contamination resistant capability: Topics by Science.gov

Sample records for contamination resistant capability

Characterization of a fluoride-resistant bacterium Acinetobacter sp. RH5 towards assessment of its water defluoridation capability

NASA Astrophysics Data System (ADS)

Mukherjee, Shraboni; Yadav, Vaibhav; Mondal, Madhumanti; Banerjee, Soumya; Halder, Gopinath

2017-07-01

The present study investigates the defluoridation capability of fluoride-resistant bacteria from contaminated groundwater collected from Asanjola and Madhabpur, West Bengal, India. Seven strains of fluoride-resistant bacteria were isolated employing culture media containing 10-250 mg/L of fluoride to evaluate their ability in reducing fluoride concentration in water. Five isolates exhibited significant amount of reduction in fluoride. Isolate RH5 achieved a maximum fluoride removal of 25.7 % from the media at 30 °C and pH 7 after 8 days of incubation. Based on morphological, physiological characteristics and analysis of 16S rDNA gene sequence, isolate RH5 was identified as Acinetobacter sp. RH5. Growth of RH5 was analysed at a diverse pH range, and it could thrive at pH 5-10. The present investigation revealed that the selective pressure of fluoride results in growth of fluoride-resistant bacteria capable of secreting high-affinity anion-binding compounds. This bacterium played a dominant bioremediative role by concentrating the anions so that they become less available. Hence, the fluoride-resistant bacteria, Acinetobacter sp. RH5, could be used as a promising strain for application in water defluoridation from contaminated sites.
Near surface geophysical techniques on subsoil contamination: laboratory experiments

NASA Astrophysics Data System (ADS)

Capozzoli, Luigi; Giampaolo, Valeria; Rizzo, Enzo

2016-04-01

Hydrocarbons contamination of soil and groundwater has become a serious environmental problem, because of the increasing number of accidental spills caused by human activities. The starting point of any studies is the reconstruction of the conceptual site model. To make valid predictions about the flow pathways following by hydrocarbons compound is necessary to make a correct reconstruction of their characteristics and the environment in which they move. Near-surface geophysical methods, based on the study of electrical and electromagnetic properties, are proved to be very useful in mapping spatial distribution of the organic contaminants in the subsurface. It is well known, in fact, that electrical properties of the porous media are significantly influenced by hydrocarbons because, when contaminants enter the rock matrix, surface reaction occur between the contaminant and the soil grain surface. The main aim of this work is to investigate the capability of near-surface geophysical methods in mapping and monitoring spatial distribution of contaminants in a controlled setting. A laboratory experiment has been performed at the Hydrogeosite Laboratory of CNR-IMAA (Marsico Nuovo, PZ) where a box-sand has been contaminated by diesel. The used contaminant is a LNAPL, added to the sand through a drilled pipe. Contaminant behaviour and its migration paths have been monitored for one year by Electrical Resistivity measurements. In details, a Cross Borehole Electrical Resistivity Tomography techniques were used to characterize the contamination dynamics after a controlled hydrocarbon spillage occurring in the vadose zone. The approach with cross-borehole resistivity imaging provide a great advantage compared to more conventional surface electrical resistivity tomography, due to the high resolution at high depth (obviously depending on the depth of the well instrumented for the acquisition). This method has been shown to provide good information on the distribution of electrical properties of the subsoil at high depths and, in some cases, a detailed assessment of dynamic processes in the subsurface environment (Binley et al., 2002). Our study confirms the link between hydrocarbons contamination and geoelectrical signal and the capability of cross-hole electrical resistivity tomographies to realize a non-invasive characterization of LNAPL contamination of the media. Although, the electrical behaviour is much more complex and the relation with the contaminants depends also by time of investigation.
Interactions between earthworms and arsenic in the soil environment: a review.

PubMed

Langdon, Caroline J; Piearce, Trevor G; Meharg, Andrew A; Semple, Kirk T

2003-01-01

Chemical pollution of the environment has become a major source of concern. In particular, many studies have investigated the impact of pollution on biota in the environment. Studies on metalliferous contaminated mine spoil wastes have shown that some soil organisms have the capability to become resistant to metal/metalloid toxicity. Earthworms are known to inhabit arsenic-rich metalliferous soils and, due to their intimate contact with the soil, in both the solid and aqueous phases, are likely to accumulate contaminants present in mine spoil. Earthworms that inhabit metalliferous contaminated soils must have developed mechanisms of resistance to the toxins found in these soils. The mechanisms of resistance are not fully understood; they may involve physiological adaptation (acclimation) or be genetic. This review discusses the relationships between earthworms and arsenic-rich mine spoil wastes, looking critically at resistance and possible mechanisms of resistance, in relation to soil edaphic factors and possible trophic transfer routes.
Klebsiella sp. FIRD 2, a TBT-resistant bacterium isolated from contaminated surface sediment along Strait of Johor Malaysia.

PubMed

Abubakar, Abdussamad; Mustafa, Muskhazli B; Johari, Wan Lutfi Wan; Zulkifli, Syaizwan Zahmir; Ismail, Ahmad; Mohamat-Yusuff, Ferdaus Binti

2015-12-15

A possible tributyltin (TBT)-degrading bacterium isolated from contaminated surface sediment was successfully identified as Klebsiella sp. FIRD 2. It was found to be the best isolate capable of resisting TBT at a concentration of 1000 μg L(-1). This was a concentration above the reported contaminated level at the sampling station, 790 μg L(-1). Further studies revealed that the isolate was Gram negative and resisted TBT concentrations of up to 1500 μg L(-1) in a Minimal Salt Broth without the addition of any carbon source within the first 48 h of incubation. It is expected that additional work could be conducted to check the degradation activity of this new isolate and possibly improve the degradation capacity in order to contribute to finding a safe and sustainable remediation solution of TBT contamination. Copyright © 2015 Elsevier Ltd. All rights reserved.
Metal resistance mechanisms in Gram-negative bacteria and their potential to remove Hg in the presence of other metals.

PubMed

Giovanella, Patricia; Cabral, Lucélia; Costa, Alexandre Pereira; de Oliveira Camargo, Flávio Anastácio; Gianello, Clesio; Bento, Fátima Menezes

2017-06-01

Contamination of the environment by heavy metals has been increasing in recent years due to industrial activities. Thus research involving microorganisms capable of surviving in multi-contaminated environments is extremely important. The objectives of the present study were to evaluate the removal of mercury alone and in the presence of cadmium, nickel and lead by four mercury-resistant microorganisms; estimate the removal of Cd, Ni and Pb; understand the mechanisms involved (reduction, siderophores, biofilms, biosorption and bioaccumulation) in the metal resistance of the isolate Pseudomonas sp. B50D; and determine the capacity of Pseudomonas sp. B50D in removing Hg, Cd, Ni and Pb from an industrial effluent. It was shown that the four isolates evaluated were capable of removing from 62% to 95% of mercury from a culture medium with no addition of other metals. The isolate Pseudomonas sp. B50D showed the best performance in the removal of mercury when evaluated concomitantly with other metals. This isolate was capable of removing 75% of Hg in the presence of Cd and 91% in the presence of Ni and Pb. With respect to the other metals it removed 60%, 15% and 85% of Cd, Ni and Pb, respectively. In tests with effluent, the isolate Pseudomonas sp. B50D removed 85% of Hg but did not remove the other metals. This isolate presented reduction, biosorption, biofilm production and siderophore production as its metal resistance mechanisms. Pseudomonas sp. B50D was thus a candidate with potential for application in the bioremediation of effluents with complex metal contaminations. Copyright © 2017 Elsevier Inc. All rights reserved.
Using Contaminant Transport Simulations to Optimize Electrical Resistivity Tomography Survey Design for Improved Contaminant Detection at Lined Ponds

NASA Astrophysics Data System (ADS)

Herring, T.; Pidlisecky, A.

2015-12-01

The saline flowback water produced during hydraulic fracturing is often stored in lined surface ponds. Leakage from these ponds poses a significant environmental threat and there is a need for a reliable and economical long term monitoring strategy. Electrical resistivity tomography (ERT), being sensitive to changes in groundwater salinity, is therefore well suited to such a problem. The goal of this work is to compare the leak detection capabilities of a surface ERT array and a downhole ERT array. In this study several plausible 3D electrical conductivity models were created that simulated a contaminant plume evolving over time, using realistic contaminant concentrations, plume geometries, water saturation profiles, and seasonal temperature profiles. The forward modeled data were used to identify the advantages and drawbacks of using each ERT array orientation.
Long-term autonomous resistivity monitoring of oil-contaminated sediments from the Deepwater Horizon spill

NASA Astrophysics Data System (ADS)

Heenan, J. W.; Slater, L. D.; Ntarlagiannis, D.; Atekwana, E. A.; Ross, C.; Nolan, J. T.; Atekwana, E. A.; Werkema, D. D.; Fathepure, B.

2012-12-01

We conducted a long-term electrical resistivity survey at Grand Terre 1 (GT1) Island off the coast of Louisiana, a site contaminated with crude oil associated with the April 2010 BP Deepwater Horizon oil spill. Electrical resistivity has proven sensitivity to biogeochemical processes associated with the biodegradation of hydrocarbons in the subsurface. However, most of these studies have been in freshwater environments and for aged spills. The BP Deepwater Horizon oil spill therefore provided an unprecedented opportunity to capture the early time biogeophysical signals resulting from the physical, chemical and microbial transformation of crude oil in highly saline environments. We used a multi-channel resistivity system powered by solar panels to obtain continuous measurements twice a day on both a surface array and two shallow borehole arrays. This system operated for approximately 1.5 years and provided a unique long-term dataset of resistivity changes. Temperature and specific conductance values for the shallow groundwater were continuously logged. . Resistivity changes likely associated with biodegradation processes were then isolated from these environmental factors by modeling. In addition, groundwater was sampled for geochemical analyses from wells installed at the study site and soil samples were collected for microbial analyses at several locations, including both contaminated and uncontaminated locations. Microcosms were set up to determine the biodegradation potential of indigenous populations, and microbial diversity analysis was used to determine microbial community composition. Surface and borehole resistivity arrays revealed an initial resistive anomaly co-located with the known contamination. Pixel time series analysis of an inverted time sequence of resistivity sections highlighted differing responses between contaminated and uncontaminated locations. The contaminated locations exhibit persistent resistivity decreases over time, whereas areas outside of the contaminated location exhibit relatively uniform resistivity or show clear evidence of seasonal effect. Temperature-corrected resistivity changes show no direct correlation with pore fluid specific conductance changes, suggesting that specific conductance changes (e.g. due to tides) have little influence on imaged resistivity structure. Microbial data suggest that resistivity changes within the contaminated location resulted from biodegradation, showing the presence of native populations capable of degrading aromatic hydrocarbons at salinities ranging from 6 to 15 % NaCl within the contaminated location. Aqueous geochemical measurements performed on samples from the site further indicate that at depth intervals coincident with the resistivity anomaly, marked increases in the concentration of dissolved inorganic carbon (DIC) were observed suggesting biodegradation of petroleum hydrocarbon although other DIC generating processes such as organic matter degradation coupled to sulfate and iron reduction were also prominent. This experiment demonstrates the potential viability of long-term autonomous electrical monitoring as a means of decreasing the frequency of more costly and invasive chemical analysis of natural attenuation.
Fiber length and orientation prevent migration in fluid filters

NASA Technical Reports Server (NTRS)

Reiman, P. A.

1966-01-01

Stainless steel fiber web filter resists fiber migration which causes contamination of filtered fluids. This filter is capable of holding five times more particulate matter before arbitrary cutoff pressure drop and shows excellent retention in fuel flow at high rates.
Phytoremediation: plant-endophyte partnerships take the challenge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weyens, N.; van der Lelie, D.; Taghavi, S.

A promising field to exploit plant-endophyte partnerships is the remediation of contaminated soils and (ground) water. Many plant growth promoting endophytes can assist their host plant to overcome contaminant-induced stress responses, thus providing improved plant growth. During phytoremediation of organic contaminants, plants can further benefit from endophytes possessing appropriate degradation pathways and metabolic capabilities, leading to more efficient contaminant degradation and reduction of both phytotoxicity and evapotranspiration of volatile contaminants. For phytoremediation of toxic metals, endophytes possessing a metal-resistance/sequestration system can lower metal phytotoxicity and affect metal translocation to the above-ground plant parts. Furthermore, endophytes that can degrade organic contaminantsmore » and deal with or, even better, improve extraction of the metals offer promising ways to improve phytoremediation of mixed pollution.« less
Mobilome differences between Salmonella enterica serovars Anatum and Typhimurium isolated from cattle and humans and potential impact on virulence

USDA-ARS?s Scientific Manuscript database

Salmonella enterica subsp. enterica is an important group of pathogens capable of inhabiting a range of niches and hosts with varying degrees of impact, from commensal colonization to invasive infection. Recent outbreaks of multi-drug resistant S. enterica, attributed to consumption of contaminated ...
GEOPHYSICS AND SITE CHARACTERIZATION AT THE HANFORD SITE THE SUCCESSFUL USE OF ELECTRICAL RESISTIVITY TO POSITION BOREHOLES TO DEFINE DEEP VADOSE ZONE CONTAMINATION - 11509

DOE Office of Scientific and Technical Information (OSTI.GOV)

GANDER MJ; LEARY KD; LEVITT MT

2011-01-14

Historic boreholes confirmed the presence of nitrate and radionuclide contaminants at various intervals throughout a more than 60 m (200 ft) thick vadose zone, and a 2010 electrical resistivity survey mapped the known contamination and indicated areas of similar contaminants, both laterally and at depth; therefore, electrical resistivity mapping can be used to more accurately locate characterization boreholes. At the Hanford Nuclear Reservation in eastern Washington, production of uranium and plutonium resulted in the planned release of large quantities of contaminated wastewater to unlined excavations (cribs). From 1952 until 1960, the 216-U-8 Crib received approximately 379,000,000 L (100,000,000 gal) ofmore » wastewater containing 25,500 kg (56,218 lb) uranium; 1,029,000 kg (1,013 tons) of nitrate; 2.7 Ci of technetium-99; and other fission products including strontium-90 and cesium-137. The 216-U-8 Crib reportedly holds the largest inventory of waste uranium of any crib on the Hanford Site. Electrical resistivity is a geophysical technique capable of identifying contrasting physical properties; specifically, electrically conductive material, relative to resistive native soil, can be mapped in the subsurface. At the 216-U-8 Crib, high nitrate concentrations (from the release of nitric acid [HNO{sub 3}] and associated uranium and other fission products) were detected in 1994 and 2004 boreholes at various depths, such as at the base of the Crib at 9 m (30 ft) below ground surface (bgs) and sporadically to depths in excess of 60 m (200 ft) bgs. These contaminant concentrations were directly correlative with the presence of observed low electrical resistivity responses delineated during the summer 2010 geophysical survey. Based on this correlation and the recently completed mapping of the electrically conductive material, additional boreholes are planned for early 2011 to identify nitrate and radionuclide contamination: (a) throughout the entire vertical length of the vadose zone (i.e., 79 m [260 ft] bgs) within the footprint of the Crib, and (b) 15 to 30 m (50 to 100 ft) east of the Crib footprint, where contaminants are inferred to have migrated through relatively permeable soils. Confirmation of the presence of contamination in historic boreholes correlates well with mapping from the 2010 survey, and serves as a basis to site future characterization boreholes that will likely intersect contamination both laterally and at depth.« less
Estimating the capability of microalgae to physiological acclimatization and genetic adaptation to petroleum and diesel oil contamination.

PubMed

Romero-Lopez, Julia; Lopez-Rodas, Victoria; Costas, Eduardo

2012-11-15

There is increasing scientific interest in how phytoplankton reacts to petroleum contamination, since crude oil and its derivatives are generating extensive contamination of aquatic environments. However, toxic effects of short-term petroleum exposure are more widely known than the adaptation of phytoplankton to long-term petroleum exposure. An analysis of short-term and long-term effects of petroleum exposure was done using experimental populations of freshwater (Scenedesmus intermedius and Microcystis aeruginosa) and marine (Dunaliella tertiolecta) microalgae isolated from pristine sites without crude oil product contamination. These strains were exposed to increased levels of petroleum and diesel oil. Short-term exposure to petroleum or diesel oil revealed a rapid inhibition of photosynthetic performance and cell proliferation in freshwater and marine phytoplankton species. A broad degree of inter-specific variation in lethal contamination level was observed. When different strains were exposed to petroleum or diesel oil over the long-term, the cultures showed massive destruction of the sensitive cells. Nonetheless, after further incubation, some cultures were able to grow again due to cells that were resistant to the toxins. By means of a fluctuation analysis, discrimination between cells that had become resistant due to physiological acclimatization and resistant cells arising from rare spontaneous mutations was accomplished. In addition, an analysis was done as to the maximum capacity of adaptation to a gradual contamination process. An experimental ratchet protocol was used, which maintains a strong selection pressure in a temporal scale up to several months over very large experimental populations of microalgae. Microalgae are able to survive to petroleum contamination as a result of physiological acclimatization without genetic changes. However, when petroleum concentration exceeds the physiological limits, survival depends exclusively on the occurrence on mutations that confer resistance and subsequent selection of these mutants. Finally, it is certain that further mutations and selection will ultimately determine adaptation of microalgae to the environmental forcing. Copyright © 2012 Elsevier B.V. All rights reserved.
A dual layer hair array of the brown lacewing: repelling water at different length scales.

PubMed

Watson, Jolanta A; Cribb, Bronwen W; Hu, Hsuan-Ming; Watson, Gregory S

2011-02-16

Additional weight due to contamination (water and/or contaminating particles) can potentially have a detrimental effect on the flight capabilities of large winged insects such as butterflies and dragonflies. Insects where the wing surface area-body mass ratio is very high will be even more susceptible to these effects. Water droplets tend to move spontaneously off the wing surface of these insects. In the case of the brown lacewing, the drops effectively encounter a dual bed of hair springs with a topographical structure which aids in the hairs resisting penetration into water bodies. In this article, we demonstrate experimentally how this protective defense system employed by the brown lacewing (Micromus tasmaniae) aids in resisting contamination from water and how the micro- and nanostructures found on these hairs are responsible for quickly shedding water from the wing which demonstrates an active liquid-repelling surface. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Multilayer Perceptron for Robust Nonlinear Interval Regression Analysis Using Genetic Algorithms

PubMed Central

2014-01-01

On the basis of fuzzy regression, computational models in intelligence such as neural networks have the capability to be applied to nonlinear interval regression analysis for dealing with uncertain and imprecise data. When training data are not contaminated by outliers, computational models perform well by including almost all given training data in the data interval. Nevertheless, since training data are often corrupted by outliers, robust learning algorithms employed to resist outliers for interval regression analysis have been an interesting area of research. Several approaches involving computational intelligence are effective for resisting outliers, but the required parameters for these approaches are related to whether the collected data contain outliers or not. Since it seems difficult to prespecify the degree of contamination beforehand, this paper uses multilayer perceptron to construct the robust nonlinear interval regression model using the genetic algorithm. Outliers beyond or beneath the data interval will impose slight effect on the determination of data interval. Simulation results demonstrate that the proposed method performs well for contaminated datasets. PMID:25110755
Multilayer perceptron for robust nonlinear interval regression analysis using genetic algorithms.

PubMed

Hu, Yi-Chung

2014-01-01

On the basis of fuzzy regression, computational models in intelligence such as neural networks have the capability to be applied to nonlinear interval regression analysis for dealing with uncertain and imprecise data. When training data are not contaminated by outliers, computational models perform well by including almost all given training data in the data interval. Nevertheless, since training data are often corrupted by outliers, robust learning algorithms employed to resist outliers for interval regression analysis have been an interesting area of research. Several approaches involving computational intelligence are effective for resisting outliers, but the required parameters for these approaches are related to whether the collected data contain outliers or not. Since it seems difficult to prespecify the degree of contamination beforehand, this paper uses multilayer perceptron to construct the robust nonlinear interval regression model using the genetic algorithm. Outliers beyond or beneath the data interval will impose slight effect on the determination of data interval. Simulation results demonstrate that the proposed method performs well for contaminated datasets.
Advances in deep-UV processing using cluster tools

NASA Astrophysics Data System (ADS)

Escher, Gary C.; Tepolt, Gary; Mohondro, Robert D.

1993-09-01

Deep-UV laser lithography has shown the capability of supporting the manufacture of multiple generations of integrated circuits (ICs) due to its wide process latitude and depth of focus (DOF) for 0.2 micrometers to 0.5 micrometers feature sizes. This capability has been attained through improvements in deep-UV wide field lens technology, excimer lasers, steppers and chemically amplified, positive deep-UV resists. Chemically amplified deep-UV resists are required for 248 nm lithography due to the poor absorption and sensitivity of conventional novolac resists. The acid catalyzation processes of the new resists requires control of the thermal history and environmental conditions of the lithographic process. Work is currently underway at several resist vendors to reduce the need for these controls, but practical manufacturing solutions exist today. One of these solutions is the integration of steppers and resist tracks into a `cluster tool' or `Lithocell' to insure a consistent thermal profile for the resist process and reduce the time the resist is exposed to atmospheric contamination. The work here reports processing and system integration results with a Machine Technology, Inc (MTI) post-exposure bake (PEB) track interfaced with an advanced GCA XLS 7800 deep-UV stepper [31 mm diameter, variable NA (0.35 - 0.53) and variable sigma (0.3 - 0.74)].
Regenerable adsorption system

NASA Technical Reports Server (NTRS)

Roychoudhury, Subir (Inventor); Perry, Jay (Inventor); Walsh, Dennis (Inventor)

2006-01-01

A method for regenerable adsorption includes providing a substrate that defines at least one layer of ultra short channel length mesh capable of conducting an electrical current therethrough, coating at least a portion of the substrate with a desired sorbent for trace contaminant control or CO.sub.2 sorption, resistively heating the substrate, and passing a flowstream through the substrate and in contact with the sorbent.
Quo vadis? – Monitoring Campylobacter in Germany

PubMed Central

Stingl, K.; Knüver, M.-T.; Vogt, P.; Buhler, C.; Krüger, N.-J.; Alt, K.; Tenhagen, B.-A.; Hartung, M.; Schroeter, A.; Ellerbroek, L.; Appel, B.; Käsbohrer, A.

