0.05). A number of source-specific design parameters were also significantly associated with bacterial presence. Hierarchical logistic regression with stepwise parameter entry was used to develop a private well susceptibility model, with the final model exhibiting a mean predictive accuracy of >80% (TTC present or absent) when compared to an independent validation data set. Model hierarchies of primary significance are source design (20%), septic tank location (11%), hydrogeological setting (10%), and antecedent 120 h precipitation (2%). Sensitivity analysis shows that the probability of contamination is highly sensitive to septic tank setback distance, with probability increasing linearly with decreases in setback distance. Likewise, contamination probability was shown to increase with increasing antecedent precipitation. Results show that while groundwater vulnerability category is a useful indicator of aquifer susceptibility to contamination, its suitability with regard to source contamination is less clear. The final model illustrates that both localized (well-specific) and generalized (aquifer-specific) contamination mechanisms are involved in contamination events, with localized bypass mechanisms dominant. The susceptibility model developed here could be employed in the appropriate location, design, construction, and operation of private groundwater wells, thereby decreasing the contamination risk, and hence health risk, associated with these sources.

  4. QUANTITATIVE CHARACTERIZATION OF MICROBIAL BIOMASS AND COMMUNITY STRUCTURE IN SUBSURFACE MATERIAL: A PROKARYOTIC CONSORTIUM RESPONSIVE TO ORGANIC CONTAMINATION

    EPA Science Inventory

    Application of quantitative methods for microbial biomass, community structure, and nutritional status to the subsurface samples collected with careful attention to contamination reveals a group of microbes. The microbiota are sparse by several measures of biomass compared to sur...

  5. Microbial Community Succession During Lactate Amendment of Chromium Contaminated Groundwater Reveals a Predominance of Pelosinus spp.

    SciTech Connect

    Mosher, Jennifer J [ORNL; Phelps, Tommy Joe [ORNL; Drake, Meghan M [ORNL; Campbell, James H [ORNL; Moberly, James G [ORNL; Schadt, Christopher Warren [ORNL; Podar, Mircea [ORNL; Brown, Steven D [ORNL; Hazen, Terry [Lawrence Berkeley National Laboratory (LBNL); Arkin, Adam [Lawrence Berkeley National Laboratory (LBNL); Palumbo, Anthony Vito [ORNL; Faybishenko, Boris A [Lawrence Berkeley National Laboratory (LBNL); Elias, Dwayne A [ORNL

    2012-01-01

    Microbial community structure and metabolism in contaminated ecosystems are potentially controlled not only by the different populations within the community, but a myriad of dynamic physicochemical parameters as well. The goal of the current work was to determine the impact of organic acid enrichment, in this case lactate, on the succession of the native microbial community from a contaminated groundwater aquifer. Triplicate anaerobic, continuous-flow glass reactors were inoculated with Hanford 100-H groundwater and incubated for 95 days to obtain a stable, enriched community. The microbial community experienced a shift in the population dynamics over time to eventually form a community with far less diversity than the original. The final community was dominated by Pelosinus spp. and to a lesser degree, Acetobacterium spp. with small amounts of other bacteria and archaea including methanogens. The resultant diversity was far decreased from 63 genera within 12 phyla to 11 bacterial genera (from three phyla) and 2 archaeal genera (from one phylum). Isolation efforts were successful in attaining new species of Pelosinus and known members of Methanosarcina barkerii along with several sulfate- and Fe(III)- reducing consortia members. The continuous-flow reactors allowed for testing physiochemical factors with microbial community dynamics on a smaller, replicable, scale while also facilitating the isolation of several previously uncultured community members. These lab-scale simulations will presumably allow for a deeper understanding of the community metabolism with specific carbon amendments that can inform future in situ efforts.

  6. Microbial contamination of preservative free eye drops in multiple application containers

    PubMed Central

    Rahman, M Q; Tejwani, D; Wilson, J A; Butcher, I; Ramaesh, K

    2006-01-01

    Background/aims The majority of eye drops used in the United Kingdom contain preservatives and are bottled in plastic containers. Preservative free drops are used to avoid ocular irritation and allergies in certain individuals. The aim of this study was to investigate the incidence of microbial contamination of preservative free drops dispensed from multiusage containers. Methods Eye drop bottles were collected from patients attending the Tennent Institute of Ophthalmology outpatient and inpatient departments. The bottles were collected on day 3 (for inpatients) and day 7 (for outpatients) of use. The drops were inoculated onto different culture plates (chocolate agar, blood agar, fungal culture media, and enriched media) and the resulting microbial growth was identified using standard microbial identification techniques. Results 95 eye drop bottles were collected, containing a variety of 10 different eye drops. Significant bacterial growth was found in eight bottles. In total, seven different types of organism were identified from the eye drops. The organisms identified were Staphylococcus aureus, coagulase negative staphylococcus, Bacillus spp, Serattia spp, Klebsiella oxytoca, Enterobacter cloacae, and alpha streptococcus. Staph aureus was the commonest microbial organism. Conclusion Preservative free eye drops in multiple application containers are at risk of contamination by potentially pathogenic micro?organisms. PMID:16424520

  7. Microbial Communities Associated with Anaerobic Benzene Degradation in a Petroleum-Contaminated Aquifer

    Microsoft Academic Search

    JULIETTE N. ROONEY-VARGA; ROBERT T. ANDERSON; JOCELYN L. FRAGA; DEREK R. LOVLEY

    1999-01-01

    Microbial community composition associated with benzene oxidation under in situ Fe(III)-reducing condi- tions in a petroleum-contaminated aquifer located in Bemidji, Minn., was investigated. Community structure associated with benzene degradation was compared to sediment communities that did not anaerobically oxidize benzene which were obtained from two adjacent Fe(III)-reducing sites and from methanogenic and uncon- taminated zones. Denaturing gradient gel electrophoresis of

  8. Dissemination of microbial contaminants from house flies electrocuted by five insect light traps

    Microsoft Academic Search

    Michael J. Tesch; Walter G. Goodman

    1995-01-01

    Five insect light traps were tested for their ability to produce microbial contamination by house fly electrocution. Four traps use high voltage to kill or maim flies: Gardner®, model AG61; Fly Magnet®, Ecolab model 1890; Don Gilbert® Industries, Model 220; and Insect?O?Cutor®, model 2489DGA Sentinel. The fifth trap, Micro Gen Vector® system, model 2000, disorients flies with a low voltage,

  9. Relating ground water and sediment chemistry to microbial characterization at a BTEX-contaminated site

    Microsoft Academic Search

    S. M. Pfiffner; A. V. Palumbo; T. Gibson; D. B. Ringelberg; J. F. McCarthy

    1997-01-01

    The National Center for Manufacturing Science is investigating bioremediation of petroleum hydrocarbon at a site near Belleville,\\u000a MI. As part of this study, we examined the microbial communities to help elucidate biodegradative processes currently active\\u000a at the site. We observed high densities of aerobic hydrocarbon degraders and denitrifiers in the less-contaminated sediments.\\u000a Low densities of iron and sulfate reducers were

  10. Microbial Contamination in Next Generation Sequencing: Implications for Sequence-Based Analysis of Clinical Samples

    PubMed Central

    Strong, Michael J.; Xu, Guorong; Morici, Lisa; Splinter Bon-Durant, Sandra; Baddoo, Melody; Lin, Zhen; Fewell, Claire; Taylor, Christopher M.; Flemington, Erik K.

    2014-01-01

    The high level of accuracy and sensitivity of next generation sequencing for quantifying genetic material across organismal boundaries gives it tremendous potential for pathogen discovery and diagnosis in human disease. Despite this promise, substantial bacterial contamination is routinely found in existing human-derived RNA-seq datasets that likely arises from environmental sources. This raises the need for stringent sequencing and analysis protocols for studies investigating sequence-based microbial signatures in clinical samples. PMID:25412476

  11. Microbial diversity in a hydrocarbon- and chlorinated-solvent-contaminated aquifer undergoing intrinsic bioremediation

    Microsoft Academic Search

    MICHAEL A. DOJKA; PHILIP HUGENHOLTZ; N. R. Pace; S. K. Haack

    1998-01-01

    A culture-independent molecular phylogenetic approach was used to survey constituents of microbial communities associated with an aquifer contaminated with hydrocarbons and chlorinated solvents undergoing intrinsic bioremediation. Samples were obtained from three redox zones: methanogenic, methanogenic-sulfate reducing, and iron or sulfate reducing. Small-subunit rRNA genes were amplified directly from aquifer material DNA by PCR with universally conserved or Bacteria- or Archaea-specific

  12. Interactions of Hyperthermal Gas Particles with Contaminated Surfaces

    Microsoft Academic Search

    K. C. Chiang; E. L. Knuth

    1970-01-01

    Interactions of hyperthermal molecules with contaminated surfaces are studied analytically for a simple classical model in which the surface is covered by a monolayer of physisorbed contaminant and the gas particle energy is much greater than that corresponding to the temperature of the solid. Calculations indicate that if the adsorption potential varies periodically along the surface, then the adsorbed particles

  13. Microbial abundance in surface ice on the Greenland Ice Sheet

    PubMed Central

    Stibal, Marek; Gözdereliler, Erkin; Cameron, Karen A.; Box, Jason E.; Stevens, Ian T.; Gokul, Jarishma K.; Schostag, Morten; Zarsky, Jakub D.; Edwards, Arwyn; Irvine-Fynn, Tristram D. L.; Jacobsen, Carsten S.

    2015-01-01

    Measuring microbial abundance in glacier ice and identifying its controls is essential for a better understanding and quantification of biogeochemical processes in glacial ecosystems. However, cell enumeration of glacier ice samples is challenging due to typically low cell numbers and the presence of interfering mineral particles. We quantified for the first time the abundance of microbial cells in surface ice from geographically distinct sites on the Greenland Ice Sheet (GrIS), using three enumeration methods: epifluorescence microscopy (EFM), flow cytometry (FCM), and quantitative polymerase chain reaction (qPCR). In addition, we reviewed published data on microbial abundance in glacier ice and tested the three methods on artificial ice samples of realistic cell (102–107 cells ml?1) and mineral particle (0.1–100 mg ml?1) concentrations, simulating a range of glacial ice types, from clean subsurface ice to surface ice to sediment-laden basal ice. We then used multivariate statistical analysis to identify factors responsible for the variation in microbial abundance on the ice sheet. EFM gave the most accurate and reproducible results of the tested methodologies, and was therefore selected as the most suitable technique for cell enumeration of ice containing dust. Cell numbers in surface ice samples, determined by EFM, ranged from ~ 2 × 103 to ~ 2 × 106 cells ml?1 while dust concentrations ranged from 0.01 to 2 mg ml?1. The lowest abundances were found in ice sampled from the accumulation area of the ice sheet and in samples affected by fresh snow; these samples may be considered as a reference point of the cell abundance of precipitants that are deposited on the ice sheet surface. Dust content was the most significant variable to explain the variation in the abundance data, which suggests a direct association between deposited dust particles and cells and/or by their provision of limited nutrients to microbial communities on the GrIS. PMID:25852678

  14. Microbial abundance in surface ice on the Greenland Ice Sheet.

    PubMed

    Stibal, Marek; Gözdereliler, Erkin; Cameron, Karen A; Box, Jason E; Stevens, Ian T; Gokul, Jarishma K; Schostag, Morten; Zarsky, Jakub D; Edwards, Arwyn; Irvine-Fynn, Tristram D L; Jacobsen, Carsten S

    2015-01-01

    Measuring microbial abundance in glacier ice and identifying its controls is essential for a better understanding and quantification of biogeochemical processes in glacial ecosystems. However, cell enumeration of glacier ice samples is challenging due to typically low cell numbers and the presence of interfering mineral particles. We quantified for the first time the abundance of microbial cells in surface ice from geographically distinct sites on the Greenland Ice Sheet (GrIS), using three enumeration methods: epifluorescence microscopy (EFM), flow cytometry (FCM), and quantitative polymerase chain reaction (qPCR). In addition, we reviewed published data on microbial abundance in glacier ice and tested the three methods on artificial ice samples of realistic cell (10(2)-10(7) cells ml(-1)) and mineral particle (0.1-100 mg ml(-1)) concentrations, simulating a range of glacial ice types, from clean subsurface ice to surface ice to sediment-laden basal ice. We then used multivariate statistical analysis to identify factors responsible for the variation in microbial abundance on the ice sheet. EFM gave the most accurate and reproducible results of the tested methodologies, and was therefore selected as the most suitable technique for cell enumeration of ice containing dust. Cell numbers in surface ice samples, determined by EFM, ranged from ~ 2 × 10(3) to ~ 2 × 10(6) cells ml(-1) while dust concentrations ranged from 0.01 to 2 mg ml(-1). The lowest abundances were found in ice sampled from the accumulation area of the ice sheet and in samples affected by fresh snow; these samples may be considered as a reference point of the cell abundance of precipitants that are deposited on the ice sheet surface. Dust content was the most significant variable to explain the variation in the abundance data, which suggests a direct association between deposited dust particles and cells and/or by their provision of limited nutrients to microbial communities on the GrIS. PMID:25852678

  15. Assessment of the level of microbial contamination in cotton and synthetic fibers destined for the use in nonwoven applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microbial burden measurements are crucial for certain converter uses of nonwoven materials. Currently, the microbial burden of natural fibers such as cotton have not been quantified and little consideration has been given to the potential contamination introduced by synthetic fibers during the proc...

  16. Maple sap predominant microbial contaminants are correlated with the physicochemical and sensorial properties of maple syrup.

    PubMed

    Filteau, Marie; Lagacé, Luc; Lapointe, Gisèle; Roy, Denis

    2012-03-01

    Maple sap processing and microbial contamination are significant aspects that affect maple syrup quality. In this study, two sample sets from 2005 and 2008 were used to assess the maple syrup quality variation and its relationship to microbial populations, with respect to processing, production site and harvesting period. The abundance of maple sap predominant bacteria (Pseudomonas fluorescens group and two subgroups, Rahnella spp., Janthinobacterium spp., Leuconostoc mesenteroides) and yeast (Mrakia spp., Mrakiella spp.,Guehomyces pullulans) was assessed by quantitative PCR. Maple syrup properties were analyzed by physicochemical and sensorial methods. Results indicate that P. fluorescens, Mrakia spp., Mrakiella spp. G. pullulans and Rahnella spp. are stable contaminants of maple sap, as they were found for every production site throughout the flow period. Multiple factor analysis reports a link between the relative abundance of P. fluorescens group and Mrakia spp. in maple sap with maple and vanilla odor as well as flavor of maple syrup. This evidence supports the contribution of these microorganisms or a consortium of predominant microbial contaminants to the characteristic properties of maple syrup. PMID:22236761

  17. Microbial remediation of soils co-contaminated with 2,4-dichlorophenoxyacetic acid and cadmium

    SciTech Connect

    Roane, T.M.; Pepper, I.L. [Univ. of Arizona, Tucson, AZ (United States). Dept. of Soil, Water and Environmental Science

    1997-12-31

    One-third of organically-polluted sites are also contaminated with metals; however, the bioremediation potential of such sites is not clear. While metals are thought to inhibit the abilities of microbial communities to degrade organic pollutants, several microbial-metal resistance mechanisms are known to exist. This study utilizes cadmium-resistant soil microorganisms to enhance the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in the presence of cadmium. Cadmium-resistant bacteria were isolated from both a 40-year-old metal-contaminated soil and an uncontaminated soil. During growth experiments, it was found that the uncontaminated soil had a greater number of resistant isolates at low concentrations of cadmium, while the cadmium-contaminated soil exhibited higher microbial resistance with increased cadmium concentrations. ERIC PCR fingerprints discriminated among the cadmium-resistant isolates identified by BIOLOG as Bacillus, Corynecbacterium, Pseudomonas, and Xanthomonas spp. These isolates were resistant to concentrations ranging from 5 to 275 ppm soluble cadmium. In conventional degradation studies, two resistant isolates, a Bacillus and an unidentified Gram positive rod, supported the degradation of 500 ppm 2,4-D by the cadmium-sensitive 2,4-D degrader Alcaligenes eutrophus JMP134 in the presence of 20 and 40 ppm soluble cadmium, respectively.

  18. Long term effect of methylparathion contamination on soil microbial community diversity estimated by 16S rRNA gene cloning

    Microsoft Academic Search

    Ruifu Zhang; Jiandong Jiang; Ji-Dong Gu; Shunpeng Li

    2006-01-01

    The long-term effects of methylparathion contamination on the diversity of soil microbial community was investigated by a culture-independent approach using small subunit ribosomal RNA (SSU rRNA) gene-based cloning. Microbial DNA extracted from both the control soil sample and methylparathion contaminated soil sample was subjected to PCR amplification with primers specific for bacterial 16S rRNA gene sequences. From the PCR amplification

  19. 10 CFR Appendix D to Part 835 - Surface Contamination Values

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    The data presented in appendix D are to be used in identifying the need for posting of contamination and high contamination areas in accordance with § 835.603(e) and (f) and identifying the need for surface contamination monitoring and control in accordance with §§ 835.1101 and...

  20. Waveform tomography at a groundwater contamination site: Surface reflection data

    E-print Network

    Pratt, R. Gerhard

    Waveform tomography at a groundwater contamination site: Surface reflection data Fuchun Gao1 , Alan at a groundwater-contamination site at Hill Air Force Base in Utah. The paleochannel, which is incised of Superfund sites awaiting remedia- tion. The groundwater-contamination site at Hill Air Force Base HAFB

  1. Microbial Factors Rather Than Bioavailability Limit the Rate and Extent of PAH Biodegradation in Aged Crude Oil Contaminated Model Soils

    SciTech Connect

    Huesemann, Michael H.; Hausmann, Tom S.; Fortman, Timothy J.

    2002-08-01

    The rate and extent of PAH biodegradation in a set of aged, crude oil contaminated model soils were measured in 90-week slurry bioremediation experiments. Soil properties such as organic matter content, mineral type, particle diameter, surface area, and porosity did not significantly influence the PAH biodegradation kinetics among the ten different model soils. A comparison of aged and freshly spiked soils indicates that aging affects the biodegradation rates and extents only for higher molecular weight PAHs while the effects of aging are insignificant for 3-ring PAHs and total PAHs. In all model soils with the exception of kaolinite clay, the rate of abiotic desorption was faster than the rate of biodegradation during the initial phase of bioremediation treatment indicating that PAH biodegradation was limited by microbial factors. Similarly, any of the higher molecular weight PAHs that were still present after 90 weeks of treatment were released rapidly during abiotic desorption tests which demonstrates that bioavailability limitations were not responsible for the recalcitrance of these hydrocarbons. Indeed, an analysis of microbial counts indicates that a severe reduction in hydrocarbon degrader populations may be responsible for the observed incomplete PAH biodegradation. It can therefore be concluded that the recalcitrance of PAHs during bioremediation is not necessarily due to bioavailability limitations and that these residual contaminants might, therefore, pose a greater risk to environmental receptors than previously thought.

  2. Engineering microbial surfaces to degrade lignocellulosic biomass

    PubMed Central

    Huang, Grace L; Anderson, Timothy D; Clubb, Robert T

    2014-01-01

    Renewable lignocellulosic plant biomass is a promising feedstock from which to produce biofuels, chemicals, and materials. One approach to cost-effectively exploit this resource is to use consolidating bioprocessing (CBP) microbes that directly convert lignocellulose into valuable end products. Because many promising CBP-enabling microbes are non-cellulolytic, recent work has sought to engineer them to display multi-cellulase containing minicellulosomes that hydrolyze biomass more efficiently than isolated enzymes. In this review, we discuss progress in engineering the surfaces of the model microorganisms: Bacillus subtilis, Escherichia coli, and Saccharomyces cerevisiae. We compare the distinct approaches used to display cellulases and minicellulosomes, as well as their surface enzyme densities and cellulolytic activities. Thus far, minicellulosomes have only been grafted onto the surfaces of B. subtilis and S. cerevisiae, suggesting that the absence of an outer membrane in fungi and Gram-positive bacteria may make their surfaces better suited for displaying the elaborate multi-enzyme complexes needed to efficiently degrade lignocellulose. PMID:24430239

  3. Engineering microbial surfaces to degrade lignocellulosic biomass.

    PubMed

    Huang, Grace L; Anderson, Timothy D; Clubb, Robert T

    2014-01-01

    Renewable lignocellulosic plant biomass is a promising feedstock from which to produce biofuels, chemicals, and materials. One approach to cost-effectively exploit this resource is to use consolidating bioprocessing (CBP) microbes that directly convert lignocellulose into valuable end products. Because many promising CBP-enabling microbes are non-cellulolytic, recent work has sought to engineer them to display multi-cellulase containing minicellulosomes that hydrolyze biomass more efficiently than isolated enzymes. In this review, we discuss progress in engineering the surfaces of the model microorganisms: Bacillus subtilis, Escherichia coli, and Saccharomyces cerevisiae. We compare the distinct approaches used to display cellulases and minicellulosomes, as well as their surface enzyme densities and cellulolytic activities. Thus far, minicellulosomes have only been grafted onto the surfaces of B. subtilis and S. cerevisiae, suggesting that the absence of an outer membrane in fungi and Gram-positive bacteria may make their surfaces better suited for displaying the elaborate multi-enzyme complexes needed to efficiently degrade lignocellulose. PMID:24430239

  4. Modification of soil microbial activity and several hydrolases in a forest soil artificially contaminated with copper

    NASA Astrophysics Data System (ADS)

    Bellas, Rosa; Leirós, M? Carmen; Gil-Sotres, Fernando; Trasar-Cepeda, Carmen

    2010-05-01

    Soils have long been exposed to the adverse effects of human activities, which negatively affect soil biological activity. As a result of their functions and ubiquitous presence microorganisms can serve as environmental indicators of soil pollution. Some features of soil microorganisms, such as the microbial biomass size, respiration rate, and enzyme activity are often used as bioindicators of the ecotoxicity of heavy metals. Although copper is essential for microorganisms, excessive concentrations have a negative influence on processes mediated by microorganisms. In this study we measured the response of some microbial indicators to Cu pollution in a forest soil, with the aim of evaluating their potential for predicting Cu contamination. Samples of an Ah horizon from a forest soil under oakwood vegetation (Quercus robur L.) were contaminated in the laboratory with copper added at different doses (0, 120, 360, 1080 and 3240 mg kg-1) as CuCl2×2H2O. The soil samples were kept for 7 days at 25 °C and at a moisture content corresponding to the water holding capacity, and thereafter were analysed for carbon and nitrogen mineralization capacity, microbial biomass C, seed germination and root elongation tests, and for urease, phosphomonoesterase, catalase and ß-glucosidase activities. In addition, carbon mineralization kinetics were studied, by plotting the log of residual C against incubation time, and the metabolic coefficient, qCO2, was estimated. Both organic carbon and nitrogen mineralization were lower in polluted samples, with the greatest decrease observed in the sample contaminated with 1080 mg kg-1. In all samples carbon mineralization followed first order kinetics; the C mineralization constant was lower in contaminated than in uncontaminated samples and, in general, decreased with increasing doses of copper. Moreover, it appears that copper contamination not only reduced the N mineralization capacity, but also modified the N mineralization process, since in the contaminated samples all of the inorganic nitrogen was present as ammonium, probably because of inhibition of nitrification. There was a marked decrease in biomass-C with addition of copper, and the decrease was more acute at intermediate doses (average decrease, 73%). Despite the decreases in microbial biomass and mineralized C, the value of qCO2 increased after the addition of copper. Urease activity was strongly affected by the presence of copper and the decrease was proportional to the dose; the activity at the highest dose was only 96% of that in the uncontaminated sample. Phosphomonoesterase activity was also affected by addition of copper; the reduction in activity was less than for urease and the greatest reduction was observed for the dose of 1080 mg kg-1 of copper. Catalase activity was affected by the contamination, but no clear trend was observed in relation to the dose of copper. ß-glucosidase was scarcely modified by the contamination but an increase in activity was observed at the highest dose of copper. Seed germination was not affected by copper contamination, since it only showed a clear decrease for the sample contaminated with the highest dose of copper, while root elongation decreased sharply with doses higher than 120 mg kg-1 of copper. The combined germination-elongation index followed a similar pattern to that of root elongation. For all investigated properties showing a reduction of more than 50%, the response to copper contamination was fitted to a sigmoidal dose-response model, in order to estimate the ED50 values. The ED50 values were calculated for microbial biomass, urease, root elongation and germination-elongation index, and similar values were obtained, ranging from 340 to 405 mg kg-1 Cu. The ED50 values may therefore provide a good estimation of soil deterioration.

  5. Widespread potential for microbial MTBE degradation in surface-water sediments

    USGS Publications Warehouse

    Bradley, P.M.; Landmeyer, J.E.; Chapelle, F.H.

    2001-01-01

    Microorganisms indigenous to stream and lake bed sediments, collected from 11 sites throughout the United States, demonstrated significant mineralization of the fuel oxygenate, methyl-tert-butyl ether (MTBE). Mineralization of [U-14C]MTBE to 14CO2 ranged from 15 to 66% over 50 days and did not differ significantly between sediments collected from MTBE contaminated sites and from sites with no history of MTBE exposure. This result suggests that even the microbial communities indigenous to newly contaminated surface water systems will exhibit some innate ability to attenuate MTBE under aerobic conditions. The magnitude of MTBE mineralization was related to the sediment grain size distribution. A pronounced, inverse correlation (p < 0.001; r2 = 0.73) was observed between the final recovery of 14CO2 and the percentage content of silt and clay sized grains (grain diameter < 0.125 mm). The results of this study indicate that the microorganisms that inhabit the bed sediments of streams and lakes can degrade MTBE efficiently and that this capability is widespread in the environment. Thus aerobic bed sediment microbial processes may provide a significant environmental sink for MTBE in surface water systems throughout the United States and may contribute to the reported transience of MTBE in some surface waters.

  6. Study on contaminants on flight and other critical surfaces

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Hughes, Charles; Arendale, William F.

    1994-01-01

    The control of surface contamination in the manufacture of space hardware can become a critical step in the production process. Bonded surfaces have been shown to be affected markedly by contamination. It is important to insure surface cleanliness by preventing contamination prior to bonding. In this vein techniques are needed in which the contamination which may affect bonding are easily found and removed. Likewise, if materials which are detrimental to bonding are not easily removed, then they should not be used in the manufacturing process. This study will address the development of techniques to locate and quantify contamination levels of particular contaminants. With other data becoming available from MSFC and its contractors, this study will also quantify how certain contaminants affect bondlines and how easily they are removed in manufacturing.

  7. Mathematical modeling the cross-contamination of Escherichia coli O157:H7 on the surface of ready-to-eat meat product while slicing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microbial cross-contamination either at home or production site is one of the major factors of causing contamination of foods and leading to the foodborne illness. The knowledge regarding Escherichia coli O157:H7 surface transfer on ready-to-eat (RTE) deli meat and the slicer used for slicing diffe...

  8. Tailored carbon nanotube immunosensors for the detection of microbial contamination.

    PubMed

    Prieto-Simón, B; Bandaru, N M; Saint, C; Voelcker, N H

    2015-05-15

    The use of carbon nanotubes (CNTs) as building blocks in the design of electrochemical biosensors has been attracting attention over the last few years, mainly due to their high electrical conductivity and large surface area. Here, we present two approaches based on tailored single-walled CNTs (SWCNTs) architectures to develop immunosensors for the bacteriophage MS2, a virus often detected in sewage-impacted water supplies. In the first approach, SWCNTs were used in the bottom-up design of sensors as antibody immobilization support. Carboxy-functionalised SWCNTs were covalently tethered onto gold electrodes via carbodiimide coupling to cysteamine-modified gold electrodes. These SWCNTs were hydrazide functionalized by electrochemical grafting of diazonium salts. Site-oriented immobilization of antibodies was then carried out through hydrazone bond formation. Results showed microarray electrode behavior, greatly improving the signal-to-noise ratio. Excellent sensitivity and limit of detection (9.3 pfu/mL and 9.8 pfu/mL in buffer and in river water, respectively) were achieved, due to the combination of the SWCNTs' ability to promote electron transfer reactions with electroactive species at low overpotentials and their high surface-to-volume ratio providing a favorable environment to immobilize biomolecules. In the second approach, SWCNTs were decorated with iron oxide nanoparticles. Diazonium salts were electrochemically grafted on iron-oxide-nanoparticle-decorated SWCNTs to functionalize them with hydrazide groups that facilitate site-directed immobilization of antibodies via hydrazone coupling. These magnetic immunocarriers facilitated MS2 separation and concentration on an electrode surface. This approach minimized non-specific adsorptions and matrix effects and allowed low limits of detection (12 pfu/mL and 39 pfu/mL in buffer and in river water, respectively) that could be further decreased by incubating the magnetic immunocarriers with larger volumes of sample. Significantly, both approaches permitted the detection of MS2 to levels regularly encountered in sewage-impacted environments. PMID:25316087

  9. Spatial patterns of microbial diversity and activity in an aged creosote-contaminated site.

    PubMed

    Mukherjee, Shinjini; Juottonen, Heli; Siivonen, Pauli; Lloret Quesada, Cosme; Tuomi, Pirjo; Pulkkinen, Pertti; Yrjälä, Kim

    2014-10-01

    Restoration of polluted sites via in situ bioremediation relies heavily on the indigenous microbes and their activities. Spatial heterogeneity of microbial populations, contaminants and soil chemical parameters on such sites is a major hurdle in optimizing and implementing an appropriate bioremediation regime. We performed a grid-based sampling of an aged creosote-contaminated site followed by geostatistical modelling to illustrate the spatial patterns of microbial diversity and activity and to relate these patterns to the distribution of pollutants. Spatial distribution of bacterial groups unveiled patterns of niche differentiation regulated by patchy distribution of pollutants and an east-to-west pH gradient at the studied site. Proteobacteria clearly dominated in the hot spots of creosote pollution, whereas the abundance of Actinobacteria, TM7 and Planctomycetes was considerably reduced from the hot spots. The pH preferences of proteobacterial groups dominating in pollution could be recognized by examining the order and family-level responses. Acidobacterial classes came across as generalists in hydrocarbon pollution whose spatial distribution seemed to be regulated solely by the pH gradient. Although the community evenness decreased in the heavily polluted zones, basal respiration and fluorescein diacetate hydrolysis rates were higher, indicating the adaptation of specific indigenous microbial populations to hydrocarbon pollution. Combining the information from the kriged maps of microbial and soil chemistry data provided a comprehensive understanding of the long-term impacts of creosote pollution on the subsurface microbial communities. This study also highlighted the prospect of interpreting taxa-specific spatial patterns and applying them as indicators or proxies for monitoring polluted sites. PMID:25105905

  10. Metal-Macrofauna Interactions Determine Microbial Community Structure and Function in Copper Contaminated Sediments

    PubMed Central

    Mayor, Daniel J.; Gray, Nia B.; Elver-Evans, Joanna; Midwood, Andrew J.; Thornton, Barry

    2013-01-01

    Copper is essential for healthy cellular functioning, but this heavy metal quickly becomes toxic when supply exceeds demand. Marine sediments receive widespread and increasing levels of copper contamination from antifouling paints owing to the 2008 global ban of organotin-based products. The toxicity of copper will increase in the coming years as seawater pH decreases and temperature increases. We used a factorial mesocosm experiment to investigate how increasing sediment copper concentrations and the presence of a cosmopolitan bioturbating amphipod, Corophium volutator, affected a range of ecosystem functions in a soft sediment microbial community. The effects of copper on benthic nutrient release, bacterial biomass, microbial community structure and the isotopic composition of individual microbial membrane [phospholipid] fatty acids (PLFAs) all differed in the presence of C. volutator. Our data consistently demonstrate that copper contamination of global waterways will have pervasive effects on the metabolic functioning of benthic communities that cannot be predicted from copper concentrations alone; impacts will depend upon the resident macrofauna and their capacity for bioturbation. This finding poses a major challenge for those attempting to manage the impacts of copper contamination on ecosystem services, e.g. carbon and nutrient cycling, across different habitats. Our work also highlights the paucity of information on the processes that result in isotopic fractionation in natural marine microbial communities. We conclude that the assimilative capacity of benthic microbes will become progressively impaired as copper concentrations increase. These effects will, to an extent, be mitigated by the presence of bioturbating animals and possibly other processes that increase the influx of oxygenated seawater into the sediments. Our findings support the move towards an ecosystem approach for environmental management. PMID:23741430

  11. Metal-macrofauna interactions determine microbial community structure and function in copper contaminated sediments.

    PubMed

    Mayor, Daniel J; Gray, Nia B; Elver-Evans, Joanna; Midwood, Andrew J; Thornton, Barry

    2013-01-01

    Copper is essential for healthy cellular functioning, but this heavy metal quickly becomes toxic when supply exceeds demand. Marine sediments receive widespread and increasing levels of copper contamination from antifouling paints owing to the 2008 global ban of organotin-based products. The toxicity of copper will increase in the coming years as seawater pH decreases and temperature increases. We used a factorial mesocosm experiment to investigate how increasing sediment copper concentrations and the presence of a cosmopolitan bioturbating amphipod, Corophium volutator, affected a range of ecosystem functions in a soft sediment microbial community. The effects of copper on benthic nutrient release, bacterial biomass, microbial community structure and the isotopic composition of individual microbial membrane [phospholipid] fatty acids (PLFAs) all differed in the presence of C. volutator. Our data consistently demonstrate that copper contamination of global waterways will have pervasive effects on the metabolic functioning of benthic communities that cannot be predicted from copper concentrations alone; impacts will depend upon the resident macrofauna and their capacity for bioturbation. This finding poses a major challenge for those attempting to manage the impacts of copper contamination on ecosystem services, e.g. carbon and nutrient cycling, across different habitats. Our work also highlights the paucity of information on the processes that result in isotopic fractionation in natural marine microbial communities. We conclude that the assimilative capacity of benthic microbes will become progressively impaired as copper concentrations increase. These effects will, to an extent, be mitigated by the presence of bioturbating animals and possibly other processes that increase the influx of oxygenated seawater into the sediments. Our findings support the move towards an ecosystem approach for environmental management. PMID:23741430

  12. An Auger electron spectroscopy study of surface-preparation contaminants

    NASA Technical Reports Server (NTRS)

    Wu, D.; Stephens, R. M.; Outlaw, R. A.; Hopson, P.

    1990-01-01

    There are many cleaning techniques that are presently being employed for surface preparation of materials that are subsequently exposed to ultrahigh vacuum (UHV). Unfortunately, there are virtually no comparative measurements which establish the residual contaminant level of each method. In this report, eleven different cleaning methods, ranging from only detergent cleaning to electrochemical polishing, were applied to identical samples of 347 stainless steel. Two surface conditions, a standard machined surface and a mechanically polished surface, were studied. Auger electron spectroscopy (AES) within a UHV environment was then used to detect the types of contaminants and the magnitudes found on the sample surfaces. It was found that the electrochemical polishing gave the least contaminated surface of all metals studied and that mechanically polished surfaces were significantly cleaner than the as-machined surfaces for any given cleaning method. Furthermore, it was also found that the residual contaminations left by methanol, ethanol, isopropyl alcohol, acetone, and freon finishing rinses are almost the same.

  13. Microbial activity in an acid resin deposit: biodegradation potential and ecotoxicology in an extremely acidic hydrocarbon contamination.

    PubMed

    Kloos, Karin; Schloter, Michael; Meyer, Ortwin

    2006-11-01

    Acid resins are residues produced in a recycling process for used oils that was in use in the forties and fifties of the last century. The resin-like material is highly contaminated with mineral oil hydrocarbons, extremely acidic and co-contaminated with substituted and aromatic hydrocarbons, and heavy metals. To determine the potential for microbial biodegradation the acid resin deposit and its surroundings were screened for microbial activity by soil respiration measurements. No microbial activity was found in the core deposit. However, biodegradation of hydrocarbons was possible in zones with a lower degree of contamination surrounding the deposit. An extreme acidophilic microbial community was detected close to the core deposit. With a simple ecotoxicological approach it could be shown that the pure acid resin that formed the major part of the core deposit, was toxic to the indigenous microflora due to its extremely low pH of 0-1. PMID:16530313

  14. Surface contaminants inhibit osseointegration in a novel murine model

    Microsoft Academic Search

    Lindsay A. Bonsignore; Robb W. Colbrunn; Joscelyn M. Tatro; Patrick J. Messerschmitt; Christopher J. Hernandez; Victor M. Goldberg; Matthew C. Stewart; Edward M. Greenfield

    2011-01-01

    Surface contaminants, such as bacterial debris and manufacturing residues, may remain on orthopedic implants after sterilization procedures and affect osseointegration. The goals of this study were to develop a murine model of osseointegration in order to determine whether removing surface contaminants enhances osseointegration. To develop the murine model, titanium alloy implants were implanted into a unicortical pilot hole in the

  15. Distribution of microbial physiologic types in an aquifer contaminated by crude oil

    USGS Publications Warehouse

    Bekins, B.A.; Godsy, E.M.; Warren, E.

    1999-01-01

    We conducted a plume-scale study of the microbial ecology in the anaerobic portion of an aquifer contaminated by crude-oil compounds. The data provide insight into the patterns of ecological succession, microbial nutrient demands, and the relative importance of free-living versus attached microbial populations. The most probable number (MPN) method was used to characterize the spatial distribution of six physiologic types: aerobes, denitrifiers, iron-reducers, heterotrophic fermenters, sulfate-reducers, and methanogens. Both free-living and attached numbers were determined over a broad cross-section of the aquifer extending horizontally from the source of the plume at a nonaqueous oil body to 66 m downgradient, and vertically from above the water table to the base of the plume below the water table. Point samples from widely spaced locations were combined with three closely spaced vertical profiles to create a map of physiologic zones for a cross-section of the plume. Although some estimates suggest that less than 1% of the subsurface microbial population can be grown in laboratory cultures, the MPN results presented here provide a comprehensive qualitative picture of the microbial ecology at the plume scale. Areas in the plume that are evolving from iron-reducing to methanogenic conditions are clearly delineated and generally occupy 25-50% of the plume thickness. Lower microbial numbers below the water table compared to the unsaturated zone suggest that nutrient limitations may be important in limiting growth in the saturated zone. Finally, the data indicate that an average of 15% of the total population is suspended.

  16. Relationship between microbial diversity and chemical contamination along a 50-year-old sediment core

    NASA Astrophysics Data System (ADS)

    Berthe, T.; Petit, F.; Boust, D.; Lesueur, P.; Roose-Amsaleg, C.; Cécillon, S.; Kaci-Benaicha, A.

    2013-12-01

    The purpose of this study was to evaluate the potential use of sediment microbial diversity (community structure) as an indicator of the impact of anthropogenic activities within an estuarine ecosystem. The diversity of microbial communities was investigated along a 5-m-long sediment core collected in an anthropized European estuary (Seine, France), giving an evolution of trace metal, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) concentrations over the last 50 years. An increase of trace metal and PCB concentrations are observed with depth, with an enrichment of these contaminants in the 1970s. The concentration profiles of light, intermediate and heavy PAHs showed distinct peaks, but the highest total PAH concentration was also detected in the sediment from the 1970s. We first investigated the bacterial community resistant to cobalt, zinc and cadmium by analyzing the diversity of the czcA gene encoding an RND efflux pump (Heavy Metal Efflux-RND) in 5-year and 33-year-old sediment samples displaying contrasted concentrations in these trace metals. The diversity of the czcA gene was reduced in the 33-year-old and more contaminated sediments suggesting a selection of resistant bacterial species. A molecular fingerprinting method (DGGE) was used to study the evolution of total microbial (Bacteria and Archaea) community structures for samples selected along the sediment core. A correlation is observed between the bacterial community structures, the sediment age, the trace metal and PAH concentrations. The metabolically active and total microbial communities were further characterized by a microarray approach (Phylochips) in sediment samples selected according to the DGGE results. Bacterial diversity was found dominated by Proteobacteria, Actinobacteria, and Firmicutes in all analyzed samples. Diversity of phylotypes corresponds to changes in PAH and trace metal concentrations in sediment, suggesting that chemical contaminants have selected for well-adapted taxa. In addition, the taxa able to survive and remain active within the contaminated sediments have been identified by characterizing the metabolically active fraction of the microbial communities. This metabolically active community is dominated by the same phyla but different classes are observed.

  17. Metal impacts on microbial biomass in the anoxic sediments of a contaminated lake

    SciTech Connect

    Gough, Heidi L.; Dahl, Amy L.; Nolan, Melissa A.; Gaillard, Jean-Francois; Stahl, David A.

    2008-04-26

    Little is known about the long-term impacts of metal contamination on the microbiota of anoxic lake sediments. In this study, we examined microbial biomass and metals (arsenic, cadmium, chromium, copper, iron, lead, manganese, and zinc) in the sediments of Lake DePue, a backwater lake located near a former zinc smelter. Sediment core samples were examined using two independent measures for microbial biomass (total microscopic counts and total phospholipid-phosphate concentrations), and for various fractions of each metal (pore water extracts, sequential extractions, and total extracts of all studied metals and zinc speciation by X-ray absorption fine structure (XAFS). Zinc concentrations were up to 1000 times higher than reported for sediments in the adjacent Illinois River, and ranged from 21,400 mg/kg near the source to 1,680 mg/kg near the river. However, solid metal fractions were not well correlated with pore water concentrations, and were not good predictors of biomass concentrations. Instead, biomass, which varied among sites by as much as two-times, was inversely correlated with concentrations of pore water zinc and arsenic as established by multiple linear regression. Monitoring of other parameters known to naturally influence biomass in sediments (e.g., organic carbon concentrations, nitrogen concentrations, pH, sediment texture, and macrophytes) revealed no differences that could explain observed biomass trends. This study provides strong support for control of microbial abundance by pore water metal concentrations in contaminated freshwater sediments.

  18. The surface stress theory of microbial morphogenesis.

    PubMed

    Koch, A L

    1983-01-01

    From the physics of the situation, one might conclude that the osmotic pressure within most prokaryotes creates a sufficiently high tension in the wall that organisms are at risk of ripping themselves apart. The Surface Stress Theory holds that they avoid this, and are able to carry out certain morphogenetic processes by linking the cleavages of appropriate bonds to enzymes that are sensitive to the stress in the bonds under attack. This tends to maintain the internal pressure and couples wall growth to cytoplasmic growth. Mechanisms with widely different geometry function for different organisms, but they have in common the requirement that new murein be covalently linked, and usually in an unextended conformation. Organisms differ in the site of wall addition and site of cleavage. In the Gram-positive Streptococcus, septum formation, and septal splitting occurs with little stretching of the unsplit septum. In Gram-positive bacilli, the cylinder grows by the inside-to-outside mechanism, and the poles appear to be formed by a split-and-stretch mechanism. Gram-negative rods, with their much thinner wall, resist a spherical shape and are capable of cell division by altering the biochemical mechanism so that initially one-third to one-fifth of the pressure-volume work required to increase the area of the side wall is needed to increase that in a developing pole. The growth of hyphae is a separate case; it requires that much less work is needed to force growth of the apex relative to the side wall. Some other bacterial shapes also can be explained by the theory. But at present, it is only a theory, although it is gradually becoming capable of accounting for current observations in detail. Its importance is that it prescribes many experiments that now need to be done. PMID:6364728

  19. Dynamics of Coupled Contaminant and Microbial Transport in Heterogeneous Porous Media: Purdue Component

    SciTech Connect

    Cushman, J.H.

    2000-06-01

    Dynamic microbial attachment/detachment occurs in subsurface systems in response to changing environmental conditions caused by contaminant movement and degradation. Understanding the environmental conditions and mechanisms by which anaerobic bacteria partition between aqueous and solid phases is a critical requirement for designing and evaluating in situ bioremediation efforts. This interdisciplinary research project, of which we report only the Purdue contribution, provides fundamental information on the attachment/detachment dynamics of bacteria in heterogeneous porous media. Fundamental results from the Purdue collaboration are: (a) development of a matched-index method for obtaining 3-D Lagrangian trajectories of microbial sized particles transporting within porous media or microflow cells, (b) application of advanced numerical methods to optimally design a microflow cell for studying anaerobic bacterial attachment/detachment phenomena, (c) development of two types of models for simulating bacterial movement and attachment/detachment in microflow cells and natural porous media, (d) application of stochastic analysis to upscale pore scale microbial attachment/detachment models to natural heterogeneous porous media, and (e) evaluation of the role nonlocality plays in microbial dynamics in heterogeneous porous media.

  20. Dynamics of Coupled Contaminant and Microbial Transport in Heterogeneous Porous Media: Purdue Component

    SciTech Connect

    Cushman, J.H.; Madilyn Fletcher

    2000-06-01

    Dynamic microbial attachment/detachment occurs in subsurface systems in response to changing environmental conditions caused by contaminant movement and degradation. Understanding the environmental conditions and mechanisms by which anaerobic bacteria partition between aqueous and solid phases is a critical requirement for designing and evaluating in situ bioremediation efforts. This interdisciplinary research project, of which we report only the Purdue contribution, provides fundamental information on the attachment/detachment dynamics of bacteria in heterogeneous porous media. Fundamental results from the Purdue collaboration are: (a) development of a matched-index method for obtaining 3-D Lagrangian trajectories of microbial sized particles transporting within porous media or microflow cells, (b) application of advanced numerical methods to optimally design a microflow cell for studying anaerobic bacterial attachment/detachment phenomena, (c) development of two types of models for simulating bacterial movement and attachment/detachment in microflow cells and natural porous media, (d) application of stochastic analysis to upscale pore scale microbial attachment/detachment models to natural heterogeneous porous media, and (e) evaluation of the role nonlocality plays in microbial dynamics in heterogeneous porous media

  1. Hydrocarbon degrading microbial communities in bench scale aerobic biobarriers for gasoline contaminated groundwater treatment.

    PubMed

    Daghio, Matteo; Tatangelo, Valeria; Franzetti, Andrea; Gandolfi, Isabella; Papacchini, Maddalena; Careghini, Alessandro; Sezenna, Elena; Saponaro, Sabrina; Bestetti, Giuseppina

    2015-07-01

    BTEX compounds (benzene, toluene, ethylbenzene and xylenes) and methyl tert-butyl ether (MTBE) are some of the main constituents of gasoline and can be accidentally released in the environment. In this work the effect of bioaugmentation on the microbial communities in a bench scale aerobic biobarrier for gasoline contaminated water treatment was studied by 16S rRNA gene sequencing. Catabolic genes (tmoA and xylM) were quantified by qPCR, in order to estimate the biodegradation potential, and the abundance of total bacteria was estimated by the quantification of the number of copies of the 16S rRNA gene. Hydrocarbon concentration was monitored over time and no difference in the removal efficiency for the tested conditions was observed, either with or without the microbial inoculum. In the column without the inoculum the most abundant genera were Acidovorax, Bdellovibrio, Hydrogenophaga, Pseudoxanthomonas and Serpens at the beginning of the column, while at the end of the column Thauera became dominant. In the inoculated test the microbial inoculum, composed by Rhodococcus sp. CE461, Rhodococcus sp. CT451 and Methylibium petroleiphilum LMG 22953, was outcompeted. Quantitative PCR results showed an increasing in xylM copy number, indicating that hydrocarbon degrading bacteria were selected during the treatment, although only a low increase of the total biomass was observed. However, the bioaugmentation did not lead to an increase in the degradative potential of the microbial communities. PMID:25747304

  2. Microbial Community Responses to Organophosphate Substrate Additions in Contaminated Subsurface Sediments

    PubMed Central

    Martinez, Robert J.; Wu, Cindy H.; Beazley, Melanie J.; Andersen, Gary L.; Conrad, Mark E.; Hazen, Terry C.; Taillefert, Martial; Sobecky, Patricia A.

    2014-01-01

    Background Radionuclide- and heavy metal-contaminated subsurface sediments remain a legacy of Cold War nuclear weapons research and recent nuclear power plant failures. Within such contaminated sediments, remediation activities are necessary to mitigate groundwater contamination. A promising approach makes use of extant microbial communities capable of hydrolyzing organophosphate substrates to promote mineralization of soluble contaminants within deep subsurface environments. Methodology/Principal Findings Uranium-contaminated sediments from the U.S. Department of Energy Oak Ridge Field Research Center (ORFRC) Area 2 site were used in slurry experiments to identify microbial communities involved in hydrolysis of 10 mM organophosphate amendments [i.e., glycerol-2-phosphate (G2P) or glycerol-3-phosphate (G3P)] in synthetic groundwater at pH 5.5 and pH 6.8. Following 36 day (G2P) and 20 day (G3P) amended treatments, maximum phosphate (PO43?) concentrations of 4.8 mM and 8.9 mM were measured, respectively. Use of the PhyloChip 16S rRNA microarray identified 2,120 archaeal and bacterial taxa representing 46 phyla, 66 classes, 110 orders, and 186 families among all treatments. Measures of archaeal and bacterial richness were lowest under G2P (pH 5.5) treatments and greatest with G3P (pH 6.8) treatments. Members of the phyla Crenarchaeota, Euryarchaeota, Bacteroidetes, and Proteobacteria demonstrated the greatest enrichment in response to organophosphate amendments and the OTUs that increased in relative abundance by 2-fold or greater accounted for 9%–50% and 3%–17% of total detected Archaea and Bacteria, respectively. Conclusions/Significance This work provided a characterization of the distinct ORFRC subsurface microbial communities that contributed to increased concentrations of extracellular phosphate via hydrolysis of organophosphate substrate amendments. Within subsurface environments that are not ideal for reductive precipitation of uranium, strategies that harness microbial phosphate metabolism to promote uranium phosphate precipitation could offer an alternative approach for in situ sequestration. PMID:24950228

  3. ISSUES IN UNDERSTANDING DERMAL EXPOSURES RESULTING FROM CONTACT WITH CONTAMINATED SURFACES, MEASURING SURFACE CONTAMINATION, AND CHARACTERIZING TRANSFERS

    EPA Science Inventory

    Although monitoring for surface contamination in work with radioactive materials and dermal monitoring of pesticide exposure to agricultural workers have been standard practice for 50 years, regular surface sampling and dermal monitoring methods have only been applied to indust...

  4. Surface contamination monitoring by the measurement of scattering distribution functions

    NASA Technical Reports Server (NTRS)

    Carosso, Paola A.; Pugel, Nancy J.

