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1

Microbial activities and dissolved organic matter dynamics in oil-contaminated surface seawater from the Deepwater Horizon oil spill site.  

PubMed

The Deepwater Horizon oil spill triggered a complex cascade of microbial responses that reshaped the dynamics of heterotrophic carbon degradation and the turnover of dissolved organic carbon (DOC) in oil contaminated waters. Our results from 21-day laboratory incubations in rotating glass bottles (roller bottles) demonstrate that microbial dynamics and carbon flux in oil-contaminated surface water sampled near the spill site two weeks after the onset of the blowout were greatly affected by activities of microbes associated with macroscopic oil aggregates. Roller bottles with oil-amended water showed rapid formation of oil aggregates that were similar in size and appearance compared to oil aggregates observed in surface waters near the spill site. Oil aggregates that formed in roller bottles were densely colonized by heterotrophic bacteria, exhibiting high rates of enzymatic activity (lipase hydrolysis) indicative of oil degradation. Ambient waters surrounding aggregates also showed enhanced microbial activities not directly associated with primary oil-degradation (?-glucosidase; peptidase), as well as a twofold increase in DOC. Concurrent changes in fluorescence properties of colored dissolved organic matter (CDOM) suggest an increase in oil-derived, aromatic hydrocarbons in the DOC pool. Thus our data indicate that oil aggregates mediate, by two distinct mechanisms, the transfer of hydrocarbons to the deep sea: a microbially-derived flux of oil-derived DOC from sinking oil aggregates into the ambient water column, and rapid sedimentation of the oil aggregates themselves, serving as vehicles for oily particulate matter as well as oil aggregate-associated microbial communities. PMID:22509359

Ziervogel, Kai; McKay, Luke; Rhodes, Benjamin; Osburn, Christopher L; Dickson-Brown, Jennifer; Arnosti, Carol; Teske, Andreas

2012-01-01

2

Space hardware microbial contamination  

Microsoft Academic Search

Planetary Protection (PP) requirements imposed on unmanned planetary missions require that the spacecraft undergo rigorous bioload reduction prior to launch. The ability to quantitate bioburden on such spacecraft is dependent on developing new analytical methodologies that can be used to identify and trace biological contamination on flight hardware. The focus of new method development is to move forward and to

A. Baker; R. Kern; R. Mancinelli; K. Venkateswaren; N. Wainwright

2002-01-01

3

Microbial contamination of antiseptics and disinfectants  

Microsoft Academic Search

Background: There have been a number of reports on microbial contamination of antiseptics and disinfectants. At present, however, the necessity of measures to prevent contamination do not seem to be fully appreciated. We investigated microbial contamination of antiseptics and disinfectants that are used in our hospital.Methods: Fifty-one samples of benzaldonium chloride and chlorhexidine gluconate that were being used in the

Shigeharu Oie; Akira Kamiya

1996-01-01

4

Mathematical estimation of the level of microbial contamination on spacecraft surfaces by volumetric air sampling  

NASA Technical Reports Server (NTRS)

Microbiological sampling methods presently used for enumeration of microorganisms on spacecraft surfaces require contact with easily damaged components. Estimation of viable particles on surfaces using air sampling methods in conjunction with a mathematical model would be desirable. Parameters necessary for the mathematical model are the effect of angled surfaces on viable particle collection and the number of viable cells per viable particle. Deposition of viable particles on angled surfaces closely followed a cosine function, and the number of viable cells per viable particle was consistent with a Poisson distribution. Other parameters considered by the mathematical model included deposition rate and fractional removal per unit time. A close nonlinear correlation between volumetric air sampling and airborne fallout on surfaces was established with all fallout data points falling within the 95% confidence limits as determined by the mathematical model.

Oxborrow, G. S.; Roark, A. L.; Fields, N. D.; Puleo, J. R.

1974-01-01

5

Mathematical Estimation of the Level of Microbial Contamination on Spacecraft Surfaces by Volumetric Air Sampling  

PubMed Central

Microbiological sampling methods presently used for enumeration of microorganisms on spacecraft surfaces require contact with easily damaged components. Estimation of viable particles on surfaces using air sampling methods in conjunction with a mathematical model would be desirable. Parameters necessary for the mathematical model are the effect of angled surfaces on viable particle collection and the number of viable cells per viable particle. Deposition of viable particles on angled surfaces closely followed a cosine function, and the number of viable cells per viable particle was consistent with a Poisson distribution. Other parameters considered by the mathematical model included deposition rate and fractional removal per unit time. A close nonlinear correlation between volumetric air sampling and airborne fallout on surfaces was established with all fallout data points falling within the 95% confidence limits as determined by the mathematical model. PMID:4151118

Oxborrow, G. S.; Roark, A. L.; Fields, N. D.; Puleo, J. R.

1974-01-01

6

Airborne Microbial Contamination of Dental Units  

Microsoft Academic Search

Background: Occupational risk of dental personnel to microbial airborne contamination has been demonstrated through the increased prevalence of respiratory infections. The American Dental Association has suggested stringent protection for infectious agents present in dental aerosols. Materials and Methods: Occupational exposure of dentists to airborne microbial and mycological contamination in various locations of a dental school was monitored by sampling of

Mansour R. Azari; Ali Ghadjari; Mohammad Reza Massoudi Nejad; Negar Faghih Nasiree

7

Microbial processes and subsurface contaminants  

NASA Astrophysics Data System (ADS)

A Chapman Conference entitled “Microbial Processes in the Transport, Fate, and In Situ Treatment of Subsurface Contaminants” was held in Snowbird, Utah, October 1-3, 1986. Members of the program committee and session chairmen were Lenore Clesceri (Rensselaer Polytechnic Institute, Troy, N.Y.), David Gibson (University of Texas, Austin), James Mercer (GeoTrans, Inc., Herndon , Va.), Donald Michelsen (Virginia Polytechnic Institute and State University, Blacksburg), Fred Molz (Auburn University, Auburn, Ala.), Bruce Rittman (University of Illinois, Urbana), Gary Sayler (University of Tennessee, Knoxville), and John T. Wilson (U.S. Environmental Protection Agency, Ada, Okla.). The following report attempts to highlight the six sessions that constituted the conference. For additional information, including a bound summary and abstracts, contact Fred J. Molz, Civil Engineering Department, Auburn University, AL 36849 (telephone: 205-826-4321).

Molz, Fred J.

8

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

Microsoft Academic Search

BACKGROUND: The present study assessed microbial contamination in Italian dental surgeries. METHODS: An evaluation of water, air and surface microbial contamination in 102 dental units was carried out in eight Italian cities. RESULTS: The findings showed water microbial contamination in all the dental surgeries; the proportion of water samples with microbial levels above those recommended decreased during working. With regard

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

2008-01-01

9

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...

10

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 freshwater ecosystems for many goods and services (drinking water, recreational facilities...), which places application and aerial spraying (e.g. Carter, 2000). Microbial communities in freshwater ecosystems

11

Microbial contamination of used dental handpieces.  

PubMed

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

Smith, Gordon; Smith, Andrew

2014-09-01

12

Cadmium Selenium Testing for Microbial Contaminants  

NASA Technical Reports Server (NTRS)

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.

2003-01-01

13

Field Analysis of Microbial Contamination Using Three Molecular Methods in Parallel  

NASA Technical Reports Server (NTRS)

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).

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

2010-01-01

14

Use of a simple catalase assay for assessment of aerobic microbial contamination on vegetables  

Microsoft Academic Search

This paper presents a rapid catalase test for monitoring the aerobic microbial contamination associated with vegetables. The\\u000a microbial loads of celery, bell pepper and ready-to-eat salad were serially tested over a 2-week period under common storage\\u000a conditions. At each time point, samples were surface-sampled for catalase activity with a Pasteur pipette method in 5 min.\\u000a Simultaneously, the aerobic viable microbial counts

Rebecca J. Ye; Vivian C. H. Wu

2011-01-01

15

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

PubMed

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

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

2014-09-19

16

Microbial Biogeography of Public Restroom Surfaces  

PubMed Central

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

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

2011-01-01

17

Oxidation of aromatic contaminants coupled to microbial iron reduction  

USGS Publications Warehouse

THE contamination of sub-surface water supplies with aromatic compounds is a significant environmental concern1,2. As these contaminated sub-surface environments are generally anaerobic, the microbial oxidation of aromatic compounds coupled to nitrate reduction, sulphate reduction and methane production has been studied intensively1-7. In addition, geochemical evidence suggests that Fe(III) can be an important electron acceptor for the oxidation of aromatic compounds in anaerobic groundwater. Until now, only abiological mechanisms for the oxidation of aromatic compounds with Fe(III) have been reported8-12. Here we show that in aquatic sediments, microbial activity is necessary for the oxidation of model aromatic compounds coupled to Fe(III) reduction. Furthermore, a pure culture of the Fe(III)-reducing bacterium GS-15 can obtain energy for growth by oxidizing benzoate, toluene, phenol or p-cresol with Fe(III) as the sole electron acceptor. These results extend the known physiological capabilities of Fe(III)-reducing organisms and provide the first example of an organism of any type which can oxidize an aromatic hydrocarbon anaerobically. ?? 1989 Nature Publishing Group.

Lovley, D.R.; Baedecker, M.J.; Lonergan, D.J.; Cozzarelli, I.M.; Phillips, E.J.P.; Siegel, D.I.

1989-01-01

18

Microbial contamination monitoring and control during human space missions  

NASA Astrophysics Data System (ADS)

The ubiquity and resilience of microorganisms makes them unavoidable in most environments including space habitats. The impaired immune system of astronauts in flight raises the level of concern about disease risk during human space missions and additionally these biological contaminants may affect life support systems and hardware. In this review, the microbial contamination observed in manned space stations and in particular the International Space Station ISS will be discussed, demonstrating that it is a microbiologically safe working and living habitat. Microbial contamination levels were in general below the implemented quality standards, although, occasional contamination hazard reports indicate that the current prevention and monitoring strategies are the strict minimum.

Van Houdt, Rob; Mijnendonckx, Kristel; Leys, Natalie

2012-01-01

19

Subsurface characterization of groundwater contaminated by landfill leachate using microbial community profile  

E-print Network

Subsurface characterization of groundwater contaminated by landfill leachate using microbial. In this landfill leachate application, the weighted SOM assembles the microbial community data from monitoring (2011), Subsurface characterization of groundwater contaminated by landfill leachate using microbial

Vermont, University of

20

Rhizosphere Microbial Characterization in Petroleum-Contaminated Soil  

Microsoft Academic Search

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

M. Katherine Banks; Hadessa Mallede; Karrie Rathbone

2003-01-01

21

Microbial Janitors: Enabling natural microbes to clean up uranium contamination  

E-print Network

to the development of the atomic bomb. Uranium enrichment activities on the Oak Ridge Reservation in the 1940s untilMicrobial Janitors: Enabling natural microbes to clean up uranium contamination Oak Ridge then the uranium and nitrate contamination has spread through the ground and now covers an area of about 7 km

22

Surface Contamination Surface contamination from radioactive isotopes is a source of background in the Borex-  

E-print Network

Chapter 5 Surface Contamination Surface contamination from radioactive isotopes is a source contamination is primarily a problem because the radioactive contaminants can be trans- ferred from the surfaces detector components that come in contact with the scintillator. Preventing radioactive contamination

23

Phylogenetic & Physiological Profiling of Microbial Communities of Contaminated Soils/Sediments: Identifying Microbial consortia...  

SciTech Connect

The goals of this study were: (1) survey the microbial community in soil samples from a site contaminated with heavy metals using new rapid molecular techniques that are culture-independent; (2) identify phylogenetic signatures of microbial populations that correlate with metal ion contamination; and (3) cultivate these diagnostic strains using traditional as well as novel cultivation techniques in order to identify organisms that may be of value in site evaluation/management or bioremediation.

Terence L. Marsh

2004-05-26

24

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 ...

25

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 ...

26

Environmental surface cleanliness and the potential for contamination during handwashing  

Microsoft Academic Search

Effective handwashing (including drying) is important in infection control. The ability of the various stages of handwashing to decrease skin-surface microbial counts has been documented. However, an important element, environmental surface cleanliness, and the potential for contamination of hands during the process has not been well studied or quantified. An examination of the adenosine triphosphate (a measure of residual organic

Christopher J. Griffith; Rifhat Malik; Rose A. Cooper; Nick Looker; Barry Michaels

2003-01-01

27

Microbial contamination of antiseptic-soaked cotton balls.  

PubMed

We investigated microbial contamination of in-use antiseptics at a hospital. No microbial contamination was observed in 70 samples of 0.02% benzalkonium chloride solution (500-ml volume), 70 samples of 1% titratable I2 povidone-iodine solution (250-ml volume), or 15 samples of 0.1% ethacridine lactate solution (500-ml volume) during use in reduced amounts. Nor was any microbial contamination observed in 70 samples of cotton balls soaked in 1% titratable I2 povidone-iodine solution in canisters or cotton gauze soaked in 70% (w/v) ethanol solution in canisters. However, among 70 samples of cotton balls soaked in 0.02% benzalkonium chloride solution in canisters, 6 (8.6%) were contaminated with 10(4) to 10(6) viable cells/ml. The microbial species detected were glucose non-fermentative bacilli such as Alcaligenes xylosoxidans and Pseudomonas putida. The contaminants obtained from cotton balls soaked in 0.02% benzalkonium chloride solution did not proliferate in that solution or in distilled water but showed rapid growth in the cotton balls soaked in either of these liquids. These findings suggested that benzalkonium chloride solution tends to become contaminated when cotton balls are immersed. Therefore, cotton balls soaked in benzalkonium chloride solution are not recommended as an antiseptic. When no other choice is available, the cotton balls should be soaked in benzalkonium chloride solution at the time of usage. PMID:9212987

Oie, S; Kamiya, A

1997-06-01

28

Microbial Contamination of Antiseptics and Disinfectants  

Microsoft Academic Search

Objective : To study the bacterial contamination of antiseptics and disinfections in-use and the risk factors for contamination. Material and Method : Bacterial contamination of antiseptics and disinfectants was done by culturing in-use solutions. Eight commonly used solutions were studied : alcohol 70%, chlorhexidine 4%, and 0.5%, povidone iodine 7.5% and 10%, tincture iodine 1-2%, lysol 2% and sodium hypochlorite

Somwang Danchaivijitr; Chertsak Dhiraputra; Yong Rongrungruang; Nitaya Srihapol RN; Varaporn Pumsuwan

2005-01-01

29

Surface micropattern limits bacterial contamination  

PubMed Central

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

2014-01-01

30

Ecogenomics of microbial communities in bioremediation of chlorinated contaminated sites  

PubMed Central

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

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

2012-01-01

31

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

PubMed

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

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

2012-10-01

32

EPA BIBLIOGRAPHY ON SURFACE CONTAMINATION  

EPA Science Inventory

As a part of the attempt to maintain technical currency, the toxics Control Branch, Risk Reduction Engineering Laboratory of the USEPA conducts an ongoing review of the literature dealing with surface contamination. riginally, this effort dealt primarily with asbestos in surface ...

33

Bioremediation of petroleum contaminated soil using vegetation: A microbial study  

Microsoft Academic Search

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

Euisang Lee; M. K. Banks

1993-01-01

34

Response of a salt marsh microbial community to metal contamination  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

35

Molecular Profiling of Microbial Communities from Contaminated  

SciTech Connect

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.

Robb, Frank T.

1999-06-01

36

The use of molecular techniques to characterize the microbial communities in contaminated soil and water  

Microsoft Academic Search

Traditionally, the identification and characterization of microbial communities in contaminated soil and water has previously been limited to those microorganisms that are culturable. The application of molecular techniques to study microbial populations at contaminated sites without the need for culturing has led to the discovery of unique and previously unrecognized microorganisms as well as complex microbial diversity in contaminated soil

Seidu Malik; Michael Beer; Mallavarapu Megharaj; Ravi Naidu

2008-01-01

37

A theoretical microbial contamination model for a human Mars mission  

NASA Astrophysics Data System (ADS)

Contamination from a human presence on Mars could significantly compromise the search for extraterrestrial life. In particular, the difficulties in controlling microbial contamination, the potential for terrestrial microbes to grow, evolve, compete, and modify the Martian environment, and the likely microbial nature of putative Martian life, make microbial contamination worthy of focus as we begin to plan for a human mission to Mars. This dissertation describes a relatively simple theoretical model that can be used to explore how microbial contamination from a human Mars mission might survive and grow in the Martian soil environment surrounding a habitat. A user interface has been developed to allow a general practitioner to choose values and functions for almost all parameters ranging from the number of astronauts to the half-saturation constants for microbial growth. Systematic deviations from a baseline set of parameter values are explored as potential plausible scenarios for the first human Mars missions. The total viable population and population density are the primary state variables of interest, but other variables such as the total number of births and total dead and viable microbes are also tracked. The general approach was to find the most plausible parameter value combinations that produced a population density of 1 microbe/cm3 or greater, a threshold that was used to categorize the more noteworthy populations for subsequent analysis. Preliminary assessments indicate that terrestrial microbial contamination resulting from leakage from a limited human mission (perhaps lasting up to 5 months) will not likely become a problematic population in the near-term as long as reasonable contamination control measures are implemented (for example, a habitat leak rate no greater than 1% per hour). However, there appear to be plausible, albeit unlikely, scenarios that could cause problematic populations, depending in part on (a) the initial survival fraction and death rate of microbes that are leaked into the Martian environment, which depends largely on the possibility for protection from the high UV radiation environment on Mars, (b) organic nutrient availability, and (c) liquid water availability, which is likely to be the limiting survival and growth factor.

Lupisella, Mark Lewis

38

Apparatus for Sampling Surface Contamination  

NASA Technical Reports Server (NTRS)

An apparatus denoted a swab device has been developed as a convenient means of acquiring samples of contaminants from surfaces and suspending the samples in liquids. (Thereafter, the liquids can be dispensed, in controlled volumes, into scientific instruments for analysis of the contaminants.) The swab device is designed so as not to introduce additional contamination and to facilitate, simplify, and systematize the dispensing of controlled volumes of liquid into analytical instruments. The swab device is a single apparatus into which are combined all the equipment and materials needed for sampling surface contamination. The swab device contains disposable components stacked together on a nondisposable dispensing head. One of the disposable components is a supply cartridge holding a sufficient volume of liquid for one complete set of samples. (The liquid could be clean water or another suitable solvent, depending on the application.) This supply of liquid is sealed by Luer valves. At the beginning of a sampling process, the user tears open a sealed bag containing the supply cartridge. A tip on the nondisposable dispensing head is engaged with a Luer valve on one end of the supply cartridge and rotated, locking the supply cartridge on the dispensing head and opening the valve. The swab tip includes a fabric swab that is wiped across the surface of interest to acquire a sample. A sealed bag containing a disposable dispensing tip is then opened, and the swab tip is pushed into the dispensing tip until seated. The dispensing head contains a piston that passes through a spring-loaded lip seal. The air volume displaced by this piston forces the liquid out of the supply cartridge, over the swab, and into the dispensing tip. The piston is manually cycled to enforce oscillation of the air volume and thereby to cause water to flow to wash contaminants from the swab and cause the resulting liquid suspension of contaminants to flow into the dispensing tip. After several cycles to ensure adequate mixing, liquid containing the suspended contaminant sample is dispensed. The disposable components are then removed from the dispensing head, which may then be reused with a fresh set of disposable components.

Wells, Mark

2008-01-01

39

Biofilms: Microbial Life on Surfaces  

Microsoft Academic Search

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

Rodney M. Donlan

2002-01-01

40

How to deal with PCR contamination in molecular microbial ecology.  

PubMed

Microbial ecology studies often use broad-range PCR primers to obtain community profiles. Contaminant microbial DNA present in PCR reagents may therefore be amplified together with template DNA, resulting in unrepeatable data which may be difficult to interpret, especially when template DNA is present at low levels. One possible decontamination method consists in pre-treating PCR mixes with restriction enzymes before heat-inactivating those enzymes prior to the start of the PCR. However, this method has given contrasting results, including a reduction in PCR sensitivity. In this study, we tested the efficiency of two different enzymes (DNase 1 and Sau3AI) as well as the effect of dithiothreitol (DTT), a strong reducing agent, in the decontamination procedure. Our results indicate that enzymatic treatment does reduce contamination levels. However, DNase 1 caused substantial reductions in the bacterial richness found in communities, which we interpret as a result of its incomplete inactivation by heat treatment. DTT did help maintain bacterial richness in mixes treated with DNase 1. No such issues arose when using Sau3AI, which therefore seems a more appropriate enzyme. In our study, four operational taxonomic units (OTU) decreased in frequency and relative abundance after treatment with Sau3AI and hence are likely to represent contaminant bacterial DNA. We found higher within-sample similarity in community structure after treatment with Sau3AI, probably better reflecting the initial bacterial communities. We argue that the presence of contaminant bacterial DNA may have consequences in the interpretation of ecological data, especially when using low levels of template DNA from highly diverse communities. We advocate the use of such decontaminating approaches as a standard procedure in microbial ecology. PMID:25004997

Mennerat, Adèle; Sheldon, Ben C

2014-11-01

41

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

USGS Publications Warehouse

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.

Cloud, P.; Morrison, K.

1979-01-01

42

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 ...

43

The potential reduction of microbial contamination of central venous catheters.  

PubMed

The microbial contamination of stopcock entry ports attached to central venous catheters (CVC) was determined using a specially designed swab. The swab was made of a highly porous material, Porex, and was designed to fit exactly into the entry port of stopcocks. The swab was used to determine the frequency of microbial contamination of entry ports attached to CVC in patients located on an Intensive Care Unit. Of the 200 swabs obtained 44 (22%) contained microorganisms. Coagulase-negative staphylococci were recovered from 43 of the swabs and diphtheroid bacilli from 1 swab. In vitro studies were carried out to investigate the efficiency of the swab in removing excess residual fluid and organisms from entry ports. The swab absorbed relatively large numbers of bacteria within seconds. When entry ports were inoculated with between 10(3) and 10(5) cfu of either Staphylococcus epidermidis or Klebsiella pneumoniae greater than 99% of the organisms were absorbed by the swab (P < 0.01). The absorbent swab was more efficient at removing S. epidermidis from the entry port when compared to a standard cotton swab (P < 0.01). In vitro this absorbent swab reduced the potential for catheter contamination resulting from migration of organisms from the entry port via the intraluminal route. The use of the swab in the clinical situation may reduce the incidence of CVC-related infections. PMID:7636276

Tebbs, S E; Trend, V; Elliott, T S

1995-03-01

44

Microbial contamination of drinking water in Pakistan-a review.  

PubMed

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

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

2014-12-01

45

Potential sources of microbial contamination in unpasteurized apple cider.  

PubMed

A study was conducted to identify possible sources of microbial contamination and to assess the effect of good cleaning and sanitation practices on the microbial quality and safety of unpasteurized apple cider. Raw unwashed apples, washed apples, cleaning water, fresh cider, and finished cider samples were collected from five Ontario producers over 4 months and microbiologically tested. Total coliforms were found in 31, 71 and 38% of the unwashed apple, water, and washed apple samples, respectively. Escherichia coli was found in 40% of the water samples from one producer alone. The washing step was identified as a potential source of contamination, possibly due to water in the dump tanks seldom being refreshed, and because scrubbers, spray nozzles, and conveyors were not properly cleaned and sanitized. Higher total coliform counts (P < 0.0001) and prevalence (P < 0.0001) in fresh cider compared with those in unwashed apples and washed apples indicated considerable microbial buildup along the process, possibly explained by the lack of appropriate equipment sanitation procedures. Results showed that producers who had better sanitary practices in place had lower (P < 0.001) total coliform prevalence than the rest of the producers. Overall results show that good sanitation procedures are associated with improved microbial quality of fresh cider in terms of total coliforms and that operators who pasteurize and/or UV treat their product should still be required to have a sound good manufacturing practices program in place to prevent recontamination. Cryptosporidium parvum, an important pathogen for this industry, was found in different sample types, including washed apples, water, and fresh and finished cider. PMID:16416911

Garcia, Luis; Henderson, John; Fabri, Martha; Oke, Moustapha

2006-01-01

46

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

PubMed Central

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

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

2011-01-01

47

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

PubMed Central

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

Gough, Heidi L; Stahl, David A

2011-01-01

48

Differences in Hyporheic-Zone Microbial Community Structure along a Heavy-Metal Contamination Gradient  

PubMed Central

The hyporheic zone of a river is nonphotic, has steep chemical and redox gradients, and has a heterotrophic food web based on the consumption of organic carbon entrained from downwelling surface water or from upwelling groundwater. The microbial communities in the hyporheic zone are an important component of these heterotrophic food webs and perform essential functions in lotic ecosystems. Using a suite of methods (denaturing gradient gel electrophoresis, 16S rRNA phylogeny, phospholipid fatty acid analysis, direct microscopic enumeration, and quantitative PCR), we compared the microbial communities inhabiting the hyporheic zone of six different river sites that encompass a wide range of sediment metal loads resulting from large base-metal mining activity in the region. There was no correlation between sediment metal content and the total hyporheic microbial biomass present within each site. However, microbial community structure showed a significant linear relationship with the sediment metal loads. The abundances of four phylogenetic groups (groups I, II, III, and IV) most closely related to ?-, ?-, and ?-proteobacteria and the cyanobacteria, respectively, were determined. The sediment metal content gradient was positively correlated with group III abundance and negatively correlated with group II abundance. No correlation was apparent with regard to group I or IV abundance. This is the first documentation of a relationship between fluvially deposited heavy-metal contamination and hyporheic microbial community structure. The information presented here may be useful in predicting long-term effects of heavy-metal contamination in streams and provides a basis for further studies of metal effects on hyporheic microbial communities. PMID:12957946

Feris, Kevin; Ramsey, Philip; Frazar, Chris; Moore, Johnnie N.; Gannon, James E.; Holben, William E.

2003-01-01

49

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...

50

Surface evaluation of UV-degraded contamination  

NASA Technical Reports Server (NTRS)

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.

Connatser, Robert; Hadaway, James B.

1992-01-01

51

Surface contamination on LDEF exposed materials  

NASA Technical Reports Server (NTRS)

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.

Hemminger, Carol S.

1992-01-01

52

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

PubMed

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

Fu, Ling-Lin; Li, Jian-Rong

2014-01-01

53

Diamond Shaving of Contaminated Concrete Surfaces  

Microsoft Academic Search

Decommissioning and decontamination of existing facilities presents technological challenges. One major challenge is the removal of surface contamination from concrete floors and walls while eliminating the spread of contamination and volumetric reduction of the waste stream. Numerous methods have been tried with a varying degree of success. Recent technology has made this goal achievable and has been used successfully. This

Lisa K

2008-01-01

54

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...

55

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...

56

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...

57

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

E-print Network

) 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...

Thornburg, Nathaniel David

2012-06-07

58

Characterization of Microbial Communities from Pristine and Chlorinated-Ethene-Contaminated Landfill Groundwater.  

National Technical Information Service (NTIS)

Molecular, phospholipid fatty acid analysis (PLFA), and substrate utilization (BIOLOG) techniques were used to assess structural and functional differences between microbial communities from a chlorinated-ethene (CE)-contaminated groundwater at a sanitary...

R. L. Brigmon

2002-01-01

59

Comparative efficiency of nitrocellulose membranes versus RODAC plates in microbial sampling on surfaces.  

PubMed

The efficiency of nitrocelluose membranes in collecting microbial samples from rigid and flat surfaces has been studied and compared with that of RODAC plates. The experimental design was based on multiple samplings in close succession in the same place. The median efficiency of membrane filters (78.55) was higher than that of RODAC plates (65.37). The data demonstrate the reliability of membranes and show that membranes are more efficient than RODAC plates as a sampling method for measuring surface microbial contamination. PMID:10204121

Poletti, L; Pasquarella, C; Pitzurra, M; Savino, A

1999-03-01

60

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

Microsoft Academic Search

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 ad- dressed

Y. SHI; M. D. ZWOLINSKI; M. E. SCHREIBER; J. M. BAHR; G. W. SEWELL; W. J. HICKEY

1999-01-01

61

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

PubMed

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

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

2014-05-01

62

Calculating Obscuration Ratios Of Contaminated Surfaces  

NASA Technical Reports Server (NTRS)

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.

Barengoltz, Jack B.

1989-01-01

63

CTF Surface Contamination and External Backgrounds  

E-print Network

Chapter 9 CTF Surface Contamination and External Backgrounds The preceding chapter included a thorough analysis of internal events in the CTF, those happening in the volume of scintillator in the CTF. Recall that surface events are defined as those produced by radioactive materials embedded

64

Evaluation of microbially influenced degradation as a method for the decontamination of radioactively contaminated concrete  

SciTech Connect

Because there are literally square kilometers of radioactively contaminated concrete surfaces within the US Department of Energy (DOE) complex, the task (both scope and cost) of decontamination is staggering. Complex-wide cleanup using conventional methodology does not appear to be feasible for every facility because of prioritization, cost, and manual effort required. The authors are investigating the feasibility of using microbially influenced degradation (MID) of concrete as a unique, innovative approach for the decontamination of concrete. Currently, work is being conducted to determine the practicality and cost effectiveness of using this environmentally acceptable method for decontamination of large surface concrete structures. Under laboratory conditions, the biodecontamination process has successfully been used to remove 2 mm of the surface of concrete slabs. Subsequently, initial field application data from an ongoing pilot-scale demonstration have shown that an average of 2 mm of surface can be removed from meter-square areas of contaminated concrete. The cost for the process has been estimated as $1.29/m{sup 2}. Methodologies for field application of the process are being developed and will be tested. This paper provides information on the MID process, laboratory evaluation of its use for decontamination, and results from the pilot field application.

Rogers, R.D.; Hamilton, M.A.; Nelson, L.O. [Idaho National Engineering Lab., Idaho Falls, ID (United States). Biotechnology Dept.; Benson, J.; Green, M. [British Nuclear Fuels PLC, Preston (United Kingdom). Company Research Lab.

1997-12-31

65

Effect of organic amendments on microbial activity in chlorpyrifos contaminated soil.  