2012-01-01

Campylobacter is a poorly recognized foodborne pathogen, leading the statistics of bacterially caused human diarrhoea in Europe during the last years. In this review, we present qualitative and quantitative German data obtained in the framework of specific monitoring programs and from routine surveillance. These also comprise recent data on antimicrobial resistances of food isolates. Due to the considerable reduction of in vitro growth capabilities of stressed bacteria, there is a clear discrepancy between the detection limit of Campylobacter by cultivation and its infection potential. Moreover, antimicrobial resistances of Campylobacter isolates established during fattening of livestock are alarming, since they constitute an additional threat to human health. The European Food Safety Authority (EFSA) discusses the establishment of a quantitative limit for Campylobacter contamination of broiler carcasses in order to achieve an appropriate level of protection for consumers. Currently, a considerable amount of German broiler carcasses would not comply with this future criterion. We recommend Campylobacter reduction strategies to be focussed on the prevention of fecal contamination during slaughter. Decontamination is only a sparse option, since the reduction efficiency is low and its success depends on the initial contamination concentration. PMID:24611125
Multi-metal resistance and plant growth promotion potential of a wastewater bacterium Pseudomonas aeruginosa and its synergistic benefits.

PubMed

Biswas, Jayanta Kumar; Mondal, Monojit; Rinklebe, Jörg; Sarkar, Santosh Kumar; Chaudhuri, Punarbasu; Rai, Mahendra; Shaheen, Sabry M; Song, Hocheol; Rizwan, Muhammad

2017-12-01

Water and soil pollution by toxic heavy metals (HMs) is increasing globally because of increase in population, industrialization and urbanization. It is a burning problem for the public, scientists, academicians and politicians how to tackle the toxic contaminants which jeopardize the environment. One possible solution for pollution abatement is a bioremediation-effective and innovative technology that uses biological systems for treatment of contaminants. Many bacteria synthesize indole-3-acetic acid (IAA) which is a product of L-tryptophan metabolism and belongs to the auxin class of plant growth-promoting hormone. The present study aimed at assessing the resistance pattern of wastewater bacteria against multiple HMs and plant growth promotion activity associated with IAA. A Gram-negative bacterial strain Pseudomonas aeruginosa KUJM was isolated from Kalyani Sewage Treatment Plant. This strain showed the potential to tolerate multiple contaminations such as As(III) (50 mM), As(V) (800 mM), Cd (8 mM), Co (18 mM), Cu (7 mM), Cr (2.5 mM), Ni (3 mM) and Zn (14 mM). The capability of IAA production at different tryptophan concentration (1, 2, 5 and 10 mg mL -1 ) was determined, and seed germination-enhancing potential was also estimated on lentil (Lens culinaris). Such type of HM-resistant, IAA-producing and seed germination-enhancing P. aeruginosa KUJM offer great promise as inoculants to promote plant growth in the presence of toxic HMs, as well as plant inoculant systems useful for phytoremediation of polluted soils. Hence, P. aeruginosa KUJM finds significant applications in HM-contaminated poor agricultural field as well as in bioremediation of HM-contaminated wastewater system.
Mortality from duck plague virus in immunosuppressed adult mallard ducks

USGS Publications Warehouse

Goldberg, Diana R.; Yuill, Thomas M.; Burgess, E.C.

1990-01-01

Environmental contaminants contain chemicals that, if ingested, could affect the immunological status of wild birds, and in particular, their resistance to infectious disease. Immunosuppression caused by environmental contaminants, could have a major impact on waterfowl populations, resulting in increased susceptibility to contagious disease agents. Duck plague virus has caused repeated outbreaks in waterfowl resulting in mortality. In this study, several doses of cyclophosphamide (CY), a known immunosuppressant, were administered to adult mallards (Anas platyrhynchos) to determine if a resultant decrease in resistance to a normally sub-lethal strain of duck plague virus would occur, and induce mortality in these birds. Death occurred in birds given CY only, and in birds given virus and CY, but not in those given virus only. There was significantly greater mortality and more rapid deaths in the duck plague virus-infected groups than in groups receiving only the immunosuppressant. A positively correlated dose-response effect was observed with CY mortalities, irrespective of virus exposure. A fuel oil and a crude oil, common environmental contaminants with immunosuppressive capabilities, were tested to determine if they could produce an effect similar to that of CY. Following 28 days of oral oil administration, the birds were challenged with a sub-lethal dose of duck plague virus. No alteration in resistance to the virus (as measured by mortality) was observed, except in the positive CY control group.

Mortality from duck plague virus in immunosuppressed adult mallard ducks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldberg, D.R.; Yuill, T.M.; Burgess, E.C.

Environmental contaminants contain chemicals that, if ingested, could affect the immunological status of wild birds, and in particular, their resistance to infectious disease. Immunosuppression caused by environmental contaminants, could have a major impact on waterfowl populations, resulting in increased susceptibility to contagious disease agents. Duck plague virus has caused repeated outbreaks in waterfowl resulting in mortality. In this study, several doses of cyclophosphamide (CY), a known immunosuppressant, were administered to adult mallards (Anas platyrhynchos) to determine if a resultant decrease in resistance to a normally sub-lethal strain of duck plague virus would occur, and induce mortality in these birds. Deathmore » occurred in birds given CY only, and in birds given virus and CY, but not in those given virus only. There was significantly greater mortality and more rapid deaths in the duck plague virus-infected groups than in groups receiving only the immunosuppressant. A positively correlated dose-response effect was observed with CY mortalities, irrespective of virus exposure. A fuel oil and a crude oil, common environmental contaminants with immunosuppressive capabilities, were tested to determine if they could produce an effect similar to that of CY. Following 28 days of oral oil administration, the birds were challenged with a sub-lethal dose of duck plague virus. No alteration in resistance to the virus (as measured by mortality) was observed, except in the positive CY control group.« less
Biodegradation of Tributyltin (TBT) by Extremophile Bacteria from Atacama Desert and Speciation of Tin By-products.

PubMed

Yáñez, Jorge; Riffo, Paula; Santander, Paola; Mansilla, Héctor D; Mondaca, María Angélica; Campos, Víctor; Amarasiriwardena, Dulasiri

2015-07-01

Biodegradation of tributyltin (TBT) by four tin resistant Gram negative bacteria isolated from extremely contaminated river sediments in the Atacama Desert in Chile was studied. Moraxella osloensis showed the greatest resistance and degradation capability of TBT, producing less toxic by-products, such as dibutyltin (DBT) and inorganic tin. In 7 days, approximately 80 % of TBT degradation was achieved, generating close to 20 % of DBT as degradation product. The degradation rate constant (k) was 0.022 [day(-1)] and TBT half-life (t1/2) in culture was 4.3 days. Debutylation is stated a probable mechanism of TBT degradation.
Endophytes and their Potential to Deal with Co-contamination of Organic Contaminants (Toluene) and Toxic Metals (Nickel) during Phytoremediation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weyens, N.; van der Lelie, D.; Truyens, S.

The aim was to investigate if engineered endophytes that are capable of degrading organic contaminants, and deal with or ideally improve uptake and translocation of toxic metals, can improve phytoremediation of mixed organic-metal pollution. As a model system, yellow lupine was inoculated with the endophyte Burkholderia cepacia VM1468 possessing (a) the pTOM-Bu61 plasmid, coding for constitutive toluene/TCE degradation, and (b) the chromosomally inserted ncc-nre Ni resistance/sequestration system. As controls, plants were inoculated with B. vietnamiensis BU61 (pTOM-Bu61) and B. cepacia BU72 (containing the ncc-nre Ni resistance/sequestration system). Plants were exposed to mixes of toluene and Ni. Only inoculation with B.more » cepacia VM1468 resulted in decreased Ni and toluene phytotoxicity, as measured by a protective effect on plant growth and decreased activities of enzymes involved in antioxidative defence (catalase, guaiacol peroxidase, superoxide dismutase) in the roots. Besides, plants inoculated with B. cepacia VM1468 and B. vietnamiensis BU61 released less toluene through the leaves than non-inoculated plants and those inoculated with B. cepacia BU72. Ni-uptake in roots was slightly increased for B. cepacia BU72 inoculated plants. These results indicate that engineered endophytes have the potential to assist their host plant to deal with co-contamination of toxic metals and organic contaminants during phytoremediation.« less
Microbial Functional Gene Diversity Predicts Groundwater Contamination and Ecosystem Functioning

PubMed Central

Zhang, Ping; Wu, Linwei; Rocha, Andrea M.; Shi, Zhou; Wu, Bo; Qin, Yujia; Wang, Jianjun; Yan, Qingyun; Curtis, Daniel; Ning, Daliang; Van Nostrand, Joy D.; Wu, Liyou; Watson, David B.; Adams, Michael W. W.; Alm, Eric J.; Adams, Paul D.; Arkin, Adam P.

2018-01-01

ABSTRACT Contamination from anthropogenic activities has significantly impacted Earth’s biosphere. However, knowledge about how environmental contamination affects the biodiversity of groundwater microbiomes and ecosystem functioning remains very limited. Here, we used a comprehensive functional gene array to analyze groundwater microbiomes from 69 wells at the Oak Ridge Field Research Center (Oak Ridge, TN), representing a wide pH range and uranium, nitrate, and other contaminants. We hypothesized that the functional diversity of groundwater microbiomes would decrease as environmental contamination (e.g., uranium or nitrate) increased or at low or high pH, while some specific populations capable of utilizing or resistant to those contaminants would increase, and thus, such key microbial functional genes and/or populations could be used to predict groundwater contamination and ecosystem functioning. Our results indicated that functional richness/diversity decreased as uranium (but not nitrate) increased in groundwater. In addition, about 5.9% of specific key functional populations targeted by a comprehensive functional gene array (GeoChip 5) increased significantly (P < 0.05) as uranium or nitrate increased, and their changes could be used to successfully predict uranium and nitrate contamination and ecosystem functioning. This study indicates great potential for using microbial functional genes to predict environmental contamination and ecosystem functioning. PMID:29463661
Contamination of Canadian private drinking water sources with antimicrobial resistant Escherichia coli.

PubMed

Coleman, Brenda L; Louie, Marie; Salvadori, Marina I; McEwen, Scott A; Neumann, Norman; Sibley, Kristen; Irwin, Rebecca J; Jamieson, Frances B; Daignault, Danielle; Majury, Anna; Braithwaite, Shannon; Crago, Bryanne; McGeer, Allison J

2013-06-01

Surface and ground water across the world, including North America, is contaminated with bacteria resistant to antibiotics. The consumption of water contaminated with antimicrobial resistant Escherichia coli (E. coli) has been associated with the carriage of resistant E. coli in people who drink it. To describe the proportion of drinking water samples submitted from private sources for bacteriological testing that were contaminated with E. coli resistant to antibiotics and to determine risk factors for the contamination of these water sources with resistant and multi-class resistant E. coli. Water samples submitted for bacteriological testing in Ontario and Alberta Canada were tested for E. coli contamination, with a portion of the positive isolates tested for antimicrobial resistance. Households were invited to complete questionnaires to determine putative risk factors for well contamination. Using multinomial logistic regression, the risk of contamination with E. coli resistant to one or two classes of antibiotics compared to susceptible E. coli was higher for shore wells than drilled wells (odds ratio [OR] 2.8) and higher for farms housing chickens or turkeys (OR 3.0) than properties without poultry. The risk of contamination with multi-class resistant E. coli (3 or more classes) was higher if the properties housed swine (OR 5.5) or cattle (OR 2.2) than properties without these livestock and higher if the wells were located in gravel (OR 2.4) or clay (OR 2.1) than in loam. Housing livestock on the property, using a shore well, and having a well located in gravel or clay soil increases the risk of having antimicrobial resistant E. coli in E. coli contaminated wells. To reduce the incidence of water borne disease and the transmission of antimicrobial resistant bacteria, owners of private wells need to take measures to prevent contamination of their drinking water, routinely test their wells for contamination, and use treatments that eliminate bacteria. Copyright © 2013 Elsevier Ltd. All rights reserved.
Durability Challenges for Next Generation of Gas Turbine Engine Materials

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

2012-01-01

Aggressive fuel burn and carbon dioxide emission reduction goals for future gas turbine engines will require higher overall pressure ratio, and a significant increase in turbine inlet temperature. These goals can be achieved by increasing temperature capability of turbine engine hot section materials and decreasing weight of fan section of the engine. NASA is currently developing several advanced hot section materials for increasing temperature capability of future gas turbine engines. The materials of interest include ceramic matrix composites with 1482 - 1648 C temperature capability, advanced disk alloys with 815 C capability, and low conductivity thermal barrier coatings with erosion resistance. The presentation will provide an overview of durability challenges with emphasis on the environmental factors affecting durability for the next generation of gas turbine engine materials. The environmental factors include gaseous atmosphere in gas turbine engines, molten salt and glass deposits from airborne contaminants, impact from foreign object damage, and erosion from ingestion of small particles.
Microbial Functional Gene Diversity Predicts Groundwater Contamination and Ecosystem Functioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Zhili; Zhang, Ping; Wu, Linwei

Contamination from anthropogenic activities has significantly impacted Earth’s biosphere. However, knowledge about how environmental contamination affects the biodiversity of groundwater microbiomes and ecosystem functioning remains very limited. Here, we used a comprehensive functional gene array to analyze groundwater microbiomes from 69 wells at the Oak Ridge Field Research Center (Oak Ridge, TN), representing a wide pH range and uranium, nitrate, and other contaminants. We hypothesized that the functional diversity of groundwater microbiomes would decrease as environmental contamination (e.g., uranium or nitrate) increased or at low or high pH, while some specific populations capable of utilizing or resistant to those contaminantsmore » would increase, and thus, such key microbial functional genes and/or populations could be used to predict groundwater contamination and ecosystem functioning. Our results indicated that functional richness/diversity decreased as uranium (but not nitrate) increased in groundwater. In addition, about 5.9% of specific key functional populations targeted by a comprehensive functional gene array (GeoChip 5) increased significantly (P < 0.05) as uranium or nitrate increased, and their changes could be used to successfully predict uranium and nitrate contamination and ecosystem functioning. Here, this study indicates great potential for using microbial functional genes to predict environmental contamination and ecosystem functioning.« less
Microbial Functional Gene Diversity Predicts Groundwater Contamination and Ecosystem Functioning

DOE PAGES

He, Zhili; Zhang, Ping; Wu, Linwei; ...

2018-02-20

Contamination from anthropogenic activities has significantly impacted Earth’s biosphere. However, knowledge about how environmental contamination affects the biodiversity of groundwater microbiomes and ecosystem functioning remains very limited. Here, we used a comprehensive functional gene array to analyze groundwater microbiomes from 69 wells at the Oak Ridge Field Research Center (Oak Ridge, TN), representing a wide pH range and uranium, nitrate, and other contaminants. We hypothesized that the functional diversity of groundwater microbiomes would decrease as environmental contamination (e.g., uranium or nitrate) increased or at low or high pH, while some specific populations capable of utilizing or resistant to those contaminantsmore » would increase, and thus, such key microbial functional genes and/or populations could be used to predict groundwater contamination and ecosystem functioning. Our results indicated that functional richness/diversity decreased as uranium (but not nitrate) increased in groundwater. In addition, about 5.9% of specific key functional populations targeted by a comprehensive functional gene array (GeoChip 5) increased significantly (P < 0.05) as uranium or nitrate increased, and their changes could be used to successfully predict uranium and nitrate contamination and ecosystem functioning. Here, this study indicates great potential for using microbial functional genes to predict environmental contamination and ecosystem functioning.« less
Multiple antibiotic resistant Escherichia coli from a tropical rain forest stream

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carrasco, C.E.; Alvarez, H.J.; Ortiz, N.

1988-12-31

High densities of fecal coliforms were obtained from a pristine site and sewage contaminated site in a tropical rain forest watershed in Puerto Rico. Confirmation of fecal coliform isolates as Escherichia coli was significantly lower than for temperate waters. Antibiotic resistance and multiple antibiotic resistance were common for isolates at both sites; however, the site receiving sewage effluent had a greater proportion of multiple antibiotic resistant isolates. R. plasmids were recovered from 4 MAR isolates, 2 from each site. All recovered plasmids were approximately 1 kilobase. The recovered plasmid were also capable of transforming E. coli HB101 in vitro. Themore » high concentrations of enterobacteriaceae, small R-plasmid size, R-plasmid transformability, and long term survival of fecal origin bacteria in tropical freshwater environments give increasing importance to adequate sewage treatment, and better indicator monitoring methods for tropical areas.« less
The effect of contaminant on skid resistance of pavement surface

NASA Astrophysics Data System (ADS)

Lubis, A. S.; Muis, Z. A.; Gultom, E. M.

2018-03-01

Skid resistance of the pavement surface is the force generated by the movement of the wheels of the vehicle on the surface of the pavement. Contaminants are materials that cover the surface of the pavement affecting the skid resistance of the pavement surface. The contaminant acts as a coating interface or direct contact of the pavement surface with the wheels of the vehicle which can cause adverse effects, such as the decreasing value of skid resistance of the pavement surface. This study aims to analyze the effect of some types of contaminants on skid resistance of pavement surfaces. The contaminants that used in this study were water, sand, salt, and lubricating oil. The study was conducted by direct testing on two types of pavement: flexible pavement and rigid pavement. The measurements of the skid resistance were made using the British Pendulum Tester with British Pendulum Number for two conditions: before and after the pavement surface was covered with contaminants. The results showed that there was a contaminant effect on skid resistance of pavement surface. Skid resistance of pavement surfaces decreased after the contaminants were covered in water, sand, salt, and lubricant by 20.1%, 22.8%, 37.1% and 50.5% respectively.
Metal resistance in populations of red maple (Acer rubrum L.) and white birch (Betula papyrifera Marsh.) from a metal-contaminated region and neighbouring non-contaminated regions.

PubMed

Kirkey, Fallon M; Matthews, Jennifer; Ryser, Peter

2012-05-01

Metal resistance in populations of Acer rubrum and Betula papyrifera in the industrially contaminated region of Sudbury, Ontario, was compared with resistance in populations from neighbouring uncontaminated regions. In two one-season experiments, seedlings were grown outdoors on contaminated (mainly Cu, Ni) and uncontaminated substrates. Sudbury populations of both species responded less to contamination than populations from uncontaminated regions. In A. rubrum this difference was small. For both species, Sudbury plants were smaller when grown on uncontaminated substrate. B. papyrifera from Sudbury grew better on contaminated substrate than the other populations. There is indication of variation in metal resistance within the populations from the non-contaminated regions. The data shows that trees may develop adaptive resistance to heavy metals, but the low degree of resistance indicates that the development of such resistances are slower than observed for herbaceous species with shorter generation times. Copyright © 2012 Elsevier Ltd. All rights reserved.
Enterotoxigenicity and Antimicrobial Resistance of Staphylococcus aureus Isolated from Retail Food in China

PubMed Central

Wang, Wei; Baloch, Zulqarnain; Jiang, Tao; Zhang, Cunshan; Peng, Zixin; Li, Fengqin; Fanning, Séamus; Ma, Aiguo; Xu, Jin

2017-01-01

Staphylococcus aureus is one of the most common causes of zoonotic agent in the world, which are attributable to the contamination of food with enterotoxins. In this study, a total of 1,150 S. aureus isolates were cultured from 27,000 retail foods items from 203 cities of 24 provinces in China in 2015 and were test for antimicrobial susceptibility. Additionally, the role of the genes responsible for the staphylococcal enterotoxins (SEA to SEE), methicillin resistance (mecA) and the toxigenic capabilities were also assessed. The results showed that 4.3% retail foods were contaminated with S. aureus, and 7.9% retail foods isolates were mecA positive. Some 97.6% of S. aureus isolates were resistant to at least one antimicrobial compound, and 57.5% of these were multi drug resistant (MDR). Resistance to penicillin (83.7%, 963/1,150), was common, followed by linezolid (67.7%, 778/1,150) and erythromycin (52.1%, 599/1,150). The isolates cultured from raw meats showed high levels of resistant to tetracycline (42.8%), ciprofloxacin (17.4%), and chloramphenicol (12.0%) and expressed a MDR phenotype (62.4%). A total of 29.7% S. aureus isolates harbored the classical SEs genes (sea, seb, sec, and sed). The sea and seb genes were the most frequent SEs genes detected. Of note, 22% of the SEs genes positive S. aureus harbored two or three SEs genes, and 16 isolates were confirmed with the capacity to simultaneously produce two or three enterotoxin types. Moreover, nearly 50% of the MRSA isolates were positive for at least one SE gene in this study. Therefore, it is important to monitor the antimicrobial susceptibility and enterotoxigenicity of MDR S. aureus and MRSA in the food chain and to use these data to develop food safety measures, designed to reduce the contamination and transmission of this bacterium. PMID:29209290
Enterotoxigenicity and Antimicrobial Resistance of Staphylococcus aureus Isolated from Retail Food in China.

PubMed

Wang, Wei; Baloch, Zulqarnain; Jiang, Tao; Zhang, Cunshan; Peng, Zixin; Li, Fengqin; Fanning, Séamus; Ma, Aiguo; Xu, Jin

2017-01-01

Staphylococcus aureus is one of the most common causes of zoonotic agent in the world, which are attributable to the contamination of food with enterotoxins. In this study, a total of 1,150 S. aureus isolates were cultured from 27,000 retail foods items from 203 cities of 24 provinces in China in 2015 and were test for antimicrobial susceptibility. Additionally, the role of the genes responsible for the staphylococcal enterotoxins (SEA to SEE), methicillin resistance ( mecA ) and the toxigenic capabilities were also assessed. The results showed that 4.3% retail foods were contaminated with S. aureus , and 7.9% retail foods isolates were mecA positive. Some 97.6% of S. aureus isolates were resistant to at least one antimicrobial compound, and 57.5% of these were multi drug resistant (MDR). Resistance to penicillin (83.7%, 963/1,150), was common, followed by linezolid (67.7%, 778/1,150) and erythromycin (52.1%, 599/1,150). The isolates cultured from raw meats showed high levels of resistant to tetracycline (42.8%), ciprofloxacin (17.4%), and chloramphenicol (12.0%) and expressed a MDR phenotype (62.4%). A total of 29.7% S. aureus isolates harbored the classical SEs genes ( sea, seb, sec , and sed ). The sea and seb genes were the most frequent SEs genes detected. Of note, 22% of the SEs genes positive S. aureus harbored two or three SEs genes, and 16 isolates were confirmed with the capacity to simultaneously produce two or three enterotoxin types. Moreover, nearly 50% of the MRSA isolates were positive for at least one SE gene in this study. Therefore, it is important to monitor the antimicrobial susceptibility and enterotoxigenicity of MDR S. aureus and MRSA in the food chain and to use these data to develop food safety measures, designed to reduce the contamination and transmission of this bacterium.
Microlith Based Sorber for Removal of Environmental Contaminants

NASA Technical Reports Server (NTRS)

Roychoudhury, S.; Perry, J.