    1987-01-01

    This paper describes the use of Bidirectional Scattering Distribution Functions (BSDF) to quantify surface degradation, thus providing an effective method for contamination monitoring. This approach to contamination monitoring is based on the use of witness surfaces (mirrors or glass slides) located next to the critical surfaces. Contaminant accretion can be monitored during all phases of spacecraft fabrication, assembly, and testing. The method can be applied in other areas of contamination control such as monitoring of clean room environments. The BSDF can also prove extremely useful in establishing contamination control requirements and acceptability criteria. This paper describes the apparatus adopted to perform BSDF measurements and discusses some practical aspects of data collection. The results obtained in contamination monitoring programs performed at the NASA Goddard Space Flight Center are presented. Some possible new applications of this monitoring technique are also addressed.

  5. Contamination analyses of technology mirror assembly optical surfaces

    NASA Astrophysics Data System (ADS)

    Germani, Mark S.

    1991-09-01

    Automated electron microprobe analyses were performed on tape lift samples from the Technology Mirror Assembly (TMA) optical surfaces. Details of the analyses are given, and the contamination of the mirror surfaces is discussed. Based on the automated analyses of the tape lifts from the TMA surfaces and the control blank, we can conclude that the particles identified on the actual samples were not a result of contamination due to the handling or sampling process itself and that the particles reflect the actual contamination on the surface of the mirror.

  6. Contamination analyses of technology mirror assembly optical surfaces

    NASA Technical Reports Server (NTRS)

    Germani, Mark S.

    1991-01-01

    Automated electron microprobe analyses were performed on tape lift samples from the Technology Mirror Assembly (TMA) optical surfaces. Details of the analyses are given, and the contamination of the mirror surfaces is discussed. Based on the automated analyses of the tape lifts from the TMA surfaces and the control blank, we can conclude that the particles identified on the actual samples were not a result of contamination due to the handling or sampling process itself and that the particles reflect the actual contamination on the surface of the mirror.

  7. Dynamics of coupled contaminant and microbial transport in heterogeneous porous media. 1998 annual progress report

    SciTech Connect

    Ginn, T.R.; Cushman, J.H.; Murphy, E.M.; Fletcher, M.

    1998-06-01

    'Dynamic microbial attachment/detachment occurs in subsurface systems in response to changing environmental conditions caused by contaminant movement and degradation. Understanding the environmental conditions and mechanisms by which anaerobic bacteria partition between aqueous and solid phases is a critical requirement for designing and evaluating in-situ bioremediation efforts. This interdisciplinary research project will provide fundamental information on the attachment/detachment dynamics of anaerobic bacteria in heterogeneous porous media under growth and growth-limiting conditions. Experiments will provide information on passive and active attachment/detachment mechanisms used by growing anaerobes capable of reductive dechlorination. Theoretical representations of these attachment/detachment mechanisms will be incorporated into existing flow and transport models that incorporate heterogeneity effects and can be used to predict behavior at field scales. These mechanistic-based models will be tested against experimental data provided through controlled laboratory experiments in heterogeneous porous media in large (meter-scale) 2-D flow cells. In addition to a mechanistic-based predictive model, this research will lead to new theories for the transient spatial distribution of microbial populations and contaminant plumes in heterogeneous porous media, improving the capability for designing staged remediation strategies for dealing with mixed contaminants.'

  8. Microbial Contamination of the White Coats of Dental Staff in the Clinical Setting

    PubMed Central

    Priya, Harsh; Acharya, Shashidhar; Bhat, Meghashyam; Ballal, Mamtha

    2009-01-01

    Background and aims Although wearing a white coat is an accepted part of medical and dental practice, it is a potential source of cross-infection. The objective of this study was to determine the level and type of microbial contamination present on the white coats of dental interns, graduate students and faculty in a dental clinic. Materials and methods Questionnaire and cross-sectional survey of the bacterial contamination of white coats in two predetermined areas (chest and pocket) on the white coats were done in a rural dental care center. Paired sample t-test and chi-square test were used for Statistical analysis. Results 60.8% of the participants reported washing their white coats once a week. Grading by the examiner revealed 15.7% dirty white coats. Also, 82.5% of the interns showed bacterial contamination of their white coats compared to 74.7% graduate students and 75% faculty members irrespective of the area examined. However, chest area was consistently a more bacterio-logically contaminated site as compared to the pocket area. Antibiotic sensitivity testing revealed resistant varieties of micro-organisms against Amoxicillin (60%), Erythromycin (42.5%) and Cotrimoxazole (35.2%). Conclusion The white coats seem to be a potential source of cross-infection in the dental setting. The bacterial contamina-tion carried by white coats, as demonstrated in this study, supports the ban on white coats from non-clinical areas. PMID:23230502

  9. Microbial in situ degradation of aromatic hydrocarbons in a contaminated aquifer monitored by carbon isotope fractionation

    NASA Astrophysics Data System (ADS)

    Richnow, Hans H.; Annweiler, Eva; Michaelis, Walter; Meckenstock, Rainer U.

    2003-08-01

    We present an approach for characterizing in situ microbial degradation using the 13C/ 12C isotope fractionation of contaminants as an indicator of biodegradation. The 13C/ 12C isotope fractionation of aromatic hydrocarbons was studied in anoxic laboratory soil percolation columns with toluene or o-xylene as the sole carbon and electron source, and sulfate as electron acceptor. After approximately 2 months' of incubation, the soil microbial community degraded 32 mg toluene l -1 and 44 mg o-xylene l -1 to less than 0.05 mg l -1, generating a stable concentration gradient in the column. The 13C/ 12C isotope ratio in the residual non-degraded fraction of toluene and o-xylene increased significantly, corresponding to isotope fractionation factors (?C) of 1.0015 and 1.0011, respectively. When the extent of biodegradation in the soil column was calculated based on the measured isotope ratios ( Rt) and an isotope fractionation factor (?C=1.0017) obtained from a sulfate-reducing batch culture the theoretical residual substrate concentrations ( Ct) matched the measured toluene concentrations in the column. This indicated that a calculation of biodegradation based on isotope fractionation could work in systems like soil columns. In a field study, a polluted, anoxic aquifer was analyzed for BTEX and PAH contaminants. These compounds were found to exhibit a significant concentration gradient along an 800-m groundwater flow path downstream of the source of contamination. A distinct increase in the carbon isotope ratio ( ?13C) was observed for the residual non-degraded toluene (7.2‰), o-xylene (8.1‰) and naphthalene fractions (1.2‰). Based on the isotope values and the laboratory-derived isotope fractionation factors for toluene and o-xylene, the extent to which the residual substrate fraction in the monitoring wells had been degraded by microorganisms was calculated. The results revealed significant biodegradation along the groundwater flow path. In the wells at the end of the plume, the bioavailable toluene and o-xylene fractions had been almost completely reduced by in situ microbial degradation. Although indane and indene showed decreasing concentrations downstream of the groundwater flow path, suggesting microbial degradation, their carbon isotope ratios remained constant. As the physical properties of these compounds are similar to those of BTEX compounds, the constant isotope values of indane and indene indicated that microbial degradation did not lead to isotope fractionation of all aromatic hydrocarbons. In addition, physical interaction with the aquifer material during the groundwater passage did not significantly alter the carbon isotope composition of aromatic hydrocarbons.

  10. Microbial Diversity and Bioremediation of a Hydrocarbon-Contaminated Aquifer (Vega Baja, Puerto Rico)

    SciTech Connect

    Rodriguez-Martinex, Enid M. [University of Puerto Rico; Perez, Ernie [University of Puerto Rico; Schadt, Christopher Warren [ORNL; Zhou, Jizhong [University of Oklahoma; Massol-Deya, Arturo A. [University of Puerto Rico

    2006-01-01

    Hydrocarbon contamination of groundwater resources has become a major environmental and human health concern in many parts of the world. Our objectives were to employ both culture and culture-independent techniques to characterize the dynamics of microbial community structure within a fluidized bed reactor used to bioremediate a diesel-contaminated groundwater in a tropical environment. Under normal operating conditions, 97 to 99% of total hydrocarbons were removed with only 14 min hydraulic retention time. Over 25 different cultures were isolated from the treatment unit (96% which utilized diesel constituents as sole carbon source). Approximately 20% of the isolates were also capable of complete denitrification to nitrogen gas. Sequence analysis of 16S rDNA demonstrated ample diversity with most belonging to the {infinity}, {beta} and {gamma} subdivision of the Proteobacteria, Bacilli, and Actinobacteria groups. Moreover, the genetic constitution of the microbial community was examined at multiple time points with a Functional Gene Array (FGA) containing over 12,000 probes for genes involved in organic degradation and major biogeochemical cycles. Total community DNA was extracted and amplified using an isothermal {phi}29 polymerase-based technique, labeled with Cy5 dye, and hybridized to the arrays in 50% formimide overnight at 50 C. Cluster analysis revealed comparable profiles over the course of treatment suggesting the early selection of a very stable microbial community. A total of 270 genes for organic contaminant degradation (including naphthalene, toluene [aerobic and anaerobic], octane, biphenyl, pyrene, xylene, phenanthrene, and benzene); and 333 genes involved in metabolic activities (nitrite and nitrous oxide reductases [nirS, nirK, and nosZ], dissimilatory sulfite reductases [dsrAB], potential metal reducing C-type cytochromes, and methane monooxygenase [pmoA]) were repeatedly detected. Genes for degradation of MTBE, nitroaromatics and chlorinated compounds were also present, indicating a broad catabolic potential of the treatment unit. FGA's demonstrated the early establishment of a diverse community with concurrent aerobic and anaerobic processes contributing to the bioremediation process.

  11. Microbial Diversity and Bioremediation of a Hydrocarbon-Contaminated Aquifer (Vega Baja, Puerto Rico)

    PubMed Central

    Rodríguez-Martínez, Enid M.; Pérez, Ernie X.; Schadt, Christopher W.; Zhou, Jizhong; Massol-Deyá, Arturo A.

    2006-01-01

    Hydrocarbon contamination of groundwater resources has become a major environmental and human health concern in many parts of the world. Our objectives were to employ both culture and culture-independent techniques to characterize the dynamics of microbial community structure within a fluidized bed reactor used to bioremediate a diesel-contaminated groundwater in a tropical environment. Under normal operating conditions, 97 to 99% of total hydrocarbons were removed with only 14 min hydraulic retention time. Over 25 different cultures were isolated from the treatment unit (96% which utilized diesel constituents as sole carbon source). Approximately 20% of the isolates were also capable of complete denitrification to nitrogen gas. Sequence analysis of 16S rDNA demonstrated ample diversity with most belonging to the ?, ? and ? subdivision of the Proteobacteria, Bacilli, and Actinobacteria groups. Moreover, the genetic constitution of the microbial community was examined at multiple time points with a Functional Gene Array (FGA) containing over 12,000 probes for genes involved in organic degradation and major biogeochemical cycles. Total community DNA was extracted and amplified using an isothermal ?29 polymerase-based technique, labeled with Cy5 dye, and hybridized to the arrays in 50% formimide overnight at 50°C. Cluster analysis revealed comparable profiles over the course of treatment suggesting the early selection of a very stable microbial community. A total of 270 genes for organic contaminant degradation (including naphthalene, toluene [aerobic and anaerobic], octane, biphenyl, pyrene, xylene, phenanthrene, and benzene); and 333 genes involved in metabolic activities (nitrite and nitrous oxide reductases [nirS, nirK, and nosZ], dissimilatory sulfite reductases [dsrAB], potential metal reducing C-type cytochromes, and methane monooxygenase [pmoA]) were repeatedly detected. Genes for degradation of MTBE, nitroaromatics and chlorinated compounds were also present, indicating a broad catabolic potential of the treatment unit. FGA’s demonstrated the early establishment of a diverse community with concurrent aerobic and anaerobic processes contributing to the bioremediation process. PMID:16968977

  12. Effect of 0.2% chlorhexidine on microbial and fungal contamination of dental unit waterlines

    PubMed Central

    Agahi, Raha Habib; Hashemipour, Maryam Alsadat; Kalantari, Mahsa; Ayatollah-Mosavi, Amin; Aghassi, Hossein; Nassab, Amir Hossein Gandjalikhan

    2014-01-01

    Background: It is known that dental unit waterline can be a source of infection. The aim of this study was to evaluate the efficacy of a mouthwash, chlorhexidine, in controlling microbial and fungal contamination of dental unit waterlines. Materials and Methods: In the present experimental study, the water in high-speed handpieces and air/water syringes of 35 dental units in a dental school was investigated microbiologically. Five of the units and one tap water served as controls; 100-200-mL water samples were collected aseptically in sterile containers in the morning after a 2-min purge. Water reservoir bottles were emptied and 50 mL of 0.2% chlorhexidine mouthwash was introduced into the tank. Then the water syringe was used to flush the waterline until the pink-colored chlorhexidine was observed to flow from the water syringe. Before the next day's session and before the students used the unit, two water samples from the water syringe and water turbine was collected. The samples were transferred to the laboratory. After 48 h at 37°C, the microbial colonies were counted. The number of these colonies was evaluated using colony forming unit CFU. Data were analyzed with Mann — Whitney U test and SPSS 13.5 statistical program. The statistical significance was defined at P ? 0.05. Results: All 35 units were contaminated before chlorhexidine use; no contamination was detected after adding chlorhexidine to the waterlines of the units. After week 1, 28 of the 30 treated dental unit waterlines (DUWLs) had values of CFU/mL less than 200. Conclusion: The present study showed that the use of chlorhexidine could reduce microbial counts in dental unit waterlines. PMID:25097645

  13. Potential contribution of microbial degradation to natural attenuation of MTBE in surface water systems

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.; Landmeyer, J.E.

    2001-01-01

    To evaluate the potential contribution of in situ biodegradation as a mechanism for natural attenuation of MTBE in surface water, surface water sediments were collected from streams and lakes at 11 sites throughout the US and the ability of the indigenous microorganisms to mineralize [U-14C] MTBE to 14CO2 under aerobic conditions was examined. Mineralization of [U-14C] MTBE to 14CO2 ranged from 15 to 66% over 50 days and did not differ significantly between sediments collected from MTBE contaminated sites and from sites with no history of MTBE exposure. The microorganisms, which inhabit the bed sediments of streams and lakes could degrade MTBE efficiently and this capability is widespread in the environment. Microbial degradation of [U-14C] MTBE was observed in surface-water-sediment microcosms under anaerobic conditions, but the efficiency and products of anaerobic MTBE biodegradation were strongly dependent on the predominant terminal electron accepting conditions. Microorganisms inhabiting the bed sediments of streams and lakes could degrade MTBE effectively under a range of anaerobic terminal electron accepting conditions. Thus, anaerobic bed sediment microbial processes also might contribute to natural attenuation of MTBE in surface water systems throughout the US.

  14. Direct Quantification of Microbial Community Respiration along a Contamination Gradient using a novel Hydrologic Smart Tracer

    NASA Astrophysics Data System (ADS)

    Stanaway, D. J.; Haggerty, R.; Feris, K. P.

    2010-12-01

    Heavy metal contamination in lotic ecosystems is a major health and environmental concern worldwide. The Resazurin Resorufin (Raz Rru) Smart Tracer system (Haggerty et al., 2008) provides a novel approach to test current models of microbial ecosystem response to chronic stressors such as heavy metals. These models predict that functional redundancy of metabolic capabilities of community members (e.g. respiration rate and enzyme activity) will compensate for decreases in species diversity until a stress threshold is reached. At this point, species diversity and function are expected to decline rapidly. Contrary to this model, microbial communities of the Clark Fork River (CF), Montana, demonstrate high levels of species diversity along the contamination gradient, whereas community function is inversely proportional to the level of contamination. The Raz Rru tool, a metabolically reactive hydrologic tracer, allows for direct quantification of in-situ microbial respiration rates. Therefore, this tool provides an opportunity to build upon studies of ecosystem response to contamination previously limited to extrapolation of point scale measurements to reach scale processes. The Raz Rru tool is used here to quantify the magnitude of metal induced limits on heterotrophic microbial respiration in communities that have evolved to different levels of chronic metal exposure. In this way we propose to be able to test a novel hypothesis concerning the nature of evolution of community processes to chronic stress and persistent environmental pollutants. Specifically, we hypothesize that metal contamination produces a measureable metabolic cost to both tolerant and intolerant communities. To test this hypothesis, rates of respiration associated with hyporheic sediments, supporting intact microbial communities, were quantified in the presence and absence of an acute Cd exposure in column experiments. Hyporheic sediment was collected from differently contaminated locations within the CF and compared to sediment from pristine reference sites. The biological reduction rate of Raz to Rru, K_12 in the Advection Dispersion Equation (ADE) below, represents rates of sediment associated heterotrophic respiration. ?C_Raz}/{?t} = {?_L?}/{R} {?^2C_Raz}/{?x^2} - {?}/{R} {?C_Raz}/{?x} - k_1C_Raz -k_12C_Raz [/tex] {?C_Rru}/{?t} = {?_L?}/{R} {?^2C_Rru}/{?x^2} -{?}/{R} {?C_Rru}/{?x} - k_2C_Rru + k_12 {M_Rru}/{M_Raz}CRaz [/tex] The Raz-Rru ADE will be optimized through the Markov Chain Monte Carlo method. Preliminary analysis of Cl^- tracer data provides input estimation of physical parameters, populating the hydrological terms of the ADE necessary for elucidation of K_12. It is expected that sediment metal content and K_12 are inversely related and that acute Cd exposure will negatively affect K_12 of both communities, with communities inhabiting metal contaminated sediments demonstrating a smaller reduction in K_12. This project has the potential to contribute to a revised theory of community response to metal induced chronic ecosystem stress, while contributing to the further development and application of the Raz Rru Smart Tracer system.

  15. Microbial transformations of azaarenes in creosite-contaminated soil and ground water: Laboratory and field studies

    USGS Publications Warehouse

    Pereira, W.E.; Rostad, C.E.; Updegraff, D.M.; Bennett, J.L.

    1988-01-01

    Azaarenes or aromatic nitrogen heterocycles are a class of compounds found in wood-preservative wastes containing creosote. The fate and movement of these compounds in contaminated aquifers is not well understood. Water-quality studies in an aquifer contaminated with creosote near Pensacola, Florida, indicated that ground water was contaminated with several azaarenes and their oxygenated and alkylated derivatives, suggesting that these oxygenated compounds may be products of microbial transformation reactions. Accordingly, laboratory studies were designed to investigate the fate of these compounds. Under aerobic conditions, soil pseudomonads isolated from creosote-contaminated soil converted quinoline to 2(1H)quinoline that subsequently was degraded to unknown products. A methanogenic consortium isolated from an anaerobic sewage digestor, in presence of ground-water and creosote-contaminated soil, converted quinoline, isoquinoline, and 4-methylquinoline to their respective oxygenated analogs. In addition, N-, C-, and O-methylated analogs of oxygenated azaarenes were identified by gas chromatography-mass spectrometry (GC-MS) in aerobic cultures. Under the experimental conditions, 2-methylquinoline was biorefractory. Presence of similar biotransformation products in anaerobic cultures and contaminated ground water from the Pensacola site provided further evidence that these compounds indeed were mivrobial transformation products. Stable isotope labeling studies indicated that the source of the oxygen atom for this hydroxylation reaction under aerobic and anaerobic conditions was water. A mechanism was proposed for this hydroxylation reaction. Whereas parent azaarenes are biodegradable in both anaerobic and aerobic zones, oxygenated and alkylated analogs are more biorefractory and, hence, persistent in anaerobic zones of contaminated aquifers.

  16. EXAMINATION OF GUTTA-PERCHA CONES FOR MICROBIAL CONTAMINATION DURING CHEMICAL USE

    PubMed Central

    Kayaoglu, Guven; Gürel, Mügem; Ömürlü, Hüma; Bek, Zeliha Gonca; Sadik, Burak

    2009-01-01

    Objective: The aim of this study was to evaluate the degree of microbial contamination in packaged gutta-percha cones before and during use in clinical conditions. Material and Methods: Sealed packages of #15-40 gutta-percha cones were opened under aseptic laboratory conditions. Two gutta-percha cones from each size were randomly drawn and added to tubes containing glass beads and 750 ?L of saline. The tubes were vortexed, serially diluted and samples of 250 ?L were cultured on agar plates. The plates were incubated at 37°C for 3 days and colonies were counted. The initially sampled packages were distributed to 12 final year dental students. The packages were collected at the end of the first and the third clinical practice days and sampled as described above. Results: Baseline microbial counts did not exceed 3 CFU. At the end of the first and the third day, additional contamination was found in five and three of the packages, respectively. The ratio of contaminated packages at the first day and the third day was not significantly different (z-test; p > 0.05). The numbers of microorganisms cultured at the first day (8 ± 9.9 CFU) and the third day (4.5 ± 8.3 CFU) were not significantly different (Wilcoxon signed-rank test; p > 0.05). No significant correlation was found between the number of filled root canals and cultured microorganisms at either the first day (Spearman's rho; r = 0.481, p = 0.113) or the third day (r = -0.034, p = 0.917). Conclusions: Gutta-percha cones taken directly from manufacturer's sealed package harbored microorganisms. Clinical use of the packages has been found to be associated with additional contamination of the gutta-percha cones. The counts of cultured microorganisms did not correlate well with the number of filled root canals. PMID:19466260

  17. Dynamics of microbial community composition and function during in-situ bioremediation of a uranium-contaminated aquifer

    Microsoft Academic Search

    J. D. Van Nostrand; L. Wu; W. M. Wu; A. Huang; T. J. Gentry; Y. Deng; J. Carley; S. Carrol; Z. He; B. Gu; J. Luo; C. S. Criddle; D. B. Watson; P. M. Jardine; T. L. Marsh; J. M. Tiedje; T. C. Hazen; J. Zhou

    2010-01-01

    A pilot-scale system was established to examine the feasibility of in situ U(VI) immobilization at a highly contaminated aquifer (U.S. DOE Integrated Field Research Challenge site, Oak Ridge, TN). Ethanol was injected intermittently as an electron donor to stimulate microbial U(VI) reduction, and U(VI) concentrations fell to below the Environmental Protection Agency drinking water standard (0.03 mg liter⁻¹). Microbial communities

  18. Dynamics of Microbial Community Composition and Function during In Situ Bioremediation of a Uranium-Contaminated Aquifer

    Microsoft Academic Search

    Joy D. Van Nostrand; Liyou Wu; Weimin Wu; Zhijian Huang; Terry J Gentry; Ye Deng; Jack M Carley; Sue L Carroll; Zhili He; Baohua Gu; Jian Luo; Craig Criddle; David B Watson; Philip M Jardine; Terence Marsh; James Tiedje; Terry Hazen; Jizhong Zhou

    2011-01-01

    A pilot-scale system was established to examine the feasibility of in situ U(VI) immobilization at a highly contaminated aquifer (U.S. DOE Integrated Field Research Challenge site, Oak Ridge, TN). Ethanol was injected intermittently as an electron donor to stimulate microbial U(VI) reduction, and U(VI) concentrations fell to below the Environmental Protection Agency drinking water standard (0.03 mg liter 1). Microbial

  19. Microbial community analysis in rice paddy soils irrigated by acid mine drainage contaminated water.

    PubMed

    Sun, Min; Xiao, Tangfu; Ning, Zengping; Xiao, Enzong; Sun, Weimin

    2015-03-01

    Five rice paddy soils located in southwest China were selected for geochemical and microbial community analysis. These rice fields were irrigated with river water which was contaminated by Fe-S-rich acid mine drainage. Microbial communities were characterized by high-throughput sequencing, which showed 39 different phyla/groups in these samples. Among these phyla/groups, Proteobacteria was the most abundant phylum in all samples. Chloroflexi, Acidobacteria, Nitrospirae, and Bacteroidetes exhibited higher relative abundances than other phyla. A number of rare and candidate phyla were also detected. Moreover, canonical correspondence analysis suggested that pH, sulfate, and nitrate were significant factors that shaped the microbial community structure. In addition, a wide diversity of Fe- and S-related bacteria, such as GOUTA19, Shewanella, Geobacter, Desulfobacca, Thiobacillus, Desulfobacterium, and Anaeromyxobacter, might be responsible for biogeochemical Fe and S cycles in the tested rice paddy soils. Among the dominant genera, GOUTA19 and Shewanella were seldom detected in rice paddy soils. PMID:25408313

  20. Metagenomic Insights into Evolution of a Heavy Metal-Contaminated Groundwater Microbial Community

    SciTech Connect

    Hemme, Christopher L.; Deng, Ye; Gentry, Terry J.; Fields, Matthew W.; Wu, Liyou; Barua, Soumitra; Barry, Kerrie; Tringe, Susannah G.; Watson, David B.; He, Zhili; Hazen, Terry C.; Tiedje, James M.; Rubin, Edward M.; Zhou, Jizhong

    2010-02-15

    Understanding adaptation of biological communities to environmental change is a central issue in ecology and evolution. Metagenomic analysis of a stressed groundwater microbial community reveals that prolonged exposure to high concentrations of heavy metals, nitric acid and organic solvents (~;;50 years) have resulted in a massive decrease in species and allelic diversity as well as a significant loss of metabolic diversity. Although the surviving microbial community possesses all metabolic pathways necessary for survival and growth in such an extreme environment, its structure is very simple, primarily composed of clonal denitrifying ?- and ?-proteobacterial populations. The resulting community is over-abundant in key genes conferring resistance to specific stresses including nitrate, heavy metals and acetone. Evolutionary analysis indicates that lateral gene transfer could be a key mechanism in rapidly responding and adapting to environmental contamination. The results presented in this study have important implications in understanding, assessing and predicting the impacts of human-induced activities on microbial communities ranging from human health to agriculture to environmental management, and their responses to environmental changes.

  1. Microbial populations related to PAH biodegradation in an aged biostimulated creosote-contaminated soil.

    PubMed

    Lladó, Salvador; Jiménez, Nuria; Viñas, Marc; Solanas, Anna Maria

    2009-09-01

    A previous bioremediation survey on a creosote-contaminated soil showed that aeration and optimal humidity promoted depletion of three-ringed polycyclic aromatic hydrocarbons (PAHs), but residual concentrations of four-ringed benzo(a)anthracene (B(a)A) and chrysene (Chry) remained. In order to explain the lack of further degradation of heavier PAHs such as four-ringed PAHs and to analyze the microbial population responsible for PAH biodegradation, a chemical and microbial molecular approach was used. Using a slurry incubation strategy, soil in liquid mineral medium with and without additional B(a)A and Chry was found to contain a powerful PAH-degrading microbial community that eliminated 89% and 53% of the added B(a)A and Chry, respectively. It is hypothesized that the lack of PAH bioavailability hampered their further biodegradation in the unspiked soil. According to the results of the culture-dependent and independent techniques Mycobacterium parmense, Pseudomonas mexicana, and Sphingobacterials group could control B(a)A and Chry degradation in combination with several microorganisms with secondary metabolic activity. PMID:19153811

  2. Metagenomic insights into evolution of a heavy metal-contaminated groundwater microbial community

    SciTech Connect

    Hemme, Christopher [University of Oklahoma; Deng, Ye [University of Oklahoma; Gentry, Terry [Texas A& M University; Fields, Matthew Wayne [Miami University, Oxford, OH; Wu, Liyou [University of Oklahoma, Norman; Barua, Soumitra [University of Oklahoma; Barry, Kerry [Joint Genome Institute; Green-Tringe, Susannah [Joint Genome Institute, Walnut Creek, California; Watson, David B [ORNL; He, Zhili [University of Oklahoma; Hazen, Terry [Lawrence Berkeley National Laboratory (LBNL); Tiedje, James M. [Michigan State University, East Lansing; Rubin, Edward M. [Joint Genome Institute, Walnut Creek, California; Zhou, Jizhong [University of Oklahoma, Norman

    2010-02-01

    Understanding adaptation of biological communities to environmental change is a central issue in ecology and evolution. Metagenomic analysis of a stressed groundwater microbial community reveals that prolonged exposure to high concentrations of heavy metals, nitric acid and organic solvents (~50 years) has resulted in a massive decrease in species and allelic diversity as well as a significant loss of metabolic diversity. Although the surviving microbial community possesses all metabolic pathways necessary for survival and growth in such an extreme environment, its structure is very simple, primarily composed of clonal denitrifying - and -proteobacterial populations. The resulting community is overabundant in key genes conferring resistance to specific stresses including nitrate, heavy metals and acetone. Evolutionary analysis indicates that lateral gene transfer could have a key function in rapid response and adaptation to environmental contamination. The results presented in this study have important implications in understanding, assessing and predicting the impacts of human-induced activities on microbial communities ranging from human health to agriculture to environmental management, and their responses to environmental changes.

  3. Microbial activity in Alaskan taiga soils contaminated by crude oil in 1976

    SciTech Connect

    Monroe, E.M.; Lindstrom, J.E.; Brown, E.J.; Raddock, J.F. [Univ. of Northern Iowa, Cedar Falls, IA (United States); [Univ. of Alaska, Fairbanks, AK (United States)

    1995-12-31

    Biodegradation, often measured via microbial activity, includes destruction of environmental pollutants by living microorganisms and is dependent upon many physical and chemical factors. Effects of mineral nutrients and organic matter on biodegradation of Prudhoe Bay crude oil were investigated at a nineteen-year-old oil spill site in Alaskan taiga. Microcosms of two different soil types from the spill site; one undeveloped soil with forest litter and detritus (O horizon) and one more developed with lower organic content (A horizon), were treated with various nitrogen and phosphorus amendments, and incubated for up to six weeks. Each microcosm was sampled periodically and assayed for hydrocarbon mineralization potential using radiorespirometry, for total carbon dioxide respired using gas chromatography, and for numbers of hydrocarbon-degrading bacteria and heterotrophic bacteria using most probable number counting techniques. Organic matter in the O horizon soil along with combinations of mineral nutrients were found to stimulate microbial activity. No combination of mineral nutrient additions to the A horizon soil stimulated any of the parameters above those measured in control microcosms. The results of this study indicate that adding mineral nutrients and tilling the O horizon into the A horizon of subarctic soils contaminated with crude oil, would stimulate microbial activity, and therefore the biodegradation potential, ultimately increasing the rate of destruction of crude oil in these soils.

  4. In situ bioremediation of trichloroethylene-contaminated water by a resting-cell methanotrophic microbial filter

    SciTech Connect

    Taylor, R T; Duba, A G; Durham, W B; Hanna, M L; Jackson, K J; Jovanovich, M C; Knapp, R B; Knezovich, J P; Shah, N N; Shonnard, D R; Wijesinghe, A M

    1992-10-01

    The Lawrence Livermore National Laboratory is testing and developing an in situ microbial filter technology for remediating migrating subsurface plumes contaminated with low concentrations of trichloroethylene (TCE). Their current focus is the establishment of a replenishable bioactive zone (catalytic filter) along expanding plume boundaries by the Injection of a representative methanotrophic bacterium, Methylosinus trichosporium OB3b. We have successfully demonstrated this microbial filter strategy using emplaced, attached resting cells (no methane additions) in a 1.1-m flow-through test bed loaded with water-saturated sand. Two separate 24 h pulses of TCE (109 ppb and 85 ppb), one week apart, were pumped through the system at a flow velocity of 1.5 cm/h; no TCE (<0.5 ppb) was detected on the downstream side of the microbial filter. Subsequent excavation of the wet sand confirmed the existence of a TCE-bioactive zone 19 days after it had been created. An enhanced longevity of the cellular, soluble-form methane monooxygenase produced by this methanotroph Is a result of our laboratory bioreactor culturing conditions. Additional experiments with cells in sealed vials and emplaced in the 1.1-m test bed yielded a high resting-cell finite TCE biotransformation capacity of [approximately] 0.25 mg per mg of bacteria; this is suitable for a planned sand-filled trench field demonstration at a Lawrence Livermore National Laboratory site.

  5. The Effects of Microbial Surfaces on Mineral Trapping

    NASA Astrophysics Data System (ADS)

    Ajo-Franklin, C.; Cappuccio, J. A.

    2012-12-01

    Geologic carbon sequestration, the underground storage of CO2, will be an essential component of global climate change mitigation. Carbonate minerals are a stable form of CO2 storage, but their geologic formation is slow. Many microbes are known to affect carbonate mineral formation; however the mechanisms of such mineralization are largely unknown. Suggested mechanisms include metabolic processes that alter pH and supersaturation, as well as cell surface properties that induce mineral nucleation. This work systematically investigates how diverse bacterial surface alter the rates and transformations of calcium carbonate (CaCO3). Under low supersaturation conditions, several diverse species accelerated the formation of CaCO3 relative to silicate containing solutions. These rate changes also occurred for metabolically inactive bacteria, indicating that metabolic activity was not the operating mechanism. Rather, since the number of CaCO3 crystals increased in number as the cell density increased, these results indicate that many bacterial species accelerate the nucleation of CaCO3. Bacterial surface charge and cation binding was assessed using zeta potential measurements and correlated to the bacterial surface chemistry and biomineralization experiments with varying Ca2+ concentrations. To understand the role of specific biomolecules on nucleation, we engineered surface layer proteins (S-layers) to affect their charge and displayed functional groups. From these results combined, we postulate that microbial surfaces can selectively attract Ca2+ ions, serving as nucleation sites for CaCO3, thereby accelerating crystal formation. These observations provide substantive evidence for a non-specific nucleation mechanism, and stress the importance of microbes, on the rate of formation of carbonate minerals. This work also indicates that additional microbial engineering specifically targeted to S-layer proteins could optimize these interactions and be used to implement the sequestration of CO2 as stable mineral carbonates on an accelerated timescale.

  6. Molecular Analysis of Microbial Community Structures in Pristine and Contaminated Aquifers: Field and Laboratory Microcosm Experiments

    PubMed Central

    Shi, Y.; Zwolinski, M. D.; Schreiber, M. E.; Bahr, J. M.; Sewell, G. W.; Hickey, W. J.

    1999-01-01

    This study used phylogenetic probes in hybridization analysis to (i) determine in situ microbial community structures in regions of a shallow sand aquifer that were oxygen depleted and fuel contaminated (FC) or aerobic and noncontaminated (NC) and (ii) examine alterations in microbial community structures resulting from exposure to toluene and/or electron acceptor supplementation (nitrate). The latter objective was addressed by using the NC and FC aquifer materials for anaerobic microcosm studies in which phylogenetic probe analysis was complemented by microbial activity assays. Domain probe analysis of the aquifer samples showed that the communities were predominantly Bacteria; Eucarya and Archaea were not detectable. At the phylum and subclass levels, the FC and NC aquifer material had similar relative abundance distributions of 43 to 65% ?- and ?-Proteobacteria (B+G), 31 to 35% ?-Proteobacteria (ALF), 15 to 18% sulfate-reducing bacteria, and 5 to 10% high G+C gram positive bacteria. Compared to that of the NC region, the community structure of the FC material differed mainly in an increased abundance of B+G relative to that of ALF. The microcosm communities were like those of the field samples in that they were predominantly Bacteria (83 to 101%) and lacked detectable Archaea but differed in that a small fraction (2 to 8%) of Eucarya was detected regardless of the treatment applied. The latter result was hypothesized to reflect enrichment of anaerobic protozoa. Addition of nitrate and/or toluene stimulated microbial activity in the microcosms, but only supplementation of toluene alone significantly altered community structures. For the NC material, the dominant subclass shifted from B+G to ALF, while in the FC microcosms 55 to 65% of the Bacteria community was no longer identifiable by the phylum or subclass probes used. The latter result suggested that toluene exposure fostered the proliferation of phylotype(s) that were otherwise minor constituents of the FC aquifer community. These studies demonstrated that alterations in aquifer microbial communities resulting from specific anthropogenic perturbances can be inferred from microcosm studies integrating chemical and phylogenetic probe analysis and in the case of hydrocarbon contamination may facilitate the identification of organisms important for in situ biodegradation processes. Further work integrating and coordinating microcosm and field experiments is needed to explore how differences in scale, substrate complexity, and other hydrogeological conditions may affect patterns observed in these systems. PMID:10224013

  7. Characterization of the relationship between microbial degradation processes at a hydrocarbon contaminated site using isotopic methods

    NASA Astrophysics Data System (ADS)

    Feisthauer, Stefan; Seidel, Martin; Bombach, Petra; Traube, Sebastian; Knöller, Kay; Wange, Martin; Fachmann, Stefan; Richnow, Hans H.

    2012-05-01

    Decisions to employ monitored natural attenuation (MNA) as a remediation strategy at contaminated field sites require a comprehensive characterization of the site-specific biodegradation processes. In the present study, compound-specific carbon and hydrogen isotope analysis (CSIA) was used to investigate intrinsic biodegradation of benzene and ethylbenzene in an aquifer with high levels of aromatic and aliphatic hydrocarbon contamination. Hydrochemical data and isotope fractionation analysis of sulfate and methane was used complementarily to elucidate microbial degradation processes over the course of a three year period, consisting of six sampling campaigns, in the industrial area of Weißandt-Gölzau (Saxony-Anhalt, Germany). Enrichment of 13C and 2H isotopes in the residual benzene and ethylbenzene pool downgradient from the pollution sources provided evidence of biodegradation of BTEX compounds at this site, targeting both compounds as the key contaminants of concern. The enrichment of heavy sulfur isotopes accompanied by decreasing sulfate concentrations and the accumulation of isotopically light methane suggested that sulfate-reducing and methanogenic processes are the major contributors to overall biodegradation in this aquifer. Along the contaminant plume, the oxidation of methane with ?13CCH4 values of up to + 17.5‰ was detected. This demonstrates that methane formed in the contaminant source can be transported along groundwater flow paths and be oxidized in areas with higher redox potentials, thereby competing directly with the pollutants for electron acceptors. Hydrochemical and isotope data was summarized in a conceptual model to assess whether MNA can be used as viable remediation strategy in Weißandt-Gölzau. The presented results demonstrate the benefits of combining different isotopic methods and hydrochemical approaches to evaluate the fate of organic pollutants in contaminated aquifers.

  8. Comparison of contamination model predictions to LDEF surface measurements

    NASA Astrophysics Data System (ADS)

    Rantanen, Raymond; Gordon, Tim; Finckenor, Miria M.; Pippin, Harold G.

    1998-10-01

    Contaminant deposition measurement have been made on species content and depth profiles on three experiment trays from the long duration exposure facility (LDEF), Auger, Argon sputtering, ESCA and SEM analysis was used to define the contaminant deposits. The Integrated Spacecraft Environments Model (ISEM) was used to predict the deposition levels of the contaminants measured on the three trays. The details of the modeling and the assumptions use dare presented along with the predictions for the deposition on select surfaces on the trays. These are compared to the measured results. The trays represents surfaces that have a high atomic oxygen flux, an intermediate oxygen flux, and no oxygen flux. All surfaces received significant solar UV flux. It appears that the atomic oxygen is necessary for significant deposition to occur. Surfaces that saw significant contaminant flux, solar UV and no atomic oxygen did not show any appreciable levels of observable deposition. The implications of the atomic oxygen interaction with contaminant deposits from silicon contaminant sources is discussed. The primary contaminant sources in the LDEF analysis are DC6-1104 adhesive and Z-306 paint. The result and interpretation of the findings have a potential significant impact on spacecraft surfaces that are exposed to solar UV and atomic oxygen in low Earth orbit.

  9. TRACE ORGANIC CONTAMINANTS IN ANTHROPOGENICALLY ACIDIFIED SURFACE WATERS

    EPA Science Inventory

    The biological effects of trace organic contaminants in anthropogenically acidified surface waters are mediated by the nature of the association of trace organics with dissolved and particulate organic matter (DOC and POC). his paper (1) briefly reviews available deposition estim...

  10. Physicochemical and biological quality of soil in hexavalent chromium-contaminated soils as affected by chemical and microbial remediation.

    PubMed

    Liao, Yingping; Min, Xiaobo; Yang, Zhihui; Chai, Liyuan; Zhang, Shujuan; Wang, Yangyang

    2014-01-01

    Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different remediation technologies have been applied. In this paper, microbial remediation with indigenous bacteria and chemical remediation with ferrous sulphate were used for the remediation of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg(-1)) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg(-1). Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The result showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contaminated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitoring the quality change in chromium-contaminated soils. PMID:23784058

  11. Quantification of Microbial Activities in Near-Surface Soils

    NASA Astrophysics Data System (ADS)

    Schroth, M. H.; Nauer, P.; Zeyer, J.

    2007-12-01

    Microbial processes in near-surface soils play an important role in carbon and nutrient cycling, and specifically in the turnover of greenhouse gases such as CO2 and CH4. We modified a recently developed technique, the gas push-pull test (GPPT), to allow for the in-situ quantification of microbial activities in near-surface soils. A GPPT consists of the controlled injection of a gas mixture containing reactive gases (e.g., CH4, O2, CO2) and nonreactive tracer gases (e.g., Ar, Ne) into the soil, followed by the extraction of the gas mixture/soil-air blend from the same location. Rates of microbial activities are computed from the gases" breakthrough curves obtained during the GPPT's extraction phase. For a GPPT to be applied successfully, it is important that sufficient mass of the injected gases can be recovered during the test, even after prolonged incubation in soil. But this may be difficult to achieve during GPPTs performed in near- surface soils, where gas loss to the atmosphere can be substantial. Our modification consisted of performing GPPTs within a steel cylinder (8.4-cm radius), which was previously driven into the soil to a depth of 50 cm. During the GPPTs, the cylinder was temporarily closed with a removable lid to minimize gas loss to the atmosphere. We performed a series of numerical simulations as well as laboratory experiments to test the usefulness of this modification. Numerical simulations confirmed that without use of the cylinder, typical near- surface GPPTs (e.g., injection/extraction depth 20 cm below soil surface) are subject to extensive gas loss to the atmosphere (mass recovery < 20% for most gases), whereas mass recovery of injected gases increased dramatically when the cylinder was employed (mass recovery > 90% for most gases). Results from laboratory experiments confirmed this observation. We will also present results of a first field application, in which a near- surface GPPT was successfully conducted in a sandy soil to quantify in-situ rates of CH4 oxidation.

  12. Microbial cycling of mercury in contaminated pelagic and wetland sediments of San Pablo Bay, California

    Microsoft Academic Search

    M. C. Marvin-DiPasquale; J. L. Agee; R. M. Bouse; B. E. Jaffe

    2003-01-01

    San Pablo Bay is an estuary, within northern San Francisco Bay, containing elevated sediment mercury (Hg) levels because of historic loading of hydraulic mining debris during the California gold-rush of the late 1800s. A preliminary investigation of benthic microbial Hg cycling was conducted in surface sediment (0-4 cm) collected from one salt-marsh and three open-water sites. A deeper profile (0-26

  13. Surface contamination and corrosion in pyrotechnic actuators

    Microsoft Academic Search

    R. G. Jungst; R. K. Quinn; T. M. Massis; R. N. Roberts; R. E. Whan

    1978-01-01

    Accelerated aging studies of pyrotechnic actuators containing a mixture of titanium and potassium perchlorate powders have revealed that extensive corrosion of the metal pins and bridgewires used to ignite the device occurs in relatively short times. Analyses show that the corrosive process is associated with chlorine and organic contaminants, the primary sources of which are residual cutting oils, chlorinated cleaning

  14. CONTAMINANT DETECTION ON POULTRY CARCASS SURFACES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A real-time imaging system has been developed to detect fecal contaminants on poultry carcasses. The system, which will require two to three multispectral cameras to fully image the outside of a poultry carcass, has shown promise in early trials. The system was developed from spectroscopic first p...

  15. Assessment of surface contamination with contact mechanics

    Microsoft Academic Search

    JOHN A. EMERSON; GREGORY V. MILLER; CHRISTOPHER R. SORENSEN; RAYMOND A. PEARSON

    2000-01-01

    The authors are particularly interested in the work of adhesion measurements as a means to facilitate the understanding of the adhesive failure mechanisms for systems containing encapsulated and bonded components. Of the several issues under investigation, one is the effect of organic contamination on the adhesive strength for several types of polymer\\/metal interface combinations. The specific question that the authors

  16. Organic surface film contamination of Vitallium implants.

    PubMed

    Carter, J M; Flynn, H E; Meenaghan, M A; Natiella, J R; Akers, C K; Baier, R E

    1981-11-01

    Conventional finishing and polishing techniques used to prepare Vitallium subperiosteal dental implant castings were found to produce low energy surfaces as measured by critical surface tension. Standard metallographic preparation gave slightly higher values. Glow discharge cleaning of both types of polished surface gave much higher critical surface tension values. This suggests the presence of an organic film after surface polishing of the implant which may later affect tissue reaction, in particular attachment, as has been noticed in related animal studies. PMID:7309766

  17. Inhibition and enhancement of microbial surface colonization: the role of silicate composition

    E-print Network

    Roberts, Jennifer A.

    Inhibition and enhancement of microbial surface colonization: the role of silicate composition and surfaces. Results from in situ colonization studies in an anaerobic groundwater at pH 6.8 combined dominate microbial colonization on positively charged oxide surfaces regardless of mineral composition

  18. Total effective dose equivalent associated with fixed uranium surface contamination

    SciTech Connect

    Bogard, J.S.; Hamm, R.N.; Ashley, J.C.; Turner, J.E.; England, C.A.; Swenson, D.E.; Brown, K.S.

    1997-04-01

    This report provides the technical basis for establishing a uranium fixed-contamination action level, a fixed uranium surface contamination level exceeding the total radioactivity values of Appendix D of Title 10, Code of Federal Regulations, part 835 (10CFR835), but below which the monitoring, posting, and control requirements for Radiological Areas are not required for the area of the contamination. An area of fixed uranium contamination between 1,000 dpm/100 cm{sup 2} and that level corresponding to an annual total effective dose equivalent (TEDE) of 100 mrem requires only routine monitoring, posting to alert personnel of the contamination, and administrative control. The more extensive requirements for monitoring, posting, and control designated by 10CFR835 for Radiological Areas do not have to be applied for these intermediate fixed-contamination levels.

  19. Use of Bacteroidales Microbial Source Tracking To Monitor Fecal Contamination in Fresh Produce Production

    PubMed Central

    Ravaliya, Kruti; Garcia, Santos; Heredia, Norma; Fabiszewski de Aceituno, Anna; Bartz, Faith E.; Leon, Juan S.; Jaykus, Lee-Ann

    2014-01-01

    In recent decades, fresh and minimally processed produce items have been associated with an increasing proportion of food-borne illnesses. Most pathogens associated with fresh produce are enteric (fecal) in origin, and contamination can occur anywhere along the farm-to-fork chain. Microbial source tracking (MST) is a tool developed in the environmental microbiology field to identify and quantify the dominant source(s) of fecal contamination. This study investigated the utility of an MST method based on Bacteroidales 16S rRNA gene sequences as a means of identifying potential fecal contamination, and its source, in the fresh produce production environment. The method was applied to rinses of fresh produce, source and irrigation waters, and harvester hand rinses collected over the course of 1 year from nine farms (growing tomatoes, jalapeño peppers, and cantaloupe) in Northern Mexico. Of 174 samples, 39% were positive for a universal Bacteroidales marker (AllBac), including 66% of samples from cantaloupe farms (3.6 log10 genome equivalence copies [GEC]/100 ml), 31% of samples from tomato farms (1.7 log10 GEC/100 ml), and 18% of samples from jalapeño farms (1.5 log10 GEC/100 ml). Of 68 AllBac-positive samples, 46% were positive for one of three human-specific markers, and none were positive for a bovine-specific marker. There was no statistically significant correlation between Bacteroidales and generic Escherichia coli across all samples. This study provides evidence that Bacteroidales markers may serve as alternative indicators for fecal contamination in fresh produce production, allowing for determination of both general contamination and that derived from the human host. PMID:24212583

  20. Automatic Measurement of Low Level Contamination on Concrete Surfaces

    SciTech Connect

    Tachibana, M.; Itoh, H.; Shimada, T.; Yanagihara, S.

    2002-02-28

    Automatic measurement of radioactivity is necessary for considering cost effectiveness in final radiological survey of building structures in decommissioning nuclear facilities. The RAPID (radiation measuring pilot device for surface contamination) was developed to be applied to automatic measurement of low level contamination on concrete surfaces. The RAPID has a capability to measure contamination with detection limit of 0.14 Bq/cm2 for 60Co in 30 seconds of measurement time and its efficiency is evaluated to be 5 m2/h in a normal measurement option. It was confirmed that low level contamination on concrete surfaces could be surveyed by the RAPID efficiently compared with direct measurement by workers through its actual application.

  1. Radon induced surface contaminations in low background experiments

    SciTech Connect

    Pattavina, L. [INFN - Laboratori Nazionali del Gran Sasso, I-67010 Assergi (AQ) (Italy)] [INFN - Laboratori Nazionali del Gran Sasso, I-67010 Assergi (AQ) (Italy)

    2013-08-08

    In neutrinoless double-beta decay and dark matter searches, one of the main issues is to increase the experimental sensitivity through careful material selection and production, minimizing the background contributions. In order to achieve the required, extremely low, counting rates, very stringent requirements must be fulfilled in terms of bulk material radiopurity. As the experimental sensitivity increases, the bulk impurities in the detector components decrease, and surface contaminations start to play an increasingly significant role In fully active detectors, like cryogenic particle detectors, surface contaminations are a critical issue (as shown by the CUORICINO experiment). {sup 222}Rn is by far the most intense source of airborne radioactivity, and if a radio-pure material is exposed to environment where the Radon concentration is not minimized, {sup 210}Pb and {sup 210}Po contaminations can occur. The mechanisms and the dynamics of Radon-induced surface contaminations are reviewed, and specific solutions to prevent and to reject the induced background are presented.

  2. LASER CLEANING OF CONTAMINATED PAINTED SURFACES

    SciTech Connect

    Ames A. Grisanti; Charlene R. Crocker; Robert R. Jensen

    1999-11-19

    Several techniques are available or under development for surface decontamination in nuclear facilities. Each technique has its merits; however, none of them is universally the best choice for all surface decontamination applications. Because of the multitude of factors which influence the environmental and economic aspects of selecting a surface decontamination technique, it is difficult to select the best method in a given situation; an objective basis for comparing techniques is needed. The objective of this project was to develop a software tool for use by personnel selecting a surface decontamination technique. The software incorporates performance data for available surface decontamination techniques. The beta release version of the Surface Decontamination Assistant Software has been completed and has undergone testing at the Energy and Environmental Research Center. Minor modifications to the software were completed, and a final release version of the software is ready to be issued.

  3. Plant tolerance to diesel minimizes its impact on soil microbial characteristics during rhizoremediation of diesel-contaminated soils.