PubMed

The aim of this research was to study the inhibitory effect of chlorpyrifos (CPF) on soil microbial activity and to evaluate the efficacy of different organic amendments as a biostimulation agent for sustaining the microbial activity and thereby assisting in the remediation of CPF (10 ppm) contaminated soil. Experiments were carried out under controlled conditions (37 °C) up to 74 days; CPF was analyzed by GC-ECD while dehydrogenase activity (DHA) was measured as one of the indices of soil microbial activity. Throughout the experiment, there was higher microbial activity in uncontaminated soil (S) as compared to CPF contaminated soil (SP) and overall a considerably high reduction (63.51%) in average DHA was noticed in CPF contaminated soil. Organic amendments enhanced the microbial activity over unamended CPF contaminated soil. The trend of DHA on 24th day was MS (SP + 1% Mushroom Spent) >VC (SP + 1% Vermicompost) >BS (SP + 1% Biogas Slurry) >SP (Soil spiked with 10 ppm CPF) >FM (SP + 1% Farmyard Manure). The enhancement in pesticide dissipation over the unamended soil showed the following trend VC (37%)>MS (24%) >FM (1.9%). In spite of sufficient DHA, BS could not enhance pesticide dissipation over the unamended soil (SP). These results indicate the potential of vermicompost and mushroom spent compost as suitable biostimulation agents to sustain the microbial activity in CPF contaminated soil. PMID:21035243

Kadian, Neeru; Malik, Anushree; Satya, Santosh; Dureja, Prem

2012-03-01

66

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

Microsoft Academic Search

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

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

2010-01-01

67

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

SciTech Connect

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.

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

68

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

PubMed

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

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

2012-09-01

69

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

PubMed

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

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

1997-01-01

70

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

PubMed Central

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

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

2007-01-01

71

Key players and team play: anaerobic microbial communities in hydrocarbon-contaminated aquifers.  

PubMed

Biodegradation of anthropogenic pollutants in shallow aquifers is an important microbial ecosystem service which is mainly brought about by indigenous anaerobic microorganisms. For the management of contaminated sites, risk assessment and control of natural attenuation, the assessment of in situ biodegradation and the underlying microbial processes is essential. The development of novel molecular methods, "omics" approaches, and high-throughput techniques has revealed new insight into complex microbial communities and their functions in anoxic environmental systems. This review summarizes recent advances in the application of molecular methods to study anaerobic microbial communities in contaminated terrestrial subsurface ecosystems. We focus on current approaches to analyze composition, dynamics, and functional diversity of subsurface communities, to link identity to activity and metabolic function, and to identify the ecophysiological role of not yet cultured microbes and syntrophic consortia. We discuss recent molecular surveys of contaminated sites from an ecological viewpoint regarding degrader ecotypes, abiotic factors shaping anaerobic communities, and biotic interactions underpinning the importance of microbial cooperation for microbial ecosystem services such as contaminant degradation. PMID:22476263

Kleinsteuber, Sabine; Schleinitz, Kathleen M; Vogt, Carsten

2012-05-01

72

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

PubMed

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

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

2014-01-01

73

Changes in Microbial Populations and Enzyme Activities During the Bioremediation of Oil-Contaminated Soil  

Microsoft Academic Search

In the process of bioremediation in the soil contaminated by different oil concentrations, the changes in the microbial numbers\\u000a (bacteria and fungi) and the enzyme (catalase (CAT), polyphenol oxidase (PPO) and lipase) activities were evaluated over a\\u000a 2-year period. The results showed that the microbial numbers after 2-year bioremediation were one to ten times higher than\\u000a those in the initial.

Xin Lin; Xiaojun Li; Tieheng Sun; Peijun Li; Qixing Zhou; Lina Sun; Xiaojun Hu

2009-01-01

74

Hard Surface Biocontrol in Hospitals Using Microbial-Based Cleaning Products  

PubMed Central

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

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

2014-01-01

75

Microbial ecology of food contact surfaces and products of small-scale facilities producing traditional sausages.  

PubMed

The microbial status in 7 small-scale facilities (SSFs) producing traditional fermented and/or dry sausages was investigated. It was shown that the hygienic status of the processing environment and equipment plays an essential role in the microbial stability and safety of the final products. The current study revealed that the majority of the sampling sites (control points) tested were highly (>4 log CFU/cm(2)) contaminated by spoilage flora (i.e. Pseudomonas, Enterobacteriaceae), with knives, tables and mincing machines being the most heavily contaminated surfaces. Moreover, Listeria monocytogenes, Salmonella spp. and Staphylococcus aureus were detected in 11.7%, 26.4%, and 11.7% of the food contact surfaces, respectively. The presence of these pathogens seemed to be associated with high numbers of one or more specific groups of the 'house-flora' on the sampling sites of the facilities; however, high numbers of 'house-flora' do not always suggest the presence of pathogens. With regard to product samples, batter samples were heavily contaminated with the 'house-flora' present on surfaces and equipment of the processing facilities while by the end of processing (final products) LAB constituted the predominant microbial flora of all products. The low initial levels of S. aureus and Salmonella found in batter samples as well as the combination of hurdles (mainly a(w)<0.92, average pH ca. <5.0 and competitive effect of natural flora) in the final products were able to inhibit and/or eliminate these pathogens; however, the detection of L. monocytogenes in 3 out of the 7 final products examined is indicative of cross-contamination. Our findings further indicate that inadequate hygiene practices within small-scale-processing facilities may result in loss of microbial control. Therefore, this study addresses the need for strict control measures within SSFs producing traditional fermented sausages. PMID:18206774

Gounadaki, Antonia S; Skandamis, Panagiotis N; Drosinos, Eleftherios H; Nychas, George-John E

2008-04-01

76

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

PubMed

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

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

2014-02-01

77

TYPES AND EFFECTS OF MICROBIAL CONTAMINATION OF GROUNDWATER  

EPA Science Inventory

Waterborne illness can be contracted by ingestion of contaminated water or ice; during bathing, swimming, or wading; from inhalation of aerosols, gases, or vapors from contaminated water or waste water. he general unavailability of water for bathing and washing also contributes a...

78

Hyporheic microbial community development is a sensitive indicator of metal contamination.  

PubMed

Accurate natural resource damage assessment necessitates monitoring organisms or communities that respond most sensitively to contaminants. Observational studies have demonstrated a correlation between fluvial heavy metal deposition and hyporheic microbial community structure. To establish a causal relationship between sediment metal content and the structure of colonizing bacterial communities, we performed a controlled field experiment River sediments of 1.75-2.36 mm in diameter with five different contaminant concentrations were collected from an environmental metal contamination gradient. Sediments were sterilized and then recolonized by incubation in the hyporheic zone of an uncontaminated river (i.e., a common garden experiment was performed). A significant correlation between hyporheic microbial community structure and heavy metal contamination (R2 = 0.81) was observed. The abundance of two phylogenetic groups was highly correlated with the level of heavy metal contamination (Group I, R2 = 0.96; Group III, R2 = 0.96, most closely affiliated with the alpha- and gamma-proteobacteria, respectively). Microbial community structural responses were detected at metal concentrations an order of magnitude lower than those previously reported to impact benthic macroinvertebrate communities. We conclude that hyporheic microbial communities could offer the most sensitive method for assessing natural resource damage in lotic ecosystems in response to fluvial heavy metal deposition. PMID:19746707

Feris, Kevin P; Ramsey, Philip W; Gibbons, Sean M; Frazar, Chris; Rillig, Matthias C; Moore, Johnnie N; Gannon, James E; Holben, William E

2009-08-15

79

Microbial metabolism of polycyclic aromatic hydrocarbons (PAH) in creosote contaminated soils  

SciTech Connect

Creosote contaminated sites are of environmental significance due to the high concentrations of toxic and/or mutagenic PAH usually found at these sites. Microbial degradation of PAH can be seen as a novel form of contaminant detoxification. This paper describes the microbial degradation of PAH in creosote contaminated soils using (9-{sup 14}C) phenanthrene as a model PAH. Microbial metabolism was assessed with a mass balance approach as well as identification of PAH metabolites by GC/MS/FTIR. The mass balance accounted for the amount portion of the added phenanthrene. To confirm the effectiveness of microbial degradation to decrease soil toxicity, the Microtox{reg_sign} and Mutatox{reg_sign} assays were used to monitor toxicity of the creosote soils throughout the experiments. Mass balance results indicated that phenanthrene was readily mineralized in the contaminated soils, while metabolite production accounted for only a minor portion of the added phenanthrene. Toxicity of contaminated soils increased slightly early in the incubation and then decreased over longer time periods. Mutagenicity of soils, however, did not decrease appreciably over a 3-month time period. The identity of metabolic products found in the soils will be discussed.

Carmichael, L.M.; Pfaender, F.K. [Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Environmental Sciences and Engineering

1994-12-31

80

SRP Meeting: Surface and Airborne Contamination  

Microsoft Academic Search

AWE Aldermaston, 26-27 June 2000AWE Aldermaston recently opened its doors to both United Kingdom and international delegates for a two-day scientific meeting and tour on the subject of 'Surface and Airborne Contamination'. The meeting was held on the 26-27 June 2000 and involved nearly 200 delegates and 8 speakers from the defence, nuclear industries, health sector and begulatory bodies.Tours were

2000-01-01

81

Radiation treatment of herb tea for the reduction of microbial contamination (Flores chamomillae)  

NASA Astrophysics Data System (ADS)

A survey of microbiological contamination of dried chamomile flowers indicates the presence of thermophilic bacteria up to the level of 10 4 per gram. This material often contains insecticides which have been used to reduce post-harvest losses. This work was undertaken in order to study the feasibility of radiation treatment of dried chamomile flowers as the only acceptable process for reduction of microbial contamination and as an alternative to chemical treatment. The main microbial contaminants were identified and typical contamination levels established. Survival curves of the irradiated microflora were obtained as a function of gamma radiation dose. Chemical composition of chamomile oil was followed by spectroscopy, thin layer and gas chromatography. No untoward effects of radiation treatment on active components were found, which indicates the usefulness of radiation treatment of dry flowers.

Katušin-Ražem, B.; Ražem, D.; Dvornik, I.; Mati?, S.

82

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

Microsoft Academic Search

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

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

2006-01-01

83

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

Microsoft Academic Search

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

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

2007-01-01

84

Recommended tritium surface contamination release guides  

SciTech Connect

This document was prepared to provide scientific basis for recommended changes in specific limits for tritium surface contamination in DOE Order 5480.11. A summary of the physical and biological characteristics of tritium has been provided that illustrate the unique nature of this radionuclide when compared to other pure beta emitters or to beta-gamma emitting radionuclides. This document is divided into nine sections. The introduction and the purpose and scope are addressed in Section 1.0 and Section 2.0, respectively. Section 3.0 contains recommended interpretation of terms used in this document. Section 4.0 addresses recommended methods for evaluating surface contamination. Biological and physical characteristics of tritium compounds are discussed in Section 5.0, as they relate to tritium radiotoxicity. Scenarios and dose calculations for selected, conservatively limiting cases of tritium intake are given and discussed in Section 6.0 and Section 7.0. Section 8.0 provides conclusions on the information given and recommendations for changes in the surface contamination limits for total tritium to 1 {times} 10{sup 6} dpm per 100 cm{sup 2}. 30 refs., 2 tabs.

Johnson, J.R.; Draper, D.G.; Foulke, J.D.; Hafner, R.S.; Jalbert, R.A.; Kennedy, W.E.; Myers, D.S.; Strain, C.D. (USDOE Tritium Surface Contamination Limits Committee, Washington, DC (USA))

1991-03-01

85

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

PubMed

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

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

2014-05-01

86

Assessment of surface contamination with contact mechanics  

SciTech Connect

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 are trying to address is at what level of contamination does adhesive strength decrease. The use of contact mechanics, the JKR method, is a good approach for studying this question. Another approach being studied is the use of interracial fracture mechanics. The model contaminant is hexadecane--non-polar, medium molecular weight hydrocarbon fluid. They choose hexadecane because it replicates typical machining fluids, is nonreactive with Al surfaces, and should not dissolve readily into the adhesive systems of interest. The application of a uniform, controllable and reproducible hexadecane layer on Al surfaces has proven to be difficult. A primary concern is whether studies of model systems can be extended to systems of technological interest. The JKR theory is a continuum mechanics model of contact between two solid spheres that was developed by Johnson, Kendall and Roberts. The JKR theory is an extension of Hertzian contact theory and attributes the additional increase in the contact area between a soft elastomeric hemisphere to adhesive forces between the two surfaces. The JKR theory allows a direct estimate of the surface free energy of interface as well as the work of adhesion (Wa) between solids. Early studies performed in this laboratory involved the determination of Wa between silicone (PDMS) and Al surfaces in order to establish the potential adhesive failure mechanisms. However, the JKR studies using commercial based PDMS [poly(dimethylsiloxane)] was fraught with difficulty that were attributed to the additives used in commercial PDMS systems. The authors could not discriminate hydrogen-bonding effects between Al{sub 2}O{sub 3} and hydroxyl groups in the PDMS, and other possible bonding mechanisms. A model PDMS elastomer and polymer treatments were developed for studying solid surfaces by measuring the degree of self-adhesion hysteresis as indicator of surface properties. The goal of this work is to measure the adhesion between PDMS/Al surfaces -- contaminated and two cleaning techniques. A custom-made JKR apparatus is used to determine the amount of hysteresis and Wa.

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

2000-02-21

87

Rapid and Robust Detection Methods for Poison and Microbial Contamination  

E-print Network

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 ...

Lu, Peter J.

88

10 CFR Appendix D to Part 835 - Surface Contamination Values  

Code of Federal Regulations, 2013 CFR

... 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...

2013-01-01

89

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

PubMed

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

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

2014-07-01

90

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

PubMed Central

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

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

2012-01-01

91

Assessing the microbial community and functional genes in a vertical soil profile with long-term arsenic contamination.  

PubMed

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, NO(3) (-) 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

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

2012-01-01

92

Validation studies on an online monitoring system for reducing faecal and microbial contamination on beef carcasses  

Microsoft Academic Search

The objective of this research was to establish the reduction in the incidence of carcass faecal contamination and microbial counts that could be achieved in a beef slaughter plant using a novel information technology based online monitoring system. On 18 separate visits over the course of 6 months, every carcass (approximately 500 per day) was examined at the final inspection

A. Tergney; D. J. Bolton

2006-01-01

93

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

E-print Network

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

Auckland, University of

94

Subsurface ecosystem resilience: long-term attenuation of subsurface contaminants supports a dynamic microbial community  

Microsoft Academic Search

The propensity for groundwater ecosystems to recover from contamination by organic chemicals (in this case, coal-tar waste) is of vital concern for scientists and engineers who manage polluted sites. The microbially mediated cleanup processes are also of interest to ecologists because they are an important mechanism for the resilience of ecosystems. In this study we establish the long-term dynamic nature

Jane M Yagi; Edward F Neuhauser; John A Ripp; David M Mauro; Eugene L Madsen

2010-01-01

95

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...

96

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

USGS Publications Warehouse

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.

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

1988-01-01

97

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

Microsoft Academic Search

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

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

2000-01-01

98

Hand-pumps as reservoirs for microbial contamination of well water  

E-print Network

Hand-pumps as reservoirs for microbial contamination of well water Andrew S. Ferguson, Brian J spiked with E. coli. All hand-pumps were connected to reservoirs of sterile water and flushed. Faecal hand-pump, E. coli was observed in the discharge over 125 days (t50 ¼ 8 days) and found to attach

van Geen, Alexander

99

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

PubMed

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

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

2012-01-01

100

Impact of Long-Term Diesel Contamination on Soil Microbial Community Structure  

PubMed Central

Microbial community composition and diversity at a diesel-contaminated railway site were investigated by pyrosequencing of bacterial and archaeal 16S rRNA gene fragments to understand the interrelationships among microbial community composition, pollution level, and soil geochemical and physical properties. To this end, 26 soil samples from four matrix types with various geochemical characteristics and contaminant concentrations were investigated. The presence of diesel contamination significantly impacted microbial community composition and diversity, regardless of the soil matrix type. Clean samples showed higher diversity than contaminated samples (P < 0.001). Bacterial phyla with high relative abundances in all samples included Proteobacteria, Firmicutes, Actinobacteria, Acidobacteria, and Chloroflexi. High relative abundances of Archaea, specifically of the phylum Euryarchaeota, were observed in contaminated samples. Redundancy analysis indicated that increased relative abundances of the phyla Chloroflexi, Firmicutes, and Euryarchaeota correlated with the presence of contamination. Shifts in the chemical composition of diesel constituents across the site and the abundance of specific operational taxonomic units (OTUs; defined using a 97% sequence identity threshold) in contaminated samples together suggest that natural attenuation of contamination has occurred. OTUs with sequence similarity to strictly anaerobic Anaerolineae within the Chloroflexi, as well as to Methanosaeta of the phylum Euryarchaeota, were detected. Anaerolineae and Methanosaeta are known to be associated with anaerobic degradation of oil-related compounds; therefore, their presence suggests that natural attenuation has occurred under anoxic conditions. This research underscores the usefulness of next-generation sequencing techniques both to understand the ecological impact of contamination and to identify potential molecular proxies for detection of natural attenuation. PMID:23144139

Maphosa, Farai; Morillo, Jose A.; Abu Al-Soud, Waleed; Langenhoff, Alette A. M.; Grotenhuis, Tim; Rijnaarts, Huub H. M.; Smidt, Hauke

2013-01-01

101

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

PubMed

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

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

2011-07-01

102

Diamond Shaving of Contaminated Concrete Surfaces  

SciTech Connect

Decommissioning and decontamination of existing facilities presents technological challenges. One major challenge is the removal of surface contamination from concrete floors and walls while eliminating the spread of contamination and volumetric reduction of the waste stream. Numerous methods have been tried with a varying degree of success. Recent technology has made this goal achievable and has been used successfully. This new technology is the Diamond Floor Shaver and Diamond Wall shaver. The Diamond Floor Shaver is a self-propelled, walk behind machine that literally shaves the contaminated concrete surface to specified depths. This is accomplished by using a patented system of 100 dry cutting diamond blades with offset diamond segments that interlock to provide complete shaving of the concrete surface. Grooves are eliminated which allows for a direct frisk reading to analyze results. When attached to an appropriate size vacuum, the dust produced is 100% contained. Dust is collected in drums ready for disposition and disposal. The waste produced in shaving 7,500 square feet at 1/8 inch thickness would fill a single 55 gallon drum. Production is dependent on depth of shaving but averages 100 square feet per hour. The wall shaver uses the same patented diamond drum and blades but is hydraulically driven and is deployed using a robotic arm allowing its operation to be to totally remote. It can reach ceilings as high as 20 feet. Numerous small projects were successfully completed using this technology. Large scale deployment came in 2003. Bluegrass, in conjunction with Bartlett Services, deployed this technology to support decontamination activities for closing of the Rocky Flats nuclear weapons site. Up to six floor shavers and one wall shaver were deployed in buildings B371 and B374. These buildings had up to one half-inch, fixed plutonium and beryllium contamination. Hundred-thousands of square feet of floors and walls were shaved successfully to depths of up to one half inch. Decontamination efforts were so successful the balance of the buildings could be demolished using conventional methods. The shavers helped keep the project on schedule while the vacuum system eliminated the potential for contaminants becoming airborne.

Mullen, Lisa K. [Bluegrass Concrete Cutting Inc., 107 Mildred Street PO Box 427, Greenville, Alabama 36037 (United States)

2008-01-15

103

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

PubMed

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

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

2014-01-01

104

Faecal contamination of greywater and associated microbial risks  

Microsoft Academic Search

The faecal contamination of greywater in a local treatment system at Vibyåsen, north of Stockholm, Sweden was quantified using faecal indicator bacteria and chemical biomarkers. Bacterial indicator densities overestimated the faecal load by 100–1000-fold when compared to chemical biomarkers. Based on measured levels of coprostanol, the faecal load was estimated to be 0.04gperson?1day?1. Prevalence of pathogens in the population and

Jakob Ottoson; Thor Axel Stenström

2003-01-01

105

Microbial treatment of sulfur-contaminated industrial wastes.  

PubMed

The present study evaluated the microbial removal of sulfur from a solid industrial waste in liquid culture under laboratory conditions. The study involved the use of two bacteria Acidithiobacillus ferrooxidans ATCC 53987 and Acidithiobacillus thiooxidans AZCT-M125-5 isolated from a Mexican soil. Experimentation for industrial waste biotreatment was done in liquid culture using 125-mL Erlenmeyer flasks containing 30 mL Starkey modified culture medium and incubated at 30°C during 7 days. The industrial waste was added at different pulp densities (8.25-100% w/v) corresponding to different sulfur contents from 0.7 to 8.63% (w/w). Sulfur-oxidizing activity of the strain AZCT-M125-5 produced 281 and 262 mg/g of sulfate and a sulfur removal of 60% and 45.7% when the pulp density was set at 8.25 and 16.5% (w/v), respectively. In comparison, the strain A. ferrooxidans ATCC 53987 showed a lower sulfur-oxidizing activity with a sulfate production of 25.6 and 12.7 mg/g and a sulfur removal of 6% and 2.5% at the same pulp densities, respectively. Microbial growth was limited by pulp densities higher than 25% (w/v) of industrial waste with minimal sulfur-oxidizing activity and sulfur removal. The rate of sulfur removal for Acidithiobacillus thioxidans AZCT-M125-5 and Acidithiobacillus ferrooxidans ATCC 53987 was 0.185 and 0.0159 mg S g(-1) h(-1) with a pulp density of 16.5% (w/v), respectively. This study demonstrated that Acidithiobacillus thiooxidans AZCT-M125-5 possesses a high sulfur-oxidizing activity, even at high sulfur concentration, which allows the treatment of hazardous materials. PMID:24171423

Gómez-Ramírez, Marlenne; Zarco-Tovar, Karina; Aburto, Jorge; de León, Roberto García; Rojas-Avelizapa, Norma G

2014-01-01

106

Microbial Transformation of Polycyclic Aromatic Hydrocarbons in Pristine and Petroleum-Contaminated Sediments †  

PubMed Central

To determine rates of microbial transformation of polycyclic aromatic hydrocarbons (PAH) in freshwater sediments, 14C-labeled PAH were incubated with samples from both pristine and petroleum-contaminated streams. Evolved 14CO2 was trapped in KOH, unaltered PAH and polar metabolic intermediate fractions were quantitated after sediment extraction and column chromatography, and bound cellular 14C was measured in sediment residues. Large fractions of 14C were incorporated into microbial cellular material; therefore, measurement of rates of 14CO2 evolution alone would seriously underestimate transformation rates of [14C]naphthalene and [14C]anthracene. PAH compound turnover times in petroleum-contaminated sediment increased from 7.1 h for naphthalene to 400 h for anthracene, 10,000 h for benz(a)anthracene, and more than 30,000 h for benz(a)pyrene. Turnover times in uncontaminated stream sediment were 10 to 400 times greater than in contaminated samples, while absolute rates of PAH transformation (micrograms of PAH per gram of sediment per hour) were 3,000 to 125,000 times greater in contaminated sediment. The data indicate that four- and five-ring PAH compounds, several of which are carcinogenic, may persist even in sediments that have received chronic PAH inputs and that support microbial populations capable of transforming two- and three-ring PAH compounds. PMID:16345270

Herbes, S. E.; Schwall, L. R.

1978-01-01

107

Molecular Tools to Monitor Microbial Contaminants During Long-Term Exploration Class Missions  

NASA Astrophysics Data System (ADS)

Microbial contaminants will inevitably accompany a human crew in our adventures into space. Humans constantly shed large numbers of microorganisms into the environment, and during spaceflight some normally benign microbes may become pathogenic. Concerns about microbial disease during Exploration Class human space missions are particularly important in light of the clinically significant changes that the immune system undergoes during spaceflight. Additionally, increased microbial burdens on closed air and water systems may lead to disease and become dangerous sources of contamination for replacement crews. These microbes might also become a serious threat to regenerative life support systems. The development of a robust system to detect, identify and monitor these contaminants i therefore critical. Wes are currently developing a monitoring system that employs 16S ribosomal RNA sequence information to identify bacterial contaminants at the genus and species level. Despite extensive secondary structure, a large number of regions on the 16S rRNA molecule have been successfully targeted. Probes specific for certain groups, such as "all bacteria", "Gram positives", "Gram negatives", and "enterics", as well as some targeting specific genera and species have been designed and optimized. A set of working probes is now being tested in a variety of solution assays that exploit new and exciting technologies such as molecular beacons and DNA microarrays.

Larios-Sanz, M.; Kourentzi, K.; Willson, R.; Pierson, D.; Fox, G.

108

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

USGS Publications Warehouse

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.

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

1998-01-01

109

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

PubMed

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

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

2014-08-19

110

Ion Beam Removal of Surface Contamination in Genesis Samples  

NASA Astrophysics Data System (ADS)

Surface contamination of Genesis samples limits our ability to accurately measure solar wind fluences. We show using AFM, TXRF, interferometry and RIMS depth profiling that cluster ion sputtering can successfully remove such contamination.

King, B. V.; Veryovkin, I. V.; Zinovev, A. V.; Tripa, C. E.; Pellin, M. J.; Toyoda, N.; Yamada, I.; Schmeling, M.

2010-03-01

111

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

PubMed

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

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

2014-01-01

112

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

113

Microbial contamination of suction tubes attached to suction instruments and preventive methods.  

PubMed

We investigated the microbial contamination of suction tubes attached to wall-type suction instruments. Microbial contamination of suction tubes used for endoscopy or sputum suction in hospital wards was examined before and after their disinfection. In addition, disinfection and washing methods for suction tubes were evaluated. Suction tubes (n=33) before disinfection were contaminated with 10(2)-10(8) colony-forming units (cfu)/tube. The main contaminants were Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia. The suction tubes were disinfected with sodium hypochlorite (n=11) or hot water (n=11), or by an automatic tube cleaner (n=11). After 2-h immersion in 0.1% (1,000 ppm) sodium hypochlorite, 10(3)-10(7) cfu/tube of bacteria were detected in all 11 tubes examined. After washing in hot running water (65 degrees C), 10(3)-10(7) cfu/tube were detected in 3 of the 11 examined tubes. The bacteria detected in the suction tubes after disinfection with sodium hypochlorite or hot water were P. aeruginosa, A. baumannii, and S. maltophilia. On the other hand, after washing with warm water (40 degrees C) using the automatic tube cleaner, contamination was found to be <20 cfu/tube (lower detection limit, 20 cfu/tube) in all 11 tubes examined. These results suggest the usefulness of washing with automatic tube cleaners. PMID:20332576

Yorioka, Katsuhiro; Oie, Shigeharu; Kamiya, Akira

2010-03-01

114

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

115

New methods for microbial contamination monitoring: an experiment on board the MIR orbital station.  

PubMed

Experiment T2, carried out during the Euromir'95 mission, was an important step toward innovative methods for spacecraft microbial contamination monitoring. A new standard sampling technique permitted samples to be analysed by different means. On board, two analysis methods were tested in parallel: Bioluminescence and Miniculture. In turn, downloaded samples are being analysed by polymerase chain reaction (PCR), a powerful and promising method for the rapid detection, identification and quantification of pathogens and biofouling agents in closed manned habitats. PMID:11540769

Guarnieri, V; Gaia, E; Battocchio, L; Pitzurra, M; Savino, A; Pasquarella, C; Vago, T; Cotronei, V

1997-01-01

116

Geophysical Signatures of Microbial Activity at Hydrocarbon Contaminated Sites: A Review  

Microsoft Academic Search

Microorganisms participate in a variety of geologic processes that alter the chemical and physical properties of their environment.\\u000a Understanding the geophysical signatures of microbial activity in the environment has resulted in the development of a new\\u000a sub-discipline in geophysics called “biogeophysics”. This review focuses primarily on literature pertaining to biogeophysical\\u000a signatures of sites contaminated by light non-aqueous phase liquids (LNAPL),

Estella A. Atekwana; Eliot A. Atekwana

2010-01-01

117

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

Microsoft Academic Search

The aim of the research was to analyse the influence of a topsoil of pyroclastic origin on microbial contamination of groundwater\\u000a in a carbonate aquifer and verify the reliability of thermotolerant coliforms and fecal enterococci as bacterial indicators.\\u000a The research was carried out through hydrogeological and microbiological monitoring at an experimental field site in Italy\\u000a during two hydrologic years and

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

2008-01-01

118

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

Microsoft Academic Search

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

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

1997-01-01

119

Microbial Communities in Contaminated Sediments, Associated with Bioremediation of Uranium to Submicromolar Levels  

Microsoft Academic Search

Microbial enumeration, S rRNA gene clone libraries, and chemical analysis were used to evaluate the in situ biological reduction and immobilization of uranium(VI) in a long-term experiment (more than 2 years) conducted at a highly uranium-contaminated site (up to 60 mg\\/liter and 800 mg\\/kg solids) of the U.S. Department of Energy in Oak Ridge, TN. Bioreduction was achieved by conditioning

Erick Cardenas; Wei-Min Wu; Mary Beth Leigh; Jack M Carley; Sue L Carroll; Terry Gentry; Jian Luo; David B Watson; Matthew Ginder-Vogel; Peter K. Kitanidis; Philip M. Jardine; Jizhong Zhou; Craig S. Criddle; Terence L. Marsh; James M. Tiedje

2008-01-01

120

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

PubMed Central

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

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

121

Microbial contamination of peripheral blood and bone marrow hematopoietic cell products and environmental contamination in a stem cell bank: a single-center report.  

