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1

Use of Ultrasonic Energy in Assessing Microbial Contamination on Surfaces  

PubMed Central

Ultrasonic tanks were evaluated for their ability to remove viable microorganisms from various surfaces for subsequent enumeration. Test surfaces were polished stainless steel, smooth glass, frosted glass, and electronic components. The position of contaminated surfaces in relation to the ultrasonic energy source, distance of the ultrasonic source from the test surfaces, and temperature of the rinse fluid were some of the factors which influenced recovery. Experimental systems included both naturally occurring microbial contamination and artificial contamination with spores of Bacillus subtilis var. niger. The results showed that ultrasonic energy was more reliable and efficient than mechanical agitation for recovering surface contaminants. Conditions which increased the number and percentage of microorganisms recovered by ultrasonic energy were: using a cold rinse fluid, placing the sample bottle on the bottom of the ultrasonic tank, and facing the contaminated surfaces toward the energy source. It was also demonstrated that ultrasonic energy could be effectively used for eluting microorganisms from cotton swabs.

Puleo, John R.; Favero, Martin S.; Petersen, Norman J.

1967-01-01

2

The index of microbial air contamination  

Microsoft Academic Search

The standard index of microbial air contamination (IMA) for the measurement of microbial air contamination in environments at risk is described. The method quantifies the microbial flow directly related to the contamination of surfaces coming from microbes that reach critical points by falling on to them. The index of microbial air contamination is based on the count of the microbial

C. Pasquarella; O. Pitzurra; A. Savino

2000-01-01

3

Surface charge based rapid method for detection of microbial contamination in drinking water and food products  

Microsoft Academic Search

Microbial contamination, most of which are fecal born in drinking water and food industry is a serious threat to humans. Escherichia coli is one of the most common and prevalent among them. We have developed a sensor for rapid and an early detection of contaminants, taking E.coli as a threat indicator organism. The sensor is based on co-polymerizations of aniline

Debnath M

2009-01-01

4

Diffuse PAH contamination of surface soils: environmental occurrence, bioavailability, and microbial degradation  

Microsoft Academic Search

The purpose of this review is to recognize the scientific and environmental importance of diffuse pollution with polycyclic\\u000a aromatic hydrocarbons (PAHs). Diffuse PAH pollution of surface soil is characterized by large area extents, low PAH concentrations,\\u000a and the lack of point sources. Urban and pristine topsoils receive a continuous input of pyrogenic PAHs, which induces a microbial\\u000a potential for PAH

Anders R. Johnsen; Ulrich Karlson

2007-01-01

5

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

EPA Science Inventory

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

6

Use of Negative Air Ionization for Reducing Microbial Contamination on Stainless Steel Surfaces  

Microsoft Academic Search

SUMMARY Microbiological concerns in food plant sanitation that relies heavily on physical and chemical methods for removing and killing bacteria could be reduced by the use of non-chemical intervention methods. This initial work on the effects of electrostatic space charge on biofilms shows promise as a viable intervention option for reducing bacterial contamination on surfaces. Natural bacterial populations from a

J. W. Arnold; B. W. Mitchell

2002-01-01

7

Microbial Contamination of Toothbrushes.  

National Technical Information Service (NTIS)

The degree of bacterial contamination of toothbrushes after contamination and storage in vented containers or in air was studied. The capacity of toothbrush containers to exclude microorganisms of the environment from the toothbrush was also investigated....

M. B. Dayoub D. Rusilko A. Gross

1976-01-01

8

Microbial populations in contaminant plumes  

USGS Publications Warehouse

Efficient biodegradation of subsurface contaminants requires two elements: (1) microbial populations with the necessary degradative capabilities, and (2) favorable subsurface geochemical and hydrological conditions. Practical constraints on experimental design and interpretation in both the hydrogeological and microbiological sciences have resulted in limited knowledge of the interaction between hydrogeological and microbiological features of subsurface environments. These practical constraints include: (1) inconsistencies between the scales of investigation in the hydrogeological and microbiological sciences, and (2) practical limitations on the ability to accurately define microbial populations in environmental samples. However, advances in application of small-scale sampling methods and interdisciplinary approaches to site investigations are beginning to significantly improve understanding of hydrogeological and microbiological interactions. Likewise, culture-based and molecular analyses of microbial populations in subsurface contaminant plumes have revealed significant adaptation of microbial populations to plume environmental conditions. Results of recent studies suggest that variability in subsurface geochemical and hydrological conditions significantly influences subsurface microbial-community structure. Combined investigations of site conditions and microbial-community structure provide the knowledge needed to understand interactions between subsurface microbial populations, plume geochemistry, and contaminant biodegradation.

Haack, S. K.; Bekins, B. A.

2000-01-01

9

Efficacy of home washing methods in controlling surface microbial contamination on fresh produce.  

PubMed

Much effort has been focused on sanitation of fresh produce at the commercial level; however, few options are available to the consumer. The purpose of this study was to determine the efficacy of different cleaning methods in reducing bacterial contamination on fresh produce in a home setting. Lettuce, broccoli, apples, and tomatoes were inoculated with Listeria innocua and then subjected to combinations of the following cleaning procedures: (i) soak for 2 min in tap water, Veggie Wash solution, 5% vinegar solution, or 13% lemon solution and (ii) rinse under running tap water, rinse and rub under running tap water, brush under running tap water, or wipe with wet/dry paper towel. Presoaking in water before rinsing significantly reduced bacteria in apples, tomatoes, and lettuce, but not in broccoli. Wiping apples and tomatoes with wet or dry paper towel showed lower bacterial reductions compared with soaking and rinsing procedures. Blossom ends of apples were more contaminated than the surface after soaking and rinsing; similar results were observed between flower section and stem of broccoli. Reductions of L. innocua in both tomatoes and apples (2.01 to 2.89 log CFU/g) were more than in lettuce and broccoli (1.41 to 1.88 log CFU/g) when subjected to same washing procedures. Reductions of surface contamination of lettuce after soaking in lemon or vinegar solutions were not significantly different (P > 0.05) from lettuce soaking in cold tap water. Therefore, educators and extension workers might consider it appropriate to instruct consumers to rub or brush fresh produce under cold running tap water before consumption. PMID:16496573

Kilonzo-Nthenge, Agnes; Chen, Fur-Chi; Godwin, Sandria L

2006-02-01

10

Distribution of microbial contamination within cereal grains  

Microsoft Academic Search

Some of the microorganisms present in cereals constitute a potential problem since their development may alter the properties of the grains, and the mycotoxins produced by some moulds could potentially pose a health risk. It has been reported that these microorganisms are located close to the surface of the grain, but the real thickness affected by microbial contamination has not

Adriana Laca; Zoe Mousia; Mario D??az; Colin Webb; Severino S. Pandiella

2006-01-01

11

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

12

Air-borne microbial contamination of surfaces in a UK dental clinic.  

PubMed

Little is known about the number, type, or antibiotic resistance profiles, of air-borne microbes present in hospital settings yet such information is important in designing effective measures to reduce cross-infection. In this study settle plates were used to identify and quantify the air-borne microbes present in a dental clinic. All isolates were identified to species level using partial 16S ribosomal RNA gene sequencing and their susceptibility to ampicillin, chloramphenicol, erythromycin, gentamicin, penicillin, tetracycline or vancomycin was performed. The mean numbers of viable bacteria detected for each sampling occasion during periods of clinical activity and in the absence of such activity were 21.9 x 10(2 )cfu/m2/h and 2.3 x 10(2 )cfu/m2/h respectively. One hundred ninety-three distinct colony morphotypes, comprising 73 species, were isolated during the study and 48% of these were resistant to at least one antibiotic. The mean numbers of different morphotypes detected per sampling occasion were 14.3 and 5 during periods of clinical activity and inactivity respectively. Propionibacterium acnes, Micrococcus luteus and Staphylococcus epidermidis were frequently isolated regardless of whether any clinical activities were taking place. These findings highlight the importance of preventing surfaces from becoming reservoirs of antibiotic-resistant bacteria and thereby contributing to cross-infection in the dental clinic. PMID:18802318

Decraene, Valérie; Ready, Derren; Pratten, Jonathan; Wilson, Michael

2008-08-01

13

Microbial populations in contaminant plumes  

NASA Astrophysics Data System (ADS)

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

Haack, Sheridan K.; Bekins, Barbara A.

14

Rhizosphere microbial populations in contaminated soils  

Microsoft Academic Search

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

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

1997-01-01

15

Effect of bioaugmentation on microbial transport, water infiltration, moisture loss, and surface hardness in pristine and contaminated soils.  

PubMed

Three different soils, a clay, a pristine sandy loam and a PCB-contaminated sandy loam, were bioaugmented to determine the influence of clay content and contaminants on the transport of bacteria in unsaturated soils, using surface irrigation water as a transport medium. The results indicate that the transport of the implanted bacteria was influenced negatively more by the presence of PCBs than by the clay content of the soil. Transport was directly related to the frequency of irrigation and length of the intervals between irrigation periods, making these variables important factors to consider when applying bioaugmentation via downward percolating water. Other parameters measured after bacterial bioaugmentation were water infiltration, moisture loss, and surface hardness of these soils. Surface water infiltration was affected more by the soil clay content than by the hydrophobic contaminant. Infiltration was significantly but differently influenced by bioaugmentation, positively in clay, negatively in sandy loam, and negatively (to a lesser extent) in the PCB-contaminated sandy loam soils. Moisture loss was slower in the bioaugmented soil than in the control soils, with this difference being most pronounced in the PCB soil. High moisture loss in the bioaugmented clay soil rendered it the hardest soil for surface penetration. PMID:11382015

Mehmannavaz, R; Prasher, S O; Ahmad, D

2001-01-01

16

Contaminant immobilization via microbial activity.  

National Technical Information Service (NTIS)

The aim of this study was to search the literature to identify biological techniques that could be applied to the restoration of contaminated groundwaters near uranium milling sites. Through bioremediation it was hypothesized that the hazardous heavy meta...

1991-01-01

17

Microbial contamination of musical wind instruments  

Microsoft Academic Search

Retrospective and prospective studies were used to assess the numbers, types and persistence of microbes that contaminate wind instruments. All previously played instruments (n = 20) harbored viable bacteria as well as mold and\\/or yeast. Reedinstruments consistently carried higher microbial loads than did flutes or trumpets. Instruments played within the previous three days bore typical mouth flora, while bacteria recovered after 72 h

Bonnie Marshall; Stuart Levy

2011-01-01

18

Microbial communities in oil-contaminated seawater  

Microsoft Academic Search

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

Shigeaki Harayama; Yuki Kasai; Akihiro Hara

2004-01-01

19

Evaluation of deep subsurface sampling procedures using serendipitous microbial contaminants as tracer organisms  

Microsoft Academic Search

Surface microbiological investigations are critically dependent on the procedures used to collect samples for study. It can be difficult to distinguish between indigenous organisms and those encountered as contaminants during the drilling process. We found that coliform bacteria contaminated drilling mud slurries. These bacteria proved useful as tracer organisms in evaluating the degree of microbial contamination accidentally encountered while drilling

Ralph E. Beeman; Joseph M. Suflita

1989-01-01

20

Detection of microbial contamination in platelets  

NASA Astrophysics Data System (ADS)

In the United States, approximately 100 patients develop fatal sepsis associated with platelet transfusions every year. Current culture methods take 24-48 hours to acquire results, which in turn decrease the shelf life of platelets. Many of the microorganisms that contaminate platelets can replicate easily at room temperature, which is the necessary storage temperature to keep platelets functional. Therefore, there is a need for in-situ quality control assessment of the platelet quality. For this purpose, a real time spectrophotometric technique has been developed. The Spectral Acquisition Processing Detection (SAPD) method, comprised of a UV-vis spectrophotometer and modeling algorithms, is a rapid method that can be performed prior to platelet transfusion to decrease the risk of bacterial infection to patients. The SAPD method has been used to determine changes in cell suspensions, based on size, shape, chemical composition and internal structure. Changes in these cell characteristics can in turn be used to determine microbial contamination, platelet aging and other physiologic changes. Detection limits of this method for platelet suspensions seeded with bacterial contaminants were identified to be less than 100 cfu/ml of sample. Bacterial counts below 1000 cfu/ml are not considered clinically significant. The SAPD method can provide real-time identification of bacterial contamination of platelets affording patients an increased level of safety without causing undue strain on laboratory budgets or personnel while increasing the time frame that platelets can be used by dramatically shortening contaminant detection time.

Berg, Tracy L.; Leparc, German; Huffman, Debra E.; Gennaccaro, Angela L.; Garcia-Lopez, Alicia; Klungness, Greta; Stephans, Christie; Garcia-Rubio, Luis H.

2005-03-01

21

Characterization of microbial contaminants in urine.  

PubMed

Modern, molecular microbiological methods were applied to urine samples from control subjects and athletes for characterization of the microbial community. High abundance of lactobacilli, enterococci, and enterobacteria was detected in urine samples, suggesting that gastrointestinal and urogenital tracts act as contamination sources. Athlete samples, but not control samples, showed an abundance of pseudomonads, a bacterial group reported to metabolize steroids. Overall, the bacteria detected are known to be capable of altering steroid profiles, emphasizing the importance of good hygiene at sampling in reliable doping control. PMID:21204289

Ojanperä, Suvi; Leinonen, Antti; Apajalahti, Juha; Lauraeus, Marko; Alaja, Susanna; Moisander, Teija; Kettunen, Anu

2010-11-11

22

Microbial contamination of gum elastic bougies.  

PubMed

The gum elastic bougie is a simple device that is used to assist in the management of the difficult intubation. It is not uncommon for a bougie to be re-used many times. This study investigated the incidence of microbial contamination of the bougies in one hospital. Potentially pathogenic organisms were identified both on the bougies and in their storage containers. This has implications for their cleaning and maintenance, and raises the question as to whether we should replace them with single-use, disposable devices. PMID:10792139

Cupitt, J M

2000-05-01

23

Seasonal variation in the microbial contamination of game carcasses in an Austrian hunting area  

Microsoft Academic Search

In 2003, 50 game carcasses (ungulates) originating from one Austrian hunting ground were subject to visual examination for (fecal) contamination of the body cavities and microbiological testing of the body cavities in order to assess variations in microbial surface contamination in the season June–August compared to October–December. No carcass tested positive for the bacterial pathogens Salmonella or Listeria. Bacterial surface

Peter Paulsen; Rudolf Winkelmayer

2004-01-01

24

Microbial contamination in 20-peso banknotes in Monterrey, Mexico.  

PubMed

The authors' aim was to isolate and identify bacteria or yeast that may be present on the surface of 20-peso banknotes from the metropolitan area of Monterrey, Mexico. They randomly studied a total of 70 20-peso banknotes for the presence of bacteria and species of Candida by conventional methods. Out of the 70 banknotes, 48 (69%) were found to be contaminated. The most prevalent species observed was Candida kruseii (19 bills, 27%) followed by Burkholderia cepacia (9 bills, 13%); 22 (31%) bills showed no growth. Of the 48 contaminated bills, four (5.7%) yielded bacteria considered pathogenic and the other 44 bills (63%) yielded bacteria considered potentially pathogenic. Eleven bills showed more than one microbial species. The results of the authors' study show that contamination occurs on paper currency in the metropolitan area of Monterrey. The authors' findings provide evidence that currency banknotes may represent a threat to human health. PMID:22984731

Rocha-Gámez, Judith; Tejeda-Villarreal, Paula Nelly; Macías-Cárdenas, Patricia; Canizales-Oviedo, Jorge; Garza-González, Elvira; Ramírez-Villarreal, Elsa Guadalupe

2012-09-01

25

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

26

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.

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

2011-01-01

27

Microbial contamination of fuel ethanol fermentations.  

PubMed

Microbial contamination is a pervasive problem in any ethanol fermentation system. These infections can at minimum affect the efficiency of the fermentation and at their worse lead to stuck fermentations causing plants to shut down for cleaning before beginning anew. These delays can result in costly loss of time as well as lead to an increased cost of the final product. Lactic acid bacteria (LAB) are the most common bacterial contaminants found in ethanol production facilities and have been linked to decreased ethanol production during fermentation. Lactobacillus sp. generally predominant as these bacteria are well adapted for survival under high ethanol, low pH and low oxygen conditions found during fermentation. It has been generally accepted that lactobacilli cause inhibition of Saccharomyces sp. and limit ethanol production through two basic methods; either production of lactic and acetic acids or through competition for nutrients. However, a number of researchers have demonstrated that these mechanisms may not completely account for the amount of loss observed and have suggested other means by which bacteria can inhibit yeast growth and ethanol production. While LAB are the primary contaminates of concern in industrial ethanol fermentations, wild yeast may also affect the productivity of these fermentations. Though many yeast species have the ability to thrive in a fermentation environment, Dekkera bruxellensis has been repeatedly targeted and cited as one of the main contaminant yeasts in ethanol production. Though widely studied for its detrimental effects on wine, the specific species-species interactions between D. bruxellensis and S. cerevisiae are still poorly understood. PMID:21770989

Beckner, M; Ivey, M L; Phister, T G

2011-08-02

28

Microbial contamination of dental unit waterlines in Istanbul, Turkey.  

PubMed

The water used in dental unit waterlines (DUWLs) acts as a coolant for the high-speed equipment and as an irrigant during dental treatments. There are kind of water tanks. DUWLs provide a favorable environment for microbial biofilm and multiplation primarily due to the high surface in the tubing and the character of fluid dynamics in narrow, smooth-walled waterlines. Biofilms can harbour opportunist pathogens such as Legionella sp., Pseudomonas sp. Several studies have shown that DUWLs have high levels of microbial contamination. Presence of high level of microbial contamination is an important problem for dentists and dental patients who are immunocompromised. We collected water samples from DUWLs of 20 private dental offices. We have determined that only 2 (3.4%) out of 59 dental unit water samples were found to meet the standard (<200 CFU.ml(-1)) for DUWLs water quality by American Dental Association (ADA). Of the 59 water samples examined, 14 (24%) were positive for Pseudomonas sp. and 18 (30.5%) were positive for fungi. The most common 14 bacterial strains and seven fungi were isolated. Of bacterial strains, 57.1% were identified: Majority of the bacterial species isolated from our samples was identified as Pseudomonas fluorescens, Pasteurella haemolytica, Photobacterium damsela, Ochrobacter anthropi, Moraxella sp., Aspergillus flavus, Penicillium expansum. Legionella sp. were not detected in all water samples. PMID:18210208

Göksay, Duygu; Cotuk, Ay?in; Zeybek, Zuhal

2008-01-22

29

Biofilms: Microbial Life on Surfaces  

PubMed Central

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 process regulated by diverse characteristics of the growth medium, substratum, and cell surface. An established biofilm structure comprises microbial cells and EPS, has a defined architecture, and provides an optimal environment for the exchange of genetic material between cells. Cells may also communicate via quorum sensing, which may in turn affect biofilm processes such as detachment. Biofilms have great importance for public health because of their role in certain infectious diseases and importance in a variety of device-related infections. A greater understanding of biofilm processes should lead to novel, effective control strategies for biofilm control and a resulting improvement in patient management.

2002-01-01

30

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

31

Modeling the frequency and duration of microbial contamination events  

Microsoft Academic Search

The frequency and duration of microbial contamination events in the environment in which ready-to-eat (RTE) foods are exposed for processing and packaging is subject to uncertainty and variability. Variability, within-model parameter uncertainty, and uncertainty regarding model selection are formally considered in modeling the frequency and duration of such contamination events by Listeria species. The estimated duration of contamination events represents

Mark R. Powell

2006-01-01

32

Perspectives on microbial cell surface display in bioremediation.  

PubMed

The display of heterologous proteins on the microbial cell surface by means of recombinant DNA biotechnologies has emerged as a novel approach for bioremediation of contaminated sites. Both bacteria and yeasts have been investigated for this purpose. Cell surface expression of specific proteins allows the engineered microorganisms to transport, bio-accumulate and/or detoxify heavy metals as well as to degrade xenobiotics. These otherwise would not be taken up and transformed by the microbial cell. This review focuses on the application of cell surface displays for the enhanced bio-accumulation of heavy metals by metal binding proteins. It also reviews the biodegradation of xenobiotics by enzymes/proteins expressed on microbial cell surfaces. PMID:18068937

Saleem, M; Brim, H; Hussain, S; Arshad, M; Leigh, M B; Zia-ul-Hassan

2007-11-07

33

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.

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

2012-01-01

34

A prospective clinical study to investigate the microbial contamination ofa needleless connector.  

PubMed

Needleless connectors, which allow direct access to intravascular catheters, are widely used in clinical practice. The benefits of these devices to healthcare workers are well documented; however, the potential risk of microbial contamination and associated infection is unclear. This clinical study evaluated microbial contamination rates for a needleless connector, Connecta Clave(R) (CC(R)), as compared to a conventional three-way tap, which was connected to the hubs of central venous catheters (CVC) immediately following insertion. Patients in the study group had CC(R) attached to the three-way taps, whereas the control group had standard entry port caps. On removal (up to 72 h) the connectors were studied for microbial contamination. There was no significant difference between the number of three-way taps contaminated on the internal surface with micro-organisms in the control group with entry port caps (19/132, 14%) compared to the group with CC(R) (18/105, 17%). Sixteen percent (27/173) of the CC(R) were contaminated with micro-organisms on the internal surfaces. The external surface of 33% (27/82) of the CC(R) silicone seals were contaminated after clinical use. Micro-organisms were also isolated from 9% (8/91) of the silicone seals after disinfection. The use of this needleless connector, compared to standard caps therefore does not appear to increase the risk of infection via the internal lumen of three-way taps. PMID:10860694

Seymour, V M; Dhallu, T S; Moss, H A; Tebbs, S E; Elliot, T S

2000-06-01

35

Environmental surface cleanliness and the potential for contamination during handwashing.  

PubMed

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 soil), bacterial, and staphylococcal load on ward handwash station surfaces, which could be touched during handwashing, is reported. Hand contact surfaces tested consisted of approximately 620 each of: faucet handles, soap dispenser activator mechanisms, and folded paper-towel dispenser exits. Failure rates in excess of benchmark clean values were higher with adenosine triphosphate assays than microbial counts. This could indicate the presence of a higher level of general organic debris (eg, skin cells) as opposed to microbial contamination or could reflect greater assay sensitivity. Faucet handles were more likely to be contaminated and be in excess of benchmark values than paper-towel dispenser exits. However, the latter are likely to be the final surface touched during the handwashing process and overall nearly 20% were above microbiologic benchmark values. Many of the organisms isolated were staphylococci and the results are discussed within the context of microbial cross-contamination and potential pathogen spread. PMID:12665742

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

2003-04-01

36

Microbial contamination of artificially incubated Greater Rhea (Rhea americana) eggs.  

PubMed

1. This paper is a report of biological agents that contaminate Greater Rhea (Rhea americana) eggs during artificial incubation. 2. The cleanliness of eggs when collected, and the period of storage prior to incubation, were investigated to assess their effects on microbial contamination and hatchability. 3. A total of 14 bacteria and 4 fungi species were isolated within the egg in the laboratory. 4. Microbial contamination was higher (24%) in very dirty eggs than in eggs which were clean or dirty (16%). Hatching success was lower (30%) for very dirty eggs, compared with 42% for clean or dirty eggs. 5. The percentage of microbial contamination of stored eggs (10%) did not differ significantly from that of non-stored ones (5%). 6. The extreme lower and upper limits of infection rate estimated for artificially incubated Greater Rhea eggs were 4% and 40%, respectively, being higher than in poultry species. 7. It is concluded that collecting eggs soon after laying will reduce the risk of microbial contamination. PMID:12964617

Lábaque, M C; Navarro, J L; Martella, M B

2003-07-01

37

Microbial contamination of continuous drip feedings.  

PubMed

We evaluated the extent and effects of bacterial contamination of an open continuous enteral feeding system. Eighty-two quantitative enteral feeding cultures and clinical data were obtained during 8 days of observation on each of 33 patients. Cultures of appropriate sites were obtained on febrile patients and compared to the enteral feeding culture. Gram negative bacilli (GNB) in the enteral feeding correlated with abdominal distension in the patients (10 of 12 patients with GNB compared to 5 of 21 without GNB; p less than 0.01). Nine of the 10 patients with GNB and distension were receiving systemic antimicrobics to which the organism was resistant. Contamination of feeding with Serratia marcescens correlated with cultures for the same organism in patients' other body sites (p less than 0.01). The feeding contaminant may have been the source of sepsis in one patient who expired from septic shock. No relationship was demonstrated between contamination and liquid stools or fever. Undiluted, canned feedings were significantly less contaminated at 24 hr (15%) than those requiring mixing of powder (94%) (p less than 0.0001). The canned feedings grew primarily enteric organisms, whereas the powder feedings grew flora typically resident on the skin. Mixing or diluting feedings appears to represent an increased risk of contamination. Growth of GNB may produce adverse effects. Further investigation into methods to limit contamination and growth is warranted. PMID:2494363

Freedland, C P; Roller, R D; Wolfe, B M; Flynn, N M

38

Microbial contamination detection at low levels by [125]I radiolabeling  

NASA Astrophysics Data System (ADS)

Contamination of mission spacecraft is an ongoing issue. A broad diversity of microorganisms have been detected in clean rooms where spacecraft are assembled. Some of which, depicted as oligotroph, are of special regard, as they are capable of colonizing inorganic surfaces like metal, and have been shown to be a concern for forward contamination of pristine celestial bodies. Currently, the NASA standard assay is the only approved assay intended for the enumeration of spores and heterotrophic microbial populations. However, culture-based microbial detection methods underestimate the viable microbial population. More recently, adenosine triphosphate (ATP) bioluminescence and limulus amebocyte lysate (LAL) assays, which employ measure-ments of selected metabolic products as a proxy of biomass, have been used successfully to circumvent the necessity of the growth of microorganisms in order to estimate the biodurdens associated with spacecraft assembly facility. However, these methods have limitation in the amount of cells that can be detected, i.e., 103 cells, and the type of microorganisms respec-tively. This work seeks to develop a new highly sensitive method for the determination of bioburdens (and the detection of microorganisms and life) that is independant of the type of organism while preserving a good turn-around time for analysis for planetary protection purposes. The assay is based on the detection of the organism's protein by labeling them by radioiodination, 125 I, of aromatic rings on tyrosine amino acids residues. Radiolabeling techniques are inherently sensitive and 125 I, in particular, benefits from a 60 day half-life, providing greater activity and signal per unit number of labels. Furthermore, microorganisms can contain over 50% of protein by dry weight. Thus, just one label per protein increases the sensitivity, compared to the ATP and LAL assays, by one and three orders of magnitude by using standard detection methods and the use of multiphoton detection (MPD), respectively. Therefore this assay enables the detection to lower levels than previously possible, down to single cells. The method has also applicability for testing returned samples hardware and for the testing sterilization methods as well as other Astrobiological applications. Future work could extend to species such as viruses and prions.

Summers, David; Karouia, Fathi

39

Microbial contamination of stored hydrocarbon fuels and its control  

Microsoft Academic Search

The major microbial problem in the petroleum refining industry is contamination of stored products, which can lead to loss of product quality, formation of sludge and deterioration of pipework and storage tanks, both in the refinery and at the end-user. Three major classes of fuel are discussed in this article - gasoline, aviation kerosene and diesel, corresponding to increasingly heavy

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

1999-01-01

40

The potential for catheter microbial contamination from a needleless connector  

Microsoft Academic Search

Needleless connectors have been widely introduced into clinical practice to allow the connection of syringes and luers to peripheral and central vascular catheters. The potential for microbial contamination of catheters via these devices is currently unclear. A recently introduced connector, the ‘Connecta Clave’, was assessed by various in-vitro methods. The ‘Connecta Clave’ is specifically devised to separate external components from

J. D. Brown; H. A. Moss; T. S. J. Elliott

1997-01-01

41

Microbial contamination of ‘sterile water’ used in Japanese hospitals  

Microsoft Academic Search

We examined the following samples of water from 10 hospitals for microbial contamination: water obtained using an ultra filtration system (UF water), a reverse osmosis system (RO water), a water distillation system (distilled water) and tap water. UF water and RO water are used for handwashing before surgery, and distilled water for the preparation of drugs. All 10 samples of

S. Oie; M. Oomaki; K. Yorioka; T. Tatsumi; M. Amasaki; T. Fukuda; H. Hakuno; K. Nagano; M. Matsuda; N. Hirata; N. Miyano; A. Kamiya

1998-01-01

42

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

43

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

44

Effects of Subsurface Microbial Ecology on Geochemical Evolution of a Crude-Oil Contaminated Aquifer  

NASA Astrophysics Data System (ADS)

We have identified several subsurface habitats for microorganisms in a crude oil contaminated located near Bemidji, Minnesota. These aquifer habitats include: 1) the unsaturated zone contaminated by hydrocarbon vapors, 2) the zones containing separate-phase crude oil, and 3) the aqueous-phase contaminant plume. The surficial glacial outwash aquifer was contaminated when a crude oil pipeline burst in 1979. We analyzed sediment samples from the contaminated aquifer for the most probable numbers of aerobes, iron reducers, fermenters, and three types of methanogens. The microbial data were then related to gas, water, and oil chemistry, sediment extractable iron, and permeability. The microbial populations in the various contaminated subsurface habitats each have special characteristics and these affect the aquifer and contaminant chemistry. In the eight-meter-thick, vapor-contaminated vadose zone, a substantial aerobic population has developed that is supported by hydrocarbon vapors and methane. Microbial numbers peak in locations where access to both hydrocarbons and nutrients infiltrating from the surface is maximized. The activity of this population prevents hydrocarbon vapors from reaching the land surface. In the zone where separate-phase crude oil is present, a consortium of methanogens and fermenters dominates the populations both above and below the water table. Moreover, gas concentration data indicate that methane production has been active in the oily zone since at least 1986. Analyses of the extracted separate-phase oil show that substantial degradation of C15 -C35 n-alkanes has occurred since 1983, raising the possibility that significant degradation of C15 and higher n-alkanes has occurred under methanogenic conditions. However, lab and field data suggest that toxic inhibition by crude oil results in fewer acetate-utilizing methanogens within and adjacent to the separate-phase oil. Data from this and other sites indicate that toxic inhibition of acetoclastic methanogenesis in the proximity of separate phase contaminant sources may result in build-up of acetate in contaminant plumes. Within the aqueous-phase contaminant plume steep vertical hydrocarbon concentration gradients are associated with sharp transitions in the dominant microbial population. In the 20 years since the aquifer became contaminated, sediment iron oxides have been depleted and the dominant physiologic type has changed in areas of high contaminant flux from iron reducing to methanogenic. Thus, methanogens are found in high permeability horizons down gradient from the oil while iron reducers persist in low permeability zones. Expansion of the methanogenic zone over time has resulted in a concomitant increase in the aquifer volume contaminated with the highest concentrations of benzene and ethylbenzene.

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

2001-12-01

45

Control of microbial contamination with commercially available cleaning solutions.  