    PubMed

    Barrutia, O; Garbisu, C; Epelde, L; Sampedro, M C; Goicolea, M A; Becerril, J M

    2011-09-01

    Soil contamination due to petroleum-derived products is an important environmental problem. We assessed the impacts of diesel oil on plants (Trifolium repens and Lolium perenne) and soil microbial community characteristics within the context of the rhizoremediation of contaminated soils. For this purpose, a diesel fuel spill on a grassland soil was simulated under pot conditions at a dose of 12,000 mg diesel kg(-1) DW soil. Thirty days after diesel addition, T. repens (white clover) and L. perenne (perennial ryegrass) were sown in the pots and grown under greenhouse conditions (temperature 25/18 °C day/night, relative humidity 60/80% day/night and a photosynthetic photon flux density of 400 ?mol photon m(-2) s(-1)) for 5 months. A parallel set of unplanted pots was also included. Concentrations of n-alkanes in soil were determined as an indicator of diesel degradation. Seedling germination, plant growth, maximal photochemical efficiency of photosystem II (F(v)/F(m)), pigment composition and lipophylic antioxidant content were determined to assess the impacts of diesel on the studied plants. Soil microbial community characteristics, such as enzyme and community-level physiological profiles, were also determined and used to calculate the soil quality index (SQI). The presence of plants had a stimulatory effect on soil microbial activity. L. perenne was far more tolerant to diesel contamination than T. repens. Diesel contamination affected soil microbial characteristics, although its impact was less pronounced in the rhizosphere of L. perenne. Rhizoremediation with T. repens and L. perenne resulted in a similar reduction of total n-alkanes concentration. However, values of the soil microbial parameters and the SQI showed that the more tolerant species (L. perenne) was able to better maintain its rhizosphere characteristics when growing in diesel-contaminated soil, suggesting a better soil health. We concluded that plant tolerance is of crucial importance for the recovery of soil health during rhizoremediation of contaminated soils. PMID:21741073

  4. Comparative evaluation of the indigenous microbial diversity vs. drilling fluid contaminants in the NEEM Greenland ice core.

    PubMed

    Miteva, Vanya; Burlingame, Caroline; Sowers, Todd; Brenchley, Jean

    2014-08-01

    Demonstrating that the detected microbial diversity in nonaseptically drilled deep ice cores is truly indigenous is challenging because of potential contamination with exogenous microbial cells. The NEEM Greenland ice core project provided a first-time opportunity to determine the origin and extent of contamination throughout drilling. We performed multiple parallel cultivation and culture-independent analyses of five decontaminated ice core samples from different depths (100-2051 m), the drilling fluid and its components Estisol and Coasol, and the drilling chips collected during drilling. We created a collection of diverse bacterial and fungal isolates (84 from the drilling fluid and its components, 45 from decontaminated ice, and 66 from drilling chips). Their categorization as contaminants or intrinsic glacial ice microorganisms was based on several criteria, including phylogenetic analyses, genomic fingerprinting, phenotypic characteristics, and presence in drilling fluid, chips, and/or ice. Firmicutes and fungi comprised the dominant group of contaminants among isolates and cloned rRNA genes. Conversely, most Proteobacteria and Actinobacteria originating from the ice were identified as intrinsic. This study provides a database of potential contaminants useful for future studies of NEEM cores and can contribute toward developing standardized protocols for contamination detection and ensuring the authenticity of the microbial diversity in deep glacial ice. PMID:24450335

  5. Laser removal of loose uranium compound contamination from metal surfaces

    NASA Astrophysics Data System (ADS)

    Roberts, D. E.; Modise, T. S.

    2007-04-01

    Pulsed laser removal of surface contamination of uranyl nitrate and uranium dioxide from stainless steel has been studied. Most of the loosely bound contamination has been removed at fluence levels below 0.5 J cm -2, leaving about 5% fixed contamination for uranyl nitrate and 15% for uranium dioxide. Both alpha and beta activities are then sufficiently low that contaminated objects can be taken out of a restricted radiation area for re-use. The ratio of beta to alpha activity is found to be a function of particle size and changes during laser removal. In a separate experiment using technetium-99m, the collection of removed radioactivity in the filter was studied and an inventory made of removed and collected contamination.

  6. Microbial contamination detection in water resources: interest of current optical methods, trends and needs in the context of climate change.

    PubMed

    Jung, Aude-Valérie; Le Cann, Pierre; Roig, Benoit; Thomas, Olivier; Baurès, Estelle; Thomas, Marie-Florence

    2014-04-01

    Microbial pollution in aquatic environments is one of the crucial issues with regard to the sanitary state of water bodies used for drinking water supply, recreational activities and harvesting seafood due to a potential contamination by pathogenic bacteria, protozoa or viruses. To address this risk, microbial contamination monitoring is usually assessed by turbidity measurements performed at drinking water plants. Some recent studies have shown significant correlations of microbial contamination with the risk of endemic gastroenteresis. However the relevance of turbidimetry may be limited since the presence of colloids in water creates interferences with the nephelometric response. Thus there is a need for a more relevant, simple and fast indicator for microbial contamination detection in water, especially in the perspective of climate change with the increase of heavy rainfall events. This review focuses on the one hand on sources, fate and behavior of microorganisms in water and factors influencing pathogens' presence, transportation and mobilization, and on the second hand, on the existing optical methods used for monitoring microbiological risks. Finally, this paper proposes new ways of research. PMID:24747537

  7. MOLECULAR PROFILING OF MICROBIAL COMMUNITIES FROM CONTAMINATED SOURCES: USE OF SUBTRACTIVE CLONING METHODS AND RDNA SPACER SEQUENCES

    EPA Science Inventory

    This research addresses the development and testing of molecular methods that will allow rapid characterization of microbial communities in perturbed or contaminated ecosystems. The major objective of the research is to provide appropriate sequences and to assemble a high-density...

  8. A preliminary evaluation of the use of microbial culture filtrates for the control of contaminants in plant tissue culture systems

    Microsoft Academic Search

    S. Hussain; D. N. Price

    1994-01-01

    The culture extracts of 21 micro-organisms were screened in vitro for anti-microbial activity against a range of test contaminants isolated from plant tissue cultures. Extracts produced by Trichoderma viride Pers. (strain A) and Bacillus subtilis Ehrenberg (strain 2) had the highest antifungal activity and extracts from Pseudomonas fluorescens Migula (strain X) had the highest antibacterial activity. When extracts of these

  9. Changes in Microbial Biomass Parameters of a Heavy Metal-Contaminated Calcareous Soil during a Field Remediation Experiment

    Microsoft Academic Search

    R. Clemente; C. de la Fuente; R. Moral; M. P. Bernal

    2007-01-01

    Soil microbial biomass parameters give useful information about the restoration degree and quality of contaminated soils. These pa- rameters were studied in a field experiment where the effect of two organic amendments on the bioavailability of heavy metals in an agri- cultural soil and on their accumulation in Beta vulgaris and Beta maritima was assessed. The soil was a calcareous

  10. Environmental Whole-Genome Amplification To Access Microbial Populations in Contaminated Sediments

    PubMed Central

    Abulencia, Carl B.; Wyborski, Denise L.; Garcia, Joseph A.; Podar, Mircea; Chen, Wenqiong; Chang, Sherman H.; Chang, Hwai W.; Watson, David; Brodie, Eoin L.; Hazen, Terry C.; Keller, Martin

    2006-01-01

    Low-biomass samples from nitrate and heavy metal contaminated soils yield DNA amounts that have limited use for direct, native analysis and screening. Multiple displacement amplification (MDA) using ?29 DNA polymerase was used to amplify whole genomes from environmental, contaminated, subsurface sediments. By first amplifying the genomic DNA (gDNA), biodiversity analysis and gDNA library construction of microbes found in contaminated soils were made possible. The MDA method was validated by analyzing amplified genome coverage from approximately five Escherichia coli cells, resulting in 99.2% genome coverage. The method was further validated by confirming overall representative species coverage and also an amplification bias when amplifying from a mix of eight known bacterial strains. We extracted DNA from samples with extremely low cell densities from a U.S. Department of Energy contaminated site. After amplification, small-subunit rRNA analysis revealed relatively even distribution of species across several major phyla. Clone libraries were constructed from the amplified gDNA, and a small subset of clones was used for shotgun sequencing. BLAST analysis of the library clone sequences showed that 64.9% of the sequences had significant similarities to known proteins, and “clusters of orthologous groups” (COG) analysis revealed that more than half of the sequences from each library contained sequence similarity to known proteins. The libraries can be readily screened for native genes or any target of interest. Whole-genome amplification of metagenomic DNA from very minute microbial sources, while introducing an amplification bias, will allow access to genomic information that was not previously accessible. PMID:16672469

  11. Environmental Whole-Genome Amplification to Access Microbial Diversity in Contaminated Sediments

    SciTech Connect

    Abulencia, C.B.; Wyborski, D.L.; Garcia, J.; Podar, M.; Chen, W.; Chang, S.H.; Chang, H.W.; Watson, D.; Brodie,E.I.; Hazen, T.C.; Keller, M.

    2005-12-10

    Low-biomass samples from nitrate and heavy metal contaminated soils yield DNA amounts that have limited use for direct, native analysis and screening. Multiple displacement amplification (MDA) using ?29 DNA polymerase was used to amplify whole genomes from environmental, contaminated, subsurface sediments. By first amplifying the genomic DNA (gDNA), biodiversity analysis and gDNA library construction of microbes found in contaminated soils were made possible. The MDA method was validated by analyzing amplified genome coverage from approximately five Escherichia coli cells, resulting in 99.2 percent genome coverage. The method was further validated by confirming overall representative species coverage and also an amplification bias when amplifying from a mix of eight known bacterial strains. We extracted DNA from samples with extremely low cell densities from a U.S. Department of Energy contaminated site. After amplification, small subunit rRNA analysis revealed relatively even distribution of species across several major phyla. Clone libraries were constructed from the amplified gDNA, and a small subset of clones was used for shotgun sequencing. BLAST analysis of the library clone sequences showed that 64.9 percent of the sequences had significant similarities to known proteins, and ''clusters of orthologous groups'' (COG) analysis revealed that more than half of the sequences from each library contained sequence similarity to known proteins. The libraries can be readily screened for native genes or any target of interest. Whole-genome amplification of metagenomic DNA from very minute microbial sources, while introducing an amplification bias, will allow access to genomic information that was not previously accessible.

  12. Characterization of microbial and metal contamination in flooded New York City neighborhoods following Superstorm Sandy

    NASA Astrophysics Data System (ADS)

    Dueker, M.; O'Mullan, G. D.; Sahajpal, R.

    2013-12-01

    Large scale flooding of waterfront neighborhoods occurred in New York City (NYC) during Superstorm Sandy. While NYC waterways commonly experience combined sewer overflow (CSO) and associated water quality degradation during rain storms, Superstorm Sandy was unique in that these potentially contaminated waters were transported over the banks and into city streets and buildings. Sampling of waterways, storm debris on city streets, and flood water trapped in building basements occurred in the days following Sandy, including in neighborhoods bordering the Gowanus Canal and Newtown Creek, which are both Superfund sites known to frequently contain high levels of sewage associated bacteria and metal contamination. Samples enumerated for the sewage indicating bacterium, Enterococcus, suggest that well-flushed waterways recovered quickly from sewage contamination in the days following the storm, with Enterococci concentrations similar to background levels measured before flooding occurred. In contrast, storm debris on city streets and waters from flooded basements had much higher levels of sewage-associated bacteria days after flooding occurred. Analysis of 180,000 bacterial 16S rRNA gene sequences obtained from flood water samples and flood debris confirmed the presence of bacterial genera often associated with sewage impacted samples (e.g. Escherichia, Streptococcus, Clostridium, Trichococcus, Aeromonas) and a community composition similar to CSO discharge. Elemental analysis suggests low levels of metal contamination in most flood water, but much higher levels of Cu, Pb, and Cr were found in leach from some storm debris samples found adjacent to the Newtown Creek and Gowanus Canal superfund sites. These data suggest a rapid recovery of water quality in local waterways after Superstorm Sandy, but that trapped flood water and debris samples in urban neighborhoods retained elevated levels of microbial sewage pollution, and in some cases metal pollution, days after that waterway recovery. These findings indicate a potentially significant risk to local populations exposed to trapped flood waters and debris in the aftermath of urban waterway flooding events.

  13. Biodegradation of phenanthrene using adapted microbial consortium isolated from petrochemical contaminated environment.

    PubMed

    Janbandhu, Anjali; Fulekar, M H

    2011-03-15

    In developing countries like India, there are many industrial areas discharging effluent containing large amount of polyaromatic hydrocarbon (PAH) which causes hazardous effect on the soil-water environment. The objective of this study was to isolate and characterize high-efficiency PAH-degrading microbial consortium from 3 decade old petrochemical refinery field located in Nagpur, Maharashtra with history of PAH disposal. Based on biochemical tests and 16S rDNA gene sequence analysis the consortium was identified as Sphingobacterium sp., Bacillus cereus and a novel bacterium Achromobacter insolitus MHF ENV IV with effective phenanthrene-degrading ability. The biodegradation data of phenanthrene indicates about 100%, 56.9% and 25.8% degradation at the concentration of 100mg/l, 250 mg/l and 500 mg/l respectively within 14 days. The consortium and its monoculture isolates also utilized variety of other hydrocarbons for growth. To best of our knowledge this is the first time that Achromobacter insolitus has been reported to mineralize phenanthrene effectively. GC-MS analysis of phenanthrene degradation confirmed biodegradation by detection of intermediates like salicylaldehyde, salicylic acid and catechol. All the results indicated that the microbial consortium have a promising application in bioremediation of petrochemical contaminated environments and could be potentially useful for the study of PAH degradation and for bioremediation purposes. PMID:21281999

  14. Benzoate-driven dehalogenation of chlorinated ethenes in microbial cultures from a contaminated aquifer.

    PubMed

    Bunge, Michael; Kleikemper, Jutta; Miniaci, Ciro; Duc, Laurence; Muusse, Margje G; Hause, Gerd; Zeyer, Josef

    2007-10-01

    Microbial dehalogenation of tetrachloroethene (PCE) and cis-dichloroethene (cis-DCE) was studied in cultures from a continuous stirred tank reactor initially inoculated with aquifer material from a PCE-contaminated site. Cultures amended with hydrogen and acetate readily dechlorinated PCE and cis-DCE; however, this transformation was incomplete and resulted in the accumulation of chlorinated intermediates and only small amounts of ethene within 60 days of incubation. Conversely, microbial PCE and cis-DCE dechlorination in cultures with benzoate and acetate resulted in the complete transformation to ethene within 30 days. Community fingerprinting by denaturing gradient gel electrophoresis (DGGE) revealed the predominance of phylotypes closely affiliated with Desulfitobacterium, Dehalococcoides, and Syntrophus species. The Dehalococcoides culture VZ, obtained from small whitish colonies in cis-DCE dechlorinating agarose cultures, revealed an irregular cell diameter between 200 and 500 nm, and a spherical or biconcave disk-shaped morphology. These organisms were identified as responsible for the dechlorination of cis-DCE to ethene in the PCE-dechlorinating consortia, operating together with the Desulfitobacterium as PCE-to-cis-DCE dehalogenating bacterium and with a Syntrophus species as potential hydrogen-producing partner in cultures with benzoate. PMID:17768618

  15. Effects of the contamination environment on surfaces and materials

    NASA Technical Reports Server (NTRS)

    Maag, Carl R.

    1989-01-01

    In addition to the issues that have always existed, demands are being placed on space systems for increased contamination prevention/control. Optical surveillance sensors are required to detect low radiance targets. This increases the need for very low scatter surfaces in the optical system. Particulate contamination levels typically experienced in today's working environments/habits will most likely compromise these sensors. Contamination (molecular and particulate) can also affect the survivability of space sensors in both the natural and hostile space environments. The effects of di-octyl phthalate (DOP) on sensors are discussed.

  16. Microbial community response to petroleum hydrocarbon contamination in the unsaturated zone at the experimental field site Vaerløse, Denmark.

    PubMed

    Kaufmann, Karin; Christophersen, Mette; Buttler, Alexandre; Harms, Hauke; Höhener, Patrick

    2004-06-01

    This study investigates the influence of petroleum hydrocarbons on a microbial community in the vadose zone under field conditions. An artificial hydrocarbon mixture consisting of volatile and semi-volatile compounds similar to jet-fuel was emplaced in a previously uncontaminated vadose zone in nutrient-poor glacial melt water sand. The experiment included monitoring of microbial parameters and CO(2) concentrations in soil gas over 3 months in and outside the hydrocarbon vapor plume that formed around the buried petroleum. Microbial and chemical analyses of soil and vadose zone samples were performed on samples from cores drilled to 3.3 m depth on three dates and three lateral distances from the buried petroleum mass. Significantly elevated CO(2) concentrations were observed after contamination. Total cell numbers as determined by fluorescence microscopy were strongly correlated with soil organic carbon and nitrogen content but varied little with contamination. Redundancy analysis (RDA) allowed direct analysis of effects of selected environmental variables or the artificial contamination on microbiological parameters. Variation in biomass and CO(2) production was explained by soil parameters, to 46%, and by the duration of contamination, to 39.8%. The microbial community structure was assessed by community level physiological profiles (CLPP) analysis using Biolog(TM) Eco-Plates. In the CLPP data only 35.9% of the variation could be linked to soil parameters and contamination, however, the samples with greatest exposure to hydrocarbons grouped together on RDA plots. It is concluded that, at this nutrient-poor site, the microbial community was dominated by natural heterogeneity and that the influence of petroleum hydrocarbon vapors was weak. PMID:19712308

  17. Influence of diesel contamination on the benthic microbial/meiofaunal food web of a Louisiana salt marsh

    SciTech Connect

    Carman, K.R.; Fleeger, J.W.; Pomarico, S. [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Zoology

    1994-12-31

    The authors studied the influence of diesel-contaminated sediments on the benthic microbial/meiofaunal food web from a Louisiana salt marsh. Diesel-contaminated sediment was added to microcosms (intact cores of marsh mud) in a range of doses, and a suite of microbial and meiofaunal responses were measured over a 28-day period. The authors measured bacterial and microalgal (Chl a) abundance, bacterial and microalgal activity using radiotracers ({sup 14}C-acetate and {sup 14}CO{sub 2}, respectively), meiofaunal grazing on microalgae, meiofaunal community structure, and meiofaunal physiological condition. Preliminary results indicate that diesel-contaminated sediments influence microalgal biomass and activity, as well as the life histories of benthic copepod species.

  18. Atomic Force Microscopy in Microbiology: New Structural and Functional Insights into the Microbial Cell Surface

    PubMed Central

    2014-01-01

    ABSTRACT Microbial cells sense and respond to their environment using their surface constituents. Therefore, understanding the assembly and biophysical properties of cell surface molecules is an important research topic. With its ability to observe living microbial cells at nanometer resolution and to manipulate single-cell surface molecules, atomic force microscopy (AFM) has emerged as a powerful tool in microbiology. Here, we survey major breakthroughs made in cell surface microbiology using AFM techniques, emphasizing the most recent structural and functional insights. PMID:25053785

  19. Characterization of the Cell Surface Properties of Drinking Water Pathogens by Microbial Adhesion to Hydrocarbon and Electrophoretic Mobility Measurements

    EPA Science Inventory

    The surface characteristics of microbial cells directly influence their mobility and behavior within aqueous environments. The cell surface hydrophobicity (CSH) and electrophoretic mobility (EPM) of microbial cells impact a number of interactions and processes including aggregati...

  20. Antineoplastic drugs contamination of workplace surfaces in two Portuguese hospitals.

    PubMed

    Viegas, Susana; Pádua, Mário; Veiga, Ana Costa; Carolino, Elisabete; Gomes, Mário

    2014-11-01

    Despite the classification as known or suspected human carcinogens, by the International Agency for Research on Cancer, the antineoplastic drugs are extensively used in cancer treatment due to their specificity and efficacy. As human carcinogens, these drugs represent a serious threat to the healthcare workers involved in their preparation and administration. This work aims to contribute to better characterize the occupational exposure of healthcare professionals to antineoplastic drugs, by assessing workplace surfaces contamination of pharmacy and administration units of two Portuguese hospitals. Surface contamination was assessed by the determination of cyclophosphamide, 5-fluorouracil, and paclitaxel. These three drugs were used as surrogate markers for surfaces contamination by cytotoxic drugs. Wipe samples were taken and analyzed by HPLC-DAD. From the total of 327 analyzed samples, in 121 (37 %) was possible to detect and quantify at least one drug. Additionally, 28 samples (8.6 %) indicate contamination by more than one antineoplastic drug, mainly in the administration unit, in both hospitals. Considering the findings in both hospitals, specific measures should be taken, particularly those related with the promotion of good practices and safety procedures and also routine monitoring of surfaces contamination in order to guarantee the appliance of safety measures. PMID:25096642

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

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

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

  2. Development of surrogate correlation models to predict trace organic contaminant oxidation and microbial inactivation during ozonation.

    PubMed

    Gerrity, Daniel; Gamage, Sujanie; Jones, Darryl; Korshin, Gregory V; Lee, Yunho; Pisarenko, Aleksey; Trenholm, Rebecca A; von Gunten, Urs; Wert, Eric C; Snyder, Shane A

    2012-12-01

    The performance of ozonation in wastewater depends on water quality and the ability to form hydroxyl radicals (·OH) to meet disinfection or contaminant transformation objectives. Since there are no on-line methods to assess ozone and ·OH exposure in wastewater, many agencies are now embracing indicator frameworks and surrogate monitoring for regulatory compliance. Two of the most promising surrogate parameters for ozone-based treatment of secondary and tertiary wastewater effluents are differential UV(254) absorbance (?UV(254)) and total fluorescence (?TF). In the current study, empirical correlations for ?UV(254) and ?TF were developed for the oxidation of 18 trace organic contaminants (TOrCs), including 1,4-dioxane, atenolol, atrazine, bisphenol A, carbamazepine, diclofenac, gemfibrozil, ibuprofen, meprobamate, naproxen, N,N-diethyl-meta-toluamide (DEET), para-chlorobenzoic acid (pCBA), phenytoin, primidone, sulfamethoxazole, triclosan, trimethoprim, and tris-(2-chloroethyl)-phosphate (TCEP) (R(2) = 0.50-0.83) and the inactivation of three microbial surrogates, including Escherichia coli, MS2, and Bacillus subtilis spores (R(2) = 0.46-0.78). Nine wastewaters were tested in laboratory systems, and eight wastewaters were evaluated at pilot- and full-scale. A predictive model for OH exposure based on ?UV(254) or ?TF was also proposed. PMID:23062789

  3. Can Volatile Organic Metabolites Be Used to Simultaneously Assess Microbial and Mite Contamination Level in Cereal Grains and Coffee Beans?

    PubMed Central

    Salvador, Ângelo C.; Baptista, Inês; Barros, António S.; Gomes, Newton C. M.; Cunha, Ângela; Almeida, Adelaide; Rocha, Silvia M.

    2013-01-01

    A novel approach based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC×GC–ToFMS) was developed for the simultaneous screening of microbial and mite contamination level in cereals and coffee beans. The proposed approach emerges as a powerful tool for the rapid assessment of the microbial contamination level (ca. 70 min versus ca. 72 to 120 h for bacteria and fungi, respectively, using conventional plate counts), and mite contamination (ca. 70 min versus ca. 24 h). A full-factorial design was performed for optimization of the SPME experimental parameters. The methodology was applied to three types of rice (rough, brown, and white rice), oat, wheat, and green and roasted coffee beans. Simultaneously, microbiological analysis of the samples (total aerobic microorganisms, moulds, and yeasts) was performed by conventional plate counts. A set of 54 volatile markers was selected among all the compounds detected by GC×GC–ToFMS. Principal Component Analysis (PCA) was applied in order to establish a relationship between potential volatile markers and the level of microbial contamination. Methylbenzene, 3-octanone, 2-nonanone, 2-methyl-3-pentanol, 1-octen-3-ol, and 2-hexanone were associated to samples with higher microbial contamination level, especially in rough rice. Moreover, oat exhibited a high GC peak area of 2-hydroxy-6-methylbenzaldehyde, a sexual and alarm pheromone for adult mites, which in the other matrices appeared as a trace component. The number of mites detected in oat grains was correlated to the GC peak area of the pheromone. The HS-SPME/GC×GC–ToFMS methodology can be regarded as the basis for the development of a rapid and versatile method that can be applied in industry to the simultaneous assessment the level of microbiological contamination and for detection of mites in cereals grains and coffee beans. PMID:23613710

  4. Can volatile organic metabolites be used to simultaneously assess microbial and mite contamination level in cereal grains and coffee beans?

    PubMed

    Salvador, Angelo C; Baptista, Inês; Barros, António S; Gomes, Newton C M; Cunha, Angela; Almeida, Adelaide; Rocha, Silvia M

    2013-01-01

    A novel approach based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-ToFMS) was developed for the simultaneous screening of microbial and mite contamination level in cereals and coffee beans. The proposed approach emerges as a powerful tool for the rapid assessment of the microbial contamination level (ca. 70 min versus ca. 72 to 120 h for bacteria and fungi, respectively, using conventional plate counts), and mite contamination (ca. 70 min versus ca. 24 h). A full-factorial design was performed for optimization of the SPME experimental parameters. The methodology was applied to three types of rice (rough, brown, and white rice), oat, wheat, and green and roasted coffee beans. Simultaneously, microbiological analysis of the samples (total aerobic microorganisms, moulds, and yeasts) was performed by conventional plate counts. A set of 54 volatile markers was selected among all the compounds detected by GC×GC-ToFMS. Principal Component Analysis (PCA) was applied in order to establish a relationship between potential volatile markers and the level of microbial contamination. Methylbenzene, 3-octanone, 2-nonanone, 2-methyl-3-pentanol, 1-octen-3-ol, and 2-hexanone were associated to samples with higher microbial contamination level, especially in rough rice. Moreover, oat exhibited a high GC peak area of 2-hydroxy-6-methylbenzaldehyde, a sexual and alarm pheromone for adult mites, which in the other matrices appeared as a trace component. The number of mites detected in oat grains was correlated to the GC peak area of the pheromone. The HS-SPME/GC×GC-ToFMS methodology can be regarded as the basis for the development of a rapid and versatile method that can be applied in industry to the simultaneous assessment the level of microbiological contamination and for detection of mites in cereals grains and coffee beans. PMID:23613710

  5. [Investigation of nitrogen, phosphorus and microbial contamination in Laolongdong underground river system of Chongqing].

    PubMed

    Lan, Jia-Cheng; Yang, Ping-Heng; Ren, Kun; Chen, Xue-Bin; Xu, Xin; Hu, Ning

    2014-04-01

    With urbanization, groundwater in China has been widely polluted. Karst groundwater is important in southwest China, and would be difficult to recover once contaminated. NO3(-), PO4(3), NH4(+), total coliform, total E. coli and fecal coliform were chosen as indexes in the study of groundwater of Laolongdong Underground River System in Nanshan Mountain, Chongqing. After a few years of survey, the results showed that NO3(-), NH4(+) and PO4(3-) concentrations in the water were all above the nature value, especially NH4(+) and PO4(3-). The NO3(-) concentration of Guihuawan spring ranged from 19.78-68.55 mg x L(-1), in some months, above the recommended water quality guideline (50 mg x L(-1)) according to Standards for Drinking Water Quality set by World Health Organization. NH4(+) and PO4(3-) concentrations in Laolongdong underground river varied from 2.71-12.92 mg x L(-1) and 0.16-11.22 mg x L(-1). The NO3(-) concentration in Laolongdong underground river was lower than in karst spring; however, the concentrations of NH4(+) and PO4(3-) were higher than in the spring. It seemed that the NO3(-) concentration tended to decrease from 2008 to 2013 in the underground river caused by urbanization, reduction of farmland and reducing environment. However, waste water with a high PO4(3-) concentration led to an increasing trend in the PO4(3-) concentration in underground river. Microbial contamination was extremely serious, and even far exceeded class V of water quality standards of China. For example, the concentration of fecal coliform in the groundwater ranged from 3.4 x 10(4)-3.68 x 10(4) CFU x mL(-1). Because of the special hydrogeological structure, karst depressions, skylights and sinkholes can lead pollutants easily to the underground water. Agriculture activity, sewage from towns, enterprises and residential areas were the major sources of nitrogen, phosphorus and microbial contamination. PMID:24946579

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

    NASA Astrophysics Data System (ADS)

    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 to be controlled largely by Nitrospirae and the Miscellaneous Crenarchaeotal Group, suggesting a possible connection to nitrogen chemistry. From around 45 meters below seafloor (mbsf) to around 212 mbsf, the two groups have an inverse linear relationship (R2=0.96), and together account for 45×5% of the classified sequences.

  7. Measuring electric fields from surface contaminants with neutral atoms

    SciTech Connect

    Obrecht, J. M.; Wild, R. J.; Cornell, E. A. [JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440 (United States) and Department of Physics, University of Colorado, Boulder, Colorado 80309-0390 (United States)

    2007-06-15

    In this paper we demonstrate a technique of utilizing magnetically trapped neutral {sup 87}Rb atoms to measure the magnitude and direction of stray electric fields emanating from surface contaminants. We apply an alternating external electric field that adds to (or subtracts from) the stray field in such a way as to resonantly drive the trapped atoms into a mechanical dipole oscillation. The growth rate of the oscillation's amplitude provides information about the magnitude and sign of the stray field gradient. Using this measurement technique, we are able to reconstruct the vector electric field produced by surface contaminants. In addition, we can accurately measure the electric fields generated from adsorbed atoms purposely placed onto the surface and account for their systematic effects, which can plague a precision surface-force measurement. We show that baking the substrate can reduce the electric fields emanating from adsorbate and that the mechanism for reduction is likely surface diffusion, not desorption.

  8. Biocontainment of polychlorinated biphenyls (PCBs) on flat concrete surfaces by microbial carbonate precipitation.

    PubMed

    Okwadha, George D O; Li, Jin

    2011-10-01

    In this study, a biosealant obtained from microbial carbonate precipitation (MCP) was evaluated as an alternative to an epoxy-coating system. A bacterium Sporosarcina pasteurii strain ATCC 11859, which metabolizes urea and precipitates calcite in a calcium-rich environment, was used in this study to generate the biosealant on a PCB-contaminated concrete surface. Concrete cylinders measuring 3 in (76.2 mm) by 6 in (152.4 mm) were made in accordance with ASTM C33 and C192 and used for this purpose. The PCB, urea, Ca(2+), and bacterial cell concentrations were set at 10 ppm, 666 mM, 250 mM, and about 2.1 × 10(8) cells mL(-1), respectively. The results indicate that the biosealed surfaces reduced water permeability by 1-5 orders of magnitude, and had a high resistance to carbonation. Since the MCP biosealant is thermally stable under temperatures of up to 840 °C, the high temperatures that normally exist in the surrounding equipment, which may contain PCB-based fluids, have no effect on the biosealed surfaces. Consequently, there is greater potential to obtain a stronger, coherent, and durable surface by MCP. No measurable amount of PCBs was detected in the permeating water, indicating that the leaching water, if any, will have a minimum impact on the surrounding environment. PMID:21696884

  9. Microbial Diversity and Bioremediation of aHydrocarbon-Contaminated Aquifer (Vega Baja, Puerto Rico)

    SciTech Connect

    Rodriguez-Martinez, E.M.; Perez, Ernie X.; Schadt, ChristopherW.; Zhou, Jizhong; Massol-Deya, Arturo A.

    2006-09-30

    Hydrocarbon contamination of groundwater resources hasbecome a major environmental and human health concern in many parts ofthe world. Our objectives were to employ both culture andculture-independent techniques to characterize the dynamics of microbialcommunity structure within a fluidized bed reactor used to bioremediate adiesel-contaminated groundwater in a tropical environment. Under normaloperating conditions, 97 to 99 percent of total hydrocarbons were removedwith only 14 min hydraulic retention time. Over 25 different cultureswere isolated from the treatment unit (96 percent which utilized dieselconstituents as sole carbon source). Approximately 20 percent of theisolates were also capable of complete denitrification to nitrogen gas.Sequence analysis of 16S rDNA demonstrated ample diversity with mostbelonging to the infinity, beta and gamma subdivision of theProteobacteria, Bacilli, and Actinobacteria groups. Moreover, the geneticconstitution of the microbial community was examined at multiple timepoints with a Functional Gene Array (FGA) containing over 12,000 probesfor genes involved in organic degradation and major biogeochemicalcycles. Total community DNA was extracted and amplified using anisothermal phi29 polymerase-based technique, labeled with Cy5 dye, andhybridized to the arrays in 50 percent formimide overnight at 50 degreesC. Cluster analysis revealed comparable profiles over the course oftreatment suggesting the early selection of a very stable microbialcommunity. A total of 270 genes for organic contaminant degradation(including naphthalene, toluene [aerobic and anaerobic], octane,biphenyl, pyrene, xylene, phenanthrene, and benzene); and 333 genesinvolved in metabolic activities (nitrite and nitrous oxide reductases[nirS, nirK, and nosZ], dissimilatory sulfite reductases [dsrAB],potential metal reducing C-type cytochromes, and methane monooxygenase[pmoA]) were repeatedly detected. Genes for degradation of MTBE,nitroaromatics and chlorinated compounds werealso present, indicating abroad catabolic potential of the treatment unit. FGA's demonstrated theearly establishment of a diverse community with concurrent aerobic andanaerobic processes contributing to the bioremediationprocess.

  10. Explosive Contamination from Substrate Surfaces: Differences and Similarities in Contamination Techniques using RDX and C-4

    SciTech Connect

    C.J. Miller; T.S. Yoder

    2010-06-01

    The amount of time that an explosive is present on the surface of a material is dependent upon the original amount of explosive on the surface, temperature, humidity, rain, etc. This laboratory study focused on looking at similarities and differences in three different surface contamination techniques that are used when performance testing explosive trace detection equipment in an attempt to determine how effective the techniques are at replicating actual field samples. The three techniques used were dry transfer deposition of solutions using the Transportation Security Laboratory (TSL) patented dry transfer techniques (US patent 6470730), direct deposition of explosive standards, and fingerprinting of actual explosives. Explosives were deposited on the surface of one of five substrates using one of the three different deposition techniques. The process was repeated for each surface type using each contamination technique. The surface types used were: 50% cotton/50% polyester as found in T-shirts, 100% cotton with a smooth surface such as that found in a cotton dress shirt, 100% cotton on a rough surface such as that found on canvas or denim, suede leather such as might be found on jackets, purses, or shoes, and metal obtained from a car hood at a junk yard. The samples were not pre-cleaned prior to testing and contained sizing agents, and in the case of the metal, oil and dirt. The substrates were photographed using a Zeiss Discover V12 stereoscope with Axiocam ICc1 3 megapixel digital camera to determine the difference in the crystalline structure and surface contamination in an attempt to determine differences and similarities associated with current contamination techniques.

  11. Use of Spatial Sampling and Microbial Source-Tracking Tools for Understanding Fecal Contamination at Two Lake Erie Beaches

    USGS Publications Warehouse

    Francy, Donna S.; Bertke, Erin E.; Finnegan, Dennis P.; Kephart, Christopher M.; Sheets, Rodney A.; Rhoades, John; Stumpe, Lester

    2006-01-01

    Source-tracking tools were used to identify potential sources of fecal contamination at two Lake Erie bathing beaches: an urban beach (Edgewater in Cleveland, Ohio) and a beach in a small city (Lakeshore in Ashtabula, Ohio). These tools included identifying spatial patterns of Escherichia coli (E. coli) concentrations in each area, determining weather patterns that caused elevated E. coli, and applying microbial source tracking (MST) techniques to specific sites. Three MST methods were used during this study: multiple antibiotic resistance (MAR) indexing of E. coli isolates and the presence of human-specific genetic markers within two types of bacteria, the genus Bacteroides and the species Enterococcus faecium. At Edgewater, sampling for E. coli was done during 2003-05 at bathing-area sites, at nearshore lake sites, and in shallow ground water in foreshore and backshore areas. Spatial sampling at nearshore lake sites showed that fecal contamination was most likely of local origin; E. coli concentrations near the mouths of rivers and outfalls remote to the beach were elevated (greater than 235 colony-forming units per 100 milliliters (CFU/100 mL)) but decreased along transport pathways to the beach. In addition, E. coli concentrations were generally highest in bathing-area samples collected at 1- and 2-foot water depths, midrange at 3-foot depths, and lowest in nearshore lake samples typically collected 150 feet from the shoreline. Elevated E. coli concentrations at bathing-area sites were generally associated with increased wave heights and rainfall, but not always. E. coli concentrations were often elevated in shallow ground-water samples, especially in samples collected less than 10 feet from the edge of water (near foreshore area). The interaction of shallow ground water and waves may be a mechanism of E. coli storage and accumulation in foreshore sands. Infiltration of bird feces through sand with surface water from rainfall and high waves may be concentrating E. coli in shallow ground water in foreshore and backshore sands. At Lakeshore, sampling for E. coli was done at bathing-area, nearshore lake, and parking-lot sites during 2004-05. Low concentrations of E. coli at nearshore lake sites furthest from the shoreline indicated that fecal contamination was most likely of local origin. High concentrations of E. coli in water and bed sediments at several nearshore lake sites showed that contamination was emanating from several points along the shoreline during wet and dry weather, including the boat ramp, an area near the pond drainage, and parking-lot sediments. Physical evidence confirmed that runoff from the parking lot leads to degradation of water quality at the beach. MST samples were collected to help interpret spatial findings and determine whether sources of fecal contamination were from wastewater or bird feces and if a human-specific marker was present. MAR indices were useful in distinguishing between bird feces and wastewater sources because they were about 10 times higher in the latter. The results from MAR indices agreed with results from the two human-specific markers in some but not all of the samples tested. Bacteroides and enterococci human-specific markers were found on one day at Edgewater and two days at Lakeshore. On three days at Edgewater and two days at Lakeshore, the MAR index indicated a mixed source, but neither marker was found in bathing-water samples; this may be because bacterial indicator concentrations were too low to detect a marker. Multiple tools are needed to help identify sources of fecal contamination at coastal beaches. Spatial sampling identified patterns in E. coli concentrations and yielded information on the physical pathways of contamination. MST methods provided information on whether the source was likely of human or nonhuman origin only; however, MST did not provide information on the pathways of contamination.

  12. Microbial Contamination on Used Surgical Masks among Hospital Personnel and Microbial Air Quality in their Working Wards: A Hospital in Bangkok

    PubMed Central

    Luksamijarulkul, Pipat; Aiempradit, Natkitta; Vatanasomboon, Pisit

    2014-01-01

    Objective To assess the relationship of bacterial and fungal contamination on used surgical masks worn by the hospital personnel and microbial air quality in their working wards. Methods This is a cross-sectional study of 230 used surgical masks collected from 214 hospital personnel, and 215 indoor air samples collected from their working wards to culture for bacterial and fungal counts. This study was carried out at the hospital in Bangkok. Group or genus of isolated bacteria and fungi were preliminarily identified by Gram’s stain and lacto-phenol cotton blue. Data were analyzed using paired t-test and Pearson’s correlation coefficient at the significant level of p<0.050. Results Means and standard deviation of bacterial and fungal contamination on inside area of the used masks were 47 ± 56 and 15 ± 9 cfu/ml/piece, and on outside area were 166 ± 199 and 34 ± 18 cfu/ml/piece, respectively, p<0.001. The bacterial and fungal contamination on used masks from hospital personnel working in the male and female medical wards and out-patient department, as well as the bacterial and fungal counts of the indoor air sample collected from the same area were relatively higher than the other wards. The predominant isolated bacteria and fungi contaminated on inside and outside areas of the used masks and air samples were similar (Staphylococcus spp. and Aspergillus spp.; respectively). For its relationship, results found that bacterial and fungal counts in air samples showed significantly positive correlation with the bacterial contamination load on outside area of the used masks, r=0.16, p=0.018 and r=0.21, p=0.003, respectively. Conclusion High bacterial contamination on outside area of the used masks was demonstrated, and it showed a significant correlation with microbial air quality of working wards. PMID:25337311

  13. Characterization of Archaeal Community in Contaminated and Uncontaminated Surface Stream Sediments

    SciTech Connect

    Porat, Iris [ORNL; Vishnivetskaya, Tatiana A [ORNL; Mosher, Jennifer J [ORNL; Brandt, Craig C [ORNL; Yang, Zamin [ORNL; Brooks, Scott C [ORNL; Liang, Liyuan [ORNL; Drake, Meghan M [ORNL; Podar, Mircea [ORNL; Brown, Steven D [ORNL; Palumbo, Anthony Vito [ORNL

    2010-01-01

    Abstract Archaeal communities from mercury and uranium-contaminated freshwater stream sediments were characterized and compared to archaeal communities present in an uncontaminated stream located in the vicinity of Oak Ridge, TN, USA. The distribution of the Archaea was determined by pyrosequencing analysis of the V4 region of 16S rRNA amplified from 12 streambed surface sediments. Crenarchaeota comprised 76% of the 1,670 archaeal sequences and the remaining 24% were from Euryarchaeota. Phylogenetic analysis further classified the Crenarchaeota as a Freshwater Group, Miscellaneous Crenarchaeota group, Group I3, Rice Cluster VI and IV, Marine Group I and Marine Benthic Group B; and the Euryarchaeota into Methanomicrobiales, Methanosarcinales, Methanobacteriales, Rice Cluster III, Marine Benthic Group D, Deep Sea Hydrothermal Vent Euryarchaeota 1 and Eury 5. All groups were previously described. Both hydrogen- and acetate-dependent methanogens were found in all samples. Most of the groups (with 60% of the sequences) described in this study were not similar to any cultivated isolates, making it difficult to discern their function in the freshwater microbial community. A significant decrease in the number of sequences, as well as in the diversity of archaeal communities was found in the contaminated sites. The Marine Group I, including the ammonia oxidizer Nitrosopumilus maritimus, was the dominant group in both mercury and uranium/nitrate-contaminated sites. The uranium-contaminated site also contained a high concentration of nitrate, thus Marine Group I may play a role in nitrogen cycle.

  14. Microbial community gene expression in ocean surface waters

    PubMed Central

    Frias-Lopez, Jorge; Shi, Yanmei; Tyson, Gene W.; Coleman, Maureen L.; Schuster, Stephan C.; Chisholm, Sallie W.; DeLong, Edward F.

    2008-01-01

    Metagenomics is expanding our knowledge of the gene content, functional significance, and genetic variability in natural microbial communities. Still, there exists limited information concerning the regulation and dynamics of genes in the environment. We report here global analysis of expressed genes in a naturally occurring microbial community. We first adapted RNA amplification technologies to produce large amounts of cDNA from small quantities of total microbial community RNA. The fidelity of the RNA amplification procedure was validated with Prochlorococcus cultures and then applied to a microbial assemblage collected in the oligotrophic Pacific Ocean. Microbial community cDNAs were analyzed by pyrosequencing and compared with microbial community genomic DNA sequences determined from the same sample. Pyrosequencing-based estimates of microbial community gene expression compared favorably to independent assessments of individual gene expression using quantitative PCR. Genes associated with key metabolic pathways in open ocean microbial species—including genes involved in photosynthesis, carbon fixation, and nitrogen acquisition—and a number of genes encoding hypothetical proteins were highly represented in the cDNA pool. Genes present in the variable regions of Prochlorococcus genomes were among the most highly expressed, suggesting these encode proteins central to cellular processes in specific genotypes. Although many transcripts detected were highly similar to genes previously detected in ocean metagenomic surveys, a significant fraction (?50%) were unique. Thus, microbial community transcriptomic analyses revealed not only indigenous gene- and taxon-specific expression patterns but also gene categories undetected in previous DNA-based metagenomic surveys. PMID:18316740

  15. Molecular-Scale Characterization of Natural Organic Matter From A Uranium Contaminated Aquifer and its Utilization by Native Microbial Communities

    NASA Astrophysics Data System (ADS)

    Mouser, P. J.; Wilkins, M. J.; Williams, K. H.; Smith, D. F.; Paša-Toli?, L.

    2011-12-01

    The availability and form of natural organic matter (NOM) strongly influences rates of microbial metabolism and associated redox processes in subsurface environments. This is an important consideration in metal-contaminated aquifers, such as the DOE's Rifle Integrated Field Research Challenge (IFRC) site, where naturally occurring suboxic conditions in groundwater may play an important function in controlling uranium mobility, and therefore the long-term stewardship of the site. Currently, the biophysiochemical processes surrounding the nature of the aquifer and its role in controlling the fate and transport of uranium are poorly understood. Using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) with electrospray ionization (ESI), we characterized dissolved organic matter (DOM) chemistry for three surface and groundwater sources at Rifle and assessed microbial utilization in batch incubation experiments. FT-ICR-MS uniquely offers ultrahigh mass measurement accuracy and resolving power for polar organics, in addition to enabling elemental composition assignments of these compounds. Samples were collected from the Colorado River, a shallow groundwater aquifer adjacent to the river, and a spring/seep discharge point upgradient from the aquifer. DOM was concentrated and purified from each source and analyzed using FT-ICR-MS with ESI. We identified between 6,000 and 7,000 formulae at each location, with the river sample having the smallest and the spring sample having the largest number of identified peaks. The groundwater and spring samples contained DOM with a large percentage of formulae containing nitrogen and sulfur species, while the river sample was dominated by carbon, hydrogen, and oxygen species. Less than 38% of the formulae were shared between any two samples, indicating a significant level of uniqueness across the samples. Unsaturated hydrocarbons, cellulose, and lipids were rapidly utilized by indigenous bacteria during a 24-day incubation period, and presumably transformed to more recalcitrant lignins and protein-type molecules. These findings indicate that FT-ICR-MS with ESI is an effective method for characterizing molecular-scale differences in DOM from complex environments. We also provide preliminary evidence that certain DOM fractions are more efficiently utilized by indigenous microbial communities and likely play an important role in controlling reducing conditions in heterogeneous subsurface environments.

  16. Screening Surface Contamination with BetaCage

    SciTech Connect

    Schnee, R. W.; Grant, D. R.; Poinar, K. [Department of Physics, Case Western Reserve University, Cleveland, OH 44106 (United States); Ahmed, Z.; Golwala, S. R. [Department of Physics, California Institute of Technology, Pasadena, CA 91125 (United States)

    2007-03-28

    Existing screening facilities are insufficiently sensitive to meet the needs of rare-event experiments for low-energy electron emitters and alpha-decaying isotopes. To provide such screening, the BetaCage will be a low-background, atmospheric-pressure neon drift chamber with unprecedented sensitivity to emitters of low-energy electrons and alpha particles. Minimization of the detector mass and use of radiopure materials reduce background events. The chamber design accepts nearly all alphas and low-energy electrons from the sample surface while allowing excellent rejection of residual backgrounds. A non-radiopure prototype is under construction to test the design. The BetaCage will provide new infrastructure for rare-event science as well as for a wider community that uses radioactive screening for areas including archaeology, biology, climatology, environmental science, geology, planetary science, and integrated-circuit quality control.

  17. Composition suitable for decontaminating a porous surface contaminated with cesium

    DOEpatents

    Kaminski, Michael D.; Finck, Martha R.; Mertz, Carol J.

    2010-06-15

    A method of decontaminating porous surfaces contaminated with water soluble radionuclides by contacting the contaminated porous surfaces with an ionic solution capable of solubilizing radionuclides present in the porous surfaces followed by contacting the solubilized radionuclides with a gel containing a radionuclide chelator to bind the radionuclides to the gel, and physically removing the gel from the porous surfaces. A dry mix is also disclosed of a cross-linked ionic polymer salt, a linear ionic polymer salt, a radionuclide chelator, and a gel formation controller present in the range of from 0% to about 40% by weight of the dry mix, wherein the ionic polymer salts are granular and the non cross-linked ionic polymer salt is present as a minor constituent.

  18. Surface contamination on silver and its effects on cohesion in silver-silver solid state bonding

    Microsoft Academic Search

    D. T. Larson; J. R. Roper

    1984-01-01

    Investigations concerning the effect of atmospheric surface contaminants on the cohesion of silver in the solid state bonding of metals were conducted. Surface contaminants found by Auger electron spectroscopy were chlorine, sulfur, oxygen, and carbon, with the major contaminant being carbon. Examination of the diffusion behavior of the surface contaminants at elevated temperatures showed that oxygen and carbon were stable

  19. A Limited Microbial Consortium Is Responsible for Extended Bioreduction of Uranium in a Contaminated Aquifer ?†

    PubMed Central

    Gihring, Thomas M.; Zhang, Gengxin; Brandt, Craig C.; Brooks, Scott C.; Campbell, James H.; Carroll, Susan; Criddle, Craig S.; Green, Stefan J.; Jardine, Phil; Kostka, Joel E.; Lowe, Kenneth; Mehlhorn, Tonia L.; Overholt, Will; Watson, David B.; Yang, Zamin; Wu, Wei-Min; Schadt, Christopher W.

    2011-01-01

    Subsurface amendments of slow-release substrates (e.g., emulsified vegetable oil [EVO]) are thought to be a pragmatic alternative to using short-lived, labile substrates for sustained uranium bioimmobilization within contaminated groundwater systems. Spatial and temporal dynamics of subsurface microbial communities during EVO amendment are unknown and likely differ significantly from those of populations stimulated by soluble substrates, such as ethanol and acetate. In this study, a one-time EVO injection resulted in decreased groundwater U concentrations that remained below initial levels for approximately 4 months. Pyrosequencing and quantitative PCR of 16S rRNA from monitoring well samples revealed a rapid decline in groundwater bacterial community richness and diversity after EVO injection, concurrent with increased 16S rRNA copy levels, indicating the selection of a narrow group of taxa rather than a broad community stimulation. Members of the Firmicutes family Veillonellaceae dominated after injection and most likely catalyzed the initial oil decomposition. Sulfate-reducing bacteria from the genus Desulforegula, known for long-chain fatty acid oxidation to acetate, also dominated after EVO amendment. Acetate and H2 production during EVO degradation appeared to stimulate NO3?, Fe(III), U(VI), and SO42? reduction by members of the Comamonadaceae, Geobacteriaceae, and Desulfobacterales. Methanogenic archaea flourished late to comprise over 25% of the total microbial community. Bacterial diversity rebounded after 9 months, although community compositions remained distinct from the preamendment conditions. These results demonstrated that a one-time EVO amendment served as an effective electron donor source for in situ U(VI) bioreduction and that subsurface EVO degradation and metal reduction were likely mediated by successive identifiable guilds of organisms. PMID:21764967

  20. Environmental influences on the partitioning and diffusion of hydrophobic organic contaminants in microbial biofilms.