2004-01-01

The development of energy efficient, lightweight sorption systems for removal of environmental contaminants in space flight applications is an area of continuing interest to NASA. The current CO2 removal system on the International Space Station employs two pellet bed canisters of 5A molecular sieve that alternate between regeneration and sorption. A separate disposable charcoal bed removes trace contaminants. An alternative technology has been demonstrated using a sorption bed consisting of metal meshes coated with a sorbent, trademarked and patented as Microlith by Precision Combustion, Inc. (PCI); thesemeshes have the potential for direct electrical heating for this application. This allows the bed to be regenerable via resistive heating and offers the potential for shorter regeneration times, reduced power requirement, and net energy savings vs. conventional systems. The capability of removing both CO2 and trace contaminants within the same bed has also been demonstrated. Thus, the need for a separate trace contaminant unit is eliminated resulting in an opportunity for significant weight savings. Unlike the charcoal bed, zeolites for trace contaminant removal are amenable to periodic regeneration. This paper describes the design and performance of a prototype sorber device for simultaneous CO2 and trace contarninant removal and its attendant weight and energy savings.
Experimental study of the complex resistivity and dielectric constant of chrome-contaminated soil

NASA Astrophysics Data System (ADS)

Liu, Haorui; Yang, Heli; Yi, Fengyan

2016-08-01

Heavy metals such as arsenic and chromium often contaminate soils near industrialized areas. Soil samples, made with different water content and chromate pollutant concentrations, are often needed to test soil quality. Because complex resistivity and complex dielectric characteristics of these samples need to be measured, the relationship between these measurement results and chromium concentration as well as water content was studied. Based on soil sample observations, the amplitude of the sample complex resistivity decreased with an increase of contamination concentration and water content. The phase of complex resistivity takes on a tendency of initially decrease, and then increase with the increasing of contamination concentration and water content. For a soil sample with the same resistivity, the higher the amplitude of complex resistivity, the lower the water content and the higher the contamination concentration. The real and imaginary parts of the complex dielectric constant increase with an increase in contamination concentration and water content. Note that resistivity and complex resistivity methods are necessary to adequately evaluate pollution at various sites.
Identification, characterization, and analysis of hydraulically conductive fractures in granitic basement rocks, Millville, Massachusetts

USGS Publications Warehouse

Paillet, Frederick L.; Ollila, P.W.

1994-01-01

A suite of geophysical logs designed to identify and characterize fractures and water production in fractures was run in six bedrock boreholes at a ground-water contamination site near the towns of Millville and Uxbridge in south-central Massachusetts. The geophysical logs used in this study included conventional gamma, single-point resistance, borehole fluid resistivity, caliper, spontaneous potential, and temperature; and the borehole televiewer and heat-pulse flowmeter, which are not usually used to log bedrock water-supply wells. Downward flow under ambient hydraulic-head conditions was measured in three of the boreholes at the site, and the profile of fluid column resistivity inferred from the logs indicated downward flow in all six boreholes. Steady injection tests at about 1.0 gallon per minute were used to identify fractures capable of conducting flow under test conditions. Sixteen of 157 fracturesidentified on the televiewer logs and interpreted as permeable fractures in the data analysis were determined to conduct flow under ambient hydraulic-head conditions or during injection. Hydraulic-head monitoring in the bedrock boreholes indicated a consistent head difference between the upper and lower parts of the boreholes. This naturally occurring hydraulic-head condition may account, in part, for the transport of contaminants from the overlying soil into the bedrock aquifer. The downward flow may also account for the decrease in contaminant concentrations found in some boreholes after routine use of the boreholes as water-supply wells was discontinued.
Occurrence and Control of Tularemia in Drinking Water ...

EPA Pesticide Factsheets

Journal Article This review article will focus on tularemia acquired from contaminated drinking water and the adequacy of control measures for preventing waterborne transmission. Contaminated drinking water can serve as a vehicle for the spread of tularemia. Disease occurrence has been most commonly associated with untreated community and domestic water supplies. F. tularensis is of interest both from the standpoint of natural occurring waterborne outbreaks and in regards to its potential use as a bio-threat organism. The organism can persist in the aquatic environment and methods exist for detection in water. While capable of being inactivated by commonly used drinking water disinfectants, F. tularensis does exhibit an increased resistance to chlorination in comparison to other waterborne vegetative bacterial pathogens.
Contamination control in hybrid microelectronic modules. Part 2: Selection and evaluation of coating materials

NASA Technical Reports Server (NTRS)

Himmel, R. P.

1975-01-01

The selection, test, and evaluation of organic coating materials for contamination control in hybrid circuits is reported. The coatings were evaluated to determine their suitability for use as a conformal coating over the hybrid microcircuit (including chips and wire bonds) inside a hermetically sealed package. Evaluations included ease of coating application and repair and effect on thin film and thick film resistors, beam leads, wire bonds, transistor chips, and capacitor chips. The coatings were also tested for such properties as insulation resistance, voltage breakdown strength, and capability of immobilizing loose particles inside the packages. The selected coatings were found to be electrically, mechanically, and chemically compatible with all components and materials normally used in hybrid microcircuits.
Isolation and characterization of aerobic culturable arsenic-resistant bacteria from surfacewater and groundwater of Rautahat District, Nepal.

PubMed

Shakya, S; Pradhan, B; Smith, L; Shrestha, J; Tuladhar, S

2012-03-01

Arsenic (As) contamination of groundwater is a serious Environmental Health Management issue of drinking water sources especially in Terai region of Nepal. Many studies have reported that due to natural abundance of arsenic in the environment, various bacteria have developed different resistance mechanisms for arsenic compound. In this study, the culturable arsenic-resistant bacteria indigenous to surfacewater as well as groundwater from Rautahat District of Nepal were randomly isolated by standard plate count method on the basis of viable growth on plate count agar amended with arsenate ranging from 0, 0.5, 10, 40, 80 to 160 milligram per liter (mg/l). With respect to the morphological and biochemical tests, nine morphologically distinct potent arsenate tolerant bacteria showed relatedness with Micrococcus varians, Micrococcus roseus, Micrococcus luteus, Pseudomonas maltophilia, Pseudomonas sp., Vibrio parahaemolyticus, Bacillus cereus, Bacillus smithii 1 and Bacillus smithii 2. The isolates were capable of tolerating more than 1000 mg/l of arsenate and 749 mg/l of arsenite. Likewise, bioaccumulation capability was highest with M. roseus (85.61%) and the least with B. smithii (47.88%) indicating the potential of the organisms in arsenic resistance and most probably in bioremediation. Copyright © 2011 Elsevier Ltd. All rights reserved.
Contamination of X-ray Cassettes with Methicillin-resistant Staphylococcus aureus and Methicillin-resistant Staphylococcus haemolyticus in a Radiology Department

PubMed Central

Kim, Han-Sung; Park, Ji-Young; Koo, Hyun-Sook; Choi, Chul-Sun; Song, Wonkeun; Cho, Hyoun Chan; Lee, Kyu Man

2012-01-01

Background We performed surveillance cultures of the surfaces of X-ray cassettes to assess contamination with methicillin-resistant Staphylococcus aureus (MRSA). Methods The surfaces of 37 X-ray cassettes stored in a radiology department were cultured using mannitol salt agar containing 6 µg/mL oxacillin. Suspected methicillin-resistant staphylococcal colonies were isolated and identified by biochemical testing. Pulsed-field gel electrophoresis (PFGE) analysis was performed to determine the clonal relationships of the contaminants. Results Six X-ray cassettes (16.2%) were contaminated with MRSA. During the isolation procedure, we also detected 19 X-ray cassettes (51.4%) contaminated with methicillin-resistant Staphylococcus haemolyticus (MRSH), identified as yellow colonies resembling MRSA on mannitol salt agar. PFGE analysis of the MRSA and MRSH isolates revealed that most isolates of each organism were identical or closely related to each other, suggesting a common source of contamination. Conclusions X-ray cassettes, which are commonly in direct contact with patients, were contaminated with MRSA and MRSH. In hospital environments, contaminated X-ray cassettes may serve as fomites for methicillin-resistant staphylococci. PMID:22563556

Contamination of X-ray cassettes with methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus haemolyticus in a radiology department.

PubMed

Kim, Jae-Seok; Kim, Han-Sung; Park, Ji-Young; Koo, Hyun-Sook; Choi, Chul-Sun; Song, Wonkeun; Cho, Hyoun Chan; Lee, Kyu Man

2012-05-01

We performed surveillance cultures of the surfaces of X-ray cassettes to assess contamination with methicillin-resistant Staphylococcus aureus (MRSA). The surfaces of 37 X-ray cassettes stored in a radiology department were cultured using mannitol salt agar containing 6 µg/mL oxacillin. Suspected methicillin-resistant staphylococcal colonies were isolated and identified by biochemical testing. Pulsed-field gel electrophoresis (PFGE) analysis was performed to determine the clonal relationships of the contaminants. Six X-ray cassettes (16.2%) were contaminated with MRSA. During the isolation procedure, we also detected 19 X-ray cassettes (51.4%) contaminated with methicillin-resistant Staphylococcus haemolyticus (MRSH), identified as yellow colonies resembling MRSA on mannitol salt agar. PFGE analysis of the MRSA and MRSH isolates revealed that most isolates of each organism were identical or closely related to each other, suggesting a common source of contamination. X-ray cassettes, which are commonly in direct contact with patients, were contaminated with MRSA and MRSH. In hospital environments, contaminated X-ray cassettes may serve as fomites for methicillin-resistant staphylococci.
Process optimization for particle removal on blank chrome mask plates in preparation for resist application

NASA Astrophysics Data System (ADS)

Osborne, Stephen; Smith, Eryn; Woster, Eric; Pelayo, Anthony

2002-03-01

As integrated circuits require smaller lines to provide the memory and processing capability for tomorrow's marketplace, the photomask industry is adopting higher contrast resists to improve photomask lithography. Photomask yield for several high-contrast resist recipes may be improved by coating masks at the mask shop. When coating at a mask shop, an effective method is available that uses coat/bake cluster tools to ensure blanks are clean prior to coating. Many high-contrast resists are available, and some are more susceptible to time-dependent performance factors than conventional resists. One of these factors is the time between coating and writing. Although future methods may reduce the impact of this factor, one current trend is to reduce this time by coating plates at the mask shop just prior to writing. Establishing an effective process to clean blanks prior to coating is necessary for product quality control and is a new task that is critical for maskmakers who previously purchased mask plates but have decided to begin coating them within their facility. This paper provides a strategy and method to be used within coat/bake cluster tools to remove particle contamination from mask blanks. The process uses excimer-UV ionizing radiation and ozone to remove organic contaminants, and then uses a wet process combined with megasonic agitation, surfactant, and spin forces. Megasonic agitation with surfactant lifts up particles, while the convective outflow of water enhances centripetal shear without accumulating harmful charge.
Embedding intensity image into a binary hologram with strong noise resistant capability

NASA Astrophysics Data System (ADS)

Zhuang, Zhaoyong; Jiao, Shuming; Zou, Wenbin; Li, Xia

2017-11-01

A digital hologram can be employed as a host image for image watermarking applications to protect information security. Past research demonstrates that a gray level intensity image can be embedded into a binary Fresnel hologram by error diffusion method or bit truncation coding method. However, the fidelity of the retrieved watermark image from binary hologram is generally not satisfactory, especially when the binary hologram is contaminated with noise. To address this problem, we propose a JPEG-BCH encoding method in this paper. First, we employ the JPEG standard to compress the intensity image into a binary bit stream. Next, we encode the binary bit stream with BCH code to obtain error correction capability. Finally, the JPEG-BCH code is embedded into the binary hologram. By this way, the intensity image can be retrieved with high fidelity by a BCH-JPEG decoder even if the binary hologram suffers from serious noise contamination. Numerical simulation results show that the image quality of retrieved intensity image with our proposed method is superior to the state-of-the-art work reported.
Evaluating specificity of sequential extraction for chemical forms of lead in artificially-contaminated and field-contaminated soils.

PubMed

Tai, Yiping; McBride, Murray B; Li, Zhian

2013-03-30

In the present study, we evaluated a commonly employed modified Bureau Communautaire de Référence (BCR test) 3-step sequential extraction procedure for its ability to distinguish forms of solid-phase Pb in soils with different sources and histories of contamination. When the modified BCR test was applied to mineral soils spiked with three forms of Pb (pyromorphite, hydrocerussite and nitrate salt), the added Pb was highly susceptible to dissolution in the operationally-defined "reducible" or "oxide" fraction regardless of form. When three different materials (mineral soil, organic soil and goethite) were spiked with soluble Pb nitrate, the BCR sequential extraction profiles revealed that soil organic matter was capable of retaining Pb in more stable and acid-resistant forms than silicate clay minerals or goethite. However, the BCR sequential extraction for field-collected soils with known and different sources of Pb contamination was not sufficiently discriminatory in the dissolution of soil Pb phases to allow soil Pb forms to be "fingerprinted" by this method. It is concluded that standard sequential extraction procedures are probably not very useful in predicting lability and bioavailability of Pb in contaminated soils. Copyright © 2013 Elsevier B.V. All rights reserved.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Inglese, Alessandro, E-mail: alessandro.inglese@aalto.fi; Savin, Hele; Lindroos, Jeanette

Copper is a harmful metal impurity that significantly impacts the performance of silicon-based devices if present in active regions. In this contribution, we propose a fast method consisting of simultaneous illumination and annealing for the detection of copper contamination in p-type silicon. Our results show that, within minutes, such method is capable of producing a significant reduction of the minority carrier lifetime. A spatial distribution map of copper contamination can then be obtained through the lifetime values measured before and after degradation. In order to separate the effect of the light-activated copper defects from the other metastable complexes in lowmore » resistivity Cz-silicon, we carried out a dark anneal at 200 °C, which is known to fully recover the boron-oxygen defect. Similar to the boron-oxygen behavior, we show that the dark anneal also recovers the copper defects. However, the recovery is only partial and it can be used to identify the possible presence of copper contamination.« less
Possible Extent and Depth of Salt Contamination in Ground Water Using Geophysical Techniques, Red River Aluminum Site, Stamps, Arkansas, April 2003

USGS Publications Warehouse

Stanton, Gregory P.; Kress, Wade; Hobza, Christopher M.; Czarnecki, John B.

2003-01-01

A surface-geophysical investigation of the Red River Aluminum site at Stamps, Arkansas, was conducted in cooperation with the Arkansas Department of Environmental Quality to determine the possible extent and depth of saltwater contamination. Water-level measurements indicate the distance to water level below land surface ranges from about 1.2 to 3.9 feet (0.37 to 1.19 meters) in shallow monitor wells and about 10.5 to 17.1 feet (3.20 to 5.21 meters) in deeper monitoring wells. The two-dimensional, direct-current resistivity method identified resistivities less than 5 ohm-meters which indicated possible areas of salt contamination occurring in near-surface or deep subsurface ground water along four resistivity lines within the site. One line located east of the site yielded data that demonstrated no effect of salt contamination. Sections from two of the five data sets were modeled. The input model grids were created on the basis of the known geology and the results and interpretations of borehole geophysical data. The clay-rich Cook Mountain Formation is modeled as 25 ohm-meters and extends from 21 meters (68.9 feet) below land surface to the bottom of the model (about 52 meters (170.6 feet)). The models were used to refine interpretation of the resistivity data and to determine extent of saltwater contamination and depth to the Cook Mountain Formation. Data from the resistivity lines indicate both near-surface and subsurface saltwater contamination. The near-surface contamination appears as low resistivity (less than 5 ohm-meters) on four of the five resistivity lines, extending up to 775 meters (2,542.8 feet) horizontally in a line that traverses the entire site south to north. Model resistivity data indicate that the total depth of saltwater contamination is about 18 meters (59 feet) below land surface. Data from four resistivity lines identified areas containing low resistivity anomalies interpreted as possible salt contamination. A fifth line located just east of the site showed no saltwater contamination.
Accurate modeling and inversion of electrical resistivity data in the presence of metallic infrastructure with known location and dimension

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Timothy C.; Wellman, Dawn M.

2015-06-26

Electrical resistivity tomography (ERT) has been widely used in environmental applications to study processes associated with subsurface contaminants and contaminant remediation. Anthropogenic alterations in subsurface electrical conductivity associated with contamination often originate from highly industrialized areas with significant amounts of buried metallic infrastructure. The deleterious influence of such infrastructure on imaging results generally limits the utility of ERT where it might otherwise prove useful for subsurface investigation and monitoring. In this manuscript we present a method of accurately modeling the effects of buried conductive infrastructure within the forward modeling algorithm, thereby removing them from the inversion results. The method ismore » implemented in parallel using immersed interface boundary conditions, whereby the global solution is reconstructed from a series of well-conditioned partial solutions. Forward modeling accuracy is demonstrated by comparison with analytic solutions. Synthetic imaging examples are used to investigate imaging capabilities within a subsurface containing electrically conductive buried tanks, transfer piping, and well casing, using both well casings and vertical electrode arrays as current sources and potential measurement electrodes. Results show that, although accurate infrastructure modeling removes the dominating influence of buried metallic features, the presence of metallic infrastructure degrades imaging resolution compared to standard ERT imaging. However, accurate imaging results may be obtained if electrodes are appropriately located.« less
Spacelab baseline ECS trace contaminant removal test program

NASA Technical Reports Server (NTRS)

Ray, C. D.; Stanley, J. B.

1977-01-01

An estimate of the Spacelab Baseline Environmental Control System's contaminated removal capability was required to allow determination of the need for a supplemental trace contaminant removal system. Results from a test program to determine this removal capability are presented.
Delineation of contaminant plume for an inorganic contaminated site using electrical resistivity tomography: comparison with direct-push technique.

PubMed

Liao, Qing; Deng, Yaping; Shi, Xiaoqing; Sun, Yuanyuan; Duan, Weidong; Wu, Jichun

2018-03-03

Precise delineation of contaminant plume distribution is essential for effective remediation of contaminated sites. Traditional in situ investigation methods like direct-push (DP) sampling are accurate, but are usually intrusive and costly. Electrical resistivity tomography (ERT) method, as a non-invasive geophysical technique to map spatiotemporal changes in resistivity of the subsurface, is becoming increasingly popular in environmental science. However, the resolution of ERT for delineation of contaminant plumes still remains controversial. In this study, ERT and DP technique were both conducted at a real inorganic contaminated site. The reliability of the ERT method was validated by the direct comparisons of their investigation results that the resistivity acquired by ERT method is in accordance with the total dissolved solid concentration in groundwater and the overall variation of the total iron content in soil obtained by DP technique. After testifying the applicability of ERT method for contaminant identification, the extension of contaminant plume at the study site was revealed by supplementary ERT surveys conducted subsequently in the surrounding area of the contaminant source zone.
Breeding aflatoxin-resistant maize lines using recent advances in technologies - a review.

PubMed

Brown, Robert L; Menkir, Abebe; Chen, Zhi-Yuan; Bhatnagar, Deepak; Yu, Jiujiang; Yao, Haibo; Cleveland, Thomas E

2013-01-01

Aflatoxin contamination caused by Aspergillus flavus infection of corn is a significant and chronic threat to corn being used as food or feed. Contamination of crops at levels of 20 ng g(-1) or higher (as regulated by the USFDA) by this toxin and potent carcinogen makes the crop unsalable, resulting in a significant economic burden on the producer. This review focuses on elimination of this contamination in corn which is a major US crop and the basis of many products. Corn is also "nature's example" of a crop containing heritable resistance to aflatoxin contamination, thereby serving as a model for achieving resistance to aflatoxin contamination in other crops as well. This crop is the largest production grain crop worldwide, providing food for billions of people and livestock and critical feedstock for production of biofuels. In 2011, the economic value of the US corn crop was US$76 billion, with US growers producing an estimated 12 billion bushels, more than one-third of the world's supply. Thus, the economics and significance of corn as a food crop and the threat to food safety due to aflatoxin contamination of this major food crop have prompted the many research efforts in many parts of the world to identify resistance in corn to aflatoxin contamination. Plant breeding and varietal selection has been used as a tool to develop varieties resistance to disease. This methodology has been employed in defining a few corn lines that show resistance to A. flavus invasion; however, no commercial lines have been marketed. With the new tools of proteomics and genomics, identification of resistance mechanisms, and rapid resistance marker selection methodologies, there is an increasing possibility of finding significant resistance in corn, and in understanding the mechanism of this resistance.
Isolation and characterization of bacteria from mercury contaminated sites in Rio Grande do Sul, Brazil, and assessment of methylmercury removal capability of a Pseudomonas putida V1 strain.

PubMed

Cabral, Lucélia; Giovanella, Patrícia; Gianello, Clésio; Bento, Fátima Menezes; Andreazza, Robson; Camargo, Flávio Anastácio Oliveira

2013-06-01

Methylmercury (MeHg) is one of the most dangerous heavy metal for living organisms that may be found in environment. Given the crescent industrialization of Brazil and considering that mercury is a residue of several industrial processes, there is an increasing need to encounter and develop remediation approaches of mercury contaminated sites. The aim of this study was to isolate and characterize methylmercury resistant bacteria from soils and sludge sewage from Rio Grande do Sul, Brazil. Sixteen bacteria were isolated from these contaminated sites and some isolates were highly resistant to methylmercury (>8.7 μM). All the isolates were identified by 16S rDNA. Pseudomonas putida V1 was able to volatilize approximately 90 % of methylmercury added to growth media and to resist to copper, lead, nickel, chromate, zinc, cobalt, manganese and barium. In the presence of high concentrations of methylmercury (12 μM), cell growth was limited, but P. putida V1 was still able to remove up to 29 % of this compound from culture medium. This bacterium removed an average of 77 % of methylmercury from culture medium with pH in the range 4.0-6.0. In addition, methylmercury was efficiently removed (>80 %) in temperature of 21-25 °C. Polymerase chain reactions indicated the presence of merA but not merB in P. putida V1. The growth and ability of P. putida V1 to remove methylmercury in a wide range of pH (4.0 and 8.0) and temperature (10-35 °C), its tolerance to other heavy metals and ability to grow in the presence of up to 11.5 μM of methylmercury, suggest this strain as a new potential resource for degrading methylmercury contaminated sites.
Genetic Analysis of Stress Responses in Soil Bacteria for Enhanced Bioremediation of Mixed Contaminants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, Kwong-Kwok

The purpose of this project is to provide fundamental knowledge on environment stress response of subsurface bacteria and a radiation-resistant bacterium (Deinococcus radiodurans). This information will be particularly useful in the development of successful bioremediation strategies. These organisms represent two phylogenetically distinct groups of soil bacteria, each of which has specific features of interest for bioremediation. The subsurface bacteria, Sphingomonas spp (Savannah River Site), have unique degradative capabilities of organic waste. The study of subsurface bacteria will serve as a model for bioremediation using indigenous bacteria. D. radiodurans exhibits high resistance to external stress such as ionizing radiation and organicmore » solvent. The study of D. radiodurans will serve as a model for the use of genetically engineered bacteria for bioremediation.« less
Metal Accumulation and Vanadium-Induced Multidrug Resistance by Environmental Isolates of Escherichia hermannii and Enterobacter cloacae

PubMed Central

Hernández, Alicia; Mellado, Rafael P.; Martínez, José L.