PubMed

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

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

1992-02-01

46

Removal of paper microbial contamination by atmospheric pressure DBD discharge  

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

47

Microbial contamination of cutting fluids and associated hazards  

Microsoft Academic Search

In this paper, an experimental investigation into the microbial contamination of cutting fluids is presented. The paper confirms the laboratory based results of the fluid biocontamination by culture and identification of the micro-organisms, and their ability to survive in the workshop fluid systems. Direct and\\/or indirect associations of the identified micro-organisms with the potential health hazards are pointed out.

S. M. A Suliman; M. I Abubakr; E. F Mirghani

1997-01-01

48

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

49

Influence of root-exudates concentration on pyrene degradation and soil microbial characteristics in pyrene contaminated soil.  

PubMed

The effect of ryegrass (Lolium perenne L.) root-exudates concentration on pyrene degradation and the microbial ecological characteristics in the pyrene contaminated soil was investigated by simulating a gradually reducing concentration of root exudates with the distance away from root surface in the rhizosphere. Results showed that, after the root-exudates were added 15 d, the pyrene residue in contaminated soil responded nonlinearly in the soils with the same pyrene contaminated level as the added root-exudates concentration increased, which decreased first and increased latter with the increase of the added root-exudates concentration. The lowest pyrene concentration appeared when the root exudates concentration of 32.75 mg kg(-1) total organic carbon (TOC) was added. At the same time, changes of microbial biomass carbon (MBC, C(mic)) and microbial quotient (C(mic)/C(org)) were opposite to the trend of pyrene degradation as the added root-exudates concentration increased. Phospholipid fatty acid (PLFA) analysis revealed that bacteria was the dominating microbial community in pyrene contaminated soil, and the changing trends of pyrene degradation and bacteria number were the same. The changing trend of endoenzyme-dehydrogenase activity was in accordance with that of soil microbe, indicating which could reflect the quantitative characteristic of detoxification to pyrene by soil microbe. The changes in the soils microbial community and corresponding microbial biochemistry characteristics were the ecological mechanism influencing pyrene degradation with increasing concentration of the added root-exudates in the pyrene contaminated soil. PMID:22520968

Xie, Xiao-mei; Liao, Min; Yang, Jing; Chai, Juan-juan; Fang, Shu; Wang, Run-han

2012-04-20

50

MICROBIAL INTERACTIONS WITH PESTICIDES IN ESTUARINE SURFACE SLICKS  

EPA Science Inventory

Estuarine surface films from Escambia Bay, Florida, and adjacent waters were sampled by using the membrane adsorption technique to enumerate microbial populations. Samples of the upper 10 micrometers of estuarine surface films yielded microbial populations. These populations were...

51

Effect of arsenic contamination on microbial biomass and its activities in arsenic contaminated soils of Gangetic West Bengal, India  

Microsoft Academic Search

A study was conducted to see the effect of arsenic contamination on soil quality indicators, viz., microbial biomass, soil respiration, fluorescein diacetate and dehydrogenase (DHG) activity in arsenic contaminated soils of West Bengal. All the parameters were significantly and negatively correlated with all the form of arsenic (bioavailable and total) but the microbial metabolic quotient was significantly and positively correlated

A. K. Ghosh; P. Bhattacharyya; R. Pal

2004-01-01

52

MICROBIAL CONTAMINATION IN LAKE PONTCHARTRAIN BASIN AND BEST MANAGEMENT PRACTICES ON MICROBIAL CONTAMINATION REDUCTION  

Microsoft Academic Search

The Lake Pontchartrain Basin is a complex system of physical and biological elements. Due to the actions of man, the Basin's ecosystem has changed significantly over the past half century. These changes have impaired water quality and habitats throughout the Pontchartrain Basin. Recreational activities including swimming have been banned in areas of the lake. This paper discusses sources of microbial

Andrew J. Englande Jr; Guang Jin; Carlton Dufrechou

2002-01-01

53

Microbial contamination of "in use" bar soap in dental clinics.  

PubMed

Bar soap from 18 different dental clinics were investigated for microbial contamination, while it was "in-use". Of the 32 samples obtained from the bar soap, 100% yielded positive culture. A total of 8 different genera of organisms were isolated. Each bar soap was found to harbor 2-5 different genera of micro organisms. Heavily used soap had more micro organisms compared to less used soap. The microbial load of the "in-use" bar soap constituted a mixed flora of gram positive, gram negative, aerobes, anaerobes, and fungi. The results indicate that the bar soap under "in-use" condition is a reservoir of microorganisms and handwashing with such a soap may lead to spread of infection. PMID:17051871

Hegde, P P; Andrade, A T; Bhat, K

54

Microbial contamination of orthodontic buccal tubes from manufacturers.  

PubMed

This study aimed to test the sterility of new unused orthodontic buccal tubes received from manufacturers. Four different types of buccal tubes were used straight from the manufactures package without any additional sterilizing step. Of these buccal tubes tested, three genera of bacteria, implicated as opportunistic pathogens, namely Micrococcus luteus, Staphylococcus haemolyticus and Acinetobacter calcoaceticus were recovered from these buccal tubes. Our data showing microbial contamination on buccal tubes highlights the need of sterilization before clinical use. We also suggest that manufacturers should list the sterility state of orthodontic buccal tubes on their packaging or instructions stating the need for sterilization. PMID:20957099

Purmal, Kathiravan; Chin, Shenyang; Pinto, John; Yin, Wai-Fong; Chan, Kok-Gan

2010-09-16

55

DETECTION OF FECAL\\/INGESTA CONTAMINANTS ON POULTRY PROCESSING EQUIPMENT SURFACES BY VISIBLE AND NEAR-INFRARED REFLECTANCE SPECTROSCOPY  

Microsoft Academic Search

Visible and near-infrared (NIR) spectra and samples for laboratory microbial analysis were acquired of fecal contaminants, ingesta contaminants, and bare processing equipment surfaces (rubber and stainless steel) in a commercial poultry processing plant. Spectra were analyzed in the visible region of 450 to 748 nm and the NIR region of 920 to 1680 nm and microbial sampling for Enterobacteriaceae counts

K. Chao; X. Nou; Y. Liu; M. S. Kim; D. E. Chan; C.-C. Yang; J. Patel; M. Sharma

56

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.

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

2011-01-01

57

Microbial Ecology of the Vadose Zone in the Vicinity of Residual Crude-Oil Contamination  

NASA Astrophysics Data System (ADS)

We characterized the microbial population in an 8-meter-thick, hydrocarbon-contaminated vadose zone using Most Probable Number (MPN) estimates for four physiologic types: aerobes, heterotrophic fermenters, iron-reducers and methanogens. The site is a surficial sand and gravel aquifer near Bemidji, MN, that was contaminated in 1979 when crude oil infiltrated the subsurface from a broken pipeline. Substantial liquid and vapor-phase petroleum hydrocarbons remain in the vadose zone. We examined three vadose-zone profiles located in: 1) the residual oil, 2) a vapor-contaminated area, and 3) the capillary fringe above the contaminated aquifer. In the residual oil ~100 methanogens per gram dry weight of sediment (g-1) are present throughout the profile, and fermenter numbers g-1 are 10,000 times those of iron-reducers, suggesting that methanogenesis is now the dominant degradation process. Analyses of extracted oil from these sediments show that substantial degradation of C15 -C35 n-alkanes has occurred since 1983. Moreover, gas concentration measurements indicate that methane production in this location has been active since at least 1986, raising the possibility that significant degradation of C15 and higher n-alkanes has occurred under methanogenic conditions. In the vapor-contaminated profile, aerobe numbers g-1 are 10,000 times higher than uncontaminated background values. Methanotrophic activity also was detected in laboratory incubations of these sediments. Apparently, a substantial microbial population has developed that is supported by the hydrocarbon vapors and methane. Downgradient from the oil, where groundwater is contaminated but no hydrocarbon vapors are detected, fermenter and aerobe numbers g-1 above the capillary fringe match those of uncontaminated sediments (100-1,000 g-1). Within the capillary fringe, numbers increase rapidly with depth to values typically found in the contaminated saturated zone. In the vadose zone profiles with significant hydrocarbon sources from residual oil and vapors, microbial populations are typically 10-100 times higher than in the underlying contaminated saturated zone. Moreover, in areas with residual oil, numbers g-1 increase significantly upward toward the land surface. This pattern suggests that supply of an unknown, essential nutrient from the land surface may be facilitating growth in the hydrocarbon-contaminated vadose zone. In contrast, at the location with no significant vadose zone hydrocarbons, numbers g-1 in the capillary fringe are less than or equal to those in the contaminated saturated zone below.

Bekins, B. A.; Godsy, E. M.; Warren, E.; Hostettler, F. D.

2001-05-01

58

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.

Gough, Heidi L; Stahl, David A

2011-01-01

59

Evidence for microbial enhanced electrical conductivity in hydrocarbon-contaminated sediments  

NASA Astrophysics Data System (ADS)

Bulk electrical conductivity of sediments during microbial mineralization of diesel was investigated in a mesoscale laboratory experiment consisting of biotic contaminated and uncontaminated columns. Population numbers of oil degrading microorganisms increased with a clear pattern of depth zonation within the contaminated column not observed in the uncontaminated column. Microbial community structure determined from ribosomal DNA intergenic spacer analysis showed a highly specialized microbial community in the contaminated column. The contaminated column showed temporal increases in bulk conductivity, dissolved inorganic carbon, and calcium, suggesting that the high bulk conductivity is due to enhanced mineral weathering from microbial activity. The greatest change in bulk conductivity occurred in sediments above the water table saturated with diesel. Variations in electrical conductivity magnitude and microbial populations and their depth distribution in the contaminated column are similar to field observations. The results of this study suggest that geophysical methodologies may potentially be used to investigate microbial activity.

Atekwana, Estella A.; Atekwana, Eliot A.; Werkema, D. Dale; Allen, Jonathan P.; Smart, Laura A.; Duris, Joseph W.; Cassidy, Daniel P.; Sauck, William A.; Rossbach, Silvia

2004-12-01

60

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.

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

2003-01-01

61

Technology Reference Guide for Radiologically Contaminated Surfaces.  

National Technical Information Service (NTIS)

The U.S. Environmental Protection Agency (EPA), Office of Radiation and Indoor Air (ORIA) developed this Technology Reference Guide For Radiologically Contaminated Surfaces to help identify surface decontamination technologies that can effectively remove ...

E. Feltcorn

2006-01-01

62

Geoelectrical Evidence of Microbial Degradation of Diesel Contaminated Sediments  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

63

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...

64

A prospective clinical study toinvestigate the microbial contamination ofa needleless connector  

Microsoft Academic Search

Needleless connectors, which allow direct access to intravascular catheters, are widely used in clinical practice. The benefits of these devices to healthcare workers are well documented; however, the potential risk of microbial contamination and associated infection is unclear. This clinical study evaluated microbial contamination rates for a needleless connector, Connecta Clave® (CC®), as compared to a conventional three-way tap, which

V. M. Seymou; T. S. Dhallu; H. A. Mos; S. E. Tebb; T. S. J. Elliot

2000-01-01

65

Rapid and robust detection methods for poison and microbial contamination.  

PubMed

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 the rapid quantification of a wide range of chemical and microbial contaminations using a simple instrument. Within the testing procedure, we used a multichannel, multisample, UV-vis spectrophotometer/fluorometer that employs two frequencies of light simultaneously to interrogate the sample. We present new enzyme- and dye-based methods to detect (di)ethylene glycol in consumables above 0.1 wt % without interference and alcohols above 1 ppb. Using DNA intercalating dyes, we can detect a range of pathogens ( E. coli , Salmonella , V. Cholera, and a model for Malaria) in water, foods, and blood without background signal. We achieved universal scaling independent of pathogen size above 10(4) CFU/mL by taking advantage of the simultaneous measurement at multiple wavelengths. We can detect contaminants directly, without separation, purification, concentration, or incubation. Our chemistry is stable to ± 1% for >3 weeks without refrigeration, and measurements require <5 min. PMID:22630610

Hoehl, Melanie M; Lu, Peter J; Sims, Peter A; Slocum, Alexander H

2012-06-15

66

Enzyme-enabled responsive surfaces for anti-contamination materials.  

PubMed

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

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

2013-02-09

67

Microbial Monitoring of Surface Water in South Africa: An Overview  

PubMed Central

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

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

2012-01-01

68

Microbial cross-contamination by airborne dispersion and contagion during defeathering of poultry  

Microsoft Academic Search

1. A readily identifiable strain of Escherichia coli K12 was used as a 'marker' organism to determine the sources, routes and patterns of microbial cross-contamination during mechanical defeathering of broiler chicken carcases. 2. Inoculation of scald water with the marker organism led to a relatively even pattern of carcase contamination during subsequent defeathering. Microbial cross-contamination was greater by this route

V. M. Allen; M. H. Hinton; D. B. Tinker; C. Gibson; G. C. Mead; C. M. Wathes

2003-01-01

69

Dirty Glass: Rendering Contamination on Transparent Surfaces  

Microsoft Academic Search

Rendering of clean transparent objects has been well studied in computer graphics. However, real-world transpar- ent objects are seldom clean—their surfaces have a variety of contaminants such as dust, dirt, and lipids. These contaminants produce a number of complex volumetric scattering effects that must be taken into account when creating photorealistic renderings. In this paper, we take a step toward

Jinwei Gu; Ravi Ramamoorthi; Peter N. Belhumeur; Shree K. Nayar

2007-01-01

70

Rapid checks on sanitized surfaces ensure microbial-free food processing in industry  

Microsoft Academic Search

An effective monitoring of microbial contamination on surfaces and plant components is of fundamental importance in food industry, refectories and work canteens to ensure products quality and safety. The classic microbiological tests inform about the sanitization procedures effectiveness at least after 1-2 days, the rapid luminescent ATP assay after about 5 minutes, on site. In this study the presence of

Pasquale CAPUTO; Elida FERRI; Gianluca GUARNIERI; Graziella LASI; Simone GOZZI; Fabio Milesi; Stefano GIROTTI

71

An imaging contamination monitoring system for surfaces  

Microsoft Academic Search

A novel system for monitoring surfaces for radioactive contamination has been developed. The system uses audible and visual identification methods to provide natural coactivation clues to an operator, resulting in enhanced sensitivity to areas of surface contamination. The system utilizes position-sensing proportional counter detectors, and includes a head-mounted display that provides the user with a real-time, three-dimensional image to allow

J. J. Shonka; D. M. DeBord; T. E. Bennett

1996-01-01

72

High levels of microbial contamination of vegetables irrigated with wastewater by the drip method.  

PubMed Central

The public health aspects of the use of wastewater in agriculture and the effects of the drip irrigation method on the contamination of vegetables were studied. The method used was to simulate enteric microorganisms' dissemination by contaminated irrigation water in the field. The vegetables were irrigated with an effluent inoculated with a high titer of traceable microorganisms: poliovirus vaccine and a drug-resistant Escherichia coli. The dissemination of the marker organisms in the field was followed, and the effects of certain manipulations of the drip irrigation method on the contamination of the crops by the effluent were examined. It was shown that drip irrigation under plastic sheet cover with the drip lines placed either on the soil surface or buried at a depth of 10 cm significantly reduced crop contamination from inoculated irrigation water even when massive doses of bacteria and viruses were used. The microbial contamination was found to persist in the irrigation pipes and in the soil for at least 8 and 18 days, respectively. The data indicate that the recovery of the marker organisms was affected by soil texture and environmental conditions.

Sadovski, A Y; Fattal, B; Goldberg, D; Katzenelson, E; Shuval, H I

1978-01-01

73

Microbial influences on inorganic solute mobilization and transport in an oil contaminated aquifer  

SciTech Connect

Microbial degradation of hydrocarbons in a shallow sand and gravel aquifer contaminated with petroleum results in a distinctive inorganic solute plume that mimics the plume of organic constituents. At the USGS Bemidji, MN research site, microbial control of the geochemical environment beneath a floating pool of oil has resulted in a highly reducing groundwater zone along the major flow path. Within this region, where the fugacity of oxygen is extremely low, microbes utilize naturally occurring iron and manganese minerals as the terminal electron acceptor for the oxidation of hydrocarbons. This results in an increase in ferrous iron concentration from background levels of less than 0.05 mg/l to over 50 mg/l along about 40 meters of the flow path. Dissolved iron concentration remains elevated, and transport of iron occurs, as long as oxygen fugacity remains low. In the reducing zone, petroleum degrading microbes were found to colonize fresh silicate surfaces. Extracellular byproducts of metabolism, such as organic acids, are found in the contaminated groundwater, and these compounds may be present at very high levels near the attached microbial colonies, resulting in a highly reactive micro-environment. Where attached microbial colonies were found, rapid chemical weathering of both quartz and feldspar occurred, producing distinctive and pronounced chemical etching. Dissolved silica is apparently meta-stable in the highly reducing, organic-rich groundwater, and dissolved silica concentration is near equilibrium with amorphous silica gel. Silica is transported along the major flow path until oxygen fugacity increases, and degradation of organic carbon accelerates. Here silica precipitates as silica plastering on silicate minerals. Silica precipitation is coincident with the iron precipitation, and the two processes may be linked, although iron-silicate clays have not been isolated from the site.

Bennett, P.C.; Hiebert, F.K. (Univ. of Texas, Austin, TX (United States). Dept. of Geological Sciences); Baedecker, M.J. (Geological Survey, Reston, VA (United States))

1992-01-01

74

Faecal contamination of greywater and associated microbial risks.  

PubMed

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 0.04 g person(-1) day(-1). Prevalence of pathogens in the population and the faecal load were used to form the basis of a screening-level quantitative microbial risk assessment (QMRA) that was undertaken for rotavirus, Salmonella typhimurium, Campylobacter jejuni, Giardia lamblia and Cryptosporidium parvum. The different exposure scenarios simulated--direct contact, irrigation of sport fields and groundwater recharge--gave unacceptably high rotavirus risks (0.04 < Pinf < 0.60) despite a low faecal load. The poor reduction of somatic coliphages, which were used as a virus model, in the treatment was one main reason and additional treatment of the greywater is suggested. Somatic coliphages can under extreme circumstances replicate in the wastewater treatment system and thereby underestimate the virus reduction. An alternative QMRA method based on faecal enterococci densities estimated similar risks as for rotavirus. Growth conditions for Salmonella in greywater sediments were also investigated and risk modelling based on replication in the system increased the probability of infection from Salmonella 1000-fold, but it was still lower than the risk of a rotavirus infection. PMID:12688699

Ottoson, Jakob; Stenström, Thor Axel

2003-02-01

75

A Model to Predict Microbial Contamination of Blanched Spinach  

Microsoft Academic Search

To predict the microbial concentration of blanched spinach a mathematical model was set up which takes microbial heat resistance into account. Two versions describe microbial counts of vegetative cells and of endospores in blanched spinach as a function of operating conditions during batch and continuous blanching. The predictive model was verified in several batch blanching experiments. Although based on simplified

E. Mayer-Miebach; B. Zanoni; W. E. L. Spiess

1997-01-01

76

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

National Technical Information Service (NTIS)

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 par...

J. H. Cushman

2000-01-01

77

DYNAMICS OF COUPLED CONTAMINANT AND MICROBIAL TRANSPORT IN HETEROGENEOUS POROUS MEDIA  

EPA Science Inventory

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

78

DYNAMICS OF COUPLED CONTAMINANT AND MICROBIAL TRANSPORT IN HETEROGENEOUS POROUS MEDIA  

EPA Science Inventory

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

79

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...

80

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

Microsoft Academic Search

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

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

1999-01-01

81

Soil ventilation: Effects on microbial populations in gasoline-contaminated subsurface soils  

Microsoft Academic Search

Short- and long-term effects of vapor extraction (VE) in an unsaturated subsurface soil and in situ biodegradation of gasoline were evaluated in a field study. Subsurface temperature, moisture, solid- and gas-phase contaminant levels, atmospheric gases, nutrient levels, and microbial population densities were measured during and after soil VE for 462 d. Microbial activity, based on in situ Oâ consumption rates,

W. J. Hickey

1995-01-01

82

Early detection of microbial contamination in processed tomatoes by electronic nose  

Microsoft Academic Search

Microbial contamination can easily affect processed tomato, thus determining both organoleptic adulterations and potential health risks for customers. Innovative techniques for a rapid and reliable diagnose of spoilage, such as electronic nose technology, are highly requested in order to guarantee food safety and to improve production. In this work canned peeled tomatoes were artificially spoiled with different kinds of microbial

I. Concina; M. Falasconi; E. Gobbi; F. Bianchi; M. Musci; M. Mattarozzi; M. Pardo; A. Mangia; M. Careri; G. Sberveglieri

2009-01-01

83

Microbial contamination and preservative capacity of some brands of cosmetic creams  

Microsoft Academic Search

Purpose: Cosmetic and topical products need not be sterile but may contain low levels of microbial load during use. This study was conducted to determine and compare the level and type of microbial contaminants in commercial cosmetic products sold in the market and a laboratory prepared aqueous cream and their preservative capacities while in use. Methods: Ten brands of commercially

Peter G Hugbo; Anthony O Onyekweli

84

Altered Geophysical Response Reflects Changes in Microbial Community Structure in Petroleum Contaminated Sediments  

NASA Astrophysics Data System (ADS)

The microbial diversity of a petroleum contaminated site was investigated in order to further elucidate biogeophysical relationships of the subsurface. Increases in the sediment bulk conductivity at hydrocarbon contaminated sites have been suggested to result from enhanced mineral weathering due to increased microbial activity within the free-phase contamination zone. Therefore, our main objective was to characterize the microbial community structure in zones of higher and lower conductivity. Culture-independent 16S rRNA gene libraries were constructed using sediment samples collected from the contaminated and background sites. Diversity indices indicated that the microbial community at the contaminated site contained fewer, more dominant populations, whereas the microbial community at the background site was much more diverse. This confirms the notion that environmental disturbances decrease the diversity of microbial communities. Pairwise comparisons of the microbial communities revealed that the communities from the contaminated versus background sites were significantly different. Phylogenetic analysis demonstrated that the largest proportion of the microbial community from within the petroleum contaminated zone was affiliated with members of the Proteobacteria division, while the largest proportion from the vadose zone and background sediments were affiliated with members of the Acidobacteria division. Specific microbial populations detected only within the petroleum contaminated zone were related to the dissimilatory iron reducing bacteria (DIRB), including Desulfitobacterium and Rhodoferax ferrireducens. Rhodoferax ferrireducens is known to reduce Fe(III) by direct contact, which could conceivably enhance mineral dissolution. Other significant populations were affiliated with the syntrophic bacteria Syntrophus and Pelotomaculum. Members of the Syntrophus genus are characteristically found in methanogenic environments, suggesting methanogenesis as the dominant terminal electron accepting process (TEAP) within the anaerobic petroleum contaminated zone. Moreover, a variety of methylo- and methanotrophic bacteria were found to be present around the plume. Thus, the microbial communities in and around the aged underground petroleum plume have become highly adapted to the available carbon source (petroleum hydrocarbons), and strongly influence the geophysical and geochemical surroundings through their catabolic activities. These results suggest that changes in microbial community structures parallel changes in the geophysical properties of contaminated sediments and provide strong evidence favoring the use of geoelectrical measurements for the monitoring of natural or engineered bioremediation processes.

Allen, J. P.; Atekwana, E. A.; Rossbach, S.

2006-05-01

85

Surface contamination analysis technology team overview  

NASA Astrophysics Data System (ADS)

The surface contamination analysis technology (SCAT) team was originated as a working roup of NASA civil service, Space Shuttle contractor, and university groups. Participating members of the SCAT Team have included personnel from NASA Marshall Space Flight Center's Materials and Processes Laboratory and Langley Research Center's Instrument Development Group; contractors-Thiokol Corporation's Inspection Technology Group, AC Engineering support contractor, Aerojet, SAIC, and Lockheed MArtin/Oak Ridge Y-12 support contractor and Shuttle External Tank prime contractor; and the University of Alabama in Huntsville's Center for Robotics and Automation. The goal of the SCAT team as originally defined was to develop and integrate a multi-purpose inspection head for robotic application to in-process inspection of contamination sensitive surfaces. One area of interest was replacement of ozone depleting solvents currently used for surface cleanliness verification. The team approach brought together the appropriate personnel to determine what surface inspection techniques were applicable to multi-program surface cleanliness inspection. Major substrates of interest were chosen to simulate space shuttle critical bonding surface or surfaces sensitive to contamination such as fuel system component surfaces. Inspection techniques evaluated include optically stimulated electron emission or photoelectron emission; Fourier transform infrared spectroscopy; near infrared fiber optic spectroscopy; and, ultraviolet fluorescence. Current plans are to demonstrate an integrated system in MSFC's Productivity Enhancement Complex within five years from initiation of this effort in 1992. Instrumentation specifications and designs developed under this effort include a portable diffuse reflectance FTIR system built by Surface Optics Corporation and a third generation optically stimulated electron emission system built by LaRC. This paper will discuss the evaluation of the various techniques on a number of substrate materials contaminated with hydrocarbons, silicones, and fluorocarbons. Discussion will also include standards development for instrument calibration and testing.

Burns, H. Dewitt

1996-11-01

86

Microbial community structure in a shallow hydrocarbon-contaminated aquifer associated with high electrical conductivity  

NASA Astrophysics Data System (ADS)

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 hydrocarbons by resident microbial communities causes a local increase in organic acid concentrations, which in turn cause an increase in native mineral weathering and a concurrent increase in the bulk electrical conductivity of soil. Microbial community structure was analyzed using a 96-well most probable number (MPN) method and rDNA intergenic spacer region analysis (RISA). Microbial community structure was found to change in the presence of hydrocarbon contaminants and these changes were consistently observed in regions of high electrical conductivity. We infer from this relationship that geophysical methods for monitoring the subsurface are a promising new technology for monitoring changes in microbial community structure and simultaneous changes in geochemistry that are associated with hydrocarbon degradation.

Duris, J. W.; Rossbach, S.; Atekwana, E. A.; Werkema, D., Jr.

2003-04-01

87

Determination of microbial carbon sources in petroleum contaminated sediments using molecular 14C analysis.  

PubMed

Understanding microbial carbon sources is fundamental to elucidating the role of microbial communities in carbon cycling and in the biodegradation of organic contaminants. Because the majority of anthropogenic contaminants are either directly or indirectly derived from fossil fuels that are devoid of 14C, radiocarbon can be used as a natural inverse tracer of contaminant carbon in the contemporary environment. Here, 14C analysis of individual microbial phospholipid fatty acids (PLFA) was used to characterize the carbon sources utilized bythe active microbial community in salt marsh sediments contaminated by the Florida oil spill of 1969 in Wild Harbor, West Falmouth, MA. A specific goal was to determine whether this community is actively degrading petroleum residues that persist in these sediments. The delta14C values of microbial PLFA in all sediment horizons (contaminated and noncontaminated) matched the delta14C of the total sedimentary organic carbon after petroleum removal, indicating that no measurable metabolism of petroleum residues was occurring. This result agrees with ancillary data such as the delta13C content and distribution of PLFA, and the residual hydrocarbon composition determined by comprehensive two-dimensional gas chromatography (GCxGC) analysis. We hypothesize that microbes have chosen to respire the natural organic matter rather than the residual petroleum hydrocarbons because the former is more labile. Future efforts directed at determining indices of microbial degradation of petroleum hydrocarbons should consider competition with natural organic matter. PMID:15884348

Slater, Gregory F; White, Helen K; Eglinton, Timothy I; Reddy, Christopher M

2005-04-15

88

Influence of Microbial Iron and Nitrate Reduction on Subsurface Iron Biogeochemistry and Contaminant Metal Mobilization  

SciTech Connect

Although toxic metal and radionuclide contaminants can not be destroyed, their toxicity and mobility can be dramatically altered by microbial activity. In addition to toxic metals, many contaminated sites contain both iron-containing minerals and co-contaminants such as nitrate NO{sub 3}{sup -}. Successful implementation of metal and radionuclide bioremediation strategies in such environments requires an understanding of the complex microbial and geochemical interactions that influence the redox speciation and mobility of toxic metals. Our specific objectives have been to (1) determine the effect of iron oxide mineral reduction on the mobility of sorbed, representative toxic metals (Zn{sup 2+}), (2) study the biogeochemical interactions that may occur during microbial reduction of NO{sub 3}{sup -} and iron oxide minerals, and (3) evaluate the kinetics of NO{sub 3}{sup -}-dependent, microbial oxidation of ferrous iron (Fe{sup 2+}).

Flynn W. Picardal

2002-04-10

89

An imaging contamination monitoring system for surfaces  

SciTech Connect

A novel system for monitoring surfaces for radioactive contamination has been developed. The system uses audible and visual identification methods to provide natural coactivation clues to an operator, resulting in enhanced sensitivity to areas of surface contamination. The system utilizes position-sensing proportional counter detectors, and includes a head-mounted display that provides the user with a real-time, three-dimensional image to allow for instant recognition of surface contamination. This visual information is augmented with audio input in the form of background-subtracted stereo clicks. Time-stamped survey data is stored for later retrieval, providing for additional analysis using a digital imaging workstation. The system is motorized to provide constant speed during surveys, and surveys are recorded with a video camera to allow identification of locations of contamination using the time index from the stored data. The system has been used to conduct surveys at several facilities throughout the southeast, including the Y-12 and K-25 sites in Oak Ridge, Tennessee, and EPA facilities in Montgomery, Alabama. It was demonstrated that the system could perform surveys at much greater rates than with conventional methods, with equal or better detection performance and with documentation so complete that an entire survey could be reexamined at a later date with the reviewer able to see what the original surveyor saw, including display indications and the surface that was monitored.

Shonka, J.J.; DeBord, D.M.; Bennett, T.E. [Shonka Research Associates, Marietta, GA (United States)] [and others

1996-06-01

90

Contamination of optical surfaces in Earth orbit  

NASA Astrophysics Data System (ADS)

Glass and glass ceramic samples exposed to the low earth orbit environment for approximately 5.5 years on the Long Duration Exposure Facility (LDEF) were found to display limited degradation in optical transmission. Commercial optical quality fused silica samples display decreases in transmission in the 200 to 400 nm wavelength region, and this degradation appears to be a consequence of surface contamination. The contamination, found only on internal surfaces of samples, was measured by medium energy backscattering spectrometry and found to be primarily carbon. Additional thin film contamination by a species with atomic mass near 64, which was present at the level of about 8 x 10 exp 14/sq. cm has not been identified. These observations are consistent with the interpretation that organic binders used in the black absorbing paint (Chem Glaze Z-306) inside the sample holding tray were concentrated in the vicinity of the samples and photolytically cracked by solar UV radiation. The resulting decomposition products were deposited on the interior sample surface and gave rise to the optical transmission loss. No detectable contamination was observed on the external or space exposed surface of the samples. No measurable damage was detected which could be attributed to the direct action of gamma or UV radiation on the glass samples. These results emphasize the need for special precautions in the preparation of spacecraft carrying precision optical components on long duration missions.

Kinser, Donald L.; Weller, Robert A.; Mendenhall, M. H.; Wiedlocher, D. E.; Nichols, R.; Tucker, D.; Whitaker, A.