    PubMed

    Wicke, Daniel; Böckelmann, Uta; Reemtsma, Thorsten

    2008-03-15

    A biofilm reactor was used to investigate kinetic and thermodynamic aspects of the sorption of polycyclic aromatic hydrocarbons (PAH) as model compounds for hydrophobic organic contaminants (HOC) to intact microbial biofilms. Effective diffusion coefficients are in the range of 10(-10) cm2 x s(-1) resulting in equilibration times of more than 3 days for a biofilm of 100 microm thickness. Diffusion in the biofilm was strongly temperature-dependent and increased by a factor of 3 (phenanthrene) to 6 (fluoranthene, pyrene) between 5 and 35 degrees C. Drying and rewetting of the biofilm as well as the inclusion of Ca2+ ions and of humic acids all strengthened the biofilm rigidity and slowed down the diffusion of PAH. The later two factors also influenced the thermodynamics of the process as they supported the partitioning of PAH into the biofilm. Humic acid inclusion from solution into the biofilm illustrates that a microbial biofilm can act as a primer allowing for the buildup of a particulate organic phase from dissolved organic matter. PAH metabolites (3-hydroxy-phenanthrene and 1-hydroxy-2-naphthoic acid) showed lower partition coefficients as compared to their parent compounds and 3-hydroxy-phenanthrene also showed a higher diffusion constant, indicating that these transformation products would be easily released into the water phase upon formation during PAH biodegradation in a biofilm. These results allow the quantification of the influence of environmental conditions on a biofilm's function as a sink or as a diffusion barrier for PAH from aqueous solution, and they indicate the importance of kinetic aspects of this partitioning process. PMID:18409626

  1. Method for in-situ cleaning of carbon contaminated surfaces

    DOEpatents

    Klebanoff, Leonard E.; Grunow, Philip; Graham Jr., Samuel

    2006-12-12

    Activated gaseous species generated adjacent a carbon contaminated surface affords in-situ cleaning. A device for removing carbon contamination from a surface of the substrate includes (a) a housing defining a vacuum chamber in which the substrate is located; (b) a source of gaseous species; and (c) a source of electrons that are emitted to activate the gaseous species into activated gaseous species. The source of electrons preferably includes (i) a filament made of a material that generates thermionic electron emissions; (ii) a source of energy that is connected to the filament; and (iii) an electrode to which the emitted electrons are attracted. The device is particularly suited for photolithography systems with optic surfaces, e.g., mirrors, that are otherwise inaccessible unless the system is dismantled. A method of removing carbon contaminants from a substrate surface that is housed within a vacuum chamber is also disclosed. The method employs activated gaseous species that react with the carbon contaminants to form carbon containing gaseous byproducts.

  2. An Exercise in Evaluating the Contamination Potential of Surface Impoundments.

    ERIC Educational Resources Information Center

    Tinker, John R., Jr.

    1982-01-01

    Outlines a laboratory procedure which enables students to evaluate the contamination potential of surface impoundments and apply basic principles of hydrogeology to the land disposal of waste material. Includes a list of materials needed and directions for the instructor. (Author/DC)

  3. RESUSPENSION OF PLUTONIUM FROM CONTAMINATED LAND SURFACES: METEOROLOGICAL FACTORS

    EPA Science Inventory

    A literature review is presented in a discussion of the relevance of meteorological factors on the resuspension of plutonium from contaminated land surfaces. The physical processes of resuspension based on soil erosion work are described. Some of the models developed to simulate ...

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  5. Microbial Surfaces and their Effects on Carbonate Mineralization

    NASA Astrophysics Data System (ADS)

    Cappuccio, J. A.; Pillar, V. D.; Lui, G. V.; Ajo-Franklin, C.

    2011-12-01

    Geologic carbon dioxide sequestration, the underground storage of carbon dioxide (CO2), will be an essential component of climate change mitigation. Carbonate minerals are a promising form of stable CO2 storage, but their geologic formation is slow. Many microbes can increase the rate of carbonate mineral formation; however the mechanisms of such mineralization are largely unknown. Hypothesized mechanisms include metabolic processes that alter pH and supersaturation, as well as cell surface properties that induce mineral nucleation. This work systematically investigates these mechanisms by allowing calcium carbonate (CaCO3) to form in the presence or absence of microbes with various surfaces features included Escherichia coli, Synechocystis sp. PCC 6803, Caulobacter vibrioides, and Lysinibacilllus sphaericus. Surprisingly, formation of stable crystalline CaCO3 was accelerated by the presence of all microbes relative to abiotic solutions. This rate acceleration also occurred for metabolically inactive bacteria, indicating that metabolic activity was not the operating mechanism. Rather, since the CaCO3 crystals increased in number as the cell density increased, these results indicate that many bacterial species accelerate the nucleation of CaCO3 crystals. To understand the role of specific biomolecules on nucleation, we used genetic mutants with altered lipopolysaccharides (LPS) and crystalline surface layer proteins (S-layers). Bacterial surface charge and cation binding was assessed using zeta potential measurements and correlated to the bacterial surface chemistry and biomineralization experiments with varying Ca2+ concentrations. From these results, we postulate that the S-layer surfaces can selectively attract Ca2+ ions, serving as nucleation sites for CaCO3, thereby accelerating crystal formation. These observations provide substantive evidence for a non-specific nucleation mechanism, and stress the importance of microbes, even dead ones, on the rate of formation of carbonate minerals. This work also indicates that additional microbial engineering specifically targeted to S-layer proteins could optimize these interactions and be used to implement the sequestration of CO2 as stable mineral carbonates on an accelerated timescale.

  6. Effect of organic contamination upon microbial distributions and heterotrophic uptake in a cape cod, mass., aquifer

    USGS Publications Warehouse

    Harvey, R.W.; Smith, R.L.; George, L.

    1984-01-01

    Bacterial abundance, distribution, and heterotrophic uptake in a freshwater aquifer contaminated by treated sewage were determined from analyses of groundwater and sediment-core samples. The number of free-living (unattached) bacteria in contaminated groundwater declined steadily with increasing distance from the source of sewage infiltration, from 1.94 ?? (?? 0.20) x 106 ml-1 at 0.21 km to 0.25 (?? 0.02) x 106 ml-1 at 0.97 km. Bacterial abundance in groundwater sampled at 0.31 km correlated strongly with specific conductance and increased sharply from 4.0 (?? 0.3) x 104 ml-1 at a depth of 6 m to 1.58 (?? 0.12) x 106 ml-1 at 14 m, then declined at 20 and 31 m to 1.29 (?? 0.12) x 106 and 0.96 (?? 0.12) x 106 ml-1, respectively. A majority of the bacteria in contaminated and uncontaminated zones of the aquifer were bound to the surfaces of particulates, <60 ??m in diameter. The glucose uptake rate, assayed at in situ and 5 ??M concentrations, declined steadily in contaminated groundwater sampled along a transect. A preparative wet-sieving technique for use in processing core samples for bacterial enumeration is described and evaluated.

  7. Stable isotope fractionation related to microbial nitrogen turnover in constructed wetlands treating contaminated groundwater

    NASA Astrophysics Data System (ADS)

    Voloshchenko, O.; Knoeller, K.

    2013-12-01

    To improve the efficiency of ground- and wastewater treatment in constructed wetlands (CWs), better understanding of the occurring processes is necessary. This research explores N-isotope fractionations associated with the removal of ammonium from contaminated groundwater in pilot-scale CWs downstream of the chemical industrial area Leuna, Germany. The groundwater at the site is contaminated mainly by organic (BTEX, MTBE) and inorganic compounds (ammonium). We assume that the anaerobic ammonium oxidation (ANAMMOX) plays an important role in nitrogen removal in these CWs. However, to date, interactions between processes of aerobic and anaerobic ammonium oxidation in CWs still have not been well explored. Especially, the importance of the ANAMMOX process for the nitrogen removal is generally accepted, but its role in CWs is quite unknown. For this aim, three CWs were chosen: planted horizontal subsurface flow (HSSF); unplanted HSSF, and floating plant root mat (FPRM). Water samples were taken at the inflow and outflow as well as from the pore space at different distances (1, 2.5 and 4 m) from the inlet and at different depths (20, 30 and 40 cm in the HSSF-CWs, 30 cm in the FPRM). Samples were collected in a time interval of 1 to 6 weeks during 1 year with the exception of the winter season. Physicochemical parameters, nitrogen isotope signatures of ammonium, as well as nitrogen and oxygen isotope signatures of nitrate were analysed. Within the CWs, spatial concentration gradients of the nitrogen species (ammonium and nitrate) are observed. N-isotope variations of ammonium and nitrate are interpreted according to the prevailing processes of the N-transformations. Based on isotope mass-balance approach microbial processes such as nitrification, denitrification, and ANAMMOX are quantified. DNA from biofilms at roots and gravel was extracted using FastDNA Spin Kit For Soil (MP Biomedicals). PCR, quantitative PCR, cloning, and sequencing were applied with the purpose of getting information about the abundance and the community of key players of the N-cycle. Pyrosequencing and specific FISH probes in connection with confocal laser scanning microscopy will give information about structure and spatial distribution of the microbial nitrogen transforming community.

  8. X-ray fluorescence surface contaminant analyzer: A feasibility study

    NASA Technical Reports Server (NTRS)

    Eldridge, Hudson B.

    1988-01-01

    The bonding of liner material to the inner metal surfaces of solid rocket booster cases is adversely affected by minute amounts of impurities on the metal surface. Suitable non-destructive methods currently used for detecting these surface contaminants do not provide the means of identifying their elemental composition. The feasibility of using isotopic source excited energy dispersive X-ray fluorescence as a possible technique for elemental analysis of such contaminants is investigated. A survey is made of the elemental compositions of both D-6ac steel, a common construction material for the booster cases, and Conoco HD-2 grease, a common surface contamination. Source and detector choices that maximize signal to noise ratio in a Recessed Source Geometry are made. A Monte Carlo simulation is then made of the optimized device incorporating the latest available X-ray constants at the energy of the chosen source to determine the device's response to a D-6ac steel surface contained with Conoco HD-2 grease.

  9. Surface Sampling Methods for Bacillus anthracis Spore Contamination

    PubMed Central

    Hein, Misty J.; Taylor, Lauralynn; Curwin, Brian D.; Kinnes, Gregory M.; Seitz, Teresa A.; Popovic, Tanja; Holmes, Harvey T.; Kellum, Molly E.; McAllister, Sigrid K.; Whaley, David N.; Tupin, Edward A.; Walker, Timothy; Freed, Jennifer A.; Small, Dorothy S.; Klusaritz, Brian; Bridges, John H.

    2002-01-01

    During an investigation conducted December 17–20, 2001, we collected environmental samples from a U.S. postal facility in Washington, D.C., known to be extensively contaminated with Bacillus anthracis spores. Because methods for collecting and analyzing B. anthracis spores have not yet been validated, our objective was to compare the relative effectiveness of sampling methods used for collecting spores from contaminated surfaces. Comparison of wipe, wet and dry swab, and HEPA vacuum sock samples on nonporous surfaces indicated good agreement between results with HEPA vacuum and wipe samples. However, results from HEPA vacuum sock and wipe samples agreed poorly with the swab samples. Dry swabs failed to detect spores >75% of the time they were detected by wipe and HEPA vacuum samples. Wipe samples collected after HEPA vacuum samples and HEPA vacuum samples after wipe samples indicated that neither method completely removed spores from the sampled surfaces. PMID:12396930

  10. Surface-contamination-related thermal instability in GaAs

    NASA Astrophysics Data System (ADS)

    Wang, Faa-Ching; Rau, Mann-Fu; Liao, De-Dui; Carter, Ronald

    1990-08-01

    The instability of the electrical properties of semi-insulating GaAs materials has been investigated. The presence of chemical contaminants on the surface of the finished wafers is responsible. Simulated thermal conversion using intentional carbon-ion implantation indicates larger concentrations for the possible contaminants on the surface than that in the bulk. The contribution to instability due to preferential gettering of imperfections from bulk by the implant and annealing process was eliminated using intentional Ar-ion implantation. For the samples which exhibited a change in electrical conduction type, a linear relationship between the thickness of the type-converted surface layer and the square root of heat treatment time was observed. It is proposed that the causes for the instability are governed by conventional diffusion mechanisms with multiple electrically active species involved. A positive correlation was also observed between thermally induced electrical instability in ion-implanted material and a reduction in activation, peak carrier density, and Hall mobility.

  11. Apparatus for in situ cleaning of carbon contaminated surfaces

    DOEpatents

    Klebanoff, Leonard E.; Grunow, Philip; Graham Jr., Samuel

    2004-08-10

    Activated gaseous species generated adjacent a carbon contaminated surface affords in-situ cleaning. A device for removing carbon contamination from a surface of the substrate includes (a) a housing defining a vacuum chamber in which the substrate is located; (b) a source of gaseous species; and (c) a source of electrons that are emitted to activate the gaseous species into activated gaseous species. The source of electrons preferably includes (i) a filament made of a material that generates thermionic electron emissions; (ii) a source of energy that is connected to the filament; and (iii) an electrode to which the emitted electrons are attracted. The device is particularly suited for photolithography systems with optic surfaces, e.g., mirrors, that are otherwise inaccessible unless the system is dismantled.

  12. IDENTIFYING THE SIGNATURE OF THE NATURAL ATTENUATION IN THE MICROBIAL ECOLOGY OF HYDROCARBON CONTAMINATED GROUNDWATER USING MOLECULAR METHODS AND &LDQUO;BUG TRAPS&RDQUO;

    EPA Science Inventory

    These related projects have combined biological molecular methods and a novel passive sampling system (bio-trap) to produce a technology that will allow the active component of any contaminated groundwater microbial community to be investigated. Conventional sampling methods c...

  13. On-Line Detection of Microbial Contaminations in Animal Cell Reactor Cultures Using an Electronic Nose Device

    Microsoft Academic Search

    Karl Kreij; Carl-Fredrik Mandenius; João J. Clemente; António Eduardo Cunha; Sandra M. S. Monteiro; Manuel J. T. Carrondo; Friedemann Hesse; Maria Milagros Bassani de los Molinas; Roland Wagner; Otto-Wilhelm Merten; Cécile Gény-Fiamma; Wolfgang Leger; Herbert Wiesinger-Mayr; Dethard Müller; Hermann Katinger; Per Mårtensson; Thomas Bachinger; Jan Mitrovics

    2005-01-01

    An electronic nose (EN) device was used to detect microbial and viral contaminations in a variety of animal cell culture systems.\\u000a The emission of volatile components from the cultures accumulated in the bioreactor headspace, was sampled and subsequently\\u000a analysed by the EN device. The EN, which was equipped with an array of 17 chemical gas sensors of varying selectivity towards

  14. Horizontal arrangement of anodes of microbial fuel cells enhances remediation of petroleum hydrocarbon-contaminated soil.

    PubMed

    Zhang, Yueyong; Wang, Xin; Li, Xiaojing; Cheng, Lijuan; Wan, Lili; Zhou, Qixing

    2015-02-01

    With the aim of in situ bioremediation of soil contaminated by hydrocarbons, anodes arranged with two different ways (horizontal or vertical) were compared in microbial fuel cells (MFCs). Charge outputs as high as 833 and 762C were achieved in reactors with anodes horizontally arranged (HA) and vertically arranged (VA). Up to 12.5 % of the total petroleum hydrocarbon (TPH) was removed in HA after 135 days, which was 50.6 % higher than that in VA (8.3 %) and 95.3 % higher than that in the disconnected control (6.4 %). Hydrocarbon fingerprint analysis showed that the degradation rates of both alkanes and polycyclic aromatic hydrocarbons (PAHs) in HA were higher than those in VA. Lower mass transport resistance in the HA than that of the VA seems to result in more power and more TPH degradation. Soil pH was increased from 8.26 to 9.12 in HA and from 8.26 to 8.64 in VA, whereas the conductivity was decreased from 1.99 to 1.54 mS/cm in HA and from 1.99 to 1.46 mS/cm in VA accompanied with the removal of TPH. Considering both enhanced biodegradation of hydrocarbon and generation of charge in HA, the MFC with anodes horizontally arranged is a promising configuration for future applications. PMID:25189807

  15. Anaerobic microbial dechlorination: an approach to on-site treatment of toxaphene-contaminated soil

    SciTech Connect

    Mirsatari, S.G.; McChesney, M.M.; Craigmill, A.C.; Winterlin, W.L.; Seiber, J.N.

    1987-12-01

    Enhanced microbial degradation of toxaphene by natural microorganisms occurred in soil and sediment amended with organic matter kept under anaerobic (flooded) conditions. Laboratory experiments yielded a dissipation half-life of approximately 3 and 1 week for soil and sediment, respectively, containing 10 ppm of technical toxaphene and a 1% alfalfa meal amendment. Dissipation was accompanied by an increase in early eluting gas chromatographic peaks and a decrease in later eluting peaks, indicating that dechlorination had occurred. Enhanced anaerobic dissipation also took place in soil containing 500 ppm of toxaphene, although at a lesser rate than at 10 ppm, and when cotton gin waste was used as amendment in place of alfalfa meal. Sediment in a toxaphene-contaminated pesticide waste disposal ditch was amended with 10% steer manure and flooded to ascertain field utility of the technique for on-site decontamination. Toxaphene residues were reduced from 63 to 23 ppm in 120 days, and some degradation activity still occurred up to 8 months after this single treatment.

  16. Resolution of contamination problems affecting laser surface certification inspection

    NASA Astrophysics Data System (ADS)

    Jackson, L. C.

    1982-03-01

    Contamination from particulate and organic residues which interfered, with the laser surface certification (LSC) inspection of some parts was found to come from three sources: particulate and organic residues from polishing compounds; organic films from cleaning solvents; and particles and organic residues transferred from plastic fixtures used to process these parts. The manufacturing cleaning process was not effective in removing all polishing compound residues, and an extensive cleaning procedure was developed using two solvents in a multicycle ultrasonic/vapor degreasing procedure. Parts were then subjected to gas plasma cleaning which removed the organic films left by the solvent cleaning. Plastic and rubber materials were evaluated for their contamination transfer characteristics; a fluorocarbon elastomer was the least contaminating. Inspection data established the efficacy of the cleaning procedure. After design relaxation, a single stage ultrasonic vapor degreasing process was used to achieve product acceptance.

  17. Detection of shifts in microbial community structure and diversity in soil caused by copper contamination using amplified ribosomal DNA restriction analysis

    Microsoft Academic Search

    Eric Smit; Paula Leeflang; Karel Wernars

    1997-01-01

    Amplified ribosomal DNA restriction analysis (ARDRA) was used for assessing the effect of copper contamination on the microbial community in soil. ARDRA is a DNA fingerprinting technique based on PCR amplification of 16S ribosomal DNA using primers for conserved regions, followed by restriction enzyme digestions and agarose gel electrophoresis. This results in distinguishable fingerprints for different bacterial species. Microbial community

  18. Insights into biodegradation through depth-resolved microbial community functional and structural profiling of a crude-oil contaminant plume

    USGS Publications Warehouse

    Fahrenfeld, Nicole; Cozzarelli, Isabelle M.; Bailey, Zach; Pruden, Amy

    2014-01-01

    Small-scale geochemical gradients are a key feature of aquifer contaminant plumes, highlighting the need for functional and structural profiling of corresponding microbial communities on a similar scale. The purpose of this study was to characterize the microbial functional and structural diversity with depth across representative redox zones of a hydrocarbon plume and an adjacent wetland, at the Bemidji Oil Spill site. A combination of quantitative PCR, denaturing gradient gel electrophoresis, and pyrosequencing were applied to vertically sampled sediment cores. Levels of the methanogenic marker gene, methyl coenzyme-M reductase A (mcrA), increased with depth near the oil body center, but were variable with depth further downgradient. Benzoate degradation N (bzdN) hydrocarbon-degradation gene, common to facultatively anaerobic Azoarcus spp., was found at all locations, but was highest near the oil body center. Microbial community structural differences were observed across sediment cores, and bacterial classes containing known hydrocarbon degraders were found to be low in relative abundance. Depth-resolved functional and structural profiling revealed the strongest gradients in the iron-reducing zone, displaying the greatest variability with depth. This study provides important insight into biogeochemical characteristics in different regions of contaminant plumes, which will aid in improving models of contaminant fate and natural attenuation rates.

  19. Monitoring method for surface contamination caused by selected antineoplastic agents.

    PubMed

    Larson, R R; Khazaeli, M B; Dillon, H Kenneth

    2002-02-01

    A method of evaluating surface contamination caused by selected antineoplastic agents was studied. The antineoplastic agents tested were cyclophosphamide, ifosfamide, doxorubicin hydrochloride, fluorouracil, and paclitaxel. Each agent was reconstituted and prepared as a stock solution. A 0.1-mL portion of each solution was spread evenly over a 600-cm2 area of a stainless steel surface, a resin countertop surface, and a vinyl flooring surface. After drying, the surfaces were wiped with each of two types of commercially available wiping materials (What-man no. 42 filters and Kimberly-Clark Kimwipes). A blend of methanol, acetonitrile, and buffered water was used both as the wetting agent for wiping the surfaces and as a desorbing solution. The desorbate was analyzed for drug concentration by reverse-phase high-performance liquid chromatography (HPLC). Mean +/- S.D. percent total recovery ranged from 72.4% +/- 17.6% to 95.3% +/- 2.9% for the vinyl surface wiped with filters, 91.5% +/- 5.4% to 104.7% +/- 0.8% for the resin surface wiped with filters, 73.9% +/- 2.3% to 95.3% +/- 1.7% for the stainless steel surface wiped with filters, and 18.2% +/- 1.4% to 372.8% +/- 8.0% for the stainless steel surface wiped with Kimwipes. Results were best for ifosfamide and cyclophosphamide. Kimwipes were deemed ineffective for this monitoring method because an ingredient interfered with the quantitative analytical tests. A wipe-sampling, desorption, and HPLC method for monitoring surface contamination by selected antineoplastic agents was sufficiently accurate and sensitive to evaluate surfaces typically found in both the pharmacy and drug administration areas of oncology treatment facilities. PMID:11862639

  20. Characterisation of CFRP surface contamination by laser induced fluorescence

    NASA Astrophysics Data System (ADS)

    Malinowski, Pawel H.; Sawczak, Miroslaw; Wandowski, Tomasz; Ostachowicz, Wieslaw M.; Cenian, Adam

    2014-03-01

    The application of Carbon Fibre Reinforced Polymers (CFRP) in aeronautics has been increasing. The CFRP elements are joint using rivets and adhesive bonding. The reliability of the bonding limits the use of adhesive bonding for primary aircraft structures, therefore it is important to assess the bond quality. The performance of adhesive bonds depends on the physico-chemical properties of the adhered surfaces. This research is focused on characterization of surfaces before bonding. In-situ examination of large surface materials, determine the group of methods that are preferred. The analytical methods should be non-destructive, enabling large surface analysis in relatively short time. In this work a spectroscopic method was tested that can be potentially applied for surface analysis. Four cases of surface condition were investigated that can be encountered either in the manufacturing process or during aircraft service. The first case is related to contamination of CFRP surface with hydraulic fluid. This fluid reacts with water forming a phosphoric acid that can etch the CFRP. Second considered case was related to silicone-based release agent contamination. These agents are used during the moulding process of composite panels. Third case involved moisture content in CFRP. Moisture content lowers the adhesion quality and leads to reduced performance of CFRP resulting in reduced performance of the adhesive bond. The last case concentrated on heat damage of CFRP. It was shown that laser induced fluorescence method can be useful for non-destructive evaluation of CFRP surface and some of the investigated contaminants can be easily detected.

  1. Reactor surface contamination stabilization. Innovative technology summary report

    SciTech Connect

    NONE

    1998-11-01

    Contaminated surfaces, such as the face of a nuclear reactor, need to be stabilized (fixed) to avoid airborne contamination during decontamination and decommissioning activities, and to prepare for interim safe storage. The traditional (baseline) method of fixing the contamination has been to spray a coating on the surfaces, but ensuring complete coverage over complex shapes, such as nozzles and hoses, is difficult. The Hanford Site C Reactor Technology Demonstration Group demonstrated innovative technologies to assess stabilization properties of various coatings and to achieve complete coverage of complex surfaces on the reactor face. This demonstration was conducted in two phases: the first phase consisted of a series of laboratory assessments of various stabilization coatings on metal coupons. For the second phase, coatings that passed the laboratory tests were applied to the front face of the C Reactor and evaluated. The baseline coating (Rust-Oleum No. 769) and one of the innovative technologies did not completely cover nozzle assemblies on the reactor face, the most critical of the second-phase evaluation criteria. However, one of the innovative coating systems, consisting of a base layer of foam covered by an outer layer of a polymeric film, was successful. The baseline technology would cost approximately 33% as much as the innovative technology cost of $64,000 to stabilize an entire reactor face (196 m{sup 2} or 2116 ft{sup 2}) with 2,004 nozzle assemblies, but the baseline system failed to provide complete surface coverage.

  2. Microbial Reduction on Eggshell Surfaces by the use of Hydrogen Peroxide and Ultraviolet Light

    E-print Network

    Gottselig, Steven Michael

    2011-10-21

    MICROBIAL REDUCTION ON EGGSHELL SURFACES BY THE USE OF HYDROGEN PEROXIDE AND ULTRAVIOLET LIGHT A Thesis by STEVEN MICHAEL GOTTSELIG Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 2011 Major Subject: Poultry Science Microbial Reduction on Eggshell Surfaces by the Use of Hydrogen Peroxide and Ultraviolet Light Copyright 2011...

  3. Microbial Interactions Preventing Fungal Growth on Senescent and Necrotic Aerial Plant Surfaces

    Microsoft Academic Search

    William F. Pfender

    Although there is an extensive literature concerning many aspects of phyllosphere microbial ecology, only a small proportion\\u000a addresses senescent and necrotic aerial plant tissues. But microbial activity on these surfaces is important, in part because\\u000a the microflora there can interact with microbes on living plant surfaces (see Köhl and Fokkema, 1994; Fokkema, 1993). Furthermore, a consideration of the environment on

  4. Microbial Community Structure Responses to Long-Term Acid-Mine Drainage Contamination in a Coastal Salt Marsh

    NASA Astrophysics Data System (ADS)

    Moreau, J. W.; Zierenberg, R. A.; Banfield, J. F.

    2004-12-01

    Constructed wetlands for in situ bioremediation of metals and acid mine drainage (AMD) require the activity of sulfate-reducing bacteria (SRB) to sequester dissolved metals into metal-sulfide precipitates (e.g. Webb et al. 1998). Factors such as low pH and high dissolved [Cu] will constrain the growth of SRB (Sani et al. 2001). Unintentional stimulation of the growth of sulfuric acid-generating microbes, such as Thiomicrospira, would also decrease bioremediation efficiency. Few studies of natural wetlands under long-term forcing by AMD and metals have been performed. We characterized the microbial diversity, mineralogy and geochemistry of a contaminated salt marsh at the Richmond Field Station along the East San Francisco Bay. For over 50 years, this marsh has received pH ˜2, metal-rich groundwaters from near-surface pyrite tailings and paint and explosives manufacturers. Sediment cores (30-40 cm long) were taken from contaminated sites with pH ˜2 and ˜8. Whole-sediment analyses showed As, Cd, Cu, Se, Zn, and Pb are present at 100s of ppm (URS Corp. 2001). ICP-AES analyses of pore waters showed 10-50 ppb As. All cores contained fine-grained black muds and exhibited a noticeable sulfide odor. Transmission electron microscope studies of marsh sediments support the sequestration of metals into aggregates of nanocrystalline sulfides. Isotopic analyses of pore-water sulfate taken at several depths within cores of AMD pool (SMR-1) and tidal slough sediments (SM148-1) at pHs 2-3 and 7-8, respectively, all yielded significant negative ? 34S values (-25 to -35 ‰ ) consistent with bacterial sulfate reduction. However, values of the upper 10 cm of SMR-1 are roughly 10 ‰ heavier than seawater and support a significant contribution of dissolved sulfate from direct oxidation of pyrite tailings. 16S gene clone libraries revealed significantly different microbial community structures in cores SMR-1 and SM148-1. Roughly 40% of the library from SMR-1 consisted of Thiomicrospira denitrificans (22%) and several other bacteria capable of oxidizing reduced sulfur species (18%). SRB were present (15%), however, and probably reflect contributions from core depths at which acidity is attenuated by tidal flushing. In contrast, SM148-1 contained ˜25% SRB, and aero- and halo-tolerant SRB were enriched from this core by cultivation. The dominance of Thiomicrospira and other sulfur-/sulfide-oxidizing bacteria, in combination with isotopic results, showed microbially-mediated pyrite oxidation in SMR-1. In contrast, Desulfobacterium spp. dominated the community in SM148-1 and reduced dissolved metals to near or below EPA action levels. References: Webb et al. 1998, J. Appl. Microbio., 84, 240-248; Sani et al. 2001, Applied Env. Microbio., 67, 4765-4772; URS Corp. 2001, Report 51.09967067.00.

  5. Water Sources and Their Protection from the Impact of Microbial Contamination in Rural Areas of Beijing, China

    PubMed Central

    Ye, Bixiong; Yang, Linsheng; Li, Yonghua; Wang, Wuyi; Li, Hairong

    2013-01-01

    Bacterial contamination of drinking water is a major public health problem in rural China. To explore bacterial contamination in rural areas of Beijing and identify possible causes of bacteria in drinking water samples, water samples were collected from wells in ten rural districts of Beijing, China. Total bacterial count, total coliforms and Escherichia coli in drinking water were then determined and water source and wellhead protection were investigated. The bacterial contamination in drinking water was serious in areas north of Beijing, with the total bacterial count, total coliforms and Escherichia coli in some water samples reaching 88,000 CFU/mL, 1,600 MPN/100 mL and 1,600 MPN/100 mL, respectively. Water source types, well depth, whether the well was adequately sealed and housed, and whether wellhead is above or below ground were the main factors influencing bacterial contamination levels in drinking water. The bacterial contamination was serious in the water of shallow wells and wells that were not closed, had no well housing or had a wellhead below ground level. The contamination sources around wells, including village dry toilets and livestock farms, were well correlated with bacterial contamination. Total bacterial counts were affected by proximity to sewage ditches and polluting industries, however, proximity to landfills did not influence the microbial indicators. PMID:23462436

  6. Microbial communities on flower surfaces act as signatures of pollinator visitation

    PubMed Central

    Ushio, Masayuki; Yamasaki, Eri; Takasu, Hiroyuki; Nagano, Atsushi J.; Fujinaga, Shohei; Honjo, Mie N.; Ikemoto, Mito; Sakai, Shoko; Kudoh, Hiroshi

    2015-01-01

    Microbes are easily dispersed from one place to another, and immigrant microbes might contain information about the environments from which they came. We hypothesized that part of the microbial community on a flower's surface is transferred there from insect body surfaces and that this community can provide information to identify potential pollinator insects of that plant. We collected insect samples from the field, and found that an insect individual harbored an average of 12.2 × 105 microbial cells on its surface. A laboratory experiment showed that the microbial community composition on a flower surface changed after contact with an insect, suggesting that microbes are transferred from the insect to the flower. Comparison of the microbial fingerprint approach and direct visual observation under field condition suggested that the microbial community on a flower surface could to some extent indicate the structure of plant–pollinator interactions. In conclusion, species-specific insect microbial communities specific to insect species can be transferred from an insect body to a flower surface, and these microbes can serve as a “fingerprint” of the insect species, especially for large-bodied insects. Dispersal of microbes is a ubiquitous phenomenon that has unexpected and novel applications in many fields and disciplines. PMID:25733079

  7. Microbial communities on flower surfaces act as signatures of pollinator visitation.

    PubMed

    Ushio, Masayuki; Yamasaki, Eri; Takasu, Hiroyuki; Nagano, Atsushi J; Fujinaga, Shohei; Honjo, Mie N; Ikemoto, Mito; Sakai, Shoko; Kudoh, Hiroshi

    2015-01-01

    Microbes are easily dispersed from one place to another, and immigrant microbes might contain information about the environments from which they came. We hypothesized that part of the microbial community on a flower's surface is transferred there from insect body surfaces and that this community can provide information to identify potential pollinator insects of that plant. We collected insect samples from the field, and found that an insect individual harbored an average of 12.2 × 10(5) microbial cells on its surface. A laboratory experiment showed that the microbial community composition on a flower surface changed after contact with an insect, suggesting that microbes are transferred from the insect to the flower. Comparison of the microbial fingerprint approach and direct visual observation under field condition suggested that the microbial community on a flower surface could to some extent indicate the structure of plant-pollinator interactions. In conclusion, species-specific insect microbial communities specific to insect species can be transferred from an insect body to a flower surface, and these microbes can serve as a "fingerprint" of the insect species, especially for large-bodied insects. Dispersal of microbes is a ubiquitous phenomenon that has unexpected and novel applications in many fields and disciplines. PMID:25733079

  8. Characterization of the Deltaproteobacteria in Contaminated and Uncontaminated Surface Stream Sediments and Identification of Potential Mercury Methylators

    SciTech Connect

    Mosher, Jennifer J [ORNL; Vishnivetskaya, Tatiana A [ORNL; Elias, Dwayne A [ORNL; Podar, Mircea [ORNL; Brooks, Scott C [ORNL; Brown, Steven D [ORNL; Brandt, Craig C [ORNL; Palumbo, Anthony Vito [ORNL

    2012-01-01

    Microbial communities were examined in surface stream sediments at five contaminated sites and one control site near Oak Ridge, TN in order to identify bacteria that could be contributing to mercury methylation. The phylogenetic composition of the sediment bacterial community was examined over three quarterly sampling periods (36 samples) using 16s rRNA pyrosequencing. Only 3064 sequences (0.85 % of the total community) were identified as Deltaproteobacteria by the RDP classifier at the 99% confidence threshold. Constrained ordination techniques indicated significant positive correlations between Desulfobulbus spp., Desulfonema spp. and Desulfobacca spp. and methyl mercury concentrations in the contaminated sites. On the contrary, the distribution of organisms related to Byssovorax was significantly correlated to inorganic carbon, nitrate and uranium concentrations. Overall, the abundance and richness of Deltaproteobacteria sequences were higher in the sediments of the site, while the majority of the members present at the contaminated sites were either known metal reducers/methylators or metal tolerant species.

  9. Surface scattering characteristics and the measurement of particulate contamination

    NASA Technical Reports Server (NTRS)

    Carosso, Paolo A.; Carosso, Nancy J. P.

    1986-01-01

    Surface scattering measurement techniques can be adopted for use in spacecraft contamination control programs. A witness mirror measurement program was developed and implemented for the NASA Cosmic Background Explorer (COBE) spacecraft. Scattering measurements were obtained before and after a qualification level vibration test for several COBE prototype instruments. The measurements indicate that a significant amount of particle redistribution occurred during the vibration test. The methodology used and the results obtained from this monitoring program are discussed.

  10. Catalytic surface effects on contaminated space shuttle tile in a dissociated nitrogen stream

    NASA Technical Reports Server (NTRS)

    Flowers, O. L.; Stewart, D. A.

    1985-01-01

    Visual inspection revealed contamination on the surface of tiles removed from the lower section of the space shuttle orbiter after the second flight of Columbia (STS-2). Possible sources of this contamination and the effect on surface catalycity are presented.

  11. A comparative review of optical surface contamination assessment techniques

    NASA Technical Reports Server (NTRS)

    Heaney, James B.

    1987-01-01

    This paper will review the relative sensitivities and practicalities of the common surface analytical methods that are used to detect and identify unwelcome adsorbants on optical surfaces. The compared methods include visual inspection, simple reflectometry and transmissiometry, ellipsometry, infrared absorption and attenuated total reflectance spectroscopy (ATR), Auger electron spectroscopy (AES), scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS), and mass accretion determined by quartz crystal microbalance (QCM). The discussion is biased toward those methods that apply optical thin film analytical techniques to spacecraft optical contamination problems. Examples are cited from both ground based and in-orbit experiments.

  12. Enhancement and inhibition of microbial activity in hydrocarbon- contaminated arctic soils: Implications for nutrient-amended bioremediation

    USGS Publications Warehouse

    Braddock, J.F.; Ruth, M.L.; Catterall, P.H.; Walworth, J.L.; McCarthy, K.A.

    1997-01-01

    Bioremediation is being used or proposed as a treatment option at many hydrocarbon-contaminated sites. One such site is a former bulk-fuel storage facility near Barrow, AK, where contamination persists after approximately 380 m3 of JP-5 was spilled in 1970. The soil at the site is primarily coarse sand with low organic carbon (<1%) end low moisture (1-3%) contents. We examined the effects of nutrient additions on microorganisms in contaminated soil from this site in laboratory microcosms and in mesocosms incubated for 6 weeks in the field. Nitrogen was the major limiting nutrient in this system, but microbial populations and activity were maximally enhanced by additions of both nitrogen and phosphorus. When nutrients were added to soil in the field at three levels of N:P (100:45, 200:90, and 300:135 mg/kg soil), the greatest stimulation in microbial activity occurred at the lowest, rather than the highest, level of nutrient addition. The total soil-water potentials ranged from -2 to -15 bar with increasing levels of fertilizer. Semivolatile hydrocarbon concentrations declined significantly only in the soils treated at the low fertilizer level. These results indicate that an understanding of nutrient effects at a specific site is essential for successful bioremediation.Bioremediation is being used or proposed as a treatment option at many hydrocarbon-contaminated sites. One such site is a former bulk-fuel storage facility near Barrow, AK, where contamination persists after approximately 380 m3 of JP-5 was spilled in 1970. The soil at the site is primarily coarse sand with low organic carbon (<1%) and low moisture (1-3%) contents. We examined the effects of nutrient additions on microorganisms in contaminated soil from this site in laboratory microcosms and in mesocosms incubated for 6 weeks in the field. Nitrogen was the major limiting nutrient in this system, but microbial populations and activity were maximally enhanced by additions of both nitrogen and phosphorus. When nutrients were added to soil in the field at three levels of N:P (100:45, 200:90, and 300:135 mg/kg soil), the greatest stimulation in microbial activity occurred at the lowest, rather than the highest, level of nutrient addition. The total soil-water potentials ranged from -2 to -15 bar with increasing levels of fertilizer. Semi-volatile hydrocarbon concentrations declined significantly only in the soils treated at the low fertilizer level. These results indicate that an understanding of nutrient effects at a specific site is essential for successful bioremediation.

  13. [Effects of Festuca arundinacea on the microbial community in crude oil-contaminated saline-alkaline soil].

    PubMed

    Li, Xin; Zhang, Hui-Hui; Yue, Bing-Bing; Xu, Nan; Zhu, Wen-Xu; Hu, Ju-Wei; Sun, Guang-Yu

    2012-12-01

    By using the routine soil physical and chemical analysis methods and the Biolog technique, this paper studied the effects of Festuca arundinacea growth on the pH value, total salt content, and microbial community in the rhizosphere of crude dil-contaminated saline-alkaline soil in Songnen Plain of Northeast China. Crude oil contamination resulted in the increases of average well color development (AWCD), Shannon index (H), and carbon source utilization richness index (S), and altered the utilization patterns of carbon sources by the microbes. F. arundinacea had greater potential to remediate crude oil-contaminated soil. This plant could decrease the soil pH and soil total petroleum hydrocarbon (TPH) content, and increase the soil water content. The AWCD and S in F. arundinacea rhizosphere soil were obviously higher than those in the soil of naked land, providing a suitable environment for the growth and development of rhizosphere soil microbes. PMID:23479885

  14. Explosive Contamination from Substrate Surfaces: Differences and Similarities in Contamination Techniques Using RDX and C-4

    NASA Astrophysics Data System (ADS)

    Miller, C. J.; Yoder, T. S.

    2010-06-01

    Explosive trace detection equipment has been deployed to airports for more than a decade. During this time, the need for standardized procedures and calibrated trace amounts for ensuring that the systems are operating properly and detecting the correct explosive has been apparent but a standard representative of a fingerprint has been elusive. Standards are also necessary to evaluate instrumentation in the laboratories during development and prior to deployment to determine sample throughput, probability of detection, false positive/negative rates, ease of use by operator, mechanical and/or software problems that may be encountered, and other pertinent parameters that would result in the equipment being unusable during field operations. Since many laboratories do not have access to nor are allowed to handle explosives, the equipment is tested using techniques aimed at simulating the actual explosives fingerprint. This laboratory study focused on examining the similarities and differences in three different surface contamination techniques that are used to performance test explosive trace detection equipment in an attempt to determine how effective the techniques are at replicating actual field samples and to offer scenarios where each contamination technique is applicable. The three techniques used were dry transfer deposition of standard solutions using the Transportation Security Laboratory’s (TSL) patented dry transfer techniques (US patent 6470730), direct deposition of explosive standards onto substrates, and fingerprinting of actual explosives onto substrates. RDX was deposited on the surface of one of five substrates using one of the three different deposition techniques. The process was repeated for each substrate type using each contamination technique. The substrate types used were: 50% cotton/50% polyester as found in T-shirts, 100% cotton with a smooth surface such as that found in a cotton dress shirt, 100% cotton on a rough surface such as that found on canvas or denim, suede leather such as might be found on jackets, purses, or shoes, and painted metal obtained from a car hood at a junk yard. The samples were not pre-cleaned prior to testing and contained sizing agents, and in the case of the metal, oil and dirt. The substrates were photographed using a Zeiss Discover V12 stereoscope with Axiocam ICc1 3 megapixel digital camera to determine the difference in the crystalline structure and surface contamination in an attempt to determine differences and similarities associated with current contamination deposition techniques. Some samples were analyzed using scanning electron microscopy (SEM) and some were extracted and analyzed with high performance liquid chromatography (HPLC) or gas chromatography with an electron capture detector (GC-ECD) to quantify the data.

  15. Microbial diversity in a hydrocarbon- and chlorinated-solvent- contaminated aquifer undergoing intrinsic bioremediation

    USGS Publications Warehouse

    Dojka, M.A.; Hugenholtz, P.; Haack, S.K.; Pace, N.R.

    1998-01-01

    A culture-independent molecular phylogenetic approach was used to survey constituents of microbial communities associated with an aquifer contaminated with hydrocarbons (mainly jet fuel) and chlorinated solvents undergoing intrinsic bioremediation. Samples were obtained from three redox zones: methanogenic, methanogenic-sulfate reducing, and iron or sulfate reducing. Small-subunit rRNA genes were amplified directly from aquifer material DNA by PCR with universally conserved or Bacteria- or Archaea-specific primers and were cloned. A total of 812 clones were screened by restriction fragment length polymorphisms (RFLP), approximately 50% of which were unique. All RFLP types that occurred more than once in the libraries, as well as many of the unique types, were sequenced. A total of 104 (94 bacterial and 10 archaeal) sequence types were determined. Of the 94 bacterial sequence types, 10 have no phylogenetic association with known taxonomic divisions and are phylogenetically grouped in six novel division level groups (candidate divisions WS1 to WS6); 21 belong to four recently described candidate divisions with no cultivated representatives (OPS, OP8, OP10, and OP11); and 63 are phylogenetically associated with 10 well-recognized divisions. The physiology of two particularly abundant sequence types obtained from the methanogenic zone could be inferred from their phylogenetic association with groups of microorganisms with a consistent phenotype. One of these sequence types is associated with the genus Syntrophus; Syntrophus spp. produce energy from the anaerobic oxidation of organic acids, with the production of acetate and hydrogen. The organism represented by the other sequence type is closely related to Methanosaeta spp., which are known to be capable of energy generation only through aceticlastic methanogenesis. We hypothesize, therefore, that the terminal step of hydrocarbon degradation in the methanogenic zone of the aquifer is aceticlastic methanogenesis and that the microorganisms represented by these two sequence types occur in syntrophic association.

  16. Versatile microbial surface-display for environmental remediation and biofuels production

    SciTech Connect

    Wu, Cindy H.; Mulchandani, Ashok; Chen, wilfred

    2008-02-14

    Surface display is a powerful technique that utilizes natural microbial functional components to express proteins or peptides on the cell exterior. Since the reporting of the first surface-display system in the mid-1980s, a variety of new systems have been reported for yeast, Gram-positive and Gram-negative bacteria. Non-conventional display methods are emerging, eliminating the generation of genetically modified microorganisms. Cells with surface display are used as biocatalysts, biosorbents and biostimulants. Microbial cell-surface display has proven to be extremely important for numerous applications ranging from combinatorial library screening and protein engineering to bioremediation and biofuels production.

  17. Impact of Substratum Surface on Microbial Community Structure and Treatment Performance in Biological Aerated Filters

    PubMed Central

    Kim, Lavane; Pagaling, Eulyn; Zuo, Yi Y.

    2014-01-01

    The impact of substratum surface property change on biofilm community structure was investigated using laboratory biological aerated filter (BAF) reactors and molecular microbial community analysis. Two substratum surfaces that differed in surface properties were created via surface coating and used to develop biofilms in test (modified surface) and control (original surface) BAF reactors. Microbial community analysis by 16S rRNA gene-based PCR-denaturing gradient gel electrophoresis (DGGE) showed that the surface property change consistently resulted in distinct profiles of microbial populations during replicate reactor start-ups. Pyrosequencing of the bar-coded 16S rRNA gene amplicons surveyed more than 90% of the microbial diversity in the microbial communities and identified 72 unique bacterial species within 19 bacterial orders. Among the 19 orders of bacteria detected, Burkholderiales and Rhodocyclales of the Betaproteobacteria class were numerically dominant and accounted for 90.5 to 97.4% of the sequence reads, and their relative abundances in the test and control BAF reactors were different in consistent patterns during the two reactor start-ups. Three of the five dominant bacterial species also showed consistent relative abundance changes between the test and control BAF reactors. The different biofilm microbial communities led to different treatment efficiencies, with consistently higher total organic carbon (TOC) removal in the test reactor than in the control reactor. Further understanding of how surface properties affect biofilm microbial communities and functional performance would enable the rational design of new generations of substrata for the improvement of biofilm-based biological treatment processes. PMID:24141134

  18. Effects of Nitrate Exposure on the Functional Structure of a Microbial Community in a Uranium-contaminated Aquifer

    SciTech Connect

    Van Nostrand, Joy; Waldron, P.; Wu, W.; Zhou, B.; Wu, Liyou; Deng, Ye; Carley, J.; He, Zhili; Gu, B.; Luo, J.; Criddle, C.; Jardine, P.; Hazen, Terry; Zhou, Jizhong

    2010-05-17

    Increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity are three main environmental changes occurring on a global scale. The BioCON (Biodiversity, CO2, and Nitrogen) ecological experiment site at the University of Minnesota's Cedar Creek Ecosystem Science Reserve started in 1997, to better understand how these changes would affect soil systems. To understand how increasing nitrogen deposition affects the microbial community diversity, heterogeneity, and functional structure impact soil microbial communities, 12 samples were collected from the BioCON plots in which nitrogenous fertilizer was added to simulate the effect of increasing nitrogen deposition and 12 samples from without added fertilizer. DNA from the 24 samples was extracted using a freeze-grind protocol, amplified, labeled with a fluorescent dye, and then hybridized to GeoChip, a functional gene array containing probes for genes involved in N, S and C cycling, metal resistance and organic contaminant degradation. Detrended correspondence analysis (DCA) of all genes detected was performed to analyze microbial community patterns. The first two axes accounted for 23.5percent of the total variation. The samples fell into two major groups: fertilized and non-fertilized, suggesting that nitrogenous fertilizer had a significant impact on soil microbial community structure and diversity. The functional gene numbers detected in fertilized samples was less that detected in non-fertilizer samples. Functional genes involving in the N cycling were mainly discussed.

  19. GeoChip-based analysis of microbial functional gene diversity in a landfill leachate-contaminated aquifer

    USGS Publications Warehouse

    Lu, Zhenmei; He, Zhili; Parisi, Victoria A.; Kang, Sanghoon; Deng, Ye; Van Nostrand, Joy D.; Masoner, Jason R.; Cozzarelli, Isabelle M.; Suflita, Joseph M.; Zhou, Jizhong

    2012-01-01

    The functional gene diversity and structure of microbial communities in a shallow landfill leachate-contaminated aquifer were assessed using a comprehensive functional gene array (GeoChip 3.0). Water samples were obtained from eight wells at the same aquifer depth immediately below a municipal landfill or along the predominant downgradient groundwater flowpath. Functional gene richness and diversity immediately below the landfill and the closest well were considerably lower than those in downgradient wells. Mantel tests and canonical correspondence analysis (CCA) suggested that various geochemical parameters had a significant impact on the subsurface microbial community structure. That is, leachate from the unlined landfill impacted the diversity, composition, structure, and functional potential of groundwater microbial communities as a function of groundwater pH, and concentrations of sulfate, ammonia, and dissolved organic carbon (DOC). Historical geochemical records indicate that all sampled wells chronically received leachate, and the increase in microbial diversity as a function of distance from the landfill is consistent with mitigation of the impact of leachate on the groundwater system by natural attenuation mechanisms.

  20. Influence of slaughter, fabrication and storage conditions on the microbial flora and shelf-life of vacuum-packaged steaks

    E-print Network

    Chandran, Sasi Kantha

    1984-01-01

    to limit microbial contamination of the carcass and restrict further microbiological contamination and growth during processing and subsequent storage. The microbial contamination of a carcass usually is attributed to less than optimum hygi eni c... through contact with contaminated utensils, equipment surfaces, clothes and hands of workers. The objectives of the present study are: I. To determine the effect of strict hygienic slaughter vs. conventional slaughter on the microbial count...

  1. A Optical Probe of Thin Film and Surface Contamination Based on Surface Plasmon Resonance.

    NASA Astrophysics Data System (ADS)

    Wang, Ran-Hong Raymond

    1990-01-01

    The microcontamination of optical surfaces or optical thin films affects many of their properties. In this work, we investigated several measurement systems to detect many types of surface contamination of coatings based on the surface plasmon resonance (SPR) phenomenon. The attenuated total reflection (ATR) coupling, also known as the Kretschmann configuration, excited the nonradiative surface plasmon wave for SPR measurement. Several microcontamination layers thinner than 10 nm were studied. The results showed that in all the cases SPR curves shifted to larger incident angles. From the amount of angle shift, the thickness of contamination was determined with a sensitivity of as little as one angstrom. The optical constants of those contamination layers were also derived. The shifts of the SPR curves served as an index for the efficiency of cleaning processes. It was found that the contamination by moisture can be removed with Iso-propyl alcohol by the ultrasonic cleaning process, while acetone was the more effective solvent in removing the contamination left by strippable coating residue show that the contamination layer was roughened by ultrasonic cleaning. In studies of island-like discontinuous thin layers of Ag, Al, and MgF_2, we found that the refractive index of MgF_2, a dielectric film material, slightly decreased as the thickness decreased, but for discontinuous metal films, the optical constants changed rapidly and became more dielectric in nature. Direct detection of contamination by coating processes in a small vacuum chamber was also carried out. In a chamber with high backstreaming from a diffusion pump, a broad SPR curve for an Ag film revealed obvious optical constant changes. Measuring and comparing the shift indicates that a significant amount of contamination was occurring right after the coating was completed. This suggests that for good evaporated optical thin films, it is important to have a more tightly controlled evaporation process. Finally, particulate, as well as layered, contamination can also be measured. A radiative SPR wave was generated by illuminating a contaminated surface. Similar radiative SPR waves also can be observed by adding a rough contaminant layer on an Ag film.