PubMed

Hematopoietic stem cells (HSC) derived from peripheral blood (PB) and bone marrow (BM) are frequently used for autologous and allogenic transplantations. Establishing quality control at appropriate steps of the stem cell preparation process is crucial for a successful transplantation. Microbial contamination of haematopoietic stem cells is rare but could cause a potentially mortal complication of a stem cells transplantation. We investigated the microbiological contamination of PB (291 donations) and BM (39 donations) products. Microbial cultures of 330 donations between January 2012 and June 2013 were retrospectively analyzed after the collection and preparation steps. The microbiological analysis was performed with an automated system. Hematopoietic stem cells were processed in a closed system. Additionally, in this report the environment of the working areas of stem cell preparation was monitored. We analyzed microbial contamination of the air in a class I laminar air flow clean bench at the time of preparation and in the laboratory once per month. We reported 9 (2.73%) contaminated HSC products. The most frequent bacteria isolated from PB and BM products were Bacillus species. Coagulase-negative staphylococci and Micrococcus species were the most frequent micro-organisms detected in the air microbial control. Microbial control results are necessary for the safety of hematopoietic stem cell products transplantation. Microbial control of hematopoietic stem cell products enables an early contamination detection and allows for knowledgeable decision making concerning either discarding the contaminated product or introducing an efficient antibiotic therapy. Each step of cell processing may cause a bacterial contamination. A minimum of manipulation steps is crucial for increasing the microbial purity of the transplant material. Also, the air contamination control is essential to ensure the highest quality standards of HSC products preparation. PMID:25380939

Kozlowska-Skrzypczak, M; Bembnista, E; Kubiak, A; Matuszak, P; Schneider, A; Komarnicki, M

2014-01-01

122

Microbial communities along biogeochemical gradients in a hydrocarbon-contaminated aquifer.  

PubMed

Micro-organisms are known to degrade a wide range of toxic substances. How the environment shapes microbial communities in polluted ecosystems and thus influences degradation capabilities is not yet fully understood. In this study, we investigated microbial communities in a highly complex environment: the capillary fringe and subjacent sediments in a hydrocarbon-contaminated aquifer. Sixty sediment sections were analysed using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting, cloning and sequencing of bacterial and archaeal 16S rRNA genes, complemented by chemical analyses of petroleum hydrocarbons, methane, oxygen and alternative terminal electron acceptors. Multivariate statistics revealed concentrations of contaminants and the position of the water table as significant factors shaping the microbial community composition. Micro-organisms with highest T-RFLP abundances were related to sulphate reducers belonging to the genus Desulfosporosinus, fermenting bacteria of the genera Sedimentibacter and Smithella, and aerobic hydrocarbon degraders of the genus Acidovorax. Furthermore, the acetoclastic methanogens Methanosaeta, and hydrogenotrophic methanogens Methanocella and Methanoregula were detected. Whereas sulphate and sulphate reducers prevail at the contamination source, the detection of methane, fermenting bacteria and methanogenic archaea further downstream points towards syntrophic hydrocarbon degradation. PMID:23809669

Tischer, Karolin; Kleinsteuber, Sabine; Schleinitz, Kathleen M; Fetzer, Ingo; Spott, Oliver; Stange, Florian; Lohse, Ute; Franz, Janett; Neumann, Franziska; Gerling, Sarah; Schmidt, Christian; Hasselwander, Eyk; Harms, Hauke; Wendeberg, Annelie

2013-09-01

123

Widespread potential for microbial MTBE degradation in surface-water sediments  

USGS Publications Warehouse

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.

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

2001-01-01

124

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

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

125

Microbial Community Acquisition of Nutrients from Mineral Surfaces. Final Report  

SciTech Connect

Minerals and microbes undergo complex interactions in nature that impact broad aspects of near-surface Earth chemistry. Our primary objective in this project was to gain insight into how microbial species and communities acquire critical but tightly held nutrients residing on or within minerals common in rocks and soils, and to quantitatively study related microbe-mineral interactions including cell adhesion, electron transfer, and siderophore-mineral interaction processes.

Hochella, M. F.

2003-06-03

126

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

PubMed

For dairy products that are consumed fresh, contamination by spoilage microorganisms and pathogens from the environment is a major concern. Contamination has been associated with a number of outbreaks of foodborne illnesses; however, consistent data pertaining to the microbial safety of whey cheeses specifically have not been reported. Hence, the goals of this research effort were (i) to manufacture a probiotic whey cheese with Bifidobacterium animalis and Lactobacillus casei and (ii) to assess the antimicrobial activity of these probiotics against a set of foodborne pathogens (Listeria innocua, Salmonella Enteritidis, and Staphylococcus aureus) and food spoilage microorganisms (Pseudomonas aeruginosa and Escherichia coli). Three ranges of these microbial contaminants were used for inoculation of cheeses: 10(3) to 10(4), 10(4) to 10(6), and 10(6) to 10(8) CFU/g. Inoculation in plain culture medium served as a control. The inhibition produced by the probiotics was calculated, and the major effect was found to be bacteriostatic. In specific cases, full inhibition was observed, i.e., by B. animalis against P. aeruginosa and by L. casei against Salmonella Enteritidis and L. innocua. Conversely, the least inhibition was detected for L. casei against P. aeruginosa. Our results suggest that use of these probiotic strains can extend the shelf life of whey cheeses and make them safer by delaying or preventing growth of common contaminant bacteria. PMID:21740724

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

2011-07-01

127

Quantitative analysis of microbial contamination in private drinking water supply systems.  

PubMed

Over one million households rely on private water supplies (e.g. well, spring, cistern) in the Commonwealth of Virginia, USA. The present study tested 538 private wells and springs in 20 Virginia counties for total coliforms (TCs) and Escherichia coli along with a suite of chemical contaminants. A logistic regression analysis was used to investigate potential correlations between TC contamination and chemical parameters (e.g. NO3(-), turbidity), as well as homeowner-provided survey data describing system characteristics and perceived water quality. Of the 538 samples collected, 41% (n = 221) were positive for TCs and 10% (n = 53) for E. coli. Chemical parameters were not statistically predictive of microbial contamination. Well depth, water treatment, and farm location proximate to the water supply were factors in a regression model that predicted presence/absence of TCs with 74% accuracy. Microbial and chemical source tracking techniques (Bacteroides gene Bac32F and HF183 detection via polymerase chain reaction and optical brightener detection via fluorometry) identified four samples as likely contaminated with human wastewater. PMID:23708572

Allevi, Richard P; Krometis, Leigh-Anne H; Hagedorn, Charles; Benham, Brian; Lawrence, Annie H; Ling, Erin J; Ziegler, Peter E

2013-06-01

128

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

PubMed

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

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

2014-10-01

129

The surface stress theory of microbial morphogenesis.  

PubMed

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

Koch, A L

1983-01-01

130

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

PubMed

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

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

2013-01-01

131

Biodegradation during contaminant transport in porous media: 4. Impact of microbial lag and bacterial cell growth  

NASA Astrophysics Data System (ADS)

Miscible-displacement experiments were conducted to examine the impact of microbial lag and bacterial cell growth on the transport of salicylate, a model hydrocarbon compound. The impacts of these processes were examined separately, as well as jointly, to determine their relative effects on biodegradation dynamics. For each experiment, a column was packed with porous medium that was first inoculated with bacteria that contained the NAH plasmid encoding genes for the degradation of naphthalene and salicylate, and then subjected to a step input of salicylate solution. The transport behavior of salicylate was non-steady for all cases examined, and was clearly influenced by a delay (lag) in the onset of biodegradation. This microbial lag, which was consistent with the results of batch experiments, is attributed to the induction and synthesis of the enzymes required for biodegradation of salicylate. The effect of microbial lag on salicylate transport was eliminated by exposing the column to two successive pulses of salicylate, thereby allowing the cells to acclimate to the carbon source during the first pulse. Elimination of microbial lag effects allowed the impact of bacterial growth on salicylate transport to be quantified, which was accomplished by determining a cell mass balance. Conversely, the impact of microbial lag was further investigated by performing a similar double-pulse experiment under no-growth conditions. Significant cell elution was observed and quantified for all conditions/systems. The results of these experiments allowed us to differentiate the effects associated with microbial lag and growth, two coupled processes whose impacts on the biodegradation and transport of contaminants can be difficult to distinguish.

Sandrin, Susannah K.; Jordan, Fiona L.; Maier, Raina M.; Brusseau, Mark L.

2001-08-01

132

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

133

Microbial contamination associated with consumption and the growth in plastic bottled beverage.  

PubMed

Plastic bottles enable the storage of unfinished beverages, and most of microbial contamination has occurred in the unfinished beverage that was left. Therefore, we investigated microorganisms in various beverages contaminated by pouring and drinking directly by mouth from the bottle, and analyzed the growth of microorganisms in the beverages at room temperature. In the pouring test, microbial growth was detected in 60 of 320 samples, and 13 bacterial strains, 49 mold strains, and 8 yeast strains were isolated. Molds including Cladosporium spp., Tramets spp., Bjerkandera spp., and Penicillium spp. accounted for the majority of isolated microorganisms. In the drinking test, microbial growth was detected in 181 of 352 samples, and 225 bacterial strains, 27 mold strains and 77 yeast strains were isolated. Bacteria including Streptococcus spp. such as S. salivarius and Staphylococcus spp. such as S. aureus accounted for the majority of isolated microorganisms. Enterotoxin-producing S. aureus and Bacillus cereus were also isolated. The pH of the beverage influenced the growth of bacteria. The Brix values of the beverage did not correlate with the growth of microorganisms. These results revealed that various microorganisms including foodborne pathogens were able to grow in numerous types of beverages and that the storage of unfinished beverage in inappropriate condition, such as the storage at room temperature led microorganism to grow easily in beverage. Therefore, it is necessary to consume beverages as soon as possible after opening the bottle. PMID:23445421

Ohnishi, Takahiro; Goto, Keiichi; Kanda, Takashi; Kanazawa, Yuji; Ozawa, Kazuhiro; Sugiyama, Kanji; Watanabe, Maiko; Konuma, Hirotaka; Hara-Kudo, Yukiko

2013-01-01

134

Biophysical Methods for the Study of Microbial Surfaces  

PubMed Central

The challenge in studying the surface architecture of different microbial pathogens is to integrate the most current biochemical, spectroscopic, microscopic, and processing techniques. Individually these methods have insufficient sensitivity to reveal complex structures, such as branched, large, viscous polymers with a high structure hydration, size, and complexity. However, when used in combination biophysical techniques are our primary source of information for understanding polydisperse molecules and complex microbial surfaces. Biophysical methods seek to explain biological function in terms of the molecular structures and properties of specific molecules. The sizes of the molecules found in microbial surfaces vary greatly from small fatty acids and sugars to macromolecules like proteins, polysaccharides, and pigments, such as melanin. These molecules, which comprise the building blocks of living organisms, assemble into cells, tissues, and whole organisms by forming complex individual structures with dimensions from 10 to 10,000?nm and larger. Biophysics is directed to determining the structure of specific biological molecules and of the larger structures into which they assemble. Some of this effort involves developing new methods, adapting old methods and building new instruments for viewing these structures. The description of biophysical properties in an experimental model where, properties such as flexibility, hydrodynamic characteristics, and size can be precisely determined is of great relevance to study the affinity of the surfaces with biologically active and inert substrates and the interaction with host molecules. Furthermore, this knowledge could establish the abilities of different molecules and their structures to differentially activate cellular responses. Recent studies in the fungal pathogen Cryptococcus neoformans have demonstrated that the physical properties of its unique polysaccharide capsule correlate with the biological functions associated with the intact capsule and the components comprising the capsule. In this review, we describe the application of biophysical techniques to study and characterize this highly hydrated and fragile fungal surface structure. PMID:22013430

Frases, Susana; Viana, Nathan B.; Casadevall, Arturo

2011-01-01

135

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

SciTech Connect

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

Cushman, J.H.; Madilyn Fletcher

2000-06-01

136

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

SciTech Connect

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.

Cushman, J.H.

2000-06-01

137

Microbial Community Responses to Organophosphate Substrate Additions in Contaminated Subsurface Sediments  

PubMed Central

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

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

138

Viability in methyl soyate of microbial contaminants from farm fuel storage tanks  

SciTech Connect

Biodiesel is a renewable, environmentally sound alternative fuel derived from vegetable oils and animal fats, Microbial contamination is a known problem with diesel fuel. The susceptibility of methyl soyate or its blends with diesel fuel to microbial growth has not been investigated. Bacillus species including two B. cereus strains were identified as problem-causing microorganisms in diesel fuel samples collected from agricultural diesel fuel storage tanks. Growth of these microorganisms was inhibited by methyl soyate. Inoculated bacteria were not viable in methyl soyate or in 20/80, 50/50, and 80/20% methyl soyate/diesel fuel blend samples after 8 weeks of storage. In contrast, bacterial counts increased significantly (P < 0.05) in both distilled water control and diesel fuel samples after 8 weeks of storage. 15 refs., 5 figs., 1 tab.

Ryu, D.; Katta, S.K.; Bullerman, L.B.; Hanna, M.A.; Gennadios, A. [Univ. of Nebraska, Lincoln, NE (United States)

1996-11-01

139

Compositions and methods to prevent microbial contamination of plant tissue culture media  

US Patent & Trademark Office Database

The present invention encompasses compositions and methods to reduce or prevent microbial growth in plant tissue culture media, comprising adding a chemical agent comprising methylchloroisothiazolinone, methylisothiazolinone, magnesium chloride and magnesium nitrate to a plant culture medium at a concentration that reduces or prevents microbial contamination of the plant tissue culture medium and that allows substantially normal germination of seeds or substantially normal growth or development of plants, plant organs, plant tissues or plant cells. The chemical agent may further comprise potassium sorbate or sodium benzoate, or both. The present invention further provides a kit for germinating plant seeds or culturing plants, plant organs, plant tissues or plant cells on a plant tissue culture medium comprising the chemical agent.

1998-05-12

140

Use of nutrient supplements to increase the microbial degradation of PAH in contaminated soils  

SciTech Connect

The microbial degradation of polycyclic aromatic hydrocarbons (PAH) is often low in soils due to unavailability of PAH and/or to conditions in the soil that are not favorable to microbial activity. As a result, successful bioremediation of PAH contaminated soils may require the addition of supplements to impact PAH availability or soil conditions. This paper reports on the addition of supplements (Triton X-100, Inopol, nutrient buffer, an organic nutrient solution, salicylic acid) on the fate of (9-{sup 14}C) phenanthrene, a model PAH, in creosote contaminated soils. Phenanthrene metabolism was assessed using a mass balance approach that accounts for metabolism of phenanthrene to CO{sub 2}, relative metabolite production, and uptake of phenanthrene into cells. Most of the supplements did not drastically alter the fate of phenanthrene in the contaminated soils. Additions of Inopol, however, increased phenanthrene mineralization, while salicylic acid decreased phenanthrene mineralization but greatly increased the production of polar and water soluble metabolites. All supplements (excluding salicylic acid and the organic nutrient solution) increased populations of heterotrophic microorganisms, as measured by plate counts. Phenanthrene degrader populations, however, were only slightly increased by additions of the nutrient buffer, as measured by the Most Probable Number assay.

Carmichael, L.M.; Pfaender, F.K. [Univ. of North Carolina, Chapel Hill, NC (United States)

1994-12-31

141

Microbial risks associated with exposure to pathogens in contaminated urban flood water.  

PubMed

Urban flood incidents induced by heavy rainfall in many cases entail flooding of combined sewer systems. These flood waters are likely to be contaminated and may pose potential health risks to citizens exposed to pathogens in these waters. The purpose of this study was to evaluate the microbial risk associated with sewer flooding incidents. Concentrations of Escherichia coli, intestinal enterococci and Campylobacter were measured in samples from 3 sewer flooding incidents. The results indicate faecal contamination: faecal indicator organism concentrations were similar to those found in crude sewage under high-flow conditions and Campylobacter was detected in all samples. Due to infrequent occurrence of such incidents only a small number of samples could be collected; additional data were collected from controlled flooding experiments and analyses of samples from combined sewers. The results were used for a screening-level quantitative microbial risk assessment (QMRA). Calculated annual risks values vary from 5 x 10(-6) for Cryptosporidium assuming a low exposure scenario to 0.03 for Giardia assuming a high exposure scenario. The results of this screening-level risk assessment justify further research and data collection to allow more reliable quantitative assessment of health risks related to contaminated urban flood waters. PMID:20227742

ten Veldhuis, J A E; Clemens, F H L R; Sterk, G; Berends, B R

2010-05-01

142

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...

143

Microbial role in the failure of natural attenuation of chromium(VI) in long-term tannery waste contaminated soil  

Microsoft Academic Search

Bioremediation of Cr(VI) in long-term contaminated soil environment has not been very successful due to the known reoxidation of Cr(III) to Cr(VI). Microbial role on the presence of Cr(VI) in soil samples from a long-term tannery waste contaminated site, even 25 years after cessation of waste disposal was examined. The contaminated soil, unamended or amended with 6.6% (w\\/w) cow manure,

N. Sethunathan; M. Megharaj; L. Smith; S. P. B. Kamaludeen; S. Avudainayagam; R. Naidu

2005-01-01

144

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

NASA Astrophysics Data System (ADS)

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.

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

2003-08-01

145

A multivariate statistical approach to spatial representation of groundwater contamination using hydrochemistry and microbial community profiles.  

PubMed

Managers of landfill sites are faced with enormous challenges when attempting to detect and delineate leachate plumes with a limited number of monitoring wells, assess spatial and temporal trends for hundreds of contaminants, and design long-term monitoring (LTM) strategies. Subsurface microbial ecology is a unique source of data that has been historically underutilized in LTM groundwater designs. This paper provides a methodology for utilizing qualitative and quantitative information (specifically, multiple water quality measurements and genome-based data) from a landfill leachate contaminated aquifer in Banisveld, The Netherlands, to improve the estimation of parameters of concern. We used a principal component analysis (PCA) to reduce nonindependent hydrochemistry data, Bacteria and Archaea community profiles from 16S rDNA denaturing gradient gel electrophoresis (DGGE), into six statistically independent variables, representing the majority of the original dataset variances. The PCA scores grouped samples based on the degree or class of contamination and were similar over considerable horizontal distances. Incorporation of the principal component scores with traditional subsurface information using cokriging improved the understanding of the contaminated area by reducing error variances and increasing detection efficiency. Combining these multiple types of data (e.g., genome-based information, hydrochemistry, borings) may be extremely useful at landfill or other LTM sites for designing cost-effective strategies to detect and monitor contaminants. PMID:16245827

Mouser, Paula J; Rizzo, Donna M; Röling, Wilfred F M; Van Breukelen, Boris M

2005-10-01

146

Changes in developing plant microbial community structure as affected by contaminated water.  

PubMed

The effects of sand and clay soils and water contaminated by Escherichia coli O157:H7 on the development of rhizosphere and phyllosphere microbial communities were analyzed to determine the influence of plant age on microbial community structure and composition. Community bacterial nucleic acids were extracted from lettuce rhizosphere and phyllosphere samples at different stages of plant development after the soils were irrigated with water contaminated with E. coli O157:H7 at planting and 15 days after planting. PCR was used to amplify 16S ribosomal RNA (rRNA) for total bacterial community composition and the products were subjected to denaturing gradient gel electrophoresis (DGGE). Prominent DGGE bands were excised and sequenced to gain insight into the identities of predominant bacterial populations. The majority of DGGE band sequences were related to bacterial genera previously associated with the rhizosphere and phyllosphere, such as Pseudomonas, Acidobacterium, Bacillus and Agrobacterium. The PCR-DGGE patterns observed for rhizosphere samples were more complex than those obtained from the bulk soil and the phyllosphere. The Shannon index of diversity (H) was used to determine the complexity of the DGGE bands from the phyllosphere, rhizosphere and the bulk soils at different growth stages. A higher diversity was observed in the clay soil than sandy soil during the first week. Few changes in diversity were observed after the first week. The results show that microbial community development in lettuce may take about 7-12 days and this may be the most likely period for maximum pathogen contamination in plants. PMID:19712407

Ibekwe, A M; Grieve, C M

2004-05-01

147

Photochemically induced surface contamination: Mechanisms and effects  

SciTech Connect

Spacecraft function is a hostile environment of sunlight, charged particles, micrometeoroids and debris, and their own self-induced contamination environment. Contamination can occur during fabrication and ground processing, or by very long term outgassing and transport processes on orbit. One of the most deleterious effects of contaminant films is that they increase the solar absorptance of optics, such as thermal control mirrors and solar cell cover slips. This paper will discuss the role of vacuum ultraviolet induced photochemistry in the deposition of contaminant films during the multi-year life of a spacecraft. Laboratory and spaceflight measurements leading to a one-photon `Langmuir` type model for the deposition mechanism will be presented. Measurements of visible and ultraviolet optical properties of photodeposited films will be described. The implications of these processes for terrestrial optical systems, including a case history of similar effects in an ultraviolet laser system studied in this laboratory will be discussed.

Arnold, G.S.; Luey, K.T. [Aerospace Corp, El Segundo, CA (United States)

1996-12-31

148

High surface area electrode for high efficient microbial electrosynthesis  

NASA Astrophysics Data System (ADS)

Microbial electrosynthesis, a process in which microorganisms directly accept electrons from an electrode to convert carbon dioxide and water into multi carbon organic compounds, affords a novel route for the generation of valuable products from electricity or even wastewater. The surface area of the electrode is critical for high production. A biocompatible, highly conductive, three-dimensional cathode was fabricated from a carbon nanotube textile composite to support the microorganism to produce acetate from carbon dioxide. The high surface area and macroscale porous structure of the intertwined CNT coated textile ?bers provides easy microbe access. The production of acetate using this cathode is 5 fold larger than that using a planar graphite electrode with the same volume. Nickel-nanowire-modified carbon electrodes, fabricated by microwave welding, increased the surface area greatly, were able to absorb more bacteria and showed a 1.5 fold increase in performance

Nie, Huarong; Cui, Mengmeng; Lu, Haiyun; Zhang, Tian; Russell, Thomas; Lovley, Derek

2012-02-01

149

Screening of molecular repertoires by microbial surface display.  

PubMed

A multitude of systems for the presentation of foreign peptides or proteins on the surface of microorganisms has been developed within the past two decades. However, the majority of the bacterial surface display systems are devoted to the presentation of heterologous antigens to the immune system (vaccine generation). Bacteria are the preferable hosts for the generation of vast genetic repertoires, and their genetic manipulation and cultivation is easy. As a consequence, they provide promising systems for large-scale functional screenings, e.g. for enzyme activity or protein-protein interactions. This review will focus on examples of microbial surface display used for the screening of combinatorial repertoires. Further, we discuss future opportunities and promising candidate proteins not yet employed for that task. PMID:15777176

Jostock, Thomas; Dübel, Stefan

2005-03-01

150

The Effects of Microbial Surfaces on Mineral Trapping  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

151

Canine scent detection and microbial source tracking of human waste contamination in storm drains.  

PubMed

Human fecal contamination of surface waters and drains is difficult to diagnose. DNA-based and chemical analyses of water samples can be used to specifically quantify human waste contamination, but their expense precludes routine use. We evaluated canine scent tracking, using two dogs trained to respond to the scent of municipal wastewater, as a field approach for surveying human fecal contamination. Fecal indicator bacteria, as well as DNA-based and chemical markers of human waste, were analyzed in waters sampled from canine scent-evaluated sites (urban storm drains and creeks). In the field, the dogs responded positively (70% and 100%) at sites for which sampled waters were then confirmed as contaminated with human waste. When both dogs indicated a negative response, human waste markers were absent. Overall, canine scent tracking appears useful for prioritizing sampling sites for which DNA-based and similarly expensive assays can confirm and quantify human waste contamination. PMID:25109201

Van De Werfhorst, Laurie C; Murray, Jill L S; Reynolds, Scott; Reynolds, Karen; Holden, Patricia A

2014-06-01

152

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

SciTech Connect

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.

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

153

Factors That Influence Microbial Contamination of Fluids Associated with Hemodialysis Machines  

PubMed Central

Studies were conducted on the microbiological quality of fluids associated with different types of dialysis systems located in six dialysis centers and 14 homes. Included were (i) single-pass systems employing either parallel flow (Kiil or Gambro) or capillary cartridge dialyzers and (ii) recirculating single-pass and batch recirculating systems using coil dialyzers. Microbiological assays were performed on the water used to prepare dialysis fluid, the concentrated dialysate, and either pre- and postdialyzer dialysate (single-pass systems) or the dialysate contained in storage reservoirs and recirculating cannisters (recirculating systems). The levels of microbial contamination consisting of gram-negative bacteria were directly related to the type of dialysis system, method of water treatment, distribution system, and in some instances, the type of dialyzer. Recirculating single-pass and batch recirculating systems consistently contained significantly higher levels of contamination than single-pass systems. These results were directly related to the design of recirculating systems which permits carbon- and nitrogen-containing waste products dialyzed from the patient to accumulate, be used as nutrients by microorganisms, and subsequently allow for 2- to 4-log increases in contamination levels during a dialysis treatment. In contrast, levels of contamination in single-pass machines were related more to the quality of the water used to prepare dialysis fluid and the adequacy of cleaning and disinfection procedures than to the design of the system. Images PMID:4216291

Favero, Martin S.; Carson, Loretta A.; Bond, Walter W.; Petersen, Norman J.

1974-01-01

154

Phylogenetic Microarray Analysis of a Microbial Community Performing Reductive Dechlorination at a TCE-contaminated Site  

PubMed Central

A high-density phylogenetic microarray (PhyloChip) was applied to track bacterial and archaeal populations through different phases of remediation at Ft. Lewis, WA, a trichloroethene (TCE)-contaminated groundwater site. Biostimulation with whey, and bioaugmentation with a Dehalococcoides-containing enrichment culture were strategies implemented to enhance dechlorination. As a measure of species richness, over 1300 operational taxonomic units (OTUs) were detected in DNA from groundwater samples extracted during different stages of treatment and in the bioaugmentation culture. In order to determine active members within the community, 16S rRNA from samples were analyzed by microarray and ~600 OTUs identified. A cDNA clone library of the expressed 16S rRNA corroborated the observed diversity and activity of some of the phyla. Principle component analysis of the treatment plot samples revealed that the microbial populations were constantly changing during the course of the study. Dynamic analysis of the archaeal population showed significant increases in methanogens at the later stages of treatment that correlated with increases in methane concentrations of over two orders of magnitude. Overall, the PhyloChip analyses in this study have provided insights into the microbial ecology and population dynamics at the TCE-contaminated field site useful for understanding the in situ reductive dechlorination processes. PMID:22091783

Lee, Patrick K. H.; Warnecke, F.; Brodie, Eoin L.; Macbeth, Tamzen W.; Conrad, Mark E.; Andersen, Gary L.; Alvarez-Cohen, Lisa

2012-01-01

155

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

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

156

Total effective dose equivalent associated with fixed uranium surface contamination  

SciTech Connect

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.

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

1997-04-01

157

Identification of contaminant type in surface electromyography (EMG) signals.  

PubMed

The ability to recognize various forms of contaminants in surface electromyography (EMG) signals and to ascertain the overall quality of such signals is important in many EMG-enabled rehabilitation systems. In this paper, new methods for the automatic identification of commonly occurring contaminant types in surface EMG signals are presented. Such methods are advantageous because the contaminant type is typically not known in advance. The presented approach uses support vector machines as the main classification system. Both simulated and real EMG signals are used to assess the performance of the methods. The contaminants considered include: 1) electrocardiogram interference; 2) motion artifact; 3) power line interference; 4) amplifier saturation; and 5) additive white Gaussian noise. Results show that the contaminants can readily be distinguished at lower signal to noise ratios, with a growing degree of confusion at higher signal to noise ratios, where their effects on signal quality are less significant. PMID:24760926

McCool, Paul; Fraser, Graham D; Chan, Adrian D C; Petropoulakis, Lykourgos; Soraghan, John J

2014-07-01

158

Review Of Contamination Detection On Patterned Surfaces  

NASA Astrophysics Data System (ADS)

Because particulate contamination is the largest yield detractor in semiconductor fabrication, a support technology is evolving for inspecting product (patterned) wafers to identify sources of contamination. We will describe a variety of optical phenomena that are used to detect the presence of particles and some of their performance limitations. The Lloyd's mirror configuration can be used in a coincidence geometry to suppress the pattern signals; we will show performance data from a prototype of such a system. Most of the techniques we will describe rely on the particles protruding above the surrounding pattern. There are two dominant limitations to this approach. One limitation are the classes of pattern features that will be incorrectly identified as particles. The other is that semiconductor devices are becoming increasingly sensitive to particles smaller than the vertical pattern height.

Batchelder, J. Samuel

1987-09-01

159

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

PubMed Central

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

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

2014-01-01

160

Radon induced surface contaminations in low background experiments  

SciTech Connect

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.

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

161

Subsurface characterization of groundwater contaminated by landfill leachate using microbial community profile data and a nonparametric decision-making process  

NASA Astrophysics Data System (ADS)

Microbial biodiversity in groundwater and soil presents a unique opportunity for improving characterization and monitoring at sites with multiple contaminants, yet few computational methods use or incorporate these data because of their high dimensionality and variability. We present a systematic, nonparametric decision-making methodology to help characterize a water quality gradient in leachate-contaminated groundwater using only microbiological data for input. The data-driven methodology is based on clustering a set of molecular genetic-based microbial community profiles. Microbes were sampled from groundwater monitoring wells located within and around an aquifer contaminated with landfill leachate. We modified a self-organizing map (SOM) to weight the input variables by their relative importance and provide statistical guidance for classifying sample similarities. The methodology includes the following steps: (1) preprocessing the microbial data into a smaller number of independent variables using principal component analysis, (2) clustering the resulting principal component (PC) scores using a modified SOM capable of weighting the input PC scores by the percent variance explained by each score, and (3) using a nonparametric statistic to guide selection of appropriate groupings for management purposes. In this landfill leachate application, the weighted SOM assembles the microbial community data from monitoring wells into groupings believed to represent a gradient of site contamination that could aid in characterization and long-term monitoring decisions. Groupings based solely on microbial classifications are consistent with classifications of water quality from hydrochemical information. These microbial community profile data and improved decision-making strategy compliment traditional chemical groundwater analyses for delineating spatial zones of groundwater contamination.

Pearce, Andrea R.; Rizzo, Donna M.; Mouser, Paula J.