1992-01-01

91

Suction methods for assessing contamination on surfaces  

Microsoft Academic Search

Suction sampling techniques are widely used to assess particulate contamination levels on domestic and occupational surfaces such as floor coverings, but their use for dermal exposure assessment has, to date, been limited. This paper reviews the sampling techniques commonly employed and summarises the range of sampling efficiencies reported in the literature. As there are an extremely large number of key

MIRIAM A. BYRNE

2000-01-01

92

Assessing tritium contamination on three surfaces  

Microsoft Academic Search

The performance of the wipe test using filter papers or cotton swabs was examined in order to determine recoveries of contamination on selected surfaces by low energy, ? emitting radioisotopes. Filter papers or cotton swabs were saturated with Scintiverse BD, Ultima Gold, Contrad 70, dish soap, methanol, ethyl acetate, or maintained dry. Wipes were taken from Formica, stainless steel or

Charles R Santerre; Jerry L Campbell; Peter C Farina; Lowell A Muse

1995-01-01

93

An Exometabolomics Approach to Monitoring Microbial Contamination in Microalgal Fermentation Processes by Using Metabolic Footprint Analysis?†  

PubMed Central

The early detection of microbial contamination is crucial to avoid process failure and costly delays in fermentation industries. However, traditional detection methods such as plate counting and microscopy are labor-intensive, insensitive, and time-consuming. Modern techniques that can detect microbial contamination rapidly and cost-effectively are therefore sought. In the present study, we propose gas chromatography-mass spectrometry (GC-MS)-based metabolic footprint analysis as a rapid and reliable method for the detection of microbial contamination in fermentation processes. Our metabolic footprint analysis detected statistically significant differences in metabolite profiles of axenic and contaminated batch cultures of microalgae as early as 3 h after contamination was introduced, while classical detection methods could detect contamination only after 24 h. The data were analyzed by discriminant function analysis and were validated by leave-one-out cross-validation. We obtained a 97% success rate in correctly classifying samples coming from contaminated or axenic cultures. Therefore, metabolic footprint analysis combined with discriminant function analysis presents a rapid and cost-effective approach to monitor microbial contamination in industrial fermentation processes.

Sue, Tiffany; Obolonkin, Victor; Griffiths, Hywel; Villas-Boas, Silas Granato

2011-01-01

94

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

95

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

96

Microbial contamination of contact lens cases in the west of Scotland  

Microsoft Academic Search

A cross-sectional study of 178 asymptomatic contact lens wearers attending 10 contact lens practices in the west of Scotland was conducted over a 4 month period. The aims of the study were to identify specific microbial contaminants in lens cases, to determine the rate of contamination of such containers and to assess the value of the steps involved in different

P Devonshire; F A Munro; C Abernethy; B J Clark

1993-01-01

97

An Analysis of the Factors for Microbial Contamination Risk for Pork at Slaughterhouses in Korea Using the Logit Model  

Microsoft Academic Search

To assess the effect of slaughtering practices on the probability of microbial contamination at slaughterhouses in Korea, 840 samples from 8 slaughterhouses were collected and 50 factors observed for 2 yr. Target microorganisms were Salmonella spp. and Listereia monocytogenes and 20 contaminated samples were found. Twenty-one out of 50 factors were identified as possible sources of microbial contamination. To narrow

Yun-Ji Kim; Yanghoon Song

2009-01-01

98

Effect of Surface Contamination on Solid Phase Welding: An Overview.  

National Technical Information Service (NTIS)

Surface contaminants hinder solid phase welding by not allowing metallic surfaces to be brought sufficiently close together that short range interatomic attractive forces operate. The effect of surface contamination on solid phase welding is worse than im...

J. L. Jellison

1978-01-01

99

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

SciTech Connect

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

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

1992-01-01

100

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

SciTech Connect

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

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

1992-12-31

101

DETECTION OF FECAL/INGESTA CONTAMINANTS ON POULTRY PROCESSING EQUIPMENT SURFACES BY VISIBLE AND NEAR-INFRARED REFLECTANCE SPECTROSCOPY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Visible and near-infrared (NIR) spectra and samples for laboratory microbial analysis were acquired of fecal contaminants, ingesta contaminants, and bare processing equipment surfaces (rubber and stainless steel) in a commercial poultry processing plant. Spectra were analyzed in the visible region ...

102

Physical and chemical factors affecting microbial biomass and activity in contaminated subsurface riverine sediments.  

PubMed

Over 80 years of direct discharge of industrial effluents into the Mahoning River, located in northeastern Ohio, USA, has led to the accumulation of a wide variety of pollutants within its sediments. This study examined the physical and chemical parameters, including lipophilic pollutants, affecting microbial activity and biomass in subsurface (10-40 cm horizon) sediments. Microbial biomass was higher in anthropogenically contaminated sediments, and step-wise linear regression showed that approximately 82% of the variation in microbial biomass could be explained by total hexane extractable hydrocarbons, sediment particle size, and water content. There was no correlation between microbial activity and biomass. Independent variables influencing anaerobic activity were temperature and water holding capacity. The results of this study indicate that freshwater, sedimentary anaerobic microbial communities respond to a range of environmental parameters, many of which influence subsurface river sediments, and that lipophilic pollutants, when present, can cause increases in total microbial biomass. PMID:16699563

Mosher, Jennifer J; Findlay, Robert H; Johnston, Carl G

2006-05-01

103

Formation of contaminant droplets on surfaces  

NASA Astrophysics Data System (ADS)

The effects of molecular film contamination on optical systems depend strongly on the film uniformity and thickness. Molecular films of uniform thickness are responsible for light transmission losses through absorption. For example, a partially darkened film of dioctyl phthalate 100 Å thick may cause losses of about 2% in the visible spectrum. However, Ternet, et al, Villahermosa, et al, and others, have shown that scattering from droplets or "puddles" can cause transmission losses of 30%. In this paper, we examine properties of the contaminant and surface that drive the formation of smooth films and droplets. It is shown that surfaces play a strong, and sometimes dominant role in controlling film or droplet formation. DC 704, a high purity, siloxane liquid, is shown to assume both droplet and smooth film character depending on the surface.

Luey, Kenneth T.; Coleman, Dianne J.

2006-09-01

104

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

2012-04-04

105

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.

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

2007-01-01

106

Microbial Biomass and Activity in Lead-Contaminated Soil  

PubMed Central

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

Konopka, A.; Zakharova, T.; Bischoff, M.; Oliver, L.; Nakatsu, C.; Turco, R. F.

1999-01-01

107

Biodegradation and surfactant-mediated biodegradation of diesel fuel by 218 microbial consortia are not correlated to cell surface hydrophobicity  

Microsoft Academic Search

In this study, we elucidated the role of cell surface hydrophobicity (microbial adhesion to hydrocarbons method, MATH) and\\u000a the effect of anionic rhamnolipids and nonionic Triton X-100 surfactants on biodegradation of diesel fuel employing 218 microbial\\u000a consortia isolated from petroleum-contaminated soils. Applied enrichment procedure with floating diesel fuel as a sole carbon\\u000a source in liquid cultures resulted in consortia of

Miko?aj Owsianiak; Alicja Szulc; ?ukasz Chrzanowski; Pawe? Cyplik; Mariusz Bogacki; Agnieszka K. Olejnik-Schmidt; Hermann J. Heipieper

2009-01-01

108

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

NASA Astrophysics Data System (ADS)

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

Thompson, I.; Lear, G.

2006-05-01

109

Efficacy of gamma irradiation for protection against postharvest insect damage and microbial contamination of adlay  

Microsoft Academic Search

This study examines the protective effects of gamma irradiation against postharvest insect damage and microbial contamination and its effect on the nutritive value of adlay (Coix lacryma-jobi L.). Adlay was treated with doses of 0–20kGy gamma irradiation and subsequently stored at ambient temperature. The number of insects, microbial quality and chemical properties of irradiated and non-irradiated adlay were evaluated immediately

Hsiao-Wei Wen; Hsiao-Ping Chung; Ya-Ting Wang; Po-Chow Hsieh; I-Hsin Lin; Fong-In Chou

2008-01-01

110

Microbial CO2 fixation potential in a tar-oil-contaminated porous aquifer.  

PubMed

CO(2) fixation is one of the most important processes on the Earth's surface, but our current understanding of the occurrence and importance of chemolithoautotrophy in the terrestrial subsurface is poor. Groundwater ecosystems, especially at organically polluted sites, have all the requirements for autotrophic growth processes, and CO(2) fixation is thus suggested to contribute significantly to carbon flux in these environments. We explored the potential for autotrophic CO(2) fixation in microbial communities of a petroleum hydrocarbon-contaminated aquifer by detection of functional marker genes (cbbL, cbbM), encoding different forms of the key enzyme RubisCO of the Calvin-Benson-Bassham cycle. Quantification of (red-like) cbbL genes revealed highest numbers at the upper fringe of the contaminant plume and the capillary fringe where reduced sulphur and iron species are regularly oxidized in the course of groundwater table changes. Functional gene sequences retrieved from this area were most closely related to sequences of different thiobacilli. Moreover, several cultures could be enriched from fresh aquifer material, all of which are able to grow under chemolithoautotrophic conditions. A novel, nitrate-reducing, thiosulfate-oxidizing bacterial strain, recently described as Thiobacillus thiophilus D24TN(T) sp. nov., was shown to carry and transcribe RubisCO large-subunit genes of form I and II. Enzyme tests proved the actual activity of RubisCO in this strain. PMID:22416961

Kellermann, Claudia; Selesi, Draženka; Lee, Natuschka; Hügler, Michael; Esperschütz, Jürgen; Hartmann, Anton; Griebler, Christian

2012-04-04

111

Ecology of Microbial Saprophytes and Pathogens in Tissue Culture and Field-Grown Plants: Reasons for Contamination Problems In Vitro  

Microsoft Academic Search

This review compares published surveys of microbial populations in plant tissue and cell cultures with the microbial saprophytes and pathogens found on field grown plants and microbial populations in the laboratory environment. From this comparison and the measured reduction in contamination after improvements in working practices in the laboratory, conclusions can be drawn about the importance of the explant and

Carlo Leifert; Cindy E. Morris; Will M. Waites

1994-01-01

112

Improved Methods for the Rapid Detection of Microbial Contaminants.  

National Technical Information Service (NTIS)

The IDT FIAX system has been demonstrated to be useful in the detection of various serum constituents by employing a solid-phase immunofluorescence technique. This project attempted to extend the use of this system to the detection of microbial contaminan...

R. Wang

1978-01-01

113

Microbial contamination of two urban sandstone aquifers in the UK  

Microsoft Academic Search

Development of urban groundwater has historically been constrained by concerns about its quality. Rising urban water tables and overabstraction from rural aquifers in the UK have led to a renewed interest in urban groundwater, particularly the possibility of finding water of acceptable quality at depth. This study assessed the microbial quality of groundwater collected from depth-specific intervals over a 15-month

Karen L. Powell; Richard G. Taylor; Aidan A. Cronin; Mike H. Barrett; Steve Pedley; Jane Sellwood; Sam A. Trowsdale; David N. Lerner

2003-01-01

114

Spatial and Temporal Modeling of Microbial Contaminants on Grazing Farmlands  

Microsoft Academic Search

the recreational use of freshwater (e.g., swimming, wa- terskiing, and windsurfing) and potential sources of wa- This paper introduces an integrated spatial and temporal modeling ter for potable treatment. system developed mathematically for assessing microbial contami- nants on animal-grazed farmlands. The model uses fecal coliform, Stainer et al. (1979) demonstrated that the main path- specifically Escherichia coli, as an indicator

Yong Q. Tian; Peng Gong; John D. Radke; James Scarborough

2002-01-01

115

Microbial contamination of alluvial gravel aquifers by septic tank effluent  

Microsoft Academic Search

The effects of two methods of septic tank effluent disposal on the microbial quality of alluvial gravel aquifers were investigated at an experimental site in the Canterbury Plains, New Zealand. The movement of faecal coliform bacteria 9 m from a 5.5 m deep soakage pit into an unconfined aquifer, and 42 m from an 18 m deep injection bore into

L. W. Sinton

1986-01-01

116

Contemporary strategies in combating microbial contamination in food chain  

Microsoft Academic Search

The objective of this review has been to disclose collected information on benefits and risks of selected “less-than – sterilizing” processes applied to control microbial hazards in food that was meticulously collected and critically reviewed during five years of EU Sixth framework project “Pathogen Combat”. The target organisms of the project, and thus of this review, too, were Listeria monocytogenes,

Andreja Rajkovic; Nada Smigic; Frank Devlieghere

2010-01-01

117

Research on the degradation of petroleum hydrocarbons on the effect of microbial activity in oil-contaminated sites  

Microsoft Academic Search

Microbe is the principal part of microbial biodegradation of soil petroleum hydrocarbons, so how to adjust the environmental conditions of the contaminated site and enhance its activity is the key to improving the efficiency of oil degradation. By collecting the original oil-contaminated soil taken in an oil deposit in Northeast and measuring soil microbial activity and indicators of environmental factors,

Jianchao Han; Yuesuo Yang

2011-01-01

118

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

Microsoft Academic Search

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

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

2006-01-01

119

Microbial contamination and purification of bivalve shellfish: Crucial aspects in monitoring and future perspectives – A mini-review  

Microsoft Academic Search

Shellfish are a nutritious food source whose consumption and commercial value has risen dramatically worldwide. Although bivalve’s consumption can contribute to a healthy diet, some can cause foodborne illnesses. Microbial contamination is chronic and pervasive in harvesting areas and may be passed on to the consumers. Current food safety programs intend to protect consumers. Nevertheless, bivalve’s microbial contamination is underestimated

J. Oliveira; A. Cunha; F. Castilho; J. L. Romalde; M. J. Pereira

2011-01-01

120

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

121

Characterizing public health and microbial risks due to water contaminants  

EPA Science Inventory

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

122

[Spatial variation of microbial properties in a creosote-contaminated soil].  

PubMed

By the methods of geostatistics, this paper studied the spatial variation of microbial biomass, microbial community structure and microbial activity in a creosote-contaminated soil. The microbial biomass was indicated by the total amount of 26 examined phospholipid fatty acids (totPLFA), the microbial community structure was characterized by the first two principal components (PC1 and PC2) of the PLFA patterns through subjecting the PLFAs to principal component analysis, and the total amount of CO2-C respired (C(re)) during incubation was used to describe the soil microbial activity. The results showed that most of the variables exhibited various degrees of spatial autocorrelation, and spherical models with nugget could fit their semivariograms. The estimated spatial dependence distances of the variables varied from 2.50 to 16.60 m. The PLFA PC1, totPLFA and C(re) displayed relatively high spatial dependences, their relative structural variance, i.e., the proportion of total variance that can be attributed to the spatial autocorrelation, being 82.3%, 79.6% and 64.7%, respectively, while PLFA PC2 was not spatially autocorrelated. The kriged maps showed that there were several hot spots with relatively high microbial biomass and high microbial activity located in the study site. Gram- negative bacteria characterized by PLFAs 16:1omega7t, cyl7:0, 18:1omega7 and cyl9:0 were the dominant community in these hot spots. The concentration and spatial distribution of polycyclic aromatic hydrocarbons as the main contaminants in the soil could be one of the important factors affecting the spatial variation of soil microbial properties. PMID:16110676

Yang, Xiuhong; Li, Shiyu; Bengtsson, Göran; Törneman, Niklas

2005-05-01

123

Microbial contamination of medications used to treat glaucoma  

Microsoft Academic Search

AIMS--A study was conducted to estimate the frequency of contamination of topical antiglaucoma medications used by asymptomatic patients. METHODS--The drops and the bottle tips of 194 in use topical medications and the conjunctiva from 109 treated glaucoma patients were cultured. RESULTS--Bacteria were recovered from 55 (28%) medications. The bottle tip was more frequently contaminated than the drops (p = 0.008).

O Geyer; E J Bottone; S M Podos; R A Schumer; P A Asbell

1995-01-01

124

Portable spotter for fluorescent contaminants on surfaces  

DOEpatents

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

Schuresko, Daniel D. (Oak Ridge, TN)

1980-01-01

125

Diversity responses of rumen microbial communities to Fusarium-contaminated feed, evaluated with rumen simulating technology.  

PubMed

The mycotoxin-producing fungus Fusarium culmorum causes major feed spoilages in agricultural livestock, but effects of F. culmorum-contaminated feed on the structural diversity of the rumen-inhabiting microbial community are not understood. Avoiding animal experiments, this study was conducted with the rumen simulating technique (Rusitec). Small subunit (SSU) rRNA gene copy numbers of bacteria and archaea, determined by quantitative polymerase chain reaction (PCR), indicated no differences between contaminated and non-contaminated digested feed, but fungal copy numbers, not attributable to F. culmorum itself, were elevated approximately fourfold in the contaminated feed, with 2.3 x 10(9) g(-1) dry weight. Single-strand conformation polymorphism profiles of PCR-amplified partial SSU rRNA genes revealed a single but clear difference between contaminated and non-contaminated feed in profiles encompassing the phylogenetic clusters of Fibrobacteriales and Clostridiales. Minor quantitative differences were also seen in profiles of archaea and fungi. Positive correlations were found between fungal rRNA gene copy numbers and the degradability of different nutrients, but there was no correlation with degradation rates of the major mycotoxin contaminant deoxynivalenol. Thus, the diversity responses of the microbial community to F. culmorum-contaminated feed were caused by a fungus-induced, altered feed quality rather than by direct mycotoxicity. PMID:18177368

Strobel, Egbert; Seeling, Karen; Tebbe, Christoph C

2007-12-19

126

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.

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

2012-01-01

127

Microbial rhodopsins on leaf surfaces of terrestrial plants  

PubMed Central

Summary The above-ground surfaces of terrestrial plants, the phyllosphere, comprise the main interface between the terrestrial biosphere and solar radiation. It is estimated to host up to 1026 microbial cells that may intercept part of the photon flux impinging on the leaves. Based on 454-pyrosequencing-generated metagenome data, we report on the existence of diverse microbial rhodopsins in five distinct phyllospheres from tamarisk (Tamarix nilotica), soybean (Glycine max), Arabidopsis (Arabidopsis thaliana), clover (Trifolium repens) and rice (Oryza sativa). Our findings, for the first time describing microbial rhodopsins from non-aquatic habitats, point towards the potential coexistence of microbial rhodopsin-based phototrophy and plant chlorophyll-based photosynthesis, with the different pigments absorbing non-overlapping fractions of the light spectrum.

Atamna-Ismaeel, Nof; Finkel, Omri M.; Glaser, Fabian; Sharon, Itai; Schneider, Ron; Post, Anton F.; Spudich, John L.; von Mering, Christian; Vorholt, Julia A.; Iluz, David; Beja, Oded; Belkin, Shimshon

2013-01-01

128

Microbial Contamination of Seven Major Weaning Foods in Nigeria  

PubMed Central

Five million children aged less than five years die annually due to diarrhoea. The aim of the study was to identify some possible contributing factors for persistent diarrhoea. Seven weaning foods, including a locally-made food, were evaluated by estimating the microbial load using the most probable number method and aflatoxin levels (AFM1, AFG1, AFG2, and AFB2) by immunoaffinity column extraction and high-performance liquid chromatography (HPLC) with detection of fluorescence. The results showed that the locally-made weaning food had the highest microbial count (2,000 cfu/g) and faecal streptococcal count (25 cfu/g). Moulds isolated were mainly Aspergillus niger, A. flavus, A. glaucus, Cladosporium sp., and Penicillium sp. The home-made weaning food recorded the highest fungal count (6,500 cfu/g). AFM1 of the weaning foods was 4.6-530 ng/mL. One weaning food had AFB1 level of 4,806 ng/g. Aflatoxin metabolites, apart from AFM1 and AFB1 present in the weaning foods, were AFG1 and AFG2. There were low microbial counts in commercial weaning foods but had high levels of aflatoxins (AFM1, AFG1, AFG2, AFB1, and AFB2). Growth and development of the infant is rapid, and it is, thus, possible that exposure to aflatoxins in weaning foods might have significant health effects.

Ibeh, I. Nnanna

2011-01-01

129

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...

130

Evaluation of the Effect of Arsenic Contamination on Selected Soil Enzyme Activities and Microbial Diversity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Environmental impact of different contaminants which enter the soil can alter the diversity of the soil microflora thus disrupting their ability to maintain soil quality and health. Due to the vital role played by the diverse soil microbes in soil, the measurement of the soil microbial diversity has...

131

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

132

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. Understanding the geophysical signatures of microbial activity in the environment has resulted in the development of a new sub-discipline in geophysics called ``biogeophysics''. This review focuses primarily on literature pertaining to biogeophysical signatures of sites contaminated by light non-aqueous phase liquids (LNAPL),

Estella A. Atekwana; Eliot A. Atekwana

2010-01-01

133

Bioaerosol Contamination of Ambient Air as the Result of Opening Envelopes Containing Microbial Materials  

Microsoft Academic Search

Mailing envelopes containing pathogenic spores of bacillus anthraxes, which have recently been used by terrorists to infect humans, calls for a new investigation to identify a level of possible contamination of ambient air as a result of the opening of such envelopes. Here we show that opening an envelope and unfolding a letter aerosolize microbial particles located inside and create

Igor E. Agranovski; Oleg V. Pyankov; Igor S. Altman

2005-01-01

134

Microbial indicators of contamination of water and sediments by warfare agents in Baltic Sea dump sites  

Microsoft Academic Search

Our research revealed changes in the composition of the Baltic Sea microbial populations, namely, an increase in numbers of the physiological group of microorganisms that develop owing to organic compounds contaminating chemical weapon dump sites. We found that mustard gas hydrolysis products (MGHPs) - tolerant microorganisms were predominant in nearbottom water in many stations in the Baltic Sea dumping areas.

Yulia Polyak; Nadezda Medvedeva; Tatyana Zaytseva

2008-01-01

135

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

SciTech Connect

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 landfill. The information will be used to evaluate natural attenuation of the associated CE plume. Two groundwater-monitoring wells were tested.

Brigmon, R.L.

2002-05-17

136

Alkane biodegradation by a microbial community from contaminated sediments in Patagonia, Argentina  

Microsoft Academic Search

Biodegradation of a mix of normal alkanes (decane, dodecane, tetradecane, hexadecane, octadecane and eicosane) was studied in batch cultures after inoculating with microbial communities from pristine and hydrocarbon contaminated sediments. Analysis showed that the community from polluted sediments reduced the concentrations of all alkanes to < 5 mg l?1 after a 240-h incubation period (< 5% initial concentration), while the

Nelda L. Olivera; José L. Esteves; Marta G. Commendatore

1997-01-01

137

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

138

Microbial cellulose decomposition in soils from a rifle range contaminated with heavy metals  

Microsoft Academic Search

The objective of this study was to assess the effects of heavy metals on microbial decomposition of cellulose in heavy metal-contaminated soils using a cotton strip assay. The assay is a measure of the potential of soil microorganisms to decompose the plant polymer, cellulose. Cellulolytic activity in soil was assessed by determining the reduction in tensile strength of the buried

I Chew; J. P Obbard; R. R Stanforth

2001-01-01

139

A shallow BTEX and MTBE contaminated aquifer supports a diverse microbial community.  

PubMed

Microbial communities in subsurface environments are poorly characterized and the impacts of anthropogenic contamination on their structure and function have not been adequately addressed. The release of contaminant(s) to a previously unexposed environment is often hypothesized to decrease the diversity of the affected community. We characterized the structure of microbial communities along a gradient of benzene, toluene, ethylbenzene, and xylene (BTEX) and methyl-tert-butyl-ether (MTBE) contamination, resulting from a petroleum spill, within a shallow sandy aquifer at Vandenberg Air Force Base (VAFB) in Lompoc, CA. Differences in microbial community composition along the contaminant plume were assessed via a combinatorial approach utilizing denaturing gradient gel electrophoresis (DGGE), cloning and sequencing, intergenic transcribed spacer analysis (ITS), and comparative phylogenetic analysis of partial 16S rDNA sequences. Substantial bacterial sequence diversity, similar levels of species richness, and similar phylo-groups (including the Cytophaga-Flavobacterium-Bacteroidetes group and numerous members of the alpha-, beta-, gamma-, delta-, and epsilon-groups of the proteobacteria) were observed in both uncontaminated and contaminated regions of the aquifer. High-resolution measures (ITS fingerprinting and phylogenetic inference) readily separated communities impacted by the original petroleum spill (in source zone) from those in other parts of the aquifer and indicated that communities exposed to MTBE only were similar to communities in uncontaminated regions. Collectively, these data suggest that petroleum contamination alters microbial community structure at the species and subspecies level. Further study is required to determine whether these changes have an impact on the functioning of this subsurface ecosystem. PMID:15696392

Feris, K P; Hristova, K; Gebreyesus, B; Mackay, D; Scow, K M

2004-10-28

140

Impact of long-term diesel contamination on soil microbial community structure.  

PubMed

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

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

2012-11-09

141

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

2012-10-14

142

[Microbial contamination of the air in the wood-processing industry].  

PubMed

Studies of the microbial dissemination levels in wood-processing and furniture-producing plants facilitated establishing of their increased bacterial and fungus contamination. Possible sensibilization of these factors necessitated hygienic and sanitary measures (ventilation, hermetization of the equipment, aspiration, dust-cleaning, bactericidal light devices provision) which lowered the bacterial contamination level by 40-60%. The high morbidity rate caused by upper respiratory diseases (56.1%) conditioned further elaboration of inhalation techniques as part of therapeutic and preventive measures. The techniques should be developed with due account of the bacterial and fungus contamination of industrial dusts and possible human sensibilization to these factors. PMID:1839001

Petretski?, V V; Kunel'skaia, V Ia; Petretski?, N V

1991-01-01

143

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

144

Microbial contamination of cell cultures: A 2 years study  

Microsoft Academic Search

Cell line contamination is a major drawback of main cell banks of the world and it has cost of losing important biological products or valuable research. The causative agents are different chemicals, invertebrates, bacteria, fungi, parasites, viral species and even other cell lines. In this retrospective study, cell lines from various species such as human, fish, insect, animals either offered

A. Mirjalili; E. Parmoor; S. Moradi Bidhendi; B. Sarkari

2005-01-01

145

Application of atomic force microscopy to microbial surfaces: from reconstituted cell surface layers to living cells.  

PubMed

The application of atomic force microscopy (AFM) to probe the ultrastructure and physical properties of microbial cell surfaces is reviewed. The unique capabilities of AFM can be summarized as follows: imaging surface topography with (sub)nanometer lateral resolution; examining biological specimens under physiological conditions; measuring local properties and interaction forces. AFM is being used increasingly for: (i) visualizing the surface ultrastructure of microbial cell surface layers, including bacterial S-layers, purple membranes, porin OmpF crystals and fungal rodlet layers; (ii) monitoring conformational changes of individual membrane proteins; (iii) examining the morphology of bacterial biofilms, (iv) revealing the nanoscale structure of living microbial cells, including fungi, yeasts and bacteria, (v) mapping interaction forces at microbial surfaces, such as van der Waals and electrostatic forces, solvation forces, and steric/bridging forces; and (vi) probing the local mechanical properties of cell surface layers and of single cells. PMID:10936459

Dufrêne, Y F

2001-02-01

146

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

PubMed Central

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

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

2008-01-01

147

Microbial Biogeography of Public Restroom Surfaces  

Microsoft Academic Search

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

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

2011-01-01

148

Early warning system for detection of microbial contamination of source waters  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

149

On-farm sources of microbial contamination of persimmon fruit in Japan.  

PubMed

Potential sources of microbial contamination for persimmon fruit during growing and harvesting in the 2005 season were investigated to provide a baseline to design the good agricultural practices program for persimmons in Japan. Microbial counts in the peel of persimmon fruit during production season were close to or below 2.4 log CFU/g for bacteria and 3.0 log CFU/g for fungi but were above these values on harvested fruit. The counts in the flesh were below the detection level with all fruit. Bacteria and molds isolated from peel and flesh of persimmons during growing were phytopathogenic and soilborne organisms such as bacteria genera Enterobacter and Bacillus and mold genera Fusarium and Cladosporium, which were found in soil, weeds, agricultural water, and pesticide solution throughout the production season. The agricultural water was one of the most important potential preharvest sources, because Escherichia coli O157:H7 was identified from agricultural water in May, and Salmonella was detected in agricultural water, pesticide solution containing the agricultural water for the mixture, and soil after application of the pesticide solution in June. Neither of the two pathogenic bacteria was detected in any of the fruit samples. Microbial counts and diversity in the peel of persimmons at harvest increased after contact with plastic harvest basket and container, which could be sources of contamination during harvesting. Therefore, monitoring and management on-farm should focus on agricultural water and harvest equipment as important control points to reduce microbial contamination on persimmons. PMID:18236662

Izumi, Hidemi; Tsukada, Yumi; Poubol, Jutatip; Hisa, Kazuo

2008-01-01

150

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

151

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

152

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

Microsoft Academic Search

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

Å. Frostegård; A. Tunlid; E. Bååth

1996-01-01

153

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

PubMed

Phytoremediation, an approach that uses plants to remediate contaminated soil through degradation, stabilization or accumulation, may provide an efficient solution to some mercury contamination problems. This paper presents growth chamber experiments that 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 southern Poland. The uptake and distribution of mercury by these plants were investigated, and the growth and vitality of the plants through a part of one vegetative cycle were assessed. The highest concentrations of mercury were found at the roots, but translocation to the aerial part also occurred. Most of the plant species tested displayed good growth on mercury contaminated soil and sustained a rich microbial population in the rhizosphere. The microbial populations of root-free soil and rhizosphere soil from all species were also examined. An inverse correlation between the number of sulfur amino acid decomposing bacteria and root mercury content was observed. These results indicate the potential for using some species of plants to treat mercury contaminated soil through stabilization rather than extraction. The present investigation proposes a practical cost-effective temporary solution for phytostabilization of soil with moderate mercury contamination as well as the basis for plant selection. PMID:17492484

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

2007-05-11

154

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

PubMed

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

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

2013-07-09

155

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.

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

1978-01-01

156

Use of toll-like receptor assays to detect and identify microbial contaminants in biological products.  