  2. Microbial sewage contamination associated with Superstorm Sandy flooding in New York City

    NASA Astrophysics Data System (ADS)

    O'Mullan, G.; Dueker, M.; Sahajpal, R.; Juhl, A. R.

    2013-05-01

    The lower Hudson River Estuary commonly experiences degraded water quality following precipitation events due to the influence of combined sewer overflows. During Super-storm Sandy large scale flooding occurred in many waterfront areas of New York City, including neighborhoods bordering the Gowanus Canal and Newtown Creek Superfund sites known to frequently contain high levels of sewage associated bacteria. Water, sediment, and surface swab samples were collected from Newtown Creek and Gowanus Canal flood impacted streets and basements in the days following the storm, along with samples from the local waterways. Samples were enumerated for the sewage indicating bacterium, Enterococcus, and DNA was extracted and amplified for 16S ribosomal rRNA gene sequence analysis. Waterways were found to have relatively low levels of sewage contamination in the days following the storm. In contrast, much higher levels of Enterococci were detected in basement and storm debris samples and these bacteria were found to persist for many weeks in laboratory incubations. These data suggest that substantial sewage contamination occurred in some flood impacted New York City neighborhoods and that the environmental persistence of flood water associated microbes requires additional study and management attention.

  3. Contamination of ground water, surface water, and soil, and evaluation of selected ground-water pumping alternatives in the Canal Creek area of Aberdeen Proving Ground, Maryland

    USGS Publications Warehouse

    Lorah, Michelle M.; Clark, Jeffrey S.

    1996-01-01

    Chemical manufacturing, munitions filling, and other military-support activities have resulted in the contamination of ground water, surface water, and soil in the Canal Creek area of Aberdeen Proving Ground, Maryland. Chlorinated volatile organic compounds, including 1,1,2,2-tetrachloroethane and trichloroethylene, are widespread ground-water contaminants in two aquifers that are composed of unconsolidated sand and gravel. Distribution and fate of chlorinated organic compounds in the ground water has been affected by the movement and dissolution of solvents in their dense immiscible phase and by microbial degradation under anaerobic conditions. Detection of volatile organic contaminants in adjacent surface water indicates that shallow contaminated ground water discharges to surface water. Semivolatile organic compounds, especially polycyclic aromatic hydrocarbons, are the most prevalent organic contaminants in soils. Various trace elements, such as arsenic, cadmium, lead, and zinc, were found in elevated concentrations in ground water, surface water, and soil. Simulations with a ground-water-flow model and particle tracker postprocessor show that, without remedial pumpage, the contaminants will eventually migrate to Canal Creek and Gunpowder River. Simulations indicate that remedial pumpage of 2.0 million gallons per day from existing wells is needed to capture all particles originating in the contaminant plumes. Simulated pumpage from offsite wells screened in a lower confined aquifer does not affect the flow of contaminated ground water in the Canal Creek area.

  4. Characterization of Archaeal Community in Contaminated and Uncontaminated Surface Stream Sediments

    PubMed Central

    Porat, Iris; Vishnivetskaya, Tatiana A.; Mosher, Jennifer J.; Brandt, Craig C.; Yang, Zamin K.; Brooks, Scott C.; Liang, Liyuan; Drake, Meghan M.; Podar, Mircea; Brown, Steven D.

    2010-01-01

    Archaeal communities from mercury and uranium-contaminated freshwater stream sediments were characterized and compared to archaeal communities present in an uncontaminated stream located in the vicinity of Oak Ridge, TN, USA. The distribution of the Archaea was determined by pyrosequencing analysis of the V4 region of 16S rRNA amplified from 12 streambed surface sediments. Crenarchaeota comprised 76% of the 1,670 archaeal sequences and the remaining 24% were from Euryarchaeota. Phylogenetic analysis further classified the Crenarchaeota as a Freshwater Group, Miscellaneous Crenarchaeota group, Group I3, Rice Cluster VI and IV, Marine Group I and Marine Benthic Group B; and the Euryarchaeota into Methanomicrobiales, Methanosarcinales, Methanobacteriales, Rice Cluster III, Marine Benthic Group D, Deep Sea Hydrothermal Vent Euryarchaeota 1 and Eury 5. All groups were previously described. Both hydrogen- and acetate-dependent methanogens were found in all samples. Most of the groups (with 60% of the sequences) described in this study were not similar to any cultivated isolates, making it difficult to discern their function in the freshwater microbial community. A significant decrease in the number of sequences, as well as in the diversity of archaeal communities was found in the contaminated sites. The Marine Group I, including the ammonia oxidizer Nitrosopumilus maritimus, was the dominant group in both mercury and uranium/nitrate-contaminated sites. The uranium-contaminated site also contained a high concentration of nitrate, thus Marine Group I may play a role in nitrogen cycle. Electronic supplementary material The online version of this article (doi:10.1007/s00248-010-9734-2) contains supplementary material, which is available to authorized users. PMID:20725722

  5. Microbial contamination of groundwater at small community water supplies in Finland.

    PubMed

    Pitkänen, Tarja; Karinen, Päivi; Miettinen, Ilkka T; Lettojärvi, Heidi; Heikkilä, Annika; Maunula, Reetta; Aula, Vesa; Kuronen, Henry; Vepsäläinen, Asko; Nousiainen, Liina-Lotta; Pelkonen, Sinikka; Heinonen-Tanski, Helvi

    2011-06-01

    The raw water quality and associations between the factors considered as threats to water safety were studied in 20 groundwater supplies in central Finland in 2002-2004. Faecal contaminations indicated by the appearance of Escherichia coli or intestinal enterococci were present in five small community water supplies, all these managed by local water cooperatives. Elevated concentrations of nutrients in raw water were linked with the presence of faecal bacteria. The presence of on-site technical hazards to water safety, such as inadequate well construction and maintenance enabling surface water to enter into the well and the insufficient depth of protective soil layers above the groundwater table, showed the vulnerability of the quality of groundwater used for drinking purposes. To minimize the risk of waterborne illnesses, the vulnerable water supplies need to be identified and appropriate prevention measures such as disinfection should be applied. PMID:21809781

  6. Sorption of organic compounds to microbial extracellular polymers: Potential vector for bioaccumulation of sediment-associated contaminants

    SciTech Connect

    Schlekat, C.E.; Decho, A.W.; Chandler, G.T. [Univ. of South Carolina, Columbia, SC (United States)

    1995-12-31

    Microbial extracellular polymeric substances (EPS) in the form of organic carbon coatings are ubiquitous features of marine surficial sediments and suspended particulate matter. Consisting primarily of polysaccharides, EPS are produced by bacteria for adhesion to substrata, to bind essential nutrients, and to protect bacterial cells from exogenous stressors, including toxic trace metals. EPS particulate coatings are easily digested by marine particle-ingesting invertebrates. Additionally, these organisms directly assimilate dissolved organic material and trace metals adsorbed to EPS-coated particulate. The capacity of EPS-coated particulate matter to serve as a vector for bioaccumulation of sediment-associated contaminants has not been addressed. As a step, the authors measured adsorption of selected organic contaminants by EPS-coated hydrated silica particles (mean diameter = 30 {micro}m). Radio-labeled organic contaminants, including benzo(a)pyrene, hexachlorobiphenyl, and the pesticides azinphosmethyl and chlorpyrifos were associated with coated particles in seawater under constant pH, salinity, temperature, and Eh. Mixtures were incubated until equilibrium was approximated, at which point partitioning between seawater and particulate was determined for each particulate/contaminant combination. The organic compounds exhibited a range of log K{sub ow} from 2.6 (azinphosmethyl) to 6.7 (hexachlorobiphenyl), which allowed for quantification of the relationship between partitioning and contaminant hydrophobicity. Effects of differential EPS composition were evaluated by measuring binding affinity of hexachlorobiphenyl particles coated with EPS obtained from three bacterial species which produce EPS with unique compositional attributes: Azotobacter vinelandii, Leuconostoc mesenteroides, and Pseudomonas atlantica.

  7. Evaluation of bacterial contamination rate of the anterior chamber during phacoemulsification surgery using an automated microbial detection system

    PubMed Central

    Kocak, Ibrahim; Kocak, Funda; Teker, Bahri; Aydin, Ali; Kaya, Faruk; Baybora, Hakan

    2014-01-01

    AIM To assess the incidence of anterior chamber bacterial contamination during phacoemulsification surgery using an automated microbial detection system (BacT/Alert). METHODS Sixty-nine eyes of 60 patients who had uneventful phacoemulsification surgery, enrolled in this prospective study. No prophylactic topical or systemic antibiotics were used before surgery. After antisepsis with povidone-iodine, two intraoperative anterior chamber aqueous samples were obtained, the first whilst entering anterior chamber, and the second at the end of surgery. BacT/Alert culture system was used to detect bacterial contamination in the aqueous samples. RESULTS Neither aqueous samples obtained at the beginning nor conclusion of the surgery was positive for microorganisms on BacT/Alert culture system. The rate of bacterial contamination during surgery was 0%. None of the eyes developed acute-onset endophthalmitis after surgery. CONCLUSION In this study, no bacterial contamination of anterior chamber was observed during cataract surgery. This result shows that meticulous surgical preparation and technique can prevent anterior chamber contamination during phacoemulsification cataract surgery. PMID:25161944

  8. Influence of Petroleum Hydrocarbon Contamination on Microalgae and Microbial Activities in a Long-Term Contaminated Soil

    Microsoft Academic Search

    M. Megharaj; I. Singleton; N. C. McClure; R. Naidu

    2000-01-01

    .   Petroleum hydrocarbons are widespread environmental pollutants. Although biodegradation of petroleum hydrocarbons has been\\u000a the subject of numerous investigations, information on their toxicity to microorganisms in soil is limited, with virtually\\u000a no work conducted on soil algae. We carried out a screening experiment for total petroleum hydrocarbons (TPH) and their toxicity\\u000a to soil algal populations, microbial biomass, and soil enzymes

  9. Electrochemical detection of harmful algae and other microbial contaminants in coastal waters using hand-held biosensors.

    PubMed

    LaGier, Michael J; Fell, Jack W; Goodwin, Kelly D

    2007-06-01

    Standard methods to identify microbial contaminants in the environment are slow, laborious, and can require specialized expertise. This study investigated electrochemical detection of microbial contaminants using commercially available, hand-held instruments. Electrochemical assays were developed for a red tide dinoflagellate (Karenia brevis), fecal-indicating bacteria (Enterococcus spp.), markers indicative of human sources of fecal pollution (human cluster Bacteroides and the esp gene of Enterococcus faecium), bacterial pathogens (Escherichia coli 0157:H7, Salmonella spp., Campylobacter jejuni, Staphylococcus aureus), and a viral pathogen (adenovirus). For K. brevis, two assay formats (Rapid PCR-Detect and Hybrid PCR-Detect) were tested and both provided detection limits of 10 genome equivalents for DNA isolated from K. brevis culture and amplified by PCR. Sensitivity with coastal water samples was sufficient to detect K. brevis that was "present" (microbial contaminants and have the potential to be integrated into semi-automated detection platforms. PMID:17328925

  10. The influence of feedlot pen surface layers on microbial community structure and diversity.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The biological and chemical characteristics of feedyard pen surfaces have the potential to affect environmental conditions with respect to air and water quality. Little is known about feedyard pen surface chemistry and biology, especially that of the underlying microbial community structure. The f...

  11. Measurement of total hemispherical emissivity of contaminated mirror surfaces

    NASA Technical Reports Server (NTRS)

    Facey, T. A.; Nonnenmacher, A. L.

    1989-01-01

    The effects of dust contamination on the total hemispherical emissivity (THE) of a 1.5-inch-diameter Al/MgF2-coated telescope mirror are investigated experimentally. The THE is determined by means of cooling-rate measurements in the temperature range 10-14.5 C in a vacuum of 100 ntorr or better. Photographs and drawings of the experimental setup are provided, and results for 11 dust levels are presented in tables and graphs. It is shown that dust has a significant effect on THE, but the experimental losses are only about half those predicted for perfectly black dust in perfect thermal contact with the mirror surface.

  12. Natural arsenic contamination of Holocene alluvial aquifers by linked tectonic, weathering, and microbial processes

    E-print Network

    Fayek, Mostafa

    tectonic, geochemical, and biologic processes lead to natural arsenic contamination of groundwater As to groundwater under moderately reducing conditions. Components: 3380 words, 3 figures. Keywords: arsenic- crobiology of arsenic in the alluvial aquifers. Moreover, the widespread As contamination of groundwater

  13. Effect of surface treatment on the biocompatibility of microbial polyhydroxyalkanoates

    Microsoft Academic Search

    Xianshuang Yang; Kai Zhao; Guo-Qiang Chen

    2002-01-01

    The biocompatibility of microbial polyesters polyhydroxybutyrate (PHB) and poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) were evaluated in vitro. The mouse fibroblast cell line L929 was inoculated on films made of PHB, PHBHHx and their blends, polylactic acid (PLA) as control. It was found that the growth of the cells L929 was poor on PHB and PLA films. The viable cell number ranged from 8.8×102

  14. The Effects of Microbial Population on Phytoremediation of Petroleum Contaminated Soils Using Tall Fescue

    Microsoft Academic Search

    JAHANGIR ABEDI-KOUPAI; REZA EZZATIAN; MANOUCHEHR VOSSOUGHI-SHAVARI; SOHEILA YAGHMAEI; MEHDI BORGHEI

    Petroleum contamination of soil is a serious problem throughout the south of Tehran and Khuzestan province of Iran. Vegetation may play an important role in the biodegradation of toxic organic chemicals in soil. For petroleum compounds, the presence of rhizosphere microflora may accelerate biodegradation of the contaminants. In a greenhouse study, petroleum contaminated soils from sites around Tehran Refinery Planet

  15. EFFECTS OF ORGANIC AMENDMENTS ON MICROBIAL PROPERTIES IN LEAD-CONTAMINATED SOILS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Environmental Protection Agency lists more than 17,000 contaminated sites in the United States, many of which are contaminated with heavy metals including lead (Pb) and zinc (Zn). Lead contamination in soil has been shown to be a threat to human health and ecosystem functioning through adverse e...

  16. Microbial Contamination of Allende and Murchison Carbonaceous Chondrites; Developing a Protocol for Life Detection in Extraterrestrial Materials Using Biotechnology

    NASA Technical Reports Server (NTRS)

    Steele, A.; Whitby, C.; Griffin, C.; Toporski, J. K. W.; Westall, F.; Saunders, J. R.; McKay, D. S.

    2001-01-01

    The arguments used to refute the McKay et al., (1996) hypothesis of possible Martian life in ALH84001 failed to use contamination of the meteorite as a source. This has worrying implications for our ability to detect terrestrial microbiota in meteorites and therefore any potential extraterrestrial biosignatures in both meteorites and possible returned samples. We report on imaging and microbial culturing of both Allende and Murchison carbonaceous chondrites and on the use of molecular biology techniques on a sample of Allende. Contaminating fungi and bacteria were observed (in the case of Murchison) and cultured from both meteorites. DNA was successfully extracted and subsequent PCR showed the presence of both bacterial and fungal DNA although no Archaea were detected. These results show that it is possible to use molecular biological techniques on very small quantities (300 mg) of extraterrestrial material.

  17. EVALUATION OF CONSTRUCTED WETLAND AND RETENTION POND BMPS FOR ATTENUATING MICROBIAL CONTAMINANTS IN URBAN STORMWATER RUNOFF

    EPA Science Inventory

    This project investigated the use of constructed wetlands and retention ponds for decreasing microbial concentrations from urban stormwater runoff. Increased urbanization has resulted in a larger percentage of impervious areas which cause large quantities of stormwater runoff an...

  18. Epidemiological Investigation of Risk Factors for Microbial Contamination in Produce at the Preharvest Level

    E-print Network

    Park, Sangshin

    2013-11-15

    In the United States, the proportion of outbreaks of microbial foodborne illnesses associated with fresh produce has increased over the past decades. A large proportion of these outbreaks have been caused by enteric pathogens, including Listeria...

  19. Investigation of Microbial Populations in the Extremely Metal-Contaminated Coeur d'Alene River Sediments

    Microsoft Academic Search

    Gurdeep Rastogi; Sutapa Barua; Rajesh K. Sani; Brent M. Peyton

    The deposition of mine tailings generated from 125 years of sulfidic ore mining resulted in the enrichment of Coeur d'Alene\\u000a River (CdAR) sediments with significant amounts of toxic heavy metals. A review of literature suggests that microbial populations\\u000a play a pivotal role in the biogeochemical cycling of elements in such mining-impacted sedimentary environments. To assess\\u000a the indigenous microbial communities associated with

  20. Mobility and distribution of arsenic in contaminated mine soils and its effects on the microbial pool.

    PubMed

    Marabottini, R; Stazi, S R; Papp, R; Grego, S; Moscatelli, M C

    2013-10-01

    Three soils, coming from a former mining site and characterized by a different degree of pollution, were analysed in terms of Arsenic (As) content, using three different analytical approaches, and its distribution in various soil fractions. The effect of As on soil microbial biomass (size, respiration and microbial quotients) was also analysed. Total arsenic concentration between soil fractions was significantly different and ranged from 189 to 4357mgkg(-1), indicating a high level of pollution. Soil sequential fractioning showed that more than 60 percent of total As was bound to Fe-Al oxides, suggesting a minor availability and environmental risk regardless the total concentration of As in the sample. On the contrary, water soluble As fraction showed a significant difference among the three samples. The largest water soluble As concentration was found in the sample with intermediate total As amount. As far as microbial biomass is concerned, it was found that bioavailable As negatively impacted microbial metabolism in terms of basal and cumulative respiration, and microbial quotients, suggesting a strong selection within microbial pool. PMID:23856118

  1. Robotic Radionuclide Inspection and Mapping of Surface Contamination On Building Surfaces

    SciTech Connect

    Mauer, G.F.; Kawa, Ch. [Nevada Univ., Dept. of Mechanical Engineering, Las Vegas, NV (United States)

    2007-07-01

    The mapping of localized regions of radionuclide contamination in a building can be a time consuming and costly task. Humans moving hand-held radiation detectors over the target areas are subject to fatigue. A contamination map based on manual surveys can contain significant operator-induced inaccuracies. A Fanuc M16i light industrial robot has been configured for installation on a mobile aerial work platform, such as a tall forklift. When positioned in front of a surface, the robot can map the radiation levels over a surface area of up to 2 m by 2 m. The robot's end effector is a commercial alpha-beta radiation sensor, augmented with range and collision avoidance sensors to ensure operational safety as well as to maintain a constant gap between surface and radiation sensors. A graphical user interface guides the robot operator to position the robot at the desired wall segments, and to select an area for surveying. After the operator has entered the required parameters, the custom surveying software plans the scan sequence, alerts of any potential problems, such as unreachable singularities, and creates a contamination map of the surveyed region. Maps of multiple regions can be combined into a single map of the entire region. The survey data are stored in a data base file. In addition to automated surface scans, operators can manually select regions for further inspection, as well as control the end effector motion manually. In comparison to manual contamination surveys, the robotic approach is more accurate, reliable, and faster. (authors)

  2. Improved RDX detoxification with starch addition using a novel nitrogen-fixing aerobic microbial consortium from soil contaminated with explosives.

    PubMed

    Khan, Muhammad Imran; Yang, Jihoon; Yoo, Byungun; Park, Joonhong

    2015-04-28

    In this work, we developed and characterized a novel nitrogen-fixing aerobic microbial consortium for the complete detoxification of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Aerobic RDX biodegradation coupled with microbial growth and nitrogen fixation activity were effectively stimulated by the co-addition of starch and RDX under nitrogen limiting conditions. In the starch-stimulated nitrogen-fixing RDX degradative consortium, the RDX degradation activity was correlated with the xplA and nifH gene copy numbers, suggesting the involvement of nitrogen fixing populations in RDX biodegradation. Formate, nitrite, nitrate, and ammonia were detected as aerobic RDX degradation intermediates without the accumulation of any nitroso-derivatives or NDAB (4-nitro-2,4-diazabutanal), indicating nearly complete mineralization. Pyrosequencing targeting the bacterial 16S rRNA genes revealed that the Rhizobium, Rhizobacter and Terrimonas population increased as the RDX degradation activity increased, suggesting their involvement in the degradation process. These findings imply that the nitrogen-fixing aerobic RDX degrading consortium is a valuable microbial resource for improving the detoxification of RDX-contaminated soil or groundwater, especially when combined with rhizoremediation. PMID:25661171

  3. Environmental proteomics reveals early microbial community responses to biostimulation at a uranium- and nitrate-contaminated site

    SciTech Connect

    Chourey, Karuna [ORNL] [ORNL; Nissen, Silke [ORNL] [ORNL; Vishnivetskaya, T. [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Shah, Manesh B [ORNL] [ORNL; Pffifner, Susan [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Hettich, Robert {Bob} L [ORNL; Loeffler, Frank E [ORNL] [ORNL

    2013-01-01

    High performance mass spectrometry instrumentation coupled with improved protein extraction techniques enable metaproteomics to identify active members of soil and groundwater microbial communities. Metaproteomics workflows were applied to study the initial responses (i.e., 4 days post treatment) of the indigenous aquifer microbiota to biostimulation with emulsified vegetable oil (EVO) at a uranium-contaminated site. Members of the Betaproteobacteria (i.e., Dechloromonas, Ralstonia, Rhodoferax, Polaromonas, Delftia, Chromobacterium) and Firmicutes dominated the biostimulated aquifer community. Proteome characterization revealed distinct differences in protein expression between the microbial biomass collected from groundwater influenced by biostimulation and groundwater collected up-gradient of the EVO injection points. In particular, proteins involved in ammonium assimilation, EVO degradation, and polyhydroxybutyrate (PHB) granule formation were prominent following biostimulation. Interestingly, the atypical NosZ of a Dechloromonas sp. was highly expressed suggesting active nitrous oxide (N2O) respiration. c-type cytochromes were barely detected, as was citrate synthase, a biomarker for hexavalent uranium reduction activity, suggesting that metal reduction has not commenced 4 days post EVO delivery. Environmental metaproteomics identified microbial community responses to biostimulation and elucidated active pathways demonstrating the value of this technique for complementing nucleic acid-based approaches.

  4. GeoChip-based analysis of functional microbial communities in a bioreduced uranium-contaminated aquifer during reoxidation by oxygen

    SciTech Connect

    Van Nostrand, J.D.; Wu, W.-M.; Wu, L.; Deng, Y.; Carley, J.; Carroll, S.; He, Z.; Gu, B.; Luo, J.; Criddle, C. S.; Watson, D. B.; Jardine, P. M.; Tiedje, J. M.; Hazen, T. C.; Zhou, J.

    2009-07-15

    A pilot-scale system was established for in situ biostimulation of U(VI) reduction by ethanol addition at the US Department of Energy's (DOE's) Field Research Center (Oak Ridge, TN). After achieving U(VI) reduction, stability of the bioreduced U(IV) was evaluated under conditions of (i) resting (no ethanol injection), (ii) reoxidation by introducing dissolved oxygen (DO), and (iii) reinjection of ethanol. GeoChip, a functional gene array with probes for N, S and C cycling, metal resistance and contaminant degradation genes, was used for monitoring groundwater microbial communities. High diversity of all major functional groups was observed during all experimental phases. The microbial community was extremely responsive to ethanol, showing a substantial change in community structure with increased gene number and diversity after ethanol injections resumed. While gene numbers showed considerable variations, the relative abundance (i.e. percentage of each gene category) of most gene groups changed little. During the reoxidation period, U(VI) increased, suggesting reoxidation of reduced U(IV). However, when introduction of DO was stopped, U(VI) reduction resumed and returned to pre-reoxidation levels. These findings suggest that the community in this system can be stimulated and that the ability to reduce U(VI) can be maintained by the addition of electron donors. This biostimulation approach may potentially offer an effective means for the bioremediation of U(VI)-contaminated sites.

  5. Minimisation of microbial contamination for potential islet xenografts using specific pathogen-free pigs and a protected environment during tissue preparation.

    PubMed

    Gouin, E; Rivereau, A S; Darquy, S; Cariolet, R; Jestin, A; Reach, G; Sai, P

    1997-12-01

    One major risk of islet xenotransplantation is transmission of infections. We thus compared microbial contamination during preparation of islets from 4 pigs conventionally breeded and slaughtered or 8 specific pathogen free (SPF) pigs, and different environmental conditions during pancreas excision. Pancreas harvested in a slaughterhouse (for conventional pigs) or in a protected autopsy room (for SPF pigs) were soaked in betadine solution and submitted to enzymatic digestion with collagenase. Islets were purified on histopaque gradient with a COBE 2991 processor. For each step of the process, a 10 ml aliquot was harvested and microbial contamination was analysed. For all animals, contamination of livers, which were not soaked in betadine solution, was also examined. Analysis of livers from the 4 conventional pigs showed polymicrobial contaminations (1,122 +/- 841 CFU/mg) with several species of Staphylococcus, Streptococcus, Bacillus and Enterobacteriaceae. For these conventional pigs, soaking of pancreas in betadine solution and presence of antibiotics in all media decreased the pancreatic contamination compared to hepatic contamination, but were unable to suppress it, as transport solution and crude suspension obtained after the digestion step with collagenase showed persistent contamination (9.7 +/- 2.4 and 10.5 +/- 4 CFU/ml, respectively). After islet purification by histopaque gradient, no medium remained contaminated. During analysis of the 8 SPF pigs, no liver exhibited contamination. Analysis of medium from each preparation step showed complete absence of contamination for 7 pancreases. Only one contamination with Staphylococcus simulans was observed for one pancreas in transport solution (6 CFU/ml), and persisted in digestion medium (16 CFU/ml). Finally, all purified suspensions were completely sterile. In conclusion, breeding conditions of pig islet donors, and controlled environment for pancreas excision, considerably influence the risk of microbial contamination. In order to limit the risk, SPF pigs are a suitable and compulsory source of islets. PMID:9496562

  6. Bacterial adhesion to surfaces and microbial safety of fresh produce

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Consumption of fresh produce is a central component of a healthy diet. However, contamination of fresh and fresh-cut fruits and vegetables such as leafy greens, tomatoes, cantaloupes is a source of ongoing concern for consumers. Growers, packers, processors and retailers work to control the incidenc...

  7. MULTIPLE IMAGING TECHNIQUES DEMONSTRATE THE MANIPULATION OF SURFACES TO REDUCE BACTERIAL CONTAMINATION

    EPA Science Inventory

    Surface imaging techniques were combined to determine appropriate manipulation of technologically important surfaces for commercial applications. Stainless steel surfaces were engineered to reduce bacterial contamination, biofilm formation, and corrosion during product processing...

  8. Microbial metabolism and community structure in response to bioelectrochemically enhanced remediation of petroleum hydrocarbon-contaminated soil.

    PubMed

    Lu, Lu; Huggins, Tyler; Jin, Song; Zuo, Yi; Ren, Zhiyong Jason

    2014-04-01

    This study demonstrates that electrodes in a bioelectrochemical system (BES) can potentially serve as a nonexhaustible electron acceptor for in situ bioremediation of hydrocarbon contaminated soil. The deployment of BES not only eliminates aeration or supplement of electron acceptors as in contemporary bioremediation but also significantly shortens the remediation period and produces sustainable electricity. More interestingly, the study reveals that microbial metabolism and community structure distinctively respond to the bioelectrochemically enhanced remediation. Tubular BESs with carbon cloth anode (CCA) or biochar anode (BCA) were inserted into raw water saturated soils containing petroleum hydrocarbons for enhancing in situ remediation. Results show that total petroleum hydrocarbon (TPH) removal rate almost doubled in soils close to the anode (63.5-78.7%) than that in the open circuit positive controls (37.6-43.4%) during a period of 64 days. The maximum current density from the BESs ranged from 73 to 86 mA/m(2). Comprehensive microbial and chemical characterizations and statistical analyses show that the residual TPH has a strongly positive correlation with hydrocarbon-degrading microorganisms (HDM) numbers, dehydrogenase activity, and lipase activity and a negative correlation with soil pH, conductivity, and catalase activity. Distinctive microbial communities were identified at the anode, in soil with electrodes, and soil without electrodes. Uncommon electrochemically active bacteria capable of hydrocarbon degradation such as Comamonas testosteroni, Pseudomonas putida, and Ochrobactrum anthropi were selectively enriched on the anode, while hydrocarbon oxidizing bacteria were dominant in soil samples. Results from genus or phylum level characterizations well agree with the data from cluster analysis. Data from this study suggests that a unique constitution of microbial communities may play a key role in BES enhancement of petroleum hydrocarbons biodegradation in soils. PMID:24628095

  9. Further biogeochemical characterization of a trichloroethene-contaminated fractured dolomite aquifer: Electron source and microbial communities involved in reductive dechlorination

    USGS Publications Warehouse

    Hohnstock-Ashe, A. M.; Plummer, S.M.; Yager, R.M.; Baveye, P.; Madsen, E.L.

    2001-01-01

    A recent article presented geochemical and microbial evidence establishing metabolic adaptation to and in-situ reductive dechlorination of trichloroethene (TCE) in a fractured dolomite aquifer. This study was designed to further explore site conditions and microbial populations and to explain previously reported enhancement of reductive dechlorination by the addition of pulverized dolomite to laboratory microcosms. A survey of groundwater geochemical parameters (chlorinated ethenes, ethene, H2, CH4, DIC, DOC, and ??13C values for CH4, DIC, and DOC) indicated that in situ reductive dechlorination was ongoing and that an unidentified pool of organic carbon was contributing, likely via microbial respiration, to the large and relatively light onsite DIC pool. Petroleum hydrocarbons associated with the dolomite rock were analyzed by GC/MS and featured a characteristically low ??13C value. Straight chain hydrocarbons were extracted from the dolomite previously found to stimulate reductive dechlorination; these were particularly depleted in hexadecane (HD). Thus, we hypothesized that HD and related hydrocarbons might be anaerobically respired and serve both as the source of onsite DIC and support reductive dechlorination of TCE. Microcosms amended with pulverized dolomite demonstrated reductive dechlorination, whereas a combusted dolomite amendment did not. HD-amended microcosms were also inactive. Therefore, the stimulatory factor in the pulverized dolomite was heat labile, but that component was not HD. Amplified Ribosomal DNA Restriction Analysis (ARDRA) of the microbial populations in well waters indicated that a relatively low diversity, sulfur-transforming community outside the plume was shifted toward a high diversity community including Dehalococcoides ethenogenes-type microorganisms inside the zone of contamination. These observations illustrate biogeochemical intricacies of in situ reductive dechlorination reactions.

  10. Dynamics of microbial community composition and function during in situ bioremediation of a uranium-contaminated aquifer.

    PubMed

    Van Nostrand, Joy D; Wu, Liyou; Wu, Wei-Min; Huang, Zhijian; Gentry, Terry J; Deng, Ye; Carley, Jack; Carroll, Sue; He, Zhili; Gu, Baohua; Luo, Jian; Criddle, Craig S; Watson, David B; Jardine, Philip M; Marsh, Terence L; Tiedje, James M; Hazen, Terry C; Zhou, Jizhong

    2011-06-01

    A pilot-scale system was established to examine the feasibility of in situ U(VI) immobilization at a highly contaminated aquifer (U.S. DOE Integrated Field Research Challenge site, Oak Ridge, TN). Ethanol was injected intermittently as an electron donor to stimulate microbial U(VI) reduction, and U(VI) concentrations fell to below the Environmental Protection Agency drinking water standard (0.03 mg liter(-1)). Microbial communities from three monitoring wells were examined during active U(VI) reduction and maintenance phases with GeoChip, a high-density, comprehensive functional gene array. The overall microbial community structure exhibited a considerable shift over the remediation phases examined. GeoChip-based analysis revealed that Fe(III)-reducing bacterial (FeRB), nitrate-reducing bacterial (NRB), and sulfate-reducing bacterial (SRB) functional populations reached their highest levels during the active U(VI) reduction phase (days 137 to 370), in which denitrification and Fe(III) and sulfate reduction occurred sequentially. A gradual decrease in these functional populations occurred when reduction reactions stabilized, suggesting that these functional populations could play an important role in both active U(VI) reduction and maintenance of the stability of reduced U(IV). These results suggest that addition of electron donors stimulated the microbial community to create biogeochemical conditions favorable to U(VI) reduction and prevent the reduced U(IV) from reoxidation and that functional FeRB, SRB, and NRB populations within this system played key roles in this process. PMID:21498771

  11. Dynamics of Microbial Community Composition and Function during In Situ Bioremediation of a Uranium-Contaminated Aquifer?‡

    PubMed Central

    Van Nostrand, Joy D.; Wu, Liyou; Wu, Wei-Min; Huang, Zhijian; Gentry, Terry J.; Deng, Ye; Carley, Jack; Carroll, Sue; He, Zhili; Gu, Baohua; Luo, Jian; Criddle, Craig S.; Watson, David B.; Jardine, Philip M.; Marsh, Terence L.; Tiedje, James M.; Hazen, Terry C.; Zhou, Jizhong

    2011-01-01

    A pilot-scale system was established to examine the feasibility of in situ U(VI) immobilization at a highly contaminated aquifer (U.S. DOE Integrated Field Research Challenge site, Oak Ridge, TN). Ethanol was injected intermittently as an electron donor to stimulate microbial U(VI) reduction, and U(VI) concentrations fell to below the Environmental Protection Agency drinking water standard (0.03 mg liter?1). Microbial communities from three monitoring wells were examined during active U(VI) reduction and maintenance phases with GeoChip, a high-density, comprehensive functional gene array. The overall microbial community structure exhibited a considerable shift over the remediation phases examined. GeoChip-based analysis revealed that Fe(III)-reducing bacterial (FeRB), nitrate-reducing bacterial (NRB), and sulfate-reducing bacterial (SRB) functional populations reached their highest levels during the active U(VI) reduction phase (days 137 to 370), in which denitrification and Fe(III) and sulfate reduction occurred sequentially. A gradual decrease in these functional populations occurred when reduction reactions stabilized, suggesting that these functional populations could play an important role in both active U(VI) reduction and maintenance of the stability of reduced U(IV). These results suggest that addition of electron donors stimulated the microbial community to create biogeochemical conditions favorable to U(VI) reduction and prevent the reduced U(IV) from reoxidation and that functional FeRB, SRB, and NRB populations within this system played key roles in this process. PMID:21498771

  12. Dynamics of microbial community composition and function during in-situ bioremediation of a uranium-contaminated aquifer

    SciTech Connect

    Nostrand, J.D. Van; Wu, L.; Wu, W.M.; Huang, A.; Gentry, T.J.; Deng, Y.; Carley, J.; Carrol, S.; He, Z.; Gu, B.; Luo, J.; Criddle, C.S.; Watson, D.B.; Jardine, P.M.; Marsh, T.L.; Tiedje, J.M.; Hazen, T.C.; Zhou, J.

    2010-08-15

    A pilot-scale system was established to examine the feasibility of in situ U(VI) immobilization at a highly contaminated aquifer (U.S. DOE Integrated Field Research Challenge site, Oak Ridge, TN). Ethanol was injected intermittently as an electron donor to stimulate microbial U(VI) reduction, and U(VI) concentrations fell to below the Environmental Protection Agency drinking water standard (0.03 mg liter{sup -1}). Microbial communities from three monitoring wells were examined during active U(VI) reduction and maintenance phases with GeoChip, a high-density, comprehensive functional gene array. The overall microbial community structure exhibited a considerable shift over the remediation phases examined. GeoChip-based analysis revealed that Fe(III)-reducing bacterial (FeRB), nitrate-reducing bacterial (NRB), and sulfate-reducing bacterial (SRB) functional populations reached their highest levels during the active U(VI) reduction phase (days 137 to 370), in which denitrification and Fe(III) and sulfate reduction occurred sequentially. A gradual decrease in these functional populations occurred when reduction reactions stabilized, suggesting that these functional populations could play an important role in both active U(VI) reduction and maintenance of the stability of reduced U(IV). These results suggest that addition of electron donors stimulated the microbial community to create biogeochemical conditions favorable to U(VI) reduction and prevent the reduced U(IV) from reoxidation and that functional FeRB, SRB, and NRB populations within this system played key roles in this process.

  13. Microbial Biogeography of Public Restroom Surfaces Gilberto E. Flores1

    E-print Network

    Hammerton, James

    into three general categories: those found on surfaces associated with toilets, those on the restroom floor, and those found on surfaces routinely touched with hands. On toilet surfaces, gut-associated taxa were more design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing

  14. MICROBIAL REDUCTION OF IONIC MERCURY FOR THE REMOVAL OF MERCURY FROM CONTAMINATED ENVIRONMENTS

    EPA Science Inventory

    A mercury-contaminated freshwater pond, Reality Lake (RL), was investigated in the vicinity of Oak Ridge, Tennessee. he original source of contamination was a nuclear weapons plant where elemental mercury was used from the 1950s to 1970s to enrich lithium isotopes for the product...

  15. Hydride Compressor Sorption Cooler and Surface Contamination Issues

    NASA Astrophysics Data System (ADS)

    Bowman, R. C.; Reiter, J. W.; Prina, M.; Kulleck, J. G.; Lanford, W. A.

    2003-07-01

    A continuous-duty hydrogen sorption cryocooler is being developed for the Planck spacecraft, a mission to map the cosmic microwave background beginning in 2007. This cryocooler uses six individual compressor elements (CEs) filled with the hydriding alloy LaNi4.78Sn0.22 to provide high-pressure (50 bar) hydrogen to a Joule-Thomson (J-T) expander and to absorb low-pressure (˜0.3 bar) gas from liquid hydrogen reservoirs cooled to ˜18K. Quadrupole Mass Spectrometry (QMS) showed methane in these hydride beds after cycling during initial operation of laboratory tests of the Planck engineering breadboard (EBB) cooler. These contaminants have caused problems involving plugged J-T expanders. The contaminants probably come from reactions with residual hydrocarbon species on surfaces inside the hydride bed. The hydride bed in each CE is contained in an annular volume called a "gas-gap heat switch," which serves as a reversible, intermittent thermal path to the spacecraft radiator. The gas-gap is either "off" (i.e., its pressure <1.3 Pa), or "on" (i.e., hydrogen gas at ˜4 kPa). The hydrogen pressure is varied with an independent hydride actuator containing ZrNiHx. Early EBB cooler tests showed increasing parasitic heat losses from the inner beds, suggesting residual pressures in the gas gap during its "off" state. The pressure was shown to be due to hydrogen from outgassing from metallic surfaces in the gas gap and hydrogen permeation through the inner sorbent bed wall. This gas accumulation has serious end-of-life implications, as the ZrNi actuator has limited storage capacity and any excess hydrogen would necessarily affect its operation. This paper summarizes experiments on the behavior of hydrogen in the gas gap switch and formation of methane in the CE sorbent beds.

  16. EFFECT OF IMPACT STRESS ON MICROBIAL RECOVERY ON AN AGAR SURFACE

    EPA Science Inventory

    Microbial stress due to the impaction of microorganisms onto an agar collection surface was studied experimentally. he relative recovery rates of aerosolized Pseudomonas fluorescens and Micrococcus luteus were determined as a function of the impaction velocity by using a moving a...

  17. MICROBIAL DIVERSITY IN SURFACE SEDIMENTS: A COMPARISON OF TWO ESTUARINE CONTINUUMS

    EPA Science Inventory

    The microbial diversity in estuarine sediments of the Altamaha and Savannah Rivers in Georgia were compared temporally and spatially using phospholipid fatty acid (PLFA) analysis. Surface sediment samples collected along a salinity gradient were also analyzed for ATP, TOC, and C ...

  18. Microbial community dynamics during acetate biostimulation of RDX-contaminated groundwater.

    PubMed

    Livermore, Joshua A; Jin, Yang Oh; Arnseth, Richard W; Lepuil, Michael; Mattes, Timothy E

    2013-07-16

    Biostimulation of groundwater microbial communities (e.g., with carbon sources) is a common approach to achieving in situ bioremediation of organic pollutants (e.g., explosives). We monitored a field-scale approach to remediate the explosive RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) in an aquifer near the Iowa Army Ammunition Plant in Middletown, IA. The purpose of the study was to gain insight into the effect of biostimulation on the microbial community. Biostimulation with acetate led to the onset of RDX reduction at the site, which was most apparent in monitoring well MW309. Based on previous laboratory experiments, we hypothesized that RDX degradation and metabolite production would correspond to enrichment of one or more Fe(III)-reducing bacterial species. Community DNA from MW309 was analyzed with 454 pyrosequencing and terminal restriction fragment length polymorphism. Production of RDX metabolites corresponded to a microbial community shift from primarily Fe(III)-reducing Betaproteobacteria to a community dominated by Fe(III)-reducing Deltaproteobacteria (Geobacteraceae in particular) and Bacteroidetes taxa. This data provides a firsthand field-scale microbial ecology context to in situ RDX bioremediation using modern sequencing techniques that will inform future biostimulation applications. PMID:23781876

  19. Metagenomic insights into evolution of a heavy metal-contaminated groundwater microbial community

    Microsoft Academic Search

    Christopher L. Hemme; Ye Deng; Terry J. Gentry; Matthew Wayne Fields; Liyou Wu; Soumitra Barua; Kerrie Barry; Susannah G Tringe; David B. Watson; Zhili He; Terry C. Hazen; James M. Tiedje; Edward M. Rubin; Jizhong Zhou; J Zhou

    2010-01-01

    Understanding adaptation of biological communities to environmental change is a central issue in ecology and evolution. Metagenomic analysis of a stressed groundwater microbial community reveals that prolonged exposure to high concentrations of heavy metals, nitric acid and organic solvents (?50 years) has resulted in a massive decrease in species and allelic diversity as well as a significant loss of metabolic

  20. Metal impacts on microbial biomass in the anoxic sediments of a contaminated lake

    E-print Network

    Gough, Heidi L.

    2011-01-01

    arsenic, cadmium, chromium, copper, iron, lead, manganese, and zinc) in the sedimentsarsenic and zinc concentrations, while total and sequentially extracted metal concentrations were poor predictors. Methods Metals and sedimentand sediment microbial biomass Figure 7. Comparison of pore water zinc concentrations verses pore water arsenic

  1. Subsurface characterization of groundwater contaminated by landfill leachate using microbial community profile

    E-print Network

    Vermont, University of

    leachate. We modified a self-organizing map (SOM) to weight the input variables by their relative is based on clustering a set of molecular genetic-based microbial community profiles. Microbes were sampled principal component analysis, (2) clustering the resulting principal component (PC) scores using a modified

  2. Microbial Specificity of Metallic Surfaces Exposed to Ambient Seawater

    PubMed Central

    Zaidi, B. R.; Bard, R. F.; Tosteson, T. R.

    1984-01-01

    High-molecular-weight materials associated with the extracellular matrix and film found on titanium and aluminum surfaces after exposure to flowing coastal seawater were isolated. This material was purified by hydroxylapatite chromatography and subsequently employed to produce antibodies in the toad, Bufo marinus. The antibodies were immobilized on a solid support and employed to isolate adhesion-enhancing, high-molecular-weight materials from the laboratory culture media of bacterial strains recovered from the respective metallic surfaces during the course of their exposure to seawater. The adhesion-enhancing materials produced by the surface-associated bacterial strains were immunologically related to the extracellular biofouling matrix material found on the surfaces from which these bacteria were isolated. The surface selectivity of these bacterial strains appeared to be based on the specificity of the interaction between adhesion-enhancing macromolecules produced by these bacteria and the surfaces in question. PMID:16346622

  3. A comparison of DNA profiling techniques for monitoring nutrient impact on microbial community composition during bioremediation of petroleum-contaminated soils

    Microsoft Academic Search

    DeEtta K Mills; Kristin Fitzgerald; Carol D Litchfield; Patrick M Gillevet

    2003-01-01

    Amplicon length heterogeneity PCR (LH-PCR) and terminal restriction fragment length polymorphisms (TRFLP) were used to monitor the impact that nutrient amendments had on microbial community dynamics and structural diversity during bioremediation of petroleum-contaminated soils. Slurried soils contaminated with petroleum hydrocarbons were treated in airlift bench-scale bioreactors and were either amended with optimal inorganic nutrients or left unamended. Direct DNA extraction

  4. Microbial characterization before, during and after nitrate-enhanced bioremediation of a jet fuel-contaminated aquifer

    SciTech Connect

    Thomas, J.M.; Bruce, C.L.; Gordy, V.R.; Duston, K.L.; Ward, C.H. [Rice Univ., Houston, TX (United States); Sinclair, J.L.; Hutchins, S.R.

    1995-12-31

    A JP-4 fuel-contaminated aquifer that underwent a pilot demonstration of nitrate-enhanced bioremediation was characterized microbially before, during and after treatment. The most probable number of total denitrifiers, denitrifiers that use JP-4 or JP-4 degradation products, aerobic and anaerobic protozoa, and the number of heterotrophs and JP-4 degrading microorganisms were determined. The pilot demonstration was conducted by constructing two 100 ft by 100 ft treatment cells, located in a zone of residual contamination, which received either unamended or nitrate-amended recharge water. Core materials were collected in March 1993, August 1994 and May 1995. The demonstration was initiated in April 1994. Preliminary analysis of the results indicates that the number of total denitrifiers in the treatment zone increased after 4 months of treatment but declined to initial levels by the end of the demonstration. However, the number of denitrifiers that use JP-4 or its degradation products, heterotrophs and JP-4 degraders declined after 4 months, and then increased by the final sampling, even in the control samples. Measurements of contaminant concentrations at the interim sampling indicated little removal; however, BTEX concentrations in the ground water at the final sampling were less than initial levels.

  5. Dynamic modeling of contaminant transport with surface runoff and sediment

    SciTech Connect

    Ashraf, M.S.

    1992-01-01

    Non-point source pollution in surface runoff due to agricultural activities presents one of the principal problems in the U.S. Solution to the problem of delivering pollutants is crucial to a non-point abatement program. Mathematical models can serve as tools to relate hydrologic conditions and soil properties to the processes of pollutant transport, and can be used to evaluate the effectiveness of best management practices in reducing non-point source pollutant load in surface waters. In this study, a dynamic model component is developed to simulate transport of non-point source pollutants, mostly agricultural chemicals, with surface runoff and sediment in agricultural watersheds. Algorithms are developed to route chemicals and infiltrating water through different soil increments assuming complete mixing until time of ponding or initiation of runoff. Once runoff starts, the runoff interacts with a mixing soil layer in a non-uniform fashion and exchange of chemicals takes place between runoff and the mixing soil layer. When runoff storage builds up, it is assumed that a relatively stagnant depth of runoff interacts with the mixing soil layer. This stagnant depth is obtained by applying boundary layer theory. Mass balance equations are used to route chemicals associated with runoff and sediment along the slope lengths for overland and channel flow. Model algorithms are coupled with the hydrologic and sediment transport model RUNOFF to simulate transport of contaminants with surface runoff and sediments in agricultural watersheds. The model performance is evaluated with data ranging from controlled laboratory experiments to watershed scale. The concept of non-uniform mixing is tested with a laboratory data set found in the literature. A total of fifteen runs are made, five for each of the chemicals, nitrate, phosphate, and cyanazine. The model results show good agreements with the observed yields of runoff, sediment, orthophosphate, and ammonium.

  6. High Resolution CryoFESEM of Microbial Surfaces

    NASA Astrophysics Data System (ADS)

    Erlandsen, Stanley; Lei, Ming; Martin-Lacave, Ines; Dunny, Gary; Wells, Carol

    2003-08-01

    The outer surfaces of three microorganisms, Giardia lamblia, Enterococcus faecalis, and Proteus mirabilis, were investigated by cryo-immobilization followed by sublimation of extracellular ice and cryocoating with either Pt alone or Pt plus carbon. Cryocoated samples were examined at [minus sign]125°C in either an in-lens field emission SEM or a below-the-lens field emission SEM. Cryocoating with Pt alone was sufficient for low magnification observation, but attempts to do high-resolution imaging resulted in radiolysis and cracking of the specimen surface. Double coating with Pt and carbon, in combination with high resolution backscatter electron detectors, enabled high-resolution imaging of the glycocalyx of bacteria, revealing a sponge-like network over the surface. High resolution examination of bacterial flagella also revealed a periodic substructure. Common artifacts included radiolysis leading to “cracking” of the surface, and insufficient deposition of Pt resulting in the absence of detectable surface topography.

  7. Molecular contamination study by interaction of a molecular beam with a platinum surface

    NASA Technical Reports Server (NTRS)

    Nuss, H. E.

    1976-01-01

    The capability of molecular beam scattering from a solid surface is analyzed for identification of molecular contamination of the surface. The design and setup of the molecular beam source and the measuring setup for the application of a phase sensitive measuring technique for the determination of the scattered beam intensity are described. The scattering distributions of helium and nitrogen molecular beams interacting with a platinum surface were measured for different amounts of contamination from diffusion pump oil for surface temperatures ranging from 30 to 400 C. The results indicate the scattering of molecular beams from a platinum surface is a very sensitive method for detecting surface contamination.

  8. Surface Contamination Monitor and Survey Information Management System

    SciTech Connect

    NONE

    1998-02-01

    Shonka Research Associates, Inc.`s (SRA) Surface Contamination Monitor and Survey Information management System (SCM/SIMS) is designed to perform alpha and beta radiation surveys of floors and surfaces and document the measured data. The SRA-SCM/SIMS technology can be applied to routine operational surveys, characterization surveys, and free release and site closure surveys. Any large nuclear site can make use of this technology. This report describes a demonstration of the SRA-SCM/SIMS technology. This demonstration is part of the chicago Pile-5 (CP-5) Large-Scale Demonstration Project (LSDP) sponsored by the US Department of Energy (DOE), Office of Science and Technology (ST), Deactivation and Decommissioning Focus Area (DDFA). The objective of the LSDP is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East`s (ANL) CP-5 Research Reactor Facility. The purpose of the LSDP is to demonstrate that by using innovative and improved deactivation and decommissioning (D and D) technologies from various sources, significant benefits can be achieved when compared to baseline D and D technologies.