2011-06-01

162

Evaluation of the role of environmental contamination in the microbial degradation of polyaromatic hydrocarbons  

SciTech Connect

Studies were undertaken to determine the effect of environmental contamination upon the potential for degradation of polyaromatic hydrocarbons (PAH) by the microbial populations in freshwater sediments. Naphthalene (NAP), phenanthrene (PHE), and benzo(a)pyrene(BP) were employed as substrates for PAH biodegradation. Biodegradation was assessed by mineralization of the /sup 14/C-PAH substrates incubated in sediment slurries. Mineralization rate constants and substrate turnover times were calculated for PAH mineralization studies. Sediment microcosms treated with individual, unlabeled PAH or a synthetic oil (SO) were sampled for the mineralization assay after various periods of acclimation. NAP and PHE treatments enhanced PAH mineralization rates while BP was inhibitory. The SO treatment caused a substantial enhancement of PAH mineralization rates. A PAH-degrading bacterial population added to various sediment systems did not significantly enhance PAH mineralizaion rates. Studies with natural sediment samples also indicated that previous environmental contamination tends to enhance the potential for PAH biodegradation. Studies indicated PAH mineralization in sediments was related to the length of incubation time, temperature, molecular size of the substrate and prior exposure to PAH or related contaminants.

Sherrill, T.W.

1982-01-01

163

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

PubMed

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

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

2014-08-01

164

Microbial Contamination Detection in Water Resources: Interest of Current Optical Methods, Trends and Needs in the Context of Climate Change  

PubMed Central

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

Jung, Aude-Valerie; Le Cann, Pierre; Roig, Benoit; Thomas, Olivier; Baures, Estelle; Thomas, Marie-Florence

2014-01-01

165

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...

166

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

PubMed

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

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

2014-04-01

167

Assessment of microbial methane oxidation above a petroleum-contaminated aquifer using a combination of in situ techniques  

Microsoft Academic Search

Emissions of the greenhouse gas CH4, which is often produced in contaminated aquifers, are reduced or eliminated by microbial CH4 oxidation in the overlying vadose zone. The aim of this field study was to estimate kinetic parameters and isotope fractionation factors for CH4 oxidation in situ in the vadose zone above a methanogenic aquifer in Studen, Switzerland, and to characterize

Karina Urmann; Martin H. Schroth; Matthias Noll; Graciela Gonzalez-Gil; Josef Zeyer

2008-01-01

168

INSTRUCTIONAL DESIGN AND ASSESSMENT Parenterals Laboratory Course to Reduce Microbial Contamination Rates in Media Fill Tests Performed by Pharmacy Students  

Microsoft Academic Search

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 5 84) participated in this study. The aseptic technique procedures

Christine M. Isanhart; Kenneth L. McCall; Diane Kretschmer; Barbie A. Grimes

169

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

170

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

SciTech Connect

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.

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

171

Aquatic-surface microlayer contamination in Chesapeake Bay. Final report  

Microsoft Academic Search

The boundary between the atmosphere and the aquatic environment is an important biological habitat and a collection point for pollutants. The eggs and larvae of many fish and shellfish species float on, or come in contact with, the water surface throughout their early development. The aquatic-surface microlayer serves as a concentration point for metal and organic contaminants that have low

J. T. Hardy; B. A. Crecelius; L. D. Antrim; S. L. Kiesser; V. L. Broadhurst

1987-01-01

172

Proximal and point detection of contaminated surfaces using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We are actively investigating the use of Raman spectroscopy for proximal standoff detection of chemicals and explosive materials on surfaces. These studies include Raman Chemical Imaging of contaminated fingerprints for forensic attribution and the assessments of commercial handheld or portable Raman instruments operating with near-infrared (IR) as well as ultraviolet (UV) laser excitation specifically developed for on-the-move reconnaissance of chemical contamination. As part of these efforts, we have measured the Raman cross sections of chemical agents, toxic industrial chemicals, and explosives from the UV to NIR. We have also measured and modeled the effect interrogation angle has on the Raman return from droplets on man-made surfaces. Realistic droplet distributions have been modeled and tested against variations in surface scan patterns and laser spot size for determining the optimum scan characteristics for detection of relevant surface contamination.

Guicheteau, Jason A.; Christesen, Steven D.; Tripathi, Ashish; Emmons, Erik D.; Wilcox, Phillip G.; Emge, Darren K.; Pardoe, Ian J.; Fountain, Augustus W., III

2011-11-01

173

Aquatic-surface microlayer contamination in Chesapeake Bay. Final report  

SciTech Connect

The boundary between the atmosphere and the aquatic environment is an important biological habitat and a collection point for pollutants. The eggs and larvae of many fish and shellfish species float on, or come in contact with, the water surface throughout their early development. The aquatic-surface microlayer serves as a concentration point for metal and organic contaminants that have low water solubility or are associated with floatable particles. Coal-fired power plants may release organic and metal contaminants into the environment that subsequently concentrate on the water surface. The objectives of this study were to (1) determine the present degree of aquatic surface microlayer pollution at selected sites in Chesapeake Bay, and (2) provide a preliminary evaluation of sources (including power plants) contributing to any observed contamination.

Hardy, J.T.; Crecelius, B.A.; Antrim, L.D.; Kiesser, S.L.; Broadhurst, V.L.

1987-08-01

174

Microbial Communities in Contaminated Sediments, Associated with Bioremediation of Uranium to Submicromolar Levels?  

PubMed Central

Microbial enumeration, 16S rRNA gene clone libraries, and chemical analysis were used to evaluate the in situ biological reduction and immobilization of uranium(VI) in a long-term experiment (more than 2 years) conducted at a highly uranium-contaminated site (up to 60 mg/liter and 800 mg/kg solids) of the U.S. Department of Energy in Oak Ridge, TN. Bioreduction was achieved by conditioning groundwater above ground and then stimulating growth of denitrifying, Fe(III)-reducing, and sulfate-reducing bacteria in situ through weekly injection of ethanol into the subsurface. After nearly 2 years of intermittent injection of ethanol, aqueous U levels fell below the U.S. Environmental Protection Agency maximum contaminant level for drinking water and groundwater (<30 ?g/liter or 0.126 ?M). Sediment microbial communities from the treatment zone were compared with those from a control well without biostimulation. Most-probable-number estimations indicated that microorganisms implicated in bioremediation accumulated in the sediments of the treatment zone but were either absent or in very low numbers in an untreated control area. Organisms belonging to genera known to include U(VI) reducers were detected, including Desulfovibrio, Geobacter, Anaeromyxobacter, Desulfosporosinus, and Acidovorax spp. The predominant sulfate-reducing bacterial species were Desulfovibrio spp., while the iron reducers were represented by Ferribacterium spp. and Geothrix spp. Diversity-based clustering revealed differences between treated and untreated zones and also within samples of the treated area. Spatial differences in community structure within the treatment zone were likely related to the hydraulic pathway and to electron donor metabolism during biostimulation. PMID:18456853

Cardenas, Erick; Wu, Wei-Min; Leigh, Mary Beth; Carley, Jack; Carroll, Sue; Gentry, Terry; Luo, Jian; Watson, David; Gu, Baohua; Ginder-Vogel, Matthew; Kitanidis, Peter K.; Jardine, Philip M.; Zhou, Jizhong; Criddle, Craig S.; Marsh, Terence L.; Tiedje, James M.

2008-01-01

175

Microbial communities in contaminated sediments, associated with bioremediation of uranium to submicromolar levels  

SciTech Connect

Microbial enumeration, 16S rRNA gene clone libraries, and chemical analysis were used to evaluate the in situ biological reduction and immobilization of uranium(VI) in a long-term experiment (more than 2 years) conducted at a highly uranium-contaminated site (up to 60 mg/liter and 800 mg/kg solids) of the U.S. Department of Energy in Oak Ridge, TN. Bioreduction was achieved by conditioning groundwater above ground and then stimulating growth of denitrifying, Fe(III)-reducing, and sulfate-reducing bacteria in situ through weekly injection of ethanol into the subsurface. After nearly 2 years of intermittent injection of ethanol, aqueous U levels fell below the U.S. Environmental Protection Agency maximum contaminant level for drinking water and groundwater (<30 {micro}g/liter or 0.126 {micro}M). Sediment microbial communities from the treatment zone were compared with those from a control well without biostimulation. Most-probable-number estimations indicated that microorganisms implicated in bioremediation accumulated in the sediments of the treatment zone but were either absent or in very low numbers in an untreated control area. Organisms belonging to genera known to include U(VI) reducers were detected, including Desulfovibrio, Geobacter, Anaeromyxobacter, Desulfosporosinus, and Acidovorax spp. The predominant sulfate-reducing bacterial species were Desulfovibrio spp., while the iron reducers were represented by Ferribacterium spp. and Geothrix spp. Diversity-based clustering revealed differences between treated and untreated zones and also within samples of the treated area. Spatial differences in community structure within the treatment zone were likely related to the hydraulic pathway and to electron donor metabolism during biostimulation.

Cardenas, Erick [Michigan State University, East Lansing; Wu, Weimin [Stanford University; Leigh, Mary Beth [Michigan State University, East Lansing; Carley, Jack M [ORNL; Carroll, Sue L [ORNL; Gentry, Terry [Texas A& M University; Luo, Jian [Georgia Institute of Technology; Watson, David B [ORNL; Gu, Baohua [ORNL; Ginder-Vogel, Matthew A. [Stanford University; Kitanidis, Peter K. [Stanford University; Jardine, Philip M [ORNL; Zhou, Jizhong [University of Oklahoma, Norman; Criddle, Craig [Stanford University; Marsh, Terence [Michigan State University, East Lansing; Tiedje, James M. [Michigan State University, East Lansing

2008-03-01

176

Cross: Contaminant Removal Off Optical Surfaces In Space  

NASA Astrophysics Data System (ADS)

We are studying various approaches to cleaning contaminants off of optical surfaces at cryogenic temperatures. The techniques we are reviewing must be relatively efficient, portable, and not degrade the optical quality of the surface being cleaned, i.e., they must remove only the surface contamination layer, and leave the substrate untouched. Various techniques that we have considered include removal by electromagnetic waves by discharge-produced species, and by electron or ion bombardment. We have considered electromagnetic waves, generated by devices such as lasers or heat lamps, spanning a wavelength range from microwaves to soft X-rays. Proper wavelength selection offers great opportunities for efficient removal of selected contaminants. Discharge-produced species include such things as electronically excited metastables, slow ions, atoms, and free radicals. Although production efficiencies for energetic species in discharges are not high, some species contain sufficient energy to remove many contaminant molecules in one metastable-surface collision. In addition, the technique is surface specific, and should not lead to significant heating or damage of the substrate. Electron and ion bombardment techniques are widely used in a number of surface-cleaning applications. Great care, however, must be exercised in using these techniques to avoid damaging the optical quality of the surface We will present a review of the various techniques giving the strengths, weaknesses, and efficiencies of each. In addition, we have begun some experiments using selected techniques to test their efficacy. The experiment involves cleaning a thin layer of ice off a mirror surface main-tained at liquid nitrogen temperature in a vacuum chamber. An off-axis scattering technique is used to determine the degree of contamination of the surface, and, after the cleaning procedure, how well the surface quality has been restored.

Piper, Lawrence G.; Spencer, Mark N.; Woodward, Anne M.; Green, B. David

1987-01-01

177

Effects of the contamination environment on surfaces and materials  

NASA Technical Reports Server (NTRS)

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.

Maag, Carl R.

1989-01-01

178

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

PubMed Central

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

2014-01-01

179

Microbial ecological response of the intestinal flora of Peromyscus maniculatus and P. leucopus to heavy metal contamination.  

PubMed

Heavy metal contamination negatively affects natural systems including plants, birds, fish and bacteria by reducing biodiversity at contaminated sites. At the Tri-State Mining District, efforts have been made to remediate sites to mitigate the detrimental effects that contamination has caused on human health. While the remediation effort has returned the site to within federal safety standards, it is unclear if this effort is sufficient to restore floral and faunal communities. Intrinsic to ecosystem and organism health is the biodiversity and composition of microbial communities. We have taken advantage of recent advances in sequencing technology and surveyed the bacterial community of remediated and reference soils as well as the intestinal microbial community of two ubiquitous rodent species to provide insight on the impacts of residual heavy metal contamination on the ecosystem. Rodents found on the remediated site had reduced body mass, smaller body size and lower body fat than animals on reference sites. Using bar-coded, massively parallel sequencing, we found that bacterial communities in both the soil and Peromyscus spp. gastrointestinal tracts had no difference in diversity between reference and remediated sites but assemblages differed in response to contamination. These results suggest that niche voids left by microbial taxa that were unable to deal with the remnant levels of heavy metals on remediated sites were replaced by taxa that could persist in this environment. Whether this replacement provided similar ecosystem services as ancestral bacterial communities is unknown. PMID:20331771

Coolon, Joseph D; Jones, Kenneth L; Narayanan, Sanjeev; Wisely, Samantha M

2010-03-01

180

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

SciTech Connect

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.

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

1994-12-31

181

Evaluation of microbial contamination of tomatoes and peppers at retail markets in Monterrey, Mexico.  

PubMed

The source of a large outbreak of foodborne disease related to Salmonella-contaminated jalapeño peppers has been traced to Nuevo Leon, Mexico. The objective of this work was to evaluate the microbiological quality of tomatoes and jalapeño peppers from markets and supermarkets from the metropolitan area of Monterrey, Nuevo León, Mexico. One hundred sixty samples (40 bola tomatoes, 40 saladette [Roma] tomatoes, 40 serrano peppers, and 40 jalapeño peppers) were purchased. Stems from peppers were removed and analyzed separately. Samples were analyzed for indicator organisms and Salmonella, following the Mexican Official Methods. The results showed that the presence of indicator organisms varied among samples and origins, and levels were relatively high in peppers (average 4.4 to 4.7 log CFU/g for total mesophilic, 3.25 to 3.73 log CFU/g for total coliforms, and 1.69 log CFU/g for fecal coliforms). Saladette tomatoes and serrano peppers showed the greatest microorganism levels (?1 log CFU/g higher) in comparison with the other varieties. Pepper stems typically had indicator microbial levels ?1 to 2 log CFU/g higher than levels in smooth flesh. Only one tomato and one jalapeño sample were positive for Salmonella. However, in the case of the pepper, the contamination was found in the stem. Although the microbiological quality of tomatoes and peppers sampled was similar to that found in markets from developed countries, the presence of pathogens causes a risk of infection for consumers. PMID:23905810

Cárdenas, Carmen; Molina, Karina; Heredia, Norma; García, Santos

2013-08-01

182

Clayey materials in river basin enhancing microbial contamination of river water  

NASA Astrophysics Data System (ADS)

Mineral constituents of clay materials may promote interaction, adsorption and attachment of microorganisms, often resulting in biofilms' formation. In this study investigation is made to determine how littoral clayey materials on the shores of a river promote accumulation of bacteria and increase contamination of river water. Clayey samples were collected at various points along the shore of a river around Mondeor in Johannesburg and the mineralogical composition was determined using XRD and XRF. Microorganisms in clay-biofilm and river water were identified by DNA sequencing and plate count. Results showed that total coliforms, Escherichia coli, Pseudomonas sp. and presumptive indigenous microorganisms attached to littoral clayey materials containing the mineral muscovite (characterising argillaceous soils). Bacteria number on clayey materials was significantly higher than on overlying water especially before rainy season. However a decrease of the number of bacteria in clayey materials concurrent with an increase in the number of suspended bacteria after rain events, was the result of the action of high and fast flows in the basin, eroding the biofilms. Attachment of microorganisms in clayey material as observed in this study could be ascribed to the glue-like aspect of soil (due to muscovite) that facilitates adhesion. It therefore demonstrates the potential of clayey materials to encourage biofilm formation and enhance microbial contamination of river water as shown here.

Fosso-Kankeu, E.; Mulaba-Bafubiandi, A. F.; Barnard, T. G.

183

Microbial contamination of dental unit waterlines in dental practices in Hesse, Germany: A cross-sectional study  

PubMed Central

The quality of water from dental units is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from the dental unit. This study analyzed the microbial quality of water obtained for periodical monitoring from 56 dental units in different dental practices in Hesse. Contamination by Legionella spp., Pseudomonas aeruginosa, and increased total colony counts were detected in 27.8%, 3.5%, and 17% of samples. Legionella pneumophila serogroup 1 accounted for 28% of Legionella isolates. The Legionella concentration was >100 cfu/100 ml in 84% of contaminated samples. Samples collected from an instrument channel were more frequently contaminated by Legionella than those from cup filler (41.7% vs. 18.6%, p = 0.02). After release of these results, decontamination measures were performed in units that had revealed unsatisfactory results. The outcome of the intervention was followed-up by microbiological analysis. At follow-up, 65.2% and 72.7% of waterlines that had previously been contaminated by Legionella or had shown increased total colony counts were free of contamination. Our results show a high rate of contamination of water from dental units in dental practices in Hesse. They highlight the risk of exposure for patients and personnel and the need for effective strategies to reduce microbial contamination. PMID:24265918

Hack, Alfons

2013-01-01

184

Microbial contamination of dental unit waterlines in dental practices in Hesse, Germany: A cross-sectional study.  

PubMed

The quality of water from dental units is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from the dental unit. This study analyzed the microbial quality of water obtained for periodical monitoring from 56 dental units in different dental practices in Hesse. Contamination by Legionella spp., Pseudomonas aeruginosa, and increased total colony counts were detected in 27.8%, 3.5%, and 17% of samples. Legionella pneumophila serogroup 1 accounted for 28% of Legionella isolates. The Legionella concentration was >100 cfu/100 ml in 84% of contaminated samples. Samples collected from an instrument channel were more frequently contaminated by Legionella than those from cup filler (41.7% vs. 18.6%, p = 0.02). After release of these results, decontamination measures were performed in units that had revealed unsatisfactory results. The outcome of the intervention was followed-up by microbiological analysis. At follow-up, 65.2% and 72.7% of waterlines that had previously been contaminated by Legionella or had shown increased total colony counts were free of contamination. Our results show a high rate of contamination of water from dental units in dental practices in Hesse. They highlight the risk of exposure for patients and personnel and the need for effective strategies to reduce microbial contamination. PMID:24265918

Arvand, Mardjan; Hack, Alfons

2013-03-01

185

Using a portable mass spectrometer to measure surface contamination  

SciTech Connect

One of the major sources of hazardous waste and VOC air emissions throughout manufacturing industry is parts and equipment cleaning operations. Modification of the cleaning process to use non-hazardous cleaning agents may be the best way to these sources, but some operations still require the use of hazardous solvents. Monitoring the contamination levels during cleaning operations can provide useful feedback for reducing waste generation and air emissions due to over- or under-cleaning. Near real-time evaluation of cleaning operations can help reduce pollution in a wide variety of industries, including aerospace, electronics, and metal finishing industries. The authors have developed a mass spectrometry based analyzer that has similar or better sensitivity than ellipsometry or FTIR and is more tolerant of surface conditions and composition. In addition, the instrument is relatively portable and can be used to help identify unknown surface contamination. This method uses vacuum and thermal desorption to remove volatile and semi-volatile contaminants from the surface. A quadrupole mass spectrometer is used to identify and measure the contamination. A bench-scale model of this {open_quotes}contamination analysis unit{close_quotes} employs a residual gas analyzer (RGA) mated to a small, internally heated inlet that samples a surface.

Gregg, H.; Meltzer, M.; Lindsey, J.; Edberg, H. [Lawrence Livermore National Lab., CA (United States)

1995-12-31

186

Antineoplastic drugs contamination of workplace surfaces in two Portuguese hospitals.  

PubMed

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

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

2014-11-01

187

Trophic interactions induce spatial self-organization of microbial consortia on rough surfaces.  

PubMed

The spatial context of microbial interactions common in natural systems is largely absent in traditional pure culture-based microbiology. The understanding of how interdependent microbial communities assemble and coexist in limited spatial domains remains sketchy. A mechanistic model of cell-level interactions among multispecies microbial populations grown on hydrated rough surfaces facilitated systematic evaluation of how trophic dependencies shape spatial self-organization of microbial consortia in complex diffusion fields. The emerging patterns were persistent irrespective of initial conditions and resilient to spatial and temporal perturbations. Surprisingly, the hydration conditions conducive for self-assembly are extremely narrow and last only while microbial cells remain motile within thin aqueous films. The resulting self-organized microbial consortia patterns could represent optimal ecological templates for the architecture that underlie sessile microbial colonies on natural surfaces. Understanding microbial spatial self-organization offers new insights into mechanisms that sustain small-scale soil microbial diversity; and may guide the engineering of functional artificial microbial consortia. PMID:25343307

Wang, Gang; Or, Dani

2014-01-01

188

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

PubMed

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

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

2013-01-01

189

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

PubMed Central

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

Salvador, Angelo C.; Baptista, Ines; Barros, Antonio S.; Gomes, Newton C. M.; Cunha, Angela; Almeida, Adelaide; Rocha, Silvia M.

2013-01-01

190

Microbial Surfaces and their Effects on Carbonate Mineralization  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

191

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

PubMed Central

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

Luksamijarulkul, Pipat; Aiempradit, Natkitta; Vatanasomboon, Pisit

2014-01-01

192

Screening Surface Contamination with BetaCage  

SciTech Connect

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.

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

193

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

Microsoft Academic Search

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 different RTE products are needed to ensure RTE food safety. The objectives of this study were

Shiowshuh Sheen; Cheng-An Hwang

2010-01-01

194

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

SciTech Connect

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.

C.J. Miller; T.S. Yoder

2010-06-01

195

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

NASA Astrophysics Data System (ADS)

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.

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

2009-05-01

196

Dimensionless parameters to summarize the influence of microbial growth and inhibition on the bioremediation of groundwater contaminants.  

PubMed

Monod expressions are preferred over zero- and first-order decay expressions in modeling contaminants biotransformation in groundwater because they better represent complex conditions. However, the wide-range of values reported for Monod parameters suggests each case-study is unique. Such uniqueness restricts the usefulness of modeling, complicates an interpretation of natural attenuation and limits the utility of a bioattenuation assessment to a small number of similar cases. In this paper, four Monod-based dimensionless parameters are developed that summarize the effects of microbial growth and inhibition on groundwater contaminants. The four parameters represent the normalized effective microbial growth rate (?), the normalized critical contaminant/substrate concentration (S*), the critical contaminant/substrate inhibition factor (N), and the bioremediation efficacy (?*). These parameters enable contaminated site managers to assess natural attenuation or augmented bioremediation at multiple sites and then draw comparisons between disparate remediation activities, sites and target contaminants. Simulations results are presented that reveal the sensitivity of these dimensionless parameters to Monod parameters and varying electron donor/acceptor loads. These simulations also show the efficacy of attenuation (?*) varying over space and time. Results suggest electron donor/acceptor amendments maintained at relative concentrations S* between 0.5 and 1.5 produce the highest remediation efficiencies. Implementation of the developed parameters in a case study proves their usefulness. PMID:21181489

Mohamed, M; Hatfield, K

2011-09-01

197

Influence of recovery method and microbial contamination on the response to freezing-thawing in ibex (Capra pyrenaica) epididymal spermatozoa.  

PubMed

The method of sperm recovery may influence the initial quality of sperm samples and their response to freezing-thawing. The aim of the present work was to compare two methods for collecting epididymal spermatozoa in order to improve the quality of recovered sperm and reduce possible contamination. Testes were obtained from 23 legally hunted, adult ibex males. The sperm mass of the right epididymis was collected by small longitudinal and transverse cuts made in the cauda epididymidis. The sperm mass of the left epididymis was collected by retrograde flushing from the vas deferens to the cauda epididymidis (using a cannula), employing a Tris, citric acid, glucose, egg yolk-based medium. The flushing method recovered more spermatozoa (P<0.001) than the cutting method. After freezing-thawing, greater acrosomes damage (P<0.001) and more morphological abnormalities (P<0.05) were seen among the sperm cells recovered by the cutting method than among those obtained by retrograde flushing. The method of sperm recovery did not, however, influence the microbial contamination rate. In frozen-thawed samples that were microbially contaminated, motility was significantly reduced (P<0.05) and membrane integrity tended to be poorer (P=0.06). In conclusion, retrograde flushing is recommended for ibex sperm collection since it would appear that microbial contamination is no more of a problem than that encountered with the cutting method, while a larger number of sperm cells more resistant to freezing-thawing can be obtained. PMID:19786008

Santiago-Moreno, Julian; Astorga, Rafael J; Luque, Inmaculada; Coloma, Miguel A; Toledano-Díaz, Adolfo; Pulido-Pastor, Antonio; Gómez-Guillamon, Felix; Salas-Vega, Ricardo; López-Sebastián, Antonio

2009-12-01

198

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

PubMed Central

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

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

199

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

PubMed Central

Microbial community composition associated with benzene oxidation under in situ Fe(III)-reducing conditions 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 uncontaminated zones. Denaturing gradient gel electrophoresis of 16S rDNA sequences amplified with bacterial or Geobacteraceae-specific primers indicated significant differences in the composition of the microbial communities at the different sites. Most notable was a selective enrichment of microorganisms in the Geobacter cluster seen in the benzene-degrading sediments. This finding was in accordance with phospholipid fatty acid analysis and most-probable-number–PCR enumeration, which indicated that members of the family Geobacteraceae were more numerous in these sediments. A benzene-oxidizing Fe(III)-reducing enrichment culture was established from benzene-degrading sediments and contained an organism closely related to the uncultivated Geobacter spp. This genus contains the only known organisms that can oxidize aromatic compounds with the reduction of Fe(III). Sequences closely related to the Fe(III) reducer Geothrix fermentans and the aerobe Variovorax paradoxus were also amplified from the benzene-degrading enrichment and were present in the benzene-degrading sediments. However, neither G. fermentans nor V. paradoxus is known to oxidize aromatic compounds with the reduction of Fe(III), and there was no apparent enrichment of these organisms in the benzene-degrading sediments. These results suggest that Geobacter spp. play an important role in the anaerobic oxidation of benzene in the Bemidji aquifer and that molecular community analysis may be a powerful tool for predicting a site’s capacity for anaerobic benzene degradation. PMID:10388703

Rooney-Varga, Juliette N.; Anderson, Robert T.; Fraga, Jocelyn L.; Ringelberg, David; Lovley, Derek R.

1999-01-01

200

Characterization of Archaeal Community in Contaminated and Uncontaminated Surface Stream Sediments  

SciTech Connect

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.

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

201

Characterization of archaeal community in contaminated and uncontaminated surface stream sediments.  

PubMed

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. PMID:20725722

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; Palumbo, Anthony V

2010-11-01

202

Waveform tomography at a groundwater contamination site: Surface reflection data  

E-print Network

Superfund sites where there are various con- taminants at the earth's surface or in the shallow subsurface of Superfund sites awaiting remedia- tion. The groundwater-contamination site at Hill Air Force Base HAFB in Utah was included in the Superfund list in September 1983. In planning remediation, it is important

Pratt, R. Gerhard

203

An Exercise in Evaluating the Contamination Potential of Surface Impoundments.  

ERIC Educational Resources Information Center

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)

Tinker, John R., Jr.

1982-01-01

204

Electrical conductivity and emerging contaminant as markers of surface freshwater contamination by wastewater.  

PubMed

The use of chemical markers of undoubted anthropogenic sources for surface freshwater contamination by wastewaters was evaluated employing correlations observed between measured physico-chemical parameters as the electrical conductivity and the concentration of different emerging organic compounds. During the period from April/2011 to April/2012 spatial-temporal variations and contamination patterns of two rivers (Piraí and Jundiaí rivers), São Paulo state, Brazil were evaluated. Seven physico-chemical parameters and concentrations of different classes of emerging contaminants were determined in samples collected in seven field campaigns. The high linear correlation coefficients obtained for the compounds diclofenac (r=0.9085), propanolol (r=0.8994), ibuprofen (r=0.8720) and atenolol (r=0.7811) with electrical conductivity, also corroborated by principal component analysis (PCA), point to the potential use of these compounds as markers of investigated surface water contamination by wastewaters. Due to specific inputs, these environmental markers showed very good effectiveness for the identification and differentiation of water body contamination by discharges of treated and untreated urban sewage. PMID:24686141

de Sousa, Diana Nara Ribeiro; Mozeto, Antonio Aparecido; Carneiro, Renato Lajarim; Fadini, Pedro Sergio

2014-06-15

205

Growth kinetics of some subsurface microbial strains using naphthalene as a probe contaminant  

Microsoft Academic Search

The focus of this study is the unravelling of the microbial dynamics of the biodegradation of naphthalene, a polycyclic aromatic hydrocarbon, in an aqueous–sediment matrix. The Pour plate procedure was adopted for the isolation of the microbial colonies, while the sub?culturing of the isolates was based on their cultural (biochemical) and morphological characteristics. Investigations showed that the microbial colonies consisted

C. N. Owabor; S. E. Ogbeide; A. A. Susu

2011-01-01

206

Spatial and temporal changes in microbial community structure associated with recharge-influenced chemical gradients in a contaminated aquifer  

USGS Publications Warehouse

In a contaminated water-table aquifer, we related microbial community structure on aquifer sediments to gradients in 24 geochemical and contaminant variables at five depths, under three recharge conditions. Community amplified ribsosomal DNA restriction analysis (ARDRA) using universal 16S rDNA primers and denaturing gradient gel electrophoresis (DGGE) using bacterial 16S rDNA primers indicated: (i) communities in the anoxic, contaminated central zone were similar regardless of recharge; (ii) after recharge, communities at greatest depth were similar to those in uncontaminated zones; and (iii) after extended lack of recharge, communities at upper and lower aquifer margins differed from communities at the same depths on other dates. General aquifer geochemistry was as important as contaminant or terminal electron accepting process (TEAP) chemistry in discriminant analysis of community groups. The Shannon index of diversity (H) and the evenness index (E), based on DGGE operational taxonomic units (OTUs), were statistically different across community groups and aquifer depths. Archaea or sulphate-reducing bacteria 16S rRNA abundance was not clearly correlated with TEAP chemistry indicative of methanogenesis or sulphate reduction. Eukarya rRNA abundance varied by depth and date from 0 to 13% of the microbial community. This contaminated aquifer is a dynamic ecosystem, with complex interactions between physical, chemical and biotic components, which should be considered in the interpretation of aquifer geochemistry and in the development of conceptual or predictive models for natural attenuation or remediation.