PubMed

Toll-like receptor (TLR)-expressing cells, for the first time, detected and identified a microbial contaminant in a product made in Escherichia coli using an old manufacturing process. It was suspected of having a microbial contaminant(s) because, although it tested negative by standard pyrogen assays, it was associated with adverse events in early clinical trials. The assay readout is the induction of NF-kappaB and/or cytokines in response to TLR activation. Four coded samples, labeled A to D, including a sample prepared by the older manufacturing process, were submitted. The cell lines were activated only by samples B and D. Sample D stimulated only Mono-Mac 6 and HEK-human TLR4 (hTLR4) cells and was later identified as lipopolysaccharide. Except for TLR3 cells, sample B stimulated cells bearing the different TLRs (TLRs 2, 4, 5, 7, 8, and 9) and nontransfected HEK293 cells. These data suggested that flagellin was the microbial contaminant, since TLR5, the receptor for flagellin, is known to be expressed constitutively on HEK293 cells. Moreover, purified flagellin from Salmonella enterica serovar Typhimurium behaved like sample B, stimulating HEK293 and HEK-hTLR5 cells but not HEK-hTLR3 cells, and this stimulation by flagellin and sample B was blocked by an anti-hTLR5 neutralizing antibody. Western blots showed bands positive for flagellin and sample B with the molecular sizes expected for the flagellins from S. Typhimurium and E. coli, respectively. Mass spectrometry data were consistent with the presence of flagellin in the manufacturer's sample B. Taken together, these data indicate that the microbial contaminant in sample B was flagellin and may have been associated with adverse events when the recombinant product was administered. PMID:19726599

Huang, Li-Yun; Dumontelle, James L; Zolodz, Melissa; Deora, Aparna; Mozier, Ned M; Golding, Basil

2009-09-02

157

Analysis of surface contaminants on beryllium and aluminum windows  

SciTech Connect

An effort has been made to document the types of contamination which form on beryllium window surfaces due to interaction with a synchrotron radiation beam. Beryllium windows contaminated in a variety of ways (exposure to water and air) exhibited surface powders, gels, crystals and liquid droplets. These contaminants were analyzed by electron diffraction, electron energy loss spectroscopy, energy dispersive x-ray spectroscopy and wet chemical methods. Materials found on window surfaces include beryllium oxide, amorphous carbon, cuprous oxide, metallic copper and nitric acid. Aluminum window surface contaminants were also examined.

Gmur, N.F.

1987-06-01

158

Microbial Community Structure and Function at an Aquifer Contaminated with Landfill Leachate (Norman,OK)  

NASA Astrophysics Data System (ADS)

Geochemical research at an aquifer contaminated with landfill leachate (Norman, OK) has shown that contaminated areas have significant increases in the concentration of dissolved organic carbon (DOC) and persistent anaerobic conditions as compared to uncontaminated areas. As a result, sulfate is depleted in the center of the contaminant plume with concomitant increases in Fe(II) and methane. These observations have been used to infer the dominant biogeochemical processes in this ecosystem which include Fe reduction, sulfate reduction, and methanogenesis. Because each of these processes is microbially-mediated, the goal of this study was to use a combination of culture-based and molecular methods to determine the composition and diversity of the microbial community in the contaminant plume. Groundwater and sediment samples were collected along the flow path of contamination in June 2005. We used most probable number (MPN) analyses to determine the abundances of key functional groups of bacteria including methanogens, sulfate-reducers (SRB), and iron-reducers (FeRB). Quantitative PCR (qPCR) was performed to determine abundances of functional genes of the dissimilatory sulfite reductase (dsr) and methyl coenzyme M-reductase (mcr) genes and the 16 rRNA genes targeting Geobacter spp. Results from the MPN analyses confirmed the presence of a relatively abundant and diverse anaerobic community in the groundwater at the landfill (e.g. 102 SRB, FeRB ml-1. In general, with increasing distance from the source of contamination, abundances of FeRB, SRB, and methanogens decreased to < 101 cells ml-1 groundwater and < 102 cells g soil. In fact, most of these groups were undetectable throughout much of the sampling transect, particularly in the groundwater. For example, methanogens were largely absent despite the presence of high concentrations of methane. In contrast to these estimates obtained with MPN analyses, the results of qPCR indicated that there were measurable, and many times substantial numbers of mcr and dsr genes and Geobacter spp. in the vast majority of the samples. This indicates that qPCR may be a more sensitive screening tool for quantifying abundances of functional groups. Collectively, these results suggest that the lack of an abundant microbial community in some parts of the contaminant plume may limit biogeochemical activity, even in the presence of adequate electron donors and/or acceptors. Furthermore, the complex relationship between the composition of the microbial community and the geochemistry of this aquifer indicate that obtaining both geochemical and microbial information may be necessary to adequately understand the controls on subsurface biogeochemical processes.

Weiss, J. V.; Voytek, M. A.; Lowit, M. B.; Cozzarelli, I. M.; Kirshtein, J. D.

2006-05-01

159

Functional gene array-based analysis of microbial community structure in groundwater with gradient of contaminant levels  

SciTech Connect

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

Wu, Liyou [University of Oklahoma, Norman; Van Nostrand, Joy [University of Oklahoma, Norman; Schadt, Christopher Warren [ORNL; Watson, David B [ORNL; Jardine, Philip M [ORNL; Palumbo, Anthony Vito [ORNL; Hazen, Terry [Lawrence Berkeley National Laboratory (LBNL); Zhou, Jizhong [University of Oklahoma, Norman

2009-04-01

160

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

PubMed

To understand how contaminants affect microbial community diversity, heterogeneity, and functional structure, six groundwater monitoring wells from the Field Research Center of the U.S. Department of Energy Environmental Remediation Science Program (ERSP; Oak Ridge, TN), with a wide range of pH, titrate, and heavy metal contamination were investigated. DNA from the groundwater community was analyzed with a functional gene array containing 2006 probes to detect genes involved in metal resistance, sulfate reduction, organic contaminant degradation, and carbon and nitrogen cycling. Microbial diversity decreased in relation to the contamination levels of the wells. Highly contaminated wells had lower gene diversity but greater signal intensity than the pristine well. The microbial composition was heterogeneous, with 17-70% overlap between differentwells. Metal-resistant and metal-reducing microorganisms were detected in both contaminated and pristine wells, suggesting the potential for successful bioremediation of metal-contaminated groundwaters. In addition, results of Mantel tests and canonical correspondence analysis indicate that nitrate, sulfate, pH, uranium, and technetium have a significant (p < 0.05) effect on microbial community structure. This study provides an overall picture of microbial community structure in contaminated environments with functional gene arrays by showing that diversity and heterogeneity can vary greatly in relation to contamination. PMID:19544850

Waldron, Patricia J; Wu, Liyou; Van Nostrand, Joy D; Schadt, Chris W; He, Zhili; Watson, David B; Jardine, Philip M; Palumbo, Anthony V; Hazen, Terry C; Zhou, Jizhong

2009-05-15

161

Microbial Contamination of In-Use Ocular Medications  

Microsoft Academic Search

\\\\s=b\\\\Two hundred twenty in-use medica- tions from 101 patients with nonmicro- bial ocular surface disease were studied by culturing the bottle caps, a drop pro- duced by simple inversion, and the interi-

Oliver D. Schein; Patricia L. Hibberd; Tomy Starck; Ann S. Baker; Kenneth R. Kenyon

2010-01-01

162

Microbial biomass and activities associated with subsurface environments contaminated with chlorinated hydrocarbons  

SciTech Connect

Soil microcosms and enrichment cultures from subsurface sediments and ground waters contaminated with trichloroethylene (TCE) were examined. Total lipids, (1-C{sub 14})acetate incorporation into lipids, and (Me{sup 3}H)thymidine incorporation into DNA were determined in these subsurface environments. In heavily TCE-contaminated zones radioisotopes were not incorporated into lipids or DNA. Radioisotope incorporation occurred in sediments both above and below the TCE plume. Phospholipid fatty acids (PLFA) were not detected, i.e., < 0.5 pmol/L in heavily contaminated groundwater samples. In less contaminated waters, extracted PLFA concentrations were greater than 100 pmol/L and microbial isolates were readily obtained. Degradation of 30-100 mg/L TCE was observed when sediments were amended with a variety of energy sources. Microorganisms in these subsurface sediments have adapted to degrade TCE at concentrations greater than 50 mg/L. 34 refs., 4 figs., 4 tabs.

Phelps, T.J.; Ringelberg, D.; Hedrick, D.; Davis, J.; Fliermans, C.B. (Univ. of Tennessee, Knoxville (USA))

1988-01-01

163

Microbially Supported Phytoremediation of Heavy Metal Contaminated Soils: Strategies and Applications.  

PubMed

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

Phieler, René; Voit, Annekatrin; Kothe, Erika

2013-05-30

164

Genotypic and phenotypic responses of a riverine microbial community to polycyclic aromatic hydrocarbon contamination  

SciTech Connect

The phenotypic and genotypic adaptation of a freshwater sedimentary microbial community to elevated levels of polycyclic aromatic hydrocarbons (PAHs) was determined by using an integrated biomolecular approach. Central to the approach was the use of phospholipid fatty acid (PLFA) profiles to characterize the microbial community structure and nucleic acid analysis to quantify the frequency of degradative genes. The study site was the Little Scioto River, a highly impacted, channelized riverine system located in central Ohio. This study site is a unique lotic system, with all sampling stations having similar flow and sediment characteristics both upstream and downstream from the source of contamination. These characteristics allowed for the specific analysis of PAH impact on the microbial community. PAH concentrations in impacted sediments ranged from 22 to 217 {micro}g g(dry weight) of sediment{sup {minus}1}, while PAH concentrations in ambient sediments ranged from below detection levels to 1.5 {micro}g g (dry weight) of sediment{sup {minus}1}. Total microbial biomass measured by phospholipid phosphate (PLP) analysis ranged from 95 to 345 nmol of PLP g(dry weight) of sediment{sup {minus}1}. Nucleic acid analysis showed the presence of PAH-degradative genes at all sites, although observed frequencies were typically higher at contaminated sites. Principal component analysis of PLFA profiles indicated that moderate to high PAH concentrations altered microbial community structure and that seasonal changes were comparable in magnitude to the effects of PAH pollution. These data indicate that this community responded to PAH contamination at both the phenotypic and the genotypic level.

Langworthy, D.E.; Findlay, R.H. [Miami Univ., Oxford, OH (United States). Dept. of Microbiology; Stapleton, R.D.; Sayler, G.S. [Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology

1998-09-01

165

Genotypic and Phenotypic Responses of a Riverine Microbial Community to Polycyclic Aromatic Hydrocarbon Contamination  

PubMed Central

The phenotypic and genotypic adaptation of a freshwater sedimentary microbial community to elevated (22 to 217 ?g g [dry weight] of sediment?1) levels of polycyclic aromatic hydrocarbons (PAHs) was determined by using an integrated biomolecular approach. Central to the approach was the use of phospholipid fatty acid (PLFA) profiles to characterize the microbial community structure and nucleic acid analysis to quantify the frequency of degradative genes. The study site was the Little Scioto River, a highly impacted, channelized riverine system located in central Ohio. This study site is a unique lotic system, with all sampling stations having similar flow and sediment characteristics both upstream and downstream from the source of contamination. These characteristics allowed for the specific analysis of PAH impact on the microbial community. PAH concentrations in impacted sediments ranged from 22 to 217 ?g g (dry weight) of sediment?1, while PAH concentrations in ambient sediments ranged from below detection levels to 1.5 ?g g (dry weight) of sediment?1. Total microbial biomass measured by phospholipid phosphate (PLP) analysis ranged from 95 to 345 nmol of PLP g (dry weight) of sediment?1. Nucleic acid analysis showed the presence of PAH-degradative genes at all sites, although observed frequencies were typically higher at contaminated sites. Principal component analysis of PLFA profiles indicated that moderate to high PAH concentrations altered microbial community structure and that seasonal changes were comparable in magnitude to the effects of PAH pollution. These data indicate that this community responded to PAH contamination at both the phenotypic and the genotypic level.

Langworthy, Donald E.; Stapleton, Raymond D.; Sayler, Gary S.; Findlay, Robert H.

1998-01-01

166

Bioremediation of Pb-contaminated soil based on microbially induced calcite precipitation.  

PubMed

To remediate lead (Pb)-contaminated soils, it is proposed that microbially induced calcite precipitation (MICP) would provide the best alternative to other remediation technologies. In this study, Pb bioremediation in soils was investigated using the calcite-precipitating bacterium Kocuria flava. Results indicate that the Pb is primarily associated with the carbonate fraction in bioremediated soil samples. The bioavailability of Pb in contaminated soil was reduced so that the potential stress of Pb was alleviated. This research provides insight into the geochemistry occurring in the MICP-based Pb-remediated soils, which will help in remediation decisions. PMID:22370357

Achal, Varenyam; Pan, Xiangliang; Zhang, Daoyong; Fu, Qinglong

2012-02-01

167

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

168

Microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants in lead contaminated soil  

PubMed Central

The goals of this study were to evaluate the microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants (Caesalpinia ferrea, Mimosa tenuiflora and Erythrina velutina) in lead contaminated soil from the semi-arid region of northeastern of Brazil (Belo Jardim, Pernambuco). Dilutions were prepared by adding lead contaminated soil (270 mg Kg-1) to uncontaminated soil (37 mg Pb Kg soil-1) in the proportions of 7.5%, 15%, and 30% (v:v). The increase of lead contamination in the soil negatively influenced the amount of carbon in the microbial biomass of the samples from both the dry and rainy seasons and the metabolic quotient only differed between the collection seasons in the 30% contaminated soil. The average value of the acid phosphatase activity in the dry season was 2.3 times higher than observed during the rainy season. There was no significant difference in the number of glomerospores observed between soils and periods studied. The most probable number of infective propagules was reduced for both seasons due to the excess lead in soil. The mycorrhizal colonization rate was reduced for the three plant species assayed. The inoculation with arbuscular mycorrhizal fungi benefited the growth of Erythrina velutina in lead contaminated soil.

Gattai, Graziella S.; Pereira, Sonia V.; Costa, Cynthia M. C.; Lima, Claudia E. P.; Maia, Leonor C.

2011-01-01

169

Microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants in lead contaminated soil.  

PubMed

The goals of this study were to evaluate the microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants (Caesalpinia ferrea, Mimosa tenuiflora and Erythrina velutina) in lead contaminated soil from the semi-arid region of northeastern of Brazil (Belo Jardim, Pernambuco). Dilutions were prepared by adding lead contaminated soil (270 mg Kg(-1)) to uncontaminated soil (37 mg Pb Kg soil(-1)) in the proportions of 7.5%, 15%, and 30% (v:v). The increase of lead contamination in the soil negatively influenced the amount of carbon in the microbial biomass of the samples from both the dry and rainy seasons and the metabolic quotient only differed between the collection seasons in the 30% contaminated soil. The average value of the acid phosphatase activity in the dry season was 2.3 times higher than observed during the rainy season. There was no significant difference in the number of glomerospores observed between soils and periods studied. The most probable number of infective propagules was reduced for both seasons due to the excess lead in soil. The mycorrhizal colonization rate was reduced for the three plant species assayed. The inoculation with arbuscular mycorrhizal fungi benefited the growth of Erythrina velutina in lead contaminated soil. PMID:24031701

Gattai, Graziella S; Pereira, Sônia V; Costa, Cynthia M C; Lima, Cláudia E P; Maia, Leonor C

2011-09-01

170

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

SciTech Connect

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

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

2012-01-01

171

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

172

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

Microsoft Academic Search

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

Michael J. Tesch; Walter G. Goodman

1995-01-01

173

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

174

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

Microsoft Academic Search

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

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

1998-01-01

175

Leaching and microbial treatment of a soil contaminated by sulphide ore ashes and aromatic hydrocarbons  

Microsoft Academic Search

Contaminated soil from a historical industrial site and containing sulfide ore ashes and aromatic hydrocarbons underwent sequential\\u000a leaching by 0.5 M citrate and microbial treatments. Heavy metals leaching was with the following efficiency scale: Cu (58.7%)\\u000a > Pb (55.1%) > Zn (44.5%) > Cd (42.9%) > Cr (26.4%) > Ni (17.7%) > Co (14.0%) > As (12.4%) > Fe (5.3%) >

Alessandro D’Annibale; Vanessa Leonardi; Ermanno Federici; Franco Baldi; Fulvio Zecchini; Maurizio Petruccioli

2007-01-01

176

Microbial contamination of ship fuels. [Mercaptopyridine, methylene bisthiocyanate, triazines, organoboron compounds  

Microsoft Academic Search

A laboratory evaluation has been made of water-soluble biocides which might be effective in controlling microbial contamination in water-compensated fuel storage tanks on naval ships. Higher concentrations of biocides were generally required for control of sulfate-reducing bacteria in steel drums simulating ships' tanks than in test-tube scale assays. At least tenfold higher concentrations were necessary when biocide additions were made

R. A. Neihof; D. E. Klemme; C. E. Patouillet; P. J. Hannan

1981-01-01

177

Spread of microbial contamination associated with penetrative captive bolt stunning of food animals  

Microsoft Academic Search

To determine whether penetrative stunning of animals can result in internal and\\/or external microbial contamination of meat, experimental animals (lambs) were inoculated with a marker organisms (nalidixic acid resistant Escherichia coli K12 or Pseudomonas fluorescens) into the brain through the stun wound immediately after stunning by a cartridge-operated, penetrative captive bolt pistol. After the animals were slaughtered and dressed, the

S Buncic; J McKinstry; C.-A Reid; M. H Anil

2002-01-01

178

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

2013-07-01

179

Iron-mediated microbial oxidation and abiotic reduction of organic contaminants under anoxic conditions.  

PubMed

In anoxic environments, the oxidation of organic compounds, such as BTEX fuel components, by dissimilatory Fe(III) reduction can generate reactive mineral-bound Fe(II) species, which in turn are able to reduce other classes of organic and inorganic groundwater contaminants. In this study, we designed and evaluated an anaerobic batch reactor that mimicks iron-reducing conditions to investigate the factors that favor the coupling of microbial toluene oxidation and abiotic reduction of nitroaromatic contaminants. We investigated the influence of different Fe(III)-bearing minerals and combinations thereof on the coupling of these two processes. Results from laboratory model systems show that complete oxidation of toluene to CO2 by Geobacter metallireducens in the presence of Fe(III)-bearing minerals leads to the formation of mineral-bound Fe(II) species capable of the reduction of 4-nitroacetophenone. Whereas significant microbial toluene oxidation was only observed in the presence of amorphous Fe(III) phases, reduction of nitroaromatic compounds only proceeded with Fe(II) species bound to crystalline Fe(III) oxides. Our results suggest that in anoxic soils and sediments containing amorphous and crystalline iron phases simultaneously, coupling of microbial oxidation and abiotic reduction of organic compounds may allow for concurrent natural attenuation of different contaminant classes. PMID:18075086

Tobler, Nicole B; Hofstetter, Thomas B; Straub, Kristina L; Fontana, Daniela; Schwarzenbach, René P

2007-11-15

180

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

PubMed

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

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

2011-12-13

181

Contamination effects on optical surfaces in the monolayer regime  

NASA Astrophysics Data System (ADS)

A vacuum-conditions study has been conducted for the deposition behavior of contaminant films of less-than-10-A thickness, with a view to the dependence of the deposition behavior on the contaminant and condensing surface compositions. The contaminants, representative of those encountered in space environments, were methyl phenyl siloxanes and the common plasticizer dioctyl phthalate; the condensing surfaces were specular finish Al overcoatings, diffuse finish Al overcoatings, and MgF2 specular finish overcoatings. The attractive force between the condensing surface and the contaminant molecule was a contributing factor in mass accumulation behavior.

Bartosik, L. G.; Smith, C. A.; Steinburn, M. A.; Glassford, A. P. M.

1989-10-01

182

Microbial activity and community structure of a soil after heavy metal contamination in a model forest ecosystem  

Microsoft Academic Search

We assessed the effects of chronic heavy metal (HM) contamination on soil microbial communities in a newly established forest ecosystem. We hypothesized that HM would affect community function and alter the microbial community structure over time and that the effects are more pronounced in combination with acid rain (AR). These hypotheses were tested in a model forest ecosystem consisting of

Beat Frey; Michael Stemmer; Franco Widmer; Joerg Luster; Christoph Sperisen

2006-01-01

183

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

184

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

SciTech Connect

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

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

2002-08-01

185

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

186

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

187

The evaluation of microbial contamination in platelet concentrates prepared by two different methods.  

PubMed

The microbial contamination of platelet concentrates (PCs) prepared by two different methods both with a high risk of bacterial contamination during preparation and storage were evaluated. For apheresis platelets, the concentrates were obtained using the Haemonetics MCS 3P device. For the random method, platelets were obtained by two phase centrifugation, in the Heraeus Cryofuge 8500 I device using the Kansuk 3-way bags which permit storage for five days. 1620 plateletpheresis units prepared by apheresis, and 9838 units prepared by the random method, were included in the study. Of the 11,458 PCs studied. 32 (0.27%) were false positives and 24 (0.2%) were real positives. All of the positive results occurred in platelets prepared by the random method. C. xerosis and S. epidermidis, S. hominis, Alpha-hemolytic streptococci, all flora of the skin, were isolated in the contaminated concentrates. The risk of microbial contamination of PCs, prepared both by apheresis and from whole blood, continues at a low rate although the products were collected into specific bags following rules including appropriate disinfection of the skin, correct centrifugation collection time and optimal storage conditions including temperature and agitation. These results again emphasize the importance of: obeying phlebotomy rules and hand disinfection of the person who collects the blood as well as the need for careful skin decontamination of the donor, during donation. PMID:11761274

Kocazeybek, B; Arabaci, U; Akdur, H; Sezgiç, M; Erentürk, S

2001-10-01

188

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

189

Deciphering Microbial Carbon Sources in Petroleum Contaminated Sediments Using Compound Specific Radiocarbon Analysis  

NASA Astrophysics Data System (ADS)

Microbial membrane phospholipid fatty acids (PLFAs) were analyzed to investigate microbial carbon sources and assess the impact of petroleum hydrocarbon contamination in one of North America's most contaminated harbours. Sediment cores were sampled from two locations in the harbour: a highly impacted area, Dofasco Boat Slip; and a less impacted area, Carole's Bay. Natural organic matter (NOM) and total petroleum hydrocarbons (TPHs) were two possible organic carbon sources for microbial metabolisms. While the majority of organic carbon (OC) at both Dofasco and Carole's Bay was NOM, petroleum hydrocarbons also contributed to the OC. As expected, the concentration of the TPHs was much greater at the Dofasco site (270 ug/g) compared to the TPHs concentration measured at Carole's Bay (50 ug/g). However, the % of PAHs that contributed to TPHs was very similar in the first three centimeters at both sites (9%). The PLFAs distributions at Carole's Bay and Dofasco were fairly similar indicating an overall bulk similarity between the communities notwithstanding higher contaminant concentrations at the Dofasco site. PLFA distributions changed with depth, consistent with changes in redox conditions from oxic to anoxia. The PLFAs extracted from the upper 3 cm of sediment from Carole's Bay had modern cap delta 14C values (with an average value of -66 ) compared to both the NOM (cap delta 14C -132 ) and TPH (cap delta 14C -775 ), suggesting that the carbon substrate for microbial metabolisms was a younger more labile source. The cap delta 14C isotopic values between individual PLFAs were indistinguishable (within the standard error of 20 for accuracy and reproducibility) demonstrating that if TPHs were degraded the impact on the cap delta 14C was not resolvable at Carole's Bay. Co-metabolic degradation of petroleum hydrocarbons is one possible degradation mechanism whereby biodegradation is occurring, but the contaminant carbon may not be incorporated into the microbial membrane PLFAs. Pure culture studies are being preformed to test this hypothesis. Data collected from Dofasco will be compared to the data from Carole's Bay.

Morrill, P. L.; Szponar, N.; Maunder, C.; Marvin, C.; Slater, G. F.

2008-12-01

190

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

SciTech Connect

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

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

2008-04-26

191

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

Microsoft Academic Search

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

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

2011-01-01

192

BIOREMEDIATION OF OIL CONTAMINATED SOIL THROUGH INOCULATION OF AN INDIGENOUS SOIL MICROBIAL COMMUNITY  

Microsoft Academic Search

The use of microbes to clean up polluted soils is a rapidly changing and expanding area of environmental biotechnology, although the mechanisms of bioremediation and the benefits which can be directly attributed to it are generally ill-defined. Microbial degradation of hydrocarbons has been measured to reduce petroleum concentrations at the soil surface by as much as 92% over two years

Sarah WIBROW; Suman J. GEORGE; Mark TIBBETT; Paul GREENWOOD; T. Ángel DELVALLS

193

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

Microsoft Academic Search

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

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

2003-01-01

194

Pilot study on the microbial contamination of conventional vs. silver-impregnated uniforms worn by ambulance personnel during one week of emergency medical service  

PubMed Central

The antimicrobial impregnation of products used everyday, such as surfaces, textiles and clothing – including those used in hospitals – is increasing. In view of potential toxic and environmental risks for users and patients, a careful risk-benefit assessment must be conducted for each newly developed product impregnated or coated with antimicrobial agents, prior to marketing and manufacture. It has been proposed that incorporation of silver threads into the clothing of emergency service workers could reduce microbial contamination over time. As clothing in the emergency services is often not adequately changed, and it is plausible that microbial contamination increases with time in use, a study was conducted in the emergency medical setting in order to test this hypothesis. We compared the contamination rates of newly developed silver-hybrid clothing with that of standard textile clothing. Samples were taken from jackets and pants of 10 emergency workers at day 0 (pre-service), day 3 and day 7 after use over a divided 4-week period to examine this hypothesis. No significant difference in the extent of microbial contamination was detected between these two materials. A larger sample size is required to further verify this result.

Gross, Raoul; Hubner, Nils; Assadian, Ojan; Jibson, Bethany; Kramer, Axel

2010-01-01

195

Herbicide Contamination of Surface Runoff Waters.  

National Technical Information Service (NTIS)

Field and laboratory studies of the movement of herbicides were conducted to determine their potential as contaminants in irrigation return flow. Special emphasis was given to the use of herbicides for vegetation control along ditches, canals and watershe...

J. O. Evans D. R. Duseja

1973-01-01

196

Microbial Diversity Under Long-Term Forcing by Acid-Mine Drainage and Metals Contamination in an Urban Wetland  

NASA Astrophysics Data System (ADS)

Few microbial diversity studies have been performed of natural wetlands under long-term forcing by acid mine drainage (AMD) and metals. Sulfate-reducing bacteria (SRB) are ubiquitous in uncontaminated wetlands and can immobilize dissolved metals as metal-sulfides (e.g. Webb et al. 1998). Sulfide-oxidizing microbes, however, will promote the formation of sulfuric acid and the release of sorbed or precipitated metals to groundwater. Therefore, understanding the balance of sulfur-cycling and other microbes from source to sink along the contaminant gradient in a natural system under long-term contamination is of primary interest to bioremediation strategies involving the use of constructed wetlands. We previously reported on bacterial diversity in sediments of the contaminated Western Stege Marsh, at the Richmond Field Station along the eastern central San Francisco Bay. This marsh has been exposed to pH 2, metal-rich groundwaters from near-surface roasted pyrite-ore tailings for over a half-century prior to recent excavation and remediation. Sediment cores were collected using sterile sampling methods at sites with pH values from 2 to 8 along a horizontal contaminant gradient in a tidal slough. 16S rDNA clone libraries from each site reveal key differences in the structure of sulfur-cycling microbial communities between sediments sampled from a standing pond of acidic brackish waters (pH 2, 25 psu) to points along the tidal slough through which this acid communicated with SF Bay tides. New data show that the acid pond sulfur-oxidizing community, in addition to the dominant Bacterial species Thiomicrospira denitrificans, contains several Archaea most closely related to Thermoplasma and environmental clones from studies of coal-refuse contaminated wetlands. Sulfate-reducing bacteria remain dominant in the structure of slough sediment communities, and seem to be effective in reducing dissolved metals concentrations to below EPA maximum contaminant or action level standards. Interestingly, SRB are also significantly present (15%) and, based on sulfur isotopic studies, remain metabolically active in acidic sediments as well. This observation reflects the capacity for some SRB to remain metabolically active in the presence of low pH conditions generally thought to be highly unfavorable for their growth.

Moreau, J. W.; Banfield, J. F.

2005-12-01

197

Recalls of foods and cosmetics due to microbial contamination reported to the U.S. Food and Drug Administration.  

PubMed

In the U.S., food product recalls serve as an important intervention in stemming the consumption of food products contaminated with infectious disease agents. We summarize the number and nature of foods and cosmetics recalled as a result of microbial contamination reported to the U.S. Food and Drug Administration (FDA) for the period 1 October 1993 through 30 September 1998. During this period, microbial contamination of food and cosmetic products was the leading cause for recalls, accounting for a total of 1,370 recalls (36% of all products recalled). Listeria monocytogenes accounted for the greatest number of food products recalled because of microbial contamination, whereas Pseudomonas aeruginosa was the most common microbe associated with recalls of cosmetic products. Dairy products, followed by seafood and pastry items, were the types of products most often associated with recalls due to microbial contamination. The FDA was the entity most often responsible for detecting microbial contamination of foods and cosmetics (33% of all such recalls), followed by state regulatory agencies (24%), and manufacturers/retailers (21%). Nineteen percent of recalls were associated with at least one reported case of illness. Salmonella was the pathogen most often implicated in reports of illness associated with these recalled products. PMID:10945589

Wong, S; Street, D; Delgado, S I; Klontz, K C

2000-08-01

198

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

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 will provide fundamental information on the attachment/detachment dynamics of anaerobic bacteria in heterogeneous porous media under growth and growth-limiting conditions. Experiments will provide information on passive and active attachment/detachment mechanisms used by growing anaerobes capable of reductive dechlorination. Theoretical representations of these attachment/detachment mechanisms will be incorporated into existing flow and transport models that incorporate heterogeneity effects and can be used to predict behavior at field scales. These mechanistic-based models will be tested against experimental data provided through controlled laboratory experiments in heterogeneous porous media in large (meter-scale) 2-D flow cells. In addition to a mechanistic-based predictive model, this research will lead to new theories for the transient spatial distribution of microbial populations and contaminant plumes in heterogeneous porous media, improving the capability for designing staged remediation strategies for dealing with mixed contaminants.'

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

1998-06-01

199

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

200

Metal contamination disturbs biochemical and microbial properties of calcareous agricultural soils of the mediterranean area.  

PubMed

Mediterranean climate characteristics and carbonate are key factors governing soil heavy-metal accumulation, and low organic matter (OM) content could limit the ability of microbial populations to cope with resulting stress. We studied the effects of metal contamination on a combination of biological parameters in soils having these characteristics. With this aim, soils were spiked with a mixture of cadmium, copper, lead, and zinc, at the two limit values proposed by current European legislation, and incubated for ?12 months. Then we measured biochemical (phosphatase, urease, ?-galactosidase, arylsulfatase, and dehydrogenase activities) and microbial (fungal and bacterial DNA concentration by quantitative polymerase chain reaction) parameters. All of the enzyme activities were strongly affected by metal contamination and showed the following inhibition sequence: phosphatase (30-64 %) < arylsulfatase (38-97 %) ? urease (1-100 %) ? ?-galactosidase (30-100 %) < dehydrogenase (69-100 %). The high variability among soils was attributed to the different proportion of fine mineral fraction, OM, crystalline iron oxides, and divalent cations in soil solution. The decrease of fungal DNA concentration in metal-spiked soils was negligible, whereas the decrease of bacterial DNA was ~1-54 % at the lowest level and 2-69 % at the highest level of contamination. The lowest bacterial DNA decrease occurred in soils with the highest OM, clay, and carbonate contents. Finally, regarding the strong inhibition of the biological parameters measured and the alteration of the fungal/bacterial DNA ratio, we provide strong evidence that disturbance on the system, even within the limiting values of contamination proposed by the current European Directive, could alter key soil processes. These limiting values should be established according to soil characteristics and/or revised when contamination is produced by a mixture of heavy metals. PMID:23183935

de Santiago-Martín, Ana; Cheviron, Natalie; Quintana, Jose R; González, Concepción; Lafuente, Antonio L; Mougin, Christian

2012-11-27

201

Microbial contamination of removable prosthodontic appliances from laboratories and impact of clinical storage.  