  9. Uncertainty in assessing risks from current radioactive surface contamination standards

    SciTech Connect

    Chen, S.Y.; LePoire, D.J. (Argonne National Lab., IL (United States))

    1993-01-01

    Release standards for materials with radioactive surface contamination have been in existence in the United States for about two decades. Such standards include those issued by the American National Standards Institute, (ANSI), the U.S. Nuclear Regulatory Commission and the U.S. Department of Energy (DOE). The standards were based on the measured surface concentrations; in other words, they were [open quotes]instrumentation based.[close quotes] However, significant advancement has taken place in the area of radiation protection in the past two decades, The more stringent regulatory environment has resulted in lower dose limits; newer and more sophisticated dosimetric models have also been made available for more accurate estimates of human exposures and health risks. Moreover, the trend of standard setting has moved toward the [open quotes]risk-based[close quotes] approach away from the traditional [open quotes]instrumentation-based[close quotes] approach. It is thus necessary to reevaluate the current standards with the risk-based approach. Results of such evaluation would enable the future standard-setting activities.

  10. Remediation of uranium contaminated soils with bicarbonate extraction and microbial U(VI) reduction

    Microsoft Academic Search

    Elizabeth J. P. Phillips; Edward R. Landa; Derek R. Lovley

    1995-01-01

    Summary A process for concentrating uranium from contaminated soils in which the uranium is first extracted with bicarbonate and then the extracted uranium is precipitated with U(VI)-reducing microorganisms was evaluated for a variety of uranuum-contaminated soils. Bicarbonate (100 mM) extracted 20–94% of the uranium that was extracted with nitric acid. The U(VI)-reducing microorganism,Desulfovibrio desulfuricans reduced the U(VI) to U(IV) in

  11. Microbial evaluation of silver coated\\/impregnated sand for purification of contaminated water

    Microsoft Academic Search

    S. Naeem Mahmood; Sitwat Naeem; Najma Basit; Tanzil Haider Usmani

    1993-01-01

    Silver coated sand has been used for the disinfection of contaminated water. Highly contaminated water has been passed through 1:1, 1:2 and 1:3 mixtures of silver treated and untreated sands of 10, 35 and 60 mesh sizes and bactericidal efficiency of each mixture has been evaluated. Data in this study suggest that the sand mixtures of 35 mesh remove coliform

  12. Petroleum-Degrading Microbial Numbers in Rhizosphere and Non-Rhizosphere Crude Oil-Contaminated Soil

    Microsoft Academic Search

    W. D. Kirkpatrick; P. M. White Jr; D. C. Wolf; G. J. Thoma; C. M. Reynolds

    2008-01-01

    Phytoremediation can be a cost-effective and environmentally acceptable method to clean up crude oil-contaminated soils in situ. Our research objective was to determine the effects of nitrogen (N) additions and plant growth on the number of total hydrocarbon (TH)-, alkane-, and polycyclic aromatic hydrocarbon (PAH)-degrading microorganisms in weathered crude oil-contaminated soil. A warm-season grass, sudangrass (Sorghum sudanense (Piper) Stapf), was

  13. Microbial Characterization of Nitrification in a Shallow, Nitrogen-Contaminated Aquifer, Cape Cod, Massachusetts and Detection of a Novel Cluster Associated with Nitrifying Betaproteobacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    : Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a sewage-contaminated groundwater plume were examined for microbial and molecular evidence of nitrification processes. The first, located beneath a sewage effl...

  14. Cement-Implant Interface Contamination: Possible Reason of Inferior Clinical Outcomes for Rough Surface Cemented Stems

    PubMed Central

    Wang, Tian; Pelletier, Matthew H; Bertollo, Nicky; Crosky, Alan; Walsh, William R

    2013-01-01

    Background: Shape-closed cemented implants rely on a stronger bond and have displayed inferior clinical outcomes when compared to force-closed designs. Implant contamination such as saline, bone marrow and blood prior to cement application has the potential to affect the cement-implant bond. The consequences of implant contamination were investigated in this study. Methods: Fifty Titanium alloy (Ti-6Al-4V) dowels were separated into ten groups based on surface roughness and contaminant, and then cemented in polyvinyl chloride tubes. Push-out testing was performed at 1mm per minute. The roughness of the dowel surface was measured before and after the testing. The dowel surface and cement mantel were analyzed using a Scanning Electron Microscopy (SEM) to determine the distribution and characteristics of any debris and contaminants on the surface. Results: Contaminants largely decreased stem-cement interfacial shear strength, especially for rough surfaces. Saline produced the greatest decrease, followed by blood. The effect of bone marrow was less pronounced and similar to that of oil. Increasing surface roughness increased the interfacial bonding strength, even with contaminants. There was a non-significant increase in mean bonding strength for smooth surfaces with bone marrow and oil contamination. SEM showed that contaminants influence the interfacial bond by different mechanisms. More debris was found on rough samples following testing. Conclusions: The results of this study underscore the importance of keeping an implant free from contamination, and suggest if contamination does occur, a saline rinse may further decrease the stability of an implant. The deleterious effects of contamination on rough surface cement bonding were considerable, and indicate that contamination at the time of surgery may, in part, contribute to inferior clinical outcomes for rough surfaced cemented stems. PMID:23898352

  15. Adsorption of a biosurfactant on surfaces to enhance the disinfection of surfaces contaminated with Listeria monocytogenes.

    PubMed

    Meylheuc, T; Renault, M; Bellon-Fontaine, M N

    2006-05-25

    The effects of sodium hypochlorite (NaOCl) and peracetic acid/hydrogen peroxide (PAH) on the inactivation of adherent Listeria monocytogenes LO28 cells were examined. The surfaces tested were stainless steel and polytetrafluoroethylene (PTFE) conditioned or not with an anionic biosurfactant produced by Pseudomonas fluorescens. Dilution-neutralization methods were used to assess the effectiveness of sanitizer solutions on planktonic and adherent cells. Tests were performed on L. monocytogenes cultivated at 37 degrees Celsius (body temperature) or 20 degrees Celsius (ambient temperature). The results demonstrated that i) a total deficiency in nutrients induced by the incubation of cells in 0.15 M NaCl favored the action of NaOCl and PAH on planktonic cells; ii) by reducing the number of cells adhering to stainless steel, pre-conditioning of the surface with the biosurfactant reduced the level of contamination of the surface and thus favored the bactericidal activities of the disinfectants; and iii) the weak binding energies involved in the adsorption of the biosurfactant on PTFE surfaces resulted in there being no reduction by the polymer of the surface contamination. Furthermore, this study confirmed that adherent cells exhibited increased resistance to the actions of the disinfectants when compared to the resistance of planktonic cells. PMID:16488496

  16. Effects of Heavy Metal Contamination upon Soil Microbes: Lead-induced Changes in General and Denitrifying Microbial Communities as Evidenced by Molecular Markers

    PubMed Central

    Sobolev, Dmitri; Begonia, Maria F. T.

    2008-01-01

    Lead (Pb) is a common environmental contaminant found in soils. Unlike other metals, Pb has no biological role, and is potentially toxic to microorganisms. Effects of low (1 ppm) and high (500–2000) levels of lead (Pb) upon the soil microbial community was investigated by the PCR/DGGE analysis of the 16S and nirK gene markers, indicative of general microbial community and denitrifying community, respectively. Community analysis by use of those markers had shown that Pb has detectable effects upon the community diversity even at the lowest concentration tested. Analysis of sample diversity and similarity between the samples suggested that there are several thresholds crossed as metal concentration increase, each causing a substantial change in microbial diversity. Preliminary data obtained in this study suggest that the denitrifying microbial community adapts to elevated levels of Pb by selecting for metal-resistant forms of nitrite reductases. PMID:19151442

  17. An investigation of microbial adhesion to natural and synthetic polysaccharide-based films and its relationship with the surface energy components.

    PubMed

    Prokopovich, Polina; Perni, Stefano

    2009-01-01

    In recent years, polysaccharide-based films have been developed for many applications. Some of these are in the pharmaceutical industry, where the adhesion of microorganisms to surfaces is a concern. After adhesion of a microorganism to a solid surface has taken place, the subsequent biofilm formed can act as a vehicle for spreading infections. The aim of this study is to compare the bacterial adhesion of E. coli and S. aureus from a contaminated solid model (Tryptone Soya Agar) to a range of polysaccharide-based films. These polysaccharide-based films consist of different natural starches (potato, cassava, wheat, pea and rice) and synthetic polymers hydroxyl-propyl cellulose (HPC) and carboxyl methyl cellulose (CMC)). The surface energy parameters of the films were calculated from the contact angle measurements by the sessile drop method. Apolar and polar liquids (water, formamide and hexadecane) and the Lifshitz-Van der Waals/acid-base (LW/AB) approach were used according to the method of Van Oss, Chaundhury and Good. The surface properties of the films were also correlated to the microbial adhesion. This indicated that, for both E. coli and S. aureus, the surface roughness did not affect the microbial adhesion. Only gamma(sAB) had any correlation with the microbial adhesion and gamma(sLW) was almost constant for all the various polysaccharide films tested. In addition, the electron-donor properties of the materials, exhibited via gamma(s+), were positively correlated with the adhesion of S. aureus but not with E. coli. This was in agreement with the results of the MATS (Microbial Adhesion To Solvents) test performed on the two bacteria. This revealed that only S. aureus presented an electron-acceptor characteristic. PMID:18712504

  18. Passive standoff detection of liquid surface contaminants: recent results with CATSI

    Microsoft Academic Search

    Jean-Marc Theriault; Jim Hancock; James O. Jensen; Eldon Puckrin; Francis M. D'Amico; Carmela Jackson-Lepage

    2004-01-01

    Laboratory and field measurements for the passive standoff detection of liquid contaminants deposited on surfaces are presented. The measurements were performed at the SURFCON trials held at DRDC Suffield in September 2002. The goal of this trial was to verify that passive LWIR spectrometric sensors have the potential for remotely detecting surface contaminants. Laboratory and field data obtained with the

  19. Bacterial re-contamination of surfaces of food processing lines during cleaning in place procedures

    Microsoft Academic Search

    Caroline Le Gentil; Yahaya Sylla; Christine Faille

    2010-01-01

    The possible contamination of surfaces of food processing lines during cleaning in place (CIP) procedures was investigated. Experiments were focused on surface contamination of straight pipes and a two-way valve, chosen as an example of complex pieces of equipment. Pipes and a two-way valve were inserted into a CIP rig, at the same time as a series of pipes highly

  20. EFFECTS OF POLLUTANTS ON MICROBIAL ACTIVITIES IN ESTUARINE SURFACE FILMS

    EPA Science Inventory

    Samples of inshore surface films from Escambia Bay, Florida and from sites in the North Sea yielded populations of aerobic, heterotrophic microorganisms up to 10 to the 8th power per ml or 1,000,000 per sq. cm. Hydrocarbonoclastic organisms were in relatively low populations. A c...

  1. Critical contaminant\\/critical pathway analysis - surface water transport for nonradioactive contaminants

    Microsoft Academic Search

    Kuo-Fu

    1996-01-01

    The health risks for an individual exposed to contaminants released from SRS outfalls from 1989 to 1995 were estimated. The exposure pathways studied are ingestion of drinking water, ingestion of contaminated fish and dermal contact with contaminants in water while swimming. The estimated incremental risks for an individual developing cancer vary from 3.E-06 to 1.0E-05. The estimated total exposure chronic

  2. Recovery of bacillus spore contaminants from rough surfaces: a challenge to space mission cleanliness control.

    PubMed

    Probst, Alexander; Facius, Rainer; Wirth, Reinhard; Wolf, Marco; Moissl-Eichinger, Christine

    2011-03-01

    Microbial contaminants on spacecraft can threaten the scientific integrity of space missions due to probable interference with life detection experiments. Therefore, space agencies measure the cultivable spore load ("bioburden") of a spacecraft. A recent study has reported an insufficient recovery of Bacillus atrophaeus spores from Vectran fabric, a typical spacecraft airbag material (A. Probst, R. Facius, R. Wirth, and C. Moissl-Eichinger, Appl. Environ. Microbiol. 76:5148-5158, 2010). Here, 10 different sampling methods were compared for B. atrophaeus spore recovery from this rough textile, revealing significantly different efficiencies (0.5 to 15.4%). The most efficient method, based on the wipe-rinse technique (foam-spatula protocol; 13.2% efficiency), was then compared to the current European Space Agency (ESA) standard wipe assay in sampling four different kinds of spacecraft-related surfaces. Results indicate that the novel protocol out-performed the standard method with an average efficiency of 41.1% compared to 13.9% for the standard method. Additional experiments were performed by sampling Vectran fabric seeded with seven different spore concentrations and five different Bacillus species (B. atrophaeus, B. anthracis Sterne, B. megaterium, B. thuringiensis, and B. safensis). Among these, B. atrophaeus spores were recovered with the highest (13.2%) efficiency and B. anthracis Sterne spores were recovered with the lowest (0.3%) efficiency. Different inoculation methods of seeding spores on test surfaces (spotting and aerosolization) resulted in different spore recovery efficiencies. The results of this study provide a step forward in understanding the spore distribution on and recovery from rough surfaces. The results presented will contribute relevant knowledge to the fields of astrobiology and B. anthracis research. PMID:21216908

  3. Recovery of Bacillus Spore Contaminants from Rough Surfaces: a Challenge to Space Mission Cleanliness Control?

    PubMed Central

    Probst, Alexander; Facius, Rainer; Wirth, Reinhard; Wolf, Marco; Moissl-Eichinger, Christine

    2011-01-01

    Microbial contaminants on spacecraft can threaten the scientific integrity of space missions due to probable interference with life detection experiments. Therefore, space agencies measure the cultivable spore load (“bioburden”) of a spacecraft. A recent study has reported an insufficient recovery of Bacillus atrophaeus spores from Vectran fabric, a typical spacecraft airbag material (A. Probst, R. Facius, R. Wirth, and C. Moissl-Eichinger, Appl. Environ. Microbiol. 76:5148-5158, 2010). Here, 10 different sampling methods were compared for B. atrophaeus spore recovery from this rough textile, revealing significantly different efficiencies (0.5 to 15.4%). The most efficient method, based on the wipe-rinse technique (foam-spatula protocol; 13.2% efficiency), was then compared to the current European Space Agency (ESA) standard wipe assay in sampling four different kinds of spacecraft-related surfaces. Results indicate that the novel protocol out-performed the standard method with an average efficiency of 41.1% compared to 13.9% for the standard method. Additional experiments were performed by sampling Vectran fabric seeded with seven different spore concentrations and five different Bacillus species (B. atrophaeus, B. anthracis Sterne, B. megaterium, B. thuringiensis, and B. safensis). Among these, B. atrophaeus spores were recovered with the highest (13.2%) efficiency and B. anthracis Sterne spores were recovered with the lowest (0.3%) efficiency. Different inoculation methods of seeding spores on test surfaces (spotting and aerosolization) resulted in different spore recovery efficiencies. The results of this study provide a step forward in understanding the spore distribution on and recovery from rough surfaces. The results presented will contribute relevant knowledge to the fields of astrobiology and B. anthracis research. PMID:21216908

  4. Trimming and washing poultry carcass to reduce microbial contamination: A comparative study.

    PubMed

    Stefani, Lenita Moura; Backes, Rodrigo Guilherme; Faria, Glaucia Amorim; Biffi, Claudia Pies; de Almeida, Juliana Maria; da Silva, Helen Krystine; das Neves, Gabriella Bassi; Langaro, Anaiara

    2014-12-01

    The objective of this study was to compare the efficiency of washing and trimming broiler carcasses to reduce bacterial contamination. At the postevisceration site, 100 broiler carcasses were collected during 4 visits to a slaughterhouse in Santa Catarina State, Brazil. Birds were from the same flock, age, and approximately 2.4 kg of weight. Groups were as follows: group 1, with fecal contamination; group 2, without fecal contamination; group 3, with fecal contamination and trimmed; group 4, with fecal contamination and washed; group 5, with fecal contamination, and washed and trimmed. Carcass washings were performed with at least 1.5 L/bird of potable water (0.5 to 1 mg/kg of residual chlorine) at room temperature (20-25°C) using spray cabinets with 44 spray nozzles distributed into 2 chambers (pressure of 2 kgf/cm(2) and 4 kgf/cm(2)). Washed carcasses (trimmed or not) showed significantly (P < 0.05) lower counts of aerobic mesophiles (plate count agar) on the third evaluation, and even lower (P < 0.01) counts for total coliforms (CT) and fecal coliforms (Escherichia coli). Trimmed carcasses showed significantly lower counts (P < 0.05) for plate count agar; however, we observed higher counts for E. coli (P < 0.05). The association of both treatments (washing and trimming) showed significantly higher (P < 0.05) counts for coliforms (CT and E. coli). We can conclude that the washing method is overall more efficient than the trimming method to decontaminate chicken carcasses at the postevisceration site. Hopefully, our findings can help poultry companies to minimize production costs by applying the washing method for carcass decontamination. PMID:25306453

  5. [Correlation of bacteria in the contaminated drug and the environmental microbes in the clean room for pharmaceutical microbial test investigated by FTIR].

    PubMed

    Pei, Lin; Hu, Chang-qin; Ma, Shi-hong; Dai, Hui; Hang, Tai-jun

    2007-11-01

    The FTIR method was used to investigate the correlation of bacteria in the contaminated drug and the environmental microbes in the clean room for pharmaceutical microbial test. The similarity of bacteria in the contaminated drug and environmental microbes was compared by critical hit value method and cluster analysis method. This constructed the FTIR spectra library of clean room environmental microbe, and determined the criterion to promptly judge if the bacteria isolated from pharmaceuticals were contaminated by environment or not, hence the exactness of "one-off report" of sterile test result can be guaranteed, and can be used for the dynamic monitoring of environmental bacteria of clean room. The method is proven to be simple, accurate and rapid, and can be easily spread to the pharmaceutical microbial control. PMID:18300477

  6. PCB detection by immunoassay -- A wipe test for surface contamination

    SciTech Connect

    Dautlick, J.X.; Teaney, G.B.; Hudak, R.T.; Melby, J.M. [Strategic Diagnostics Industries Inc., Newark, DE (United States)

    1995-12-31

    Immunoassay based field screening methods are gaining acceptance by the environmental diagnostics industry for on-site characterization and remediation monitoring. Polychlorinated biphenyls (PCBs), a family of molecules classified as potential carcinogens, can be easily detected on-site by immunoassay screening methods. This results in reduced project cost and improved onsite efficiency, since field screening immunoassays short cut the long turn around time of laboratory analysis while providing reliable results. On site wipe test technology for assessing PCB contamination on surfaces such as walls and floors of PCB storage facilities has been developed to supplement the D TECH{trademark} PCB soil assay. This sampling technique can also be used to monitor for transformer leaks, spills and to evaluate equipment decontamination processes. The D TECH PCB wipe test is quick, cost effective, highly specific and user friendly. The surface is sampled by wiping a 100 cm{sup 2} area with a 1 cm{sup 2} pad saturated with an extractant. The PCB is extracted from the sampling pad during a short extraction step. The sample is filtered, diluted, and run in the D TECH PCB field screening system. The components of the immunoassay include PCB specific antibodies (Ab) covalently linked to small latex particles, a PCB analog which is covalently linked to alkaline phosphatase, and the free PCB from the sample. The free PCB competes with the enzyme linked analog for the Ab binding sites. The latex particles are then collected on a filter device, washed, and an enzyme substrate is added. The amount of color produced is inversely proportional to the concentration of free PCB on the sample, and can be determined using a hand held reflectometer, or a color card.

  7. Microbial Community Dynamics during the Bioremediation Process of Chlorimuron-Ethyl-Contaminated Soil by Hansschlegelia sp. Strain CHL1

    PubMed Central

    Yang, Liqiang; Li, Xinyu; Li, Xu; Su, Zhencheng; Zhang, Chenggang; Zhang, Huiwen

    2015-01-01

    Long-term and excessive application of chlorimuron-ethyl has led to a series of environmental problems. Strain Hansschlegelia sp. CHL1, a highly efficient chlorimuron-ethyl degrading bacterium isolated in our previous study, was employed in the current soil bioremediation study. The residues of chlorimuron-ethyl in soils were detected, and the changes of soil microbial communities were investigated by phospholipid fatty acid (PLFA) analysis. The results showed that strain CHL1 exhibited significant chlorimuron-ethyl degradation ability at wide range of concentrations between 10?g kg-1 and 1000?g kg-1. High concentrations of chlorimuron-ethyl significantly decreased the total concentration of PLFAs and the Shannon-Wiener indices and increased the stress level of microbes in soils. The inoculation with strain CHL1, however, reduced the inhibition on soil microbes caused by chlorimuron-ethyl. The results demonstrated that strain CHL1 is effective in the remediation of chlorimuron-ethyl-contaminated soil, and has the potential to remediate chlorimuron-ethyl contaminated soils in situ. PMID:25689050

  8. Microbial Community Dynamics during the Bioremediation Process of Chlorimuron-Ethyl-Contaminated Soil by Hansschlegelia sp. Strain CHL1.

    PubMed

    Yang, Liqiang; Li, Xinyu; Li, Xu; Su, Zhencheng; Zhang, Chenggang; Zhang, Huiwen

    2015-01-01

    Long-term and excessive application of chlorimuron-ethyl has led to a series of environmental problems. Strain Hansschlegelia sp. CHL1, a highly efficient chlorimuron-ethyl degrading bacterium isolated in our previous study, was employed in the current soil bioremediation study. The residues of chlorimuron-ethyl in soils were detected, and the changes of soil microbial communities were investigated by phospholipid fatty acid (PLFA) analysis. The results showed that strain CHL1 exhibited significant chlorimuron-ethyl degradation ability at wide range of concentrations between 10?g kg-1 and 1000?g kg-1. High concentrations of chlorimuron-ethyl significantly decreased the total concentration of PLFAs and the Shannon-Wiener indices and increased the stress level of microbes in soils. The inoculation with strain CHL1, however, reduced the inhibition on soil microbes caused by chlorimuron-ethyl. The results demonstrated that strain CHL1 is effective in the remediation of chlorimuron-ethyl-contaminated soil, and has the potential to remediate chlorimuron-ethyl contaminated soils in situ. PMID:25689050

  9. Evidence of methylmercury production and modification of the microbial community structure in estuary sediments contaminated with wastewater treatment plant effluents.

    PubMed

    Ramond, Jean-Baptiste; Petit, Fabienne; Quillet, Laurent; Ouddane, Baghdad; Berthe, Thierry

    2011-05-01

    The Seine's estuary (France) waters are the receptacle of effluents originating from wastewater treatment plants (WWTP). In this estuary, mudflats are deposition zones for sediments and their associated contaminants, and play an essential role in the mercury (Hg) biogeochemical cycle mainly due to indigenous microorganisms. Microcosms were used to assess the impact of WWTP-effluents on mercury methylation by monitoring Hg species (total dissolved Hg in porewater, methylmercury and total mercury) and on microbial communities in sediments. After effluent amendment, methylmercury (MeHg) concentrations increased in relation with the total Hg and organic matter content of the WWTP-effluents. A correlation was observed between MeHg and acid-volatile-sulfides concentrations. Quantification of sulfate-reducing microorganisms involved in Hg methylation showed no increase of their abundance but their activity was probably enhanced by the organic matter supplied with the effluents. WWTP-effluent spiking modified the bacterial community fingerprint, mainly influenced by Hg contamination and the organic matter amendment. PMID:21429530

  10. Mineralogical and Microbial Controls on Iron Reduction in a Contaminated Aquifer-Wetland System

    E-print Network

    Howson, Andrea Melissa

    2011-02-22

    minerals are important controls on iron reduction in natural systems. For the first phase of this research a series of sequential chemical extractions was performed on a core taken from a landfill-leachate-contaminated wetland-aquifer system at the Norman...

  11. NATURAL ARSENIC CONTAMINATION OF HOLOCENE ALLUVIAL AQUIFERS BY LINKED TECTONIC, WEATHERING, AND MICROBIAL PROCESSES

    EPA Science Inventory

    Linked tectonic, geochemical, and biologic processes lead to natural arsenic contamination of groundwater in Holocene alluvial aquifers, which are the main threat to human health around the world. These groundwaters are commonly found a long distance from their ultimate source of...

  12. Effects of gamma irradiation on microbial contamination and extraction yields of Korean medicinal herbs

    Microsoft Academic Search

    Mi-Jung Kim; Hong-Sun Yook; Myung-Woo Byun

    2000-01-01

    Effects of gamma irradiation on hygienic quality and extraction yields in twenty-one kinds of Korean medicinal herbs were investigated. Gamma irradiation at 5–10 kGy inactivated contaminating microorganisms. The total extraction yield in fifteen kinds of the investigated medicinal herbs increased by 5–25% by a dose of 10 kGy.

  13. Effects of gamma irradiation on microbial contamination and extraction yields of Korean medicinal herbs

    Microsoft Academic Search

    M.-J. Kim; H.-S. Yook; M.-W. Byun

    2000-01-01

    Effects of gamma irradiation on hygienic quality and extraction yields in twenty-one kinds of Korean medicinal herbs were investigated. Gamma irradiation at 5-10 kGy inactivated contaminating microorganisms. The total extraction yield in fifteen kinds of the investigated medicinal herbs increased by 5-25% by a dose of 10 kGy.

  14. INFLUENCE OF EQUINE FECAL CONTAMINATION ON MICROBIAL COMMUNITY STRUCTURE IN A SUB-WATERSHED

    EPA Science Inventory

    As monitoring of watershed water quality is directly related to proposed uses, it is important for our Naton's water systems that the d4etemrination of and distinction between fecal contamination source is made. The most common water quality monitoring approach is to screen for f...

  15. MICROBIAL PROCESSES AFFECTING MONITORED NATURAL ATTENUATION OF CONTAMINANTS IN THE SUBSURFACE

    EPA Science Inventory

    Among the alternatives considered for the remediation of soil and ground water at hazardous wastes sites are the use of natural processes to reduce or remove the contaminants of concern. Under favorable conditions, the use of natural attenuation can result in significant cost sa...

  16. Passive standoff detection of liquid surface contaminants: recent results with CATSI

    NASA Astrophysics Data System (ADS)

    Theriault, Jean-Marc; Hancock, Jim; Jensen, James O.; Puckrin, Eldon; D'Amico, Francis M.; Jackson-Lepage, Carmela

    2004-02-01

    Laboratory and field measurements for the passive standoff detection of liquid contaminants deposited on surfaces are presented. The measurements were performed at the SURFCON trials held at DRDC Suffield in September 2002. The goal of this trial was to verify that passive LWIR spectrometric sensors have the potential for remotely detecting surface contaminants. Laboratory and field data obtained with the passive CATSI sensor are analyzed. For laboratory measurements, variable amounts of liquid H-contaminant were deposited on high-reflectivity and low-reflectivity surfaces of aluminum and Mylar. Field measurements were performed at a standoff distance of 60 m on aluminium plates covered with the H-contaminant and on low-reflectivity surfaces (armored personnel carrier surface and sod). Results indicate that contaminants deposited on high-reflectivity surfaces can be detected, identified and possibly quantified. The contaminants deposited on low-reflectivity surfaces can usually be detected but cannot be identified based on simple correlations with the absorption spectrum of the contaminant. The inhomogeneous layer model developed to explain the spectral radiance associated with non-uniform contaminant coverage is also presented.

  17. Microbial contamination of glaucoma eyedrops used by patients compared with ocular medications used in the hospital.

    PubMed

    Teuchner, Barbara; Wagner, Julia; Bechrakis, Nikolaos E; Orth-Höller, Dorothea; Nagl, Markus

    2015-02-01

    The aim of this study was to compare the percentage of contamination of multiuse eyedrops applied by glaucoma patients at home and by the medical personnel at the outpatient department, the ward, and the operating room of our Department of Ophthalmology.Eyedrops were collected over a period of 11 months. Samples were taken from the dropper tip (smear), drops, and the residual fluid inside the bottle and cultivated on blood agar. Colony forming units were counted and identified by mass spectrometry.The percentage of contamination was significantly higher in eyedrops applied by the patients (29/119; 24.4%, P?contaminated than antibiotic and anesthetic eyedrops (P?contaminated than the drops and the residual internal fluid. For eyedrops from the ward, the opposite was true. Pathogenic strains (Pseudomonas aeruginosa, Serratia marcescens, Acinetobacter lwoffii, Stenotrophomonas maltophilia, and Staphylococcus aureus) were found only in 6 bottles (1.5%), whereas most of the detected microbes belonged to human or environmental flora.This study underlines the importance of hygienic handling of eyedrops and raises the question of whether single-use glaucoma medication might be preferred to reduce the risk of contamination. PMID:25715262

  18. Characterization of microbial contamination in United States Air Force aviation fuel tanks.

    PubMed

    Rauch, Michelle E; Graef, Harold W; Rozenzhak, Sophie M; Jones, Sharon E; Bleckmann, Charles A; Kruger, Randell L; Naik, Rajesh R; Stone, Morley O

    2006-01-01

    Bacteria and fungi, isolated from United States Air Force (USAF) aviation fuel samples, were identified by gas chromatograph fatty acid methyl ester (GC-FAME) profiling and 16S or 18S rRNA gene sequencing. Thirty-six samples from 11 geographically separated USAF bases were collected. At each base, an above-ground storage tank, a refueling truck, and an aircraft wing tank were sampled at the lowest sample point, or sump, to investigate microbial diversity and dispersion within the fuel distribution chain. Twelve genera, including four Bacillus species and two Staphylococcus species, were isolated and identified. Bacillus licheniformis, the most prevalent organism isolated, was found at seven of the 11 bases. Of the organisms identified, Bacillus sp., Micrococcus luteus, Sphinogmonas sp., Staphylococcus sp., and the fungus Aureobasidium pullulans have previously been isolated from aviation fuel samples. The bacteria Pantoea ananatis, Arthrobacter sp., Alcaligenes sp., Kocuria rhizophilia, Leucobacter komagatae, Dietza sp., and the fungus Discophaerina fagi have not been previously reported in USAF aviation fuel. Only at two bases were the same organisms isolated from all three sample points in the fuel supply distribution chain. Isolation of previously undocumented organisms suggests either, changes in aviation fuel microbial community in response to changes in aviation fuel composition, additives and biocide use, or simply, improvements in isolation and identification techniques. PMID:16328508

  19. Winter survival of microbial contaminants in soil: An in situ verification.

    PubMed

    Bucci, Antonio; Allocca, Vincenzo; Naclerio, Gino; Capobianco, Giovanni; Divino, Fabio; Fiorillo, Francesco; Celico, Fulvio

    2015-01-01

    The aim of the research was to evaluate, at site scale, the influence of freezing and freeze/thaw cycles on the survival of faecal coliforms and faecal enterococci in soil, in a climate change perspective. Before the winter period and during grazing, viable cells of faecal coliforms and faecal enterococci were detected only in the first 10cm below ground, while, after the winter period and before the new seasonal grazing, a lower number of viable cells of both faecal indicators was detected only in some of the investigated soil profiles, and within the first 5cm. Taking into consideration the results of specific investigations, we hypothesise that the non-uniform spatial distribution of grass roots within the studied soil can play an important role in influencing this phenomenon, while several abiotic factors do not play any significant role. Taking into account the local trend in the increase of air temperature, a different distribution of microbial pollution over time is expected in spring waters, in future climate scenarios. The progressive increase in air temperature will cause a progressive decrease in freeze/thaw cycles at higher altitudes, minimising cold shocks on microbial cells, and causing spring water pollution also during winter. PMID:25597671

  20. Comparative metagenomic analysis of soil microbial communities across three hexachlorocyclohexane contamination levels.

    PubMed

    Sangwan, Naseer; Lata, Pushp; Dwivedi, Vatsala; Singh, Amit; Niharika, Neha; Kaur, Jasvinder; Anand, Shailly; Malhotra, Jaya; Jindal, Swati; Nigam, Aeshna; Lal, Devi; Dua, Ankita; Saxena, Anjali; Garg, Nidhi; Verma, Mansi; Kaur, Jaspreet; Mukherjee, Udita; Gilbert, Jack A; Dowd, Scot E; Raman, Rajagopal; Khurana, Paramjit; Khurana, Jitendra P; Lal, Rup

    2012-01-01

    This paper presents the characterization of the microbial community responsible for the in-situ bioremediation of hexachlorocyclohexane (HCH). Microbial community structure and function was analyzed using 16S rRNA amplicon and shotgun metagenomic sequencing methods for three sets of soil samples. The three samples were collected from a HCH-dumpsite (450 mg HCH/g soil) and comprised of a HCH/soil ratio of 0.45, 0.0007, and 0.00003, respectively. Certain bacterial; (Chromohalobacter, Marinimicrobium, Idiomarina, Salinosphaera, Halomonas, Sphingopyxis, Novosphingobium, Sphingomonas and Pseudomonas), archaeal; (Halobacterium, Haloarcula and Halorhabdus) and fungal (Fusarium) genera were found to be more abundant in the soil sample from the HCH-dumpsite. Consistent with the phylogenetic shift, the dumpsite also exhibited a relatively higher abundance of genes coding for chemotaxis/motility, chloroaromatic and HCH degradation (lin genes). Reassembly of a draft pangenome of Chromohalobacter salaxigenes sp. (?8X coverage) and 3 plasmids (pISP3, pISP4 and pLB1; 13X coverage) containing lin genes/clusters also provides an evidence for the horizontal transfer of HCH catabolism genes. PMID:23029440

  1. Soil microbial community toxic response to atrazine and its residues under atrazine and lead contamination.

    PubMed

    Chen, Qinglin; Yang, Baoshan; Wang, Hui; He, Fei; Gao, Yongchao; Scheel, Ryan A

    2015-01-01

    Intensive use of atrazine and extensive dispersal of lead (Pb) have occurred in farmland with chemical agriculture development. However, the toxicological effect of their presence on soil microorganism remains unknown. The objective of this study was to investigate the impacts of atrazine or Pb on the soil microbiota, soil net nitrogen mineralization, and atrazine residues over a 28-day microcosm incubation. The Shannon-Wiener diversity index, typical microbe species, and a Neighbor-joining tree of typical species from sequencing denaturing gradient gel electrophoresis (DGGE) bands were determined across periodical sampling times. The results showed that the existence of atrazine or Pb (especially high concentration) in soils reduced microbial diversity (the lowest H value is 2.23) compared to the control (H?=?2.59) after a 28-day incubation. The species richness reduced little (from 17~19 species to 16~17 species) over the research time. But soil microbial community was significantly affected by the incubation time after the exposure to atrazine or Pb. The combination of atrazine and Pb had a significant inhibition effect on soil net nitrogen nitrification. Atrazine and Pb significantly stimulated soil cumulative net nitrogen mineralization and nitrification. Pb (300 and 600 mg kg(-1)) accelerated the level of atrazine dissipation. The exposure might stimulate the significant growth of the autochthonous soil degraders which may use atrazine as C source and accelerate the dissipation of atrazine in soils. PMID:25106517

  2. Comparative Metagenomic Analysis of Soil Microbial Communities across Three Hexachlorocyclohexane Contamination Levels

    PubMed Central

    Sangwan, Naseer; Lata, Pushp; Dwivedi, Vatsala; Singh, Amit; Niharika, Neha; Kaur, Jasvinder; Anand, Shailly; Malhotra, Jaya; Jindal, Swati; Nigam, Aeshna; Lal, Devi; Dua, Ankita; Saxena, Anjali; Garg, Nidhi; Verma, Mansi; Kaur, Jaspreet; Mukherjee, Udita; Gilbert, Jack A.; Dowd, Scot E.; Raman, Rajagopal; Khurana, Paramjit; Khurana, Jitendra P.; Lal, Rup

    2012-01-01

    This paper presents the characterization of the microbial community responsible for the in-situ bioremediation of hexachlorocyclohexane (HCH). Microbial community structure and function was analyzed using 16S rRNA amplicon and shotgun metagenomic sequencing methods for three sets of soil samples. The three samples were collected from a HCH-dumpsite (450 mg HCH/g soil) and comprised of a HCH/soil ratio of 0.45, 0.0007, and 0.00003, respectively. Certain bacterial; (Chromohalobacter, Marinimicrobium, Idiomarina, Salinosphaera, Halomonas, Sphingopyxis, Novosphingobium, Sphingomonas and Pseudomonas), archaeal; (Halobacterium, Haloarcula and Halorhabdus) and fungal (Fusarium) genera were found to be more abundant in the soil sample from the HCH-dumpsite. Consistent with the phylogenetic shift, the dumpsite also exhibited a relatively higher abundance of genes coding for chemotaxis/motility, chloroaromatic and HCH degradation (lin genes). Reassembly of a draft pangenome of Chromohalobacter salaxigenes sp. (?8X coverage) and 3 plasmids (pISP3, pISP4 and pLB1; 13X coverage) containing lin genes/clusters also provides an evidence for the horizontal transfer of HCH catabolism genes. PMID:23029440

  3. Application of gamma irradiation to reduce microbial contamination in herbal cosmetic products

    NASA Astrophysics Data System (ADS)

    Neramitmansook, Naruemon; Chahorm, Kanchana; Prakhongsil, Panchalee; Phianphak, Wannipa; Keawchoung, Pravait

    2012-08-01

    This study addresses the decontamination of herbal powder cosmetics by gamma irradiation to reduce the total microbial colony count in facial herbal powder, herbal rose brush on and talcum. Pre-irradiated samples showed total colony counts of 3.00×104, 2.70×104 and 1.00×103 CFU/g. At 3rd day after application, irradiation reduced the total colony counts to 1.90×102, 6.00×102 and 1.20×102 CFU/g. Moreover, the total colony counts of the three samples were found to be less than 100 CFU/g after 3 months storage. The non-uniformity of ?E* revealed that time affected the color of brush on and talcum, which differed from their original color; however, irradiation affected the colors of the brush on only (P<0.05), by reducing its brightness and increasing redness and yellowness of the products. Paired preference tests were conducted in facial herbal powder and herbal rose brush on. The results showed no significant preferences between the non irradiated and irradiated of the two products at P max=75%, ?=0.05, ?=0.10. This concludes that the irradiation does not affect the preference of the products, and it can be an alternative technology to reduce microbial decontaminations in herbal products.

  4. Transport and Fate of Contaminants in Surface Water

    E-print Network

    Pasternack, Gregory B.

    exist for the transformation and transport of contaminants in water. Knowledge of a contaminant and inorganic solids from weathered rocks, detritus imported from the catchment basin (e.g., leaves, twigs originates from within the water body. It includes ungrazed plant components such as cells and tissues

  5. Monitoring of subsurface contaminants with borehole\\/surface resistivity measurements

    Microsoft Academic Search

    M. J. Wilt; C. F. Tsang

    1985-01-01

    Three-dimensional resistivity modeling was performed to simulate the changes in resistivity due to the leakage of fluid contaminants into an aquifer. The simulation represents a case where the fluid is introduced into a 25 m aquifer at a depth of 45 m. The contaminant fluid is assumed to be electrically more conductive than the in-situ ground water. Resistivity measurements were

  6. Soil contamination of plant surfaces from grazing and rainfall interactions

    Microsoft Academic Search

    T. G. Hinton; J. M. Stoll; L. Tobler

    1995-01-01

    Contaminants often attach to soil particles, and their subsequent environmental transport is largely determined by processes that govern soil movement. We examined the influence of grazing intensity on soil contamination of pastures. Four different grazing densities of sheep were tested against an ungrazed control plot. Scandium concentrations were determined by neutron activation analysis and was used as a tracer of

  7. Surface and borehole electromagnetic imaging of conducting contaminant plumes

    SciTech Connect

    Berryman, J. G., LLNL

    1998-07-01

    Electromagnetic induction tomography is a promising new tool for imaging electrical conductivity variations in the earth. The EM source field is produced by induction coil (magnetic dipole) transmitters deployed at the surface or in boreholes. Vertical and horizontal component magnetic field detectors are deployed in other boreholes or on the surface. Sources and receivers are typically deployed in a configuration surrounding the region of interest. The goal of this procedure is to image electrical conductivity variations in the earth, much as x-ray tomography is used to image density variations through cross-sections of the body. Although such EM field techniques have been developed and applied, the algorithms for inverting the magnetic field data to produce the desired images of electrical conductivity have not kept pace. One of the main reasons for the lag in the algorithm development has been the fact that the magnetic induction problem is inherently three dimensional; other imaging methods such as x-ray and seismic can make use of two-dimensional approximations that are not too far from reality, but we do not have this luxury in EM induction tomography. In addition, previous field experiments were conducted at controlled test sites that typically do not have much external noise or extensive surface clutter problems often associated with environmental sites. To use the same field techniques in environments more typical of cleanup sites requires a new set of data processing tools to remove the effects of both noise and clutter. The goal of this project is to join theory and experiment to produce enhanced images of electrically conducting fluids underground, allowing better localization of contaminants and improved planning strategies for the subsequent remediation efforts. After explaining the physical context in more detail, this report will summarize the progress made in the first 18 months of this project: (1) on code development and (2) on field tests of these methods. We conclude with a brief statement of the research directions for the remainder of this three year project.

  8. An efficient approach to cathode operational parameters optimization for microbial fuel cell using response surface methodology

    PubMed Central

    2014-01-01

    Background In the recent study, optimum operational conditions of cathode compartment of microbial fuel cell were determined by using Response Surface Methodology (RSM) with a central composite design to maximize power density and COD removal. Methods The interactive effects of parameters such as, pH, buffer concentration and ionic strength on power density and COD removal were evaluated in two-chamber microbial batch-mode fuel cell. Results Power density and COD removal for optimal conditions (pH of 6.75, buffer concentration of 0.177 M and ionic strength of cathode chamber of 4.69 mM) improve by 17 and 5%, respectively, in comparison with normal conditions (pH of 7, buffer concentration of 0.1 M and ionic strength of 2.5 mM). Conclusions In conclusion, results verify that response surface methodology could successfully determine cathode chamber optimum operational conditions. PMID:24423039

  9. Influence of Carbon and Microbial Community Priming on the Attenuation of Uranium in a Contaminated Floodplain Aquifer.

    PubMed

    Mouser, P J; N'Guessan, L A; Qafoku, N P; Sinha, M; Williams, K H; Dangelmayr, M; Resch, C T; Peacock, A; Wang, Z; Figueroa, L; Long, P E

    2014-07-21

    The capacity for subsurface sediments to sequester radionuclide contaminants, such as uranium (U), and retain them after bioremediation efforts are completed is critical to the long-term stewardship of re-mediated sites. In U bioremediation strategies, carbon amendment stimulates bioreduction of U(VI) to U(IV), immobilizing it within the sediments. Sediments enriched in natural organic matter are naturally capable of sequestering significant U, but may serve as sources to the aquifer, contributing to plume persistence. Two types of organic-rich sediments were compared to better understand U release mechanisms. Sediments that were artificially primed for U removal were retrieved from an area previously biostimulated while detrital-rich sediments were collected from a location never subject to amendment. Batch incubations demonstrated that primed sediments rapidly removed uranium from the groundwater, whereas naturally reduced sediments released a sizeable portion of U before U(VI)-reduction commenced. Column experiments confirmed that U release persisted for 65 pore volumes in naturally reduced sediments, demonstrating their sink-source behavior. Acetate addition to primed sediments shifted the microbial community from sulfate-reducing bacteria within Desulfobacteraceae to the iron-reducing Geobacteraceae and Firmicutes, associated with efficient U(VI) removal and retention, respectively. In contrast, Geobacteraceae communities in naturally reduced sediments were replaced by sequences with similarity to Pseudomonas spp. during U release, while U(VI) removal only occurred with enrichment of Firmicutes. These investigations stress the importance of characterizing zones with heterogeneous carbon pools at U-contaminated sites prior to the determination of a remedial strategy to identify areas, which may contribute to long-term sourcing of the contaminants. PMID:25047748

  10. A comparison of DNA profiling techniques for monitoring nutrient impact on microbial community composition during bioremediation of petroleum-contaminated soils.

    PubMed

    Mills, DeEtta K; Fitzgerald, Kristin; Litchfield, Carol D; Gillevet, Patrick M

    2003-07-01

    Amplicon length heterogeneity PCR (LH-PCR) and terminal restriction fragment length polymorphisms (TRFLP) were used to monitor the impact that nutrient amendments had on microbial community dynamics and structural diversity during bioremediation of petroleum-contaminated soils. Slurried soils contaminated with petroleum hydrocarbons were treated in airlift bench-scale bioreactors and were either amended with optimal inorganic nutrients or left unamended. Direct DNA extraction and PCR amplification of whole eubacterial community DNA were performed with universal primers that bracketed the first two or three hypervariable regions of the 16S rDNA gene sequences. The LH-PCR method profiled a more diverse microbial community than did the TRFLP method. The LH-PCR method also tracked differences between the communities due to nutrient amendments. An in silico database search for bacterial genera with amplicon lengths represented in the community fingerprints was performed. It was possible to qualitatively identify different groups in the microbial community based on the amplicon length variations. A similar "virtual" search was performed for the TRFLP fragments using the web-based TAP-TRFLP program. Cloning and sequencing of the PCR products confirmed the in silico database matches. The application of the LH-PCR method as a monitoring tool for bioremediation could greatly enhance and extend the current understanding of the microbial community dynamics during the biodegradation of environmental contaminants. PMID:12732422

  11. Formation of recent Pb-Ag-Au mineralization by potential sub-surface microbial activity

    NASA Astrophysics Data System (ADS)

    Tornos, Fernando; Velasco, Francisco; Menor-Salván, César; Delgado, Antonio; Slack, John F.; Escobar, Juan Manuel

    2014-08-01

    Las Cruces is a base-metal deposit in the Iberian Pyrite Belt, one of the world’s best-known ore provinces. Here we report the occurrence of major Pb-Ag-Au mineralization resulting from recent sub-surface replacement of supergene oxyhydroxides by carbonate and sulphide minerals. This is probably the largest documented occurrence of recent microbial activity producing an ore assemblage previously unknown in supergene mineralizing environments. The presence of microbial features in the sulphides suggests that these may be the first-described natural bacteriomorphs of galena. The low ?13C values of the carbonate minerals indicate formation by deep anaerobic microbial processes. Sulphur isotope values of sulphides are interpreted here as reflecting microbial reduction in a system impoverished in sulphate. We suggest that biogenic activity has produced around 3.1 × 109?moles of reduced sulphur and 1010?moles of CO2, promoting the formation of ca. 1.19?Mt of carbonates, 114,000?t of galena, 638?t of silver sulphides and 6.5?t of gold.

  12. The effects of different carbon sources on microbial mediation of arsenic in arsenic-contaminated sediment

    Microsoft Academic Search

    Jong-Un Lee; Sang-Woo Lee; Kyoung-Woong Kim; Chung-Han Yoon

    2005-01-01

    Changes in speciation and mobility of As by indigenous bacteria in As-contaminated sediments (339 mg\\/kg) from an abandoned\\u000a Au–Ag mine area in Korea were investigated after biostimulation with a variety of carbon sources, including acetate, lactate\\u000a and glucose in batch experiments. Sequential extraction analysis designed to determine the form of As occurrence revealed\\u000a that 40 and 47% of As were present

  13. Bioremediation of mixed microbial mats: System development of mixed contaminants for application at the Savannah River Site. Annual technical progress report, October 1, 1995--September 30, 1996

    SciTech Connect

    Bender, J.; Phillips, P.

    1996-09-24

    The fundamental objective of this project is to develop and field test the mixed microbial mat bioremediation system for decontamination of target sites at SRS. Although microbial mats have performed well in several pilot projects in the past, atypical problems and site characteristics at SRS demand special field designs. In the interest of designing a pilot and locating it at an appropriate site, the project investigators have worked closely with the technical staff at the SREL. We have concluded that the diverse characteristics of contaminations at SRS may dictate testing several pilot designs during the course of this project.

  14. Bacterial and archaeal communities in long-term contaminated surface and subsurface soil evaluated through coextracted RNA and DNA.

    PubMed

    Mikkonen, Anu; Santalahti, Minna; Lappi, Kaisa; Pulkkinen, Anni-Mari; Montonen, Leone; Suominen, Leena

    2014-10-01

    Soil RNA and DNA were coextracted along a contamination gradient at a landfarming field with aged crude oil contamination to investigate pollution-dependent differences in 16S rRNA and rRNA gene pools. Microbial biomass correlated with nucleic acid yields as well as bacterial community change, indicating that the same factors controlled community size and structure. In surface soil, bacterial community evenness, estimated through length heterogeneity PCR (LH-PCR) fingerprinting, appeared higher for RNA-based than for DNA-based communities. The RNA-based community profiles resembled the DNA-based communities of soil with a lower contamination level. Cloning-based identification of bacterial hydrocarbon-degrading taxa in the RNA pool, representing the viable community with high protein synthesis potential, indicated that decontamination processes still continue. Analyses of archaea revealed that only Thaumarchaeota were present in the aerobic samples, whereas more diverse communities were found in the compacted subsurface soil with more crude oil. For subsurface bacteria, hydrocarbon concentration explained neither the community structure nor the difference between RNA-based and DNA-based communities. However, rRNA of bacterial taxa associated with syntrophic and sulphate-reducing alkane degradation was detected. Although the same prokaryotic taxa were identified in DNA and RNA, comparison of the two nucleic acid pools can aid in the assessment of past and future restoration success. PMID:24986450

  15. A Method for Selectively Enriching Microbial DNA from Contaminating Vertebrate Host DNA

    PubMed Central

    Feehery, George R.; Yigit, Erbay; Oyola, Samuel O.; Langhorst, Bradley W.; Schmidt, Victor T.; Stewart, Fiona J.; Dimalanta, Eileen T.; Amaral-Zettler, Linda A.; Davis, Theodore; Quail, Michael A.; Pradhan, Sriharsa

    2013-01-01

    DNA samples derived from vertebrate skin, bodily cavities and body fluids contain both host and microbial DNA; the latter often present as a minor component. Consequently, DNA sequencing of a microbiome sample frequently yields reads originating from the microbe(s) of interest, but with a vast excess of host genome-derived reads. In this study, we used a methyl-CpG binding domain (MBD) to separate methylated host DNA from microbial DNA based on differences in CpG methylation density. MBD fused to the Fc region of a human antibody (MBD-Fc) binds strongly to protein A paramagnetic beads, forming an effective one-step enrichment complex that was used to remove human or fish host DNA from bacterial and protistan DNA for subsequent sequencing and analysis. We report enrichment of DNA samples from human saliva, human blood, a mock malaria-infected blood sample and a black molly fish. When reads were mapped to reference genomes, sequence reads aligning to host genomes decreased 50-fold, while bacterial and Plasmodium DNA sequences reads increased 8–11.5-fold. The Shannon-Wiener diversity index was calculated for 149 bacterial species in saliva before and after enrichment. Unenriched saliva had an index of 4.72, while the enriched sample had an index of 4.80. The similarity of these indices demonstrates that bacterial species diversity and relative phylotype abundance remain conserved in enriched samples. Enrichment using the MBD-Fc method holds promise for targeted microbiome sequence analysis across a broad range of sample types. PMID:24204593

  16. Effects of cleaning and disinfection in reducing the spread of Norovirus contamination via environmental surfaces

    Microsoft Academic Search

    J. Barker; I. B. Vipond; S. F. Bloomfield

    2004-01-01

    A reverse transcriptase polymerase chain reaction assay was used to study the transfer of Norovirus (NV) from contaminated faecal material via fingers and cloths to other hand-contact surfaces. The results showed that, where fingers come into contact with virus-contaminated material, NV is consistently transferred via the fingers to melamine surfaces and from there to other typical hand-contact surfaces, such as

  17. Development of equations to estimate microbial contamination in ruminal incubation residues of forage produced under tropical conditions using 15N as a label.