1998-01-01

Contaminated soils from an oil refinery were screened for the presence of microorganisms capable of accumulating either nickel, vanadium, or both metals. Three strains of bacteria that belonged to the family Enterobacteriaceae were selected. Two of them were Escherichia hermannii strains, and outer membrane profile (OMP) analysis showed that they were similar to a strain of clinical origin; the other one was an Enterobacter cloacae strain that differed from clinical isolates. The selected bacteria accumulated both nickel and vanadium. Growth in the presence of vanadium induced multidrug resistance phenotypes in E. hermannii and E. cloacae. Incubation with this metal changed the OMP profile of E. hermannii but did not produce variations in the expression of the major OMPs of E. cloacae. PMID:9797283
Geophysical Responses of Hydrocarbon-impacted Zones at the Various Contamination Conditions

NASA Astrophysics Data System (ADS)

Kim, C.; Ko, K.; Son, J.; Kim, J.

2008-12-01

One controlled experiment and two field surveys were conducted to investigate the geoelectrical responses of hydrocarbon-contaminated zones, so called smeared zone, on the geophysical data at the hydrocarbon- contaminated sites with various conditions. One controlled physical model experiment with GPR using fresh gasoline and two different 3-D electrical resistivity investigations at the aged sites. One field site (former military facilities for arms maintenance) was mainly contaminated with lubricating oils and the other (former gas station) was contaminated with gasoline and diesel, respectively. The results from the physical model experiment show that GPR signals were enhanced when LNAPL was present as a residual saturation in the water-saturated system due to less attenuation of the electromagnetic energy through the soil medium of the hydrocarbon-impacted zone (no biodegradation), compared to when the medium was saturated with only water (no hydrocarbon impaction). In the former gas station site, 3-D resistivity results demonstrate that the highly contaminated zones were imaged with low resistivity anomalies since the biodegradation of petroleum hydrocarbons has been undergone for many years, causing the drastic increase in the TDS at the hydrocarbon-impacted zones. Finally, 3-D resistivity data obtained from the former military maintenance site show that the hydrocarbon-contaminated zones show high resistivity anomalies since the hydrocarbons such as lubricating oils at the contaminated soils were not greatly influenced by microbial degradation and has relatively well kept their original physical properties of high electrical resistivity. The results of the study illustrated that the hydrocarbon-impacted zones under various contamination conditions yielded various geophysical responses which include (1) enhanced GPR amplitudes at the fresh LNAPL (Gasoline to middle distillates) spill sites, (2) low electrical resistivity anomalies due to biodegradation at the aged LNAPL- impacted sites, and (3) high electrical resistivity anomalies at the fresh or aged sites contaminated with residual products of crude oils (lubricating oils). The study results also show that the geophysical methods, as a non-invasive sounding technique, can be effectively applied to mapping hydrocarbon-contaminated zones.
A combined PHREEQC-2/parallel fracture model for the simulation of laminar/non-laminar flow and contaminant transport with reactions

NASA Astrophysics Data System (ADS)

Masciopinto, Costantino; Volpe, Angela; Palmiotta, Domenico; Cherubini, Claudia

2010-09-01

A combination of a parallel fracture model with the PHREEQC-2 geochemical model was developed to simulate sequential flow and chemical transport with reactions in fractured media where both laminar and turbulent flows occur. The integration of non-laminar flow resistances in one model produced relevant effects on water flow velocities, thus improving model prediction capabilities on contaminant transport. The proposed conceptual model consists of 3D rock-blocks, separated by horizontal bedding plane fractures with variable apertures. Particle tracking solved the transport equations for conservative compounds and provided input for PHREEQC-2. For each cluster of contaminant pathways, PHREEQC-2 determined the concentration for mass-transfer, sorption/desorption, ion exchange, mineral dissolution/precipitation and biodegradation, under kinetically controlled reactive processes of equilibrated chemical species. Field tests have been performed for the code verification. As an example, the combined model has been applied to a contaminated fractured aquifer of southern Italy in order to simulate the phenol transport. The code correctly fitted the field available data and also predicted a possible rapid depletion of phenols as a result of an increased biodegradation rate induced by a simulated artificial injection of nitrates, upgradient to the sources.
Biofilm formation and antimicrobial sensitivity of lactobacilli contaminants from sugarcane-based fuel ethanol fermentation.

PubMed

Dellias, Marina de Toledo Ferraz; Borges, Clóvis Daniel; Lopes, Mário Lúcio; da Cruz, Sandra Helena; de Amorim, Henrique Vianna; Tsai, Siu Mui

2018-02-24

Industrial ethanol fermentation is subject to bacterial contamination that causes significant economic losses in ethanol fuel plants. Chronic contamination has been associated with biofilms that are normally more resistant to antimicrobials and cleaning efforts than planktonic cells. In this study, contaminant species of Lactobacillus isolated from biofilms (source of sessile cells) and wine (source of planktonic cells) from industrial and pilot-scale fermentations were compared regarding their ability to form biofilms and their sensitivity to different antimicrobials. Fifty lactobacilli were isolated and the most abundant species were Lactobacillus casei, Lactobacillus fermentum and Lactobacillus plantarum. The majority of the isolates (87.8%) were able to produce biofilms in pure culture. The capability to form biofilms and sensitivity to virginiamycin, monensin and beta-acids from hops, showed inter- and intra-specific variability. In the pilot-scale fermentation, Lactobacillus brevis, L. casei and the majority of L. plantarum isolates were less sensitive to beta-acids than their counterparts from wine; L. brevis isolates from biofilms were also less sensitive to monensin when compared to the wine isolates. Biofilm formation and sensitivity to beta-acids showed a positive and negative correlation for L. casei and L. plantarum, respectively.
Antibacterial Potential of an Antimicrobial Agent Inspired by Peroxidase-Catalyzed Systems

PubMed Central

Tonoyan, Lilit; Fleming, Gerard T. A.; Mc Cay, Paul H.; Friel, Ruairi; O'Flaherty, Vincent

2017-01-01

Antibiotic resistance is an increasingly serious threat to global health. Consequently, the development of non-antibiotic based therapies and disinfectants, which avoid induction of resistance, or cross-resistance, is of high priority. We report the synthesis of a biocidal complex, which is produced by the reaction between ionic oxidizable salts—iodide and thiocyanate—in the presence of hydrogen peroxide as an oxidation source. The reaction generates bactericidal reactive oxygen and iodine species. In this study, we report that the iodo-thiocyanate complex (ITC) is an effective bactericidal agent with activity against planktonic and biofilm cells of Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and methicillin-resistant S. aureus) bacteria. The minimum bactericidal concentrations and the minimum biofilm eradication concentrations of the biocidal composite were in the range of 7.8–31.3 and 31.3–250 μg ml−1, respectively. As a result, the complex was capable to cause a rapid cell death of planktonic test cultures at between 0.5 and 2 h, and complete eradication of dual and mono-species biofilms between 30 s and 10 min. Furthermore, the test bacteria, including a MRSA strain, exposed to the cocktail failed to develop resistance after serial passages. The antimicrobial activity of the ITC appears to derive from the combinational effect of the powerful species capable of oxidizing the essential biomolecules of bacteria. The use of this composition may provide an effective and efficient method for killing potential pathogens, as well as for disinfecting and removing biofilm contamination. PMID:28512449
Electrical resistivity characteristics of diesel oil-contaminated kaolin clay and a resistivity-based detection method.

PubMed

Liu, Zhibin; Liu, Songyu; Cai, Yi; Fang, Wei

2015-06-01

As the dielectric constant and conductivity of petroleum products are different from those of the pore water in soil, the electrical resistivity characteristics of oil-contaminated soil will be changed by the corresponding oil type and content. The contaminated soil specimens were manually prepared by static compaction method in the laboratory with commercial kaolin clay and diesel oil. The water content and dry density of the first group of soil specimens were controlled at 10 % and 1.58 g/cm(3). Corresponding electrical resistivities of the contaminated specimens were measured at the curing periods of 7, 14, and 28 and 90, 120, and 210 days on a modified oedometer cell with an LCR meter. Then, the electrical resistivity characteristics of diesel oil-contaminated kaolin clay were discussed. In order to realize a resistivity-based oil detection method, the other group of oil-contaminated kaolin clay specimens was also made and tested, but the initial water content, oil content, and dry density were controlled at 0~18 %, 0~18 %, 1.30~1.95 g/cm(3), respectively. Based on the test data, a resistivity-based artificial neural network (ANN) was developed. It was found that the electrical resistivity of kaolin clay decreased with the increase of oil content. Moreover, there was a good nonlinear relationship between electrical resistivity and corresponding oil content when the water content and dry density were kept constant. The decreasing velocity of the electrical resistivity of oil-contaminated kaolin clay was higher before the oil content of 12 % than after 12 %, which indicated a transition of the soil from pore water-controlled into oil-controlled electrical resistivity characteristics. Through microstructural analysis, the decrease of electrical resistivity could be explained by the increase of saturation degree together with the collapse of the electrical double layer. Environmental scanning electron microscopy (ESEM) photos indicated that the diesel oil in kaolin clay normally had three kinds of effects including oil filling, coating, and bridging. Finally, a resistivity-based ANN model was established based on the database collected from the experiment data. The performance of the model was proved to be reasonably accepted, which puts forward a possible simple, economic, and effective tool to detect the oil content in contaminated clayey soils just with four basic parameters: wet density, dry density, measured moisture content, and electrical resistivity.
Genetic Factors Involved in Fumonisin Accumulation in Maize Kernels and Their Implications in Maize Agronomic Management and Breeding

PubMed Central

Santiago, Rogelio; Cao, Ana; Butrón, Ana

2015-01-01

Contamination of maize with fumonisins depends on the environmental conditions; the maize resistance to contamination and the interaction between both factors. Although the effect of environmental factors is a determinant for establishing the risk of kernel contamination in a region, there is sufficient genetic variability among maize to develop resistance to fumonisin contamination and to breed varieties with contamination at safe levels. In addition, ascertaining which environmental factors are the most important in a region will allow the implementation of risk monitoring programs and suitable cultural practices to reduce the impact of such environmental variables. The current paper reviews all works done to address the influence of environmental variables on fumonisin accumulation, the genetics of maize resistance to fumonisin accumulation, and the search for the biochemical and/or structural mechanisms of the maize plant that could be involved in resistance to fumonisin contamination. We also explore the outcomes of breeding programs and risk monitoring of undertaken projects. PMID:26308050
Genetic Factors Involved in Fumonisin Accumulation in Maize Kernels and Their Implications in Maize Agronomic Management and Breeding.

PubMed

Santiago, Rogelio; Cao, Ana; Butrón, Ana

2015-08-20

Contamination of maize with fumonisins depends on the environmental conditions; the maize resistance to contamination and the interaction between both factors. Although the effect of environmental factors is a determinant for establishing the risk of kernel contamination in a region, there is sufficient genetic variability among maize to develop resistance to fumonisin contamination and to breed varieties with contamination at safe levels. In addition, ascertaining which environmental factors are the most important in a region will allow the implementation of risk monitoring programs and suitable cultural practices to reduce the impact of such environmental variables. The current paper reviews all works done to address the influence of environmental variables on fumonisin accumulation, the genetics of maize resistance to fumonisin accumulation, and the search for the biochemical and/or structural mechanisms of the maize plant that could be involved in resistance to fumonisin contamination. We also explore the outcomes of breeding programs and risk monitoring of undertaken projects.

Arsenite-oxidizing and arsenate-reducing bacteria associated with arsenic-rich groundwater in Taiwan

NASA Astrophysics Data System (ADS)

Liao, Vivian Hsiu-Chuan; Chu, Yu-Ju; Su, Yu-Chen; Hsiao, Sung-Yun; Wei, Chia-Cheng; Liu, Chen-Wuing; Liao, Chung-Min; Shen, Wei-Chiang; Chang, Fi-John

2011-04-01

Drinking highly arsenic-contaminated groundwater is a likely cause of blackfoot disease in Taiwan, but microorganisms that potentially control arsenic mobility in the subsurface remain unstudied. The objective of this study was to investigate the relevant arsenite-oxidizing and arsenate-reducing microbial community that exists in highly arsenic-contaminated groundwater in Taiwan. We cultured and identified arsenic-transforming bacteria, analyzed arsenic resistance and transformation, and determined the presence of genetic markers for arsenic transformation. In total, 11 arsenic-transforming bacterial strains with different colony morphologies and varying arsenic transformation abilities were isolated, including 10 facultative anaerobic arsenate-reducing bacteria and one strictly aerobic arsenite-oxidizing bacterium. All of the isolates exhibited high levels of arsenic resistance with minimum inhibitory concentrations of arsenic ranging from 2 to 200 mM. Strain AR-11 was able to rapidly oxidize arsenite to arsenate at concentrations relevant to environmental groundwater samples without the addition of any electron donors or acceptors. We provide evidence that arsenic-reduction activity may be conferred by the ars operon(s) that were not amplified by the designed primers currently in use. The 16S rRNA sequence analysis grouped the isolates into the following genera: Pseudomonas, Bacillus, Psychrobacter, Vibrio, Citrobacter, Enterobacter, and Bosea. Among these genera, we present the first report of the genus Psychrobacter being involved in arsenic reduction. Our results further support the hypothesis that bacteria capable of either oxidizing arsenite or reducing arsenate coexist and are ubiquitous in arsenic-contaminated groundwater.
Incorporating a Capability for Estimating Inhalation Doses in ...

EPA Pesticide Factsheets

Report and Data Files This report presents the approach to be used to incorporate in the U.S. Environmental Protection Agency’s TEVA-SPOT software (U.S.EPA 2014) a capability for estimating inhalation doses that result from the most important sources of contaminated aerosols and volatile contaminants during a contamination event.
Multiple antibiotic resistance patterns of rhizospheric bacteria isolated from Phragmites australis growing in constructed wetland for distillery effluent treatment.

PubMed

Chaturvedi, Sonal; Chandra, Ram; Rai, Vibhuti

2008-01-01

Susceptibility patterns of 12 different antibiotics were investigated against rhizospheric bacteria isolated from Phragmites australis from three different zones i.e. upper (0-5 cm), middle (5-10 cm), lower (10-15 cm) in constructed wetland system with and without distillery effluent. The major pollutants of distillery effluent were phenols, sulphide, heavy metals, and higher levels of biological oxygen demand (BOD), chemical oxygen demand (COD) etc. The antibiotic resistance properties of bacteria were correlated with the heavy metal tolerance (one of distillery pollutant). Twenty-two species from contaminated and seventeen species from non-contaminated site were tested by agar disc-diffusion method. The results revealed that more than 63% of total isolates were resistance towards one or more antibiotics tested from all the three different zones of contaminated sites. The multiple-drug resistance property was shown by total 8 isolates from effluent contaminated region out of which 3 isolates were from upper zone, 3 isolates from middle zone and 2 isolates were from lower zone. Results indicated that isolates from contaminated rhizosphere were found more resistant to antibiotics than isolates from non-contaminated rhizosphere. Further this study produces evidence suggesting that tolerance to antibiotics was acquired by isolates for the adaptation and detoxification of all the pollutants present in the effluent at contaminated site. This consequently facilitated the phytoremediation of effluent, which emerges the tolerance and increases resistance to antibiotics.
PARAMETERS OF TREATED STAINLESS STEEL SURFACES IMPORTANT FOR RESISTANCE TO BACTERIAL CONTAMINATION

EPA Science Inventory

Use of materials that are resistant to bacterial contamination could enhance food safety during processing. Common finishing treatments of stainless steel surfaces used for components of poultry processing equipment were tested for resistance to bacterial attachment. Surface char...
QTL mapping and candidate genes for resistance to Fusarium ear rot and fumonisin contamination in maize.

PubMed

Maschietto, Valentina; Colombi, Cinzia; Pirona, Raul; Pea, Giorgio; Strozzi, Francesco; Marocco, Adriano; Rossini, Laura; Lanubile, Alessandra

2017-01-21

Fusarium verticillioides is a common maize pathogen causing ear rot (FER) and contamination of the grains with the fumonisin B1 (FB1) mycotoxin. Resistance to FER and FB1 contamination are quantitative traits, affected by environmental conditions, and completely resistant maize genotypes to the pathogen are so far unknown. In order to uncover genomic regions associated to reduced FER and FB1 contamination and identify molecular markers for assisted selection, an F 2:3 population of 188 progenies was developed crossing CO441 (resistant) and CO354 (susceptible) genotypes. FER severity and FB1 contamination content were evaluated over 2 years and sowing dates (early and late) in ears artificially inoculated with F. verticillioides by the use of either side-needle or toothpick inoculation techniques. Weather conditions significantly changed in the two phenotyping seasons and FER and FB1 content distribution significantly differed in the F 3 progenies according to the year and the sowing time. Significant positive correlations (P < 0.01) were detected between FER and FB1 contamination, ranging from 0.72 to 0.81. A low positive correlation was determined between FB1 contamination and silking time (DTS). A genetic map was generated for the cross, based on 41 microsatellite markers and 342 single nucleotide polymorphisms (SNPs) derived from Genotyping-by-Sequencing (GBS). QTL analyses revealed 15 QTLs for FER, 17 QTLs for FB1 contamination and nine QTLs for DTS. Eight QTLs located on linkage group (LG) 1, 2, 3, 6, 7 and 9 were in common between FER and FB1, making possible the selection of genotypes with both low disease severity and low fumonisin contamination. Moreover, five QTLs on LGs 1, 2, 4, 5 and 9 located close to previously reported QTLs for resistance to other mycotoxigenic fungi. Finally, 24 candidate genes for resistance to F. verticillioides are proposed combining previous transcriptomic data with QTL mapping. This study identified a set of QTLs and candidate genes that could accelerate breeding for resistance of maize lines showing reduced disease severity and low mycotoxin contamination determined by F. verticillioides.
Evaluation of maize inbred lines for resistance to pre-harvest aflatoxin and fumonisin contamination in the field

USDA-ARS?s Scientific Manuscript database

Two important mycotoxins, aflatoxin and fumonisin, are among the most potent naturally occurring carcinogens, contaminating maize (Zea mays L.) and affecting the crop yield and quality. Resistance of maize to pre-harvest mycotoxin contamination, specifically aflatoxin produced by Aspergillus flavus ...
Hot rocket plume experiment - Survey and conceptual design. [of rhenium-iridium bipropellants

NASA Technical Reports Server (NTRS)

Millard, Jerry M.; Luan, Taylor W.; Dowdy, Mack W.

1992-01-01

Attention is given to a space-borne engine plume experiment study to fly an experiment which will both verify and quantify the reduced contamination from advanced rhenium-iridium earth-storable bipropellant rockets (hot rockets) and provide a correlation between high-fidelity, in-space measurements and theoretical plume and surface contamination models. The experiment conceptual design is based on survey results from plume and contamination technologists throughout the U.S. With respect to shuttle use, cursory investigations validate Hitchhiker availability and adaptability, adequate remote manipulator system (RMS) articulation and dynamic capability, acceptable RMS attachment capability, adequate power and telemetry capability, and adequate flight altitude and attitude/orbital capability.
Geoelectrical mapping and groundwater contamination

NASA Astrophysics Data System (ADS)

Blum, Rainer

Specific electrical resistivity of near-surface materials is mainly controlled by the groundwater content and thus reacts extremely sensitive to any change in the ion content. Geoelectric mapping is a well-established, simple, and inexpensive technique for observing areal distributions of apparent specific electrical resistivities. These are a composite result of the true resistivities in the underground, and with some additional information the mapping of apparent resistivities can help to delineate low-resistivity groundwater contaminations, typically observed downstream from sanitary landfills and other waste sites. The presence of other good conductors close to the surface, mainly clays, is a serious noise source and has to be sorted out by supporting observations of conductivities in wells and geoelectric depth soundings. The method may be used to monitor the extent of groundwater contamination at a specific time as well as the change of a contamination plume with time, by carrying out repeated measurements. Examples for both are presented.
Contamination and UV lasers: lessons learned

NASA Astrophysics Data System (ADS)

Daly, John G.

2015-09-01

Laser induced damage to optical elements has been a subject of significant research, development, and improvement, since the first lasers were built over the last 50 years. Better materials, with less absorption, impurities, and defects are available, as well as surface coatings with higher laser damage resistance. However, the presence of contamination (particles, surface deposition films, or airborne) can reduce the threshold for damage by several orders of magnitude. A brief review of the anticipated laser energy levels for damage free operation is presented as a lead into the problems associated with contamination for ultraviolet (UV) laser systems. As UV lasers become more common in applications especially in areas such as lithography, these problems have limited reliability and added to costs. This has been characterized as Airborne Molecular Contamination (AMC) in many published reports. Normal engineering guidelines such as screening materials within the optical compartment for low outgassing levels is the first step. The use of the NASA outgassing database (or similar test methods) with low Total Mass Loss (TML) and Condensed Collected Volatiles Collected Mass (CVCM) is a good baseline. Energetic UV photons are capable of chemical bond scission and interaction with surface contaminant or airborne materials results in deposition of obscuring film laser footprints that continue to degrade laser system performance. Laser systems with average powers less than 5 mW have been shown to exhibit aggressive degradation. Lessons learned over the past 15 years with UV laser contamination and steps to reduce risk will be presented.
Impact of Some Ecological Factors on Fecal Contamination of Drinking Water by Diarrheagenic Antibiotic-Resistant Escherichia coli in Zagazig City, Egypt

PubMed Central

Gohar, Maha Kamal; Atta, Amal Hassan

2016-01-01

Fecal contamination of drinking water is a major health problem which accounts for many cases of diarrhea mainly in infants and foreigners. This contamination is a complex interaction of many parameters. Antibiotic resistance among bacterial isolates complicates the problem. The study was done to identify fecal contamination of drinking water by Diarrheagenic Antibiotic-Resistant Escherichia coli in Zagazig city and to trace reasons for such contamination, three hundred potable water samples were investigated for E. coli existence. Locations of E. coli positive samples were investigated in relation to population density, water source, and type of water pipe. Sixteen E. coli strains were isolated. Antibiotic sensitivity was done and enterotoxigenic, enteropathogenic, and enterohaemorrhagic virulence genes were investigated by PCR. Probability of fecal contamination correlated with higher population density, with increased distance from Zagazig water plant, and with asbestos cement water pipes. Resistance to at least one antimicrobial drug was found in all isolates. Virulence genes were detected in a rate of 26.27%, 13.13%, 20%, 6.67%, and 33.33% for LT, ST, stx1, stx2, and eae genes, respectively. This relatively high frequency of fecal contamination points towards the high risk of developing diarrhea by antibiotic resistant DEC in low socioeconomic communities particularly with old fashion distribution systems. PMID:27725834
Arsenic-resistant and plant growth-promoting Firmicutes and γ-Proteobacteria species from industrially polluted irrigation water and corresponding cropland.