Haack, S. K.; Fogarty, L. R.; West, T. G.; Alm, E. W.; McGuire, J. T.; Long, D. T.; Hyndman, D. W.; Forney, L. J.

2004-01-01

207

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

SciTech Connect

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.

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

1987-12-01

208

Rumen effective degradability of amino acids from soybean meal corrected for microbial contamination.  

PubMed

Rumen degradation kinetics and effective degradability of individual amino acids, total analysed amino acids (TAA) and crude protein (CP) of soybean meal were measured on four rumen-cannulated wethers using the nylon bag technique. Microbial contamination of the incubated residues was corrected using a continuous 15N intraruminal infusion and isolated solid associated bacteria as a reference sample. TAA showed a lower soluble fraction (14.9 vs. 20.8%; P < 0.01), a similar insoluble-degradable fraction (79.0 vs. 79.2%) and a higher degradation rate (11.5 vs. 8.4% x h(-1); P < 0.05) than CP. As a consequence, effective degradability was similar for TAA and CP (74.7 vs. 75.7%). Degradability values of individual amino acids varied moderately (range: +/-6% of TAA degradability). Valine, isoleucine, leucine, alanine, aspartic acid and tyrosine showed significantly lower degradability than TAA, while the opposite effect was observed for histidine, threonine and glutamic acid. Degradability of individual amino acids was related to their soluble fraction (r = 0.877; P<0.001). PMID:11286287

González, J; Rodríguez, C A; Centeno, C; Lamnari, F

2000-01-01

209

Chemical and microbial community analysis during aerobic biostimulation assays of non-sulfonated alkyl-benzene-contaminated groundwater  

Microsoft Academic Search

A chemical and microbial characterization of lab-scale biostimulation assays with groundwater samples taken from an industrial\\u000a site in which the aquifer had been contaminated by linear non-sulfonate alkyl benzenes (LABs) was carried out for further\\u000a field-scale bioremediation purposes. Two lab-scale biodegradability assays were performed, one with a previously obtained\\u000a gas-oil-degrading consortium and another with the native groundwater flora. Results for

Eulàlia Martínez-Pascual; Nuria Jiménez; Georgina Vidal-Gavilan; Marc Viñas; A. M. Solanas

2010-01-01

210

Impacts of heavy metal contamination and phytoremediation on a microbial community during a twelve-month microcosm experiment  

Microsoft Academic Search

The effects of heavy metals and phytoextraction practices on a soil microbial community were studied during 12 months using a hyperaccumulating plant (Thlaspi caerulescens) grown in an artificially contaminated soil. The 16S ribosomal RNA genes of the Bacteria and the ?-Proteobacteria and the amoA gene (encoding the ?-subunit of ammonia monooxygenase) were PCR-amplified and analysed by denaturing gradient gel electrophoresis

Fabienne Gremion; Antonis Chatzinotas; Karin Kaufmann; William Von Sigler; Hauke Harms

2004-01-01

211

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...

212

Surface contamination of cyclophosphamide packaging and surface contamination with antineoplastic drugs in a hospital pharmacy in Sweden.  

PubMed

Workplaces, e.g. hospital pharmacies and hospital departments, where antineoplastic drugs are handled might be contaminated with these drugs, and pharmacy personnel and health care workers may be exposed. In this study potential sources for exposure of antineoplastic drugs were investigated. Unbroken drug vials and tablet blister packages, both containing cyclophosphamide (CP) and their outer packaging were wipe sampled. Analysis was performed by liquid chromatography combined with tandem mass spectrometry (LC-MS/MS). The result showed that almost every part of the primary packaging was contaminated with CP and ifosfamide (IF). However, the amounts of CP and IF were low, and most likely not harmful for the personnel handling these packaging in association with drug preparation. The contamination must originate from the pharmaceutical manufacturer. Different surfaces in the preparation unit of a Swedish hospital pharmacy were also investigated at two different occasions by wipe sampling. In the preparation unit CP and IF were found as contaminants on the majority of the investigated surfaces. After the first measurement the hospital pharmacy improved its routines. Lower amounts of CP and IF were detected at the second measurement. A low degree of contamination with CP and IF was also detected on the floor outside the preparation unit and this indicated a small distribution of antineoplastic drugs to the surroundings. PMID:16126760

Hedmer, M; Georgiadi, A; Bremberg, E Rämme; Jönsson, B A G; Eksborg, S

2005-10-01

213

Sustained Reduction of Microbial Burden on Common Hospital Surfaces through Introduction of Copper  

PubMed Central

The contribution of environmental surface contamination with pathogenic organisms to the development of health care-associated infections (HAI) has not been well defined. The microbial burden (MB) associated with commonly touched surfaces in intensive care units (ICUs) was determined by sampling six objects in 16 rooms in ICUs in three hospitals over 43 months. At month 23, copper-alloy surfaces, with inherent antimicrobial properties, were installed onto six monitored objects in 8 of 16 rooms, and the effect that this application had on the intrinsic MB present on the six objects was assessed. Census continued in rooms with and without copper for an additional 21 months. In concert with routine infection control practices, the average MB found for the six objects assessed in the clinical environment during the preintervention phase was 28 times higher (6,985 CFU/100 cm2; n = 3,977 objects sampled) than levels proposed as benign immediately after terminal cleaning (<250 CFU/100 cm2). During the intervention phase, the MB was found to be significantly lower for both the control and copper-surfaced objects. Copper was found to cause a significant (83%) reduction in the average MB found on the objects (465 CFU/100 cm2; n = 2714 objects) compared to the controls (2,674 CFU/100 cm2; n = 2,831 objects [P < 0.0001]). The introduction of copper surfaces to objects formerly covered with plastic, wood, stainless steel, and other materials found in the patient care environment significantly reduced the overall MB on a continuous basis, thereby providing a potentially safer environment for hospital patients, health care workers (HCWs), and visitors. PMID:22553242

Attaway, Hubert H.; Sharpe, Peter A.; John, Joseph; Sepkowitz, Kent A.; Morgan, Andrew; Fairey, Sarah E.; Singh, Susan; Steed, Lisa L.; Cantey, J. Robert; Freeman, Katherine D.; Michels, Harold T.; Salgado, Cassandra D.

2012-01-01

214

Reactor surface contamination stabilization. Innovative technology summary report  

SciTech Connect

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.

NONE

1998-11-01

215

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

NASA Astrophysics Data System (ADS)

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.

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

2004-12-01

216

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

PubMed Central

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

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

2013-01-01

217

Contamination of aluminum and painted surfaces exposed to tritium  

SciTech Connect

There are a number of facilities in the world that handle large quantities of tritium. Many more are envisioned as deuterium-tritium-burning fusion test and power reactors come on line. To cope with increasing environmental concerns, many of the designs of such facilities will probably incorporate some type of emergency air detritiation system. To better design the ventilation and detritiation systems for such facilities, more data are needed regarding the conversion of HT to HTO under realistic release conditions and the uptake and subsequent release (outgassing) of surfaces contaminated by airborne tritium. Surface contamination studies begun several years ago at the Los Alamos National Lab. using small, painted samples were recently expanded using a large exposure chamber. This paper summarizes the results of the earlier unpublished work and compares the newest data with recently reported results and their implication for tritium facilities.

Jalbert, R.A.; Brereton, S.J.; Holland, D.F.

1986-01-01

218

MEETING REPORT: SRP Meeting: Surface and Airborne Contamination  

Microsoft Academic Search

AWE Aldermaston, 26-27 June 2000 AWE Aldermaston recently opened its doors to both United Kingdom and international delegates for a two-day scientific meeting and tour on the subject of 'Surface and Airborne Contamination'. The meeting was held on the 26-27 June 2000 and involved nearly 200 delegates and 8 speakers from the defence, nuclear industries, health sector and begulatory bodies.

Steven Chandler

2000-01-01

219

Proximal and point detection of contaminated surfaces using Raman spectroscopy  

Microsoft Academic Search

We are actively investigating the use of Raman spectroscopy for proximal standoff detection of chemicals and explosive materials on surfaces. These studies include Raman Chemical Imaging of contaminated fingerprints for forensic attribution and the assessments of commercial handheld or portable Raman instruments operating with near-infrared (IR) as well as ultraviolet (UV) laser excitation specifically developed for on-the-move reconnaissance of chemical

Jason A. Guicheteau; Steven D. Christesen; Ashish Tripathi; Erik D. Emmons; Phillip G. Wilcox; Darren K. Emge; Ian J. Pardoe; Augustus W. Fountain III

2011-01-01

220

Use of Microarray-based Genomic Technologies for Assessing Microbial Community Composition and Dynamics in Contaminated Groundwater  

NASA Astrophysics Data System (ADS)

To effectively monitor microbial populations involved in various important processes, a 50-mer-based oligonucleotide microarray was developed based on known genes and pathways involved in: biodegradation, metal resistance and reduction, denitrification, nitrification, nitrogen fixation, methane oxidation, methanogenesis, carbon polymer decomposition, and sulfate reduction. This array contains approx 2000 unique and group-specific probes with <85% similarity to their non-target sequences. Based on artificial probes, our results showed that at hybridization conditions of 50oC and 50% formamide, the 50-mer microarray hybridization can differentiate sequences having <88% similarity. Specificity tests with representative pure cultures indicated that the designed probes on the arrays appeared to be specific to their corresponding target genes. Detection limits were about 5-10ng genomic DNA in the absence of background DNA, and 50-100ng ( ˜1.3 ¡A107 cells) in the presence background DNA. Strong linear relationships between signal intensity and target DNA and RNA concentration were observed (r2 = 0.95-0.99). Real-time PCR analysis of 12 representative genes was consistent with microarray-based quantification (r2 = 0.95). Also novel approaches were developed and used to increase microarray detection sensitivity of both DNA and mRNA. Application of these array-based technologies to analyze microbial communities in contaminated groundwaters from the US Department of Energy¡_s Natural and Accelerated Bioremediation Research Program (NABIR) Field Research Center at Oak Ridge, TN, demonstrated that it is feasible to biostimulate the indigenous microbial populations for contaminant remediation but the process could be very complicated due to highly spatial heterogeneous microbial distributions. Based on these results, more comprehensive functional gene arrays containing ˜27,000 probes from the genes important for biogeochemical cycling of C, N, S, P, metal resistance and contaminant degradation have been designed and constructed. This is the most comprehensive array available so far for environmental studies and will also be useful for biogeochemistry studies in general.

Zhou, J.; Schadt, C.; Gentry, T.; He, Z.; Wu, L.; Rhee, S.; Liu, X.; Liebich, J.; Chong, S.; Yang, Z.; Gao, H.

2004-12-01

221

Impact of substratum surface on microbial community structure and treatment performance in biological aerated filters.  

PubMed

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

Kim, Lavane; Pagaling, Eulyn; Zuo, Yi Y; Yan, Tao

2014-01-01

222

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

PubMed Central

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

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

2014-01-01

223

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

SciTech Connect

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.

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

224

Combining hierarchical surface roughness with fluorinated surface chemistry to preserve superhydrophobicity after organic contamination  

NASA Astrophysics Data System (ADS)

Surfaces exhibiting superhydrophobicity are attracting commercial and academic attention because of their potential applications in, for example, self-cleaning utensils, microfluidic systems, and microelectronic devices. In this study, we prepared a fluorinated superhydrophobic surface displaying nanoscale roughness, a superhydrophobic surface possessing a micro- and nanoscale binary structure, and a fluorinated superhydrophobic surface possessing such a binary structure. We investigated the effects of the (i) hierarchy of the surface topography and (ii) the surface chemical composition of the superhydrophobic carbon nanotube/polybenzoxazine coatings on their ability to retain superhydrophobicity upon contamination with particles and organic matter, an important characteristic for maintaining non-wetting properties under outdoor conditions. We have found that the topographical microstructure and the surface chemical composition are both important factors for preservation of the non-wetting properties of such superhydrophobic surfaces upon contamination with organic matter.

Wang, Chih-Feng; Hung, Shih-Wei; Kuo, Shiao-Wei; Chang, Chi-Jung

2014-11-01

225

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

USGS Publications Warehouse

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.

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

1997-01-01

226

A comparative review of optical surface contamination assessment techniques  

NASA Technical Reports Server (NTRS)

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.

Heaney, James B.

1987-01-01

227

Utility of Microbial Source-Tracking Markers for Assessing Fecal Contamination in the Portage River Watershed, Northwestern Ohio, 2008  

USGS Publications Warehouse

An influx of concentrated animal feeding operations in northwest Ohio has prompted local agencies to examine the effects of these industrial farms on water quality in the upper Portage River watershed. The utility of microbial source-tracking (MST) tools as a means of characterizing sources of fecal contamination in the watershed was evaluated. From 2007 to 2008, scientists with the U.S. Geological Survey, Bowling Green State University, and the Wood County Health Department collected and analyzed 17 environmental samples and 13 fecal source samples for Bacteroides-based host-associated DNA markers. At many of the environmental sites tested, MST marker results corroborated the presumptive fecal contamination sources. Results from this demonstration study support the utility of using MST with host-specific molecular markers to characterize the sources of fecal contamination in the Portage River watershed.

Kephart, Christopher M.; Bushon, Rebecca N.

2010-01-01

228

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

PubMed

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

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

2012-12-01

229

Microbial Contamination of Date Rutab Collected from the Markets of Al-Hofuf City in Saudi Arabia  

PubMed Central

The microbial contamination of 60 samples from six date cultivars in the rutab stage purchased from different retail outlets in AL-Hofuf City, Saudi Arabia was studied. All samples were found contaminated with aerobic mesophilic bacteria at loads in the order 102 to 105?cfu/cm2 with some significant differences among varieties that can be attributed to differences in the weather conditions during rutab season. Also all samples, except only one, were contaminated with molds and yeasts at loads in the order 102 to 103?cfu/cm2. Potentially pathogenic Staphylococcus aureus was detected in 57 samples and A. flavus/parasiticus in 13 samples, while coliforms were detected in 39 samples. PMID:22619578

Hamad, Siddig H.; Saleh, Farag A.; Al-Otaibi, Mutlag M.

2012-01-01

230

Diversity, Abundance, and Consistency of Microbial Oxygenase Expression and Biodegradation in a Shallow Contaminated Aquifer? †  

PubMed Central

The diversity of Rieske dioxygenase genes and short-term temporal variability in the abundance of two selected dioxygenase gene sequences were examined in a naphthalene-rich, coal tar waste-contaminated subsurface study site. Using a previously published PCR-based approach (S. M. Ní Chadhain, R. S. Norman, K. V. Pesce, J. J. Kukor, and G. J. Zylstra, Appl. Environ. Microbiol. 72:4078-4087, 2006) a broad suite of genes was detected, ranging from dioxygenase sequences associated with Rhodococcus and Sphingomonas to 32 previously uncharacterized Rieske gene sequence clone groups. The nag genes appeared frequently (20% of the total) in two groundwater monitoring wells characterized by low (?102 ppb; ?1 ?M) ambient concentrations of naphthalene. A quantitative competitive PCR assay was used to show that abundances of nag genes (and archetypal nah genes) fluctuated substantially over a 9-month period. To contrast short-term variation with long-term community stability, in situ community gene expression (dioxygenase mRNA) and biodegradation potential (community metabolism of naphthalene in microcosms) were compared to measurements from 6 years earlier. cDNA sequences amplified from total RNA extracts revealed that nah- and nag-type genes were expressed in situ, corresponding well with structural gene abundances. Despite evidence for short-term (9-month) shifts in dioxygenase gene copy number, agreement in field gene expression (dioxygenase mRNA) and biodegradation potential was observed in comparisons to equivalent assays performed 6 years earlier. Thus, stability in community biodegradation characteristics at the hemidecadal time frame has been documented for these subsurface microbial communities. PMID:19700556

Yagi, Jane M.; Madsen, Eugene L.

2009-01-01

231

Microbial Diversity in a Hydrocarbon- and Chlorinated-Solvent-Contaminated Aquifer Undergoing Intrinsic Bioremediation  

PubMed Central

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 (OP5, 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. PMID:9758812

Dojka, Michael A.; Hugenholtz, Philip; Haack, Sheridan K.; Pace, Norman R.

1998-01-01

232

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

USGS Publications Warehouse

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.

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

1998-01-01

233

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

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

234

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

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

235

Microbial carbon and nitrogen fixation on the surface of glaciers and ice sheets  

NASA Astrophysics Data System (ADS)

Studying the microbial sequestration of atmospheric carbon dioxide (via net autochthonous production) and nitrogen (via nitrogen fixation) into organic matter on the surface of glaciers and ice sheets is important for three main reasons. First, they can provide essential nutrients for supporting microbial ecosystems in these cold, typically nutrient-poor environments. Second, nutrients formed in the supraglacial environment may be important for sustaining hydrologically connected subglacial and downstream (e.g. fjords, near-shore marine) ecosystems. Third, organic matter produced or transformed by microbial activity can alter the albedo of ice, either directly by the production of dark pigments, or indirectly through the trapping and agglutination of dark mineral via the production of exopolysaccharides. Here, we present recent results of microbial carbon and nitrogen fixation in surface sediment (cryoconite) on Arctic and Antarctic glaciers and the Greenland Ice Sheet ablation zone. Results suggest that the fixation and recycling of autochthonous carbon in cryoconite on glaciers and ice sheets can support a significant fraction of the total microbial activity in the supraglacial environment during the ablation season. Nitrogen fixation can be important as a nitrogen source for microbial communities on both Arctic and Antarctic glaciers during the main ablation season. Nitrogen fixation could feasibly exceed precipitation as a source of nitrogen to microbial communities in debris rich zones on the margins of the Greenland Ice Sheet, aiding the colonization and subsequent 'greening' of subglacial and moraine derived debris.

Telling, J.; Anesio, A. M.; Stibal, M.; Hawkings, J.; Bellas, C. M.; Tranter, M.; Wadham, J. L.; Cook, J.; Hodson, A. J.; Yallop, M.; Barker, G.; Butler, C. E.; Fountain, A. G.; Nylen, T.; Irvine-Fynn, T. D.; Sole, A. J.; Nienow, P. W.

2012-12-01

236

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

PubMed

This study provided insight into the degree of microbial contamination in the processing chain of prepacked (bagged) lettuce in two Belgian fresh-cut produce processing companies. The pathogens Salmonella and Listeria monocytogenes were not detected. Total psychrotrophic aerobic bacterial counts (TPACs) in water samples, fresh produce, and environmental samples suggested that the TPAC is not a good indicator of overall quality and best manufacturing practices during production and processing. Because of the high TPACs in the harvested lettuce crops, the process water becomes quickly contaminated, and subsequent TPACs do not change much throughout the production process of a batch. The hygiene indicator Escherichia coli was used to assess the water management practices in these two companies in relation to food safety. Practices such as insufficient cleaning and disinfection of washing baths, irregular refilling of the produce wash baths with water of good microbial quality, and the use of high product/water ratios resulted in a rapid increase in E. coli in the processing water, with potential transfer to the end product (fresh-cut lettuce). The washing step in the production of fresh-cut lettuce was identified as a potential pathway for dispersion of microorganisms and introduction of E. coli to the end product via cross-contamination. An intervention step to reduce microbial contamination is needed, particularly when no sanitizers are used as is the case in some European Union countries. Thus, from a food safety point of view proper water management (and its validation) is a critical point in the fresh-cut produce processing industry. PMID:22488054

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

2012-04-01

237

Mobilization of heavy metals from contaminated calcareous soils by plant born, microbial and synthetic chelators and their uptake by wheat plants  

Microsoft Academic Search

Extractability of heavy metals (Zn, Ni, and Cd) from a contaminated soil by plant bom (phytosiderophores), microbial (desferal) and synthetic chelators (DTPA) has been studied. For this purpose a highly calcareous soil was contaminated by amendments of sewage sludge or a mixture of inorganic Zn, Ni and Cd salts at two different rates during a one month incubation period. After

Fikry Awad; Volker Römheld

2000-01-01

238

21 CFR 111.10 - What requirements apply for preventing microbial contamination from sick or infected personnel...  

...that may result in contamination any person who, by medical examination, the person's acknowledgement, or...contact surfaces are washed; (8) Not eating food, chewing gum, drinking beverages, or using tobacco products...

2014-04-01

239

21 CFR 111.10 - What requirements apply for preventing microbial contamination from sick or infected personnel...  

Code of Federal Regulations, 2012 CFR

...that may result in contamination any person who, by medical examination, the person's acknowledgement, or...contact surfaces are washed; (8) Not eating food, chewing gum, drinking beverages, or using tobacco products...

2012-04-01

240

21 CFR 111.10 - What requirements apply for preventing microbial contamination from sick or infected personnel...  

Code of Federal Regulations, 2013 CFR

...that may result in contamination any person who, by medical examination, the person's acknowledgement, or...contact surfaces are washed; (8) Not eating food, chewing gum, drinking beverages, or using tobacco products...

2013-04-01

241

21 CFR 111.10 - What requirements apply for preventing microbial contamination from sick or infected personnel...  

Code of Federal Regulations, 2011 CFR

...that may result in contamination any person who, by medical examination, the person's acknowledgement, or...contact surfaces are washed; (8) Not eating food, chewing gum, drinking beverages, or using tobacco products...

2011-04-01

242

21 CFR 111.10 - What requirements apply for preventing microbial contamination from sick or infected personnel...  

Code of Federal Regulations, 2010 CFR

...that may result in contamination any person who, by medical examination, the person's acknowledgement, or...contact surfaces are washed; (8) Not eating food, chewing gum, drinking beverages, or using tobacco products...

2010-04-01

243

Characterization of sea surface chemical contamination after shipping accidents.  

PubMed

A contamination survey was conducted after the beaching of the stricken cargo ship MSC Napoli in Lyme Bay on the south coast of Devon (UK). A grid of 22 coastal and offshore stations was sampled to investigate the extent of spilled oil and to screen for chemical contamination, as well as to evaluate the behavior of the oil at the air-sea interface. Samples were collected from the sea surface microlayer (SML) and from subsurface waters (SSW) at each station. The fuel oil spilled (IFO 380) was also analyzed. The determination of oil-related hydrocarbons (aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), terpanes, and steranes) and the screening for other harmful chemicals on the inventory of the MSC Napoli in the seawater samples, was performed by PTV-GC/ MS using large volume injection (LVI) techniques. Screening did not reveal the presence of any harmful chemicals other than petroleum-related compounds. Results afforded investigation of oil sources and spatial distributions of total PAH concentrations and enrichments in the sea surface microlayer (SML). Rather than a single source, oil fingerprinting analyses of the samples revealed a mixture of three types of oil: heavy fuel oil, lubricating oil, and a lighter oil (probably diesel oil). Enrichment factors (EF) in the SML (EF = C(SML)/C(SSW)) were calculated and, in the vicinity of the ship, approached 2000, declining with distance away from the wreck. These factors represent approximately a 1000-fold enrichment over typical coastal total PAH enrichments in the SML and reflected a clear petrogenic origin of the contamination (as demonstrated, for example, by a Fl/Pgamma ratio < 1). In addition, the spatial transport and fate (i.e., air-sea exchange processes and water column diffusion) of the oil-related hydrocarbons in the sea surface were investigated. Essentially, near the wreck, the SML was highly enriched in oil forming a visible sheen, both disrupting the normal air-seawater exchange processes and generating a downward diffusion flux of contaminants from the SML to the SSW. This was reflected by a higher occurrence of naphthalene relative to alkyl-naphthalenes in the SSW compared to the SML. The higher concentrations and different sources of oil found in the SML in comparison to those found in the SSW indicate that, if only subsurface water samples are investigated in isolation, the true extent and impact of a spill could be underestimated. It is important to simultaneously evaluate contamination in the sea surface during emergency response. PMID:18504953

Guitart, Carlos; Frickers, Patricia; Horrillo-Caraballo, Jose; Law, Robin J; Readman, James W

2008-04-01

244

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

245

Evaluation of imputation methods for microbial surface water quality studies.  

PubMed

Longitudinal studies of microbial water quality are subject to missing observations. This study evaluates multiple imputation (MI) against data deletion, mean or median imputation for replacing missing microbial water quality data. The specific context is data collected in Chicago Area Waterway System (2007-2009), where 45% of Escherichia coli and 53% of enterococci densities were missing owing to sample analysis deficiencies. Imputation methods were compared performing a simulation study using complete observations with introduced missing values and subsequently compared with the original data with missing observations. Coefficients for E. coli densities in linear regression models predicting somatic coliphages density show that MI introduces the least bias among other methods while controlling Type I error. Further exploration of utilizing different MI implementations is recommended to address the influence of missing percentage on MI performance and to explore sensitivity to the degree of violation of the missing completely at random assumption. PMID:24705739

Nieh, Chiping; Dorevitch, Samuel; Liu, Li C; Jones, Rachael M

2014-05-01

246

Effect of surface treatment on the biocompatibility of microbial polyhydroxyalkanoates  

Microsoft Academic Search

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

Xianshuang Yang; Kai Zhao; Guo-Qiang Chen

2002-01-01

247

Contamination of surface, ground, and drinking water from pharmaceutical production.  

PubMed

Low levels of pharmaceuticals are detected in surface, ground, and drinking water worldwide. Usage and incorrect disposal have been considered the major environmental sources of these microcontaminants. Recent publications, however, suggest that wastewater from drug production can potentially be a source of much higher concentrations in certain locations. The present study investigated the environmental fate of active pharmaceutical ingredients in a major production area for the global bulk drug market. Water samples were taken from a common effluent treatment plant near Hyderabad, India, which receives process water from approximately 90 bulk drug manufacturers. Surface water was analyzed from the recipient stream and from two lakes that are not contaminated by the treatment plant. Water samples were also taken from wells in six nearby villages. The samples were analyzed for the presence of 12 pharmaceuticals with liquid chromatography-mass spectrometry. All wells were determined to be contaminated with drugs. Ciprofloxacin, enoxacin, cetirizine, terbinafine, and citalopram were detected at more than 1 microg/L in several wells. Very high concentrations of ciprofloxacin (14 mg/L) and cetirizine (2.1 mg/L) were found in the effluent of the treatment plant, together with high concentrations of seven additional pharmaceuticals. Very high concentrations of ciprofloxacin (up to 6.5 mg/L), cetirizine (up to 1.2 mg/L), norfloxacin (up to 0.52 mg/L), and enoxacin (up to 0.16 mg/L) were also detected in the two lakes, which clearly shows that the investigated area has additional environmental sources of insufficiently treated industrial waste. Thus, insufficient wastewater management in one of the world's largest centers for bulk drug production leads to unprecedented drug contamination of surface, ground, and drinking water. This raises serious concerns regarding the development of antibiotic resistance, and it creates a major challenge for producers and regulatory agencies to improve the situation. PMID:19449981

Fick, Jerker; Söderström, Hanna; Lindberg, Richard H; Phan, Chau; Tysklind, Mats; Larsson, D G Joakim

2009-12-01

248

Use of Hydrostatic Pressure for Inactivation of Microbial Contaminants in Cheese  

PubMed Central

The objective of this study was to determine the effect of high pressure (HP) on the inactivation of microbial contaminants in Cheddar cheese (Escherichia coli K-12, Staphylococcus aureus ATCC 6538, and Penicillium roqueforti IMI 297987). Initially, cheese slurries inoculated with E. coli, S. aureus, and P. roqueforti were used as a convenient means to define the effects of a range of pressures and temperatures on the viability of these microorganisms. Cheese slurries were subjected to pressures of 50 to 800 MPa for 20 min at temperatures of 10, 20, and 30°C. At 400 MPa, the viability of P. roqueforti in cheese slurry decreased by >2-log-unit cycles at 10°C and by 6-log-unit cycles at temperatures of 20 and 30°C. S. aureus and E. coli were not detected after HP treatments in cheese slurry of >600 MPa at 20°C and >400 MPa at 30°C, respectively. In addition to cell death, the presence of sublethally injured cells in HP-treated slurries was demonstrated by differential plating using nonselective agar incorporating salt or glucose. Kinetic experiments of HP inactivation demonstrated that increasing the pressure from 300 to 400 MPa resulted in a higher degree of inactivation than increasing the pressurization time from 0 to 60 min, indicating a greater antimicrobial impact of pressure. Selected conditions were subsequently tested on Cheddar cheese by adding the isolates to cheese milk and pressure treating the resultant cheeses at 100 to 500 MPa for 20 min at 20°C. The relative sensitivities of the isolates to HP in Cheddar cheese were similar to those observed in the cheese slurry, i.e., P. roqueforti was more sensitive than E. coli, which was more sensitive than S. aureus. The organisms were more sensitive to pressure in cheese than slurry, especially with E. coli. On comparison of the sensitivities of the microorganisms in a pH 5.3 phosphate buffer, cheese slurry, and Cheddar cheese, greatest sensitivity to HP was shown in the pH 5.3 phosphate buffer by S. aureus and P. roqueforti while greatest sensitivity to HP by E. coli was exhibited in Cheddar cheese. Therefore, the medium in which the microorganisms are treated is an important determinant of the level of inactivation observed. PMID:11055940

O'Reilly, Ciara E.; O'Connor, Paula M.; Kelly, Alan L.; Beresford, Thomas P.; Murphy, Patrick M.

2000-01-01

249

Test of opticlean strip coating material for removing surface contamination.  

PubMed

The strip coating material, Opticlean, which has been reformulated, has been shown to remove 1-5-microm-diameter particles as well as contamination remaining from previous drag wipe cleaning on a used silicon wafer. In addition, no residue that produced scattering was found on a fresh silicon wafer when Opticlean was applied and then stripped off. The total integrated scattering technique used for the measurements could measure scattering levels of He-Ne laser light as low as a few ppm (parts in 10(6)), corresponding to a surface roughness of <1 A rms. PMID:18345196

Bennett, J M; Rönnow, D

2000-06-01

250

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

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.