    PubMed

    Machado, P A S; Valadares Filho, S C; Detmann, E; Santos, S A; Valadares, R F D; Ducatti, C; Rotta, P P; Costa e Silva, L F

    2013-08-01

    The objective of this study was to use (15)N to label microbial cells to allow development of equations for estimating the microbial contamination in ruminal in situ incubation residues of forage produced under tropical conditions. A total of 24 tropical forages were ruminal incubated in 3 steers at 3 separate times. To determine microbial contamination of the incubated residues, ruminal bacteria were labeled with (15)N by continuous intraruminal infusion 60 h before the first incubation and continued until the last day of incubation. Ruminal digesta was collected for the isolation of bacteria before the first infusion of (15)N on adaptation period and after the infusion of (15)N on collection period. To determine the microbial contamination of CP fractions, restricted models were compared with the full model using the model identity test. A value of the corrected fraction "A" was estimated from the corresponding noncorrected fraction by this equation: Corrected "A" fraction (A(CP)C) = 1.99286 + 0.98256 × A" fraction without correction (A(CP)WC). The corrected fraction "B" was estimated from the corresponding noncorrected fraction and from CP, NDF, neutral detergent insoluble protein (NDIP), and indigestible NDF (iNDF) using the equation corrected "B" fraction (B(CP)C) = -17.2181 - 0.0344 × fraction "B" without correction (B(CP)WC) + 0.65433 × CP + 1.03787 × NDF + 2.66010 × NDIP - 0.85979 × iNDF. The corrected degradation rate of "B" fraction (kd)was estimated using the equation corrected degradation rate of "B" fraction (kd(CP)C) = 0.04667 + 0.35139 × degradation rate of "B" fraction without correction (kd(CP)WC) + 0.0020 × CP - 0.00055839 × NDF - 0.00336 × NDIP + 0.00075089 × iNDF. This equation was obtained to estimate the contamination using CP of the feeds: %C = 79.21 × (1 - e(-0.0555t)) × e(-0.0874CP). It was concluded that A and B fractions and kd of CP could be highly biased by microbial CP contamination, and therefore these corrected values could be obtained mathematically, replacing the use of microbial markers. The percentage of contamination and the corrected apparent degradability of CP could be obtained from values of CP and time of incubation for each feed, which could reduce cost and labor involved when using (15)N. PMID:23658352

  18. Transport of microbial tracers in clean and organically contaminated silica sand in laboratory columns compared with their transport in the field.

    PubMed

    Weaver, Louise; Sinton, Lester W; Pang, Liping; Dann, Rod; Close, Murray

    2013-01-15

    Waste disposal on land and the consequent transport of bacterial and viral pathogens in soils and aquifers are of major concern worldwide. Pathogen transport can be enhanced in the presence of organic matter due to occupation of attachment sites in the aquifer materials thus preventing pathogen attachment leading to their faster transport for longer distances. Laboratory column studies were carried out to investigate the effect of organic matter, in the form of dissolved organic carbon (DOC), on the transport of Escherichia coli and MS2 phage in saturated clean silica sand. Transport rates of these microbial tracers were also studied in a contaminated field site. Laboratory column studies showed that low concentrations (0.17 mg L(-1)) of DOC had little effect on E. coli J6-2 removal and slightly reduced the attachment of MS2 phage. After progressive conditioning of the column with DOC (1.7 mg L(-1) and 17 mg L(-1)), neither E. coli J6-2 nor MS2 phage showed any attachment and recovery rates increased dramatically (up to 100%). The results suggest that DOC can affect the transport rates of microbial contaminants. For E. coli J6-2 the predominant effect appeared to be an increase in the secondary energy minimum leading to an increase in E. coli attachment initially. However, after 17 mg L(-1) DOC conditioning of the silica sand no attachment of E. coli was observed as the DOC took up attachment sites in the porous media. MS2 phage appeared to be affected predominantly by out-competition of binding sites in the clean silica sand and a steady reduction in attachment was observed as the DOC conditioning increased. Field study showed a high removal of both E. coli and MS2 phage, although E. coli was removed at a lower rate than MS2 phage. In the field it is likely that a combination of effects are seen as the aquifer material will be heterogeneous in its surface nanoscale properties, demonstrated by the differing removal of E. coli and MS2 phage compared to the laboratory scale experiments. This research demonstrates the importance of combining laboratory scale and field scale studies to fully understand removal of microbes in groundwater aquifers affected by organic matter (DOC). PMID:23178890

  19. A limited microbial consortium is responsible for longer-term biostimulation and bioreduction or uranium in a contaminated aquifer

    SciTech Connect

    Gihring, Thomas [ORNL; Zhang, Gengxin [ORNL; Brandt, Craig C [ORNL; Brooks, Scott C [ORNL; Carroll, Sue L [ORNL; Criddle, Craig [Stanford University; Green, Stefan [Florida State University; Jardine, Philip M [ORNL; Kostka, Joel [Florida State University; Lowe, Kenneth Alan [ORNL; Mehlhorn, Tonia L [ORNL; Overholt, Will [Florida State University; Watson, David B [ORNL; Yang, Zamin [ORNL; Wu, Wei-min [Stanford University; Schadt, Christopher Warren [ORNL

    2011-01-01

    Subsurface amendments of slow-release substrates (e.g., emulsified vegetable oil [EVO]) are thought to be a pragmatic alternative to using short-lived, labile substrates for sustained uranium bioimmobilization within contaminated groundwater systems. Spatial and temporal dynamics of subsurface microbial communities during EVO amendment are unknown and likely differ significantly from those of populations stimulated by soluble substrates, such as ethanol and acetate. In this study, a one-time EVO injection resulted in decreased groundwater U concentrations that remained below initial levels for approximately 4 months. Pyrosequencing and quantitative PCR of 16S rRNA from monitoring well samples revealed a rapid decline in groundwater bacterial community richness and diversity after EVO injection, concurrent with increased 16S rRNA copy levels, indicating the selection of a narrow group of taxa rather than a broad community stimulation. Members of the Firmicutes family Veillonellaceae dominated after injection and most likely catalyzed the initial oil decomposition. Sulfate-reducing bacteria from the genus Desulforegula, known for long-chain fatty acid oxidation to acetate, also dominated after EVO amendment. Acetate and H{sub 2} production during EVO degradation appeared to stimulate NO{sub 3}{sup -}, Fe(III), U(VI), and SO{sub 4}{sup 2-} reduction by members of the Comamonadaceae, Geobacteriaceae, and Desulfobacterales. Methanogenic archaea flourished late to comprise over 25% of the total microbial community. Bacterial diversity rebounded after 9 months, although community compositions remained distinct from the preamendment conditions. These results demonstrated that a one-time EVO amendment served as an effective electron donor source for in situ U(VI) bioreduction and that subsurface EVO degradation and metal reduction were likely mediated by successive identifiable guilds of organisms.

  20. Contaminant Interferences with SIMS Analyses of Microparticle Impactor Residues on LDEF Surfaces

    NASA Technical Reports Server (NTRS)

    Simon, C. G.; Batchelor, D.; Griffis, D. P.; Hunter, J. L.; Misra, V.; Ricks, D. A.; Wortman, J. J.

    1992-01-01

    Elemental analyses of impactor residues on high purity surface exposed to the low earth orbit (LEO) environment for 5.8 years on Long Duration Exposure Facility (LDEF) has revealed several probable sources for microparticles at this altitude, including natural micrometeorites and manmade debris ranging from paint pigments to bits of stainless steel. A myriad of contamination interferences were identified and their effects on impactor debris identification mitigated during the course of this study. These interferences included pre-, post-, and in-flight deposited particulate surface contaminants, as well as indigenous heterogeneous material contaminants. Non-flight contaminants traced to human origins, including spittle and skin oils, contributed significant levels of alkali-rich carbonaceous interferences. A ubiquitous layer of in-flight deposited silicaceous contamination varied in thickness with location on LDEF and proximity to active electrical fields. In-flight deposited (low velocity) contaminants included urine droplets and bits of metal film from eroded thermal blankets.

  1. Contaminant interferences with SIMS analyses of microparticle impactor residues on LDEF surfaces

    NASA Astrophysics Data System (ADS)

    Simon, C. G.; Batchelor, D.; Griffis, D. P.; Hunter, J. L.; Misra, V.; Ricks, D. A.; Wortman, J. J.

    1993-08-01

    Elemental analyses of impactor residues on high purity surfaces exposed to the LEO environment for 5.8 years on LDEF has revealed several probable sources for microparticles at this altitude, including natural micrometeorites and manmade debris ranging from paint pigments to bits of stainless steel. A myriad of contamination interferences were identified and their effects on impactor debris identification mitigated during the course of this study. These interferences included pre-, post- and in-flight deposited particulate surface contaminants, as well as indigenous heterogeneous material contaminants. Non-flight contaminants traced to human origins, including spittle and skin oils, contributed significant levels of alkali-rich carbonaceous interferences. A ubiquitous layer of in-flight deposited silicaceous contamination varied in thickness with LDEF location and proximity to active electrical fields. In-flight deposited (low velocity) contaminants included urine droplets and bits of metal film from eroded thermal blankets.

  2. MICELLE FORMATION AND SURFACE INTERACTIONS IN SUPERCRITICAL CO2: FUNDAMENTAL STUDIES FOR THE EXTRACTION OF ACTINIDES FROM CONTAMINATED SURFACES

    EPA Science Inventory

    The goal of this research was to build a fundamental understanding of microemulsion formation and mobility in supercritical CO2 necessary to develop an innovative extraction system for selectively removing metals (actinides) from contaminated surfaces. The goals included (1) stud...

  3. MICELLE FORMATION AND SURFACE INTERACTIONS IN SUPERCRITICAL CO2: FUNDAMENTAL STUDIES FOR THE EXTRACTION OF ACTINIDES FROM CONTAMINATED SURFACES

    EPA Science Inventory

    This research seeks to build the fundamental understanding of micelle formation and mobility in supercritical CO2, necessary to develop an innovative phase-transfer extraction system for selectively removing metals (actinides) from contaminated surfaces. We will extract metal ion...

  4. Effect of Microscale Surface Geometry of Electrodes on Performance of Microbial Fuel Cells

    NASA Astrophysics Data System (ADS)

    Kano, Tomonori; Suito, Eiichi; Hishida, Koichi; Miki, Norihisa

    2012-06-01

    In this study, we experimentally revealed that the microscale surface geometry of anodes strongly affects the performance of microbial fuel cells (MFCs). MFCs have much need to be improved in their power. The power generated by an MFC is considered to be strongly affected by the interaction between the organic bacteria and the inorganic electrode surfaces. In prior work, the nanoscale surface roughness of the anode was discussed; however, we consider that the microscale surface geometry may play a crucial role given the bacteria size of micrometer order. We used a two-chamber MFC and the direct electron transfer bacteria Shewanella putrefaciens. We prepared seven types of anode electrodes with different microscale surface geometries and experimentally found that the MFC performance depended on the contact area between the bacteria and the anode. The MFC generated the maximum power when the contact area between the anode and bacteria was the largest.

  5. Microbial links between sulfate reduction and metal retention in uranium- and heavy metal-contaminated soil.

    PubMed

    Sitte, Jana; Akob, Denise M; Kaufmann, Christian; Finster, Kai; Banerjee, Dipanjan; Burkhardt, Eva-Maria; Kostka, Joel E; Scheinost, Andreas C; Büchel, Georg; Küsel, Kirsten

    2010-05-01

    Sulfate-reducing bacteria (SRB) can affect metal mobility either directly by reductive transformation of metal ions, e.g., uranium, into their insoluble forms or indirectly by formation of metal sulfides. This study evaluated in situ and biostimulated activity of SRB in groundwater-influenced soils from a creek bank contaminated with heavy metals and radionuclides within the former uranium mining district of Ronneburg, Germany. In situ activity of SRB, measured by the (35)SO(4)(2-) radiotracer method, was restricted to reduced soil horizons with rates of < or =142 +/- 20 nmol cm(-3) day(-1). Concentrations of heavy metals were enriched in the solid phase of the reduced horizons, whereas pore water concentrations were low. X-ray absorption near-edge structure (XANES) measurements demonstrated that approximately 80% of uranium was present as reduced uranium but appeared to occur as a sorbed complex. Soil-based dsrAB clone libraries were dominated by sequences affiliated with members of the Desulfobacterales but also the Desulfovibrionales, Syntrophobacteraceae, and Clostridiales. [(13)C]acetate- and [(13)C]lactate-biostimulated soil microcosms were dominated by sulfate and Fe(III) reduction. These processes were associated with enrichment of SRB and Geobacteraceae; enriched SRB were closely related to organisms detected in soils by using the dsrAB marker. Concentrations of soluble nickel, cobalt, and occasionally zinc declined < or =100% during anoxic soil incubations. In contrast to results in other studies, soluble uranium increased in carbon-amended treatments, reaching < or =1,407 nM in solution. Our results suggest that (i) ongoing sulfate reduction in contaminated soil resulted in in situ metal attenuation and (ii) the fate of uranium mobility is not predictable and may lead to downstream contamination of adjacent ecosystems. PMID:20363796

  6. Hybridization Analysis of Microbial DNA from Fuel Oil–Contaminated and Noncontaminated Soil

    Microsoft Academic Search

    C. Guo; W. Sun; J. B. Harsh; A. Ogram

    1997-01-01

    The enrichment of several genes (xylE, nahAcd, todC1C2BA, tmoABCDE, alkB) that encode enzymes responsible for key steps in the degradation of hydrocarbons, and one gene specific to rRNA group I\\u000a of the genus Pseudomonas, was studied in DNA extracted from a fuel oil–contaminated field site, and in laboratory microcosms (with the exception of\\u000a alkB). Toluene, ethylbenzene, xylene, and naphthalene concentrations

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

    SciTech Connect

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

    2009-05-01

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

  8. Effects of PCB Substrate Surface Finish, Flux, and Phosphorus Content on Ionic Contamination

    NASA Astrophysics Data System (ADS)

    Bacior, M.; Sobczak, N.; Siewiorek, A.; Kudyba, A.; Homa, M.; Nowak, R.; Dziula, M.; Mas?o?, S.

    2015-02-01

    The ionic contamination on printed circuit boards (PCB) having different surface finishes was examined using ionograph. The study was performed at the RT on three types of PCBs covered with: (i) hot air solder leveling (HASL LF), (ii) electroless nickel immersion gold (ENIG), and (iii) organic surface protectant (OSP), all on Cu substrates, as well as two types of fluxes, namely EF2202 and RF800. In the group of boards without soldered components, the lowest average value of contamination was for the ENIG 18 µm surface (0.01 ?g NaCl/cm2). Boards with soldered components were more contaminated (from 0.29 ?g NaCl/cm2 for the HASL LF 18 µm surface). After spraying boards with fluxing agents, the values of contaminants were the highest. The influence of phosphorus content in Ni-P layer of ENIG finish on ionic contamination was examined. In the group of PCBs with Au coating, the smallest amount of surface contaminants (0.32 ?g NaCl/cm2) was for Ni-2-5%P layer. PCBs with Ni-11%P layer were higher contaminated (0.47 ?g NaCl/cm2), and another with Ni-8%P layer had 0.81 ?g NaCl/cm2. PCBs without Au coating, had the lowest contamination (0.48 ?g NaCl/cm2) at phosphorous content equal 11%P. Higher contamination (0.67 ?g NaCl/cm2) was at 2-5%P, up to 1.98 ?g NaCl/cm2 for 8% of P. Boards with Au finish have lower value of contamination than identical boards without Au layer thus contributing to better reliability of electronic assemblies, since its failures due to current leakage and corrosion can be caused by contaminants.

  9. Fundamental study on an electret dosimeter for a surface contamination monitor

    SciTech Connect

    Uda, T.; Ohtsuka, H.; Ozawa, Y.

    1985-11-01

    To develop a convenient and sensitive surface contamination monitoring system, the feasibilities of an electret dosimeter using a thin polymer electret and piezoelectret sensor have been examined. To reduce the amounts of radioactive wastes, major interest has recently turned to the low-level radioactive wastes for which the contamination level is less than the de minimis level, which allows treatment as reusable waste. While official de minimis levels have not been set, average levels are presumed to be 10/sup -6/ and 10/sup -4/ ..mu..Ci/g for alpha and gamma contamination, respectively. The regulatory unit is the weight of radioactivity, but alpha contamination cannot be measured without a surface value. So the authors examined a surface contamination monitor, which was particularly suited to alpha measurements. Although electret dosimeters have been developed of the ion chamber type, the electret dosimeter using only a polymer foil was investigated.

  10. Laboratory Studies on Surface Sampling of Bacillus anthracis Contamination: Summary, Gaps, and Recommendations

    SciTech Connect

    Piepel, Gregory F.; Amidan, Brett G.; Hu, Rebecca

    2011-11-28

    This report summarizes previous laboratory studies to characterize the performance of methods for collecting, storing/transporting, processing, and analyzing samples from surfaces contaminated by Bacillus anthracis or related surrogates. The focus is on plate culture and count estimates of surface contamination for swab, wipe, and vacuum samples of porous and nonporous surfaces. Summaries of the previous studies and their results were assessed to identify gaps in information needed as inputs to calculate key parameters critical to risk management in biothreat incidents. One key parameter is the number of samples needed to make characterization or clearance decisions with specified statistical confidence. Other key parameters include the ability to calculate, following contamination incidents, the (1) estimates of Bacillus anthracis contamination, as well as the bias and uncertainties in the estimates, and (2) confidence in characterization and clearance decisions for contaminated or decontaminated buildings. Gaps in knowledge and understanding identified during the summary of the studies are discussed and recommendations are given for future studies.

  11. Profenofos insecticide degradation by novel microbial consortium and isolates enriched from contaminated chili farm soil.

    PubMed

    Siripattanakul-Ratpukdi, Sumana; Vangnai, Alisa S; Sangthean, Puttaporn; Singkibut, Sirinuttakan

    2015-01-01

    Profenofos (PF) is one of the heavily used organophosphorus pesticides (OPPs) of which its contamination is ubiquitous in an agricultural area. This study aims to acquire and characterize PF-degrading bacterial cultures from contaminated soil. OPP degradation by the novel isolates was then investigated. The experiment was performed at the initial PF concentration of 20 mg/L. The result showed that the enriched consortium comprised three predominant PF-degrading strains designated as PF1, PF2, and PF3. The isolates (PF1, PF2, and PF3) were characterized as Pseudomonas plecoglossicida, Pseudomonas aeruginosa, and P. aeruginosa, respectively. A consortium and all isolates could utilize PF as a sole carbon source with PF removal of more than 90% via a hydrolysis process. The bacterial growth and PF degradation rates followed the first-order kinetic reaction with the rates of 0.4 to 2.7/h and 0.15 to 1.96/h, respectively. Additional carbon supplement deteriorated PF biodegradation. The enriched cultures were also capable for degrading chlorpyrifos and dicrotophos pesticides (33-73% removal). The results indicated that the consortium and isolates are efficient for PF and other OPP degradation and have potential for PF remediation. PMID:25065481

  12. Isolation of PCR quality microbial community DNA from heavily contaminated environments.

    PubMed

    Gunawardana, Manjula; Chang, Simon; Jimenez, Abraham; Holland-Moritz, Daniel; Holland-Moritz, Hannah; La Val, Taylor P; Lund, Craig; Mullen, Madeline; Olsen, John; Sztain, Terra A; Yoo, Jennifer; Moss, John A; Baum, Marc M

    2014-07-01

    Asphalts, biochemically degraded oil, contain persistent, water-soluble compounds that pose a significant challenge to the isolation of PCR quality DNA. The adaptation of existing DNA purification protocols and commercial kits proved unsuccessful at overcoming this hurdle. Treatment of aqueous asphalt extracts with a polyamide resin afforded genomic microbial DNA templates that could readily be amplified by PCR. Physicochemically distinct asphalt samples from five natural oil seeps successfully generated the expected 291 bp amplicons targeting a region of the 16S rRNA gene, illustrating the robustness of the method. DNA recovery yields were in the 50-80% range depending on how the asphalt sample was seeded with exogenous DNA. The scope of the new method was expanded to include soil with high humic acid content. DNA from soil samples spiked with a range of humic acid concentrations was extracted with a commercial kit followed by treatment with the polyamide resin. The additional step significantly improved the purity of the DNA templates, especially at high humic acid concentrations, based on qPCR analysis of the bacterial 16S rRNA genes. The new method has the advantages of being inexpensive, simple, and rapid and should provide a valuable addition to protocols in the field of petroleum and soil microbiology. PMID:24769406

  13. Reduction of Contaminants (Physical, Chemical, and Microbial) in Domestic Wastewater through Hybrid Constructed Wetland

    PubMed Central

    Sehar, Shama; Aamir, Rabia; Naz, Iffat; Ali, Naeem; Ahmed, Safia

    2013-01-01

    The current research was focused mainly on the designing and construction of efficient laboratory scale hybrid constructed wetland (HCW) for the treatment of domestic wastewater. Parameters like COD, BOD5, PO4, SO4, NO3, NO2, and pathogenic indicator microbes were monitored after hydraulic retention time (HRT) of 4, 8, 12, 16, and 20 days. Treatment efficiency of HCW kept on increasing with the increase in hydraulic retention time. Maximum efficiency of HCW was observed with a 20-day HRT, that is, 97.55, 97.5, 89.35, 80.75, 96.04, 91.52, and 98.6% reduction from the zero time value for COD, BOD5, PO4, SO4, NO3, NO2, and fecal coliforms, respectively. After 20 days' time, the treated water was free of almost all nutrients and microbial pollutants. Hence, increasing hydraulic retention time was found to ameliorate the operational competence of HCW. Thus HCW can serve as a promising technology for wastewater treatment and can be scaled up for small communities in the developing countries. PMID:23724336

  14. A combined approach to assess the microbial contamination of the archimedes palimpsest.

    PubMed

    Piñar, Guadalupe; Sterflinger, Katja; Ettenauer, Jörg; Quandt, Abigail; Pinzari, Flavia

    2015-01-01

    A combined approach, using molecular and microscopic techniques, was used to identify the microbiota associated with the Archimedes Palimpsest, an unusual parchment manuscript. SEM analyses revealed the microbial damage to the collagen fibers and the presence of characteristic cell chains typical of filamentous bacteria and fungal spores. Molecular analysis confirmed a homogeneous bacterial community colonizing the manuscript. The phyla Proteobacteria and Actinobacteria were associated with this ancient parchment; the sequences were most related to uncultured clones detected in the human skin microbiome and in ephitelium, and to cultivated species of the genera Acinetobacter and Nocardiopsis. Nevertheless, a great variation was observed among the different sampled areas indicating fungal diversity. Blumeria spp. dominated in the healthy areas of the parchment while degraded areas showed disparate fungal communities, with dominant members of the genera Mucor and Cladosporium. In addition, the quantification of the ?-actin gene by real-time PCR analyses (qPCR) revealed a higher fungal abundance on degraded areas than on the healthy ones. PMID:25135817

  15. ARSENIC SORUCE IDENTIFICATION AT THE GROUND WATER-SURFACE WATER INTERACTION ZONE AT A CONTAMINATED SITE

    EPA Science Inventory

    One of the challenges in assessing the current impact of the discharge of arsenic contaminated ground water into a surface water body is differentiating the arsenic ground-water flux versus dissolution of in-place contaminated sediments. A field investigation has been carried ou...

  16. FIELD STUDIES AND MODELING APPROACHES FOR PREDICTING ENTRY OF CONTAMINANTS INTO SURFACE WATERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Consumption and contamination of surface and groundwater by agriculture may put farming in conflict with other human and ecological needs for the same resource. Some water contamination is accidental, or the result of human error. However, even if such incidents were eliminated, proper and correct ...

  17. Advection of surface-derived organic carbon fuels microbial reduction in Bangladesh groundwater.

    PubMed

    Mailloux, Brian J; Trembath-Reichert, Elizabeth; Cheung, Jennifer; Watson, Marlena; Stute, Martin; Freyer, Greg A; Ferguson, Andrew S; Ahmed, Kazi Matin; Alam, Md Jahangir; Buchholz, Bruce A; Thomas, James; Layton, Alice C; Zheng, Yan; Bostick, Benjamin C; van Geen, Alexander

    2013-04-01

    Chronic exposure to arsenic (As) by drinking shallow groundwater causes widespread disease in Bangladesh and neighboring countries. The release of As naturally present in sediment to groundwater has been linked to the reductive dissolution of iron oxides coupled to the microbial respiration of organic carbon (OC). The source of OC driving this microbial reduction--carbon deposited with the sediments or exogenous carbon transported by groundwater--is still debated despite its importance in regulating aquifer redox status and groundwater As levels. Here, we used the radiocarbon ((14)C) signature of microbial DNA isolated from groundwater samples to determine the relative importance of surface and sediment-derived OC. Three DNA samples collected from the shallow, high-As aquifer and one sample from the underlying, low-As aquifer were consistently younger than the total sediment carbon, by as much as several thousand years. This difference and the dominance of heterotrophic microorganisms implies that younger, surface-derived OC is advected within the aquifer, albeit more slowly than groundwater, and represents a critical pool of OC for aquifer microbial communities. The vertical profile shows that downward transport of dissolved OC is occurring on anthropogenic timescales, but bomb (14)C-labeled dissolved OC has not yet accumulated in DNA and is not fueling reduction. These results indicate that advected OC controls aquifer redox status and confirm that As release is a natural process that predates human perturbations to groundwater flow. Anthropogenic perturbations, however, could affect groundwater redox conditions and As levels in the future. PMID:23487743

  18. Advection of surface-derived organic carbon fuels microbial reduction in Bangladesh groundwater

    PubMed Central

    Mailloux, Brian J.; Trembath-Reichert, Elizabeth; Cheung, Jennifer; Watson, Marlena; Stute, Martin; Freyer, Greg A.; Ferguson, Andrew S.; Ahmed, Kazi Matin; Alam, Md. Jahangir; Buchholz, Bruce A.; Thomas, James; Layton, Alice C.; Zheng, Yan; Bostick, Benjamin C.; van Geen, Alexander

    2013-01-01

    Chronic exposure to arsenic (As) by drinking shallow groundwater causes widespread disease in Bangladesh and neighboring countries. The release of As naturally present in sediment to groundwater has been linked to the reductive dissolution of iron oxides coupled to the microbial respiration of organic carbon (OC). The source of OC driving this microbial reduction—carbon deposited with the sediments or exogenous carbon transported by groundwater—is still debated despite its importance in regulating aquifer redox status and groundwater As levels. Here, we used the radiocarbon (14C) signature of microbial DNA isolated from groundwater samples to determine the relative importance of surface and sediment-derived OC. Three DNA samples collected from the shallow, high-As aquifer and one sample from the underlying, low-As aquifer were consistently younger than the total sediment carbon, by as much as several thousand years. This difference and the dominance of heterotrophic microorganisms implies that younger, surface-derived OC is advected within the aquifer, albeit more slowly than groundwater, and represents a critical pool of OC for aquifer microbial communities. The vertical profile shows that downward transport of dissolved OC is occurring on anthropogenic timescales, but bomb 14C-labeled dissolved OC has not yet accumulated in DNA and is not fueling reduction. These results indicate that advected OC controls aquifer redox status and confirm that As release is a natural process that predates human perturbations to groundwater flow. Anthropogenic perturbations, however, could affect groundwater redox conditions and As levels in the future. PMID:23487743

  19. Microbial communities and functional genes associated with soil arsenic contamination and the rhizosphere of the arsenic-hyperaccumulating plant Pteris vittata L.

    PubMed

    Xiong, Jinbo; Wu, Liyou; Tu, Shuxin; Van Nostrand, Joy D; He, Zhili; Zhou, Jizhong; Wang, Gejiao

    2010-11-01

    To understand how microbial communities and functional genes respond to arsenic contamination in the rhizosphere of Pteris vittata, five soil samples with different arsenic contamination levels were collected from the rhizosphere of P. vittata and nonrhizosphere areas and investigated by Biolog, geochemical, and functional gene microarray (GeoChip 3.0) analyses. Biolog analysis revealed that the uncontaminated soil harbored the greatest diversity of sole-carbon utilization abilities and that arsenic contamination decreased the metabolic diversity, while rhizosphere soils had higher metabolic diversities than did the nonrhizosphere soils. GeoChip 3.0 analysis showed low proportions of overlapping genes across the five soil samples (16.52% to 45.75%). The uncontaminated soil had a higher heterogeneity and more unique genes (48.09%) than did the arsenic-contaminated soils. Arsenic resistance, sulfur reduction, phosphorus utilization, and denitrification genes were remarkably distinct between P. vittata rhizosphere and nonrhizosphere soils, which provides evidence for a strong linkage among the level of arsenic contamination, the rhizosphere, and the functional gene distribution. Canonical correspondence analysis (CCA) revealed that arsenic is the main driver in reducing the soil functional gene diversity; however, organic matter and phosphorus also have significant effects on the soil microbial community structure. The results implied that rhizobacteria play an important role during soil arsenic uptake and hyperaccumulation processes of P. vittata. PMID:20833780

  20. Microbial mineralization of cis-dichloroethene and vinyl chloride as a component of natural attenuation of chloroethene contaminants under conditions identified in the field as anoxic

    USGS Publications Warehouse

    Bradley, Paul M.

    2012-01-01

    Chlororespiration is a key component of remediation at many chloroethene-contaminated sites. In some instances, limited accumulation of reductive dechlorination daughter products may suggest that natural attenuation is not adequate for site remediation. This conclusion is justified when evidence for parent compound (tetrachloroethene, PCE, or trichloroethene, TCE) degradation is lacking. For many chloroethene-contaminated shallow aquifer systems, however, non-conservative losses of the parent compounds are clear but the mass balance between parent compound attenuation and accumulation of reductive dechlorination daughter products is incomplete. Incomplete mass balance indicates a failure to account for important contaminant attenuation mechanisms, and is consistent with contaminant degradation to non-diagnostic mineralization products. An ongoing technical debate over the potential for mineralization of dichloroethene (DCE) and vinyl chloride (VC) to CO2 in the complete absence of diatomic oxygen has largely obscured the importance of microbial DCE/VC mineralization at dissolved oxygen (DO) concentrations below the current field standard (DO < 0.1-0.5 milligrams per liter) for nominally anoxic conditions. This study demonstrates that oxygen-based microbial mineralization of DCE and VC can be substantial under field conditions that are frequently characterized as "anoxic." Because mischaracterization of operant contaminant biodegradation processes can lead to expensive and ineffective remedial actions, a modified framework for assessing the potential importance of oxygen during chloroethene biodegradation was developed.

  1. Microbial Communities and Functional Genes Associated with Soil Arsenic Contamination and the Rhizosphere of the Arsenic-Hyperaccumulating Plant Pteris vittata L. ? †

    PubMed Central

    Xiong, Jinbo; Wu, Liyou; Tu, Shuxin; Van Nostrand, Joy D.; He, Zhili; Zhou, Jizhong; Wang, Gejiao

    2010-01-01

    To understand how microbial communities and functional genes respond to arsenic contamination in the rhizosphere of Pteris vittata, five soil samples with different arsenic contamination levels were collected from the rhizosphere of P. vittata and nonrhizosphere areas and investigated by Biolog, geochemical, and functional gene microarray (GeoChip 3.0) analyses. Biolog analysis revealed that the uncontaminated soil harbored the greatest diversity of sole-carbon utilization abilities and that arsenic contamination decreased the metabolic diversity, while rhizosphere soils had higher metabolic diversities than did the nonrhizosphere soils. GeoChip 3.0 analysis showed low proportions of overlapping genes across the five soil samples (16.52% to 45.75%). The uncontaminated soil had a higher heterogeneity and more unique genes (48.09%) than did the arsenic-contaminated soils. Arsenic resistance, sulfur reduction, phosphorus utilization, and denitrification genes were remarkably distinct between P. vittata rhizosphere and nonrhizosphere soils, which provides evidence for a strong linkage among the level of arsenic contamination, the rhizosphere, and the functional gene distribution. Canonical correspondence analysis (CCA) revealed that arsenic is the main driver in reducing the soil functional gene diversity; however, organic matter and phosphorus also have significant effects on the soil microbial community structure. The results implied that rhizobacteria play an important role during soil arsenic uptake and hyperaccumulation processes of P. vittata. PMID:20833780

  2. Microbial Mineral Transformations at the Fe(II)/Fe(III) Redox Boundary for Solid Phase Capture of Strontium and Other Metal/Radionuclide Contaminants

    SciTech Connect

    F. G. Ferris; E. E. Roden

    2000-01-31

    The migration of {sup 90}Sr in groundwater is a significant environmental concern at former nuclear weapons production sites in the US and abroad. Although retardation of {sup 90}Sr transport relative to mean groundwater velocity is known to occur in contaminated aquifers, Sr{sup 2+} does not sorb as strongly to iron oxides and other mineral phases as do other metal-radionuclides contaminants. Thus, some potential exists for extensive {sup 90}Sr migration from sources of contamination. Chemical or biological processes capable of retarding or immobilizing Sr{sup 2+} in groundwater environments are of interest from the standpoint of understanding controls on subsurface Sr{sup 2+} migration. In addition, it may be possible to exploit such processes for remediation of subsurface Sr contamination. In this study the authors examined the potential for the solid phase sorption and incorporation of Sr{sup 2+} into carbonate minerals formed during microbial Fe(III) oxide reduction as a first step toward evaluating whether this process could be used to promote retardation of {sup 90}Sr migrations in anaerobic subsurface environments. The demonstration of Sr{sup 2+} capture in carbonate mineral phases formed during bacterial HFO reduction and urea hydrolysis suggests that microbial carbonate mineral formation could contribute to Sr{sup 2+} retardation in groundwater environments. This process may also provide a mechanism for subsurface remediation of Sr{sup 2+} and other divalent metal contaminants that form insoluble carbonate precipitates.

  3. Enhancement of the microbial community biomass and diversity during air sparging bioremediation of a soil highly contaminated with kerosene and BTEX

    Microsoft Academic Search

    Nadja Kabelitz; Jirina Machackova; Gwenaël Imfeld; Maria Brennerova; Dietmar H. Pieper; Hermann J. Heipieper; Howard Junca

    2009-01-01

    In order to obtain insights in complexity shifts taking place in natural microbial communities under strong selective pressure,\\u000a soils from a former air force base in the Czech Republic, highly contaminated with jet fuel and at different stages of a bioremediation\\u000a air sparging treatment, were analyzed. By tracking phospholipid fatty acids and 16S rRNA genes, a detailed monitoring of the

  4. Effect of different disinfection protocols on microbial and biofilm contamination of dental unit waterlines in community dental practices.

    PubMed

    Dallolio, Laura; Scuderi, Amalia; Rini, Maria S; Valente, Sabrina; Farruggia, Patrizia; Sabattini, Maria A Bucci; Pasquinelli, Gianandrea; Acacci, Anna; Roncarati, Greta; Leoni, Erica

    2014-02-01

    Output water from dental unit waterlines (DUWLs) may be a potential source of infection for both dental healthcare staff and patients. This study compared the efficacy of different disinfection methods with regard to the water quality and the presence of biofilm in DUWLs. Five dental units operating in a public dental health care setting were selected. The control dental unit had no disinfection system; two were disinfected intermittently with peracetic acid/hydrogen peroxide 0.26% and two underwent continuous disinfection with hydrogen peroxide/silver ions (0.02%) and stabilized chlorine dioxide (0.22%), respectively. After three months of applying the disinfection protocols, continuous disinfection systems were more effective than intermittent systems in reducing the microbial contamination of the water, allowing compliance with the CDC guidelines and the European Council regulatory thresholds for drinking water. P. aeruginosa, Legionella spp, sulphite-reducing Clostridium spores, S. aureus and ?-haemolytic streptococci were also absent from units treated with continuous disinfection. The biofilm covering the DUWLs was more extensive, thicker and more friable in the intermittent disinfection dental units than in those with continuous disinfection. Overall, the findings showed that the products used for continuous disinfection of dental unit waterlines showed statistically better results than the intermittent treatment products under the study conditions. PMID:24552789

  5. Biodegradation Processes in a Laboratory-Scale Groundwater Contaminant Plume Assessed by Fluorescence Imaging and Microbial Analysis?

    PubMed Central

    Rees, Helen C.; Oswald, Sascha E.; Banwart, Steven A.; Pickup, Roger W.; Lerner, David N.

    2007-01-01

    Flow reactors containing quartz sand colonized with biofilm were set up as physical model aquifers to allow degrading plumes of acetate or phenol to be formed from a point source. A noninvasive fluorescent tracer technique was combined with chemical and biological sampling in order to quantify transport and biodegradation processes. Chemical analysis of samples showed a substantial decrease in carbon concentration between the injection and outflow resulting primarily from dilution but also from biodegradation. Two-dimensional imaging of the aqueous oxygen [O2(aq)] concentration field quantified the depletion of O2(aq) within the contaminant plume and provided evidence for microbial respiration associated with biodegradation of the carbon source. Combined microbiological, chemical, and O2(aq) imaging data indicated that biodegradation was greatest at the plume fringe. DNA profiles of bacterial communities were assessed by temperature gradient gel electrophoresis, which revealed that diversity was limited and that community changes observed depended on the carbon source used. Spatial variation in activity within the plume could be quantitatively accounted for by the changes observed in active cell numbers rather than differences in community structure, the total biomass present, or the increased enzyme activity of individual cells. Numerical simulations and comparisons with the experimental data were used to test conceptual models of plume processes. Results demonstrated that plume behavior was best described by growth and decay of active biomass as a single functional group of organisms represented by active cell counts. PMID:17468279

  6. Novel atmospheric pressure plasma device releasing atomic hydrogen: reduction of microbial-contaminants and OH radicals in the air

    NASA Astrophysics Data System (ADS)

    Nojima, Hideo; Park, Rae-Eun; Kwon, Jun-Hyoun; Suh, Inseon; Jeon, Junsang; Ha, Eunju; On, Hyeon-Ki; Kim, Hye-Ryung; Choi, Kyoung Hui; Lee, Kwang-Hee; Seong, Baik-Lin; Jung, Hoon; Kang, Shin Jung; Namba, Shinichi; Takiyama, Ken

    2007-01-01

    A novel atmospheric pressure plasma device releasing atomic hydrogen has been developed. This device has specific properties such as (1) deactivation of airborne microbial-contaminants, (2) neutralization of indoor OH radicals and (3) being harmless to the human body. It consists of a ceramic plate as a positive ion generation electrode and a needle-shaped electrode as an electron emission electrode. Release of atomic hydrogen from the device has been investigated by the spectroscopic method. Optical emission of atomic hydrogen probably due to recombination of positive ions, H+(H2O)n, generated from the ceramic plate electrode and electrons emitted from the needle-shaped electrode have been clearly observed in the He gas (including water vapour) environment. The efficacy of the device to reduce airborne concentrations of influenza virus, bacteria, mould fungi and allergens has been evaluated. 99.6% of airborne influenza virus has been deactivated with the operation of the device compared with the control test in a 1 m3 chamber after 60 min. The neutralization of the OH radical has been investigated by spectroscopic and biological methods. A remarkable reduction of the OH radical in the air by operation of the device has been observed by laser-induced fluorescence spectroscopy. The cell protection effects of the device against OH radicals in the air have been observed. Furthermore, the side effects have been checked by animal experiments. The harmlessness of the device has been confirmed.

  7. Effect of Different Disinfection Protocols on Microbial and Biofilm Contamination of Dental Unit Waterlines in Community Dental Practices

    PubMed Central

    Dallolio, Laura; Scuderi, Amalia; Rini, Maria S.; Valente, Sabrina; Farruggia, Patrizia; Bucci Sabattini, Maria A.; Pasquinelli, Gianandrea; Acacci, Anna; Roncarati, Greta; Leoni, Erica

    2014-01-01

    Output water from dental unit waterlines (DUWLs) may be a potential source of infection for both dental healthcare staff and patients. This study compared the efficacy of different disinfection methods with regard to the water quality and the presence of biofilm in DUWLs. Five dental units operating in a public dental health care setting were selected. The control dental unit had no disinfection system; two were disinfected intermittently with peracetic acid/hydrogen peroxide 0.26% and two underwent continuous disinfection with hydrogen peroxide/silver ions (0.02%) and stabilized chlorine dioxide (0.22%), respectively. After three months of applying the disinfection protocols, continuous disinfection systems were more effective than intermittent systems in reducing the microbial contamination of the water, allowing compliance with the CDC guidelines and the European Council regulatory thresholds for drinking water. P. aeruginosa, Legionella spp, sulphite-reducing Clostridium spores, S. aureus and ?-haemolytic streptococci were also absent from units treated with continuous disinfection. The biofilm covering the DUWLs was more extensive, thicker and more friable in the intermittent disinfection dental units than in those with continuous disinfection. Overall, the findings showed that the products used for continuous disinfection of dental unit waterlines showed statistically better results than the intermittent treatment products under the study conditions. PMID:24552789

  8. Microbial communities and biodegradation in lab-scale BTEX-contaminated groundwater remediation using an oxygen-releasing reactive barrier.

    PubMed

    Lin, Chi-Wen; Chen, Li-Hsuan; I, Yet-Pole; Lai, Chi-Yung

    2010-03-01

    To remediate benzene, toluene, ethylbenzene and xylene (BTEX) -contaminated groundwater, a biotreatment process including biostimulation and bioaugmentation was simulated using oxygen-releasing reactive barriers (ORRB) and water with added BTEX in a lab-scale system. The results showed that the capability for BTEX removal decreases in the order of benzene, toluene, p-xylene, ethylbenzene for both added-nitrogen and no-added-nitrogen under BTEX concentrations at 30 mg l(-1). The removal efficiencies in ORRB systems were higher in the nitrogen-added condition for biostimulation compared with the no-nitrogen-added condition; moreover, an increased pattern for removal was observed during the bioaugmentation process. The oxygen content was found to be inversely proportional to the distance from the ORRB, as evidenced by observing that the average bacteria densities were two orders higher when located at 15 cm compared with 30 cm from the ORRB. The microbial community structure was similar in both cases of added-nitrogen and the no-added-nitrogen conditions. PMID:19513757

  9. Spatial and temporal trends in surface water and sediment contamination in the Laurentian Great Lakes.

    PubMed

    Marvin, Chris; Painter, Scott; Williams, Donald; Richardson, Violeta; Rossmann, Ronald; Van Hoof, Patricia

    2004-05-01

    Data from recent sediment and surface water surveys have been collated and mapped to illustrate the spatial distribution of contaminants across the entire Great Lakes basin. Information from historical surveys, together with data from surface water monitoring programs in three major connecting channels, has also been collated in order to evaluate temporal trends. In general, Lakes Superior and Michigan exhibited the lowest levels of sediment contamination while Lake Ontario had the highest. Contaminants such as gamma-HCH (lindane) and dieldrin were ubiquitous in surface waters across the entire basin, which was indicative of atmospheric sources. The distribution of other compounds including hexachlorobenzene, octachlorostyrene and mirex indicated the presence of local sources within the watersheds of the connecting channels. Surficial sediment contamination was found to have decreased markedly since the late 1960s and 1970s. Similarly, surface water contamination decreased over the period 1986-1997 with concentrations of dieldrin, hexachlorobenzene, octachlorostyrene and mirex reduced by over 50%. However, the spatial distributions of both sediment and surface water contamination indicate that further effort is warranted in reducing local sources of contaminants, particularly in Lake Ontario. PMID:14749077

  10. Potential contribution of microbial degradation to natural attenuation of MTBE in surface water systems

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.; Landmeyer, J.E.

    2001-01-01

    The potential contribution of in situ biodegradation as a mechanism for natural attenuation of MTBE in surface water was studied. Surface water sediments from streams and lakes at 11 sites throughout the US. Microbial degradation of [U-14C] MTBE was observed in surface-water-sediment microcosms under anaerobic conditions, but the efficiency and products of anaerobic MTBE biodegradation were strongly dependent on the predominant terminal electron accepting conditions. In the presence of substantial methanogenic activity, MTBE biodegradation was nominal and involved reduction of MTBE to t-butanol (TBA). Under more oxidizing conditions, minimal accumulation of 14C-TBA and significant mineralization of [U-14C] MTBE to 14CO2 were observed. Microorganisms inhabiting the bed sediments of streams and lakes could degrade MTBE effectively under a range of anaerobic terminal electron accepting conditions. Thus, anaerobic bed sediment microbial processes also might contribute to natural attenuation of MTBE in surface water systems throughout the US. This is an abstract of a paper presented at the 222nd ACS National Meting (Chicago, IL 8/26-30/2001).

  11. DISTRIBUTION OF ORGANIC WASTEWATER CONTAMINANTS BETWEEN WATER AND SEDIMENT IN SURFACE WATERS OF THE UNITED STATES

    EPA Science Inventory

    Trace concentrations of pharmaceuticals and other organic wastewater contaminants have been determined in the surface waters of Europe and the United States. A preliminary report of substantially higher concentrations of pharmaceuticals in sediment suggests that bottom sediment ...

  12. Studies of Plume Condensation Contamination upon Surfaces of the Terrestrial Planet Finder Spacecraft

    E-print Network

    1 Studies of Plume Condensation Contamination upon Surfaces of the Terrestrial Planet Finder for the Terrestrial Planet Finder (TPF) mission, one which involves a single spacecraft, and another comprised

  13. A microwave-powered sterilizable interface for aseptic access to bioreactors that are vulnerable to microbial contamination

    NASA Technical Reports Server (NTRS)

    Atwater, J. E.; Michalek, W. F.; Wheeler, R. R. Jr; Dahl, R.; Lunsford, T. D.; Garmon, F. C.; Sauer, R. L.

    2001-01-01

    Novel methods and apparatus that employ the rapid heating characteristics of microwave irradiation to facilitate the aseptic transfer of nutrients, products, and other materials between microbially sensitive systems and the external environment are described. The microwave-sterilizable access port (MSAP) consists of a 600-W magnetron emitting at a frequency of 2.45 GHz, a sterilization chamber with inlet and outlet flow lines, and a specimen transfer interface. Energy is routed to the sterilization chamber via a coaxial transmission line where small quantities of water couple strongly with the incident radiation to produce a superheated vapor phase. The efficiency of energy transfer is enhanced through the use of microwave susceptors within the sterilization chamber. Mating surfaces are thermally sterilized through direct contact with the hot gas. Efficacy has been demonstrated using the thermophile Bacillus stearothermophilus.

  14. Contamination levels of human pharmaceutical compounds in French surface and drinking water

    E-print Network

    Paris-Sud XI, Université de

    Contamination levels of human pharmaceutical compounds in French surface and drinking water S therapeutic classes was analysed from resource and drinking water in two catchment basins located in north-west France. 98 samples were analysed from 63 stations (surface water and drinking water produced from surface

  15. Potable water production from pesticide contaminated surface water—A membrane based approach

    Microsoft Academic Search

    Baisali Sarkar; N. Venkateshwarlu; R. Nageswara Rao; Chiranjib Bhattacharjee; Vijay Kale

    2007-01-01

    The aim of the present study is to obtain safe and pure drinking water from surface water, which has been polluted with pesticide. Pesticide contaminated surface water samples were prepared by spiking commonly used pesticide, Isoproturon, in different surface water samples collected from different parts of India. Attempts were made to evaluate the efficiency of different adsorbents in removing pesticide

  16. Active cleaning techniques for removing contamination from optical surfaces in space

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.

    1973-01-01

    Research in developing an active cleaning technique for removing contaminants from optical surfaces in space is reported. In situ contamination/cleaning experiments were conducted on gold and platimum coated mirrors, which were contaminated by exposure to UV radiation in a 1,3, butadiene environment. Argon and oxygen plasma exposure cleaned the mirrors equally well. Silicone cleaning experiments were also conducted. Exposure of the contaminated mirrors to helium, oxygen, and hydrogen plasmas restored the reflectance at the shorter wavelengths and degraded it at the longer wavelengths.