PubMed

Qamar, N; Rehman, Y; Hasnain, S

2017-09-01

The aim of the study was to explore irrigation water polluted with industrial waste and corresponding cropland to screen bacteria for As detoxification and plant growth promotion. Plant growth-promoting (PGP) As-resistant cropland bacteria were isolated from contaminated irrigation water and corresponding agricultural soil. Phylogenetic analysis revealed that the isolates belonged to two distinct bacterial lineages; Firmicutes and γ-Proteobacteria. Maximum As(V) resistance was exhibited by Klebsiella pneumoniae T22 and Klebsiella oxytoca N53 (550 mmol l -1 ), whereas maximum resistance against As(III) was exhibited by K. oxytoca N53 (200 mmol l -1 ). Maximum As(V) reduction was shown by K. pneumoniae T22 (6·7 mmol l -1 ), whereas maximum As(III) oxidation was exhibited by Bacillus subtilis T23 (4·8 mmol l -1 ). As resistance genes arsB and ACR3 were detected in many of the isolates through polymerase chain reaction. Many of these isolates exhibited PGP traits such as hydrogen cyanide and auxin production as well as phosphate solubilization. The bacterial strains were able to enhance Triticum aestivum growth both in the absence and presence of As, and statistically significant increase in shoot and root lengths was observed especially in case of Acinetobacter lwoffii T24 and Citrobacter freundii N52-treated plants. Cropland bacteria have the ability to support plant growth. Bacteria of croplands irrigated with industrially polluted water develop resistance against toxicants. These bacteria are helpful for the plant growth in such contaminated lands. The bacteria capable of both As detoxification and plant growth promotion, such as A. lwoffii T24 and C. freundii N52, are ideal for remediation and reclamation of polluted lands for agriculture purposes. © 2017 The Society for Applied Microbiology.
Determination of water saturation using gas phase partitioning tracers and time-lapse electrical conductivity measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Timothy C.; Oostrom, Martinus; Truex, Michael J.

2013-05-21

Water saturation is an important indicator of contaminant distribution and plays a governing role in contaminant transport within the vadose zone. Understanding the water saturation distribution is critical for both remediation and contaminant flux monitoring in unsaturated environments. In this work we propose and demonstrate a method of remotely determining water saturation levels using gas phase partitioning tracers and time-lapse bulk electrical conductivity measurements. The theoretical development includes the partitioning chemistry for the tracers we demonstrate (ammonia and carbon dioxide), as well as a review of the petrophysical relationship governing how these tracers influence bulk conductivity. We also investigate methodsmore » of utilizing secondary information provided by electrical conductivity breakthrough magnitudes induced by the tracers. We test the method on clean, well characterized, intermediate-scale sand columns under controlled conditions. Results demonstrate the capability to predict partitioning coefficients and accurately monitor gas breakthrough curves along the length of the column according to the corresponding electrical conductivity response, leading to accurate water saturation estimates. This work is motivated by the need to develop effective characterization and monitoring techniques for contaminated deep vadose zone environments, and provides a proof-of-concept toward uniquely characterizing and monitoring water saturation levels at the field scale and in three-dimensions using electrical resistivity tomography.« less
Relationships between PEMFC Cathode Kinetic Losses and Contaminants’ Dipole Moment and Adsorption Energy on Pt

DOE PAGES

St-Pierre, Jean; Zhai, Yunfeng; Ge, Junjie

2016-01-05

A database summarizing the effects of 21 contaminants on the performance of proton exchange membrane fuel cells (PEMFCs) was used to examine relationships between cathode kinetic losses and contaminant physicochemical parameters. Impedance spectroscopy data were employed to obtain oxygen reduction kinetic resistances by fitting data in the 10-158 Hz range to a simplified equivalent circuit. The contaminant dipole moment and the adsorption energy of the contaminant on a Pt surface were chosen as parameters. Dipole moments did not correlate with dimensionless cathode kinetic resistances. In contrast, adsorption energies were quantitatively and linearly correlated with minimum dimensionless cathode kinetic resistances. Contaminantsmore » influence the oxygen reduction for contaminant adsorption energies smaller than -24.5 kJ mol -1, a value near the high limit of the adsorption energy of O 2 on Pt. Dimensionless cathode kinetic resistances linearly increase with decreasing O 2 adsorption energies below -24.5 kJ mol -1. Measured total cell voltage losses are mostly larger than the cathode kinetic losses calculated from kinetic resistance changes, which indicates the existence of other sources of performance degradation. Modifications to the experimental procedure are proposed to ensure that data are comparable on a similar basis and improve the correlation between contaminant adsorption energy and kinetic cell voltage losses.« less
Relationships between PEMFC Cathode Kinetic Losses and Contaminants’ Dipole Moment and Adsorption Energy on Pt

DOE Office of Scientific and Technical Information (OSTI.GOV)

St-Pierre, Jean; Zhai, Yunfeng; Ge, Junjie

A database summarizing the effects of 21 contaminants on the performance of proton exchange membrane fuel cells (PEMFCs) was used to examine relationships between cathode kinetic losses and contaminant physicochemical parameters. Impedance spectroscopy data were employed to obtain oxygen reduction kinetic resistances by fitting data in the 10-158 Hz range to a simplified equivalent circuit. The contaminant dipole moment and the adsorption energy of the contaminant on a Pt surface were chosen as parameters. Dipole moments did not correlate with dimensionless cathode kinetic resistances. In contrast, adsorption energies were quantitatively and linearly correlated with minimum dimensionless cathode kinetic resistances. Contaminantsmore » influence the oxygen reduction for contaminant adsorption energies smaller than -24.5 kJ mol -1, a value near the high limit of the adsorption energy of O 2 on Pt. Dimensionless cathode kinetic resistances linearly increase with decreasing O 2 adsorption energies below -24.5 kJ mol -1. Measured total cell voltage losses are mostly larger than the cathode kinetic losses calculated from kinetic resistance changes, which indicates the existence of other sources of performance degradation. Modifications to the experimental procedure are proposed to ensure that data are comparable on a similar basis and improve the correlation between contaminant adsorption energy and kinetic cell voltage losses.« less
Extreme Ionizing-Radiation-Resistant Bacterium

NASA Technical Reports Server (NTRS)

Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

2012-01-01

There is a growing concern that desiccation and extreme radiation-resistant, non-spore-forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequent proliferation on another solar body. Such forward contamination would jeopardize future life detection or sample return technologies. The prime focus of NASA s planetary protection efforts is the development of strategies for inactivating resistance-bearing microorganisms. Eradification techniques can be designed to target resistance-conferring microbial populations by first identifying and understanding their physiologic and biochemical capabilities that confers its elevated tolerance (as is being studied in Deinococcus phoenicis, as a result of this description). Furthermore, hospitals, food, and government agencies frequently use biological indicators to ensure the efficacy of a wide range of radiation- based sterilization processes. Due to their resistance to a variety of perturbations, the non-spore forming D. phoenicis may be a more appropriate biological indicator than those currently in use. The high flux of cosmic rays during space travel and onto the unshielded surface of Mars poses a significant hazard to the survival of microbial life. Thus, radiation-resistant microorganisms are of particular concern that can survive extreme radiation, desiccation, and low temperatures experienced during space travel. Spore-forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate these extreme conditions. Since the Viking era, spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. Members of the non-spore-forming bacterial community such as Deinococcus radiodurans can survive acute exposures to ionizing radiation (5 kGy), ultraviolet light (1 kJ/sq m), and desiccation (years). These resistive phenotypes of Deinococcus enhance the potential for transfer, and subsequent proliferation, on another solar body such as Mars and Europa. These organisms are more likely to escape planetary protection assays, which only take into account presence of spores. Hence, presences of extreme radiation-resistant Deinococcus in the cleanroom facility where spacecraft are assembled pose a serious risk for integrity of life-detection missions. The microorganism described herein was isolated from the surfaces of the cleanroom facility in which the Phoenix Lander was assembled. The isolated bacterial strain was subjected to a comprehensive polyphasic analysis to characterize its taxonomic position. This bacterium exhibits very low 16SrRNA similarity with any other environmental isolate reported to date. Both phenotypic and phylogenetic analyses clearly indicate that this isolate belongs to the genus Deinococcus and represents a novel species. The name Deinococcus phoenicis was proposed after the Phoenix spacecraft, which was undergoing assembly, testing, and launch operations in the spacecraft assembly facility at the time of isolation. D. phoenicis cells exhibited higher resistance to ionizing radiation (cobalt-60; 14 kGy) than the cells of the D. radiodurans (5 kGy). Thus, it is in the best interest of NASA to thoroughly characterize this organism, which will further assess in determining the potential for forward contamination. Upon the completion of genetic and physiological characteristics of D. phoenicis, it will be added to a planetary protection database to be able to further model and predict the probability of forward contamination.
Extreme Ionizing-Radiation-Resistant Bacterium

NASA Technical Reports Server (NTRS)

Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

2013-01-01

There is a growing concern that desiccation and extreme radiation-resistant, non-spore-forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequent proliferation on another solar body. Such forward contamination would jeopardize future life detection or sample return technologies. The prime focus of NASA s planetary protection efforts is the development of strategies for inactivating resistance-bearing micro-organisms. Eradi cation techniques can be designed to target resistance-conferring microbial populations by first identifying and understanding their physiologic and biochemical capabilities that confers its elevated tolerance (as is being studied in Deinococcus phoenicis, as a result of this description). Furthermore, hospitals, food, and government agencies frequently use biological indicators to ensure the efficacy of a wide range of radiation-based sterilization processes. Due to their resistance to a variety of perturbations, the nonspore forming D. phoenicis may be a more appropriate biological indicator than those currently in use. The high flux of cosmic rays during space travel and onto the unshielded surface of Mars poses a significant hazard to the survival of microbial life. Thus, radiation-resistant microorganisms are of particular concern that can survive extreme radiation, desiccation, and low temperatures experienced during space travel. Spore-forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate these extreme conditions. Since the Viking era, spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. Members of the non-sporeforming bacterial community such as Deinococcus radiodurans can survive acute exposures to ionizing radiation (5 kGy), ultraviolet light (1 kJ/m2), and desiccation (years). These resistive phenotypes of Deinococcus enhance the potential for transfer, and subsequent proliferation, on another solar body such as Mars and Europa. These organisms are more likely to escape planetary protection assays, which only take into account presence of spores. Hence, presences of extreme radiation-resistant Deinococcus in the cleanroom facility where spacecraft are assembled pose a serious risk for integrity of life-detection missions. The microorganism described herein was isolated from the surfaces of the cleanroom facility in which the Phoenix Lander was assembled. The isolated bacterial strain was subjected to a comprehensive polyphasic analysis to characterize its taxonomic position. This bacterium exhibits very low 16SrRNA similarity with any other environmental isolate reported to date. Both phenotypic and phylogenetic analyses clearly indicate that this isolate belongs to the genus Deinococcus and represents a novel species. The name Deinococcus phoenicis was proposed after the Phoenix spacecraft, which was undergoing assembly, testing, and launch operations in the spacecraft assembly facility at the time of isolation. D. phoenicis cells exhibited higher resistance to ionizing radiation (cobalt-60; 14 kGy) than the cells of the D. radiodurans (5 kGy). Thus, it is in the best interest of NASA to thoroughly characterize this organism, which will further assess in determining the potential for forward contamination. Upon the completion of genetic and physiological characteristics of D. phoenicis, it will be added to a planetary protection database to be able to further model and predict the probability of forward contamination.
Nitrification and Autotrophic Nitrifying Bacteria in a Hydrocarbon-Polluted Soil

PubMed Central

Deni, Jamal; Penninckx, Michel J.

1999-01-01

In vitro ammonia-oxidizing bacteria are capable of oxidizing hydrocarbons incompletely. This transformation is accompanied by competitive inhibition of ammonia monooxygenase, the first key enzyme in nitrification. The effect of hydrocarbon pollution on soil nitrification was examined in situ. In a microcosm study, adding diesel fuel hydrocarbon to an uncontaminated soil (agricultural unfertilized soil) treated with ammonium sulfate dramatically reduced the amount of KCl-extractable nitrate but stimulated ammonium consumption. In a soil with long history of pollution that was treated with ammonium sulfate, 90% of the ammonium was transformed into nitrate after 3 weeks of incubation. Nitrate production was twofold higher in the contaminated soil than in the agricultural soil to which hydrocarbon was not added. To assess if ammonia-oxidizing bacteria acquired resistance to inhibition by hydrocarbon, the contaminated soil was reexposed to diesel fuel. Ammonium consumption was not affected, but nitrate production was 30% lower than nitrate production in the absence of hydrocarbon. The apparent reduction in nitrification resulted from immobilization of ammonium by hydrocarbon-stimulated microbial activity. These results indicated that the hydrocarbon inhibited nitrification in the noncontaminated soil (agricultural soil) and that ammonia-oxidizing bacteria in the polluted soil acquired resistance to inhibition by the hydrocarbon, possibly by increasing the affinity of nitrifying bacteria for ammonium in the soil. PMID:10473409
High Quality Bioreplication of Intricate Nanostructures from a Fragile Gecko Skin Surface with Bactericidal Properties

NASA Astrophysics Data System (ADS)

Green, David William; Lee, Kenneth Ka-Ho; Watson, Jolanta Anna; Kim, Hyun-Yi; Yoon, Kyung-Sik; Kim, Eun-Jung; Lee, Jong-Min; Watson, Gregory Shaun; Jung, Han-Sung

2017-01-01

The external epithelial surfaces of plants and animals are frequently carpeted with small micro- and nanostructures, which broadens their adaptive capabilities in challenging physical habitats. Hairs and other shaped protuberances manage with excessive water, light contaminants, predators or parasites in innovative ways. We are interested in transferring these intricate architectures onto biomedical devices and daily-life surfaces. Such a project requires a very rapid and accurate small-scale fabrication process not involving lithography. In this study, we describe a simple benchtop biotemplating method using shed gecko lizard skin that generates duplicates that closely replicate the small nanotipped hairs (spinules) that cover the original skin. Synthetic replication of the spinule arrays in popular biomaterials closely matched the natural spinules in length. More significantly, the shape, curvature and nanotips of the synthetic arrays are virtually identical to the natural ones. Despite some small differences, the synthetic gecko skin surface resisted wetting and bacterial contamination at the same level as natural shed skin templates. Such synthetic gecko skin surfaces are excellent platforms to test for bacterial control in clinical settings. We envision testing the biocidal properties of the well-matched templates for fungal spores and viral resistance in biomedicine as well as co/multi-cultures.
Identification of genomic region controlling resistance to aflatoxin contamination in a peanut recombinant inbred line population (Tifrunner x GT-C20)

USDA-ARS?s Scientific Manuscript database

Aflatoxin contamination of peanut is a significant threat to global food safety. In this study we performed quantitative trait loci (QTL) analysis to identify peanut genomic regions contributing to aflatoxin contamination resistance in a recombinant inbred line (RIL) population derived from the Tifr...
Flexible foils formed by a prolonged electron beam irradiation in scanning electron microscope

NASA Astrophysics Data System (ADS)

Čechal, Jan; Šikola, Tomáš

2017-11-01

The ubiquitous presence of hydrocarbon contamination on solid surfaces alters their inherent physical properties and complicates the surface analyses. An irradiation of sample surface with electron beam can lead to the chemical transformation of the hydrocarbon layer to carbon films, which are flexible and capable of acting as a barrier for chemical etching of an underlying material. The growth of these foils is limited by supply of hydrocarbons to the writing beam position rather than the electron dose or electron beam current. The prepared films can find their applications in fabrication of surface nanostructures without a need of an electron sensitive resist material.

Geoelectrical mapping of the Soil and Groundwater Contaminated Site: Case Study from Taiwan

NASA Astrophysics Data System (ADS)

Liu, H. C.; Lin, C. P.; Wang, T. P.

2016-12-01

In recent years, geophysical technology has been widely used in soil and groundwater investigation and remediation of contaminated sites assessments in Taiwan, such technology can securely work in either small or large sampler areas, and collect data from the traditional one-dimensional data to two-dimensional and three-dimensional data. In other words, geophysical technology helps provide more information to assist the data interpretation, and improves the overall effectiveness of soil and groundwater contamination surveys. Electrical Resistivity Tomography (ERT) is one of useful geophysical technology to the soil and groundwater contaminated sites. By estimating the groundwater flow direction and distribution of contaminations, we could establish monitoring or sampling wells in potential pollution areas. ERT survey could delineate the contaminated areas with high concentrations in relatively simple sites. Even in the seriously DNAPL leakage cases, it is possible to directly detect the DNAPL pool. In this study, we presented the investigation outcomes of electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) at the DNAPLs-impacted site. Evaluation of ERT/GPR technique deployment in detecting buried DNAPLs and assessment of remediation efforts are also discussed. Results indicated zones with anomalously high resistivity to be associated with contaminated DNAPLs presence. Resistivity maps clearly outlined the subsurface distribution and the possible migration path of DNAPLs.
Biotechnological advances for combating Aspergillus flavus and aflatoxin contamination in crops.

PubMed

Bhatnagar-Mathur, Pooja; Sunkara, Sowmini; Bhatnagar-Panwar, Madhurima; Waliyar, Farid; Sharma, Kiran Kumar

2015-05-01

Aflatoxins are toxic, carcinogenic, mutagenic, teratogenic and immunosuppressive byproducts of Aspergillus spp. that contaminate a wide range of crops such as maize, peanut, and cotton. Aflatoxin not only affects crop production but renders the produce unfit for consumption and harmful to human and livestock health, with stringent threshold limits of acceptability. In many crops, breeding for resistance is not a reliable option because of the limited availability of genotypes with durable resistance to Aspergillus. Understanding the fungal/crop/environment interactions involved in aflatoxin contamination is therefore essential in designing measures for its prevention and control. For a sustainable solution to aflatoxin contamination, research must be focused on identifying and improving knowledge of host-plant resistance factors to aflatoxin accumulation. Current advances in genetic transformation, proteomics, RNAi technology, and marker-assisted selection offer great potential in minimizing pre-harvest aflatoxin contamination in cultivated crop species. Moreover, developing effective phenotyping strategies for transgenic as well as precision breeding of resistance genes into commercial varieties is critical. While appropriate storage practices can generally minimize post-harvest aflatoxin contamination in crops, the use of biotechnology to interrupt the probability of pre-harvest infection and contamination has the potential to provide sustainable solution. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
High-resolution analyses reveal structural diversity patterns of microbial communities in Chromite Ore Processing Residue (COPR) contaminated soils.

PubMed

Min, Xiaobo; Wang, Yangyang; Chai, Liyuan; Yang, Zhihui; Liao, Qi

2017-09-01

To explore how heavy metal contamination in Chromite Ore Processing Residue (COPR) disposal sites determine the dissimilarities of indigenous microbial communities, 16S rRNA gene MiSeq sequencing and advanced statistical methods were applied. 13 soil samples were collected from three COPR disposal sites in Mouding of southwestern, Shangnan of northwestern and Yima of central China. The results of analyses of variance (ANOVA), similarities (ANOSIM), and non-metric multidimensional scaling (NMDS) showed that the structural diversity of the microbial communities in the samples with high total chromium (Cr) content (more than 300 mg kg -1 ; High group) were significantly lesser than in the Low group (less than 90 mg kg -1 ) regardless of their geographical distribution. But their diversity had virtually rehabilitated under the pressures of long-term metal contamination. Furthermore, the similarity percentage (SIMPER) analysis indicated that the major dissimilarity contributors Micrococcaceae, Delftia, and Streptophyta, possibly having Cr(VI)-resistant and/or Cr(VI)-reducing capability, were dominant in the High group, while Ramlibacter and Gemmatimonas with potential resistances to other heavy metals were prevalent in the Low group. In addition, the multivariate regression tree (MRT), aggregated boosted tree (ABT), and Mantel test revealed that total Cr content affiliated with Cr(VI) was the principal factor shaping the dissimilarities between the soil microbial communities in the COPR sites. Our findings provide a deep insight of the influence of these heavy metals on the microbial communities in the COPR disposal sites and will facilitate bioremediation on such site. Copyright © 2017 Elsevier Ltd. All rights reserved.
Recent status of resist outgas testing for metal containing resists at EIDEC

NASA Astrophysics Data System (ADS)

Shiobara, Eishi; Mikami, Shinji; Yamada, Kenji

2018-03-01

The metal containing resist is one of the strong candidates for high lithographic performance Extreme Ultraviolet (EUV) resists. EIDEC has prepared the infrastructure for outgas testing in hydrogen environment for metal containing resists at High Power EUV irradiation tool (HPEUV). We have experimentally obtained the preliminary results of the non-cleanable metal contamination on witness sample using model material by HPEUV [1]. The metal contamination was observed at only the condition of hydrogen environment. It suggested the generation of volatile metal hydrides by hydrogen radicals. Additionally, the metal contamination on a witness sample covered with Ru was not removed by hydrogen radical cleaning. The strong interaction between the metal hydride and Ru was confirmed by the absorption simulation [2]. Recently, ASML announced a resist outgassing barrier technology using Dynamic Gas Lock (DGL) membrane located between projection optics and wafer stage [3, 4]. DGL membrane blocks the diffusion of all kinds of resist outgassing to the projection optics and prevents the reflectivity loss of EUV mirrors. The investigation of DGL membrane for high volume manufacturing is just going on. It extends the limitation of material design for EUV resists. However, the DGL membrane has an impact for the productivity of EUV scanners due to the transmission loss of EUV light and the necessity of periodic maintenance. The well understanding and control of the outgassing characteristics of metal containing resists may help to improve the productivity of EUV scanner. We consider the outgas evaluation for the resists still useful. For the improvement of resist outgas testing in hydrogen, there are some issues such as the contamination limited regime, the optimization of exposure dose to obtain the measurable contamination film thickness and the detection of minimum amount of metal related outgas species generated. We are considering a new platform of outgas testing for metal containing resists based on the electron-beam irradiation system as one of the solutions for these issues. The concept is presented in this paper.
Robustness and Radiation Resistance of the Pale Grass Blue Butterfly from Radioactively Contaminated Areas: A Possible Case of Adaptive Evolution.