Lorah, Michelle M.; Clark, Jeffrey S.

1996-01-01

251

Geochemistry and microbial diversity of a trichloroethene-contaminated Superfund site undergoing intrinsic in situ reductive dechlorination  

Microsoft Academic Search

This study explored the geochemistry and microbial diversity of a Superfund site containing trichloroethene (TCE) and an unusual co-pollutant, tetrakis(2-ethylbutoxy)silane. Geochemical analysis of contaminated groundwater indicated subsurface anaerobiosis, reductive dechlorination of TCE to predominantly cis-1,2-dichloroethene, and (transient) accumulation of 2-ethylbutanol and 2-ethylbutyrate as a result of tetrakis(2-ethylbutoxy)silane breakdown. Comparative analysis of 106 16S rDNA and 61 16S–23S rDNA intergenic spacer

Mary Lowe; Eugene L. Madsen; Karen Schindler; Courtney Smith; Scott Emrich; Frank Robb; Rolf U. Halden

2002-01-01

252

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

E-print Network

Natural arsenic contamination of Holocene alluvial aquifers by linked tectonic, weathering tectonic, geochemical, and biologic processes lead to natural arsenic contamination of groundwater are commonly found a long distance from their ultimate source of arsenic, where chemical weathering of As

Fayek, Mostafa

253

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

National Technical Information Service (NTIS)

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 act...

S. M. Pfiffner, A. V. Palumbo, J. F. McCarthy, T. Gibson

1996-01-01

254

The Effects of Microbial Population on Phytoremediation of Petroleum Contaminated Soils Using Tall Fescue  

Microsoft Academic Search

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

JAHANGIR ABEDI-KOUPAI; REZA EZZATIAN; MANOUCHEHR VOSSOUGHI-SHAVARI; SOHEILA YAGHMAEI; MEHDI BORGHEI

255

Quantitative microbial monitoring in a dental office  

Microsoft Academic Search

The aim of this study was to evaluate the environmental pollution before and after dental procedures (during one year) in a dental office in which a system of air filtration was effective and suitable procedures of microbial controls were routinely applied for instruments and small surfaces. The air contamination was evaluated during one year by the ‘plate’ method (Air Microbial

L Cellini; E Di Campli; M Di Candia; G Chiavaroli

2001-01-01

256

Estimation of Microbial Contamination of Food from Prevalence and Concentration Data: Application to Listeria monocytogenes in Fresh Vegetables?  

PubMed Central

A normal distribution and a mixture model of two normal distributions in a Bayesian approach using prevalence and concentration data were used to establish the distribution of contamination of the food-borne pathogenic bacteria Listeria monocytogenes in unprocessed and minimally processed fresh vegetables. A total of 165 prevalence studies, including 15 studies with concentration data, were taken from the scientific literature and from technical reports and used for statistical analysis. The predicted mean of the normal distribution of the logarithms of viable L. monocytogenes per gram of fresh vegetables was ?2.63 log viable L. monocytogenes organisms/g, and its standard deviation was 1.48 log viable L. monocytogenes organisms/g. These values were determined by considering one contaminated sample in prevalence studies in which samples are in fact negative. This deliberate overestimation is necessary to complete calculations. With the mixture model, the predicted mean of the distribution of the logarithm of viable L. monocytogenes per gram of fresh vegetables was ?3.38 log viable L. monocytogenes organisms/g and its standard deviation was 1.46 log viable L. monocytogenes organisms/g. The probabilities of fresh unprocessed and minimally processed vegetables being contaminated with concentrations higher than 1, 2, and 3 log viable L. monocytogenes organisms/g were 1.44, 0.63, and 0.17%, respectively. Introducing a sensitivity rate of 80 or 95% in the mixture model had a small effect on the estimation of the contamination. In contrast, introducing a low sensitivity rate (40%) resulted in marked differences, especially for high percentiles. There was a significantly lower estimation of contamination in the papers and reports of 2000 to 2005 than in those of 1988 to 1999 and a lower estimation of contamination of leafy salads than that of sprouts and other vegetables. The interest of the mixture model for the estimation of microbial contamination is discussed. PMID:17098926

Crepet, Amelie; Albert, Isabelle; Dervin, Catherine; Carlin, Frederic

2007-01-01

257

Microbial Contamination of Allende and Murchison Carbonaceous Chondrites; Developing a Protocol for Life Detection in Extraterrestrial Materials Using Biotechnology  

NASA Technical Reports Server (NTRS)

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.

Steele, A.; Whitby, C.; Griffin, C.; Toporski, J. K. W.; Westall, F.; Saunders, J. R.; McKay, D. S.

2001-01-01

258

Investigating the Influence of Remedial Capping on the Hydrological, Geochemical, and Microbial Processes that Control Subsurface Contaminant Migration at WAG 5 on the Oak Ridge Reservation: Implications toward Long-Term Stewardship  

NASA Astrophysics Data System (ADS)

The following research investigated the effectiveness of an aggressive, large scale remedial action that is occurring to subsurface waste trenches containing radioactive and organic waste at the Oak Ridge National Laboratory. The site is being remediated as one of the top cleanup prioritization for the Oak Ridge Accelerated Remediation endeavor. Site landlords, Bechtel Jacobs Co., LLC (BJC) are installing a minimal RCRA cap with the primary objective of controlling the infiltration of storm water into the hundreds of unconfined waste trenches containing radioactive and organic waste. The site now offers a unique scientific opportunity to track the kinetic evolution of post-cap processes influencing contaminant migration and immobilization, because we have many years of pre-cap coupled processes information and knowledge. Since the cap is certain to disrupt the near steady-state contaminant discharge profiles that have existed for many years from the site, we have been quantifying the influence of post-cap hydrological, geochemical, and microbial processes on contaminant discharge as a function of scale and time in an effort to assess local-scale cap influences versus regional scale groundwater flow influences on contaminant discharge. We have been allowed to maintain numerous groundwater monitoring wells at a field site and these have a rich historical data set with regard to hydrology, geochemistry, microbiology, and contaminant flux. Our objectives are to investigate cap induced changes in (1) groundwater and surface hydrology and contaminant flux, (2) geochemistry and contaminant speciation, and (3) microbial community structure and organic contaminant degradation and inorganic contaminant immobilization. Our approach monitors coupled processes during base-flow and during storm events in both the groundwater and surface water discharge from the site and the surrounding watershed. Pre- and post-cap data will than be modeled with a multiprocess, multicomponent, transport model which is linked to pre- and post-cap surface water hydrograph analysis from the site and the surrounding watershed. Our goal is to provide an improved fundamental understanding of the long-term fate and transport of contaminants and an improved ability to predict system response to remedial actions. The experimental and numerical results from this investigation will provide knowledge and information in previously unexplored areas of cap performance with regard to coupled hydrology, geochemistry, microbiology, and contaminant flux in humid regimes. The products will support DOE's mission of long-term stewardship of contaminated environments and be transferable to other site where similar remediation exists or is planned.

Jardine, P. M.; Mehlhorn, T. L.

2006-05-01

259

Filtration of contaminated suspended solids for the treatment of surface water  

Microsoft Academic Search

As few technologies exist worldwide for the treatment of contaminated surface water, a new approach is currently under development consisting of an in situ water treatment system based on a floating filtration process for adsorbed contaminants such as heavy metals. Laboratory filtration tests were performed for the removal of contaminated suspended solids (SS) from surface water. SS, chemical oxygen demand

Catherine N. Mulligan; Neginmalak Davarpanah; Masaharu Fukue; Tomohiro Inoue

2009-01-01

260

Interpretation of pesticide contamination monitoring data in surface water in France  

E-print Network

Interpretation of pesticide contamination monitoring data in surface water in France Christine requires a monitoring of pesticide contamination in surface water. In France, 15 million analyses have been of drinking water standards, or specific knowledge of pesticide contamination) and area of concern, leading

Paris-Sud XI, Université de

261

Environmental proteomics reveals early microbial community responses to biostimulation at a uranium- and nitrate-contaminated site.  

PubMed

High-performance MS instrumentation coupled with improved protein extraction techniques enables 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 the Firmicutes dominated the biostimulated aquifer community. Proteome characterization revealed distinct differences between the microbial biomass collected from groundwater influenced by biostimulation and groundwater collected upgradient of the EVO injection points. In particular, proteins involved in ammonium assimilation, EVO degradation, and polyhydroxybutyrate granule formation were prominent following biostimulation. Interestingly, the atypical NosZ of Dechloromonas spp. was highly abundant, suggesting active nitrous oxide (N2 O) respiration. c-Type cytochromes were barely detected, as was citrate synthase, a biomarker for hexavalent uranium reduction activity, suggesting that uranium reduction has not commenced 4 days post EVO amendment. Environmental metaproteomics identified microbial community responses to biostimulation and elucidated active pathways demonstrating the value of this technique as a monitoring tool and for complementing nucleic acid-based approaches. PMID:23894087

Chourey, Karuna; Nissen, Silke; Vishnivetskaya, Tatiana; Shah, Manesh; Pfiffner, Susan; Hettich, Robert L; Löffler, Frank E

2013-10-01

262

GeoChip-based analysis of functional microbial communities in a bioreduced uranium-contaminated aquifer during reoxidation by oxygen  

SciTech Connect

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.

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

263

Establishing benchmark rates of microbial and bacterial endotoxin contamination for radiopharmaceuticals compounded in commercial nuclear pharmacy settings.  

PubMed

The objective of this study was to establish benchmark rates for microbial and bacterial endotoxin contamination rates for radiopharmaceutical preparations compounded in commercial nuclear pharmacies. Radiopharmaceutical samples were obtained between November 2006 and June 2010 from seven commercial nuclear pharmacies. Preparations were compounded per the compounding protocols of each radiopharmacy, and each kit was used for unit-dose dispensing of patient-specific doses. Samples for testing were withdrawn after unit doses were dispensed. Sterility testing was performed on each radiopharmaceutical sample and incubated at appropriate temperatures for 14 days. A sample of the radiopharmaceutical was also used to complete limulus amebocyte lysate-based bacterial endotoxin testing. Over the course of the study, 1516 radiopharmaceutical samples from 16 different radiopharmaceutical preparations, including eluates from radionuclide generators, were tested for sterility and bacterial endotoxicity. For sterility testing, 13 of the 1516 samples (0.86%) showed evidence of growth in the testing media, indicating the presence of microbes in the tested sample. For bacterial endotoxin testing, 4 or 1492 samples (0.27% showed formation of gel clots, indicating the presence of bacterial endotoxins in the sample. The microbial and bacterial endotoxin contamination rates of aseptically compounded radiopharmaceuticals compounded in a commercial nuclear pharmacy environment are extremely low. The results of this study show the high level of safety and quality that is provided when obtaining radiopharmaceutical doses that are compounded and dispensed from a commercial nuclear pharmacy. PMID:23696179

Weatherman, Kara D; Augustine, Samuel; Christoff, Jeffrey; Galbraith, Wendy

2013-01-01

264

GeoChip-based analysis of functional microbial communities during the reoxidation of a bioreduced uranium-contaminated aquifer  

SciTech Connect

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.

Van Nostrand, Joy [University of Oklahoma, Norman; Wu, Weimin [ORNL; Wu, Liyou [University of Oklahoma, Norman; Deng, Ye [University of Oklahoma; Carley, Jack M [ORNL; Carroll, Sue L [ORNL; He, Zhili [University of Oklahoma; Gu, Baohua [ORNL; Luo, Jian [ORNL; Criddle, Craig [ORNL; Watson, David B [ORNL; Jardine, Philip M [ORNL; Marsh, Terence [Michigan State University, East Lansing; Tiedje, James [Michigan State University, East Lansing; Hazen, T. C. [Lawrence Berkeley National Laboratory (LBNL); Zhou, Jizhong [University of Oklahoma, Norman

2009-01-01

265

In situ assessment of microbial sulfate reduction in a petroleum-contaminated aquifer using push–pull tests and stable sulfur isotope analyses  

Microsoft Academic Search

Anaerobic microbial activities such as sulfate reduction are important for the degradation of petroleum hydrocarbons (PHC) in contaminated aquifers. The objective of this study was to evaluate the feasibility of single-well push–pull tests in combination with stable sulfur isotope analyses for the in situ quantification of microbial sulfate reduction. A series of push–pull tests was performed in an existing monitoring

M. H. Schroth; J. Kleikemper; C. Bolliger; S. M. Bernasconi; J. Zeyer

2001-01-01

266

Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces  

SciTech Connect

The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. The technology shows a great potential for accelerating the clean-up effort for the equipment and structures contaminated with radioactive materials within the DOE complex. The viability of this technology has been demonstrated by selectively and rapidly stripping uranium from stainless steel surfaces at low temperature. Studies on uranium oxide have shown that etch rates of 4.0 microns per minute can be achieved at temperature below 473 K. Over the past three years, we have made numerous improvements in the design of the atmospheric pressure plasma source. We are now able to scale up the plasma source to treat large surface areas.

Robert F. Hicks; Hans W. Herrmann

2003-12-15

267

Analysis of Genesis Sample Surface Contamination by Total Reflection X-Ray Fluorescence Spectrometry  

NASA Astrophysics Data System (ADS)

Laboratory based TXRF has been used to analyze Genesis flight samples for surface contamination. After initial cleaning substantial contaminations remained but additional acid cleaning could remove most of these.

Schmeling, M.

2010-03-01

268

Remediation aspect of microbial changes of plant rhizosphere in mercury contaminated soil  

Microsoft Academic Search

Phytoremediation, an approach that uses plants to remediate contaminated soil through degradation, stabilization or accumulation,\\u000a may provide an efficient solution to some mercury contamination problems. This paper presents growth chamber experiments that\\u000a tested the ability of plant species to stabilize mercury in soil. Several indigenous herbaceous species and Salix viminalis were grown in soil collected from a mercury-contaminated site in

Aleksandra Sas-Nowosielska; Regina Galimska-Stypa; Rafa? Kucharski; Urszula Zielonka; Eugeniusz Ma?kowski; Laymon Gray

2008-01-01

269

Assessment of the microbial diversity at the surface of Livarot cheese using culture-1 dependent and independent approaches2  

E-print Network

1 Assessment of the microbial diversity at the surface of Livarot cheese using culture-1 dependent2011 Author manuscript, published in "International Journal of Food Microbiology 133, 1-2 (2009) 31-37" DOI : 10.1016/j.ijfoodmicro.2009.04.020 #12;2 ABSTRACT11 12 The microbial diversity of the surface

Boyer, Edmond

270

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

PubMed Central

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

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

271

Microbial metabolism and community structure in response to bioelectrochemically enhanced remediation of petroleum hydrocarbon-contaminated soil.  

PubMed

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

Lu, Lu; Huggins, Tyler; Jin, Song; Zuo, Yi; Ren, Zhiyong Jason

2014-04-01

272

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

SciTech Connect

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.

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

273

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

SciTech Connect

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.

Van Nostrand, Dr. Joy D. [Oklahoma University; Wu, Liyou [University of Oklahoma, Norman; Wu, Weimin [Stanford University; Huang, Zhijian [Sun Yat-Sen University, Guangzhou, China; Gentry, Terry J [ORNL; Deng, Ye [University of Oklahoma; Carley, Jack M [ORNL; Carroll, Sue L [ORNL; He, Zhili [University of Oklahoma; Gu, Baohua [ORNL; Luo, Jian [Georgia Institute of Technology; Criddle, Craig [Stanford University; Watson, David B [ORNL; Jardine, Philip M [ORNL; Marsh, Terence [Michigan State University, East Lansing; Tiedje, James [Michigan State University, East Lansing; Hazen, Terry [Lawrence Berkeley National Laboratory (LBNL); Zhou, Jizhong [University of Oklahoma, Norman

2011-01-01

274

Microbial Specificity of Metallic Surfaces Exposed to Ambient Seawater  

PubMed Central

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

Zaidi, B. R.; Bard, R. F.; Tosteson, T. R.

1984-01-01

275

Microbial biofilm detection on food contact surfaces by macro-scale fluorescence imaging  

Microsoft Academic Search

Hyperspectral fluorescence imaging methods were utilized to evaluate the potential detection of pathogenic bacterial biofilm formations on five types of food contact surface materials: stainless steel, high-density polyethylene (HDPE), plastic laminate (Formica), and two variations of polished granite. The main objective of this study was to determine a minimal number of spectral fluorescence bands suitable for detecting microbial biofilms on

Won Jun; Moon S. Kim; Byoung-Kwan Cho; Patricia D. Millner; Kuanglin Chao; Diane E. Chan

2010-01-01

276

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 ...

277

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

Microsoft Academic Search

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

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

2009-01-01

278

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...

279

Dental handpiece contamination: a proteomics and surface analysis approach.  

PubMed

Dental handpieces (DHPs) become biofouled internally with patient derived material that is difficult to access for removal and inactivation. This study undertook a quantitative and qualitative investigation of protein contamination of internal components from three different types of DHP: the turbine, slow speed contra-angle and surgical. Eluates from the high speed turbine, low speed spray channels and surgical gear were assayed for protein using an orthophthaldehyde assay. Eluates concentrated by Amicon ultrafiltration were also analysed by SDS-PAGE, mass spectroscopy, Western blotting and ELISA. The surfaces of handpiece components were also investigated by SEM, EFSCAN and EDAX microscopy. Surgical gears contained highest levels of protein (403??g), followed by low speed spray channels (17.7??g) and the high speed turbine (<5??g). Mass spectroscopy of surgical gears demonstrated mostly serum derived proteins. Decontamination of the DHPs using an automated washer disinfector and handpiece irrigator showed a significant reduction in residual protein levels. PMID:24138163

Smith, Andrew; Smith, Gordon; Lappin, David F; Baxter, Helen C; Jones, Anita; Baxter, Robert L

2014-01-01

280

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

Microsoft Academic Search

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

Rosa Bellas; Ma Carmen Leirós; Fernando Gil-Sotres; Carmen Trasar-Cepeda

2010-01-01

281

Microbial Dynamics during Bioremediation of a Crude Oil-Contaminated Coastal Wetland  

Microsoft Academic Search

In 1996, a controlled crude oil application was conducted at a Texas intertidal, coastal wetland to determine the effectiveness of two biostimulation treatments in these sensitive areas. An inorganic nutrient treatment and inorganic nutrient plus a potential electron acceptor (nitrate) treatment were examined. As part of this research, polycyclic aromatic hydrocarbon (PAH)-degrading, aliphatic-degrading, and total heterotrophic microbial numbers were monitored.

Richard T. Townsend; James S. Bonner; Robin L. Autenrieth

2000-01-01

282

Soil microbial response during the phytoremediation of a PAH contaminated soil  

Microsoft Academic Search

The aim of this trial was to quantify and compare the responses of soil microbial communities during the phytoremediation of polycyclic aromatic hydrocarbons (PAHs) in a laboratory trial. The experiment was conducted in 1-kg pots and planted treatments consisted of a mixed ryegrass (Lolium perenne) and white clover (Trifolium repens) sward together with a rhizobial inoculum (Rhizobium leguminosarum bv. trifolii).

D. L. Johnson; D. R. Anderson; S. P. McGrath

2005-01-01

283

Microbial community dynamics during acetate biostimulation of RDX-contaminated groundwater.  

PubMed

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

Livermore, Joshua A; Jin, Yang Oh; Arnseth, Richard W; Lepuil, Michael; Mattes, Timothy E

2013-07-16

284

AUTOMATED RESPIROMETER METHOD FOR MICROBIAL TOXICITY ASSESSMENT OF LOW-LEVEL ZINC CONTAMINATION IN SOIL  

EPA Science Inventory

Zinc is an essential trace element for all living organisms including humans. ecause microbial-based toxicity approaches to assess the changes in ecosystem processes are not well defined for soil application, this laboratory has developed an automated respirometer capable of meas...

285

Bacterial communities of surface and deep hydrocarbon-contaminated waters of the Deepwater Horizon oil spill  

NASA Astrophysics Data System (ADS)

We performed a 16S rRNA gene sequencing survey of bacterial communities within oil-contaminated surface water, deep hydrocarbon plume water, and deep water samples above and below the plume to determine spatial and temporal patterns of oil-degrading bacteria growing in response to the Deepwater Horizon oil leak. In addition, we are reporting 16S rRNA sequencing results from time series incubation, enrichment and cultivation experiments. Surface oil slick samples were collected 3 nautical miles from ground zero, (5/6/10, RV Pelican) and were added to uncontaminated surface water (collected within a 30 nautical mile radius of ground zero, 5/6/10 - 5/9/10, RV Pelican). This mixture was incubated for 20 days in a rolling bottle at 25°C. 16S rRNA clone libraries from marine snow-like microbial flocs that had formed during the incubation yielded a highly diverse bacterial community, predominately composed of the Alpha- and Gammaproteobacteria, and a smaller number of Planktomycetes and other bacterial lineages. The most frequently recovered proteobacterial sequences were closely related to cultured species of the genus Cycloclasticus, specialists in aerobic oxidation of aromatic hydrocarbons. These time series incubation results will be compared to the microbial community structure of contaminated surface water, sampled on the same cruise with RV Pelican (5/6/10-5/9/10) and frozen immediately. Stable isotope probing (SIP) experiments with C13-labelled alkanes and polycyclic aromatic substrates and gulf water samples have yielded different enrichments. With naphthalene, predominantly Alteromonas-related clones and a smaller share of Cycloclasticus clones were recovered; phenanthrene yielded predominantly clones related to Cycloclasticus, and diverse other Gamma- and Alphaproteobacteria. Analyses of SIP experiments with hexadecane are in progress. The microbial community composition of the deep hydrocarbon plume was characterized using water column profile samples taken with RV Walton Smith on May 30, at station WS 46 near the leak (28°N659.35; 88°W.43498). Water was collected and filtered from above the plume (800 m), within the plume (1170 m and 1210 m) and below the plume (1320 m) as indicated by Color Dissolved Organic Matter (CDOM) measurements. Clone libraries of both plume samples were dominated by a cluster of closely related 16S rRNA clones within the Oceanospirillales. The closest relatives were aerobic alkane oxidizers of the genera Oleispira and Thalassolituus. In contrast, the water samples above and below the plume showed distinct, diverse bacterial communities that lacked the characteristic clones of the hydrocarbon plume. Analysis of additional water samples from different locations and time points will further resolve spatial and temporal dynamics of oil degrading microbes in the water column. Thus far, our results indicate a stratified bacterial community in the oil-polluted water column with distinct types of oil-degrading bacteria in surface oil slicks and finely dispersed deepwater plumes.

Yang, T.; Nigro, L. M.; McKay, L.; Ziervogel, K.; Gutierrez, T.; Teske, A.

2010-12-01

286

Comparison of microbial numbers and enzymatic activities in surface soils and subsoils using various techniques  

Microsoft Academic Search

Knowledge of microbial numbers and activity in subsoils is essential for understanding the transformation and downward movement of natural and synthetic organics. Soil cores were taken from two soil profiles (surface textures: silty clay loam and loamy sand), and samples extracted from the 0–30cm (surface), 1.0–1.3m (mid) and 2.7–3.0m (deep; clay) and 3.9–4.2m (deep; sand) layers. A variety of soil

J. P Taylor; B Wilson; M. S Mills; R. G Burns

2002-01-01

287

Effects of heavy metal contamination and remediation on soil microbial communities in the vicinity of a zinc smelter as indicated by analysis of microbial community phospholipid fatty acid profiles  

Microsoft Academic Search

Heavy metal contamination in an area immediately surrounding a zinc smelter has resulted in destruction of over 485 hectares of forest. The elevated levels of heavy metals in these soils have had significant impacts on the population size and overall activity of the soil microbial communities. Remediation of these soils has resulted in increases in indicators of biological activity and viable

John J. Kelly; Max M. Häggblom; Robert L. Tate

2003-01-01

288

Inter-electrode spacing of surface EMG sensors: Reduction of crosstalk contamination during voluntary contractions  

E-print Network

Inter-electrode spacing of surface EMG sensors: Reduction of crosstalk contamination during-electrode spacing on the degree of crosstalk contamination in surface electromyographic (sEMG) signals Elsevier Ltd. All rights reserved. 1. Introduction Surface electromyographic (sEMG) signals detected

De Luca, Carlo J.

289

Comparison of three 15N methods to correct for microbial contamination when assessing in situ protein degradability of fresh forages.  

PubMed

The use of stable (15)N as a marker to determine microbial contamination in nylon bag incubation residues to estimate protein degradability was investigated. Three methods using (15)N were compared: (15)N-labeled forage (dilution method, LF), (15)N enrichment of rumen solids-associated bacteria (SAB), and (15)N enrichment of rumen liquid-associated bacteria (LAB). Herbage from forages differing in protein and fiber contents (early-cut Italian ryegrass, late-cut Italian ryegrass, and red clover) were freeze-dried and ground and then incubated in situ in the rumen of 3 steers for 3, 6, 12, 24, and 48 h using the nylon bag technique. The (15)N-labeled forages were obtained by fertilizing the plots where herbage was grown with (15)NH4 (15)NO3. Unlabeled forages (obtained from plots fertilized with NH4NO3) were incubated at the same time that ((15)NH4)2SO4 was continuously infused into the rumen of the steers, and then pellets of labeled SAB and LAB were isolated by differential centrifugation of samples of ruminal contents. The proportion of bacterial N in the incubation residues increased from 0.09 and 0.45 g bacterial N/g total N at 3 h of incubation to 0.37 and 0.85 g bacterial N/g total N at 48 h of incubation for early-cut and late-cut ryegrass, respectively. There were differences (P < 0.001) between uncorrected N degradability values and those corrected for microbial contamination with all of the methods. Apparent N degradability of the low-N, high-fiber forage (late-cut ryegrass) was 0.51, whereas the corrected values were 0.85, 0.84, and 0.77 for the LF, SAB, and LAB methods, respectively. With early-cut ryegrass and red clover, the differences between uncorrected and corrected values ranged between 6% and 13%, with small differences among the labeling methods. Generally, methods using labeled forage or labeled SAB and LAB provided similar corrected degradability values. The accuracy in estimating the extent of degradation of protein in the rumen from in situ disappearance curves is improved when values are corrected for microbial contamination of the bag residue. PMID:25349353

Kamoun, M; Ammar, H; Théwis, A; Beckers, Y; France, J; López, S

2014-11-01

290

Critical contaminant/critical pathway analysis - surface water transport for nonradioactive contaminants  

SciTech Connect

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 noncancer hazard indices vary from 6.E-02 to 1.E-01. The critical contaminants were ranked based on their cancer risks and chronic noncarcinogenic hazard quotients. For cancer risks, the critical contaminants released from SRS outfalls are arsenic, tetrachloroethylene, and benzene. For chronic noncarcinogenic risks, the critical contaminants released from srs outfalls are cadmium, arsenic, silver, chromium, mercury, selenium, nitrate, manganese, zinc, nickel, uranium, barium, copper, tetrachloroethylene, cyanide, and phenol. The critical pathways in decreasing risk order are ingestion of contaminated fish, ingestion of drinking water and dermal contact with contaminants in water while swimming.

Chen, Kuo-Fu

1996-11-01

291

A comparison of DNA profiling techniques for monitoring nutrient impact on microbial community composition during bioremediation of petroleum-contaminated soils  

Microsoft Academic Search

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

DeEtta K Mills; Kristin Fitzgerald; Carol D Litchfield; Patrick M Gillevet

2003-01-01

292

Microbial Growth and Coexistence on Diffusion-limited Unsaturated Rough Surfaces  

NASA Astrophysics Data System (ADS)

Microbial activity in unsaturated soils plays an important role in biochemical nutrient cycling, bioremediation, and dispersal of pathogenic microorganisms. Quantitative description of microbial activity in unsaturated soils is hindered by complexity of pore space and hydration dynamics. Microbes in unsaturated soils live in an environment dominated by presence of numerous solid- and gas-liquid interfaces, where nutrient distribution and flux pathways are dynamically shaped by liquid configuration. We propose a model for considering effects of nutrient diffusive fluxes under various hydrations and pore space conditions on microbial growth and coexistence of two competing bacterial species. Simulation results show that hydration limitation to nutrient diffusive fluxes enhance microbial coexistence and are in good agreement with available experimental results. Effective nutrient diffusion coefficients on rough surfaces is significantly affected by liquid configuration and by connectivity (expressed as percolation probability) of the surface roughness network. The aqueous network is dynamically controlled by matric potential where effective diffusion coefficient varied from 0.46 mm2/hr to 0 and percolation probability varied from 0.76 to 0.21 when matric potential varies from -0.01 to -5 kPa, respectively. For matric potential values of -2.0 kPa and lower, two competing microbial species coexisted indefinitely supported by limited nutrient flux and within fragmented liquid clusters with percolation probability 0.37. Coexistence was limited to 90 hrs at -1.2 kPa with increasing percolation probability to 0.52 (effective diffusion coefficient of 0.19 mm2/hr). No coexistence was observed at matric potential of -0.01 kPa, the stronger species rapidly expanded and dominated the entire domain. Pore scale and roughness microhydrology may play an important role in the large microbial diversity found in soil.

Wang, G.; Or, D.

2009-04-01

293

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

E-print Network

into the subsurface from leaking landfills. Detecting leachate contamination using statistical techniques to industrial or hazardous waste dumping. As a result, municipal solid waste landfill (MSWLF) leachates municipal solid waste leachate, rich in nutrients and anthropogenic compounds, percolates

Vermont, University of

294

Epidemiological Investigation of Risk Factors for Microbial Contamination in Produce at the Preharvest Level  

E-print Network

monocytogenes, Salmonella, and Escherichia coli O157:H7. The overall objective of this dissertation was to study the risk factors for preharvest produce contamination with these three pathogens and generic Escherichia coli, as an indicator organism of fecal...