  17. The effect of silver impregnation of surgical scrub suits on surface bacterial contamination

    Microsoft Academic Search

    A. I. Freeman; L. J. Halladay; P. Cripps

    Silver-impregnated fabrics are widely used for their antibacterial and antifungal effects, including for clinical clothing such as surgical scrub suits (scrubs). This study investigated whether silver impregnation reduces surface bacterial contamination of surgical scrubs during use in a veterinary hospital. Using agar contact plates, abdominal and lumbar areas of silver-impregnated nylon or polyester\\/cotton scrubs were sampled for surface bacterial contamination

  18. TECHNICAL BASIS FOR EVALUATING SURFACE BARRIERS TO PROTECT GROUNDWATER FROM DEEP VADOSE ZONE CONTAMINATION

    SciTech Connect

    FAYER JM; FREEDMAN VL; WARD AL; CHRONISTER GB

    2010-02-24

    The U.S. DOE and its predecessors released nearly 2 trillion liters (450 billion gallons) of contaminated liquid into the vadose zone at the Hanford Site. Some of the contaminants currently reside in the deeper parts of the vadose zone where they are much less accessible to characterization, monitoring, and typical remediation activities. The DOE Richland Operations Office (DOE-RL) prepared a treatability test plan in 2008 to examine remediation options for addressing contaminants in the deep vadose zone; one of the technologies identified was surface barriers (also known as engineered barriers, covers, and caps). In the typical configuration, the contaminants are located relatively close to the surface, generally within 15 m, and thus they are close to the base of the surface barrier. The proximity of the surface barrier under these conditions yielded few concerns about the effectiveness of the barrier at depth, particularly for cases in which the contaminants were in a lined facility. At Hanford, however, some unlined sites have contaminants located well below depths of 15 m. The issue raised about these sites is the degree of effectiveness of a surface barrier in isolating contaminants in the deep vadose zone. Previous studies by Hanford Site and PNNL researchers suggest that surface barriers have the potential to provide a significant degree of isolation of deep vadose zone contaminants. The studies show that the actual degree of isolation is site-specific and depends on many factors, including recharge rates, barrier size, depth of contaminants, geohydrologic properties ofthe sediments, and the geochemical interactions between the contaminants and the sediments. After the DOE-RL treatability test plan was published, Pacific Northwest National Laboratory was contracted to review the information available to support surface barrier evaluation for the deep vadose zone, identify gaps in the information and outcomes necessary to fill the data gaps, and outline tasks to achieve those outcomes. Full understanding of contaminant behavior in the deep vadose zone is constrained by four key data gaps: limited access; limited data; limited time; and the lack of an accepted predictive capability for determining whether surface barriers can effectively isolate deep vadose zone contaminants. Activities designed to fill these data gaps need to have these outcomes: (1) common evaluation methodology that provides a clear, consistent, and defensible basis for evaluating groundwater impacts caused by placement of a surface barrier above deep vadose zone contamination; (2) deep vadose zone data that characterize the lithology, the spatial distribution of moisture and contaminants, the physical, chemical, and biological process that affect the mobility of each contaminant, and the impacts to the contaminants following placement of a surface barrier; (3) subsurface monitoring to provide subsurface characterization of initial conditions and changes that occur during and following remediation activities; and (4) field observations that span years to decades to validate the evaluation methodology. A set of six proposed tasks was identified to provide information needed to address the above outcomes. The proposed tasks are: (1) Evaluation Methodology - Develop common evaluation methodology that will provide a clear, consistent, and defensible basis for evaluating groundwater impacts caused by placement of a surface barrier above deep vadose zone contamination. (2) Case Studies - Conduct case studies to demonstrate the applicability ofthe common evaluation methodology and provide templates for subsequent use elsewhere. Three sites expected to have conditions that would yield valuable information and experience pertinent to deep vadose zone contamination were chosen to cover a range of conditions. The sites are BC Cribs and Trenches, U Plant Cribs, and the T Farm Interim Cover. (3) Subsurface Monitoring Technologies - Evaluate minimally invasive geophysical approaches for delineating subsurface plumes and monitoring their migration in the deep

  19. Microbially driven fracture sealing for inhibiting contaminant transport at the field scale

    NASA Astrophysics Data System (ADS)

    McMillan, Lindsay; Cuthbert, Mark; Riley, Michael; Handley-Sidhu, Stephanie; Tobler, Dominique; Phoenix, Vernon

    2013-04-01

    Successful implementation of subsurface carbon storage and nuclear waste containment schemes relies on transmissivity reduction through the sealing of fractures in the surrounding rocks. Effective transmissivity reduction in fine scale features is difficult to achieve using traditional high viscosity cement grouts injected at high pressures. However, laboratory scale studies suggest microbially induced calcite precipitation (MICP) can provide a low-viscosity alternative. The first field trials of MICP in fractured hard rock were carried out in a multiple borehole array by using the ureolytic bacterium Sporosarcina pasteurii. Flow at depth at the experimental site is dominated by a single fracture. Injection of the bacteria in parallel with a 'cementing fluid' of urea and calcium chloride was used to fix the bacteria in the subsurface. Subsequent flushing with the cementing fluid alone drove further ureolysis and calcite precipitation. Calcite precipitation is eventually limited by crystal growth preventing interaction of the accumulated bacteria with the cementing fluid; repeated bacteria injections are necessary. Coupled equations for bacterial and urea transport, bacterial accumulation, and calcite production were used to model the field trial numerically and gave excellent agreement with field data. While a significant reduction in the transmissivity of the fracture was achieved over several m2 the modelling results suggest challenges remain in encouraging aperture reduction at a distance from the injection borehole due primarily to cementation and clogging around the bacteria injection hole. A further borehole array at the same site provides the opportunity for additional experiments informed by the promising initial results. Models of a number of alternative bacteria and cementing fluid injection schemes have been created using the geometry of the new borehole array. These models have been parameterised using the calibrated model from the initial field trial. Scenario testing suggests that using separate boreholes for bacteria injection and the subsequent cementing fluid flush can help prevent injection hole clogging. Flushing the injection hole with fresh water during the cementing stage may also help to reduce clogging by acting as a hydraulic barrier to the cementing fluid. While scenario testing has provided some alternative strategies, uncertainty surrounds particularly the relationship between urea concentration and bacterial accumulation and the rate limiting effect of calcite crystal growth. Short duration field trials are planned to reduce this uncertainty and improve the injection scheme design for a subsequent full-scale field trial. The lessons learned from these short trials will also be presented.

  20. Microbial activity in surface sediments of Chacopata-Bocaripo lagoon axis, Sucre State, Venezuela.

    PubMed

    Segnini de B, Mary Isabel; Gómez, Irma; Brito, Leonor; Acosta, Vanessa; Troccoli, Luis

    2015-02-28

    The aim of this work was to evaluate the microbial activity of the surface sediments (0-10cm) of the Chacopata-Bocaripo lagoon axis (Ch-BLA) through microbiological parameters: microbial biomass (Cmic) dehydrogenase activity (DHS), fluorescein diacetate hydrolysis (HFDA), arginine ammonification (AA) and biochemical parameters: phosphatase (PHa) and urease (URa) activity. They were determined during transition (July 2010) and upwelling (March 2011) periods. Total organic carbon (TOC) did not vary significantly (p?0.05) between climatic periods. All the parameters studied were higher in upwelling season: Cmic (191.79mgCmickg(-1)), DHS (228.70?gTFFg(-1)24h(-1)), HFDA (204.09?g fluoresceing(-1)24h(-1)), AA (13.09?gNH4-Ng(-1)h(-1)), PHa (132.31?g pNFg(-1)h(-1)), URa (12.90?gNH4-Ng(-1)h(-1)). They appear to be controlled by the availability and quality of nutrients in each climatic period, and were useful tools for evaluating changes in microbial activity in marine sediments. PMID:25455789

  1. Assessment of Microbial Contaminants Present on Vacuum Loaders in Shell Egg Processing Facilities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous studies have shown vacuum loader cups in shell egg processing facilities to be a reservoir of high levels of bacteria. This study was conducted to determine the prevalence of pathogens on the surface of the vacuum loaders cups. An off-line and a mixed operation shell egg processing facili...

  2. Removal of Microbial Contaminants in Drinking Water: Siemens Corporation Memcor® S10V Ultrafiltration Module

    EPA Science Inventory

    The Siemens Memcor S10V UF module was tested for removal of endospores of the bacteria Bacillus atrophaeus and the MS2 coliphage virus according to the requirements of the EPA Long-Term 2 Enchanced Surface Water Treatment Rule (LT2ESWTR). B. atrophaeus served as a surrogate for ...

  3. Removal of Microbial Contaminants in Drinking Water: Siemens Corporation Memcor® L20V Ultrafiltration Module

    EPA Science Inventory

    The Siemens Memcor L20V UF module was tested for removal of endospores of the bacteria Bacillus atrophaeus and the MS2 coliphage virus according to the requirements of the EPA Long-Term 2 Enchanced Surface Water Treatment Rule (LT2ESWTR). B. atrophaeus served as a surrogate for ...

  4. Removal of Microbial Contaminants in Drinking Water: Siemens Corporation Memcor® L10V Ultrafiltration Module

    EPA Science Inventory

    The Siemens Memcor L10V UF module was tested for removal of Cryptosporidium parvum oocyste, endospores of the bacteria Bacillus atrophaeus, and the MS2 coliphage virus according to the requirements of the EPA Long-Term 2 Enchanced Surface Water Treatment Rule (LT2ESWTR). Five m...

  5. Active cleaning technique for removing contamination from optical surfaces in space

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.; Cruz, G. A.

    1973-01-01

    An active cleaning technique for removing contaminants from optical surfaces in space was investigated with emphasis on the feasibility of using plasma exposure as a means of in-situ cleaning. The major work accomplished includes: (1) development of an in-situ reflectometer for use in conjunction with the contaminant film deposition/cleaning facility; (2) completion of Apollo Telescope Mount (ATM) filter treatment experiments to assess the effects of plasma exposure on the UV transmittance; (3) attempts to correlate the atomic oxygen flux with cleaning rate; (4) completion of in-situ butadien contamination/plasma cleaning/UV reflectance measurement experiments; (5) carbon cleaning experiments using various gases; (6) completion of silicone contamination/cleaning experiments; and (7) experiments conducted at low chamber pressures to determine cleaning rate distribution and contamination of surfaces adjacent to those being cleaned.

  6. Bioremediation of diesel oil in a co-contaminated soil by bioaugmentation with a microbial formula tailored with native strains selected for heavy metals resistance.

    PubMed

    Alisi, Chiara; Musella, Rosario; Tasso, Flavia; Ubaldi, Carla; Manzo, Sonia; Cremisini, Carlo; Sprocati, Anna Rosa

    2009-04-01

    The aim of the work is to assess the feasibility of bioremediation of a soil, containing heavy metals and spiked with diesel oil (DO), through a bioaugmentation strategy based on the use of a microbial formula tailored with selected native strains. The soil originated from the metallurgic area of Bagnoli (Naples, Italy). The formula, named ENEA-LAM, combines ten bacterial strains selected for multiple resistance to heavy metals among the native microbial community. The biodegradation process of diesel oil was assessed in biometer flasks by monitoring the following parameters: DO composition by GC-MS, CO2 evolution rate, microbial load and composition of the community by T-RFLP, physiological profile in Biolog ECOplates and ecotoxicity of the system. The application of this microbial formula allowed to obtain, in the presence of heavy metals, the complete degradation of n-C(12-20), the total disappearance of phenantrene, a 60% reduction of isoprenoids and an overall reduction of about 75% of the total diesel hydrocarbons in 42 days. Concurrently with the increase of metabolic activity at community level and the microbial load, the gradual abatement of the ecotoxicity was observed. The T-RFLP analysis highlighted that most of the ENEA-LAM strains survived and some minor native strains, undetectable in the soil at the beginning of the experiment, developed. Such a bioaugmentation approach allows the newly established microbial community to strike a balance between the introduced and the naturally present microorganisms. The results indicate that the use of a tailored microbial formula may efficiently facilitate and speed up the bioremediation of matrices co-contaminated with hydrocarbons and heavy metals. The study represents the first step for the scale up of the system and should be verified at a larger scale. In this view, this bioaugmentation strategy may contribute to overcome a critical bottleneck of the bioremediation technology. PMID:19201450

  7. Microbial biosafety of pilot-scale bioreactor treating MTBE and TBA-contaminated drinking water supply

    PubMed Central

    Schmidt, Radomir; Klemme, David A.; Scow, Kate; Hristova, Krassimira

    2012-01-01

    A pilot-scale sand-based fluidized bed bioreactor (FBBR) was utilized to treat both methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) from a contaminated aquifer. To evaluate the potential for re-use of the treated water, we tested for a panel of water quality indicator microorganisms and potential waterborne pathogens including total coliforms, E. coli, Salmonella and Shigella spp., Campylobacter jejuni, Aeromonas hydrophila, Legionella pneumophila, Vibrio cholerae, Yersinia enterocolytica and Mycobacterium avium in both influent and treated waters from the bioreactor. Total bacteria decreased during FBBR treatment. E. coli, Salmonella and Shigella spp., C. jejuni, V. cholerae, Y. enterocolytica and M. avium were not detected in aquifer water or bioreactor treated water samples. For those pathogens detected, including total coliforms, L. pneumophila and A. hydrophila, numbers were usually lower in treated water than influent samples, suggesting removal during treatment. The detection of particular bacterial species reflected their presence or absence in the influent waters. PMID:22321859

  8. [Bioremediation of chromium (VI) contaminated site by reduction and microbial stabilization of chromium].

    PubMed

    Zheng, Jia-Chuan; Zhang, Jian-Rong; Liu, Xi-Wen; Xu, Qian; Shi, Wei-Lin

    2014-10-01

    Chromium (VI) contaminated soil samples were collected from a chemical plant in Suzhou. Firstly, the reduced soil was prepared by adding reagent (Stone-sulfure reagent) into polluted soil to transfer most chromium (VI) into chromium (III), then a nutrient solution was introduced into the reduced soil, and the stabilized soil was obtained after 60 days culturing. The chromium (VI) content of the three kinds of soil was analyzed. The results showed that the chromium (VI) content in toxicity characteristic leaching liquid (TCLL) dropped by 96. 8% (from 8.26 mg · L(-1) to 0.26 mg · L(-1)), and the total chromium content dropped by 95.7% (from 14.66 mg · L(-1) to 0.63 mg · L(-1)) after bioremediation in 5% nutrient solution. Additionally, the durability of chromium stabilization was tested by potassium permanganate oxidation and sterilization of microbe-treated soil. After oxidation, the chromium (VI) content in TCLL of the reduced soil was increased from 8.26 mg · L(-1) to 14.68 mg · L(-1). However, the content after bioremediation was decreased to 2.68 mg · L(-1). The results of sterilization demonstrated that the death of microbe had no significant effect on the stabilization of chromium. Consequently, the research in this paper demonstrated the feasibility of bioremediation of chromium (VI) polluted soil through reduction followed by stabilization/soilidification, and provided a technique with low cost but high efficiency. PMID:25693397

  9. Microbial Diversity Aboard Spacecraft: Evaluation of the International Space Station

    NASA Technical Reports Server (NTRS)

    Castro, Victoria A.; Thrasher, Adrianna N.; Healy, Mimi; Ott, C. Mark; Pierson, Duane L.

    2003-01-01

    An evaluation of the microbial flora from air, water, and surface samples provided a baseline of microbial diversity onboard the International Space Station (ISS) to gain insight into bacterial and fungal contamination during the initial stages of construction and habitation. Using 16S genetic sequencing and rep-PeR, 63 bacterial strains were isolated for identification and fingerprinted for microbial tracking. The use of these molecular tools allowed for the identification of bacteria not previously identified using automated biochemical analysis and provided a clear indication of the source of several ISS contaminants. Fungal and bacterial data acquired during monitoring do not suggest there is a current microbial hazard to the spacecraft, nor does any trend indicate a potential health risk. Previous spacecraft environmental analysis indicated that microbial contamination will increase with time and require continued surveillance.

  10. Microbial respiration and natural attenuation of benzene contaminated soils investigated by cavity enhanced Raman multi-gas spectroscopy.

    PubMed

    Jochum, Tobias; Michalzik, Beate; Bachmann, Anne; Popp, Jürgen; Frosch, Torsten

    2015-05-01

    Soil and groundwater contamination with benzene can cause serious environmental damage. However, many soil microorganisms are capable to adapt and are known to strongly control the fate of organic contamination. Innovative cavity enhanced Raman multi-gas spectroscopy (CERS) was applied to investigate the short-term response of the soil micro-flora to sudden surface contamination with benzene regarding the temporal variations of gas products and their exchange rates with the adjacent atmosphere. (13)C-labeled benzene was spiked on a silty-loamy soil column in order to track and separate the changes in heterotrophic soil respiration - involving (12)CO2 and O2- from the natural attenuation process of benzene degradation to ultimately form (13)CO2. The respiratory quotient (RQ) decreased from a value 0.98 to 0.46 directly after the spiking and increased again within 33 hours to a value of 0.72. This coincided with the maximum (13)CO2 concentration rate (0.63 ?mol m(-2) s(-1)), indicating the highest benzene degradation at 33 hours after the spiking event. The diffusion of benzene in the headspace and the biodegradation into (13)CO2 were simultaneously monitored and 12 days after the benzene spiking no measurable degradation was detected anymore. The RQ finally returned to a value of 0.96 demonstrating the reestablished aerobic respiration. PMID:25751376

  11. Combined Contamination and Space Environmental Effects on Solar Cells and Thermal Control Surfaces

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Bruckner, Eric J.; Scheiman, David A.; Stidham, Curtis R.

    1994-01-01

    For spacecraft in low Earth orbit (LEO), contamination can occur from thruster fuel, sputter contamination products and from products of silicone degradation. This paper describes laboratory testing in which solar cell materials and thermal control surfaces were exposed to simulated spacecraft environmental effects including contamination, atomic oxygen, ultraviolet radiation and thermal cycling. The objective of these experiments was to determine how the interaction of the natural LEO environmental effects with contaminated spacecraft surfaces impacts the performance of these materials. Optical properties of samples were measured and solar cell performance data was obtained. In general, exposure to contamination by thruster fuel resulted in degradation of solar absorptance for fused silica and various thermal control surfaces and degradation of solar cell performance. Fused silica samples which were subsequently exposed to an atomic oxygen/vacuum ultraviolet radiation environment showed reversal of this degradation. These results imply that solar cells and thermal control surfaces which are susceptible to thruster fuel contamination and which also receive atomic oxygen exposure may not undergo significant performance degradation. Materials which were exposed to only vacuum ultraviolet radiation subsequent to contamination showed slight additional degradation in solar absorptance.

  12. Microbial Air and Surface Monitoring Results from International Space Station Samples

    NASA Technical Reports Server (NTRS)

    Ott, C. Mark; Bruce, Rebekah J.; Castro, Victoria A.; Novikova, Natalia D.; Pierson, D. L.

    2005-01-01

    Over the course of long-duration spaceflight, spacecraft develop a microbial ecology that directly interacts with the crew of the vehicle. While most microorganisms are harmless or beneficial to the inhabitants of the vehicle, the presence of medically significant organisms appearing in this semi-closed environment could adversely affect crew health and performance. The risk of exposure of the crew to medically significant organisms during a mission is estimated using information gathered during nominal and contingency environmental monitoring. Analysis of the air and surface microbiota in the habitable compartments of the International Space Station (ISS) over the last four years indicate a high presence of Staphylococcus species reflecting the human inhabitants of the vehicle. Generally, air and surface microbial concentrations are below system design specifications, suggesting a lower risk of contact infection or biodegradation. An evaluation of sample frequency indicates a decrease in the identification of new species, suggesting a lower potential for unknown microorganisms to be identified. However, the opportunistic pathogen, Staphylococcus aureus, has been identified in 3 of the last 5 air samples and 5 of the last 9 surface samples. In addition, 47% of the coagulase negative Staphylococcus species that were isolated from the crew, ISS, and its hardware were found to be methicillin resistance. In combination, these observations suggest the potential of methicillin resistant infectious agents over time.

  13. Persistence of Microbial Contamination on Transvaginal Ultrasound Probes despite Low-Level Disinfection Procedure

    PubMed Central

    M'Zali, Fatima; Bounizra, Carole; Leroy, Sandrine; Mekki, Yahia; Quentin-Noury, Claudine; Kann, Michael

    2014-01-01

    Aim of the Study In many countries, Low Level Disinfection (LLD) of covered transvaginal ultrasound probes is recommended between patients' examinations. The aim of this study was to evaluate the antimicrobial efficacy of LLD under routine conditions on a range of microorganisms. Materials and Methods Samples were taken over a six month period in a private French Radiology Center. 300 specimens derived from endovaginal ultrasound probes were analyzed after disinfection of the probe with wipes impregnated with a quaternary ammonium compound and chlorhexidine. Human papillomavirus (HPV) was sought in the first set of s100 samples, Chlamydia trachomatis and mycoplasmas were searched in the second set of 100 samples, bacteria and fungi in the third 100 set samples. HPV, C. trachomatis and mycoplasmas were detected by PCR amplification. PCR positive samples were subjected to a nuclease treatment before an additional PCR assay to assess the likely viable microorganisms. Bacteria and fungi were investigated by conventional methods. Results A substantial persistence of microorganisms was observed on the disinfected probes: HPV DNA was found on 13% of the samples and 7% in nuclease-resistant form. C. trachomatis DNA was detected on 20% of the probes by primary PCR but only 2% after nuclease treatment, while mycoplasma DNA was amplified in 8% and 4%, respectively. Commensal and/or environmental bacterial flora was present on 86% of the probes, occasionally in mixed culture, and at various levels (10->3000 CFU/probe); Staphylococcus aureus was cultured from 4% of the probes (10-560 CFU/probe). No fungi were isolated. Conclusion Our findings raise concerns about the efficacy of impregnated towels as a sole mean for disinfection of ultrasound probes. Although the ultrasound probes are used with disposable covers, our results highlight the potential risk of cross contamination between patients during ultrasound examination and emphasize the need for reviewing the disinfection procedure. PMID:24695371

  14. Microbial production, enzyme activity, and carbon turnover in surface sediments of the Hudson River estuary.

    PubMed

    Sinsabaugh, R L; Findlay, S

    1995-09-01

    The detrital food web is a major nexus of energy flow in nearly all aquatic ecosystems. Energy enters this nexus by microbial assimilation of detrital carbon. To link microbiological variables with ecosystem process, it is necessary to understand the regulatory hierarchy that controls the distribution of microbial biomass and activity. Toward that goal, we investigated variability in microbial abundance and activities within the tidal freshwater estuary of the Hudson River. Surface sediments were collected from four contrasting sites: a mid-channel shoal, two types of wetlands, and a tributary confluence. These samples, collected in June to August 1992, were sorted into two to four size fractions, depending on the particle size distribution at each site. Each fraction was analyzed for bacterial biomass (by acridine orange direct counting), bacterial production (by (3)H-thymidine incorporation into DNA), fungal biomass (by ergosterol extraction), fungal production (by biomass accrual), and the potential activities of seven extracellular enzymes involved in the degradation of detrital structural molecules. Decomposition rates for particulate organic carbon (POC) were estimated from a statistical model relating mass loss rates to endocellulase activity. Within samples, bacterial biomass and productivity were negatively correlated with particle size: Standing stocks and rates in the <63-?m class were roughly twofold greater than in the >4-mm class. Conversely, fungal biomass was positively correlated with particle size, with standing stocks in the largest size class more than 1OX greater than in the smallest. Extracellular enzyme activities also differed significantly among size classes, with high carbohydrase activities associated with the largest particles, while oxidative activities predominated in the smallest size classes. Among sites, the mid-channel sediments had the lowest POC standing stock (2% of sediment dry mass) and longest turnover time (approximately 1.7 years), with bacterial productivity approximately equal to fungal (56 vs. 46 ?g C per gram POC per day, respectively). In the Typha wetland, POC standing stock was high (10%); turnover time was about 0.3 years; and 90% of the microbial productivity was fungal (670 vs. 84 ?g C per gram POC per day). The other two sites, a Trapa wetland and a tributary confluence, showed intermediate values for microbial productivity and POC turnover. Differences among sites were described by regression models that related the distribution of microbial biomass (r (2) = 0.98) and productivity (r (2) = 0.81) to particle size and carbon quality. These factors also determined POC decomposition rates. Net microbial production efficiency (production rate/decomposition rate) averaged 10.6%, suggesting that the sediments were exporting large quantities of unassimilated dissolved organic carbon into the water column. Our results suggest that studies of carbon processing in large systems, like the Hudson River estuary, can be facilitated by regression models that relate microbial dynamics to more readily measured parameters. PMID:24185480

  15. Prevention: A New and Maybe Wiser Approach to the Surface Contamination Issues

    SciTech Connect

    Rouppert, F.; Santarella, I.; Ackermann, E.; Tiquet, P.; Secourgeon, L.

    2003-02-26

    A decrease in the efficiency of some decontamination processes may occur after several implementations on the same surface, as recontamination between each implementation can occur. In some situations, achieving decontamination to acceptable levels can become difficult. The origin of this problem has been highlighted and solutions have been found. In fact, by thoroughly cleaning the surface, the decontamination process may lead to an increase of the adhesion of subsequent contaminants, thus making them much more difficult to remove. In concrete terms, some chemical functional groups, such as hydroxides make possible the chemical sorption of metal ions. Simply removing grease or natural pollutants from the surface allows direct contact between the contaminants and these reactive sites, increasing adhesion. If the cleaning process is badly suited to the material to be decontaminated, a modification of the chemical composition of the surface can occur, possibly increasing the density of reactive sites, making the problem worse. Predicting the evolution of the surface chemical properties with time is a challenge. Prevention of surface contamination appears to be a wiser approach. The principle is to prevent strong adhesion of the contaminants by masking the reactive groups likely to chemically bind the contaminants to the surface. With this aim in view, different methods of surface treatments offering such barrier effects have been developed at the French atomic Energy Commission (CEA). One possibility is the use of a removable protective polymer film, which can be used also for decontamination purposes. The other possibility is the vapor phase deposition of inert mineral layers on the surface. In this paper, we will describe both the studies and results that lead us to this prevention approach to the surface contamination problem, and the improvements obtained in terms of decontamination efficiency with this new approach.

  16. Microbial monitoring of spacecraft and associated environments

    NASA Technical Reports Server (NTRS)

    La Duc, M. T.; Kern, R.; Venkateswaran, K.

    2004-01-01

    Rapid microbial monitoring technologies are invaluable in assessing contamination of spacecraft and associated environments. Universal and widespread elements of microbial structure and chemistry are logical targets for assessing microbial burden. Several biomarkers such as ATP, LPS, and DNA (ribosomal or spore-specific), were targeted to quantify either total bioburden or specific types of microbial contamination. The findings of these assays were compared with conventional, culture-dependent methods. This review evaluates the applicability and efficacy of some of these methods in monitoring the microbial burden of spacecraft and associated environments. Samples were collected from the surfaces of spacecraft, from surfaces of assembly facilities, and from drinking water reservoirs aboard the International Space Station (ISS). Culture-dependent techniques found species of Bacillus to be dominant on these surfaces. In contrast, rapid, culture-independent techniques revealed the presence of many Gram-positive and Gram-negative microorganisms, as well as actinomycetes and fungi. These included both cultivable and noncultivable microbes, findings further confirmed by DNA-based microbial detection techniques. Although the ISS drinking water was devoid of cultivable microbes, molecular-based techniques retrieved DNA sequences of numerous opportunistic pathogens. Each of the methods tested in this study has its advantages, and by coupling two or more of these techniques even more reliable information as to microbial burden is rapidly obtained. Copyright 2004 Springer-Verlag.

  17. LONG-TERM RECOVERY OF PCB-CONTAMINATED SURFACE SEDIMENTS AT THE SANGAMO-WESTON/TWELVEMILE CREEK/LAKE HARTWELL SUPERFUND SITE

    EPA Science Inventory

    Natural recovery of contaminated sediments relies on burial of contaminated sediments with increasingly clean sediments over time (i.e., natural capping). Natural capping reduces the risk of resuspension of contaminated surface sediments, and it reduces the potential for contamin...

  18. Mineralogical controls on surface colonization by sulfur-metabolizing microbial communities

    NASA Astrophysics Data System (ADS)

    Jones, A. A.; Bennett, P.

    2012-12-01

    When characterizing microbial diversity and the microbial ecosystem of the shallow subsurface the mineral matrix is generally assumed to be homogenous and unreactive. We report here experimental evidence that microorganisms colonize rock surfaces according to the rock's chemistry and the organism's metabolic requirements and tolerances. We investigated this phenomenon using laboratory biofilm reactors with both a pure culture of sulfur-oxidizing Thiothrix unzii and a mixed environmental sulfur-metabolizing community from Lower Kane, Cave, WY, USA. Reactors contained rock and mineral chips (calcite, albite, microcline, quartz, chert, Madison Limestone (ML), Madison Dolostone (MD), and basalt) amended with one of the two inoculants. Biomass of attached microorganisms on each mineral surface was quantified. The 16S rRNA of attached microbial communities were compared using Roche FLX and Titanium 454 next generation pyrosequencing. A primary controlling factor on taxonomy of attached microorganisms in both pure and mixed culture experiments was mineral buffering capacity. In mixed culture experiments acid-buffering carbonates were preferentially colonized by neutrophilic sulfur-oxidizing microorganisms (~18% to ~27% of microorganisms), while acidophilic sulfur-oxidizing microorganisms colonized non-buffering quartz exclusively (~46% of microorganisms). The nutrient content of the rock was a controlling factor on biomass accumulation, with neutrophilic organisms selecting between carbonate surfaces of equivalent buffer capacities according to the availability of phosphate. Dry biomass on ML was 17.8 ± 2.3 mg/cm2 and MD was 20.6 ± 6.8 mg/cm2; while nutrient poor calcite accumulated 2.4 ± 0.3 mg/cm2. Biomass accumulation was minimal on non-buffering nutrient-limited surfaces. These factors are countered by the competitive exclusion of some populations. A pure culture of T. unzii preferentially colonizes carbonates while a very closely related Thiothrix spp is excluded from these same rock samples in a mixed culture. Diversity analysis reveals that ML, MD, and calcite have >98% of sequences belonging to shared OTUs. The carbonates have <3% of sequences belonging to OTUs shared with any silicate mineral surface with the exception of basalt (~85% similarity). These four surfaces were host to the least diverse microbial communities, suggesting that competitive exclusion of microorganisms not adapted to these surfaces is a controlling variable on taxonomy. Furthermore, the microorganisms on basalt reveal an unique association between Thiothrix unzii (often found in mid-ocean ridge environments) and basalt, where it excludes other sulfur oxidizers and accumulates the highest non-carbonate biomass in both pure (3.5 ± 1.0 mg/cm2) and mixed culture (5.4 ± 1.4 mg/cm2) experiments. This association suggests that adaptations to specific rocks may be retained even when the organism is displaced from an ancestral rock/mineral surface habitat. Combined, these variables (buffering capacity, nutrient availability, competitive exclusion, tolerance of surface geochemistry, and latent adaptations) affect biomass density, local diversity, and global diversity of the attached communities on mineral and rock surfaces and suggest that different populations are more tolerant of, and more competitive on, specific rock/mineral types.

  19. Final Report: Molecular Basis for Microbial Adhesion and Geochemical Surface Reactions: A Study Across Scales

    SciTech Connect

    Dixon, David Adams [The University of Alabama

    2013-06-27

    Computational chemistry was used to help provide a molecular level description of the interactions of Gram-negative microbial membranes with subsurface materials. The goal is to develop a better understanding of the molecular processes involved in microbial metal binding, microbial attachment to mineral surfaces, and, eventually, oxidation/reduction reactions (electron transfer) that can occur at these surfaces and are mediated by the bacterial exterior surface. The project focused on the interaction of the outer microbial membrane, which is dominated by an exterior lipopolysaccharide (LPS) portion, of Pseudomonas aeruginosa with the mineral goethite and with solvated ions in the environment. This was originally a collaborative project with T.P. Straatsma and B. Lowery of the Pacific Northwest National Laboratory. The University of Alabama effort used electronic structure calculations to predict the molecular behavior of ions in solution and the behavior of the sugars which form a critical part of the LPS. The interactions of the sugars with metal ions are expected to dominate much of the microscopic structure and transport phenomena in the LPS. This work, in combination with the molecular dynamics simulations of Straatsma and the experimental electrochemistry and microscopy measurements of Lowry, both at PNNL, is providing new insights into the detailed molecular behavior of these membranes in geochemical environments. The effort at The University of Alabama has three components: solvation energies and structures of ions in solution, prediction of the acidity of the critical groups in the sugars in the LPS, and binding of metal ions to the sugar anions. An important aspect of the structure of the LPS membrane as well as ion transport in the LPS is the ability of the sugar side groups such as the carboxylic acids and the phosphates to bind positively charged ions. We are studying the acidity of the acidic side groups in order to better understand the ability of these groups to bind metal ions. We need to understand the solvation properties of the metal ions in solution and their ability to bind not only to the sugars but to proteins and to other anions. Our goal is then to be able to predict the ability of the side groups to bind metal ions. One result from the earlier molecular dynamics simulations is the exclusion of water from the inner hydrophobic part of the membrane. We thus need to investigate the binding of the cations in media with different dielectric constants.

  20. Evidence of the Generation of Isosaccharinic Acids and Their Subsequent Degradation by Local Microbial Consortia within Hyper-Alkaline Contaminated Soils, with Relevance to Intermediate Level Radioactive Waste Disposal.

    PubMed

    Rout, Simon P; Charles, Christopher J; Garratt, Eva J; Laws, Andrew P; Gunn, John; Humphreys, Paul N

    2015-01-01

    The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0) soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12. Soil and porewater profiles around the site indicated clear evidence of the presence of the ? and ? stereoisomers of isosaccharinic acid (ISA) resulting from the anoxic, alkaline degradation of cellulosic material. ISAs are of particular interest with regards to the disposal of cellulosic materials contained within the intermediate level waste (ILW) inventory of the United Kingdom, where they may influence radionuclide mobility via complexation events occurring within a geological disposal facility (GDF) concept. The mixing of uncontaminated soils with the alkaline leachate of the site resulted in ISA generation, where the rate of generation in-situ is likely to be dependent upon the prevailing temperature of the soil. Microbial consortia present in the uncontaminated soil were capable of surviving conditions imposed by the alkaline leachate and demonstrated the ability to utilise ISAs as a carbon source. Leachate-contaminated soil was sub-cultured in a cellulose degradation product driven microcosm operating at pH 11, the consortia present were capable of the degradation of ISAs and the generation of methane from the resultant H2/CO2 produced from fermentation processes. Following microbial community analysis, fermentation processes appear to be predominated by Clostridia from the genus Alkaliphilus sp, with methanogenesis being attributed to Methanobacterium and Methanomassiliicoccus sp. The study is the first to identify the generation of ISA within an anthropogenic environment and advocates the notion that microbial activity within an ILW-GDF is likely to influence the impact of ISAs upon radionuclide migration. PMID:25748643

  1. Evidence of the Generation of Isosaccharinic Acids and Their Subsequent Degradation by Local Microbial Consortia within Hyper-Alkaline Contaminated Soils, with Relevance to Intermediate Level Radioactive Waste Disposal

    PubMed Central

    Rout, Simon P.; Charles, Christopher J.; Garratt, Eva J.; Laws, Andrew P.; Gunn, John; Humphreys, Paul N.

    2015-01-01

    The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0) soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12. Soil and porewater profiles around the site indicated clear evidence of the presence of the ? and ? stereoisomers of isosaccharinic acid (ISA) resulting from the anoxic, alkaline degradation of cellulosic material. ISAs are of particular interest with regards to the disposal of cellulosic materials contained within the intermediate level waste (ILW) inventory of the United Kingdom, where they may influence radionuclide mobility via complexation events occurring within a geological disposal facility (GDF) concept. The mixing of uncontaminated soils with the alkaline leachate of the site resulted in ISA generation, where the rate of generation in-situ is likely to be dependent upon the prevailing temperature of the soil. Microbial consortia present in the uncontaminated soil were capable of surviving conditions imposed by the alkaline leachate and demonstrated the ability to utilise ISAs as a carbon source. Leachate-contaminated soil was sub-cultured in a cellulose degradation product driven microcosm operating at pH 11, the consortia present were capable of the degradation of ISAs and the generation of methane from the resultant H2/CO2 produced from fermentation processes. Following microbial community analysis, fermentation processes appear to be predominated by Clostridia from the genus Alkaliphilus sp, with methanogenesis being attributed to Methanobacterium and Methanomassiliicoccus sp. The study is the first to identify the generation of ISA within an anthropogenic environment and advocates the notion that microbial activity within an ILW-GDF is likely to influence the impact of ISAs upon radionuclide migration. PMID:25748643

  2. Bacterial Contamination of Hands Increases Risk of Cross-Contamination among Low-Income Puerto Rican Meal Preparers

    ERIC Educational Resources Information Center

    Dharod, Jigna Morarji; Paciello, Stefania; Bermudez-Millan, Angela; Venkitanarayanan, Kumar; Damio, Grace; Perez-Escamilla, Rafael

    2009-01-01

    Objective: To examine the association of microbial contamination of the meal preparer's hands with microbial status of food and kitchen/utensil surfaces during home preparation of a "Chicken and Salad" meal. Design and Setting: Observational home food safety assessment. Before starting meal preparation, participants' hands were tested to estimate…

  3. Characterization and phylogenetic analysis of microbial surface active compound-producing bacteria.

    PubMed

    Saimmai, Atipan; Rukadee, Onkamon; Onlamool, Theerawat; Sobhon, Vorasan; Maneerat, Suppasil

    2012-11-01

    Microbial surface active compounds (SACs) were isolated from various environmental sources in Thailand. Isolates were screened for SACs production in different carbon sources (crude glycerol, commercial sugar, decanter, glucose, molasses, used palm oil, and used lubricating oil) by using drop-collapsing test and emulsification activity. Molasses produced the highest number of positive results (23 of 25 isolates). Twenty-one isolate strains produced emulsions with xylene, and 15 exhibited high emulsion-stabilizing capacity, maintaining more than 50 % of the original emulsion volume for 24 h, and six isolate strains reduced the growth medium surface tension to 40 mN/m. The phylogenetic position of these 25 isolates was evaluated by 16S rRNA gene sequence analysis. The production of microbial SACs was determined for strains representative of 16 different bacterial genera, in which ten genera (Blastococcus, Erysipelothrix, Humicoccus, Methylophilus, Microlunatus, Nevskia, Pectinatus, Rubrimonas, Selenomonas, and Stenotrophomonas) were firstly reported as SAC-producing strains. Overall, the new SAC-producing strains isolated in this study display promising features for the future development and use in economically efficient industrial-scale biotechnological processes. PMID:22899015

  4. Geohydrology and susceptibility of major aquifers to surface contamination in Alabama, area 7

    USGS Publications Warehouse

    Mooty, W.S.

    1987-01-01

    The geohydrology and susceptibility of the seven major aquifers to surface contamination in Area 7 - Bibb, Dallas, Hale, Perry, and Wilcox Counties, are described. Aquifers in the northern part of the study area are in Paleozoic limestones and dolomite formations. Deposits in the central part of the study area are predominately of Cretaceous age and contain the Coker, Gordo, and Eutaw aquifers. Although the southern part of the study area has many deposits of Tertiary age, the Ripley Formation of Cretaceous age is the major aquifer. Contamination of any of the major aquifers is improbable because the majority of the recharge area for the primary aquifers is woodland, pasture, or farmland. Downdip from their outcrops, the major aquifers in the study area are protected from land surface contamination by relatively impermeable layers of clay and chalk. The aquifers that are highly susceptible to contamination are the ones in the limestone and dolomite formations in northern Bibb County. Sinkholes exist in the recharge area of these formations and could provide a direct link for contaminates from the land surface to the water table. An area northeast of the Selma well field is also highly susceptible to contamination. The Eutaw Formation in this area is overlain by alluvial deposits that could increase recharge to the aquifer by slowing the runoff rate of surface water. (USGS)

  5. ANNUAL REPORT. ATMOSPHERIC-PRESSURE PLASMA CLEANING OF CONTAMINATED SURFACES

    EPA Science Inventory

    The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of nuclear waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly unde...

  6. Low-energy beta spectroscopy using pin diodes to monitor tritium surface contamination

    SciTech Connect

    Wampler, W.R.; Doyle, B.L.

    1994-06-01

    We show that tritium betas emitted from a surface can be counted using a pin photodiode as a solid state charged particle detector. Furthermore, we show that the range of tritium betas through air is sufficient to allow measurement of tritium on samples in air by this method. These two findings make possible a new method to survey tritium surface contamination which has advantages over existing methods. We have built and tested several prototype instruments which use this method to measure tritium surface contamination, including a compact portable unit. The design of these instruments and results from tests and calibrations are described. Potential applications of this new method to monitor tritium are discussed.

  7. Filtering the surface EMG signal: Movement artifact and baseline noise contamination

    E-print Network

    De Luca, Carlo J.

    Filtering the surface EMG signal: Movement artifact and baseline noise contamination Carlo J. De Article history: Accepted 5 January 2010 Keywords: EMG signal Movement artifact Baseline noise Filtering a b s t r a c t The surface electromyographic (sEMG) signal that originates in the muscle

  8. Spectral reflectance and emissivity of man-made surfaces contaminated with environmental

    E-print Network

    Salvaggio, Carl

    Spectral reflectance and emissivity of man-made surfaces contaminated with environmental effects for several man-made surfaces asphalt, concrete, roofing shingles, and vehicles under varying amounts of sand-principles physics-based simulation model that uses computer-aided design CAD descriptions of natural and man-made ob

  9. Development of inspection techniques for quantitatively measuring surface contamination on SRM hardware

    NASA Technical Reports Server (NTRS)

    Law, R. D.

    1989-01-01

    A contaminant is any material or substance which is potentially undesirable or which may adversely affect any part, component, or assembly. Contamination control of SRM hardware surfaces is a serious concern, for both Thiokol and NASA, with particular concern for contaminants which may adversely affect bonding surfaces. The purpose of this study is to develop laboratory analytical techniques which will make it possible to certify the cleanliness of any designated surface, with special focus on particulates (dust, dirt, lint, etc.), oils (hydrocarbons, silicones, plasticizers, etc.), and greases (HD-2, fluorocarbon grease, etc.). The hardware surfaces of concern will include D6AC steel, aluminum alloys, anodized aluminum alloys, glass/phenolic, carbon/phenolic, NBR/asbestos-silica, and EPDM rubber.

  10. Contamination of surface-water bodies after reactor accidents by the erosion of atmospherically deposited radionuclides

    SciTech Connect

    Helton, J.C.; Muller, A.B.; Bayer, A.

    1985-06-01

    Reactor safety analyses usually do not consider the population risk which might result from the contamination of surface-water bodies after reactor accidents by the erosion of atmospherically deposited radionuclides. This paper is intended to provide perspective on the reasonableness of this omission. Data are presented which are suggestive of the rates at which atmospherically deposited radionuclides might erode into surface-water bodies. These rates are used in the calculation of potential health effects resulting from surface-water contamination due to such erosion. These health effects are compared with predicted health effects due to atmospheric and terrestrial pathways after reactor accidents. The presented results support the belief that the contamination of surface-water bodies after reactor accidents by the erosion of atmospherically deposited radionuclides is not a major contributor to the risk associated with such accidents.

  11. Was Mineral Surface Complexity and Toxicity an Impetus for Evolution of Microbial Extracellular Polymeric Substances?

    NASA Astrophysics Data System (ADS)

    Sahai, N.; Xu, J.; Zhu, C.; Campbell, J.; Hickey, W.; Zhang, N.

    2011-12-01

    Modern ecological niches are teeming with an astonishing diversity of microbial life closely associated with mineral surfaces, highlighting the remarkable success of microorganisms in conquering the challenges and capitalizing on the benefits presented by the mineral-water interface. Such community-living is enabled by an extracellular, polymeric, biofilm matrix developed at cell surfaces. Despite the energetic penalties, biofilm formation capability likely evolved on early Earth because of crucial cell survival functions, of which recognized roles include facilitating cell-attachment at mineral surfaces, intercellular signaling and lateral gene transfer, protection from dessication in tidal pools, and screening toxic UV light and toxic soluble metals. Cell-attachment to mineral surfaces was likely critical for cell survival and function, but the potential toxicity of mineral surfaces towards cells and the complexities of the mineral-water-cell interface in promoting biofilm formation, have not been fully appreciated. We examined the effects of nanoparticulate oxides (amorphous SiO2, anatase ?-TiO2, and ?-Al2O3) on EPS- and biofilm-producing wild-type strains and their isogenic knock-out mutants which are defective in EPS-producing ability. In detail, we used Gram-negative wild-type Pseudomonas aeruginosa PAO1 and its EPS knock-out mutant ?-psl, and the Gram-positive wild-type Bacillus subtilis NCIB3610 and its EPS-knock-out mutant yhxB?. We conducted bacterial growth experiments in the presence of each oxide in order to determine the viability of each cell type relative to oxide-free controls. The amount of EPS generated in the presence of oxides was also quantified and qualitatively analyzed by fluorescent stains. The results indicated a previously unrecognized role for microbial extracellular polymeric substances (EPS) in shielding both Gram-negative and Gram-positive cells against the toxic effects of mineral surfaces. This role is distinct from the protection provided against toxic soluble metals. Furthermore, we found that mineral toxicity is specific to the surface chemistry and particle size of the mineral, and that EPS protect against this mineral-specific toxicity via different mechanisms. Most intriguingly, we determined that EPS production is mineral-induced. By addressing the mechanistic detailed interactions at the mineral-water-cell interface, we provide insight to the potential impact of nanoparticulate mineral surfaces in promoting increased complexity of cell surfaces, including EPS and biofilm formation, on early Earth.

  12. Distribution of Chromium Contamination and Microbial Activity in Soil Aggregates Tetsu K. Tokunaga,* Jiamin Wan, Terry C. Hazen, Egbert Schwartz, Mary K. Firestone, Stephen R. Sutton,

    E-print Network

    Hazen, Terry

    within the surface tentials in soil aggregates that exhibit anaerobic interiors layer of aggregates microbial respiration. Sharply terminated Cr diffusion fronts develop experienced by redox-sensitive metal pri- rate­ and reaction rate­limited in anaerobic and aerobic aggregates, marily as stable solids

  13. Technical Basis for Evaluating Surface Barriers to Protect Groundwater from Deep Vadose Zone Contamination

    SciTech Connect

    Fayer, Michael J.; Ward, Anderson L.; Freedman, Vicky L.

    2010-02-03

    This document presents a strategy for evaluating the effectiveness of surface barriers for site-specific deep vadose zone remediation. The strategy provides a technically defensible approach to determine the depth to which a surface barrier can effectively isolate contaminants in the vadose at a specific site as a function of subsurface properties, contaminant distribution, barrier design, and infiltration control performance. The strategy also provides an assessment of additional data and information needs with respect to surface barrier performance for deep vadose zone applications. The strategy addresses the linkage between surface barriers and deep vadose zone in situ remediation activities, monitoring issues, and emerging science, technology, and regulatory objectives. In short, the report documents the existing knowledge base, identifies knowledge needs (based on data gaps), and suggests tasks whose outcomes will address those knowledge needs. More important, the report serves as a starting point to engage the regulator and stakeholder community on the viability of deploying surface barriers for deep vadose zone contamination. As that engagement unfolds, a systematic methodology can be formalized and instituted. The strategy is focused on deep vadose zone contamination and the methods needed to determine the impact to groundwater from those deep vadose zone contaminants. Processes that affect surface barrier performance, recharge in the areas surrounding the surface barrier, and the near-surface vadose zone beneath the barrier are acknowledged but are not addressed by this strategy. In addition, the collection of site-specific data on contaminant distribution and geologic structure and properties are programmatic responsibilities and are not provided by this strategy.

  14. Microbially mediated clinoptilolite regeneration in a multifunctional permeable reactive barrier used to remove ammonium from landfill leachate contamination: laboratory column evaluation.

    PubMed

    Nooten, Thomas Van; Diels, Ludo; Bastiaens, Leen

    2010-05-01

    This study focuses on multifunctional permeable reactive barrier (multibarrier) technology, combining microbial degradation and abiotic ion exchange processes for removal of ammonium from landfill leachate contamination. The sequential multibarrier concept relies on the use of a clinoptilolite-filled buffer compartment to ensure a robust ammonium removal in case of temporary insufficient microbial activities. An innovative strategy was developed to allow in situ clinoptilolite regeneration. Laboratory-scale clinoptilolite-filled columns were first saturated with ammonium, using real landfill leachate as well as synthetic leachates as feed media. Other inorganic metal cations, typically present in landfill leachate, had a detrimental influence on the ammonium removal capacity by competing for clinoptilolite exchange sites. On the other hand, the metals had a highly favorable impact on regeneration of the saturated material. Feeding the columns with leachate deprived from ammonium (e.g., by microbial nitrification in an upgradient compartment), resulted in a complete release of the previously sorbed ammonium from the clinoptilolite, due to exchange with metal cations present in the leachate. The released ammonium is then available for microbial consumption in a downgradient compartment. The regeneration process resulted in a slightly increased ammonium exchange capacity afterward. The described strategy throws a new light on sustainable use of sorption materials for in situ groundwater remediation, by avoiding the need for material replacement and the use of external chemical regenerants. PMID:20387879

  15. Surface Laplacian of scalp electrical signals and independent component analysis resolve EMG contamination of electroencephalogram.

    PubMed

    Fitzgibbon, S P; DeLosAngeles, D; Lewis, T W; Powers, D M W; Whitham, E M; Willoughby, J O; Pope, K J

    2014-10-16

    The serious impact of electromyogram (EMG) contamination of electroencephalogram (EEG) is well recognised. The objective of this research is to demonstrate that combining independent component analysis with the surface Laplacian can eliminate EMG contamination of the EEG, and to validate that this processing does not degrade expected neurogenic signals. The method involves sequential application of ICA, using a manual procedure to identify and discard EMG components, followed by the surface Laplacian. The extent of decontamination is quantified by comparing processed EEG with EMG-free data that was recorded during pharmacologically induced neuromuscular paralysis. The combination of the ICA procedure and the surface Laplacian, with a flexible spherical spline, results in a strong suppression of EMG contamination at all scalp sites and frequencies. Furthermore, the ICA and surface Laplacian procedure does not impair the detection of well-known, cerebral responses; alpha activity with eyes-closed; ERP components (N1, P2) in response to an auditory oddball task; and steady state responses to photic and auditory stimulation. Finally, more flexible spherical splines increase the suppression of EMG by the surface Laplacian. We postulate this is due to ICA enabling the removal of local muscle sources of EMG contamination and the Laplacian transform being insensitive to distant (postural) muscle EMG contamination. PMID:25455426

  16. Modeling of Transmittance Degradation Caused by Optical Surface Contamination by Atomic Oxygen Reaction with Adsorbed Silicones

    NASA Technical Reports Server (NTRS)

    Snyder, Aaron; Banks, Bruce; Miller, Sharon; Stueber, Thomas; Sechkar, Edward

    2001-01-01

    A numerical procedure is presented to calculate transmittance degradation caused by contaminant films on spacecraft surfaces produced through the interaction of orbital atomic oxygen (AO) with volatile silicones and hydrocarbons from spacecraft components. In the model, contaminant accretion is dependent on the adsorption of species, depletion reactions due to gas-surface collisions, desorption, and surface reactions between AO and silicone producing SiO(x), (where x is near 2). A detailed des