PubMed

Nohara, Chiyo; Hiyama, Atsuki; Taira, Wataru; Otaki, Joji M

2018-02-14

The pale grass blue butterfly, Zizeeria maha, has been used to evaluate biological impacts of the Fukushima nuclear accident in March 2011. Here, we examined the possibility that butterflies have adapted to be robust in the contaminated environment. Larvae (n = 2432) were obtained from adult butterflies (n = 20) collected from 7 localities with various contamination levels in May 2012, corresponding to the 7th generation after the accident. When the larvae were reared on non-contaminated host plant leaves from Okinawa, the normality rates of natural exposure without artificial irradiation (as an indication of robustness) were high not only in the least contaminated locality but also in the most contaminated localities. The normality rates were similarly obtained when the larvae were reared on non-contaminated leaves with external irradiation or on contaminated leaves from Fukushima to deliver internal irradiation. The normality rate of natural exposure and that of external or internal exposure were correlated, suggesting that radiation resistance (or susceptibility) likely reflects general state of health. The normality rate of external or internal exposure was divided by the relative normality rate of natural exposure, being defined as the resistance value. The resistance value was the highest in the populations of heavily contaminated localities and was inversely correlated with the distance from the Fukushima Dai-ichi nuclear power plant. These results suggest that the butterfly population might have adapted to the contaminated environment within approximately 1 year after the accident. The present study may partly explain the decrease in mortality and abnormality rates later observed in the contaminated areas. © The American Genetic Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
DOWN-STREAM SPATIAL DISTRIBUTION OF ANTIBIOTIC RESISTANCE TRAITS ALONG METAL CONTAMINATED STREAM REACHES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tuckfield, C; J V Mcarthur

2007-04-16

Sediment bacteria samples were collected from three streams in South Carolina, two contaminated with multiple metals (Four Mile Creek and Castor Creek), one uncontaminated (Meyers Branch), and another metal contaminated stream (Lampert Creek) in northern Washington State. Growth plates inoculated with Four Mile Creek sample extracts show bacteria colony growth after incubation on plates containing either one of two aminoglycosides (kanamycin or streptomycin), tetracycline or chloramphenocol. This study analyzes the spatial pattern of antibiotic resistance in culturable sediment bacteria in all four streams that may be due to metal contamination. We summarize the two aminoglycoside resistance measures and the 10more » metals concentrations by Principal Components Analysis. Respectively, 63% and 58% of the variability was explained in the 1st principal component of each variable set. We used the respective multivariate summary metrics (i.e. 1st principal component scores) as input measures for exploring the spatial correlation between antibiotic resistance and metal concentration for each stream reach sampled. Results show a significant and negative correlation between metals scores versus aminoglycoside resistance scores and suggest that selection for metal tolerance among sediment bacteria may influence selection for antibiotic resistance differently than previously supposed.. In addition, we borrow a method from geostatistics (variography) wherein a spatial cross-correlation analysis shows that decreasing metal concentrations scores are associated with increasing aminoglycoside resistance scores as the separation distance between sediment samples decreases, but for contaminated streams only. Since these results were counter to our initial expectation and to other experimental evidence for water column bacteria, we suspect our field results are influenced by metal bioavailability in the sediments and by a contaminant promoted interaction or ''cocktail effect'' from complex combinations of pollution mediated selection agents.« less
Copper Contamination Impairs Herbivore Initiation of Seaweed Inducible Defenses and Decreases Their Effectiveness

PubMed Central

2015-01-01

Seaweed-herbivore interactions are often mediated by environmental conditions, yet the roles of emerging anthropogenic stressors on these interactions are poorly understood. For example, chemical contaminants have unknown consequences on seaweed inducible resistance and herbivore response to these defenses despite known deleterious effects of contaminants on animal inducible defenses. Here, we investigated the effect of copper contamination on the interactions between a snail herbivore and a brown seaweed that displays inducible resistance to grazing. We examined seaweed inducible resistance and its effectiveness for organisms exposed to copper at two time points, either during induction or after herbivores had already induced seaweed defenses. Under ambient conditions, non-grazed tissues were more palatable than grazed tissues. However, copper additions negated the preference for non-grazed tissues regardless of the timing of copper exposure, suggesting that copper decreased both how herbivores initiated these inducible defenses and their subsequent effectiveness. Copper decreased stimulation of defenses, at least in part, by suppressing snail grazing pressure—the cue that turns inducible defenses on. Copper decreased effectiveness of defenses by preventing snails from preferentially consuming non-grazed seaweed. Thus, contaminants can potentially stress communities by changing seaweed-herbivore interactions mediated via inducible defenses. Given the ubiquity of seaweed inducible resistance and their potential influence on herbivores, we hypothesize that copper contamination may change the impact of these resistant traits on herbivores. PMID:26274491
Mobile genetic elements and antibiotic resistance in mine soil amended with organic wastes.

PubMed

Garbisu, Carlos; Garaiyurrebaso, Olatz; Lanzén, Anders; Álvarez-Rodríguez, Itxaso; Arana, Lide; Blanco, Fernando; Smalla, Kornelia; Grohmann, Elisabeth; Alkorta, Itziar

2018-04-15

Metal resistance has been associated with antibiotic resistance due to co- or cross-resistance mechanisms. Here, metal contaminated mine soil treated with organic wastes was screened for the presence of mobile genetic elements (MGEs). The occurrence of conjugative IncP-1 and mobilizable IncQ plasmids, as well as of class 1 integrons, was confirmed by PCR and Southern blot hybridization, suggesting that bacteria from these soils have gene-mobilizing capacity with implications for the dissemination of resistance factors. Moreover, exogenous isolation of MGEs from the soil bacterial community was attempted under antibiotic selection pressure by using Escherichia coli as recipient. Seventeen putative transconjugants were identified based on increased antibiotic resistance. Metabolic traits and metal resistance of putative transconjugants were investigated, and whole genome sequencing was carried out for two of them. Most putative transconjugants displayed a multi-resistant phenotype for a broad spectrum of antibiotics. They also displayed changes regarding the ability to metabolise different carbon sources, RNA: DNA ratio, growth rate and biofilm formation. Genome sequencing of putative transconjugants failed to detect genes acquired by horizontal gene transfer, but instead revealed a number of nonsense mutations, including in ubiH, whose inactivation was linked to the observed resistance to aminoglycosides. Our results confirm that mine soils contain MGEs encoding antibiotic resistance. Moreover, they point out the role of spontaneous mutations in achieving low-level antibiotic resistance in a short time, which was associated with a trade-off in the capability to metabolise specific carbon sources. Copyright © 2017. Published by Elsevier B.V.
Challenges to a blow/fill/seal process with airborne microorganisms having different resistances to dry heat.

PubMed

Poisson, Patrick; Sinclair, Colin S; Tallentire, Alan

2006-01-01

Controlled challenges with air dispersed microorganisms having widely different resistances to dry heat, carried out on 624 BFS machine processing growth medium, have shown that higher the heat resistance, the greater the extent of vial contamination. Differences in heat resistance affected also the extent of vial contamination when parison and vial formation were knowingly manipulated through changes made to each of three process variables, provision of ballooning air, mould vacuum delay, and parison extrusion rate. The findings demonstrate that, in this investigational system, exposure of challenge micoorganisms to heat inherent in the process has a controlling influence on vial contamination, an influence that could also control microbiological risk in production environments.
Prevalence and antibiotic-resistance characteristics of Enterococcus spp. Isolated from free-living and captive raptors in Central Illinois.

PubMed

Marrow, Judilee; Whittington, Julia K; Mitchell, Mark; Hoyer, Lois L; Maddox, Carol

2009-04-01

Due to their predatory nature, raptor species may serve as important indicators of environmental contamination with antimicrobial-resistant bacteria. Raptors prey on small rodents and birds that have diverse habitat ranges, including urban and rural environments, and their intestinal microflora can reflect that of the animals on which they feed. Enterococcus spp. were selected as target organisms because they have been isolated from the avian gastrointestinal tract, can be conferred by prey items, and because they are capable of multiple resistance patterns. They are also a concerning source of human antimicrobial resistance. In this study fecal cultures were obtained from 15 May 2004 to 31 August 2004, from 21 free-living raptors and four captive raptors. Enterococcus was isolated from 21 (84%) of the 25 birds, and 54 isolates were chosen for further study based upon unique colony morphology. The most common isolate recovered was Enterococcus faecalis (95%, 95% confidence interval [CI]: 89-100). One bird in the study was determined to have Enterococcus gallinarum. Two distinct ribotypes of E. faecalis were identified, one with unique bands at 11 and 13 kb and the other with unique bands at 14 and 20 kb. Both ribotypes were found in free-living and captive birds. The Enterococcus isolates in this study demonstrated a variety of antimicrobial-resistance characteristics, including almost complete resistance to amikacin, first-generation cephalosporins, spectinomycin, and sulphadimethoxime. Isolates demonstrated variable resistance to chloramphenicol, gentamicin, enrofloxacin, erythromycin, and ticarcillin. No phenotypically vancomycin-resistant E. faecalis isolates were recovered from any of the raptors; three isolates had intermediate level susceptibility. A significantly higher number of isolates collected from captive birds demonstrated resistance to chloramphenicol than those obtained from free-living birds. This trend was not duplicated with any of the remaining 18 antimicrobial drugs tested. The results of this study suggest that raptors in central Illinois are coming into contact with antimicrobials, prey exposed to antimicrobials, or bacteria that are capable of transferring resistance genes. Further study is needed to determine the source of antimicrobial-resistant Enterococcus in free-living raptors but the limited data reflecting few differences between birds with and without antimicrobial exposure suggests that treatment and release of treated wild raptors is not contributing significantly to antimicrobial resistance in the environment.
Pollen contamination in seed mixture increases the dominance of resistance to Bt maize in Spodoptera frugiperda (Lepidoptera: Noctuidae).

PubMed

Yang, Fei; Kerns, David L; Brown, Sebe; Head, Graham P; Huang, Fangneng

2017-11-01

Seed mixture, also called 'RIB', has been used to provide refuge populations for delaying insect resistance. Pollen contamination in RIB could result in refuge kernels of non-Bt maize expressing variable Bt proteins. Data are lacking regarding the impact of pollen contamination on evolution of resistance for ear-feeding insects. Here, we used Spodoptera frugiperda and Cry1F-maize as a model to examine if pollen contamination in RIB increases the dominance of insect resistance. Pollen contamination caused >66% refuge kernels in 5:95% (non-Bt:Bt) and 20:80% RIBs to express Cry1F protein. Survival at adult stage on pure non-Bt ears was similar (54.4-63.3%) among Cry1F-susceptible (SS), Cry1F-resistant (RR) and Cry1F-heterozygous (RS) S. frugiperda. On Bt ears, survival was similar between SS and RS (0.0-1.7%), but it was significantly less than that of RR (59.2%). On the two RIB refuge ears, survival at adult stage for RS (42.3% in 5:95% RIB; 50.0% in 20:80% RIB) was significantly higher than for SS (8.7% in 5:95% RIB; 10.0% in 20:80% RIB). The results suggest that pollen contamination in RIB could increase the dominance of resistance for ear-feeding insects by significantly reducing susceptible refuge populations and supporting higher survival of heterozygotes relative to homozygous susceptible insects. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
Prevalence of antibacterial resistant bacterial contaminants from mobile phones of hospital inpatients.

PubMed

Kumar, B Vinod; Hobani, Yahya Hasan; Abdulhaq, Ahmed; Jerah, Ahmed Ali; Hakami, Othman M; Eltigani, Magdeldin; Bidwai, Anil K

2014-01-01

Mobile phones contaminated with bacteria may act as fomites. Antibiotic resistant bacterial contamination of mobile phones of inpatients was studied. One hundred and six samples were collected from mobile phones of patients admitted in various hospitals in Jazan province of Saudi Arabia. Eighty-nine (83.9%) out of 106 mobile phones were found to be contaminated with bacteria. Fifty-two (49.0%) coagulase-negative Staphylococcus, 12 (11.3%) Staphylococcus aureus, 7 (6.6%) Enterobacter cloacae, 3 (2.83%) Pseudomonas stutzeri, 3 (2.83%) Sphingomonas paucimobilis, 2 (1.8%) Enterococcus faecalis and 10 (9.4%) aerobic spore bearers were isolated. All the isolated bacteria were found to be resistant to various antibiotics. Hence, regular disinfection of mobile phones of hospital inpatients is advised.
Immobilization of Rhodococcus rhodochrous BX2 (an acetonitrile-degrading bacterium) with biofilm-forming bacteria for wastewater treatment.

PubMed

Li, Chunyan; Li, Yue; Cheng, Xiaosong; Feng, Liping; Xi, Chuanwu; Zhang, Ying

2013-03-01

In this study, a unique biofilm consisting of three bacterial strains with high biofilm-forming capability (Bacillus subtilis E2, E3, and N4) and an acetonitrile-degrading bacterium (Rhodococcus rhodochrous BX2) was established for acetonitrile-containing wastewater treatment. The results indicated that this biofilm exhibited strong resistance to acetonitrile loading shock and displayed a typical spatial and structural heterogeneity and completely depleted the initial concentration of acetonitrile (800mgL(-1)) within 24h in a moving-bed-biofilm reactor (MBBR) after operation for 30days. The immobilization of BX2 cells in the biofilm was confirmed by PCR-DGGE. It has been demonstrated that biofilm-forming bacteria can promote the immobilization of contaminant-degrading bacteria in the biofilms and can subsequently improve the degradation of contaminants in wastewater. This approach offers a novel strategy for enhancing biological oxidation of toxic pollutants in wastewater. Copyright © 2012 Elsevier Ltd. All rights reserved.
Evaluation of 2D resistivity imaging technique for delineating subsurface seepage of hydrocarbon-contaminated water southeast of Karbala city, Iraq.

PubMed

Al-Menshed, Firas H; Thabit, Jassim M

2017-03-01

2D imaging technique was applied in (8) transects near a pit of contaminated water near contaminated well southeast of Karbala city, Iraq. Each transect was 30 m long with 1 m electrode spacing. Data acquisition was fulfilled by using Wenner electrode array. The resistivity of water-contaminated zone is found less than 3Ω.m and the top dry zone recorded relatively high resistivity (more than 170Ω.m). It is found that the greatest amount of seepage was found moving towards northeast direction coincided with groundwater movement direction, whereas there was no movement towards northwest and southeast directions and restricted on the closest areas to the pit location. The outcomes suggested that the 2D imaging technique is a successful and powerful tool in separating contaminated zone from clear one and in detecting underground seepage depth and moving direction.
Characterization of metal-resistant plant-growth promoting Bacillus weihenstephanensis isolated from serpentine soil in Portugal.

PubMed

Rajkumar, Mani; Ma, Ying; Freitas, Helena

2008-12-01

A metal-resistant bacterial strain SM3 isolated from a serpentine soil in the north-east of Portugal was characterized as Bacillus weihenstephanensis based on the morphological and biochemical characteristics and on the comparative analysis of the partial 16S ribosomal DNA sequence. Bacillus weihenstephanensis SM3 showed a high degree of resistance to nickel (1500 mg l(-1)), copper (500 mg l(-1)) and zinc (700 mg l(-1)) and also to antibiotics (ampicillin, penicillin, kanamycin and streptomycin). Strain SM3 has also exhibited the capability of solubilizing phosphate and producing indole-3-acetic acid (IAA) both in the absence and in the presence of metals (Ni, Cu and Zn). A pot experiment was conducted to elucidate the effects of strain SM3 on plant growth and uptake of Ni, Cu or Zn by Helianthus annuus. Inoculation with strain SM3 increased the shoot and root biomass of H. annuus grown in both non-contaminated and contaminated soil. Furthermore, strain SM3 increased the accumulation of Cu and Zn in the root and shoot systems. A batch experiment was also conducted to assess the metal mobilization potential of strain SM3 in soil. Inoculation with this strain increased the concentrations of water soluble Ni, Cu and Zn in soil. Metal solubilization by this bacterial strain may be an important process to promote the uptake of heavy metals by plants. This study elucidates the multifarious role of strain SM3 in plant growth promotion and its metal mobilizing potential.
State Waste Discharge Permit Application: Electric resistance tomography testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1994-04-01

This permit application documentation is for a State Waste Discharge Permit issued in accordance with requirements of Washington Administrative Code 173-216. The activity being permitted is a technology test using electrical resistance tomography. The electrical resistance tomography technology was developed at Lawrence Livermore National Laboratory and has been used at other waste sites to track underground contamination plumes. The electrical resistance tomography technology measures soil electrical resistance between two electrodes. If a fluid contaminated with electrolytes is introduced into the soil, the soil resistance is expected to drop. By using an array of measurement electrodes in several boreholes, the arealmore » extent of contamination can be estimated. At the Hanford Site, the purpose of the testing is to determine if the electrical resistance tomography technology can be used in the vicinity of large underground metal tanks without the metal tank interfering with the test. It is anticipated that the electrical resistance tomography technology will provide a method for accurately detecting leaks from the bottom of underground tanks, such as the Hanford Site single-shell tanks.« less
ADAPTIVE MONITORING TO ENHANCE WATER SENSOR CAPABILITIES FOR CHEMICAL AND BIOLOGICAL CONTAMINANT DETECTION IN DRINKING WATER SYSTEMS

EPA Science Inventory

Optoelectronic and other conventional water quality sensors offer a potential for real-time online detection of chemical and biological contaminants in a drinking water supply and distribution system. The nature of the application requires sensors of detection capabilities at lo...
The reactive bed plasma system for contamination control

NASA Technical Reports Server (NTRS)

Birmingham, Joseph G.; Moore, Robert R.; Perry, Tony R.

1990-01-01

The contamination control capabilities of the Reactive Bed Plasma (RBP) system is described by delineating the results of toxic chemical composition studies, aerosol filtration work, and other testing. The RBP system has demonstrated its capabilities to decompose toxic materials and process hazardous aerosols. The post-treatment requirements for the reaction products have possible solutions. Although additional work is required to meet NASA requirements, the RBP may be able to meet contamination control problems aboard the Space Station.
A molecular epidemiological study of methicillin-resistant Staphylococci environmental contamination in railway stations and coach stations in Guangzhou of China.

PubMed

Lin, J L; Peng, Y; Ou, Q T; Lin, D X; Li, Y; Ye, X H; Zhou, J L; Yao, Z J

2017-02-01

Methicillin-resistant Staphylococcus aureus (MRSA) has caused a series of public health problems since it was first found in 1961. However, there are few research studies on the MRSA environmental contamination in railway stations and coach stations. Therefore, the aim of this study was to determine MRSA environmental contamination in public transport stations. Between December 2013 and January 2014, 380 surface samples from three railway stations (180) and four coach stations (200) in Guangzhou were collected to isolate and determine the prevalence and characteristics of Staphylococci strains. 39·21% of all samples were Staphylococci isolates, 1·58% of Staphylococci isolates were MRSA isolates, and 6·05% were methicillin-susceptible S. aureus. The proportion of multidrug resistant among 149 Staphylococci isolates was 75·84%. None of MRSA isolates was identified with the Panton-Valentine Leukocidin (PVL) genes, and one of them was identified with the qac gene. Four MRSA isolates were Staphylococcal Cassette Chromosome mec IVa, and the other two were nontypeable. Staphylococcus aureus isolates were classified into several sequence types (STs), and STs showed possible cross-transmissions of isolates from various sources. Methicillin-resistant Staphylococci contamination prevalence was high, and the environment of stations may be the vectors transmitting the Staphylococci to passengers. This is the first study to comprehensively report the prevalence, antibiotic resistance, and molecular characteristics of contamination of Staphylococci isolates in railway stations and coach stations of China. It will have great public health implications on infection control in community settings because of the serious hazard of Staphylococci, especially methicillin-resistant Staphylococci. Our findings have provided evidence for relevant departments to reduce the contamination of Staphylococci in environment of public transport stations. © 2016 The Society for Applied Microbiology.
Prevalence of antibacterial resistant bacterial contaminants from mobile phones of hospital inpatients

PubMed Central

Vinod Kumar, B.; Hobani, Yahya Hasan; Abdulhaq, Ahmed; Jerah, Ahmed Ali; Hakami, Othman M.; Eltigani, Magdeldin; Bidwai, Anil K.

2014-01-01

Mobile phones contaminated with bacteria may act as fomites. Antibiotic resistant bacterial contamination of mobile phones of inpatients was studied. One hundred and six samples were collected from mobile phones of patients admitted in various hospitals in Jazan province of Saudi Arabia. Eighty-nine (83.9%) out of 106 mobile phones were found to be contaminated with bacteria. Fifty-two (49.0%) coagulase-negative Staphylococcus, 12 (11.3%) Staphylococcus aureus, 7 (6.6%) Enterobacter cloacae, 3 (2.83%) Pseudomonas stutzeri, 3 (2.83%) Sphingomonas paucimobilis, 2 (1.8%) Enterococcus faecalis and 10 (9.4%) aerobic spore bearers were isolated. All the isolated bacteria were found to be resistant to various antibiotics. Hence, regular disinfection of mobile phones of hospital inpatients is advised. PMID:25292217

Public health implications of contamination of Franc CFA (XAF) circulating in Buea (Cameroon) with drug resistant pathogens.

PubMed

Akoachere, Jane-Francis Tatah Kihla; Gaelle, Nana; Dilonga, Henry Meriki; Nkuo-Akenji, Theresa K

2014-01-08

Studies in different parts of the world have implicated money as a vehicle for transmission of pathogens. Such information which is necessary to facilitate infection control strategies is lacking in many sub-Saharan countries including Cameroon. This study analyzed the Franc de la Communauté Financiere d'Afrique (Franc CFA), the currency used in Cameroon and other countries in the Central African sub-region, as a potential vehicle for transmission of pathogenic bacteria and fungi, particularly drug-resistant strains, to generate findings which could create awareness on currency contamination and serve as a guide when formulating health policies on currency. Two hundred and thirteen currency samples representing various denominations of notes and coins randomly collected from diverse sources in Buea, Cameroon were analyzed for bacteria and fungi. The sensitivity of bacterial isolates to antibiotics was tested using the disc diffusion method. The relationship between contamination and physical state, source or denomination of currency was assessed using the χ2 test. All statistics were discussed at 0.05 significance level. Two hundred (93.9%) samples were contaminated with notes (96.6%) showing higher contamination than coins (88.2%). Uncirculated (mint) samples showed no contamination. There was a significant difference (P<0.05) in contamination with respect to currency denomination, physical state and source. All samples from butchers and patients/personnel in hospitals were contaminated. Lower denominations showed significantly higher (P = 0.008) levels of contamination than higher denominations. Dirty currency was more contaminated than clean currency. Nine bacterial species were isolated. Coagulase-negative Staphylococcus (CoNS) (54.9%) and Staphylococcus aureus (20.1%) predominated. Among the fungi detected, Aspergillus sp (17.3%) and Penicillium sp (15.9%) showed higher frequency of occurrence. Bacteria were susceptible (100%) to ceftriaxone, gentamicin, norfloxacin and ofloxacin. Susceptibility to amoxicillin, penicillin, ampicillin, vancomycin and cotrimoxazole was low. Staphylococci were resistant (100%) to vancomycin, penicillin G, and amoxicillin. CoNS in addition showed resistance (100%) to cotrimoxazole. The CFA franc circulating in Buea could serve as a vehicle for transmission of drug resistant pathogenic or potential organisms and contamination could be due to currency usage and handling as mint notes were not contaminated. Hygiene practices during or after handling currency is greatly encouraged to prevent infection.
DELINEATION OF SUBSURFACE HYDROCARBON CONTAMINANT DISTRIBUTION USING A DIRECT PUSH RESISTIVITY METHOD

EPA Science Inventory

A direct push resistivity method was evaluated as a complementary screening tool to provide rapid in-situ contaminant detection to aid in better defining locations for drilling, sampling, and monitoring well installation at hazardous waste sites. Nine continuous direct push resi...
Microbial Functional Gene Diversity Predicts Groundwater Contamination and Ecosystem Functioning.