Park, Sangshin

2013-11-15

295

Remediation of uranium contaminated soils with bicarbonate extraction and microbial U(VI) reduction  

Microsoft Academic Search

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

Elizabeth J. P. Phillips; Edward R. Landa; Derek R. Lovley

1995-01-01

296

Metal-induced oxidative stress impacting plant growth in contaminated soil is alleviated by microbial siderophores  

Microsoft Academic Search

High levels of metals impede plant growth by affecting physiological processes. Siderophores are microbial Fe-chelators that, however, bind other metals. This study evaluated plant growth in a soil containing elevated levels of metals, including Al, Cu, Fe, Mn, Ni, and U, using Streptomyces-derived cell-free supernatant containing siderophores and auxins. Cowpea plants in the soil were treated with the culture filtrate.

Christian O. Dimkpa; Dirk Merten; Aleš Svatoš; Georg Büchel; Erika Kothe

2009-01-01

297

Impacts of Mineralogy and Competing Microbial Respiration Pathways on the Fate of Uranium in Contaminated Groundwater  

Microsoft Academic Search

This is a field-oriented project designed to elucidate the microbiological and geochemical factors controlling U(VI) reduction\\/immobilization in subsurface environments at the NABIR FRC. Efforts focused on acidic sediments, (1) to characterize the dominant minerals likely to limit U speciation, (2) to directly quantify microbial respiration processes controlling U subsurface chemistry, and (3) to identify and enumerate the responsible organisms. Results

Kostka; Joel E

2003-01-01

298

Mineralogical and Microbial Controls on Iron Reduction in a Contaminated Aquifer-Wetland System  

E-print Network

). Terminal electron acceptors (TEAs) are compounds that are accepted or utilized by microbes to obtain energy during the metabolism of an electron donor or carbon source. Studies have shown that through microbially mediated biological processes, as well... of Geochemica et Cosmochimica Acta. 2 When a microbe reduces iron (III) in conjunction with a carbon source, the carbon becomes oxidized into CO 2 , which is then utilized by the surrounding plants. Through this process, microbes are able to facilitate...

Howson, Andrea Melissa

2011-02-22

299

Microbial Communities in Long-Term Heavy Metal Contaminated Ombrotrophic Peats  

Microsoft Academic Search

High concentrations of heavy metals are known to be toxic to many soil organisms. The effects of long-term exposure to lower\\u000a levels of metals on the soil microbial community are, however, less well understood. The southern Pennines of the U.K. are\\u000a characterised by expanses of ombrotrophic peat soils that have experienced deposition of high levels of heavy metals since\\u000a the

Patricia E. Linton; Laura Shotbolt; Andrew D. Thomas

2007-01-01

300

Influence of difloxacin-contaminated manure on microbial community structure and function in soils  

Microsoft Academic Search

Difloxacin (DIF) belongs to the fluoroquinolones, a frequently detected group of antibiotics in the environment. It is excreted\\u000a in pig manure to a large extent and may consequently reach soils in potentially effective concentrations via manuring. The\\u000a aim of this study was to assess the effects of DIF-spiked manure on microbial communities and selected functions in soils\\u000a in a microcosm

Anja Kotzerke; Ute Hammesfahr; Kristina Kleineidam; Marc Lamshöft; Sören Thiele-Bruhn; Michael Schloter; Berndt-Michael Wilke

2011-01-01

301

Increased hand washing reduces influenza virus surface contamination in Bangkok households, 2009-2010  

PubMed Central

Within a hand-washing clinical trial, we evaluated factors associated with fomite contamination in households with an influenza-infected child. Influenza virus RNA contamination was higher in households with low absolute humidity and in control households, suggesting that hand washing reduces surface contamination. PMID:24373290

Levy, Jens W; Suntarattiwong, Piyarat; Simmerman, James M; Jarman, Richard G; Johnson, Kara; Olsen, Sonja J; Chotpitayasunondh, Tawee

2014-01-01

302

A new method for the determination of particulate contamination levels for surface cleanliness of fluid systems  

NASA Technical Reports Server (NTRS)

Levels of contamination in fluid systems can be determined by a definition of a particle by a mathematical model, a method for calculating the tolerance limits of contamination, and an estimation of the probability that the contamination on the surface will migrate with the fluid in the system.

1969-01-01

303

Increased hand washing reduces influenza virus surface contamination in Bangkok households, 2009-2010.  

PubMed

Within a hand-washing clinical trial, we evaluated factors associated with fomite contamination in households with an influenza-infected child. Influenza virus RNA contamination was higher in households with low absolute humidity and in control households, suggesting that hand washing reduces surface contamination. PMID:24373290

Levy, Jens W; Suntarattiwong, Piyarat; Simmerman, James M; Jarman, Richard G; Johnson, Kara; Olsen, Sonja J; Chotpitayasunondh, Tawee

2014-01-01

304

Molecular contamination study by interaction of a molecular beam with a platinum surface  

NASA Technical Reports Server (NTRS)

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.

Nuss, H. E.

1976-01-01

305

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

Distribution of Chromium Contamination and Microbial Activity in Soil Aggregates Tetsu K. Tokunaga on chromium diffusion and reduction in soil Steep gradients in oxygen concentrations and redox po.all of the soils. The small fraction of Cr(VI) remaining unreduced Chromium, used in a variety of industrial

Hazen, Terry

306

Composition and Diversity of Microbial Communities Recovered from Surrogate Minerals Incubated in an Acidic Uranium-Contaminated Aquifer  

PubMed Central

Our understanding of subsurface microbiology is hindered by the inaccessibility of this environment, particularly when the hydrogeologic medium is contaminated with toxic substances. In this study, surrogate geological media contained in a porous receptacle were incubated in a well within the saturated zone of a pristine region of an aquifer to capture populations from the extant communities. After an 8-week incubation, the media were recovered, and the microbial community that developed on each medium was compared to the community recovered from groundwater and native sediments from the same region of the aquifer, using 16S DNA coding for rRNA (rDNA)-based terminal restriction fragment length polymorphism (T-RFLP). The groundwater and sediment communities were highly distinct from one another, and the communities that developed on the various media were more similar to groundwater communities than to sediment communities. 16S rDNA clone libraries of communities that developed on particles of a specular hematite medium incubated in the same well as the media used for T-RFLP analysis were compared with those obtained from an acidic, uranium-contaminated region of the same aquifer. The hematite-associated community formed in the pristine area was highly diverse at the species level, with 25 distinct phylotypes identified, the majority of which (73%) were affiliated with the ?-Proteobacteria. Similarly, the hematite-associated community formed in the contaminated area was populated in large part by ?-Proteobacteria (62%); however, only 13 distinct phylotypes were apparent. The three numerically dominant clones from the hematite-associated community from the contaminated site were affiliated with metal- and radionuclide-tolerant or acidophilic taxa, consistent with the environmental conditions. Only two populations were common to both sites. PMID:15466548

Reardon, Catherine L.; Cummings, David E.; Petzke, Lynn M.; Kinsall, Barry L.; Watson, David B.; Peyton, Brent M.; Geesey, Gill G.

2004-01-01

307

Science and technology objective (STO) to develop tests for detecting microbial and chemical contaminants in food and water  

NASA Astrophysics Data System (ADS)

The assurance of safe food and water is paramount to the health and performance of the warfighter. Any technology to assess the chemical and microbial purity of food and water under field conditions must meet rigorous criteria: it must be readily portable, provide timely results (no more than 4 hours), have adequate sensitivity (1 cfu/100 mL for potable water), be compatible with military power sources, and be of complexity appropriate for operation by a Preventive Medicine Specialist. The nomination of an Army Science and Technology Objective (STO) leads to assessment of existing technologies and commercial products; identification of users, regulators and developers; definition of essential capabilities; and consideration of potential obstructions. The U.S. Army Center for Environmental Health Research has identified a number of technologies for detecting microbial contaminants in food and water and has pursued development of the more promising examples. This paper examines developmental risks in the context of the STO and offers some insight and strategies to manage them.

Knechtges, Paul L.; Gargan, Thomas P., II; Burrows, William D.

2002-02-01

308

Subsurface microbial community structure correlates with uranium redox phases during in situ field manipulation in a contaminated aquifer  

SciTech Connect

Long-term field manipulation experiments investigating the effects of subsurface redox conditions on the fate and transport of soluble uranium(VI) were conducted over a 3 year period at the Oak Ridge Integrated Field Research Center (OR-IFRC) in Oak Ridge, TN. In the highly contaminated source zone, introduction of ethanol to the subsurface stimulated native denitrifying, sulfate-reducing, iron-reducing and fermentative microorganisms and reduced U to below 0.03 mg/L. Subsequently, oxygen and nitrate were experimentally re-introduced into the subsurface to examine the potential for re-oxidation and re-mobilization of U(IV). Introduction of oxygen or nitrate caused changes in subsurface geochemistry and re-oxidation of U. After reoxidation, the subsurface experienced several months of starvation conditions before ethanol injection was restored to reduce the treatment zone. Subsurface microorganisms were characterized by community fingerprinting, targeted population analyses, and quantitative PCR of key functional groups in 50 samples taken during multiple phases of field manipulation. Statistical analysis confirmed the hypothesis that the microbial community would co-vary with the shifts in the subsurface geochemistry. The level of hydraulic connectivity of sampling wells to the injection well was readily tracked by microbial community analysis. We demonstrate quantitatively that specific populations, especially Desulfosporosinus, are heavily influenced by geochemical conditions and positively correlate with the immobilization of uranium. Following nitrate reoxidation, populations of Fe(II)-oxidizing, nitrate reducing organisms (Thiobacillus) showed an increase in relative abundance.

Kostka, Joel [Florida State University; Green, Stefan [Florida State University, Tallahassee; Wu, Wei-min [Stanford University; Criddle, Craig [Stanford University; Watson, David B [ORNL; Jardine, Philip M [ORNL

2009-07-01

309

Adsorption of a biosurfactant on surfaces to enhance the disinfection of surfaces contaminated with Listeria monocytogenes.  

PubMed

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

Meylheuc, T; Renault, M; Bellon-Fontaine, M N

2006-05-25

310

Effects of Heavy Metal Contamination upon Soil Microbes: Lead-induced Changes in General and Denitrifying Microbial Communities as Evidenced by Molecular Markers  

PubMed Central

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

Sobolev, Dmitri; Begonia, Maria F. T.

2008-01-01

311

Trimming and washing poultry carcass to reduce microbial contamination: A comparative study.  

PubMed

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

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

312

Wear testing of crosslinked polyethylene: wear rate variability and microbial contamination.  

PubMed

The wear performance of two types of crosslinked polyethylene (Marathon™ and XLK™, DePuy Synthes Inc., Warsaw, IN) was evaluated in a pin-on-disc wear tester, a hip wear simulator, and a knee wear simulator. Sodium azide was used as the microbial inhibitor in the calf serum-based lubricant. In the pin-on-disc wear tester, the Marathon wear rate of 5.33±0.54mm(3)/Mc was significantly lower (p=0.002) than the wear rate of 6.43±0.60mm(3)/Mc for XLK. Inversely, the Marathon wear rate of 15.07±1.03mm(3)/Mc from the hip wear simulator was 2.2-times greater than the XLK wear rate of 6.71±1.03mm(3)/Mc from the knee wear simulator. Differences in implant design, conformity, GUR type, and kinematic test conditions were suggested to account for the difference between the wear rates generated in the different types of wear testing apparati. In all wear tests, sodium azide was ineffective at inhibiting microbial growth in the lubricant. Eight different organisms were identified in the lubricant samples from the wear tests, which suggested the necessity of using an alternative, more effective microbial inhibitor. Careful sample preparation and thorough cleaning has shown to improve the consistency of the wear results. The wear rates generated in the hip and knee wear simulators closely reflected the wear behaviour of Marathon and XLK reported in published data that were tested under similar conditions. PMID:24607759

Brandt, J-M; Vecherya, A; Guenther, L E; Koval, S F; Petrak, M J; Bohm, E R; Wyss, U P

2014-06-01

313

Impacts of Mineralogy and Competing Microbial Respiration Pathways on the Fate of Uranium in Contaminated Groundwater  

SciTech Connect

This is a field-oriented project designed to elucidate the microbiological and geochemical factors controlling U(VI) reduction/immobilization in subsurface environments at the NABIR FRC. Efforts focused on acidic sediments, (1) to characterize the dominant minerals likely to limit U speciation, (2) to directly quantify microbial respiration processes controlling U subsurface chemistry, and (3) to identify and enumerate the responsible organisms. Results indicate that the activities and growth of bacteria are limited in this acidic subsurface. The relevant geochemical parameters have now been characterized, and respiration rates quantified.

Kostka, Joel E.

2003-06-01

314

Role of environmental fluctuations and microbial diversity in degradation of hydrocarbons in contaminated sludge.  

PubMed

Little is known about microbial communities involved in hydrocarbon degradation, whether it be their structural and functional diversity or their response to environmental constraints such as oxygen fluctuation. Here, current knowledge of the impact of diversity and redox oscillations upon ecosystem processes is reviewed. In addition, we present the main conclusions of our studies in this field. Oxic/anoxic oscillations had a strong impact upon bacterial community structures, influencing their ability to degrade hydrocarbons and their capacity to reduce hydrocarbon toxicity. Furthermore, a decrease in functional diversity has a strong impact on pollutant degradation. PMID:21530651

Cravo-Laureau, Cristiana; Hernandez-Raquet, Guillermina; Vitte, Isabelle; Jézéquel, Ronan; Bellet, Virginie; Godon, Jean-Jacques; Caumette, Pierre; Balaguer, Patrick; Duran, Robert

2011-11-01

315

Chemical and microbial contamination baseline in the Saguenay-St. Lawrence Marine Park (Eastern Canada): concentrations and fluxes from land-based sources.  

PubMed

Stretching halfway between the Canadian Great Lakes and the Atlantic Ocean, the Saguenay-St. Lawrence Marine Park is subject to environmental issues being exposed to untreated or uncontrolled point and non-point sources of anthropogenic contamination. This article provides a first estimation of chemical and microbial contamination entering the marine park from the discharges of local municipal effluents and the inputs of tributaries in the summer period. Suspended particulate matter (SPM), nutrients, particulate carbon (PC) and nitrogen, trace metals, and fecal coliform bacteria were determined in surface brackish waters at upstream boundaries, in freshwater of 11 tributaries, and in nine sewage effluents from small communities settled along the marine park. Most tributaries have SPM < 10 mg L(-1) and contributed to a total of ~47 tons day(-1), thus representing a small proportion of daily SPM transported by Saguenay River (200 tons day(-1)) and St. Lawrence River (6.3 × 10(3) tons day(-1)). As expected, untreated sewage effluents showed high fecal contamination (0.2-6.0 × 10(6) CFU 100 mL(-1)), high NO x levels (4-33 ?mol L(-1)) and high concentrations of particulate organic carbon (7-62 mg L(-1)). However, all tributaries had low coliforms (<230 CFU 100 mL(-1)), low PC (0.3-1.1 mg L(-1)), and low nutrients (NO(x) < 3.3 ?mol L(-1)), with the exception of the Moulin-à-Baude River, a small tributary (2.3 × 10(5) m(3) day(-1)) clearly contaminated by human activities. Detailed analysis of 14 metals and metalloids in SPM did not show any clear contamination trend between sewage effluents and tributaries, except for Grandes-Bergeronnes River, where most trace metals appeared to be greater than for other rivers. Regarding global inputs, results showed that despite their relatively high pollutants load, inputs from local sewages and small tributaries remained minor contributors compared with upstream inputs, i.e., Saguenay River and St. Lawrence River. However, we illustrate that some local hydrodynamic factors in bays and inlets must be taken into account when evaluating risks associated with sewage discharges. PMID:23695715

Lemaire, Nicolas; Pelletier, Émilien

2013-10-01

316

PARAMETERS OF TREATED STAINLESS STEEL SURFACES IMPORTANT FOR RESISTANCE TO BACTERIAL CONTAMINATION  

EPA Science Inventory

Use of materials that are resistant to bacterial contamination could enhance food safety during processing. Common finishing treatments of stainless steel surfaces used for components of poultry processing equipment were tested for resistance to bacterial attachment. Surface char...

317

Recovery of bacillus spore contaminants from rough surfaces: a challenge to space mission cleanliness control.  

PubMed

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

Probst, Alexander; Facius, Rainer; Wirth, Reinhard; Wolf, Marco; Moissl-Eichinger, Christine

2011-03-01

318

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

E-print Network

Available online 13 October 2012 Editorial handling by B. Ngwenya a b s t r a c t Soil collected from processing residue (COPR) is a globally wide- spread concern due to the risks associated with potentially contaminated with COPR is challenging, particularly because these sites are often in urban areas and date from

Burke, Ian

319

Microbial contamination of non-disposable instruments in otolaryngology out-patients.  

PubMed

Nosocomial infections are an important cause of morbidity and contaminated equipment may contribute to this. There has been little work concerning contamination of non-disposable equipment in Otolaryngology. This study investigates the efficacy of the cleaning regimen for non-disposable instruments in an Otolaryngology out-patients clinic. Instruments were swabbed before each clinic, when they had been autoclaved, then after use on patients, when they had been washed with detergent and chlorhexidine. Swabs of 86 instruments were cultured using standardized microbiological techniques. Fifteen instruments (17 per cent) were contaminated, most with coagulase negative staphylococci. Two specimens of Micrococcus luteus were cultured and one each of Pseudomonas aeruginosa, Acinetobacter lwoffii and Aureobacterium spp. Micrococcus luteus and coagulase negative staphylococci may represent skin contaminants, but Aureobacterium spp. and Acinetobacter lwoffii can be sources of nosocomial infection. Pseudomonas aeruginosa is a potentially serious pathogen and is implicated in the aetiology of otitis externa. These findings question the efficacy of the current cleaning techniques. PMID:12625885

Powell, Steven; Perry, John; Meikle, David

2003-02-01

320

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...

321

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...

322

Literature Review and Analysis of Coastal Urbanization and Microbial Contamination of Shellfish Growing Areas  

Microsoft Academic Search

Clean water is the key factor for determining the suitability of coastal areas for growing and harvesting shellfish. Clams, oysters and other filter-feeding shellfish can accumulate contaminants that may be present in the coastal environment. Shellfish growing areas are particularly vulnerable to fecal pollution from sewage systems, farm animal wastes, stormwater runoff, wildlife and other sources because of the health

Stuart Glasoe

323

Emerging contaminants in surface waters and their relevance for the production of drinking water in Europe  

Microsoft Academic Search

An increasing part of drinking water in Europe is prepared from surface water. At the same time, a growing number of emerging contaminants is being discovered in surface water. This review provides an overview of classes of emerging contaminants nowadays detected in the aquatic environment that are of relevance for drinking water production. These comprise e.g. endocrine disrupting compounds, such

Corine J. Houtman

2010-01-01

324

Application of gamma irradiation to reduce microbial contamination in herbal cosmetic products  

NASA Astrophysics Data System (ADS)

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.

Neramitmansook, Naruemon; Chahorm, Kanchana; Prakhongsil, Panchalee; Phianphak, Wannipa; Keawchoung, Pravait

2012-08-01

325

Dissolved metal concentrations in surface waters from west-central Indiana contaminated with acidic mine drainage  

SciTech Connect

A significant amount of coal mining activity in the west-central region of Indiana, has resulted in a large number of sites where surface waters are contaminated with acidic mine drainage (AMD). Contamination of drinking and irrigation water supplies is of concern mainly due to elevated levels of toxic metals. Abandoned mine sites are frequently located near occupied houses and farms in rural areas. Consequently, constituents of surface waters contaminated by AMD have the potential to be transported into sub-surface drinking water wells and irrigation water supplies. The extent of surface water contamination in west-central Indiana by AMID is not well characterized. For this reason, samples of surface waters that are contaminated with AMD were collected from a wide variety of locations in west-central Indiana and subjected to metals analysis.

Allen, S.K.; Allen, J.M.; Lucas, S. [Indiana State Univ., Terre Haute, IN (United States)] [Indiana State Univ., Terre Haute, IN (United States)

1996-02-01

326

Formation of recent Pb-Ag-Au mineralization by potential sub-surface microbial activity  

NASA Astrophysics Data System (ADS)

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.

Tornos, Fernando; Velasco, Francisco; Menor-Salván, César; Delgado, Antonio; Slack, John F.; Escobar, Juan Manuel

2014-08-01

327

Formation of recent Pb-Ag-Au mineralization by potential sub-surface microbial activity.  

PubMed

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 ?(13)C 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 × 10(9)?moles of reduced sulphur and 10(10)?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. PMID:25098677

Tornos, Fernando; Velasco, Francisco; Menor-Salván, César; Delgado, Antonio; Slack, John F; Escobar, Juan Manuel

2014-01-01

328

Surface and borehole electromagnetic imaging of conducting contaminant plumes  

SciTech Connect

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.

Berryman, J. G., LLNL

1998-07-01

329

Materials SIG quantification and characterization of surface contaminants  

NASA Technical Reports Server (NTRS)

When LDEF entered orbit its cleanliness was approximately a MIL-STD-1246B Level 2000C. Its burden of contaminants included particles from every part of its history including a relatively small contribution from the shuttle bay itself. Although this satellite was far from what is normally considered clean in the aerospace industry, contaminating events in orbit and from processing after recovery were easily detected. The molecular contaminants carried into orbit were dwarfed by the heavy deposition of UV polymerized films from outgassing urethane paints and silicone based materials. Impacts by relatively small objects in orbit could create particulate contaminants that easily dominated the particle counts within a centimeter of the impact site. During the recovery activities LDEF was 'sprayed' with a liquid high in organics and water soluble salts. With reentry turbulence, vibration, and gravitational loading particulate contaminants were redistributed about LDEF and the shuttle bay.

Crutcher, E. Russ

1992-01-01

330

The Effect of Surface Contamination on Adhesive Forces as Measured by Contact Mechanics  

SciTech Connect

The contact adhesive forces between two surfaces, one being a soft hemisphere and the other being a hard plate, can readily be determined by applying an external compressive load to mate the two surfaces and subsequently applying a tensile load to peel the surfaces apart. The contact region is assumed the superposition of elastic Hertzian pressure and of the attractive surface forces that act only over the contact area. What are the effects of the degree of surface contamination on adhesive forces? Clean aluminum surfaces were coated with hexadecane as a controlled contaminant. The force required to pull an elastomeric hemisphere from a surface was determined by contact mechanics, via the JKR model, using a model siloxane network for the elastomeric contact sphere. Due to the dispersive nature of the elastomer surface, larger forces were required to pull the sphere from a contaminated surface than a clean aluminum oxide surface.

EMERSON,JOHN A.; GIUNTA,RACHEL K.; MILLER,GREGORY V.; SORENSEN,CHRISTOPHER R.; PEARSON,RAYMOND A.

2000-12-18

331

A Method for Selectively Enriching Microbial DNA from Contaminating Vertebrate Host DNA  

PubMed Central

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

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

332

A method for selectively enriching microbial DNA from contaminating vertebrate host DNA.  

PubMed

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

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

333

Microbial contamination of manually reprocessed, ready to use ECG lead wire in intensive care units  

PubMed Central

Background: A number of studies have shown that non-critical medical devices can be contaminated with pathogens, including those resistant to antibiotics and thus become a potential vector for transmission. Electrocardiography (ECG) lead wire are non-critical medical device which are always attached on patient skin during their stay in intensive care unit (ICU). In view of the patient’s critical conditions and exposure to invasive procedures, identification and prevention of possible risks are important to prevent infection in ICUs. Objective: The objective of this study was to determine the presence of bacterial and fungal contamination on cleaned and disinfected reusable ECG lead wires in intensive care units in a hospital. Methods: A total of 408 cleaned ECG lead wires from 93 bed-side ECG devices and 43 ECG lead wires from 5 portable ECG devices from 4 intensive care units (ICUs) and 1 post-anaesthesia care unit (PACU) were sampled. ECG lead wires were stirred in 0.89% NaCl with added neutralizer for 30 seconds. Samples of the solutions were cultured directly on blood agar. The remaining solution was cultured on blood agar after sterile filtration. The number of colony forming units (CFUs) was counted and the microorganisms were identified. Results: More than half of examined ECG lead wires (n=232; 51.4%) were contaminated with >30 CFUs/mL sample of bacteria or with risk pathogens. Gram-positive bacteria were the most frequently isolated organisms; particularly, coagulase negative staphylococci (96%) and aerobic spore forming bacteria (71.2%). Compared to ICUs, PACU had significantly lower proportion of contaminated ECG lead wires (p<0.05). The proportion of contaminated ECG lead wires, as well as mean number of cfus per ECG lead wire, was also significantly lower among multi-wire ECG leads compared to single-wire ECG leads. Conclusions: Manually cleaned ECG lead wires may serve as a vector for transmission of nosocomial pathogens. The current reprocessing technique for ECG lead wires needs to be improved. PMID:23967393

Lestari, Trisasi; Ryll, Sylvia; Kramer, Axel

2013-01-01

334

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

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.

Bender, J.; Phillips, P.

1996-09-24

335

Effect of Microscale Surface Geometry of Electrodes on Performance of Microbial Fuel Cells  

NASA Astrophysics Data System (ADS)

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.

Kano, Tomonori; Suito, Eiichi; Hishida, Koichi; Miki, Norihisa

2012-06-01

336

UV detector monitors organic contamination of optical surfaces  

NASA Technical Reports Server (NTRS)

Silicon carbide, insensitive to visible light, is used in photodetectors. System contamination can be monitored during the normal operation without interference to the operator, and without shielding from ambient light.

Glenn, C. G.; Kennedy, B. W.

1968-01-01

337

Bacterial and archaeal communities in long-term contaminated surface and subsurface soil evaluated through coextracted RNA and DNA.  

PubMed

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

Mikkonen, Anu; Santalahti, Minna; Lappi, Kaisa; Pulkkinen, Anni-Mari; Montonen, Leone; Suominen, Leena

2014-10-01

338

Microbial biodiversity in cheese consortia and comparative Listeria growth on surfaces of uncooked pressed cheeses.  

PubMed

The study set out to determine how changes in the microbial diversity of a complex antilisterial consortium from the surface of St-Nectaire cheese modify its antilisterial activities. On the basis of the microbial composition of a natural complex consortium named TR15 (Truefood consortium 15), three new consortia of different species and strain compositions were defined: TR15-SC (58 isolates from TR15 collection), TR15-M (pools of isolates from selective counting media) and TR15-BHI (pools of isolates from BHI medium). Their antilisterial activities on the surfaces of uncooked pressed cheese made with pasteurised milk were compared with the activity of complex consortium TR15 and a control cheese inoculated only with starter culture (Streptococcus thermophilus, Lactobacillus delbrueckii). The natural consortium TR15 was the most inhibitory, followed by reconstituted consortium TR15-BHI. The dynamics of the cheese rind microbial flora were monitored by counting on media and by isolate identification using 16S rDNA sequencing and direct 16S rDNA Single Strand Conformation Polymorphism analysis. The combination of these methods showed that rind with natural consortium TR15 had greater microbial diversity and different microbial dynamics than cheese rinds with reconstituted consortia. Cheese rind with the natural consortium showed higher citrate consumption and the highest concentrations of lactic and acetic acids, connected with high levels of lactic acid bacteria such as Carnobacterium maltaromaticum, Vagococcus fluvialis, Enterococcus gilvus, Leuconostoc mesenteroides, Brochothrix thermosphacta and Lactococcus lactis, ripening bacteria such as Arthrobacter nicotianae/arilaitensis, and Gram negative bacteria (Pseudomonas psychrophila and Enterobacter spp.). The highest L. monocytogenes count was on rind with TR15-M and was positively associated with the highest pH value, high succinic and citric acid contents, and the highest levels of Marinilactibacillus psychrotolerans and Gram positive catalase positive bacteria represented by Staphylococcus vitulinus, Brevibacterium linens, Microbacterium gubbeenense and Brachybacterium tyrofermentans. The results show that the species composition of consortium is more important than the number of species. It is likely that inhibition mechanisms differ from one consortium to another; investigating gene expression will be an effective way to elucidate microbial interactions in cheese. PMID:24463156

Callon, Cécile; Retureau, Emilie; Didienne, Robert; Montel, Marie-Christine

2014-03-17

339

Efficacy of neutral electrolyzed water (NEW) for reducing microbial contamination on minimally-processed vegetables.  

PubMed

Consumption of minimally-processed, or fresh-cut, fruit and vegetables has rapidly increased in recent years, but there have also been several reported outbreaks associated with the consumption of these products. Sodium hypochlorite is currently the most widespread disinfectant used by fresh-cut industries. Neutral electrolyzed water (NEW) is a novel disinfection system that could represent an alternative to sodium hypochlorite. The aim of the study was to determine whether NEW could replace sodium hypochlorite in the fresh-cut produce industry. The effects of NEW, applied in different concentrations, at different treatment temperatures and for different times, in the reduction of the foodborne pathogens Salmonella, Listeria monocytogenes and Escherichia coli O157:H7 and against the spoilage bacterium Erwinia carotovora were tested in lettuce. Lettuce was artificially inoculated by dipping it in a suspension of the studied pathogens at 10(8), 10(7) or 10(5) cfu ml(-1), depending on the assay. The NEW treatment was always compared with washing with deionized water and with a standard hypochlorite treatment. The effect of inoculum size was also studied. Finally, the effect of NEW on the indigenous microbiota of different packaged fresh-cut products was also determined. The bactericidal activity of diluted NEW (containing approximately 50 ppm of free chlorine, pH 8.60) against E. coli O157:H7, Salmonella, L. innocua and E. carotovora on lettuce was similar to that of chlorinated water (120 ppm of free chlorine) with reductions of 1-2 log units. There were generally no significant differences when treating lettuce with NEW for 1 and 3 min. Neither inoculation dose (10(7) or 10(5) cfu ml(-1)) influenced the bacterial reduction achieved. Treating fresh-cut lettuce, carrot, endive, corn salad and 'Four seasons' salad with NEW 1:5 (containing about 50 ppm of free chlorine) was equally effective as applying chlorinated water at 120 ppm. Microbial reduction depended on the vegetable tested: NEW and sodium hypochlorite treatments were more effective on carrot and endive than on iceberg lettuce, 'Four seasons' salad and corn salad. The reductions of indigenous microbiota were smaller than those obtained with the artificially inoculated bacteria tested (0.5-1.2 log reduction). NEW seems to be a promising disinfection method as it would allow to reduce the amount of free chlorine used for the disinfection of fresh-cut produce by the food industry, as the same microbial reduction as sodium hypochlorite is obtained. This would constitute a safer, 'in situ', and easier to handle way of ensuring food safety. PMID:18237810

Abadias, Maribel; Usall, Josep; Oliveira, Márcia; Alegre, Isabel; Viñas, Inmaculada

2008-03-31

340

Molecular Analysis of Surfactant-Driven Microbial Population Shifts in Hydrocarbon-Contaminated Soil†  

PubMed Central

We analyzed the impact of surfactant addition on hydrocarbon mineralization kinetics and the associated population shifts of hydrocarbon-degrading microorganisms in soil. A mixture of radiolabeled hexadecane and phenanthrene was added to batch soil vessels. Witconol SN70 (a nonionic, alcohol ethoxylate) was added in concentrations that bracketed the critical micelle concentration (CMC) in soil (CMC?) (determined to be 13 mg g?1). Addition of the surfactant at a concentration below the CMC? (2 mg g?1) did not affect the mineralization rates of either hydrocarbon. However, when surfactant was added at a concentration approaching the CMC? (10 mg g?1), hexadecane mineralization was delayed and phenanthrene mineralization was completely inhibited. Addition of surfactant at concentrations above the CMC? (40 mg g?1) completely inhibited mineralization of both phenanthrene and hexadecane. Denaturing gradient gel electrophoresis of 16S rRNA gene segments showed that hydrocarbon amendment stimulated Rhodococcus and Nocardia populations that were displaced by Pseudomonas and Alcaligenes populations at elevated surfactant levels. Parallel cultivation studies revealed that the Rhodococcus population can utilize hexadecane and that the Pseudomonas and Alcaligenes populations can utilize both Witconol SN70 and hexadecane for growth. The results suggest that surfactant applications necessary to achieve the CMC alter the microbial populations responsible for hydrocarbon mineralization. PMID:10877792

Colores, Gregory M.; Macur, Richard E.; Ward, David M.; Inskeep, William P.