PubMed

Decontamination of dental instruments has recently been the subject of considerable debate. However, little information is available on the potential bacterial colonisation of dental appliances returning from dental laboratories and their need for decontamination. This study investigated the extent and nature of microbial contamination of removable prosthodontic appliances produced at different dental laboratories and stored in two clinical teaching units (CTU 1 and CTU 2) of a dental hospital and school. Forty consecutive dental prosthodontic appliances that were being stored under varying conditions in the two clinical teaching units were selected for study; the appliances having been produced 'in-house' (hospital laboratory) or 'out-of-house' (external commercial laboratory). Two appliances, that were known to have undergone decontamination before storage, were used as controls. Swabs were taken according to a standard protocol and transferred to the microbiological laboratory with bacterial growth expressed as colony forming units (cfu) per cm(2). Microbial sampling yielded growth from 23 (58%) of the 40 appliances studied (CTU 1, n = 22; CTU 2, n = 18), with 38% of these having a high level of contamination (>42,000 cfu/cm(2)). The predominant bacteria isolated were Bacillus spp. (57%), pseudomonads (22%) and staphylococci (13%). Fungi of the genus Candida were detected in 38% of the samples. There was no significant difference in contamination of the appliances in relation to either their place of production or the CTU (p >0.05). However, the level of contamination was significantly higher (p = 0.035) for those appliances stored in plastic bag with fluid (n = 16) compared to those stored on models (n = 19). No growth was recovered from the two appliances that had undergone decontamination before storage. The research showed that appliances received from laboratories are often contaminated and therefore there is a need for routine disinfection of such items before use and a review of storage conditions required. PMID:21869790

Williams, D W; Chamary, N; Lewis, M A O; Milward, P J; McAndrew, R

2011-08-26

202

An Evaluation of Microbial Community Structure and Function in Mercury Contaminated Stream Sediments  

NASA Astrophysics Data System (ADS)

Although, there has been extensive work on the presence of mercury resistance genes in mercury contaminated environments, there is a relative lack of information on the total bacterial community in highly contaminated mercury sediments. Streams draining DOE facilities in Oak Ridge, TN, have been exposed to discharges of mercury and we are examining the response of streambed microbial communities to this exposure across a Hg contamination gradient using a functional gene array (FGA) and by phylogenetic characterization (a 16s rDNA approach). The version of the FGA used for this study contains 23,864 probes covering 14,000 known microbial functional genes. We hypothesized that there would be a greater diversity of genes related to pollutants at the contaminated sites. In repeated sampling at 2-6 sites, there was a notable response in the FGA results that appears to be related to seasonal changes. We observed low numbers of genes in all categories at all sites during the winter months. Results from warmer months indicate greater differences among sites. In general, during the warmer months the contaminated sites (e.g., mercury at 33.3 ug/g and numerous other contaminants) exhibited elevated gene frequencies in all general categories compared to the control site (e.g., mercury at 0.065 ug/g). In addition to the genes that could be associated with a response to contaminants (e.g., metal resistance and contaminant degradation), genes involved in metabolism (sulfate reduction, denitrification, carbon utilization) were also elevated at the contaminated sites. We also observed an elevation in the number of different rubisco genes present with a much higher number at the most highly contaminated site compared to the control site. The only two currently completed 16s clone libraries are from these sites and interestingly the proportion of cyanobacteria is much higher in the clone library from the contaminated site. Also, the 16s diversity evident in the contaminated site is lower than that at the control site. In November 2007 (when differences among sites were reduced), a synoptic snapshot of 6 sites where total mercury in sediments ranged from 0.071ug/g to 39.1 ug/g and where there were wide ranges in concentration of SRP, nitrate, sulfate, uranium, and total organic carbon (TOC) shows that there was a poor correlation between mercury in stream sediments and mercury in the water (r = 0.71). This observation is consistent with the complex relationship between stream sediment and stream water concentration that is likely influenced by geochemical factors and mercury speciation. During this sampling, concentrations of uranium and nitrate were correlated (r = 0.71 to 0.90) with gene frequency for nitrogen cycling, sulfate cycling, metal resistance, and organic contaminant degradation. Aside from these relationships, the highest correlations (r= 0.65 and 0.66) were between TOC and gene frequency for organic contaminant degradation and sulfate and gene frequency for organic contaminant degradation. Thus, for the samples analyzed to date, the FGA appears to be able to detect differences in the diversity of genes for specific functions that can be related to site geochemistry.

Palumbo, A. V.; Brown, S. D.; Vishnivestskaya, T. A.; Drake, M.; Kerley, M. K.; Brooks, S. C.; Fagan, L. A.; Gu, B.; Rodriquez, M.; Brandt, C. C.

2008-12-01

203

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

204

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

SciTech Connect

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

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

2006-01-01

205

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

PubMed Central

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

Rodriguez-Martinez, Enid M.; Perez, Ernie X.; Schadt, Christopher W.; Zhou, Jizhong; Massol-Deya, Arturo A.

2006-01-01

206

Non-breast milk feeding in developing countries: challenge from microbial and chemical contaminants.  

PubMed

Complementary foods based on cow's milk or gruels consumed by children in developing countries are often contaminated by bacteria during preparation, and ambient temperature rapidly increases microbial load. Thus infant formula or other weaning foods may cause diarrhea in young infants accounting for 25-33% of all deaths <5 years globally. Environmental chemicals such as metals (As, Pb, Cu) and nitrates can cause vomiting/diarrhea. Polychlorinated biphenyls derived from plastics, present in formula and/or breast milk, are endocrine disruptors (the potential threats are not fully quantifiable). The prevailing view is that benefits from breastfeeding outweigh potential risks. PMID:22699772

Weisstaub, Gerardo; Uauy, Ricardo

2012-06-06

207

Characterization of Microbial Communities in TCE-Contaminated Seep Zone Sediments  

SciTech Connect

Hundreds of sites across the United States contain trichloroethene (TCE) contamination, including the Department of Energy's Savannah River Site (SRS) in Aiken, South Carolina. Previous studies have indicated that microorganisms are capable of efficiently degrading TCE to nonhazardous end products. In this project, molecular and growth based methods were used for microbial characterization of a TCE impacted seepzone where TCE degradation is naturally occurring. The results from this work provide clear evidence that the SRB may play a significant role in TCE degradation along the Twin Lakes seepline.

ROBIN, BRIGMON

2005-03-07

208

Comparison of contamination model predictions to LDEF surface measurements  

NASA Astrophysics Data System (ADS)

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

Rantanen, Raymond; Gordon, Tim; Finckenor, Miria M.; Pippin, Gary

1998-10-01

209

TRACE ORGANIC CONTAMINANTS IN ANTHROPOGENICALLY ACIDIFIED SURFACE WATERS  

EPA Science Inventory

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

210

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

USGS Publications Warehouse

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

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

1988-01-01

211

Evaluation of secondary contamination in laser cutting of surface-contaminated metals  

Microsoft Academic Search

We investigated the mixing of simulated surface contamination in the cut surfaces of laser-cut stainless steel. A 10 micrometers layer of molybdenum was coated by wire explosion spraying of 8mm-thick 304L stainless steel to serve as the simulated contaminated metal plate. The cutting was done with a CO2 laser using a nitrogen and oxygen gas mixture as cutting assist gas.

Kunimitsu Takahashi; Shunichi Sato; Tadashi Fukushima; Akira Sano; Yasuhisa Ikeda; Yoich Takashima

2000-01-01

212

The role of microbial surface properties and extracellular polymer in Lactococcus Lactis aggregation  

Microsoft Academic Search

Microbial adhesion to an interface is known to have an important role in a wide variety of situations. In this study, we examine the effect of the surface physicochemical properties and extracellular polymers (ECP) of a lactic bacterium on microbial aggregation. Lactococcus lactis JCM 5805 was used in the current experiments to investigate the factors that control microbial aggregation. To

Toshiyuki Nomura; Hisaya Narahara; Hayato Tokumoto; Yasuhiro Konishi

2009-01-01

213

Characterization of Groundwater Microbial Communities from a Chlorinated-Ethene-Contaminated Landfill  

SciTech Connect

Molecular (rDNA), phospholipid fatty acid analysis (PLFA), and substrate utilization (BIOLOG) techniques were used to assess structural and functional differences between groundwater microbial communities from a chlorinated-ethene (CE)-contaminated landfill. Prokaryotic cells were collected from pristine (LFW 43B) and CE-contaminated (LFW 62D) groundwater monitoring wells on 0.2 micron filters, DNA was extracted from the filters, and libraries were prepared. For well LFW 43B, 26 clones were examined by sequencing and restriction endonuclease patterns, and all were found to be closely related to Pseudomonas gessardii and P. libaniensis. For well LFW 62D, 40 bacterial clones were examined, and 17 ribotypes were found including representatives of type I and II methylotrophs, Pseudomonas spp., Zoogloea spp., and other proteobacteria. In an archaeal library from well LFW 62D, all 15 of the clones examined were nearly identical and possessed about 89 percent sequence similarity to Cenarchaeum symbiosum. PLFA analysis revealed that the communities from contaminated groundwater contained primarily gram-negative bacteria, as indicated by the predominance of the biomarker 16:1w7c. The bacteria were in the stationary growth phase as indicated by the abundance of cyclopropyl fatty acids cy17:0 and cy19:0 and their respective precursors 16:1w7c and 18:1w7c. Further, PLFA ratios for 16:1w7t/16:1w7c and 18:1w7t/18:1w7c were greater than 0.1, indicative of increased cellular membrane permeability. Using BIOLOG GN plates, a similar number of substrates were utilized in LFW43B (72) and LFW 62D (63) communities, even though inoculum densities were 2-orders of magnitude greater in LFW 62D. The combination of non-selective characterization techniques was useful to further our understanding of CE-contamination on groundwater microbial communities.

Brigmon, R.L.

2002-11-20

214

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

215

Modeling of laser damage initiated by surface contamination  

SciTech Connect

The authors are engaged in a comprehensive effort to understand and model the initiation and growth of laser damage initiated by surface contaminants. This includes, for example, the initial absorption by the contaminant, heating and plasma generation, pressure and thermal loading of the transparent substrate, and subsequent shockwave propagation, `splashing` of molten material and possible spallation, optical propagation and scattering, and treatment of material fracture. The integration use of large radiation hydrodynamics codes, optical propagation codes and material strength codes enables a comprehensive view of the damage process The following picture of surface contaminant initiated laser damage is emerging from our simulations.

Feit, M.D.; Rubenchik, A.M.; Faux, D.R.; Riddle, R.A.; Shapiro, A.; Eder, D.C.; Penetrante, B.M.; Milam, D.; Genin, F.Y.; Kozlowski, M.R.

1996-11-01

216

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

SciTech Connect

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

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

1992-10-01

217

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

SciTech Connect

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

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

1992-10-01

218

Automatic Measurement of Low Level Contamination on Concrete Surfaces  

SciTech Connect

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

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

2002-02-28

219

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.

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

2012-01-01

220

Processing efficacy in relation to microbial contamination of skin allografts from 723 donors.  

PubMed

The Siena Skin Bank, established in 2000, processes skin from more than 130 cadaveric donors per year (about 400,000 cm(2)) and distributes it for transplants to treat burns and other types of skin loss. More than 1,500,000 cm(2) of homologous skin has been transplanted to date. At the Siena Skin Bank we conducted a retrospective study of our data to assess microbial contamination of skin specimens from 723 donors banked in the period 2000-2007. Our aim was to determine factors deleterious for skin quality, to optimize skin banking procedures and to reduce corrective actions. The factors analyzed were: type of donor (multi-organ, multi-tissue, live or cadaver), cause of death, time elapsing between death and procurement, different procurement centres and operator experience. Of the 723 donors considered, 26.55% (192/723) were positive for microbes, 22.68% (164) for bacteria and 5.39% (39) for mycetes. Of these 192 positives, 82 (42.70%) required corrective actions. The data obtained showed that the only variables significantly affecting microbial contamination of tissue were type of donor (live or cadaver) and type of processing (cryo- or glycerol preservation). PMID:19616385

Pianigiani, E; Ierardi, F; Cuciti, C; Brignali, S; Oggioni, M; Fimiani, M

2009-07-17

221

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

222

Resistance of SolidPhase U(VI) to Microbial Reduction during In Situ Bioremediation of Uranium-Contaminated Groundwater  

Microsoft Academic Search

Received 21 June 2004\\/Accepted 28 July 2004 Speciation of solid-phase uranium in uranium-contaminated subsurface sediments undergoing uranium bioremediation demonstrated that although microbial reduction of soluble U(VI) readily immobilized uranium as U(IV), a substantial portion of the U(VI) in the aquifer was strongly associated with the sediments and was not microbially reducible. These results have important implications for in situ uranium

Irene Ortiz-Bernad; Robert T. Anderson; Helen A. Vrionis; Derek R. Lovley

2004-01-01

223

Resistance of Solid-Phase U(VI) to Microbial Reduction during In Situ Bioremediation of Uranium-Contaminated Groundwater  

PubMed Central

Speciation of solid-phase uranium in uranium-contaminated subsurface sediments undergoing uranium bioremediation demonstrated that although microbial reduction of soluble U(VI) readily immobilized uranium as U(IV), a substantial portion of the U(VI) in the aquifer was strongly associated with the sediments and was not microbially reducible. These results have important implications for in situ uranium bioremediation strategies.

Ortiz-Bernad, Irene; Anderson, Robert T.; Vrionis, Helen A.; Lovley, Derek R.

2004-01-01

224

Contribution of dietary purine bases to duodenal digesta in sheep. In situ studies of purine degradability corrected for microbial contamination  

Microsoft Academic Search

The dietary contribution of purine bases (PB) to duodenal flow was evaluated by the in situ method after correcting for microbial contamination using 15N as microbial marker and rumen solid associated bacteria as reference sample. Four ruminally fistulated sheep were offered at 4 h intervals a mixed diet 2:1 vetch-oat hay:concentrate, and 179 mg of ((15NH4)2SO4) were continuously infused in

J. F. Perez; C. A. Rodriguez; J. Gonzalez; J. Balcells; J. A. Guada

1996-01-01

225

LASER CLEANING OF CONTAMINATED PAINTED SURFACES  

SciTech Connect

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

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

1999-11-19

226

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

Microsoft Academic Search

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

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

2003-01-01

227

Air sampling procedures to evaluate microbial contamination: a comparison between active and passive methods in operating theatres  

PubMed Central

Background Since air can play a central role as a reservoir for microorganisms, in controlled environments such as operating theatres regular microbial monitoring is useful to measure air quality and identify critical situations. The aim of this study is to assess microbial contamination levels in operating theatres using both an active and a passive sampling method and then to assess if there is a correlation between the results of the two different sampling methods. Methods The study was performed in 32 turbulent air flow operating theatres of a University Hospital in Southern Italy. Active sampling was carried out using the Surface Air System and passive sampling with settle plates, in accordance with ISO 14698. The Total Viable Count (TVC) was evaluated at rest (in the morning before the beginning of surgical activity) and in operational (during surgery). Results The mean TVC at rest was 12.4?CFU/m3 and 722.5?CFU/m2/h for active and passive samplings respectively. The mean in operational TVC was 93.8?CFU/m3 (SD?=?52.69; range?=?22-256) and 10496.5?CFU/m2/h (SD?=?7460.5; range?=?1415.5-25479.7) for active and passive samplings respectively. Statistical analysis confirmed that the two methods correlate in a comparable way with the quality of air. Conclusion It is possible to conclude that both methods can be used for general monitoring of air contamination, such as routine surveillance programs. However, the choice must be made between one or the other to obtain specific information.

2012-01-01

228

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

PubMed

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

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

2013-06-20

229

Impact of nanoscale zero valent iron on geochemistry and microbial populations in trichloroethylene contaminated aquifer materials.  

PubMed

Nanoscale zerovalent iron (NZVI) particles are a promising technology for reducing trichloroethylene (TCE) contamination in the subsurface. Prior to injecting large quantities of nanoparticles into the groundwater it is important to understand what impact the particles will have on the geochemistry and indigenous microbial communities. Microbial populations are important not only for nutrient cycling, but also for contaminant remediation and heavy metal immobilization. Microcosms were used to determine the effects of NZVI addition on three different aquifer materials from TCE contaminated sites in Alameda Point, CA, Mancelona, MI, and Parris Island, SC. The oxidation and reduction potential of the microcosms consistently decreased by more than 400 mV when NZVI was added at 1.5 g/L concentrations. Sulfate concentrations decreased in the two coastal aquifer materials, and methane was observed in the presence of NZVI in Alameda Point microcosms, but not in the other two materials. Denaturing gradient gel electrophoresis (DGGE) showed significant shifts in Eubacterial diversity just after the Fe(0) was exhausted, and quantitative polymerase chain reaction (qPCR) analyses showed increases of the dissimilatory sulfite reductase gene (dsrA) and Archaeal 16s rRNA genes, indicating that reducing conditions and hydrogen created by NZVI stimulate both sulfate reducer and methanogen populations. Adding NZVI had no deleterious effect on total bacterial abundance in the microcosms. NZVI with a biodegradable polyaspartate coating increased bacterial populations by an order of magnitude relative to controls. The lack of broad bactericidal effect, combined with the stimulatory effect of polyaspartate coatings, has positive implications for NZVI field applications. PMID:20350000

Kirschling, Teresa L; Gregory, Kelvin B; Minkley, Edwin G; Lowry, Gregory V; Tilton, Robert D

2010-05-01

230

Surface contamination effects on resistance of gold nanowires  

SciTech Connect

Gold nanowires were patterned with e-beam lithography and fabricated with a gold film deposited by e-beam evaporation. The resistances of these wires were measured and found to be nonlinear with respect to surface area/volume. With x-ray photoelectron spectroscopy analysis, carbon and oxygen contaminants in the forms of C, C-O-C, and C=O were found adsorbed on the gold surface. This contamination adsorbed on the surface may lead to increased resistance of nanowires.

Lilley, Carmen M.; Huang, Qiaojian [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor Street (MC 251), Chicago, Illinois 60607 (United States)

2006-11-13

231

Signature analysis of flashover voltage phenomena on contaminated insulator surfaces  

Microsoft Academic Search

This paper discusses some of the physical process involved in the flashover of non-ceramic and ceramic contaminated insulator surfaces. The various discharges and flashover voltage (FOV) phenomena on insulator surfaces (nonceramic vs. ceramic) were investigated by means of slow and fast oscillographic recording of the discharge current. Discharge current signatures were analyzed by means of fast Fourier transform (FFT). It

Mirresh Shah

1996-01-01

232

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

2011-10-01

233

Microbial contamination of embryos and semen during long term banking in liquid nitrogen.  

PubMed

We report on microbial contamination of embryos and semen cryopreserved in sealed plastic straws and stored for 6-35 years in liquid nitrogen. There were 32 bacterial and 1 fungal species identified from randomly drawn liquid nitrogen, frozen semen, and embryos samples stored in 8 commercial and 8 research facility liquid nitrogen (LN) tanks. The identified bacteria represented commensal or environmental microorganisms and some, such as Escherichia coli, were potential or opportunistic pathogens for humans and animals. Stenotrophomonas maltophilia was the most common contaminant identified from the samples and was further shown to significantly suppress fertilization and embryonic development in vitro. Analysis of the strains by pulsed field gel electrophoresis revealed restriction patterns with no relatedness indicating that there was no apparent cross-contamination of S. maltophilia strains between the germplasm and liquid nitrogen samples. In addition, no transmission of bovine viral diarrhea virus (BVDV) and bovine herpesvirus-1 (BHV-1) from infected semen and embryos straws to clean germplasm stored in the same LN tanks or LN was detected. PMID:12686204

Bielanski, A; Bergeron, H; Lau, P C K; Devenish, J

2003-04-01

234

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

Microsoft Academic Search

Soil contamination due to petroleum-derived products is an important environmental problem. We assessed the impacts of diesel oil on plants (Trifolium repens and Lolium perenne) and soil microbial community characteristics within the context of the rhizoremediation of contaminated soils. For this purpose, a diesel fuel spill on a grassland soil was simulated under pot conditions at a dose of 12,000mgdieselkg?1

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

2011-01-01

235

Spatial variations in nutrient and microbial transport from feedlot surfaces  

Technology Transfer Automated Retrieval System (TEKTRAN)

Nutrient and microbial transport by runoff may vary at different locations within a beef cattle feedlot. If the areas making the greatest contributions to nutrient and microbial transport can be identified, it may be possible to institute precision management practices to reduce nutrient and microbi...

236

Aquatic Surface Microlayer Contamination in Chesapeake Bay.  

National Technical Information Service (NTIS)

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 throughou...

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

1987-01-01

237

Evaluation of secondary contamination in laser cutting of surface-contaminated metals  

NASA Astrophysics Data System (ADS)

We investigated the mixing of simulated surface contamination in the cut surfaces of laser-cut stainless steel. A 10 micrometers layer of molybdenum was coated by wire explosion spraying of 8mm-thick 304L stainless steel to serve as the simulated contaminated metal plate. The cutting was done with a CO2 laser using a nitrogen and oxygen gas mixture as cutting assist gas. The mixing of the molybdenum into the cut walls was evaluated by EPMA surface analysis and fluorescent x-ray analysis. The result revealed that the degree to which the molybdenum was mixed into the cut surfaces decreased as the concentration of oxygen in the assist gas increased. Also, the result of contaminant removal from the cut piece by chemical oxidation reduction decontamination processing was that the greater the oxidation, the less the molybdenum that remained after the processing. Thus, to reduce the mixing of simulated surface contaminants in the cut surfaces, a cutting assist gas that has a high concentration of oxygen should be used.

Takahashi, Kunimitsu; Sato, Shunichi; Fukushima, Tadashi; Sano, Akira; Ikeda, Yasuhisa; Takashima, Yoich

2000-01-01

238

Management of risk of microbial cross-contamination from uncooked frozen hamburgers by alcohol-based hand sanitizer.  

PubMed

This research was undertaken to determine the effectiveness of an alcohol-based hand sanitizer on hands contaminated with a nonpathogen surrogate for Escherichia coli O157:H7, where the source of the contamination was frozen hamburger patties. A nonpathogenic nalidixic acid-resistant food-grade strain of Enterobacter aerogenes was used to inoculate frozen hamburger patties composed of 76% lean beef and 24% fat. Thirty-two individuals participated to produce the data used in this study. Each participant handled nine patties at least three times, a sample for microbiological analysis was collected from the surface of one hand, the participant sanitized both hands, and a sample was collected from the other hand. Burger handling created perceptible and visible food debris on the hands of most participants. Computer simulations also were used to perform a variety of risk calculations. The average reduction in bacteria from the use of sanitizer on hands contaminated by frozen burgers containing E. aerogenes was 2.6 +/- 0.7 log CFU per hand. An experiment designed to simultaneously test the effect of sanitizer on E. aerogenes and E. coli O157:H7 also revealed no significant difference in sanitizer effectiveness against the two organisms. The results of the real-world risk estimation calculations (using the actual prevalence and concentration of E. coli O157:H7 in ground beef) predict that once in 1 million trials, a single pathogen cell will be transferred to a single lettuce piece. The effectiveness of this sanitizer intervention was similar to that for hand washing and glove use previously reported. The person-to-person microbial reduction variability from sanitizer use is similar to published data for glove use and was less variable than published data on hand washing effectiveness. PMID:17265868

Schaffner, Donald W; Schaffner, Kristin M

2007-01-01

239

Analysis of surface contaminants on beryllium windows  

SciTech Connect

It is known that various crystalline and liquid compounds form on the downstream surfaces of beryllium windows exposed to air. It is also known that the integrity of such windows may be compromised resulting in leaks through the window. The purpose of this report is to document the occurrences described as they pertain to the NSLS and to analyze, where possible, the various substances formed.

Gmur, N.F.

1986-12-01

240

UV/Ozone treatment to decontaminate tritium contaminated surfaces  

SciTech Connect

Tritium contamination on surfaces is often encountered during operation and maintenance of equipment at the Darlington Tritium Removal Facility and likely at other tritium handling facilities. The use of efficient decontamination techniques that produce little or no secondary wastes is desirable. At Ontario Hydro Technologies (OHT) we have been developing a process utilizing a combination of ultraviolet (UV) radiation and ozone gas to remove tritium surface contamination from materials often used in tritium service. This paper summarizes the performance of the technique. The results are encouraging because the technique is very effective, simple in terms of equipment requirements and concentrates tritium in an easily managed waste form. 7 refs., 3 figs., 2 tabs.

Krasznai, J.P.; Mowat, R. [Ontario Hydro Technologies, Toronto, Ontario (Canada)

1995-10-01

241

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

Abulencia, Carl B [Diversa Corporation; Wyborski, Denise L. [Diversa Corporation; Garcia, Joseph A. [Diversa Corporation; Podar, Mircea [ORNL; Chen, Wenqiong [Diversa Corporation; Chang, Sherman H. [Diversa Corporation; Chang, Hwai W. [Diversa Corporation; Watson, David B [ORNL; Brodie, Eoin L. [Lawrence Berkeley National Laboratory (LBNL); Hazen, Terry [Lawrence Berkeley National Laboratory (LBNL); Keller, Martin [ORNL

2006-05-01

242

Measuring electric fields from surface contaminants with neutral atoms  

SciTech Connect

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

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

2007-06-15

243

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

244

Jamu Gendong, a kind of traditional medicine in Indonesia: the microbial contamination of its raw materials and endproduct  

Microsoft Academic Search

An examination on the microbiological quality of seven kinds of Jamu Gendong (JG) and their raw materials has been conducted according to the requirements of microbial contamination in traditional medicine, issued by the Department of Health of Indonesia in 1986. Samples of JG and their raw materials were taken from producers in three districts of Surabaya. The samples were subject

D. A Limyati; B. L. L Juniar

1998-01-01

245

Study of natural mango juice spoilage and microbial contamination with Penicillium expansum by high resolution 1H NMR spectroscopy  

Microsoft Academic Search

High resolution 1H NMR has been applied to monitor the changes in the composition of natural mango juice subjected to spoilage and to microbial contamination with Penicillium expansum. A vast number of compounds undergoing changes upon these processes have been identified and their variations followed throughout time (132h). Besides the formation of typical fermentation products (e.g. acetate, lactic acid, acetoin

Iola F. Duarte; Ivonne Delgadillo; Ana M. Gil

2006-01-01

246

Taxonomic profiling and metagenome analysis of a microbial community from a habitat contaminated with industrial discharges.  

PubMed

Industrial units, manufacturing dyes, chemicals,solvents, and xenobiotic compounds, produce liquid and solid wastes, which upon conventional treatment are released in the nearby environment and thus are the major cause of pollution. Soil collected from contaminated Kharicut Canalbank (N 22°57.878?; E 072°38.478?), Ahmeda bad, Gujarat,India was used for metagenomic DNA preparation to study the capabilities of intrinsic microbial community in dealing with xenobiotics. Sequencing of metagenomic DNA on the Genome Sequencer FLX System using titanium chemistry resulted in 409,782 reads accounting for 133,529,997 bases of sequence information. Taxonomic analyses and gene annotations were carried out using the bioinformatics platform Sequence Analysis and Management System for Metagenomic Datasets. Taxonomic profiling was carried out by three different complementary approaches: (a) 16S rDNA, (b) environmental gene tags, and (c) lowest common ancestor. The most abundant phylum and genus were found to be “Proteobacteria”and “Pseudomonas,” respectively. Metagenome reads were mapped on sequenced microbial genomes and the highest numbers of reads were allocated to Pseudomonas stutzeri A1501. Assignment of obtained metagenome reads to Gene Ontology terms, Clusters of Orthologous Groups of protein categories, protein family numbers, and Kyoto Encyclopedia of Genes and Genomes hits revealed genomic potential of indigenous microbial community. In total, 157,024 reads corresponded to 37,028 different KEGG hits, and amongst them, 11,574 reads corresponded to 131 different enzymes potentially involved in xenobiotic biodegradation. These enzymes were mapped on biodegradation pathways of xenobiotics to elucidate their roles in possible catalytic reactions. Consequently, information obtained from the present study will act as a baseline which, subsequently along with other“-omic” studies, will help in designing future bioremediation strategies in effluent treatment plants and environmental cleanup projects. PMID:23728164

Shah, Varun; Zakrzewski, Martha; Wibberg, Daniel; Eikmeyer, Felix; Schlüter, Andreas; Madamwar, Datta

2013-10-01

247

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

248

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

249

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

250

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

PubMed

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

Okwadha, George D O; Li, Jin

2011-06-21

251

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

NASA Astrophysics Data System (ADS)

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

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

2008-09-01

252

Microbial diversity and resistance to copper in metal-contaminated lake sediment.  

PubMed

Contamination of habitats with heavy metals has become a worldwide problem. We describe herein the analysis of lake sediment contaminated with high concentrations of copper as a consequence of mine milling disposal over a 100-year period. Copper concentrations in the sediment were found to vary with depth and ranged from 200 to 5500 ppm. Analysis of the microbial community with T-RFLP identified a minimum of 20 operational taxonomic units (OTU). T-RFLP analysis along a depth profile detected as many as nine shared OTUs across 15 centimeters, suggesting a conservation of community structure over this range. Only two genera, Arthrobacter and Ralstonia, were detected among 50 aerobic copper-resistant isolates cultivated on R2A, one of which (Ralstonia sp.) was characterized by the sequestration of copper, identified by electron diffraction scanning, in growing colonies. Scanning electron microscopy showed changes to the outer envelope of the cells when grown in the presence of copper. The copper-resistant Ralstonia isolates were also resistant to Ni, Cd, and Zn, showing two patterns of phenotypic resistant to these three metals in which either resistance to Zn or Ni was expressed in an isolate but never both. PMID:12545313

Konstantinidis, K T; Isaacs, N; Fett, J; Simpson, S; Long, D T; Marsh, T L

2003-01-28

253

Screening of microbial contamination and antimicrobial activity of sea cucumber Holothuria polii.  