PubMed

He, Zhili; Zhang, Ping; Wu, Linwei; Rocha, Andrea M; Tu, Qichao; Shi, Zhou; Wu, Bo; Qin, Yujia; Wang, Jianjun; Yan, Qingyun; Curtis, Daniel; Ning, Daliang; Van Nostrand, Joy D; Wu, Liyou; Yang, Yunfeng; Elias, Dwayne A; Watson, David B; Adams, Michael W W; Fields, Matthew W; Alm, Eric J; Hazen, Terry C; Adams, Paul D; Arkin, Adam P; Zhou, Jizhong

2018-02-20

Contamination from anthropogenic activities has significantly impacted Earth's biosphere. However, knowledge about how environmental contamination affects the biodiversity of groundwater microbiomes and ecosystem functioning remains very limited. Here, we used a comprehensive functional gene array to analyze groundwater microbiomes from 69 wells at the Oak Ridge Field Research Center (Oak Ridge, TN), representing a wide pH range and uranium, nitrate, and other contaminants. We hypothesized that the functional diversity of groundwater microbiomes would decrease as environmental contamination (e.g., uranium or nitrate) increased or at low or high pH, while some specific populations capable of utilizing or resistant to those contaminants would increase, and thus, such key microbial functional genes and/or populations could be used to predict groundwater contamination and ecosystem functioning. Our results indicated that functional richness/diversity decreased as uranium (but not nitrate) increased in groundwater. In addition, about 5.9% of specific key functional populations targeted by a comprehensive functional gene array (GeoChip 5) increased significantly ( P < 0.05) as uranium or nitrate increased, and their changes could be used to successfully predict uranium and nitrate contamination and ecosystem functioning. This study indicates great potential for using microbial functional genes to predict environmental contamination and ecosystem functioning. IMPORTANCE Disentangling the relationships between biodiversity and ecosystem functioning is an important but poorly understood topic in ecology. Predicting ecosystem functioning on the basis of biodiversity is even more difficult, particularly with microbial biomarkers. As an exploratory effort, this study used key microbial functional genes as biomarkers to provide predictive understanding of environmental contamination and ecosystem functioning. The results indicated that the overall functional gene richness/diversity decreased as uranium increased in groundwater, while specific key microbial guilds increased significantly as uranium or nitrate increased. These key microbial functional genes could be used to successfully predict environmental contamination and ecosystem functioning. This study represents a significant advance in using functional gene markers to predict the spatial distribution of environmental contaminants and ecosystem functioning toward predictive microbial ecology, which is an ultimate goal of microbial ecology. Copyright © 2018 He et al.
Reduction in infection risk through treatment of microbially contaminated surfaces with a novel, portable, saturated steam vapor disinfection system.

PubMed

Tanner, Benjamin D

2009-02-01

Surface-mediated infectious disease transmission is a major concern in various settings, including schools, hospitals, and food-processing facilities. Chemical disinfectants are frequently used to reduce contamination, but many pose significant risks to humans, surfaces, and the environment, and all must be properly applied in strict accordance with label instructions to be effective. This study set out to determine the capability of a novel chemical-free, saturated steam vapor disinfection system to kill microorganisms, reduce surface-mediated infection risks, and serve as an alternative to chemical disinfectants. High concentrations of Escherichia coli, Shigella flexneri, vancomycin-resistant Enterococcus faecalis (VRE), methicillin-resistant Staphylococcus aureus (MRSA), Salmonella enterica, methicillin-sensitive Staphylococcus aureus, MS2 coliphage (used as a surrogate for nonenveloped viruses including norovirus), Candida albicans, Aspergillus niger, and the endospores of Clostridium difficile were dried individually onto porous clay test surfaces. Surfaces were treated with the saturated steam vapor disinfection system for brief periods and then numbers of surviving microorganisms were determined. Infection risks were calculated from the kill-time data using microbial dose-response relationships published in the scientific literature, accounting for surface-to-hand and hand-to-mouth transfer efficiencies. A diverse assortment of pathogenic microorganisms was rapidly killed by the steam disinfection system; all of the pathogens tested were completely inactivated within 5 seconds. Risks of infection from the contaminated surfaces decreased rapidly with increasing periods of treatment by the saturated steam vapor disinfection system. The saturated steam vapor disinfection system tested for this study is chemical-free, broadly active, rapidly efficacious, and therefore represents a novel alternative to liquid chemical disinfectants.
Study of electrical resistivity on the location and identification of contamination

NASA Astrophysics Data System (ADS)

McCarty, B. D.

1985-12-01

Electrical resistance studies were conducted in two laboratory models to determine electrical resistivity relationships and to use those defined relationships to identify contamination spikes. A good correlation was established between resistance data and the composition of leachate and copper spiked leachate gelatin blocks under study. The major variable that could not be eliminated from this study which had the greatest effect on data was moisture content. This thesis contains a review of the theory and field application of electrical resistivity, a description of the experimental approach used, and a summary of the data collected.
Characterization of the Metabolically Modified Heavy Metal-Resistant Cupriavidus metallidurans Strain MSR33 Generated for Mercury Bioremediation

PubMed Central

Rojas, Luis A.; Yáñez, Carolina; González, Myriam; Lobos, Soledad; Smalla, Kornelia; Seeger, Michael

2011-01-01

Background Mercury-polluted environments are often contaminated with other heavy metals. Therefore, bacteria with resistance to several heavy metals may be useful for bioremediation. Cupriavidus metallidurans CH34 is a model heavy metal-resistant bacterium, but possesses a low resistance to mercury compounds. Methodology/Principal Findings To improve inorganic and organic mercury resistance of strain CH34, the IncP-1β plasmid pTP6 that provides novel merB, merG genes and additional other mer genes was introduced into the bacterium by biparental mating. The transconjugant Cupriavidus metallidurans strain MSR33 was genetically and biochemically characterized. Strain MSR33 maintained stably the plasmid pTP6 over 70 generations under non-selective conditions. The organomercurial lyase protein MerB and the mercuric reductase MerA of strain MSR33 were synthesized in presence of Hg2+. The minimum inhibitory concentrations (mM) for strain MSR33 were: Hg2+, 0.12 and CH3Hg+, 0.08. The addition of Hg2+ (0.04 mM) at exponential phase had not an effect on the growth rate of strain MSR33. In contrast, after Hg2+ addition at exponential phase the parental strain CH34 showed an immediate cessation of cell growth. During exposure to Hg2+ no effects in the morphology of MSR33 cells were observed, whereas CH34 cells exposed to Hg2+ showed a fuzzy outer membrane. Bioremediation with strain MSR33 of two mercury-contaminated aqueous solutions was evaluated. Hg2+ (0.10 and 0.15 mM) was completely volatilized by strain MSR33 from the polluted waters in presence of thioglycolate (5 mM) after 2 h. Conclusions/Significance A broad-spectrum mercury-resistant strain MSR33 was generated by incorporation of plasmid pTP6 that was directly isolated from the environment into C. metallidurans CH34. Strain MSR33 is capable to remove mercury from polluted waters. This is the first study to use an IncP-1β plasmid directly isolated from the environment, to generate a novel and stable bacterial strain useful for mercury bioremediation. PMID:21423734
Antibiotic resistance of microorganisms in agricultural soils in Russia

NASA Astrophysics Data System (ADS)

Danilova, N. V.; Galitskaya, P. Yu; Selivanovskaya, S. Yu

2018-01-01

Antibiotics are medicines that are widely used in livestock production not only for the prevention and treatment of infectious diseases, but also for accelerating the growth of animals. The application of manure for fertilizing agricultural soils leads to the entry into the soil ecosystem not only of the antibiotics themselves, but also the resistance genes to them. In this study, 30 samples of arable soils were tested for the presence of the tet(X) gene, which encodes bacterial resistance to antibiotics of the tetracycline group. Using real-time PCR, it was found that 27 out of 30 soil samples contained tet(X). 52% of these samples were heavily contaminated, 34% had a medium level of contamination and 14% were slightly contaminated by the resistance gene tet(X).
Leguminosae native nodulating bacteria from a gold mine As-contaminated soil: Multi-resistance to trace elements, and possible role in plant growth and mineral nutrition.

PubMed

Rangel, Wesley de M; de Oliveira Longatti, Silvia M; Ferreira, Paulo A A; Bonaldi, Daiane S; Guimarães, Amanda A; Thijs, Sofie; Weyens, Nele; Vangronsveld, Jaco; Moreira, Fatima M S

2017-10-03

Efficient N 2 -fixing Leguminosae nodulating bacteria resistant to As may facilitate plant growth on As-contaminated sites. In order to identify bacteria holding these features, 24 strains were isolated from nodules of the trap species Crotalaria spectabilis (12) and Stizolobium aterrimum (12) growing on an As-contaminated gold mine site. 16S rRNA gene sequencing revealed that most of the strains belonged to the group of α-Proteobacteria, being representatives of the genera Bradyrhizobium, Rhizobium, Inquilinus, Labrys, Bosea, Starkeya, and Methylobacterium. Strains of the first four genera showed symbiotic efficiency with their original host, and demonstrated in vitro specific plant-growth-promoting (PGP) traits (production of organic acids, indole-3-acetic-acid and siderophores, 1-aminocyclopropane-1-carboxylate deaminase activity, and Ca 3 (PO 4 ) 2 solubilization), and increased resistance to As, Zn, and Cd. In addition, these strains and some type and reference rhizobia strains exhibited a wide resistance spectrum to β-lactam antibiotics. Both intrinsic PGP abilities and multi-element resistance of rhizobia are promising for exploiting the symbiosis with different legume plants on trace-element-contaminated soils.
Groundwater contamination in the Roorkee area, India: 2D joint inversion of radiomagnetotelluric and direct current resistivity data

NASA Astrophysics Data System (ADS)

Yogeshwar, P.; Tezkan, B.; Israil, M.; Candansayar, M. E.

2012-01-01

The impact of sewage irrigation and groundwater contamination were investigated near Roorkee in north India using the Direct Current Resistivity (DCR) method and the Radiomagnetotelluric (RMT) method. Intensive field measurements were carried out in the vicinity of a waste disposal site, which was extensively irrigated with sewage water. For comparison a profile was investigated on a reference site, where no contamination was expected. In addition to conventional 1D and 2D inversion, the measured data sets were interpreted using a 2D joint inversion algorithm. The inversion results from the data obtained from the sewage irrigated site indicate a decrease of resistivity up to 75% in comparison with the reference site. The depth range from 5 to 15 m is identified as a shallow unconfined aquifer and the decreased resistivities are ascribed as the influence of contamination. Furthermore, a systematic increase in the resistivities of the shallow unconfined aquifer is detected as we move away from the waste disposal site. The advantages of both, the DCR and RMT methods, are quantitatively integrated by the 2D joint inversion of both data sets and lead to a joint model, which explains both data sets.
Plant protection by the recombinant, root-colonizing Pseudomonas fluorescens F113rifPCB strain expressing arsenic resistance: improving rhizoremediation.

PubMed

Ryan, R P; Ryan, D; Dowling, D N

2007-12-01

The present study was designed to evaluate the stable insertion and expression of an arsenic resistance operon in the rhizosphere competent, PCB degrading strain Pseudomonas fluorescens F113rifPCB (F113rifPCB) and to investigate its ability to protect plants from arsenic. Introduction of the clone pUM3 (arsRDABC) into F113rifPCB was carried out by triparental conjugation. The resultant arsenic resistant strain was screened through a number of phenotypic tests including ability to grow on biphenyl, its rhizosphere competence and plant protection potential. Insertion and expression of arsenic resistant operon arsRDABC (from plasmid R773) into F113rifPCB strain has allowed this strain to grow, colonize the root and degrade biphenyl (100 mmol l(-1)) in the presence of sodium arsenate concentrations of up to 11.5 mmol l(-1). The strain retains its ability to colonize the rhizosphere of plants and appears to provide seed germination protection to arsenic which is not seen by the wild type. Owing to the significantly improved growth characteristics of both this rhizobacterium and plant species, the use of F113rifPCB-ars endowed with arsenic resistance capabilities may be a promising strategy to remediate mixed organic metal-contaminated sites. These types of strain could be used in the inoculation of metal accumulation plants for phytoremediation.
A far-ultraviolet contamination-irradiation facility for in situ reflectance measurements

NASA Astrophysics Data System (ADS)

Meier, Steven R.; Tveekrem, June L.; Keski-Kuha, Ritva A. M.

1998-10-01

In this article, a contamination-irradiation facility designed to measure contamination effects on far-ultraviolet optical surfaces is described. An innovative feature of the facility is the capability of depositing a contaminant, photopolymerizing the contaminant with far-ultraviolet light, and measuring the reflectance of the contaminated sample, all in situ. In addition to describing the facility, we present far-ultraviolet reflectance measurements for a contaminated mirror.
SUPERFUND TREATABILITY CLEARINGHOUSE: FULL SCALE ROTARY KILN INCINERATOR FIELD TRIAL: PHASE I, VERIFICATION TRIAL BURN ON DIOXIN/HERBICIDE ORANGE CONTAMINATED SOIL

EPA Science Inventory

This treatability study reports on the results of one of a series of field trials using various remedial action technologies that may be capable of restoring Herbicide Orange (HO)XDioxin contaminated sites. A full-scale field trial using a rotary kiln incinerator capable of pro...
Genetic analysis of stress responses in soil bacteria for enhanced bioremediation of mixed contaminants. 1997 annual progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, K.K.

'To provide increased knowledge of stress responses of indigenous microbes at contaminated sites as well as using microbes as molecular probes for monitoring the performance and effectiveness of bioremediation, the authors propose to identify the stress-inducible genes and promoters from two soil bacteria, Deinococcus radiodurans and Sphingomonas F199. These organisms represent two phylogenetically distinct groups of soil bacteria, each of which has specific features of interest for bioremediation. D. radiodurans exhibits high resistance to external stress; F199 is a deep subsurface (Savannah River Site) organism with unique degradative capabilities. Research Statement To realize the full potential of bioremediation, an understandingmore » of microbial community and individual bacterial responses to the stresses encountered at contaminated sites is needed. Knowledge about genetic responses of soil and subsurface bacteria to environmental stresses, which include low nutrients, low oxygen, and mixed pollutants, will allow extrapolation of basic principles to field applications either using indigenous bacteria or genetically engineered microorganisms. Defining bacterial responses to those stresses presents an opportunity for improving bioremediation strategies, and should contribute to environmental management and restoration actions that would reduce the cost and time required to achieve DOE''s cleanup goals.'« less
Capabilities of the Materials Contamination Team at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Burns, Howard; Albyn, Keith; Edwards, David; Boothe, Richard; Finchum, Charles; Finckenor, Miria

2003-01-01

The Materials Contamination Team at the Marshall Space Flight Center (MSFC) has been recognized for its contributions supporting the National Aeronautics and Space Administration (NASA) spacecraft development programs. These programs include the Reusable Solid Rocket Motor (RSRM), Chandra X-Ray Observatory, and the International Space Station (ISS). The Environmental Effects Group, with the Materials Contamination Team and the Space Environmental Effects Team has been an integral part of NASA's success by the testing, evaluation, and qualification of materials, hardware, and processes. This paper focuses on the capabilities of the Materials Contamination Team. The Materials Contamination Team's realm of responsibility includes establishing contamination control during all phases of hardware development, including design, manufacturing, assembly, test, transportation, launch site processing, on-orbit exposure, return, and refurbishment. The team continues its mission of reducing the risk of equipment failure due to molecular or particulate contamination. Contamination is a concern in the Space Shuttle with sensitive bond-lines and reactive fluid (liquid oxygen) compatibility as well as for spacecraft with sensitive optics, such as Hubble Space Telescope and Chandra X-ray Observatory. The Materials Contamination Team has a variety of facilities and instrumentation capable of contaminant detection, identification, and monitoring. The team addresses material applications dealing with environments, including production facilities, clean rooms, and on-orbit exposure. The optically stimulated electron emission (OSEE) system, the Ultraviolet (UV) fluorescence (UVF) surface contamination detection, and the Surface Optics Corporation 400 (SOC 400) portable hand-held Fourier Transform Infrared (FTIR) spectrometer are state-of-the-art tools for in-process molecular contamination detection. The team of engineers and technicians also develop contamination calibration standards and evaluate new surface cleanliness inspection technologies. The team utilizes facilities for on-orbit simulation testing of materials for outgassing and molecular film deposition characteristics in the presence of space environmental effects, such as Atomic Oxygen (AO) and UV radiation exposure. The Materials Contamination Team maintains databases for process materials as well as outgassing and optical compatibility test results for specific environments.
Contamination of the Clinical Microbiology Laboratory with Vancomycin-Resistant Enterococci and Multidrug- Resistant Enterobacteriaceae: Implications for Hospital and Laboratory Workers

PubMed Central

Collins, Susan M.; Hacek, Donna M.; Degen, Lisa A.; Wright, Marc O.; Noskin, Gary A.; Peterson, Lance R.

2001-01-01

We surveyed environmental surfaces in our clinical microbiology laboratory to determine the prevalence of vancomycin-resistant enterococci (VRE) and multidrug-resistant Enterobacteriaceae (MDRE) during a routine working day. From a total of 193 surfaces, VRE were present on 20 (10%) and MDRE were present on 4 (2%) of the surfaces tested. In a subsequent survey after routine cleaning, all of the 24 prior positive surfaces were found to be negative. Thus, those in the laboratory should recognize that many surfaces may be contaminated by resistant organisms during routine processing of patient specimens. PMID:11574615
Geophysical investigation at an existing landfill, Badger Army Ammunition Plant, Baraboo, Wisconsin. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitten, C.B.; Sjostrom, K.J.

1991-04-01

Ground-water contaminants were found in ground-water monitoring wells at the existing landfill. More wells to define the horizontal and vertical extent of the contaminant plume are to be installed. Geophysical techniques (electro-magnetic induction, vertical electrical resistivity, and horizontal resistivity profiling) were used to map the extent of the contaminant plume. Using the geophysical, ground-water elevation, and geologic data, five anomalous areas south and east of the landfill were identified as locations for additional ground-water monitoring wells.
Shuttle filter study. Volume 3: Appendix

NASA Technical Reports Server (NTRS)

1974-01-01

Test data obtained from flow resistance and contaminant tolerance tests on the various porous media evaluated in the different fluids are presented in both graphical and tabular forms. Test procedures for both flow resistance and contaminant tolerance testing are presented, and the development of a system for continuously adding contaminant at a predetermined rate to a flowing fluid stream is described. Also included is a section describing the development effort of the self-indexing filter. This concept was adapted during this program for various shuttle applications.
Metabolomics analysis of the effect of elevated co2 on wheat resistance to Fusarium head blight

USDA-ARS?s Scientific Manuscript database

Climate change is expected to intensify Fusarium head blight (FHB) contamination of wheat and increase the associated risk of mycotoxin contamination in food and feed. Rising CO2 levels are part of climate change with still unknown effects on natural wheat resistance mechanisms against Fusarium gram...
Effect of cationic contaminants on polymer electrolyte fuel cell performance

NASA Astrophysics Data System (ADS)

Qi, Jing; Wang, Xiaofeng; Ozdemir, M. Ozan; Uddin, Md. Aman; Bonville, Leonard; Pasaogullari, Ugur; Molter, Trent

2015-07-01

The effect of cationic contaminants on polymer electrolyte fuel cell (PEFC) performance is investigated via in-situ injection of dilute cationic salt solutions. Four foreign cations (K+, Ba2+, Ca2+, Al3+) are chosen as contaminants in this study due to their prevalence and chemical structure (e.g. valence), however contaminants that have already received extensive coverage in the literature like sodium and iron are excluded. It is found that the cells with Ba(ClO4)2 and Ca(ClO4)2 injection exhibit little cell performance change during the current hold test, and the cells with Al(ClO4)3 and KClO4 injection show larger cell performance changes, i.e. decreasing cell voltage and increasing cell resistance. These cells with in-situ contaminant injection have a tendency to recover a portion of the lost performance after the recovery test when switched back to supersaturated air. The degradation in cell performance with the presence of cationic contaminants is mainly due, in addition to the membrane resistance increase associated with replacing protons on the sulfonate groups, to the increase in mass transport resistance and decrease in electrochemical surface area.
Characterizing leachate contamination in a landfill site using Time Domain Electromagnetic (TDEM) imaging

NASA Astrophysics Data System (ADS)

Baawain, Mahad S.; Al-Futaisi, Ahmed M.; Ebrahimi, A.; Omidvarborna, Hamid

2018-04-01

Time Domain Electromagnetic (TDEM) survey as well as drilling investigations were conducted to identify possible contamination of a dumping site in an unsaturated zone located in Barka, Oman. The method was applied to evaluate conductivity of the contaminated plumes in hot and arid/semiarid region, where high temperatures commonly ranged between 35 and 50 °C. The drilling investigation was carried out over the survey area to verify the geophysical results. The low-resistivity zone (<80 Ωm), encountered near the subsurface, indicated plume migration caused by liquid waste disposal activities. The combination of TDEM survey results with the lithology of piezometers showed that higher resistivity (>90 Ωm) was correlated with compacted or cemented gravels and cobbles, particularly that of medium dense to very dense gravels and cobbles. Additionally, the TDEM profiles suggested that the plume migration followed a preferential flow path. The resistivity range 40-80 Ωm considered as contaminated areas; however, the drilling results showed the close resistivity domain in the depth >70 m below water table for some profiles (BL1, BL2, BL3, BL4 and BL5). The combined results of drilling wells, piezometers, and TDEM apparent resistivity maps showed a coincidence of the migrated leachate plume and water table. Predicted zone of the probable contamination was located at the depth of around 65 m and horizontal offset ranges 0-280 m, 80-240 m, and 40-85 m in the sounding traverses of BL4, BL6 and BL7, respectively.