2000-01-01

341

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

PubMed

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 different RTE products are needed to ensure RTE food safety. The objectives of this study were to investigate and to model the surface cross-contamination of E. coli O157:H7 during slicing operation. A five-strain cocktail of E. coli O157:H7 was inoculated directly onto a slicer's round blade rim area at an initial level of ca. 4, 5, 6, 7 or 8 log CFU/blade (ca. 3, 4, 5, 6 or 7 log CFU/cm(2) of the blade edge area), and then the RTE deli meat (ham) was sliced to a thickness of 1-2 mm. For another cross-contamination scenario, a clean blade was initially used to slice ham which was pre-surface-inoculated with E. coli O157:H7 (ca. 4, 5, 6, 7 or 8 log CFU/100 cm(2) area), then, followed by slicing un-inoculated ham. Results showed that the developed empirical models were reasonably accurate in describing the transfer trend/pattern of E. coli O157:H7 between the blade and ham slices when the total inoculum level was >or=5 log CFU on the ham or blade. With an initial inoculum level at microbial surface transfer pattern. The models, i.e., a power equation for direct-blade-surface-inoculation, and an exponential equation for ham-surface-inoculation are microbial load and sequential slice index dependent. The surface cross-contamination prediction of E. coli O157:H7 for sliced deli meat (ham) using the developed models were demonstrated. The empirical models may provide a useful tool in developing the RTE meat risk assessment. PMID:19913690

Sheen, Shiowshuh; Hwang, Cheng-An

2010-02-01

342

Evaluation of Two Library-Independent Microbial Source Tracking Methods To Identify Sources of Fecal Contamination in French Estuaries?  

PubMed Central

In order to identify the origin of the fecal contamination observed in French estuaries, two library-independent microbial source tracking (MST) methods were selected: (i) Bacteroidales host-specific 16S rRNA gene markers and (ii) F-specific RNA bacteriophage genotyping. The specificity of the Bacteroidales markers was evaluated on human and animal (bovine, pig, sheep, and bird) feces. Two human-specific markers (HF183 and HF134), one ruminant-specific marker (CF193?), and one pig-specific marker (PF163) showed a high level of specificity (>90%). However, the data suggest that the proposed ruminant-specific CF128 marker would be better described as an animal marker, as it was observed in all bovine and sheep feces and 96% of pig feces. F RNA bacteriophages were detected in only 21% of individual fecal samples tested, in 60% of pig slurries, but in all sewage samples. Most detected F RNA bacteriophages were from genotypes II and III in sewage samples and from genotypes I and IV in bovine, pig, and bird feces and from pig slurries. Both MST methods were applied to 28 water samples collected from three watersheds at different times. Classification of water samples as subject to human, animal, or mixed fecal contamination was more frequent when using Bacteroidales markers (82.1% of water samples) than by bacteriophage genotyping (50%). The ability to classify a water sample increased with increasing Escherichia coli or enterococcus concentration. For the samples that could be classified by bacteriophage genotyping, 78% agreed with the classification obtained from Bacteroidales markers. PMID:17557850

Gourmelon, Michele; Caprais, Marie Paule; Segura, Raphael; Le Mennec, Cecile; Lozach, Solen; Piriou, Jean Yves; Rince, Alain

2007-01-01

343

Transport of E. coli in aquifer sediments of Bangladesh: Implications for widespread microbial contamination of groundwater  

NASA Astrophysics Data System (ADS)

Fecal bacteria are frequently found at much greater distances than would be predicted by laboratory studies, indicating that improved models that incorporate more complexity might be needed to explain the widespread contamination of many shallow aquifers. In this study, laboratory measurements of breakthrough and retained bacteria in columns of intact and repacked sediment cores from Bangladesh were fit using a two-population model with separate reversible and irreversible attachment sites that also incorporated bacterial decay rates. Separate microcosms indicated an average first-order decay rate of 0.03 log10/day for both free bacteria in the liquid phase and bacteria attached to the solid phase. Although two thirds of the column results could be well fit with a dual-deposition site, single-population model, fitting of one third of the results required a two-population model with a high irreversible attachment rate (between 5 and 60 h-1) for one population of bacteria and a much lower rate (from 5 h-1 to essentially zero) for the second. Inferred attachment rates for the reversible sites varied inversely with grain size (varying from 1 to 20 h-1 for grain sizes between 0.1 and 0.3 mm) while reversible detachment rates were found to be nearly constant (approximately 0.5 h-1). Field simulations based on the fitted two-population model parameters predict only a twofold reduction in fecal source concentration over a distance of 10 m, determined primarily by the decay rate of the bacteria. The existence of a secondary population of bacteria with a low attachment rate might help explain the observed widespread contamination of tubewell water with E. coli at the field site where the cores were collected as well as other similar sites.

Feighery, John; Mailloux, Brian J.; Ferguson, A. S.; Ahmed, Kazi Matin; Geen, Alexander; Culligan, Patricia J.

2013-07-01

344

Microbial Communities and Functional Genes Associated with Soil Arsenic Contamination and the Rhizosphere of the Arsenic-Hyperaccumulating Plant Pteris vittata L. ? †  

PubMed Central

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

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

2010-01-01

345

Plastic deformation to enhance plasma-assisted nitriding: On surface contamination induced by Surface Mechanical Attrition Treatment  

NASA Astrophysics Data System (ADS)

The Surface Mechanical Attrition Treatment is a recent technique leading to the formation of nanostructured layers by the repeated action of impacting balls. While several communications have revealed possible contamination of the SMATed surfaces, the nature of this surface contamination was analyzed in the present contribution for the treatment of an AISI 316L stainless steel. It is shown, by a combination of Transmission Electron Microscopy and Glow Discharge – Optical Emission Spectrometry, that the surface was alloyed with Ti, Al and V coming from the sonotrode that is used to move the balls as well as Zr coming from the zirshot® balls themselves.

Samih, Youssef; Novelli, Marc; Thiriet, Tony; Bolle, Bernard; Allain, Nathalie; Fundenberger, Jean-Jacques; Marcos, Grégory; Czerwiec, Thierry; Grosdidier, Thierry

2014-08-01

346

Effect of Different Disinfection Protocols on Microbial and Biofilm Contamination of Dental Unit Waterlines in Community Dental Practices  

PubMed Central

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

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

347

Novel atmospheric pressure plasma device releasing atomic hydrogen: reduction of microbial-contaminants and OH radicals in the air  

NASA Astrophysics Data System (ADS)

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.

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

348

Biodegradation Processes in a Laboratory-Scale Groundwater Contaminant Plume Assessed by Fluorescence Imaging and Microbial Analysis?  

PubMed Central

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

Rees, Helen C.; Oswald, Sascha E.; Banwart, Steven A.; Pickup, Roger W.; Lerner, David N.

2007-01-01

349

Laser-ion acceleration through controlled surface contamination  

SciTech Connect

In laser-plasma ion accelerators, control of target contamination layers can lead to selection of accelerated ion species and enhancement of acceleration. To demonstrate this, deuterons up to 75 keV are accelerated from an intense laser interaction with a glass target simply by placing 1 ml of heavy water inside the experimental chamber prior to pumping to generate a deuterated contamination layer on the target. Using the same technique with a deuterated-polystyrene-coated target also enhances deuteron yield by a factor of 3 to 5, while increasing the maximum energy of the generated deuterons to 140 keV.

Hou Bixue; Nees, John A.; He Zhaohan; Easter, James H.; Thomas, Alexander G. R.; Krushelnick, Karl M. [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Blvd., Ann Arbor, Michigan 48109-2099 (United States); Petrov, George; Davis, Jack [Naval Research Laboratory, Plasma Physics Division, 4555 Overlook Ave. SW, Washington, DC 20375 (United States)

2011-04-15

350

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...

351

A Laboratory Evaluation of Wipe Testing Based on Lead Oxide Surface Contamination  

Microsoft Academic Search

Although wipe testing has been used extensively as a measure of surface contamination in industrial hygiene, few scientific studies have been reported to validate the procedure with respect to quantitative recovery, repeatability or methodology. Consequently, a laboratory evaluation of wipe testing with particular attention to the OSHA procedure was undertaken using lead oxide dust as the test contaminant. A dust

CHAIYUTH CHAVALITNITIKUL; LESTER LEVIN

1984-01-01

352

Modelling homogeneous and heterogeneous microbial contaminations in a powdered food product.  

PubMed

The actual physical distribution of microorganisms within a batch of food influences quantification of microorganisms in the batch, resulting from sampling and enumeration by microbiological tests. Quantification may be most accurate for batches in which microorganisms are distributed homogeneously. However, when the distribution is non-homogeneous, quantification may result in an under-, or overestimation. In the case of pathogens being non-homogeneously distributed, this heterogeneity will impact on public health. Enumeration data are commonly modelled by the Lognormal distribution. Although the Lognormal distribution can model heterogeneity, it does not allow for complete absence of microorganisms. Studies that validate the appropriateness of using Lognormal or other statistical distributions are scarce. This study systematically investigated laboratory and industrial scale batches of powdered infant formula, modelled the enumeration data using a range of statistical distributions, and assessed the appropriateness of individual models. For laboratory scale experiments, batches of milk powder were contaminated by distributing similar numbers of cells of Cronobacter sakazakii either homogeneously throughout a batch of milk powder or by distributing the cells in a localised part of the batch. Each batch was then systematically sampled and the distribution determined by enumerating the samples. By also enumerating the remainder of the batch, a balance could be made of the total number of microorganisms added and of the number retrieved from a batch. Discrete, as well as continuous statistical distributions, were fitted to enumeration data and the parameters estimated by Maximum Likelihood. The data were fitted both as censored and uncensored data. Enumeration data obtained for an industrial batch of powdered infant formula were investigated in this way as well. It was found that Normal, Poisson and Zero-Inflated Poisson distributions fitted the data sets very poorly. In case of homogeneous contamination, there was not a notable difference between the ability of Negative Binomial, Poisson-Lognormal, Weibull, Gamma, and Lognormal distributions to model the data. Overall, either the Negative Binomial distribution or the Poisson-Lognormal distribution fitted the data best in the 10 batches studied, especially when part of a data set contained zeros and/or the numbers were low. The Negative Binomial fitted the laboratory batches best and the Poisson-Lognormal fitted the industrial batch best. PMID:22591548

Jongenburger, I; Reij, M W; Boer, E P J; Zwietering, M H; Gorris, L G M

2012-06-15

353

Microbially driven fracture sealing for inhibiting contaminant transport at the field scale  

NASA Astrophysics Data System (ADS)

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.

McMillan, Lindsay; Cuthbert, Mark; Riley, Michael; Handley-Sidhu, Stephanie; Tobler, Dominique; Phoenix, Vernon

2013-04-01

354

Comparison of Two Mercury Contaminated Surface Water Bodies  

Microsoft Academic Search

Due to the methyl mercury (MeHg) burden in fish tissues, the Virginia Department of Health and the Tennessee Department of Environment and Conservation have posted fish advisories for the South River, VA and the East Fork Poplar Creek, TN (EFPC), respectively. This presentation will compare and contrast the hydrogeochemical characteristics of these two industrially contaminated water bodies. Both streams share

S. C. Brooks; G. R. Southworth; R. R. Turner; R. Jensen

2008-01-01

355

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 ...

356

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 ...

357

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...

358

Microbial biosafety of pilot-scale bioreactor treating MTBE and TBA-contaminated drinking water supply  

PubMed Central

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

Schmidt, Radomir; Klemme, David A.; Scow, Kate; Hristova, Krassimira

2012-01-01

359

Microbial contamination in vegetables due to irrigation with partially treated municipal wastewater in a tropical city.  

PubMed

A total of 144 samples of water used for irrigation were collected from Dinapur, DLW sewage treatment plant and river water of Ganga at Rajghat and 258 irrigated vegetable samples were collected from nearby agricultural fields in the close vicinity of three treatment plants and examined using standard procedures for coliform and viable counts and the presence of Escherichia coli, Salmonella, Clostridium and Vibrio during the winter and rainy seasons. Irrigation water from Rajghat drain had significantly higher coliform counts by location and season than the water from the Dinapur and DLW. Although all the vegetables had coliform counts higher than the recommended standard (range 3.40 - 6.38 log10 cfuml(-1)), spinach and cabbage had significantly higher (p < 0.05) counts compared to other vegetables during the dry season. Salmonella was significantly more likely to be detected during the rainy season than during the dry season. Contaminated vegetable intake may pose a serious threat to human health. PMID:17924267

Rai, Prabhat Kumar; Tripathi, B D

2007-10-01

360

Power enhancement of a ?l-scale microbial fuel cells by surface roughness  

NASA Astrophysics Data System (ADS)

In recent years, microbial fuel cells (MFCs) have gained much attention due to their potential to generate energy in a sustainable manner from living microorganisms. Research has shown that electrode design is a critical factor for MFCs power enhancement. In this study, we designed and fabricated MFCs energy-harvesting devices with living bacteria, and we investigated the effect of the surface roughness of the electrodes on power generation. In batch experiments of our MFCs, we found that the total power delivered could be enhanced using electrodes having rough surfaces with protruded micro-structures relative to that of electrodes with a flat surface. This was due to the delayed acidification resulting from the changes in bio-film formation between them.

Kim, Jihoon; Hwan Ko, Jin; Lee, Jaehyun; Jun Kim, Min; Byun, Doyoung

2014-06-01

361

Filtering the surface EMG signal: Movement artifact and baseline noise contamination  

E-print Network

Filtering the surface EMG signal: Movement artifact and baseline noise contamination Carlo J. De a b s t r a c t The surface electromyographic (sEMG) signal that originates in the muscle reserved. 1. Introduction The surface electromyographic (sEMG) signal contains the signal that originates

De Luca, Carlo J.

362

Removal of contaminated concrete surfaces by microwave heating: Phase 1 results  

Microsoft Academic Search

Oak Ridge National Laboratory (ORNL) is developing a microwave heating process to remove radiologically contaminated surface layers from concrete. The microwave energy is directed at the concrete surface and heats the concrete and free water present in the concrete matrix. Continued heating produces steam-pressure-induced mechanical stresses that cause the concrete surface to burst. The concrete particles from this steam explosion

T. L. White; R. G. Grubb; L. P. Pugh; D. Jr. Foster; W. D. Box

1992-01-01

363

Active cleaning techniques for removing contamination from optical surfaces in space  

NASA Technical Reports Server (NTRS)

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.

Shannon, R. L.; Gillette, R. B.

1973-01-01

364

Long-Term Recovery of PCB-Contaminated Surface Sediments at the Sangamo-Weston \\/ Twelvemile Creek \\/ Lake Hartwell Superfund Site  

Microsoft Academic Search

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 contaminant transport into the food chain by limiting bioturbation of contaminated surface or near-surface sediments. This study evaluated the natural recovery of surface

Richard C. Brenner; Victor S. Magar; Jennifer A. Ickes; Eric A. Foote; James E. Abbott; Linda S. Bingler; Eric A. Crecelius

2004-01-01

365

Persistence of Microbial Contamination on Transvaginal Ultrasound Probes despite Low-Level Disinfection Procedure  

PubMed Central

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

M'Zali, Fatima; Bounizra, Carole; Leroy, Sandrine; Mekki, Yahia; Quentin-Noury, Claudine; Kann, Michael

2014-01-01

366

TECHNICAL BASIS FOR EVALUATING SURFACE BARRIERS TO PROTECT GROUNDWATER FROM DEEP VADOSE ZONE CONTAMINATION  

SciTech Connect

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

FAYER JM; FREEDMAN VL; WARD AL; CHRONISTER GB

2010-02-24

367

Active cleaning technique for removing contamination from optical surfaces in space  

NASA Technical Reports Server (NTRS)

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.

Shannon, R. L.; Gillette, R. B.; Cruz, G. A.

1973-01-01

368

Final Report: Molecular Basis for Microbial Adhesion and Geochemical Surface Reactions: A Study Across Scales  

SciTech Connect

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.

Dixon, David Adams [The University of Alabama

2013-06-27

369

Mineralogical controls on surface colonization by sulfur-metabolizing microbial communities  

NASA Astrophysics Data System (ADS)

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.

Jones, A. A.; Bennett, P.

2012-12-01

370

Chemical analysis of outgassing contaminants on spacecraft surfaces  

NASA Technical Reports Server (NTRS)

Methods for analyzing and characterizing outgassing contaminants from such materials as RTV 501 potting compound and S 13 G paint are presented. Fractional distillation of a gross distillate from RTV 501 rubber was carried out and the distilled fractions examined as to their ultraviolet and infrared spectra by gas liquid chromatography. A sensitive technique for structural analysis and molecular identification was found to consist of a gas chromatography-mass spectroscopy system, which was determined to be economically unfeasible at present.

Mcnutt, R. C.

1973-01-01

371

Combined Contamination and Space Environmental Effects on Solar Cells and Thermal Control Surfaces  

NASA Technical Reports Server (NTRS)

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.

Dever, Joyce A.; Bruckner, Eric J.; Scheiman, David A.; Stidham, Curtis R.

1994-01-01

372

Microbial Diversity Aboard Spacecraft: Evaluation of the International Space Station  

NASA Technical Reports Server (NTRS)

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.

Castro, Victoria A.; Thrasher, Adrianna N.; Healy, Mimi; Ott, C. Mark; Pierson, Duane L.

2003-01-01

373

Microbial diversity, community composition and metabolic potential in hydrocarbon contaminated oily sludge: prospects for in situ bioremediation.  

PubMed

Microbial community composition and metabolic potential have been explored in petroleum-hydrocarbon-contaminated sludge of an oil storage facility. Culture-independent clone library-based 16S rRNA gene analyses revealed that the bacterial community within the sludge was dominated by the members of ?-Proteobacteria (35%), followed by Firmicutes (13%), ?-Proteobacteria (11%), Bacteroidetes (10%), Acidobacteria (6%), ?-Proteobacteria (3%), Lentisphaerae (2%), Spirochaetes (2%), and unclassified bacteria (5%), whereas the archaeal community was composed of Thermoprotei (54%), Methanocellales (33%), Methanosarcinales/Methanosaeta (8%) and Methanoculleus (1%) members. Methyl coenzyme M reductase A (mcrA) gene (a functional biomarker) analyses also revealed predominance of hydrogenotrophic, methanogenic Archaea (Methanocellales, Methanobacteriales and Methanoculleus members) over acetoclastic methanogens (Methanosarcinales members). In order to explore the cultivable bacterial population, a total of 28 resident strains were identified and characterized in terms of their physiological and metabolic capabilities. Most of these could be taxonomically affiliated to the members of the genera Bacillus, Paenibacillus, Micrococcus, Brachybacterium, Aerococcus, and Zimmermannella, while two strains were identified as Pseudomonas and Pseudoxanthomonas. Metabolic profiling exhibited that majority of these isolates were capable of growing in presence of a variety of petroleum hydrocarbons as sole source of carbon, tolerating different heavy metals at higher concentrations (?1 mM) and producing biosurfactant during growth. Many strains could grow under a wide range of pH, temperature, or salinity as well as under anaerobic conditions in the presence of different electron acceptors and donors in the growth medium. Correlation between the isolates and their metabolic properties was estimated by the unweighted pair group method with arithmetic mean (UPGMA) analysis. Overall observation indicated the presence of diverse groups of microorganisms including hydrocarbonoclastic, nitrate reducing, sulphate reducing, fermentative, syntrophic, methanogenic and methane-oxidizing bacteria and Archaea within the sludge community, which can be exploited for in situ bioremediation of the oily sludge. PMID:24682711

Das, Ranjit; Kazy, Sufia K

2014-06-01

374

Prevention: A New and Maybe Wiser Approach to the Surface Contamination Issues  

SciTech Connect

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.

Rouppert, F.; Santarella, I.; Ackermann, E.; Tiquet, P.; Secourgeon, L.

2003-02-26

375

Was Mineral Surface Complexity and Toxicity an Impetus for Evolution of Microbial Extracellular Polymeric Substances?  

NASA Astrophysics Data System (ADS)

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.

Sahai, N.; Xu, J.; Zhu, C.; Campbell, J.; Hickey, W.; Zhang, N.

2011-12-01

376

Depth profiling of polishing-induced contamination on fused silica surfaces  

SciTech Connect

Laser-induced damage on optical surfaces is often associated with absorbing contaminants introduced by the polishing process. This is particularly the case for UV optics. Here secondary ion mass spectroscopy (SIMS) was used to measure depth profiles of finished process contamination on fused silica surfaces. Contaminants detected include the major polishing compound components (Ce or Zr from CeO2 or ZrO2), Al presently largely because of the use of Al2O3 in the final cleaning process (Fe, Cu,Cr) incorporated during the polishing step or earlier grinding steps. Depth profile data typically showed an exponential decay of contaminant concentration to a depth of 100-200 nm. This depth is consistent with a polishing redeposition layers formed during the chemo-mechanical polishing of fused silica. Peak contaminant levels are typically in the 10-100 ppm range, except for Al with exceeds 1000 ppm. A strong correlation has been shown between the presence of a gray haze damage morphology and the use of CeO2 polishing compound. No strong correlation was found however between high levels of Ce, or any other contaminant and the low damage threshold was observed. In fact one of the strongest indications of a correlation is between increased damage thresholds and increased Zr contamination. This suggests that the correlation between redeposition layer and laser damage threshold is not simple an absorbing contaminant issue.

Kozlowski, M.R.; Carr, J.; Hutcheon, I,; Torres, R.; Sheehan, L. Camp, D.; Yan, M.

1997-12-20

377

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...

378

Selection of an effective biocide and toxicity evaluation for a specific MEOR (microbial enhanced oil recovery) microbial formulation  

Microsoft Academic Search

The two major environmental impacts associated with microbial enhanced oil recovery (MEOR) are possible contamination of surface and groundwater and contamination of agricultural land. Other potential environmental problems associated with MEOR processes include changes in indigenous microflora in reservoirs caused by injection of nonindigenous microorganisms and nutrient, or the possibility of injected microorganisms mutating and producing undesirable compounds under reservoir

K. L. Chase; R. S. Bryant; K. M. Bertus; A. K. Stepp

1989-01-01

379

QMRAspot: a tool for Quantitative Microbial Risk Assessment from surface water to potable water.  

PubMed

In the Netherlands, a health based target for microbially safe drinking water is set at less than one infection per 10,000 persons per year. For the assessment of the microbial safety of drinking water, Dutch drinking water suppliers must conduct a Quantitative Microbial Risk Assessment (QMRA) at least every three years for the so-called index pathogens enterovirus, Campylobacter, Cryptosporidium and Giardia. In order to collect raw data in the proper format and to automate the process of QMRA, an interactive user-friendly computational tool, QMRAspot, was developed to analyze and conduct QMRA for drinking water produced from surface water. This paper gives a description of the raw data requirements for QMRA as well as a functional description of the tool. No extensive prior knowledge about QMRA modeling is required by the user, because QMRAspot provides guidance to the user on the quantity, type and format of raw data and performs a complete analysis of the raw data to yield a risk outcome for drinking water consumption that can be compared with other production locations, a legislative standard or an acceptable health based target. The uniform approach promotes proper collection and usage of raw data and, warrants quality of the risk assessment as well as enhances efficiency, i.e., less time is required. QMRAspot may facilitate QMRA for drinking water suppliers worldwide. The tool aids policy makers and other involved parties in formulating mitigation strategies, and prioritization and evaluation of effective preventive measures as integral part of water safety plans. PMID:21885080

Schijven, Jack F; Teunis, Peter F M; Rutjes, Saskia A; Bouwknegt, Martijn; de Roda Husman, Ana Maria

2011-11-01

380

Technical Basis for Evaluating Surface Barriers to Protect Groundwater from Deep Vadose Zone Contamination  

SciTech Connect

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.

Fayer, Michael J.; Ward, Anderson L.; Freedman, Vicky L.

2010-02-03

381

Exploring the optimum conditions for maximizing the microbial growth of Candida intermedia by response surface methodology.  

PubMed

Exploring optimum and cost-efficient medium composition for microbial growth of Candida intermedia Y-1981 yeast culture growing on whey was studied by applying a multistep response surface methodology. In the first step, Plackett-Burman (PB) design was utilized to determine the most significant fermentation medium factors on microbial growth. The medium temperature, sodium chloride and lactose concentrations were determined as the most important factors. Subsequently, the optimum combinations of the selected factors were explored by steepest ascent (SA) and central composite design (CCD). The optimum values for lactose and sodium chloride concentrations and medium temperature were found to be 18.4 g/L, 0.161 g/L, and 32.4°C, respectively. Experiments carried out at the optimum conditions revealed a maximum specific growth rate of 0.090 1/hr; 42% of total lactose removal was achieved in 24 h of fermentation time. The obtained results were finally verified with batch reactor experiments carried out under the optimum conditions evaluated. PMID:24117150

Yönten, Vahap; Akta?, Nahit

2014-01-01

382

Modeling of Transmittance Degradation Caused by Optical Surface Contamination by Atomic Oxygen Reaction with Adsorbed Silicones  

NASA Technical Reports Server (NTRS)

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 description of the procedure used to calculate the constituents of the contaminant layer is presented, including the equations that govern the evolution of fractional coverage by specie type. As an illustrative example of film growth, calculation results using a prototype code that calculates the evolution of surface coverage by specie type is presented and discussed. An example of the transmittance degradation caused by surface interaction of AO with deposited contaminant is presented for the case of exponentially decaying contaminant flux. These examples are performed using hypothetical values for the process parameters.

Snyder, Aaron; Banks, Bruce; Miller, Sharon; Stueber, Thomas; Sechkar, Edward

2001-01-01

383

Adhesion-creepage characteristics of wheel\\/rail system under dry and contaminated rail surfaces  

Microsoft Academic Search

This thesis presents an experimental and theoretical study of adhesion and creepage characteristics of wheel and rail under both dry and contaminated rail surfaces. The experimental work was conducted largely on the IIT 1\\/4.5 Scale Wheel\\/Rail Simulation Facility. Based on the experimental data in the laboratory, a theoretical model of adhesion and creepage relationship with different degrees of contamination was

Mohammed F. Alzoubi

1998-01-01

384

A Monte Carlo study of reflection electron energy loss spectroscopy spectrum of a carbon contaminated surface  

NASA Astrophysics Data System (ADS)

It has been experimentally found that the carbon surface contamination influences strongly the spectrum signals in reflection electron energy loss spectroscopy (REELS) especially at low primary electron energy. However, there is still little theoretical work dealing with the carbon contamination effect in REELS. Such a work is required to predict REELS spectrum for layered structural sample, providing an understanding of the experimental phenomena observed. In this study, we present a numerical calculation result on the spatially varying differential inelastic mean free path for a sample made of a carbon contamination layer of varied thickness on a SrTiO3 substrate. A Monte Carlo simulation model for electron interaction with a layered structural sample is built by combining this inelastic scattering cross-section with the Mott's cross-section for electron elastic scattering. The simulation results have clearly shown that the contribution of the electron energy loss from carbon surface contamination increases with decreasing primary energy due to increased individual scattering processes along trajectory parts carbon contamination layer. Comparison of the simulated spectra for different thicknesses of the carbon contamination layer and for different primary electron energies with experimental spectra clearly identifies that the carbon contamination in the measured sample was in the form of discontinuous islands other than the uniform film.

Da, B.; Li, Z. Y.; Chang, H. C.; Mao, S. F.; Ding, Z. J.

2014-09-01

385

Molecular Profiling of Microbial Communities from Contaminated Sources: Use of Subtractive Cloning Methods and rDNA Spacer Sequences  

SciTech Connect

The major objective of this research was to provide appropriate sequences and assemble a DNA array of oligonucleotides to be used for rapid profiling of microbial populations from polluted areas and other areas of interest. The sequences to be assigned to the DNA array were chosen from cloned genomic DNA taken from groundwater sites having well characterized pollutant histories at Hanford Nuclear Plant and Lawrence Livermore Site 300. Glass-slide arrays were made and tested; and a new multiplexed, bead-based method was developed that uses nucleic acid hybridization on the surface of microscopic polystyrene spheres to identify specific sequences in heterog