PubMed

Microbiological studies were carried out on microbial contamination and antimicrobial activity of sea cucumber Holothuria polii collected from Mediterranean Sea at Abu-kir shore of Alexandria, Egypt. The obtained results revealed the presence of isolates of five human Gram-negative pathogenic bacteria, representing five genera were identified to species level, including, Esherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella sp. and Shigella sp. In addition, an yeast Candida albicans was isolated. The pathogenic bacteria were identified using API 20E strip system (BioMereux). All collected H. polii specimens were healthy with no external signs of infection. Histopathological study of the tegument, intestine and gonads showed no abnormal changes. The antimicrobial activity of two tegumental ethanol extracts (A and B, differ in the method of dehydration) were tested against wide range of pathogenic bacteria and fungi, including intestinal, skin and nosocomial pathogens and one plant fungal pathogen. The results revealed a remarkable antifungal activity of the extract B at 2.5 mg/ml MIC90, especially on Aspergillus niger, Scloretium sp, C. albicans, Aspergillus flavus and Malassezia furfur, and limited antibacterial activity against Gram-negative bacteria (Salmonella choleraesuis ATCC 14028 and Aeromonas hydrophila). The domain of bacterial and limited fungal contamination confirms the results that showed strong antifungal activity of investigated extract. PMID:22653870

Omran, Nahla Ee; Allam, Nanis G

2012-05-31

254

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

PubMed

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

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

2012-09-13

255

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

256

XUV projection lithography: is optical surface contamination an important limitation?  

Microsoft Academic Search

We report results of an extensive set of oxide and carbon film contamination experiments with Al, Si, Rh, and Ag films and surfaces to quantify the film growth rates and parameter dependencies. These four materials were selected initially because they exhibit total external reflectance at moderate angles of incidence, e.g., > 45 degree(s), as needed for high- reflectance multifacet mirrors.

Marion L. Scott; Brian E. Newnam

1993-01-01

257

PERFORMANCE OF HYPERSPECTRAL IMAGING SYSTEM FOR POULTRY SURFACE CONTAMINANT DETECTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

A hyperspectral imaging system demonstrated potential to detect surface fecal and ingesta contaminants on poultry carcasses. Hyperspectral data were analyzed with four pre-processing methods considering two parameters: calibration and 20-nm spectral smoothing. A band-ratio image-processing algorit...

258

RESUSPENSION OF PLUTONIUM FROM CONTAMINATED LAND SURFACES: METEOROLOGICAL FACTORS  

EPA Science Inventory

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

259

UV\\/Ozone treatment to decontaminate tritium contaminated surfaces  

Microsoft Academic Search

Tritium contamination on surfaces is often encountered during operation and maintenance of equipment at the Darlington Tritium Removal Facility and likely at other tritium handling facilities. The use of efficient decontamination techniques that produce little or no secondary wastes is desirable. At Ontario Hydro Technologies (OHT) we have been developing a process utilizing a combination of ultraviolet (UV) radiation and

J. P. Krasznai; R. Mowat

1995-01-01

260

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.

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

2013-01-01

261

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

2013-04-16

262

Microbial contamination of contact lens storage cases and domestic tap water of contact lens wearers.  

PubMed

Contact lenses have been widely used as an alternative to spectacles both in developed and developing countries. However, under certain circumstances, adverse responses can occur during contact lens wear and several microorganisms--including bacteria, fungi, and free living amoebae--can cause several eye infections in wearers. Extended wear of contact lenses is the major risk factor of eye infections such as microbial keratitis, besides contaminated contact lens storage case, contaminated lens care solutions, and inaccurate contact lens handling. In this study, we collected contact lens storage case and domestic tap water samples from 50 asymptomatic contact lens wearers. We determined that total aerobic mesophilic bacteria were isolated in 45 (90 %), Gram negative rod bacteria were isolated in 20 (40 %), Pseudomonas spp. were isolated in 2 (4 %) and fungi were isolated in 18 (36 %) out of 50 contact lens storage cases. Free living amoebae were not detected in investigated contact lens storage cases. At the same time, out of 50, total aerobic mesophilic bacteria were isolated in 34 (68 %), fungi were isolated in 15 (30 %) and free living amoebae were isolated in 15 (30 %) domestic tap water samples. No Gram-negative rod bacteria and Pseudomonas spp. were detected in investigated water samples. Two contact lens case samples and two tap water samples were excluded from the analysis for Pseudomonas spp. for technical reasons. According to our findings, inadequate contact lens maintenance during lens wear may result in the contamination of contact lens storage cases. This situation can lead to severe eye infections in contact lens wearers over time. PMID:23064864

Üstüntürk, Miray; Zeybek, Zuhal

2012-10-13

263

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

SciTech Connect

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

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

2006-09-30

264

Radon-induced surface contaminations in low background experiments  

NASA Astrophysics Data System (ADS)

In low background experiments the reduction of all possible radioactive contaminants is a crucial point for detector construction. This is also true for the surface contaminants, either those introduced during the production of detector components or those introduced during handling, treatment or storage. One of the most critical issue in this field is the control of the contamination induced by 222Rn and its progenies in the environment where the detectors are assembled and stored. Radioactive atoms can stick on detector components and create a net increase of the contaminants present on their surfaces, introducing an additional—often not negligible—source of background. The reduction of this kind of contaminations can become of primary importance in the case of fully sensitive devices, like cryogenic particle detectors. In this paper the analysis on the Rn sticking factor for copper and tellurium dioxide—the two main materials used for the construction of the CUORE detector—is discussed. The diffusion of radioactive atoms inside the detector components is considered in order to evaluate the effective contribution of Rn exposure to the background counting rate of an experiment.

Clemenza, M.; Maiano, C.; Pattavina, L.; Previtali, E.

2011-11-01

265

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

266

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

267

Formation of surface superstructures by heat treatments on Ni-contaminated surface of Si(110)  

NASA Astrophysics Data System (ADS)

On clean and Ni-contaminated surfaces of Si(110), experiments of low-energy electron diffraction (LEED) and Auger-electron spectroscopy (AES) were carried out under various heat treatments. The Si(110) clean surface has a ``16×2'' structure and it transforms reversibly to 1×1 at 740 °C. On the other hand, Ni-contaminated surfaces exhibit several surface superstructures at room temperature, e.g., the 4×5, 2×1, and 5×1, depending on the heat treatments. Moreover, it is found that these structures are closely correlated with Ni concentration at the surface. Quantitative Auger-electron analyses show that a thickness of the Ni-contaminated layer varies from several angstroms to 20 Å and the surface Ni concentration changes from 7% to 1%, depending on the heat treatment. These variations give rise to changes of the surface superstructure depending on the heat treatment.

Ichinokawa, T.; Ampo, H.; Miura, S.; Tamura, A.

1985-04-01

268

Surface Contaminants Inhibit Osseointegration in a Novel Murine Model  

PubMed Central

Surface contaminants, such as bacterial debris and manufacturing residues, may remain on orthopaedic implants after sterilization procedures and affect osseointegration. The goals of this study were to develop a murine model of osseointegration in order to determine whether removing surface contaminants enhances osseointegration. To develop the murine model, titanium alloy implants were implanted into a unicortical pilot hole in the mid-diaphysis of the femur and osseointegration was measured over a five week time course. Histology, backscatter scanning electron microscopy and x-ray energy dispersive spectroscopy showed areas of bone in intimate physical contact with the implant, confirming osseointegration. Histomorphometric quantification of bone-to-implant contact and peri-implant bone and biomechanical pullout quantification of ultimate force, stiffness and work to failure increased significantly over time, also demonstrating successful osseointegration. We also found that a rigorous cleaning procedure significantly enhances bone-to-implant contact and biomechanical pullout measures by two-fold compared with implants that were autoclaved, as recommended by the manufacturer. The most likely interpretation of these results is that surface contaminants inhibit osseointegration. The results of this study justify the need for the development of better detection and removal techniques for contaminants on orthopaedic implants and other medical devices.

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

2011-01-01

269

FTIR Study on Molecular Contamination on Surface of Optical Materials  

Microsoft Academic Search

The IR spectra of the molecular contaminants on surface of optical materials were measured. The optical disks used were SiO2, BK7 (SiO2 70%, B2O3 10%, K2O 8%, N2O 8%), CaF2, ZnSe and Al2O3. N2, O2, H2O, and CO2 were adopted as contamination gases. IR spectra of H2O (2.7kPa) on BK7 at 373K showed two absorption bands (OH stretching vibration: around

Masahiro Katoh; Nobuaki Okano; Toshihide Horikawa; Tahei Tomida; Nobunari Itoh

2006-01-01

270

Efficacy of a Passive Diffusion Sampler to Assess Microbial Spatial Dynamics in a Contaminated Aquifer-wetland System  

NASA Astrophysics Data System (ADS)

Microbiological processes affect biogeochemical cycling of nutrients and contaminants in subsurface systems. Microbial response to changes in terminal electron accepting processes (TEAPs), and in turn the microbes' effect on TEAP distribution are critical to understanding the fate and transport of contaminants. A challenge to studying microbial processes is obtaining samples that yield enough biomass to assess microbial communities and are spatially and temporally representative of changes in water chemistry. Our study focuses on the interface between ground water affected by landfill leachate at the closed Norman, Oklahoma landfill and porewater in a slough adjacent to the landfill (a contaminated aquifer-wetland system). We used a combination of more traditional and newer molecular microbiological approaches to provide an extension of the biochemical and culture approaches commonly employed in studies of microbial processes in subsurface environments. In order to enable contemporaneous and spatially concordant sampling of water chemistry and microbiology, passive diffusion samplers containing sponge material at discrete intervals were installed in the slough sediment. Unlike peeper diffusion samplers, the sampler installed is porous enough to allow native organisms to flow through the device and colonize the substrate. In addition to obtaining critical biomass, this setup allows us to extract nucleic acids easily while minimizing the affect of inhibitors to molecular analyses that are found commonly in organic rich sediments and contaminated systems. Discrete interval microbe samplers (DIMPS, Geosyntec) were deployed at 2 sites in the Norman Landfill slough and allowed to equilibrate for 14 days before retrieval and removal of sponge substrate at 14 depth intervals. Cores were taken near the passive diffusion samplers, sectioned for Most Probable Number (MPN) analysis and assessed by quantitative PCR (qPCR) for microbial abundance of metabolically important microorganisms (e.g., sulfate reducing bacteria, Geobacter (proxy for Fe reduction) and methanogens). The same qPCR analyses were performed on nucleic acids extracted from the DIMPS sponges. Water chemistry (including aqueous Fe2+, H2S, CH4) was measured also at discrete intervals from simultaneous deployment of peeper samplers. Results at the two sites demonstrate that the DIMPS could be a valuable tool for investigating the microbial dynamics between different parts of the slough but do not resolve fine scale interface microbial structure as well as actually sampling and analyzing cores. The samplers could be valuable also in in situ experiments, baited with limiting terminal electron acceptors as a method to look at community responses to changing chemical environments, providing additional information necessary to begin to quantify the extent to which microbial response controls changes in TEAPs.

Kirshtein, J. D.; Kneeshaw, T. A.; Voytek, M. A.; Cozzarelli, I. M.; McGuire, J. T.; Baez Cazull, S.

2006-05-01

271

Preventing Microbial Contamination during Long-Term In Vitro Culture of Human Granulosa-Lutein Cells: An Ultrastructural Analysis  

PubMed Central

Purpose. To investigate whether the addition of antibiotic/antimycotic during human granulosa-lutein cells (GLCs) isolation and cell-plating procedures prevents microbial contamination after 144?h of culture and also evaluate the effects of contamination on GLCs ultrastructure and steroid secretion. Methods. GLCs obtained from five women submitted to assisted reproductive techniques (ARTs) were isolated with PBS supplemented with antibiotic/antimycotic or PBS nonsupplemented and cultured for 144?h. GLCs were evaluated by transmission electron microscopy (TEM), and estradiol (E2) and progesterone (P4) secretion was assayed by chemiluminescence. Results. Although no contaminating microorganisms were identified by light microscopy, TEM analyses revealed several bacterial colonies in culture dishes of GLCs isolated with only PBS. Bacterial contamination disrupted the adherence of the GLCs to the culture plate interfering with monolayer formation affecting the growth pattern of GLCs. Various cellular debris and bacteria were observed, and no organelles were found in the cytoplasm of infected cells. While bacterial contamination decreased estradiol media levels, it increased progesterone, as compared with noncontaminated group. Conclusion. Taken together, our data showed that the addition of a high dose of antibiotic/antimycotic during the isolation and cell-plating procedures prevents microbial contamination of long-term GLCs culture as its effects on cells growth and function in vitro.

Campos, C. O.; Bernuci, M. P.; Vireque, A. A.; Campos, J. R.; Silva-de-Sa, M. F.; Jamur, M. C.; Rosa-e-Silva, A. C. J. S.

2012-01-01

272

Microbial contamination of the environment after the irradiation of Er:YAG laser in infected root canals  

NASA Astrophysics Data System (ADS)

The purpose of this study was to analyze the environment microbial contamination produced by Er:YAG laser irradiation in infected root canals. A total of 20 human anterior teeth were prepared, sterilized and, then, inoculated with a mixture of the following microorganisms: S. Aureus, E. Faecalis, P. Aeruginosa, B. Subtilis and C. Albicans. After the contamination period (28 days), the teeth were irrigated with sterile distilled water or 1% sodium hypochlorite and, then, irradiated with an Er:YAG laser with two different laser parameters: 52 mJ or 110 mJ output at the fiber tip. Eighteen Petri dishes with 20 ml of BHI Agar were used in the study. For each group, 3 plates with BHIA were used for the analysis of the microbial contamination of the environment during the activation of the laser in infected root canals. The plates were positioned in differing distances away from the irradiated tooth (plate 1 distance of 15 cm, plate 2 distance of 50 cm and plate 3 distance of 3 meters). After the analysis of the results, it was observed that the larger microbial contamination occurred in Group 1 (teeth irrigated with sterile distilled water and irradiated with Er:YAG laser with 52 mJ output at the fiber tip), plate 1 (positioned 15 cm away from the irradiated tooth), with values greater than 30 Colony-Forming Units (CFU).

Brugnera, Aldo, Jr.; Zanin, Fátima A. A.; Sampaio Moura, Marcelo; Heredia Seixas, Fábio; Rodrigues de Araujo Estrela, Cyntia; Estrela, Carlos; Djalma Pécora, Jesus

2003-06-01

273

Erosion and contamination of the surface of Vesta  

NASA Astrophysics Data System (ADS)

The data supplied by the Dawn mission revealed us that Vesta is a small world whose surface underwent a complex and violent evolution. Moreover, the ancient age of Vesta revealed by the HED (Howardite, Eucrite, Diogenite) meteorites indicates that Vesta crossed the whole history of the Solar System and suggests that its surface should have undergone an intense reprocessing due to the interplay of erosion, ejecta blanketing and contamination by exogenous material. Here we discuss how these processes could have affected the surface of Vesta during the different phases of the evolution of the Solar System.

Turrini, D.

2012-09-01

274

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.

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

275

Evidence that contaminated surfaces contribute to the transmission of hospital pathogens and an overview of strategies to address contaminated surfaces in hospital settings.  

PubMed

Evidence that contaminated surfaces contribute to the transmission of hospital pathogens comes from studies modeling transmission routes, microbiologic studies, observational epidemiologic studies, intervention studies, and outbreak reports. This review presents evidence that contaminated surfaces contribute to transmission and discusses the various strategies currently available to address environmental contamination in hospitals. PMID:23622751

Otter, Jonathan A; Yezli, Saber; Salkeld, James A G; French, Gary L

2013-05-01

276

Photosynthesis below the surface in a cryptic microbial mat  

NASA Astrophysics Data System (ADS)

The discovery of subsurface communities has encouraged speculation that such communities might be present on planetary bodies exposed to harsh surface conditions, including the early Earth. While the astrobiology community has focused on the deep subsurface, near-subsurface environments are unique in that they provide some protection while allowing partial access to photosynthetically active radiation. Previously we identified near-surface microbial communities based on photosynthesis. Here we assess the productivity of such an ecosystem by measuring in situ carbon fixation rates in an intertidal marine beach through a diurnal cycle, and find them surprisingly productive. Gross fixation along a transect (99×1 m) perpendicular to the shore was highly variable and depended on factors such as moisture and mat type, with a mean of ~41 mg C fixed m[minus sign]2 day[minus sign]1. In contrast, an adjacent well-established cyanobacterial mat dominated by Lyngbya aestuarii was ~12 times as productive (~500 mg C fixed m[minus sign]2 day[minus sign]1). Measurements made of the Lyngbya mat at several times per year revealed a correlation between total hours of daylight and gross daily production. From these data, annual gross fixation was estimated for the Lyngbya mat and yielded a value of ~1.3×105 g m[minus sign]2 yr[minus sign]1. An analysis of pulse-chase data obtained in the study in conjunction with published literature on similar ecosystems suggests that subsurface interstitial mats may be an overlooked endogenous source of organic carbon, mostly in the form of excreted fixed carbon.

Rothschild, Lynn J.; Giver, Lorraine J.

2002-10-01

277

Effect of organic contamination upon microbial distributions and heterotrophic uptake in a Cape Cod, Mass., aquifer.  

PubMed Central

Bacterial abundance, distribution, and heterotrophic uptake in a freshwater aquifer contaminated by treated sewage were determined from analyses of groundwater and sediment-core samples. The number of free-living (unattached) bacteria in contaminated groundwater declined steadily with increasing distance from the source of sewage infiltration, from 1.94 (+/- 0.20) X 10(6) ml-1 at 0.21 km to 0.25 (+/- 0.02) X 10(6) ml-1 at 0.97 km. Bacterial abundance in groundwater sampled at 0.31 km correlated strongly with specific conductance and increased sharply from 4.0 (+/- 0.3) X 10(4) ml-1 at a depth of 6 m to 1.58 (+/- 0.12) X 10(6) ml-1 at 14 m, then declined at 20 and 31 m to 1.29 (+/- 0.12) X 10(6) and 0.96 (+/- 0.12) X 10(6) ml-1, respectively. A majority of the bacteria in contaminated and uncontaminated zones of the aquifer were bound to the surfaces of particulates, less than 60 micron in diameter. The glucose uptake rate, assayed at in situ and 5 microM concentrations, declined steadily in contaminated groundwater sampled along a transect. A preparative wet-sieving technique for use in processing core samples for bacterial enumeration is described and evaluated. Images

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

1984-01-01

278

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

279

The selection of mixed microbial inocula in environmental biotechnology: example using petroleum contaminated tropical soils.  

PubMed

The impact of inorganic N and P additions on a tropical soil contaminated with petroleum hydrocarbons was investigated using molecular and culture techniques. Microcosms were incubated for 42 days and sampled at 0, 1, 7, 28 and 42 days. Changes in bacterial community structure were determined using denaturing gradient gel electrophoresis (DGGE) of the rRNA following reverse transcription PCR using primers specific to the V3 region of the 16S rRNA gene. To identify which components of the microbial community were changing during incubation, PCR amplicons were resolved using DGGE and the banding patterns analyzed using stepwise discriminant function analysis (SDA). SDA showed that the number of bands needed to recover the differences between samples over time could be reduced from the initial 11 bands for the 16S rRNA transcript to 3 bands. Sequences originating from the rRNA gels (16S rRNA transcripts) were recovered in clades containing known cultured isolates of Bacillus marisflavi, Microbacterium oxydans and Pseudomonas oleovorans. Isolation studies on these soils using lubricant oil as a carbon source yielded 317 bacterial isolates, 3 of which showed high sequence similarity (>96%) with the 16S rRNA transcripts identified using SDA as being important in differentiating between bacterial communities over time. These isolates were then tested singly and in combination for their ability to degrade lubricant oil. These analyses demonstrated that the consortium selected using the combined molecular-SDA approach was more effective at degrading the lubricant in both liquid media and in contaminated sand than the single isolates. PMID:16226327

Supaphol, Savaporn; Panichsakpatana, Supamard; Trakulnaleamsai, Savitr; Tungkananuruk, Nipon; Roughjanajirapa, Pinnapar; O'Donnell, Anthony Gerard

2005-10-12

280

Adsorption of spent fuel storage pool contaminants into metal surfaces  

SciTech Connect

Shipping casks, after being submerged in spent fuel pools for the purpose of loading or unloading fuel, resist complete removal of the adsorbed contamination. To systematically study the mechanisms involved, 122 metal surface samples were immersed in the spent fuel storage pool of the Callaway Power Plant for periods of 7 to 30 days. After being removed from the pool, all samples were washed and wiped (with cloth) using demineralized water. They were then gamma counted for absolute activity, by using Eu-152 as an energy efficiency calibrator, applied uniformly to unexposed sample surfaces. Swipes were taken after each of 3 days of such environmental conditioning. Following this conditioning, selected samples were again counted to determine absolute contamination remaining on the samples. 2 refs., 1 tab.

Reaves, K.; Kunze, J.; Lu, Kang (Missouri Univ., Columbia, MO (USA)); Bennett, P.C. (Sandia National Labs., Albuquerque, NM (USA))

1990-01-01

281

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

282

Biostimulation of the autochthonous microbial community for the depletion of polychlorinated biphenyls (PCBs) in contaminated sediments.  

PubMed

In this study, the effect of the biostimulation of the autochthonous microbial community on the depletion of polychlorinated biphenyls (PCBs) in historically contaminated sediments (6.260 ± 9.3 10(-3)??g PCB/ g dry weight) has been observed. Biostimulation consisted of (1) the amendment of an electron donor to favor the dehalogenation of the high-chlorinated PCBs and (2) the vegetation of sediments with Sparganium sp. plants to promote the oxidation of the low-chlorinated PCBs by rhizodegradation. The effects of the treatments have been analyzed in terms of both PCB depletion and changes of the autochthonous bacterial community structure. The relative abundance of selected bacterial groups with reference to untreated sediments has been evaluated by quantitative real-time PCR. The amendment of acetate determined the enrichment of anaerobic dechlorinators like Dehalococcoides sp. Vegetation with Sparganium sp. plants determined the enrichment of either (3) the dechlorinators, Dehalococcoides and the Chloroflexi o-17/DF-1 strains or (4) the Acidobacteria, ?-Proteobacteria, Actinobacteria, ?-Proteobacteria, Bacteroidetes, and Firmicutes. The combination of the two biostimulation strategy determined the 91.5 % of abatement of the initial PCB content. PMID:23208754

Di Gregorio, Simona; Azaizeh, Hassan; Lorenzi, Roberto

2012-12-04

283

Effects of petroleum contamination on soil microbial numbers, metabolic activity and urease activity.  

PubMed

The influence of petroleum contamination on soil microbial activities was investigated in 13 soil samples from sites around an injection water well (Iw-1, 2, 3, 4) (total petroleum hydrocarbons (TPH): 7.5-78 mg kg(-1)), an oil production well (Op-1, 2, 3, 4, 5) (TPH: 149-1110 mg kg(-1)), and an oil spill accident well (Os-1, 2, 3, 4) (TPH: 4500-34600 mg kg(-1)). The growth rate constant (?) of glucose stimulated organisms, determined by microcalorimetry, was higher in Iw soil samples than in Op and Os samples. Total cultivable bacteria and fungi and urease activity also decreased with increasing concentration of TPH. Total heat produced demonstrated that TPH at concentrations less than about 1 g kg(-1) soil stimulated anaerobic respiration. A positive correlation between TPH and soil organic matter (OM) and stimulation of fungi-bacteria-urease at low TPH doses suggested that TPH is bound to soil OM and slowly metabolized in Iw soils during OM consumption. These methods can be used to evaluate the potential of polluted soils to carry out self-bioremediation by metabolizing TPH. PMID:22336736

Guo, Huan; Yao, Jun; Cai, Minmin; Qian, Yiguang; Guo, Yue; Richnow, Hans H; Blake, Ruth E; Doni, Serena; Ceccanti, Brunello

2012-02-14

284

Effects of Microbial Metabolic Lag in Contaminant Transport and Biodegradation Modeling  

Microsoft Academic Search

A model is introduced for microbial kinetics in porous media that includes effects of transients in the metabolic activity of subsurface microorganisms. The model represents the microbial metabolic activity as a functional of the history of aqueous phase substrates; this dependence is represented as a temporally nonlocal convolution integral. Conceptually, this convolution represents the activity of a microbial component as

Brian D. Wood; Timothy R. Ginn; Clint N. Dawson

1995-01-01

285

Effects of microbial metabolic lag in contaminant transport and biodegradation modeling  

Microsoft Academic Search

A model is introduced for microbial kinetics in porous media that includes effects of transients in the metabolic activity of subsurface microorganisms. The model represents the microbial metabolic activity as a functional of the history of aqueous phase substrates; this dependence is presented as a temporally nonlocal convolution integral. Conceptually, this convolution represents the activity of a microbial component as

Brian D. Wood; Timothy R. Ginn; Clint N. Dawson

1995-01-01

286

Effects of microbial metabolic lag in contaminant transport and biodegradation modeling  

Microsoft Academic Search

A model is introduced for microbial kinetics in porous media that includes effects of transients in the metabolic activity of subsurface microorganisms. The model represents the microbial metabolic activity as a functional of the history of aqueous phase substrates; this dependence is represented as a temporally nonlocal convolution integral. Conceptually, this convolution represents the activity of a microbial component as

Brian D. Wood; Timothy R. Ginn; Clint N. Dawson

1995-01-01

287

Interaction of molecular contaminants with high-k dielectric surfaces  

NASA Astrophysics Data System (ADS)

As the device feature size shrinks, films of silicon oxide (SiO 2) will become unsuitable for MOSFET gate dielectric applications and have to be replaced by thicker films of a high-k dielectric material. Among the high-k materials, hafnium oxide (HfO2) and zirconium oxide (ZrO2) are the most promising candidates. Molecular contamination can affect the quality of the new gate dielectric films in a manner similar to ultrathin SiO2 films. Therefore, characterization of contaminant adsorption behavior of these high-k films should assist in deciding their potential for successful integration in silicon MOS technology. The interactions of moisture and organic (in particular IPA) contamination with ALCVD(TM) deposited 5-nm HfO2 and ZrO2 films were investigated using mass spectrometry. HfO2 and ZrO2 were found to have similar moisture adsorption loadings, but significantly higher than that of SiO2. The new high-k materials also retained a higher portion of the adsorbed moisture after an isothermal nitrogen purge. Almost all the adsorbed moisture could be removed from SiO2 and HfO2 after a 300°C bake under nitrogen purge, whereas ZrO 2 surfaces retained significant amounts of the adsorbed moisture. Experiments with ppb-levels of IPA showed that the adsorption loading on the three surfaces had the following order: ZrO2 > HfO2 > SiO2. The relatively slow desorption kinetics of H2O and IPA highlighted the difficulty in removal of these contaminants from HfO2 and ZrO 2 surfaces. Presence of pre-adsorbed moisture increased IPA adsorption on SiO2, but reduced adsorption on HfO2 and ZrO 2. Isotope labeling studies with D2O showed that IPA reacted with surface hydroxyl groups to form a chemisorbed alkoxy species on all oxides. A multilayer model for adsorption of water and IPA was developed to understand the mechanism of interactions of contaminants with these surfaces. Results indicated that ZrO2 formed the strongest surface-hydroxyl bond and also physisorbed IPA stronger than HfO2 and SiO2. The practical application of the adsorption model is also demonstrated. The results of this work should aid in the selection of the most appropriate dielectric film and design of process/equipment so that it can be more readily integrated into silicon technology.

Raghu, Prashant

288

Efficacy of dimethyl benzyl ammonium chloride and microbial contamination studies in a modern sugarcane milling unit in Thailand  

Microsoft Academic Search

The modern milling process at Mitr Phuveing Sugar factory takes less than 10 min from cane stalk to mixed juice stage before\\u000a the liming process. However, the microorganisms still affect sugar yield in the factory. The efficacy of dimethyl benzyl ammonium\\u000a chloride (DBAC) and microbial contamination in the sugar cane juice from milling process were studied. The inhibitory effect\\u000a of

N. Milintawisamai; C. Ngasan; R. Maungmontri; W. Buttapeng; R. Kotrsri; A. Pliansinchai; P. Weerathaworn

2009-01-01

289

Metabolic and phylogenetic analysis of microbial communities during phytoremediation of soil contaminated with weathered hydrocarbons and heavy metals  

Microsoft Academic Search

In the current study, the microbial ecology of weathered hydrocarbon and heavy metal contaminated soil undergoing phytoremediation\\u000a was studied. The relationship of functional diversity, measured as carbon source utilisation in Biolog plates and extracellular\\u000a enzymatic activities, and genetic diversity of bacteria was evaluated. Denaturing gradient gel electrophoresis was used for\\u000a community analyses at the species level. Bulk soil and rhizosphere

Marja R. T. Palmroth; Perttu E. P. Koskinen; Anna H. Kaksonen; Uwe Münster; John Pichtel; Jaakko A. Puhakka

2007-01-01

290

Soil microbial parameters and luminescent bacteria assays as indicators for in situ bioremediation of TNT-contaminated soils.  

PubMed

In situ bioremediation is increasingly being discussed as a useful strategy for cleaning up contaminated soils. Compared to established ex situ procedures, meaningful and reliable approaches for monitoring the remediation processes and their efficiency are of special importance. The subject of this study was the significance of two bioassays for monitoring purposes. The work was performed within the scope of a research project on the in situ bioremediation of topsoil contaminated with 2,4,6-trinitrotoluene (TNT). To evaluate changes within different experimental fields during a 17-month remediation period, the results of soil microbial assays and luminescent bacteria assays were compared with chemical monitoring data. The luminescent bacteria assays showed a significant reduction of the water-soluble soil toxicants in the treated fields. This bioassay proved to be a sensitive screening indicator of toxicity and may effectively aid the ecotoxicological interpretation of chemical monitoring data. Microbial biomass (C(mic)), the metabolic quotient (qCO2), and the ratio of microbial to organic carbon (C(mic)/C(org)) showed a highly significant correlation with total concentrations of TNT in the soil. But, in contrast to luminescent bacteria assays, this approach did not reveal any recovery of the soil at the end of the remediation period. There is clear evidence for persistent adverse effects of chronic TNT contamination on the site-specific microbial community and the local carbon cycle in the soil. The study clearly exhibits the differences between, as well as the complementary value of both bioassay approaches for monitoring short-term and long-term effects of soil contamination and the efficiency of remediation. PMID:12656263

Frische, Tobias; Höper, Heinrich

2003-01-01

291

Effects of Gamma-Irradiation on Microbial Contamination and on Histological Changes of Muscle in Poecilia reticulata  

Microsoft Academic Search

This study describes the effect of gamma-irradiation on the microbial skin and organ contamination and on the histological changes of fish skeletal musculature. The aquarium fish Poecilia reticulata were exposed to the radiation effect of 60Co at the doses of 20 and 30 Gy (11.36 Gy\\/min). Frequent intravital haemorrhages were observed from day 8 after the exposure. A general long-term

Katarína Be?ová; Petr Dvo?ák; Miloš Halán; Zuzana Kaleni?ová; Hedviga Sehnálková; Viera Cigánková

2009-01-01

292

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.

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

293

Effects of Diffusion Pump Oil Contamination on the Reflectance Characteristics of Various Surfaces.  

National Technical Information Service (NTIS)

During thermal testing in a space simulation chamber, the extent of diffusion pump oil contamination on all important surfaces should be determined. This information and an understanding of the reflectance characteristics of the oil contaminated surfaces ...

E. C. Pinion

1966-01-01

294

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

Microsoft Academic Search

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

Eric Smit; Paula Leeflang; Karel Wernars

1997-01-01

295

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

296

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.

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

2013-01-01

297

Water sources and their protection from the impact of microbial contamination in rural areas of Beijing, China.  

PubMed

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

2013-03-05

298

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

299

Versatile microbial surface-display for environmental remediation and biofuels production  

SciTech Connect

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

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

2008-02-14

300

Influence of microbial transport processes on in-situ biodegradation of ground-water contaminants. Technical progress report (Final)  

SciTech Connect

A fundamental understanding of both transport and transformation processes is essential to the development of technically sound remediation strategies for groundwater contamination. Accordingly, the goal of the project is to enhance the rate and efficiency of in situ microbial degradation of subsurface contaminants through an improved understanding of processes which govern transport, attachment, growth and activity of microorganisms in porous media. The report is organized into the following sections: Transport Processes: contains experimental methods and results which document the effect of biofilm accumulation on the transport of water, nutrients and suspended cells in one-dimensional porous media flow reactions (objective 1); Effects of Cell Starvation and Motility: presents experimental procedures and results describing transport characteristics of starved vs. growing and motile vs. nonmotile cells in porous media (objective 2); Modeling Microbial Transport and Activity: describes development of a mathematical model which simulates contaminant biodegradation/biosorption, nutrient depletion and biomass accumulation in one-dimensional porous media flow (objective 3); Bioremediation Guidelines: summarizes relevant information in the form of guidelines useful to decision makers concerned with bioremediation of contaminated water and soil (objective 4).

Cunningham, A.B.; Characklis, W.G.

1991-01-01

301

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

302

Reducing microbial contamination in storm runoff from high use areas on California coastal dairies.  

PubMed

High use areas are a fundamental part of California coastal dairies and grazing livestock ranches as feeding areas, nurseries, and sick pens. High stocking densities and daily use in these areas lead to soil surfaces devoid of vegetation and covered in manure, with high potential for manure transport during winter rains to receiving waters regulated for shellfish harvesting and recreation. We characterized the association between California's Mediterranean climate and a series of existing and proposed management practices on fecal coliform bacteria (FCB) transport from high use areas on dairies and ranches. Results from 351 storm runoff samples collected below 35 high-use areas indicate that removal of cattle during winter, locating high use areas on level ground, application of straw and seeding, and vegetative buffer strip implementation were significantly associated with FCB concentration and load reductions. These results complement our findings for reductions of specific pathogens in runoff from these areas. These findings have practical significance because they document surface water quality benefits that the studied management practices provide in application on working farms and ranches. This direction is critical and timely for on-farm management efforts seeking to reduce microbial pollution in runoff and comply with indicator bacteria water quality criteria. PMID:19809136

Lewis, D J; Atwill, E R; Lennox, M S; Pereira, M D G; Miller, W A; Conrad, P A; Tate, K W

2009-01-01

303

Production of microbial surfactants from oily sludge-contaminated soil by Bacillus subtilis DSVP23.  

PubMed

The indigenous microbial community utilizing aliphatic, aromatic, and polar components from the oily sludge as sole source of carbon and energy was selected from the soil samples of Ankleshwar, India for biosurfactant production. Evaluation of biosurfactant production was done using screening assays such as surface tension reduction, hemolytic activity, emulsification activity, drop-collapse assay, and cell surface hydrophobicity studies. Maximum biosurfactant (6.9 g/l) production was achieved after 5 days of growth from Bacillus subtilis DSVP23 which was identified by 16S RNA technique (NCBI GenBank accession no. EU679368). Composition of biosurfactant showed it to be lipopeptide in nature with 15.2% protein content and 18.0% lipid content. Functional group analysis was also done by using Fourier transform infrared spectroscopy which showed it to be a protein-bound lipid thereby imparting them special properties. Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometric and nuclear magnetic resonance revealed that the major constituents of lipopeptide are leucine and isoleucine. Gas chromatographic analysis data indicated that oily sludge components of chain length C??-C?? and aromatic hydrocarbons were degraded effectively by B. subtilis DSVP23 after 5 days of incubation. These results collectively points toward the importance of B. subtilis DSVP23 as a potential candidate for bioremediation studies. PMID:22391691

Pemmaraju, Suma C; Sharma, Deepak; Singh, Nivedita; Panwar, Richa; Cameotra, Swaranjit S; Pruthi, Vikas

2012-03-04

304

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

305

Shedding of foodborne pathogens and microbial carcass contamination of hunted wild ruminants.  

PubMed

To assess the shedding of selected bacterial foodborne pathogens, fecal samples from 239 hunted wild red deer, roe deer, chamois, and ibex were examined. All samples tested negative for Salmonella spp. and L. monocytogenes, but other Listeria species were occasionally found. Of the 239 fecal samples, 32.6% tested positive for stx (Shiga toxins), 6.7% for eae (intimin) and 13.8% for both stx and eae genes. Among the 56 isolated Shiga toxin-producing Escherichia coli (STEC) strains, 44.6% harbored genes for the Stx2 group, 30.4% for the Stx1 group, and 21.4% for both Stx1 and Stx2. Only two of these strains harbored eae. Hence, wild ruminants constitute a reservoir for STEC, but further characterization data of the isolated strains are required to assess their actual human pathogenicity. In addition, 328 carcasses from hunted wild red deer, roe deer, and chamois were examined for total viable counts (TVC) and Enterobacteriaceae by swabbing. For the examined animal species, average TVC (4.0-4.2 log CFU cm(-2)) and average Enterobacteriaceae counts/detection rates (2.3-2.6 log CFU cm(-2); 87.5-90%) were at comparable levels. On the other hand, the microbial status of carcasses differed between certain abattoirs by several orders of magnitude. Strict compliance with good hunting and hygiene practices during any step from shooting, through evisceration in the field, to dehiding, cooling, and processing is therefore of central importance to avoid contaminations and to prevent foodborne pathogens carried by the animals from entering the food chain. PMID:22503394

Obwegeser, Tobias; Stephan, Roger; Hofer, Eveline; Zweifel, Claudio

2012-03-26

306

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.

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

1998-01-01

307

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.

Yagi, Jane M.; Madsen, Eugene L.

2009-01-01

308

Early warning system for detection of microbial contamination of source waters  

Microsoft Academic Search

Ensuring chemical and microbial water quality is an ever increasing important issue world-wide. Currently, determination of microbial water quality is a time (and money) consuming manual laboratory process. We have developed and field-tested an online and real-time sensor for measuring the microbial water quality of a wide range of source waters. The novel optical technique, in combination with advanced data

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

2011-01-01

309

Microbial quality of rainwater supplies in developed countries: a review  

Microsoft Academic Search

The current paper examines the reported microbial quality of rainwater supplies. The majority of microbial contamination derives from debris and faecal material deposited on the roof surface, principally from birds. The prevalence and level of contamination varies widely, both in terms of indicator organisms and pathogens. Gastrointestinal pathogens such as Campylobacter spp., Salmonella spp., Cryptosporidium spp. and Giardia spp. have

L. Fewtrell; D. Kay

2007-01-01

310

Measurement of total hemispherical emissivity of contaminated mirror surfaces  

NASA Astrophysics Data System (ADS)

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

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

311

Effect of some metal salts on the cultivable part of soil microbial assemblage in a calcareous loam cropland 6 years after contamination  

Microsoft Academic Search

Heavy metal contamination is of great interest because of the accumulation in soil and a potential risk to get into the food chain. Effect of three heavy metal salts added to field plots on the soil microbial assemblage and their total biomass was investigated 6 years after the artificial contamination. The metal addition was 90 and 810 kg per hectare

Tibor Szili-Kovács

312

Selected chemical contaminants in surface sediments of Commencement Bay and the Tacoma waterways, Washington, USA (revised)  

Microsoft Academic Search

Eight metals, 21 organic priority pollutants, and 11 other contaminants and contaminant-related sediment characteristics were measured in surface sediments (upper 2 cm) at 21 locations in Commencement Bay and the Tacoma Waterways, Washington. Summary statistics were calculated and statistical approaches were applied to subsets of the data to classify sediment contamination. High concentrations of some contaminants appeared to be related

D. W. Schults; S. P. Ferraro; G. R. Ditsworth; K. A. Sercu

1987-01-01

313

Microbial Monitoring of Common Opportunistic Pathogens by Comparing Multiple Real-Time PCR Platforms for Potential Space Applications.  

National Technical Information Service (NTIS)

Because the International Space Station is a closed environment with rotations of astronauts and equipment that each introduce their own microbial flora, it is necessary to monitor the air, surfaces, and water for microbial contamination. Current microbia...

A. Singhal A. S. Johnston C. M. Ott C. M. Oubre D. X. Jett K. J. Venkateswaran K. U. Jones M. C. Roman M. N. Birmele M. S. Roberts P. A. Vaishampayan T. A. Ozbolt V. A. Castro

2013-01-01

314

Effect of pyrene contamination on soil microbial biomass and community structure using PLFA analysis  

Microsoft Academic Search

Phospholipid fatty acid (PLFA) can be used as biological marker of microbial biomass and community structure. In this study PLFA analysis wasused on soil microbial diversity with pyrene added. The results showed that in the short term, low concentrations of pyrene had no significant effect on Bac-PLFA and Fun-PLFA, while high concentration pyrene showed inhibition effect. It also revealed that

Jie Liu; Xiawei Peng; Zhihui Bai

2011-01-01

315

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

PubMed

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

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

2011-06-01

316

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

317

Laser-ion acceleration through controlled surface contamination  

NASA Astrophysics Data System (ADS)

Ion acceleration from interaction of intense laser pulses with solid targets was dominated by protons. This phenomenon is attributed to the presence of protons in the water and hydrocarbon residue on the target surface. Substitution of the contaminant layer on the target surface with a desired species can lead to selection of accelerated ion species and enhancement of acceleration. With a focal intensity of ˜4x10^18W/cm^2 at 0.5 kHz repetition rate, deuterons up to 75 keV are accelerated from a glass target simply by placing 1 mL of heavy water inside the experimental chamber prior to vacuum-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 three to five while increasing the maximum energy of the generated deuterons to 140 keV. This technique was further developed by other researchers; the solid target is cryogenic-cooled to produce an ice layer of heavy water for deuteron acceleration.

Hou, Bixue; He, Zhaohan; Nees, John; Petrov, George; Davis, Jack; Thomas, Alexander; Krushelnick, Karl

2012-10-01

318

The Borexino Solar Neutrino Experiment: Scintillator purification and surface contamination  

NASA Astrophysics Data System (ADS)

The Borexino Solar Neutrino Experiment will observe the monoenergetic (862 keV) 7Be neutrinos, produced in the solar reaction 7Be+e- ?7 Li+nue. These neutrinos are the second most abundant species of solar neutrinos, with an expected flux at earth of 5 x 109/cm2/s. Using nu - e scattering in an aromatic liquid scintillator, Borexino will make the first real time measurement of the solar neutrino flux at energies less than 1 MeV. In addition to checking Standard Solar Model and neutrino oscillation predictions at low energies, Borexino will test the MSW vacuum-matter transition, luminosity constraint, and non-standard theories such as mass varying neutrinos. The Borexino detector will also be sensitive to supernova neutrinos, geoneutrinos, reactor neutrinos, and pep solar neutrinos. The pep measurement will tightly constrain the primary pp solar neutrino flux whose energy is below the Borexino threshold. With an expected rate of 35 events per day from solar 7Be neutrinos, the maximum tolerable background rate is one count per day. Removal of radioactive isotopes from the liquid scintillator is essential for the experiment's success and will be achieved with purification techniques including filtration, distillation, water extraction, nitrogen stripping, and silica gel adsorption. Results from small-scale purification efficiency tests are presented. Water extraction showed moderate but inadequate removal of 210Po which is a dominant background. Distillation reduced 210Po by a factor of more than 500. Online purification involves cycling over 300 m3 of scintillator from the detector though the purification plants. Flow patterns within the detector that influence the purification efficiency were determined with numerical simulations. Poor flow in the prototype Counting Test Facility showed effectively stagnant volumes within the detector. These are not present in the larger Borexino detector. Surface contamination in Borexino arises primarily from contact with contaminated liquids and the deposition of airborne radon progeny. Measurements of desorption rates showed that surface contaminants are transferred to the scintillator logarithmically with time. Partitioning constants between the scintillator and surfaces were measured and airborne deposition rate of radon progeny in a clean room environment are analyzed. The efficiency of various surface cleaning techniques was also tested.

Leung, Michael

319

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.

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

2000-01-01

320

[Microbial contamination of water by pipe and hose material. 1. Detection of colony count changes].  

PubMed

Materials may produce a growth of microorganisms by contact with water. Pipes and hoses with a narrow diameter have not yet been tested on their influence on the microbial colonization of the water. A harmful change has been discussed especially in dental treatment units. Pipes and hoses were tested in their influence on the microbial growth for half a year. Glass, high grade steel, copper and PTFE showed no increase in microorganisms or only a little in the beginning. The other tested materials, PVC, PE, PA, silicon and rubber, produced an intensive microbial growth. PMID:3138830

Schoenen, D; Wehse, A

1988-05-01

321

Selected Chemical Contaminants in Surface Sediments of Commencement Bay and the Tacoma Waterways, Washington, USA (Revised).  

National Technical Information Service (NTIS)

Eight metals, 21 organic priority pollutants, and 11 other contaminants and contaminant-related sediment characteristics were measured in surface sediments (upper 2 cm) at 21 locations in Commencement Bay and the Tacoma Waterways, Washington. Summary stat...

D. W. Schults S. P. Ferraro G. R. Ditsworth K. A. Sercu

1987-01-01

322

SELECTED CHEMICAL CONTAMINANTS IN SURFACE SEDIMENTS OF COMMENCEMENT BAY AND THE TACOMA WATERWAYS, WASHINGTON, USA (REVISED)  

EPA Science Inventory

Eight metals, 21 organic priority pollutants, and 11 other contaminants and contaminant-related sediment characteristics were measured in surface sediments (upper 2 cm) at 21 locations in Commencement Bay and the Tacoma Waterways, Washington. Summary statistics were calculated an...

323

Effect of biostimulation on the microbial community in PCB-contaminated sediments through periodic amendment of sediment with iron.  

PubMed

Reductive dehalogenation of polychlorinated biphenyls (PCBs) by indigenous dehalorespiring microorganisms in contaminated sediments may be enhanced via biostimulation by supplying hydrogen generated through the anaerobic corrosion of elemental iron added to the sediment. In this study, the effect of periodic amendment of sediment with various dosages of iron on the microbial community present in sediment was investigated using phospholipid fatty acid analysis (PLFA) over a period of 18 months. Three PCB-contaminated sediments (two freshwater lake sediments and one marine sediment) were used. Signature biomarker analysis of the microbial community present in all three sediments revealed the enrichment of Dehalococcoides species, the population of which was sustained for a longer period of time when the sediment microcosms were amended with the lower dosage of iron (0.01 g iron per g dry sediment) every 6 months as compared to the blank system (without iron). Lower microbial stress levels were reported for the system periodically amended with 0.01 g of iron per g dry sediment every 6 months, thus reducing the competition from other hydrogen-utilizing microorganisms like methanogens, iron reducers, and sulfate reducers. The concentration of hydrogen in the system was found to be an important factor influencing the shift in microbial communities in all sediments with time. Periodic amendment of sediment with larger dosages of iron every 3 months resulted in the early prevalence of Geobacteraceae and sulfate-reducing bacteria followed by methanogens. An average pH of 8.4 (range of 8.2-8.6) and an average hydrogen concentration of 0.75% (range of 0.3-1.2%) observed between 6 and 15 months of the study were found to be conducive to sustaining the population of Dehalococcoides species in the three sediments amended with 0.01 g iron per g dry sediment. Biostimulation of indigenous PCB dechlorinators by the periodic amendment of contaminated sediments with low dosages of iron metal may therefore be an effective technology for remediation of PCB-contaminated sediments. PMID:21528414

Srinivasa Varadhan, A; Khodadoust, Amid P; Brenner, Richard C

2011-04-29

324

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

325

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

326

EFFECTS OF ORGANIC AMENDMENTS ON MICROBIAL PROPERTIES IN LEAD-CONTAMINATED SOILS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Environmental Protection Agency lists more than 17,000 contaminated sites in the United States, many of which are contaminated with heavy metals including lead (Pb) and zinc (Zn). Lead contamination in soil has been shown to be a threat to human health and ecosystem functioning through adverse e...

327

MULTIPLE IMAGING TECHNIQUES DEMONSTRATE THE MANIPULATION OF SURFACES TO REDUCE BACTERIAL CONTAMINATION AND CORROSION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Surface imaging techniques are 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. The complementarity...

328

FTIR Study on Molecular Contamination on Surface of Optical Materials  

NASA Astrophysics Data System (ADS)

The IR spectra of the molecular contaminants on surface of optical materials were measured. The optical disks used were SiO2, BK7 (SiO2 70%, B2O3 10%, K2O 8%, N2O 8%), CaF2, ZnSe and Al2O3. N2, O2, H2O, and CO2 were adopted as contamination gases. IR spectra of H2O (2.7kPa) on BK7 at 373K showed two absorption bands (OH stretching vibration: around 4000cm-1-3500cm-1 and OH bending vibration: around 2000cm-1-1500cm-1). The absorption intensity decreased with a decrease in temperature and a new band (around 3250cm-1) appeared at 173K. The new band was attributed to phase transition of H2O. These phenomena were also observed on the other three discs, except for SiO2. IR spectra of SiO2 showed OH stretching band (3676cm-1). The absorption intensity decreased with a decrease in temperature. But two new bands (3720cm-1 and 3620cm-1) appeared under an atmosphere of N2 (66.5kPa), O2 (66.5kPa), H2O (2.7kPa) or CO2 (0.7 or 13.3kPa). A similar phenomenon was also observed for BK7, which has OH group. These results suggested the functional group of SiOH interacted with contamination molecules.

Katoh, Masahiro; Okano, Nobuaki; Horikawa, Toshihide; Tomida, Tahei; Itoh, Nobunari

329

Modeling Microbial Growth Dynamics, Patterns, and Coexistence on Partially Saturated Rough Surfaces  

NASA Astrophysics Data System (ADS)

A new modeling tool was developed to study the impact of variations in matric potential on aquatic pathways and substrate diffusion, and on microbial growth and movement on unsaturated rough surfaces. The modeling domain is composed of prescribed distributions of conical pits (sites) connected by prismatic channels (bonds) representing rough surfaces of soils or rocks. The well-defined geometry facilitates exact description of aqueous phase distribution within the roughness for a given matric potential. Microbial growth within the resulting highly variable diffusion network architectures (vary with matric potential) and interactions with nutrient diffusion patterns are simulated by coupling Reaction-Diffusion Method (RDM) and the Active Walker Method (AWM). Simulation results show direct impact of wetness conditions (matric potential values) on microbial growth rates and expansion patters for the same surface roughness. In addition to modification of mean diffusion rates for drier or wetter conditions, the network connectivity may induce significant changes in spatial patters of microbial growth. Impact of these changes on coexistence of two competing microbial species will be discussed.

Long, T.; Or, D.

2005-12-01

330

Dynamical enhanced electron emission and discharges at contaminated surfaces  

NASA Astrophysics Data System (ADS)

Broad-area electrodes show electron emission already at electric field strengths F?107 V/m. This enhanced field emission (EFE) occurs only for contaminated surfaces. EFE is accompanied by photon emission and gas desorption yielding finally discharges. EFE is caused by dust and contaminants initiating the following effects: an electron is stochastically emitted in a trigger zone the electron gains energy ?E?e?xF * which excites electronic states which relax by the emission of electrons, photons, and atoms where the positive charges left behind enhance F *= ?F (??1) initiating so an electron avalanche, i.e., a high conductivity channel. Because of charge migration and neutralization, this avalanche has a life time. This pulsating EFE is accompanied by light emission and gas desorption yielding finally a gas cloud and a discharge. The pulsating, self-sustained EFE has the same root as: the enhanced secondary emission found first by Malter the conductivity switching exhibited by thin (? 1 ?m) layers of semiconductors or insulators the normal cathode fall and the firing-wave instability in neurodynamics.

Halbritter, J.

1986-01-01

331

Short-term microbial release during rain events from on-site sewers and cattle in a surface water source.  

PubMed

The protection of drinking water from pathogens such as Cryptosporidium and Giardia requires an understanding of the short-term microbial release from faecal contamination sources in the catchment. Flow-weighted samples were collected during two rainfall events in a stream draining an area with on-site sewers and during two rainfall events in surface runoff from a bovine cattle pasture. Samples were analysed for human (BacH) and ruminant (BacR) Bacteroidales genetic markers through quantitative polymerase chain reaction (qPCR) and for sorbitol-fermenting bifidobacteria through culturing as a complement to traditional faecal indicator bacteria, somatic coliphages and the parasitic protozoa Cryptosporidium spp. and Giardia spp. analysed by standard methods. Significant positive correlations were observed between BacH, Escherichia coli, intestinal enterococci, sulphite-reducing Clostridia, turbidity, conductivity and UV254 in the stream contaminated by on-site sewers. For the cattle pasture, no correlation was found between any of the genetic markers and the other parameters. Although parasitic protozoa were not detected, the analysis for genetic markers provided baseline data on the short-term faecal contamination due to these potential sources of parasites. Background levels of BacH and BacR makers in soil emphasise the need to including soil reference samples in qPCR-based analyses for Bacteroidales genetic markers. PMID:23981872

Aström, Johan; Pettersson, Thomas J R; Reischer, Georg H; Hermansson, Malte

2013-09-01

332

MOLECULAR TRACKING FECAL CONTAMINATION IN SURFACE WATERS: 16S RDNA VERSUS METAGENOMICS APPROACHES  

EPA Science Inventory

Microbial source tracking methods need to be sensitive and exhibit temporal and geographic stability in order to provide meaningful data in field studies. The objective of this study was to use a combination of PCR-based methods to track cow fecal contamination in two watersheds....

333

Hydride Compressor Sorption Cooler and Surface Contamination Issues  

NASA Astrophysics Data System (ADS)

A continuous-duty hydrogen sorption cryocooler is being developed for the Planck spacecraft, a mission to map the cosmic microwave background beginning in 2007. This cryocooler uses six individual compressor elements (CEs) filled with the hydriding alloy LaNi4.78Sn0.22 to provide high-pressure (50 bar) hydrogen to a Joule-Thomson (J-T) expander and to absorb low-pressure (~0.3 bar) gas from liquid hydrogen reservoirs cooled to ~18K. Quadrupole Mass Spectrometry (QMS) showed methane in these hydride beds after cycling during initial operation of laboratory tests of the Planck engineering breadboard (EBB) cooler. These contaminants have caused problems involving plugged J-T expanders. The contaminants probably come from reactions with residual hydrocarbon species on surfaces inside the hydride bed. The hydride bed in each CE is contained in an annular volume called a ``gas-gap heat switch,'' which serves as a reversible, intermittent thermal path to the spacecraft radiator. The gas-gap is either ``off'' (i.e., its pressure <1.3 Pa), or ``on'' (i.e., hydrogen gas at ~4 kPa). The hydrogen pressure is varied with an independent hydride actuator containing ZrNiHx. Early EBB cooler tests showed increasing parasitic heat losses from the inner beds, suggesting residual pressures in the gas gap during its ``off'' state. The pressure was shown to be due to hydrogen from outgassing from metallic surfaces in the gas gap and hydrogen permeation through the inner sorbent bed wall. This gas accumulation has serious end-of-life implications, as the ZrNi actuator has limited storage capacity and any excess hydrogen would necessarily affect its operation. This paper summarizes experiments on the behavior of hydrogen in the gas gap switch and formation of methane in the CE sorbent beds.

Bowman, R. C.; Reiter, J. W.; Prina, M.; Kulleck, J. G.; Lanford, W. A.

2003-07-01

334

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

2013-08-22

335

Vertically averaged contaminant transport with the streamline method in near-surface aquifers  

Microsoft Academic Search

Contaminant transport modeling is an important tool for assessing the impact of pollution in the subsurface. Transport modeling in unconfined shallow aquifers is particularly important because of aquifer susceptibility to contamination and direct linkage to surface water bodies. Such ''near-surface'' aquifers are often characterized by transience, sensitivity to recharge, and sensitivity to surface water behavior. Such aquifers are also often

J. R. Craig; A. J. Rabideau

2003-01-01

336

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

337

Bioremediation of the tobacco waste-contaminated soil by Pseudomonas sp. HF-1: nicotine degradation and microbial community analysis.  

PubMed

The highly effective nicotine-degrading bacterium Pseudomonas sp. HF-1 was augmented into the tobacco waste-contaminated soil to degrade nicotine and evaluate the effect of the bioremediation. Comparing with non-adding (NA) systems, the treatments with addition of strain HF-1 (TA) exhibited considerably stronger pollution disposal abilities and higher stability of pH value and moisture content, especially in groups containing a large quantity of tobacco waste. The denaturing gradient gel electrophoresis (DGGE) profiles showed that the Shannon-Wiener index decreased with increasing wastes in the NA treatments, while a gradual increase was found in the TA groups. A comparison of sequences from DGGE bands demonstrated that there were differences in the dominant microbial species between the two treatments, suggesting that strain HF-1 could persist in the soil and enhance the efficiency of tobacco waste disposal. The results of real-time fluorescence quantitative PCR (RT-qPCR) also indicated that strain HF-1 existed in the TA systems and grew with relative high quantities. In conclusion, the nicotine-degrading strain HF-1 played a leading role in the bioremediation of the tobacco waste-contaminated soil and influenced the dynamics and structure of the microbial community. PMID:23053086

Wang, Xin; Tang, Lu; Yao, Yanlai; Wang, Haixia; Min, Hang; Lu, Zhenmei

2012-09-29

338

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

339

Expanding applications for surface-contaminant sensing using the laser interrogation of surface agents (LISA) technique  

NASA Astrophysics Data System (ADS)

Laser Interrogation of Surface Agents (LISA) is a UV-Raman technique that provides short-range standoff detection and identification of surface-deposited chemical agents. ITT Industries, Advanced Engineering and Sciences Division, is currently developing and expanding the LISA technology under several programs that span a variety of missions for homeland defense. We will present and discuss some of these applications, while putting in perspective the overall evolution undergone by the technique within the last years. These applications include LISA-Recon (now called the Joint Contaminated Surface Detector--JCSD) which was developed under a cost-sharing arrangement with the U.S. Army Soldier and Biological Chemical Command (SBCCOM) for incorporation on the Army"s future reconnaissance vehicles, and designed to demonstrate single-shot on-the-move measurements of chemical contaminants at concentration levels below the Army"s requirements. In parallel, LISA-Shipboard is being developed to optimize the sensor technique for detection of surface contaminants in the operational environment of a ship. The most recently started activity is LISA-Inspector that is being developed to provide a transportable sensor in a ‘cart-like" configuration.

Ponsardin, Patrick L.; Higdon, N. S.; Chyba, Thomas H.; Armstrong, Wayne T.; Sedlacek, Arthur J., III; Christesen, Steven D.; Wong, Anna

340

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

Microsoft Academic Search

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

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

2005-01-01

341

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.

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

1984-01-01

342

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

343

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

344

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

345

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.

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

346

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

347

EFFECT OF IMPACT STRESS ON MICROBIAL RECOVERY ON AN AGAR SURFACE  

EPA Science Inventory

Microbial stress due to the impaction of microorganisms onto an agar collection surface was studied experimentally. he relative recovery rates of aerosolized Pseudomonas fluorescens and Micrococcus luteus were determined as a function of the impaction velocity by using a moving a...

348

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 ...

349

Analysis of different approaches for evaluation of surface energy of microbial cells by contact angle goniometry.  

PubMed

Microbial adhesion on solid substrate is important in various fields of science. Mineral-microbe interactions alter the surface chemistry of the minerals and the adhesion of the bacterial cells to mineral surface is a prerequisite in several biobeneficiation processes. Apart from the surface charge and hydrophobic or hydrophilic character of the bacterial cells, the surface energy is a very important parameter influencing their adhesion on solid surfaces. There were many thermodynamic approaches in the literature to evaluate the cells surface energy. Although contact angle measurements with different liquids with known surface tension forms the basis in the calculation of the value of surface energy of solids, the results are different depending on the approach followed. In the present study, the surface energy of 140 bacterial and seven yeast cell surfaces has been studied following Fowkes, Equation of state, Geometric mean and Lifshitz-van der Waals acid-base (LW-AB) approaches. Two independent issues were addressed separately in our analysis. At first, the surface energy and the different components of the surface energy for microbial cells surface are examined. Secondly, the different approaches are evaluated for their internal consistency, similarities and dissimilarities. The Lifshitz-van der Waals component of surface energy for most of the microbial cells is realised to be approximately 40 mJ/m2 +/-10%. Equation of state and Geometric mean approaches do not possess any internal consistency and yield different results. The internal consistency of the LW-AB approach could be checked only by varying the apolar liquid and it evaluates coherent surface energy parameters by doing so. The electron-donor surface energy component remains exactly the same with the change of apolar liquid. This parameter could differentiate between the Gram-positive and Gram-negative bacterial cells. Gram-negative bacterial cells having higher electron-donor parameter had lower nitrogen, oxygen and phosphorous content on their cell surfaces. Among the four approaches, LW-AB was found to give the most consistent results. This approach provides more detailed information about the microbial cell surface and the electron-donor parameter differentiates different type of cell surfaces. PMID:12206199

Sharma, P K; Rao, K Hanumantha

2002-08-01

350

Effects of microbial metabolic lag in contaminant transport and biodegradation modeling  

SciTech Connect

A model is introduced for microbial kinetics in porous media that includes effects of transients in the metabolic activity of subsurface microorganisms. The model represents the microbial metabolic activity as a functional of the history of aqueous phase substrates; this dependence is represented as a temporally nonlocal convolution integral. Conceptually, this convolution represents the activity of a microbial component as a fraction of its maximum activity, and it is conventionally known as the metabolic potential. The metabolic potential is used to scale the kinetic expressions to account for the metabolic state of the organisms and allows the representation of delayed response in the microbial kinetic equations. Calculation of the convolution requires the definition of a memory (or kernel) function that upon integration over the substrate history represents the microbial metabolic response. A simple piecewise-linear metabolic potential functional is developed here; however, the approach can be generalized to fit the observed behavior of specific systems of interest. The convolution that results form the general from of this model is nonlinear; these nonlinearities are handled by using two separate memory functions and by scaling the domains of the convolution integrals. The model is applied to describe the aerobic degradation of benzene in saturated porous media. Comparative simulations show that metabolic lag can be used to consistently describe observations and that a convolution form can effectively represent microbial lag for this system. Simulations also show that disregarding metabolic lag when it exists can lead to overestimation of the amount of substrate degraded. 45 refs., 4 figs., 1 tab.

Wood, B.D.; Ginn, T.R. [Pacific Northwest Laboratory, Richland, WA (United States); Dawson, C.N. [Rice Univ., Houston, TX (United States)

1995-03-01

351

Keeping in Touch: Microbial Life on Soil Particle Surfaces  

Microsoft Academic Search

Microorganisms in unsaturated soil live in a world dominated by the presence of extensive surfaces, both solid and gas–liquid interfacial surfaces. Particle attachment in soils is similar to particle attachment in aquatic systems, which, because of the high abundance of suspended populations has been widely studied. Although there seems to be a general advantage to the microbes living at the

Aaron L Mills

2003-01-01

352

High Resolution CryoFESEM of Microbial Surfaces  

NASA Astrophysics Data System (ADS)

The outer surfaces of three microorganisms, Giardia lamblia, Enterococcus faecalis, and Proteus mirabilis, were investigated by cryo-immobilization followed by sublimation of extracellular ice and cryocoating with either Pt alone or Pt plus carbon. Cryocoated samples were examined at [minus sign]125°C in either an in-lens field emission SEM or a below-the-lens field emission SEM. Cryocoating with Pt alone was sufficient for low magnification observation, but attempts to do high-resolution imaging resulted in radiolysis and cracking of the specimen surface. Double coating with Pt and carbon, in combination with high resolution backscatter electron detectors, enabled high-resolution imaging of the glycocalyx of bacteria, revealing a sponge-like network over the surface. High resolution examination of bacterial flagella also revealed a periodic substructure. Common artifacts included radiolysis leading to “cracking” of the surface, and insufficient deposition of Pt resulting in the absence of detectable surface topography.

Erlandsen, Stanley; Lei, Ming; Martin-Lacave, Ines; Dunny, Gary; Wells, Carol

2003-08-01

353

Microbial formation of volatile arsenic in cattle dip site soils contaminated with arsenic and DDT  

Microsoft Academic Search

This study was conducted to assess whether the addition of exogenous nutrients and bioaugmentation by arsenic (As) methylating fungi could accelerate the rate of As volatilisation in cattle dip soils containing mixed As and DDT contamination. Increasing levels of manure application resulted in a greater loss of As from contaminated soils [30% (w\\/w) > 15% (w\\/w) > 5% (w\\/w) manure].

B. B Edvantoro; R Naidu; M Megharaj; G Merrington; I Singleton

2004-01-01

354

Efficacy of simple hand-washing in reduction of microbial hand contamination of Iranian food handlers  

Microsoft Academic Search

Foods are likely to be faecally contaminated during preparation or dissemination by the Iranian Muslim food handler that their religion enjoins the mechanical cleaning of themselves after defecation. The current study was designed to determine the actual rate of hand contamination of Iranian food handlers with pathogenic flora of faeces or nose and to evaluate the efficacy of simple hand-washing

Hasan Shojaei; Jafar Shooshtaripoor; Masoud Amiri

2006-01-01

355

Peroperative microbial contamination of anterior chamber aspirates during extracapsular cataract extraction and phacoemulsification  

Microsoft Academic Search

BACKGROUNDThe normal conjunctival flora is one of the main sources of intraocular contamination during cataract surgery. The theory that the positive anterior chamber (AC) pressure during phacoemulsification (phaco), and the smaller wound utilised, might reduce the rate of contamination was studied.METHODSThe peroperative AC aspirates of 210 consecutive patients undergoing cataract surgery were assessed. In group 1, 100 patients underwent a

Bijan Beigi; William Westlake; Else Mangelschots; Bernard Chang; Walter Rich; Terry Riordan

1997-01-01

356

Hot water surface pasteurisation of lamb carcasses: microbial effects and cost-benefit considerations.  

PubMed

Although hot water pasteurisation of carcasses is accepted as a general intervention in USA, this is not the case in Europe. The aims of this study were (i) to evaluate the microbiological effects of hot water pasteurisation of lamb carcasses, both after slaughtering and dressing and following subsequent chilling and storage; (ii) to discuss hot water pasteurisation from a public health and cost-benefit perspective; (iii) to discuss the benefits of hot water pasteurisation compared with use of separate meat processing streams for high-risk carcasses; (iv) to evaluate the use of recycled hot water in a hygienic context and in relation to EU regulations; and (v) to consider the technological and sensory aspects of hot water pasteurisation of lamb carcasses. Samples were collected from 420 naturally contaminated lamb carcasses, with 50% of the carcasses (n=210) subject to hot water pasteurisation at 82 °C for 8s immediately after slaughter. Surface swab samples from 4500 cm² areas on carcasses were collected at slaughter, after chilling for 24 h, and after chilling for five days. The microbial analyses included Escherichia coli, Enterobacteriaceae, Bacillus cereus, Clostridium perfringens and aerobic plate count (APC). A resuscitation step using Tryptone Soya Agar was included in the microbiological analyses. Hot water pasteurisation significantly reduced the levels of E. coli, Enterobacteriaceae, B. cereus and APC (all P<0.001). E. coli colony forming unit (CFU) reduction was 99.5%, corresponding to a reduction of 1.85 log CFU per carcass. E. coli was isolated from 66% of control carcasses and from 26% of pasteurised carcasses. After 24h storage, the reduction in E. coli was increased to 2.02 log, and after five days E. coli could not be isolated from the pasteurised carcasses. These results suggest that surface pasteurisation could be an important and efficient procedure (critical control point) for reducing generic E. coli and thereby shiga toxin-producing E. coli on carcasses, and thus the risk for disease among consumers. The recycled water had acceptable physical and chemical parameters and no spore-forming bacteria were detected. Although some carcass discolouration was observed, after 24h the colour was acceptable. Our data provide relevant input for some of the data gaps regarding hot water pasteurisation and indicate that replacing the expensive system of separate processing of high-risk carcasses with hot water surface pasteurisation should be considered as a serious option. PMID:21356564

Hauge, Sigrun J; Wahlgren, Magnus; Røtterud, Ole-Johan; Nesbakken, Truls

2011-02-26

357

Versatile microbial surface-display for environmental remediation and biofuels production  

Microsoft Academic Search

Surface display is a powerful technique that uses natural microbial functional components to express proteins or peptides on the cell exterior. Since the reporting of the first surface-display system in the mid-1980s, a variety of new systems have been reported for yeast, Gram- positive and Gram-negative bacteria. Non-conventional display methods are emerging, eliminating the gener- ation of genetically modified microorganisms.

Cindy H. Wu; Ashok Mulchandani; Wilfred Chen

2008-01-01

358

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

359

Selected chemical contaminants in surface sediments of Commencement Bay and the Tacoma waterways, Washington, USA (revised)  

SciTech Connect

Eight metals, 21 organic priority pollutants, and 11 other contaminants and contaminant-related sediment characteristics were measured in surface sediments (upper 2 cm) at 21 locations in Commencement Bay and the Tacoma Waterways, Washington. Summary statistics were calculated and statistical approaches were applied to subsets of the data to classify sediment contamination. High concentrations of some contaminants appeared to be related to proximity to sources of contaminants. Depositional vectors and chemical-adsorption processes may also influence the spatial distribution of sediment contamination in the study area.

Schults, D.W.; Ferraro, S.P.; Ditsworth, G.R.; Sercu, K.A.

1987-01-01

360

Effects of nutritional input and diesel contamination on soil enzyme activities and microbial communities in Antarctic soils.  

PubMed

Pollution of Antarctic soils may be attributable to increased nutritional input and diesel contamination via anthropogenic activities. To investigate the effect of these environmental changes on the Antarctic terrestrial ecosystem, soil enzyme activities and microbial communities in 3 types of Antarctic soils were evaluated. The activities of alkaline phosphomonoesterase and dehydrogenase were dramatically increased, whereas the activities of ?-glucosidase, urease, arylsulfatase, and fluorescein diacetate hydrolysis were negligible. Alkaline phosphomonoesterase and dehydrogenase activities in the 3 types of soils increased 3- to 10-fold in response to nutritional input, but did not increase in the presence of diesel contamination. Consistent with the enzymatic activity data, increased copy numbers of the phoA gene, encoding an alkaline phosphomonoesterase, and the 16S rRNA gene were verified using quantitative real-time polymerase chain reaction. Interestingly, dehydrogenase activity and 16S rRNA gene copy number increased slightly after 30 days, even under diesel contamination, probably because of adaptation of the bacterial population. Intact Antarctic soils showed a predominance of Actinobacteria phylum (mostly Pseudonorcarida species) and other phyla such as Proteobacteria, Chloroflexi, Planctomycetes, Firmicutes, and Verrucomicrobia were present in successively lower proportions. Nutrient addition might act as a selective pressure on the bacterial community, resulting in the prevalence of Actinobacteria phylum (mostly Arthrobacter species). Soils contaminated by diesel showed a predominance of Proteobacteria phylum (mostly Phyllobacterium species), and other phyla such as Actinobacteria, Bacteroidetes, Planctomycetes, and Gemmatimonadetes were present in successively lower proportions. Our data reveal that nutritional input has a dramatic impact on bacterial communities in Antarctic soils and that diesel contamination is likely toxic to enzymes in this population. PMID:23274977

Han, Jiwon; Jung, Jaejoon; Hyun, Seunghun; Park, Hyun; Park, Woojun

2012-12-30

361

Investigation of microbial populations in the extremely metal-contaminated Coeur d'Alene River sediments.  

PubMed

The deposition of mine tailings generated from 125 years of sulfidic ore mining resulted in the enrichment of Coeur d'Alene River (CdAR) sediments with significant amounts of toxic heavy metals. A review of literature suggests that microbial populations play a pivotal role in the biogeochemical cycling of elements in such mining-impacted sedimentary environments. To assess the indigenous microbial communities associated with metal-enriched sediments of the CdAR, high-density 16S microarray (PhyloChip) and clone libraries specific to bacteria (16S rRNA), ammonia oxidizers (amoA), and methanogens (mcrA) were analyzed. PhyloChip analysis provided a comprehensive assessment of bacterial populations and detected the largest number of phylotypes in Proteobacteria followed by Firmicutes and Actinobacteria. Furthermore, PhyloChip and clone libraries displayed considerable metabolic diversity in indigenous microbial populations by capturing several chemolithotrophic groups such as ammonia oxidizers, iron-reducers and -oxidizers, methanogens, and sulfate-reducers in the CdAR sediments. Twenty-two phylotypes detected on PhyloChip could not be classified even at phylum level thus suggesting the presence of novel microbial populations in the CdAR sediments. Clone libraries demonstrated very limited diversity of ammonia oxidizers and methanogens in the CdAR sediments as evidenced by the fact that only Nitrosospira- and Methanosarcina-related phylotypes were retrieved in amoA and mcrA clone libraries, respectively. PMID:21331609

Rastogi, Gurdeep; Barua, Sutapa; Sani, Rajesh K; Peyton, Brent M

2011-02-18

362

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

Microsoft Academic Search

Understanding adaptation of biological communities to environmental change is a central issue in ecology and evolution. Metagenomic analysis of a stressed groundwater microbial community reveals that prolonged exposure to high concentrations of heavy metals, nitric acid and organic solvents (?50 years) has resulted in a massive decrease in species and allelic diversity as well as a significant loss of metabolic

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

2010-01-01

363

High Hydrostatic Pressure as a Method to Reduce Microbial Contamination of Porcine Blood Plasma  

Microsoft Academic Search

The suitability of high hydrostatic pressure as an alternative method to produce porcine blood plasma with a sufficient microbial stability without affecting its functional properties was evaluated. The effects of high pressure on plasma microorganisms were highly dependent on processing temperature. Treatments of 15 min at 450 MPa carried out at 5 'C led to reductions of about 90% in

D. Pares; E. Saguer; M. Toldra; C. Carretero

2001-01-01

364

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

2013-07-03

365

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

366

Review of the Knowledge of Microbial Contamination of the Russian Manned Spacecraft  

Microsoft Academic Search

The 15-year experience of orbital station Mir service demonstrated that specifically modified space vehicle environments allows for the consideration of spaceship habitats as a certain ecological niche of microbial community development and functioning, which was formed from the organisms of different physiological and taxonomical groups. The base unit of the orbital station (OS) Mir was launched on February 20, 1986,

N. D. Novikova

2004-01-01

367

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...

368

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

369

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

370

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

Microsoft Academic Search

The rate and extent of PAH biodegradation in a set of aged, crude oil contaminated model soils were measured in 90-week slurry bioremediation experiments. Soil properties such as organic matter content, mineral type, particle diameter, surface area, and porosity did not significantly influence the PAH biodegradation kinetics among the ten different model soils. A comparison of aged and freshly spiked

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

2002-01-01

371

Effects of Microbial Trophic Interactions on the Fate and Mobility of Soil Contaminants.  

National Technical Information Service (NTIS)

This project will be initiated by the establishment of a culture collection isolated from contaminated drag strip soil (DSS) and clean Hudson River Sediment (HRS). Careful isolation, characterization, and long term maintenance of these bacteria and protis...

R. A. Snyder

1998-01-01

372

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

373

Characterization of Metal-Reducing Microbial Communities from Acidic Subsurface Sediments Contaminated with Uranium(VI)  

Microsoft Academic Search

Extraction and processing of uranium ore during the Cold-War era have left many sites around the world contaminated with uranium. Leaching of uranium into the groundwater is of major concern because oxidized uranium, U(VI), is toxic, soluble, and therefore mobile in subsurface environments where the majority of contamination resides. Uranium [U(VI)] can be immobilized from water by its reduction from

Ellen McLain Edwards

2004-01-01

374

Molecular Characterization Of A Microbial Community From Uranium-Contaminated Acidic Sediment  

Microsoft Academic Search

The Field Research Center (FRC) in Oak Ridge, TN, was established by the U.S. Department of Energy’s Natural and Accelerated Bioremediation Research (NABIR) Program to develop strategies for bioremediation of contaminant metals and radionuclides. The FRC is centered on groundwater plumes that originate from former S-3 Waste Disposal Ponds located at the Y-12 Plant where acidic nitrate- and uranium-contaminated waste

Nadia North

2003-01-01

375

Bioremediation of contaminated surface water by immobilized Micrococcus roseus.  

PubMed

The problems caused by contaminated surface water have gradually become more serious in recent years. Although various remediation technologies were investigated, unfortunately, no efficient method was developed. In this paper, a new bioremediation technology was studied using Micrococcus roseus, which was immobilized in porous spherical beads by an improved polyvinyl alcohol (PVA) - sodium alginate (SA) embedding method. The experimental results indicated that COD removal rate could reach 64.7 % within 72 hours when immobilized M. roseus beads were used, which was ten times as high as that of free cells. The optimum inoculation rate of immobilized M. roseus beads was 10 % (mass percent of the beads in water sample, g g(-1)). Suitable aeration was proved necessary to enhance the bioremediation process. The immobilized cells had an excellent tolerance to pH and temperature changes, and were also more resistant to heavy metal stress compared with free cells. The immobilized M. roseus beads had an excellent regeneration capacity and could be reused after 180-day continuous usage. The Scanning Electronic Microscope (SEM) analysis showed that the bead microstructure was suitable for M. roseus growth, however, some defect structures should still be improved. PMID:16128392

Li, H; Li, P; Hua, T; Zhang, Y; Xiong, X; Gong, Z

2005-08-01

376

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

377

EFFECTS OF POLLUTANTS ON MICROBIAL ACTIVITIES IN ESTUARINE SURFACE FILMS  

EPA Science Inventory

Samples of inshore surface films from Escambia Bay, Florida and from sites in the North Sea yielded populations of aerobic, heterotrophic microorganisms up to 10 to the 8th power per ml or 1,000,000 per sq. cm. Hydrocarbonoclastic organisms were in relatively low populations. A c...

378

Recovery of Bacillus Spore Contaminants from Rough Surfaces: a Challenge to Space Mission Cleanliness Control?  

PubMed Central

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.

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

2011-01-01

379

Limitations of x-ray reflectometry in the presence of surface contamination  

NASA Astrophysics Data System (ADS)

Intentionally deposited thin films exposed to atmosphere often develop unintentionally deposited few-monolayer films of surface contamination. This contamination arises from the diverse population of volatile organics and inorganics in the atmosphere. Such surface contamination can affect the uncertainties in determination of thickness, roughness and density of thin-film structures by x-ray reflectometry (XRR). Here we study the effect of a 0.5 nm carbon surface contamination layer on thickness determination for a 20 nm titanium nitride thin film on silicon. Uncertainties calculated using Markov-chain Monte Carlo Bayesian statistical methods from simulated data of clean and contaminated TiN thin films are compared at varying degrees of data quality to study (1) whether synchrotron sources cope better with contamination than laboratory sources and (2) whether cleaning off the surface of thin films prior to XRR measurement is necessary. We show that, surprisingly, contributions to uncertainty from surface contamination can dominate uncertainty estimates, leading to minimal advantages in using synchrotron-over laboratory-intensity data. Further, even prior knowledge of the exact nature of the surface contamination does not significantly reduce the contamination's contribution to the uncertainty in the TiN layer thickness. We conclude, then, that effective and standardized cleaning protocols are necessary to achieve high levels of accuracy in XRR measurement.

Gil, D. L.; Windover, D.

2012-06-01

380

Antineoplastic drug contamination of surfaces throughout the hospital medication system in Canadian hospitals.  

PubMed

We previously reported that there is a potential for antineoplastic drug contamination throughout the hospital medication system (process flow of drug within a facility from delivery to waste disposal) due to the various surfaces contacted by health care workers. This article describes the contamination of these frequently contacted surfaces as well as identifies factors that may be associated with surface contamination. Surfaces which health care workers frequently contact were wiped and the concentration of cyclophosphamide (CP) was determined using high-performance liquid chromatography-tandem mass spectrometry. Descriptive and inferential statistical analyses were performed. A backward stepwise multiple linear regression was conducted to identify determinants associated with surface contamination. Overall, 229 surfaces were sampled, most on two occasions, for a total of 438 surface wipes. The mean CP concentration was 0.201 ng/cm(2), the geometric mean 0.019 ng/cm(2), and the geometric standard deviation 2.54, with a range of less than detection (LOD) to 26.1 ng/cm(2). (Method LOD was 0.356 ng/wipe; factoring in the surface area of the wiped surface, results in a sample LOD ranging from 0.00 to 0.049 ng/cm(2)). Our study found that frequently contacted surfaces at every stage of the hospital medication system had measureable levels of antineoplastic drug contamination. Two factors were statistically significant with respect to their association with surface contamination: (1) the stage of the hospital medication system, and (2) the number of job categories responsible for drug transport. The drug preparation stage had the highest average contamination. Those hospitals that had two or more drug transport job categories had higher levels of surface contamination. Neither the reported handling of CP prior to wipe sampling nor the cleaning of surfaces appeared to be associated with contamination. PMID:23668810

Hon, Chun-Yip; Teschke, Kay; Chu, Winnie; Demers, Paul; Venners, Scott

2013-01-01

381

Biogeochemical Processes and Microbial Characteristics Across Groundwater-Surface Water Boundaries  

Microsoft Academic Search

The flux of contaminants from ground water to surface water is spatially and temporally dynamic and a function of the variability of the hydrogeology, geochemistry, and biology within the boundary between groundwater and surface waters (i.e., the hyporheic zone). Currently, there lacks a basic understanding of processes within this interaction zone, and consequently, it is not possible to accurately predict

E. V. Arntzen; J. P. McKinley

2002-01-01

382

Soil heavy metal concentrations, microbial biomass and enzyme activities in a contaminated grassland ecosystem  

Microsoft Academic Search

Soil enzyme activities and microbial biomass were measured in a grassland ecosystem with a wide range of heavy metal concentrations ranging from 7.2 to 48.1 mmol kg?1 (As, Cd, Cr, Cu, Ni, Pb and Zn) in portions of the U.S. Army's Aberdeen Proving Ground, Maryland, U.S.A. Total and fluorescein diacetate active (FDA) fungal biomass, FDA-active bacterial biomass, substrate-induced respiration (SIR),

Roman G. Kuperman; Margaret M. Carreiro

1997-01-01

383

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

384

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

385

Microbial contamination of drinking water and disease outcomes in developing regions  

Microsoft Academic Search

Drinking water is a major source of microbial pathogens in developing regions, although poor sanitation and food sources are integral to enteric pathogen exposure. Gastrointestinal disease outcomes are also more severe, due to under-nutrition and lack of intervention strategies in these regions. Poor water quality, sanitation and hygiene account for some 1.7 million deaths a year world-wide (3.1% of all

Nicholas John Ashbolt

2004-01-01

386

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

SciTech Connect

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

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

2011-02-14

387

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

SciTech Connect

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

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

2011-12-31

388

[Microbial contamination of water by pipe and tube materials. 3. Behavior of E. coli, Citrobacter freundii and Klebsiella pneumoniae].  

PubMed

Materials water comes into contact with can promote the microbial growth as it could be shown before. The reaction of an unspecific microorganism flora and of Legionella pneumophila in pipes and hoses has been described in the two previous communications. The investigation with L. pneumophila has shown that even a pathogen organism can grow upon the materials. Therefore it was of special interest to prove whether indicator organisms for the testing of drinking water can grow in pipes and hoses as well. Escherichia coli, Citrobacter freundii and Klebsiella pneumoniae grew after the experimental contamination for many weeks on the rubber hose until the test was finally stopped, in the other pipes and hoses (glass, high-grade steel, PVC, PE, PA, PTFE and silicone) E. coli could be found for maximal 7 weeks, Citrobacter freundii for 1 week and Klebsiella pneumoniae for maximal 3 weeks. In the copper pipe the organisms could be found only for a few days. PMID:2673263

Schoenen, D; Schlömer, G

1989-08-01

389

Advection of surface-derived organic carbon fuels microbial reduction in Bangladesh groundwater  

PubMed Central

Chronic exposure to arsenic (As) by drinking shallow groundwater causes widespread disease in Bangladesh and neighboring countries. The release of As naturally present in sediment to groundwater has been linked to the reductive dissolution of iron oxides coupled to the microbial respiration of organic carbon (OC). The source of OC driving this microbial reduction—carbon deposited with the sediments or exogenous carbon transported by groundwater—is still debated despite its importance in regulating aquifer redox status and groundwater As levels. Here, we used the radiocarbon (14C) signature of microbial DNA isolated from groundwater samples to determine the relative importance of surface and sediment-derived OC. Three DNA samples collected from the shallow, high-As aquifer and one sample from the underlying, low-As aquifer were consistently younger than the total sediment carbon, by as much as several thousand years. This difference and the dominance of heterotrophic microorganisms implies that younger, surface-derived OC is advected within the aquifer, albeit more slowly than groundwater, and represents a critical pool of OC for aquifer microbial communities. The vertical profile shows that downward transport of dissolved OC is occurring on anthropogenic timescales, but bomb 14C-labeled dissolved OC has not yet accumulated in DNA and is not fueling reduction. These results indicate that advected OC controls aquifer redox status and confirm that As release is a natural process that predates human perturbations to groundwater flow. Anthropogenic perturbations, however, could affect groundwater redox conditions and As levels in the future.

Mailloux, Brian J.; Trembath-Reichert, Elizabeth; Cheung, Jennifer; Watson, Marlena; Stute, Martin; Freyer, Greg A.; Ferguson, Andrew S.; Ahmed, Kazi Matin; Alam, Md. Jahangir; Buchholz, Bruce A.; Thomas, James; Layton, Alice C.; Zheng, Yan; Bostick, Benjamin C.; van Geen, Alexander

2013-01-01

390

Structure of Sediment-Associated Microbial Communities along a Heavy-Metal Contamination Gradient in the Marine Environment  

PubMed Central

Microbial community composition and structure were characterized in marine sediments contaminated for >80 years with cadmium, copper, lead, and zinc. Four sampling sites that encompass a wide range of sediment metal loads were compared in a Norwegian fjord (Sørfjord). HCl-extractable metals and organic matter constantly decreased from the most contaminated site (S1) to the control site (S4). All sampling sites presented low polychlorinated biphenyl (PCB) concentrations (?7PCB < 7.0 ng g [dry weight]?1). The biomass ranged from 4.3 × 108 to 13.4 × 108 cells g (dry weight) of sediments?1 and was not correlated to metal levels. Denaturing gradient gel electrophoresis indicated that diversity was not affected by the contamination. The majority of the partial 16S rRNA sequences obtained were classified in the ?- and ?-Proteobacteria and in the Cytophaga-Flexibacter-Bacteroides (CFB) bacteria. Some sequences were closely related to other sequences from polluted marine sediments. The abundances of seven phylogenetic groups were determined by using fluorescent in situ hybridization (FISH). FISH was impaired in S1 by high levels of autofluorescing particles. For S2 to S4, the results indicated that the HCl-extractable Cu, Pb, and Zn were negatively correlated with the abundance of ?-Proteobacteria and CFB bacteria. ?-Proteobacteria were not correlated with HCl-extractable metals. Bacteria of the Desulfosarcina-Desulfococcus group were detected in every site and represented 6 to 14% of the DAPI (4?,6?-diamidino-2-phenylindole) counts. Although factors other than metals may explain the distribution observed, the information presented here may be useful in predicting long-term effects of heavy-metal contamination in the marine environment.

Gillan, David C.; Danis, Bruno; Pernet, Philippe; Joly, Guillemette; Dubois, Philippe

2005-01-01

391

Comparison of microbial contamination of enteral feeding solution between repeated use of administration sets after washing with water and after washing followed by disinfection  

Microsoft Academic Search

We compared microbial contamination of in-use enteral feeding solution from repeatedly used administration sets (a delivery bag and an infusion tube) after washing with water or washing followed by disinfection. In eight hospitals where administration sets were re-used after washing with water, residual solution was collected from both the delivery bag and the distal end of the infusion tube immediately

S. Oie; A. Kamiya

2001-01-01

392

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

393

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

394

An investigation of microbial adhesion to natural and synthetic polysaccharide-based films and its relationship with the surface energy components.  

PubMed

In recent years, polysaccharide-based films have been developed for many applications. Some of these are in the pharmaceutical industry, where the adhesion of microorganisms to surfaces is a concern. After adhesion of a microorganism to a solid surface has taken place, the subsequent biofilm formed can act as a vehicle for spreading infections. The aim of this study is to compare the bacterial adhesion of E. coli and S. aureus from a contaminated solid model (Tryptone Soya Agar) to a range of polysaccharide-based films. These polysaccharide-based films consist of different natural starches (potato, cassava, wheat, pea and rice) and synthetic polymers hydroxyl-propyl cellulose (HPC) and carboxyl methyl cellulose (CMC)). The surface energy parameters of the films were calculated from the contact angle measurements by the sessile drop method. Apolar and polar liquids (water, formamide and hexadecane) and the Lifshitz-Van der Waals/acid-base (LW/AB) approach were used according to the method of Van Oss, Chaundhury and Good. The surface properties of the films were also correlated to the microbial adhesion. This indicated that, for both E. coli and S. aureus, the surface roughness did not affect the microbial adhesion. Only gamma(sAB) had any correlation with the microbial adhesion and gamma(sLW) was almost constant for all the various polysaccharide films tested. In addition, the electron-donor properties of the materials, exhibited via gamma(s+), were positively correlated with the adhesion of S. aureus but not with E. coli. This was in agreement with the results of the MATS (Microbial Adhesion To Solvents) test performed on the two bacteria. This revealed that only S. aureus presented an electron-acceptor characteristic. PMID:18712504

Prokopovich, Polina; Perni, Stefano

2008-08-20

395

Impact of wash water quality on sensory and microbial quality, including Escherichia coli cross-contamination, of fresh-cut escarole.  

PubMed

The influence of wash water quality on the microbial load and sensory quality of fresh-cut escarole was evaluated. Additionally, the degree of Escherichia coli cross-contamination between inoculated and uninoculated products after washing was also studied. Three types of wash water, i.e., potable water, diluted recirculated water, and recirculated water, containing different microbial counts and organic loads, were used. Results showed that microbial load (P > or = 0.02) and sensory quality (P > 0.625) of the product were not influenced by the water quality after washing and storage. Cross-contamination between inoculated and uninoculated products was observed after washing, as there was significant transmission of E. coli cells from the product to the wash water (P < 0.001). When fresh-cut escarole was contaminated at a high inoculum level (5.1 log CFU/g), wash water quality influenced the level of cross-contamination, as the highest E. coli load (P < 0.001) was shown in uninoculated fresh-cut escarole washed with recirculated water. However, when fresh-cut escarole was contaminated at a low inoculum level (3.2 log CFU/g), the wash water quality did not influence the level of cross-contamination, as E. coli slightly increased, although not at a statistically significant level, after the uninoculated product was washed with recirculated water (P > 0.035). Therefore, the contamination level may impact the effectiveness of water quality to reduce pathogen concentrations. It was clearly observed that cross-contamination of fresh-cut escarole with E. coli occurs, thereby suggesting that small amounts of contamination could impact the overall product and indicating the necessity of using wash water sanitizers to eliminate pathogens. PMID:19244906

Allende, Ana; Selma, Maria V; López-Gálvez, Francisco; Villaescusa, Raquel; Gil, María I

2008-12-01

396

Microbial biomass and nitrogen transformations in surface soils strongly acidified by volcanic hydrogen sulfide deposition in Osorezan, Japan  

Microsoft Academic Search

Volcanic acidification has created unique ecosystems that have had to adapt to the acidic environments in volcanic regions. To characterize the primary microbial properties of strongly acidified soils in such environments, we investigated microbial biomass, nitrogen transformations and other relevant chemical properties in the surface soils of solfatara and forests from Osorezan, a typical volcanic region in Japan, and compared

Mirai Watanabe; Shigeki Yamamura; Takejiro Takamatsu; Masami K. Koshikawa; Seiji Hayashi; Tomoyoshi Murata; Shoko S. Saito; Kazuyuki Inubushi; Kazunori Sakamoto

2010-01-01

397

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.

Sobolev, Dmitri; Begonia, Maria F. T.

2008-01-01

398

Impedance measurements to assess microbial contamination of ready-to-use vegetables  

Microsoft Academic Search

An impedometric method for estimating the microbial load of ready-to-use vegetables, either inoculated or not inoculated\\u000a with antimicrobial-producing lactic acid bacteria, was investigated. The correlation (R\\u000a \\u000a 2) between total mesophilic bacteria (log cfu\\/g) and time to detection was 0.889. A discrepancy was observed for the impedometric\\u000a measurement of low coliforms counts, particularly in samples inoculated with lactic acid bacteria and

Carla Orsi; Sandra Torriani; Bruno Battistotti; M. Vescovo

1997-01-01

399

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

400

Molecular contamination effects on the thermal emittance of highly reflective surfaces at cryogenic temperatures  

Microsoft Academic Search

For contamination effects on thermal control surfaces, changes in solar absorptance are the effect noted. Emittance of the surface is not normally affected. The SIRTF (Space InfraRed Telescope Facility) and NGST (Next Generation Space Telescope) spacecraft will fly large low emissivity surfaces (e.g. aluminized Kapton shields and gold mirrors). During the orbital missions, these surfaces will not be exposed to

Chien W. Chang

2002-01-01

401

Microbial biomass, activity, and organic matter accumulation in soils contaminated with heavy metals  

Microsoft Academic Search

Chemical characteristics and some parameters related to biological components were determined in 16 soils from a fairly homogeneous area in the north of Italy, contaminated with different levels of heavy metals. Correlation analysis of the parameters studied showed close positive relationships among the metals and with the organic C content in the soils studied. Negative relationships were observed among the

Giovanni Valsecchi; Carmen Gigliotti; Anna Farini

1995-01-01