MULTIPLE CONTAMINANT ISSUES AND TECHNOLOGIES

EPA Science Inventory

The presentation provides information on the removal of arsenic with either nitrate, uranium, radium, radon and antimony as a co-contaminant. The technologies discussed as having the capability of removing arsenic and one of the other contaminants are reverse osmosis, anion and ...
SUPERFUND TREATABILITY CLEARINGHOUSE: FULL ...

EPA Pesticide Factsheets

This treatability study reports on the results of one of a series of field trials using various remedial action technologies that may be capable of restoring Herbicide Orange (HO)XDioxin contaminated sites. A full-scale field trial using a rotary kiln incinerator capable of processing up to 6 tons per hour of dioxin contaminated soil was conducted at the Naval Construction Battalion Center, Gulfport, MS. publish information
Application of 4D resistivity image profiling to detect DNAPLs plume.

NASA Astrophysics Data System (ADS)

Liu, H.; Yang, C.; Tsai, Y.

2008-12-01

In July 1993, the soil and groundwater of the factory of Taiwan , Miaoli was found to be contaminated by dichloroethane, chlorobenzene and other hazardous solvents. The contaminants were termed to be dense non-aqueous phase liquids (DNAPLs). The contaminated site was neglected for the following years until May 1998, the Environment Protection Agency of Miaoli ordered the company immediately take an action for treatment of the contaminated site. Excavating and exposing the contaminated soil was done at the previous waste DNAPL dumped area. In addition, more than 53 wells were drilled around the pool with a maximum depth of 12 m where a clayey layer was found. Continuous pumping the groundwater and monitoring the concentration of residual DNAPL contained in the well water samples have done in different stages of remediation. However, it is suspected that the DNAPL has existed for a long time, therefore the contaminants might dilute but remnants of a DNAPL plume that are toxic to humans still remain in the soil and migrate to deeper aquifers. A former contaminated site was investigated using the 2D, 3D and 4D resisitivity image technique, with aims of determining buried contaminant geometry. This paper emphasizes the use of resistivity image profiling (RIP) method to map the limit of this DNAPL waste disposal site where the records of operations are not variations. A significant change in resistivity values was detected between known polluted and non-polluted subsurface; a high resistivity value implies that the subsurface was contaminated by DNAPL plume. The results of the survey serve to provide insight into the sensitivity of RIP method for detecting DNAPL plumes within the shallow subsurface, and help to provide valuable information related to monitoring the possible migration path of DNAPL plume in the past. According to the formerly studies in this site, affiliation by excavates with pumps water remediation had very long time, Therefore this research was used iron nanoparticles with pumps water remediation ways. The survey lines use the same length and the same position of the different time observation. The survey lines monitors the iron nanoparticles and pollution flow direction with remediation effect. By used the iron nanoparticles and pumping water remediation ways, the DNAPL plumes had eminent changed. Iron nanoparticles granule is smaller than the micron iron, Therefore the reaction rate was quite quick at the iron nanoparticles and pumps, but the ferric oxide can cause the electronic resistivity to elevate produces after the response. Pumps water rectifies may remove the ferric oxide to cause the electronic resistivity to reduce. The iron nanoparticles and pollution response is extremely obviously of the Resistivity Image Profile.
Microbial contamination of mobile phones in a health care setting in Alexandria, Egypt.

PubMed

Selim, Heba Sayed; Abaza, Amani Farouk

2015-01-01

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

PubMed Central

Selim, Heba Sayed; Abaza, Amani Farouk

2015-01-01

Aim: This study aimed at investigating the microbial contamination of mobile phones in a hospital setting. Methods: Swab samples were collected from 40 mobile phones of patients and health care workers at the Alexandria University Students’ Hospital. They were tested for their bacterial contamination at the microbiology laboratory of the High Institute of Public Health. Quantification of bacteria was performed using both surface spread and pour plate methods. Isolated bacterial agents were identified using standard microbiological methods. Methicillin-resistant Staphylococcus aureus was identified by disk diffusion method described by Bauer and Kirby. Isolated Gram-negative bacilli were tested for being extended spectrum beta lactamase producers using the double disk diffusion method according to the Clinical and Laboratory Standards Institute recommendations. Results: All of the tested mobile phones (100%) were contaminated with either single or mixed bacterial agents. The most prevalent bacterial contaminants were methicillin-resistant S. aureus and coagulase-negative staphylococci representing 53% and 50%, respectively. The mean bacterial count was 357 CFU/ml, while the median was 13 CFU/ml using the pour plate method. The corresponding figures were 2,192 and 1,720 organisms/phone using the surface spread method. Conclusions: Mobile phones usage in hospital settings poses a risk of transmission of a variety of bacterial agents including multidrug-resistant pathogens as methicillin-resistant S. aureus. The surface spread method is an easy and useful tool for detection and estimation of bacterial contamination of mobile phones. PMID:25699226
Inoculation of Ni-resistant plant growth promoting bacterium Psychrobacter sp. strain SRS8 for the improvement of nickel phytoextraction by energy crops.

PubMed

Ma, Y; Rajkumar, M; Vicente, J A F; Freitas, H

2011-02-01

This study was conducted to elucidate effects of inoculating plant growth-promoting bacterium Psychrobacter sp. SRS8 on the growth and phytoextraction potential of energy crops Ricinus communis and Helianthus annuus in artificially Ni contaminated soils. The toxicity symptom in plants under Ni stress expressed as chlorophyll, protein content, growth inhibition, and Fe, P concentrations were studied, and the possible relationship among them were also discussed. The PGPB SRS8 was found capable of stimulating plant growth and Ni accumulation in both plant species. Further, the stimulation effect on plant biomass, chlorophyll, and protein content was concomitant with increased Fe and P assimilation from soil to plants. Further, the induction of catalase and peroxidase activities was also involved in the ability of SRS8 to increase the tolerance in both plant species under Ni stress. The findings suggest that strain SRS8 play an important role in promoting the growth and phytoextraction efficiency of R. communis and H. annuus, which may be used for remediation of metal contaminated sites.
Microbial remediation of soils co-contaminated with 2,4-dichlorophenoxyacetic acid and cadmium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roane, T.M.; Pepper, I.L.

1997-12-31

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

PubMed

Schütze, Eileen; Klose, Michael; Merten, Dirk; Nietzsche, Sandor; Senftleben, Dominik; Roth, Martin; Kothe, Erika

2014-02-28

The impact of the extremely heavy metal resistant actinomycete Streptomyces mirabilis P16B-1 on heavy metal mobilization/stabilization, phytoremediation and stress level of plants was analyzed in the presence and absence of Sorghum bicolor in sterile microcosms containing highly metal contaminated or control soil. For control, a metal sensitive S. lividans TK24 was used. The metal contents with respect to the mobile and specifically adsorbed fractions of the contaminated soil were considerably decreased by addition of both, living and dead biomass of the strains, with the heavy metal resistant S. mirabilis P16B-1 showing considerably higher impact. Both strains could grow in control soil, while only S. mirabilis P16B-1 formed new tip growth in the metal contaminated soil. A plant growth promoting effect was visible for S. mirabilis P16B-1 in contaminated soil enhancing the dry weight of inoculated Sorghum plants. Thus, metal resistant strains like S. mirabilis P16B-1 are able to enhance phytoremediation of heavy metal contaminated soils. Copyright © 2013 Elsevier B.V. All rights reserved.
Effective Antibiotic Resistance Mitigation during Cheese Fermentation ▿

PubMed Central

Li, Xinhui; Li, Yingli; Alvarez, Valente; Harper, Willis James; Wang, Hua H.

2011-01-01

Controlling antibiotic-resistant (ART) bacteria in cheese fermentation is important for food safety and public health. A plant-maintained culture was found to be a potential source for ART bacterial contamination in cheese fermentation. Antibiotics had a detectable effect on the ART population from contamination in the finished product. The decrease in the prevalence of antibiotic resistance (AR) in retail cheese samples from 2010 compared to data from 2006 suggested the effectiveness of targeted AR mitigation in related products. PMID:21784910
Fingerprints of resistant Escherichia coli O157:H7 from vegetables and environmental samples

USDA-ARS?s Scientific Manuscript database

In the last decade, increases in E. coli O157:H7 outbreaks linked to fresh produce had been associated with contaminated irrigation water. However, studies on antibiotics resistance in E. coli associated with fresh produce impacted by contaminated water in Nigeria is very limited. The aim of this st...
CONTAMINANTS AND REMEDIAL OPTIONS AT SELECTED METAL-CONTAMINATED SITES

EPA Science Inventory

This document provides information that facilitates characterization of the site and selection of treatment technologies at metals-contaminated sites that would be capable of meeting site-specific cleanup levels. he document does not facilitate the determination of cleanup levels...
INNOVATIVE PROCESSES FOR RECLAMATION OF CONTAMINATED SUBSURFACE ENVIRONMENTS

EPA Science Inventory

Research to better assess the capabilities and limitations of fixed-film bioreactors for removing selected organic contaminants from ground water or from contaminated vapor streams produced by air stripping of polluted ground water and by soil venting operations is described. ...
[Effects of carbon sources changes on the property and morphology of 2,4-D degraded aerobic sludge granules].

PubMed

Ma, Jing-Yun; Quan, Xian-Chun; Xiong, Wei-Cong

2010-11-01

This study investigated the changes of the morphology, structure, and capability of removing the target contamination of the aerobic granules pre-cultured with mixed substrates of glucose and 2,4-dichlorophenoxyacetic acid (2,4-D) in a long-time running sequence batch reactor (SBR), when the carbon source transformed into the sole carbon source of 2,4-D. Results showed that when the substrate turned to the sole carbon source of 2,4-D, the aerobic granules still maintained a strong degradation ability to the target contamination; a 2,4-D removal percentage of 99.2% -100% and an average COD removal rate of 85.6% were achieved at the initial 2,4-D concentration of 361-564 mg/L. Carbon source transformation caused certain damages to the original aerobic granule structure, made some parts of granules disintegrated, and led to granule size decline from 513 microm to 302 microm. However, those granules maintained the main body, re-aggregated and grew after a period of adaptation due to their strong resistance to toxicity. Aerobic granules capable of utilizing 2,4-D as the sole carbon source with a good settling ability (SYI 20-40 mL/g) and a mean diameter of 489 microm were finally obtained in this study. Scanning electron microscope (SEM) observation showed that the diversity of granule microbial species was declined when turned to the sole carbon source.
Decontamination of Anthrax spores in critical infrastructure and critical assets.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boucher, Raymond M.; Crown, Kevin K.; Tucker, Mark David

2010-05-01

Decontamination of anthrax spores in critical infrastructure (e.g., subway systems, major airports) and critical assets (e.g., the interior of aircraft) can be challenging because effective decontaminants can damage materials. Current decontamination methods require the use of highly toxic and/or highly corrosive chemical solutions because bacterial spores are very difficult to kill. Bacterial spores such as Bacillus anthracis, the infectious agent of anthrax, are one of the most resistant forms of life and are several orders of magnitude more difficult to kill than their associated vegetative cells. Remediation of facilities and other spaces (e.g., subways, airports, and the interior of aircraft)more » contaminated with anthrax spores currently requires highly toxic and corrosive chemicals such as chlorine dioxide gas, vapor- phase hydrogen peroxide, or high-strength bleach, typically requiring complex deployment methods. We have developed a non-toxic, non-corrosive decontamination method to kill highly resistant bacterial spores in critical infrastructure and critical assets. A chemical solution that triggers the germination process in bacterial spores and causes those spores to rapidly and completely change to much less-resistant vegetative cells that can be easily killed. Vegetative cells are then exposed to mild chemicals (e.g., low concentrations of hydrogen peroxide, quaternary ammonium compounds, alcohols, aldehydes, etc.) or natural elements (e.g., heat, humidity, ultraviolet light, etc.) for complete and rapid kill. Our process employs a novel germination solution consisting of low-cost, non-toxic and non-corrosive chemicals. We are testing both direct surface application and aerosol delivery of the solutions. A key Homeland Security need is to develop the capability to rapidly recover from an attack utilizing biological warfare agents. This project will provide the capability to rapidly and safely decontaminate critical facilities and assets to return them to normal operations as quickly as possible, sparing significant economic damage by re-opening critical facilities more rapidly and safely. Facilities and assets contaminated with Bacillus anthracis (i.e., anthrax) spores can be decontaminated with mild chemicals as compared to the harsh chemicals currently needed. Both the 'germination' solution and the 'kill' solution are constructed of 'off-the-shelf,' inexpensive chemicals. The method can be utilized by directly spraying the solutions onto exposed surfaces or by application of the solutions as aerosols (i.e., small droplets), which can also reach hidden surfaces.« less
Isolation and characterization of a chromium-resistant bacterium Serratia sp. Cr-10 from a chromate-contaminated site.

PubMed

Zhang, Kundi; Li, Fuli

2011-05-01

A novel bacterium, Cr-10, was isolated from a chromium-contaminated site and capable of removing toxic chromium species from solution by reducing hexavalent chromium to an insoluble precipitate. Sequence analysis of 16S rRNA gene of strain Cr-10 showed that it was most closely related to Serratia rubidaea JCM 1240(T) (97.68%). Physiological and chemotaxonomic data also supported that strain Cr-10 was identified as Serratia sp., a genus which was never specially reported chromate-resistant before. Serratia sp., Cr-10 was tolerant to a concentration of 1,500 mg Cr(VI) L(-1), which was the highest level reported until now. The optimum pH and temperature for reduction of Cr(VI) by Serratia sp. Cr-10 were found to be 7.0 and 37 °C, respectively. The Cr(VI) reduction was significantly influenced by additional carbon sources, and among them fructose and lactose offered maximum reduction, with a rate of 0.28 and 0.25 mg Cr(VI) L(-1) h(-1), respectively. The cell-free extracts and filtrate of the culture were able to reduce Cr(VI) while concentration of total chromium remained stable in the process, indicating that the enzyme-catalyzed mechanism was applied in Cr(VI) reduction by the isolate. Additionally, it was found that there was hardly any chromium on the cell surface of the strain, further supporting that reduction, rather than bioadsorption, plays a major role in the Cr(VI) removal.
Resistivity and self-potential tomography applied to groundwater remediation and contaminant plumes: Sandbox and field experiments

NASA Astrophysics Data System (ADS)

Mao, D.; Revil, A.; Hort, R. D.; Munakata-Marr, J.; Atekwana, E. A.; Kulessa, B.

2015-11-01

Geophysical methods can be used to remotely characterize contaminated sites and monitor in situ enhanced remediation processes. We have conducted one sandbox experiment and one contaminated field investigation to show the robustness of electrical resistivity tomography and self-potential (SP) tomography for these applications. In the sandbox experiment, we injected permanganate in a trichloroethylene (TCE)-contaminated environment under a constant hydraulic gradient. Inverted resistivity tomograms are able to track the evolution of the permanganate plume in agreement with visual observations made on the side of the tank. Self-potential measurements were also performed at the surface of the sandbox using non-polarizing Ag-AgCl electrodes. These data were inverted to obtain the source density distribution with and without the resistivity information. A compact horizontal dipole source located at the front of the plume was obtained from the inversion of these self-potential data. This current dipole may be related to the redox reaction occurring between TCE and permanganate and the strong concentration gradient at the front of the plume. We demonstrate that time-lapse self-potential signals can be used to track the kinetics of an advecting oxidizer plume with acceptable accuracy and, if needed, in real time, but are unable to completely resolve the shape of the plume. In the field investigation, a 3D resistivity tomography is used to characterize an organic contaminant plume (resistive domain) and an overlying zone of solid waste materials (conductive domain). After removing the influence of the streaming potential, the identified source current density had a magnitude of 0.5 A m-2. The strong source current density may be attributed to charge movement between the neighboring zones that encourage abiotic and microbially enhanced reduction and oxidation reactions. In both cases, the self-potential source current density is located in the area of strong resistivity gradient.
Prevalence and Antimicrobial Resistance of Enterococci Isolated from Retail Meats in the United States, 2002 to 2014.

PubMed

Tyson, Gregory H; Nyirabahizi, Epiphanie; Crarey, Emily; Kabera, Claudine; Lam, Claudia; Rice-Trujillo, Crystal; McDermott, Patrick F; Tate, Heather

2018-01-01

Bacteria of the genus Enterococcus are important human pathogens that are frequently resistant to a number of clinically important antibiotics. They are also used as markers of animal fecal contamination of human foods and are employed as sentinel organisms for tracking trends in resistance to antimicrobials with Gram-positive activity. As part of the National Antimicrobial Resistance Monitoring System (NARMS), we evaluated several retail meat commodities for the presence of enterococci from 2002 to 2014, and we found 92.0% to be contaminated. The majority of isolates were either Enterococcus faecalis (64.0%) or Enterococcus faecium (28.6%), and the antimicrobial resistance of each isolate was assessed by broth microdilution. The resistance prevalences for several drugs, including erythromycin and gentamicin, were significantly higher among poultry isolates, compared to retail beef or pork isolates. None of the isolates was resistant to the clinically important human drug vancomycin, only 1 isolate was resistant to linezolid, and resistance to tigecycline was below 1%. In contrast, a majority of both E. faecalis (67.5%) and E. faecium (53.7%) isolates were resistant to tetracycline. Overall, the robust NARMS testing system employed consistent sampling practices and methods throughout the testing period, with the only significant trend in resistance prevalence being decreased E. faecium resistance to penicillin. These data provide excellent baseline levels of resistance that can be used to measure future changes in resistance prevalence that may result from alterations in the use of antimicrobials in food animal production. IMPORTANCE Enterococci, including E. faecalis and E. faecium , are present in the guts of food-producing animals and are used as a measure of fecal contamination of meat. We used the large consistent sampling methods of NARMS to assess the prevalence of Enterococcus strains isolated from retail meats, and we found over 90% of meats to be contaminated with enterococci. We also assessed the resistance of the Enterococcus strains, commonly used as a measure of resistance to agents with Gram-positive activity, in foods. Resistance prevalence was over 25% for some antimicrobials and sample sources but was less than 1% for several of the most important therapeutic agents used in human medicine. This is a work of the U.S. Government and is not subject to copyright protection in the United States. Foreign copyrights may apply.
Public computer surfaces are reservoirs for methicillin-resistant staphylococci.

PubMed

Kassem, Issmat I; Sigler, Von; Esseili, Malak A

2007-07-01

The role of computer keyboards used by students of a metropolitan university as reservoirs of antibiotic-resistant staphylococci was determined. Putative methicillin (oxacillin)-resistant staphylococci isolates were identified from keyboard swabs following a combination of biochemical and genetic analyses. Of 24 keyboards surveyed, 17 were contaminated with staphylococci that grew in the presence of oxacillin (2 mg l(-1)). Methicillin (oxacillin)-resistant Staphylococcus aureus (MRSA), -S. epidermidis (MRSE) and -S. hominis (MRSH) were present on two, five and two keyboards, respectively, while all three staphylococci co-contaminated one keyboard. Furthermore, these were found to be part of a greater community of oxacillin-resistant bacteria. Combined with the broad user base common to public computers, the presence of antibiotic-resistant staphylococci on keyboard surfaces might impact the transmission and prevalence of pathogens throughout the community.
Expression Analysis of Stress-Related Genes in Kernels of Different Maize (Zea mays L.) Inbred Lines with Different Resistance to Aflatoxin Contamination

PubMed Central

Jiang, Tingbo; Zhou, Boru; Luo, Meng; Abbas, Hamed K.; Kemerait, Robert; Lee, Robert Dewey; Scully, Brian T.; Guo, Baozhu

2011-01-01

This research examined the expression patterns of 94 stress-related genes in seven maize inbred lines with differential expressions of resistance to aflatoxin contamination. The objective was to develop a set of genes/probes associated with resistance to A. flavus and/or aflatoxin contamination. Ninety four genes were selected from previous gene expression studies with abiotic stress to test the differential expression in maize lines, A638, B73, Lo964, Lo1016, Mo17, Mp313E, and Tex6, using real-time RT-PCR. Based on the relative-expression levels, the seven maize inbred lines clustered into two different groups. One group included B73, Lo1016 and Mo17, which had higher levels of aflatoxin contamination and lower levels of overall gene expression. The second group which included Tex6, Mp313E, Lo964 and A638 had lower levels of aflatoxin contamination and higher overall levels of gene expressions. A total of six “cross-talking” genes were identified between the two groups, which are highly expressed in the resistant Group 2 but down-regulated in susceptible Group 1. When further subjected to drought stress, Tex6 expressed more genes up-regulated and B73 has fewer genes up-regulated. The transcript patterns and interactions measured in these experiments indicate that the resistant mechanism is an interconnected process involving many gene products and transcriptional regulators, as well as various host interactions with environmental factors, particularly, drought and high temperature. PMID:22069724
Endophytic bacteria and their potential to enhance heavy metal phytoextraction.

PubMed

Rajkumar, Mani; Ae, Noriharu; Freitas, Helena

2009-09-01

Pollution of soils with heavy metals is becoming one of the most severe environmental and human health hazards. Due to its widespread contamination finding innovative ways to clean metal pollutant has become a priority in the remediation field. Phytoremediation, the use of plants for the restoration of environments contaminated with pollutants is a relatively new technology that is more benign than current engineering solutions to treat contaminated sites. Recently, the benefits of combining endophytic bacteria with plants for increased remediation of pollutants have been successfully tried for toxic metal removal from contaminated soils. Endophytic bacteria reside within plant hosts without causing disease symptoms. Further, the metal resistant endophytes are reported to be present in various hyperaccumulator plants growing on heavy metal contaminated soils and play an important role in successful survival and growth of plants. Moreover, the metal resistant endophytes are reported to promote plant growth by various mechanisms such as nitrogen fixation, solubilization of minerals, production of phytohormones, siderophores, utilization of 1-aminocyclopropane-1-carboxylic acid as a sole N source and transformation of nutrient elements. In this review we highlight the diversity and plant growth promoting features of metal resistant endophytic bacteria and discuss their potential in phytoextraction of heavy metals from contaminated soils.

ENGINEERING ISSUE: TECHNOLOGY ALTERNATIVES FOR THE REMEDIATION OF PCB-CONTAMINATED SOIL AND SEDIMENT

EPA Science Inventory

Because of the increased need for Superfund decision-makers to have a working knowledge of the remedial capabilities available to treat soil and sediment contaminated with polychlorinated biphenyls (PCBs), the Superfund Engineering Forum has identified remediation of PCB-contamin...
Resistivity profiling for mapping gravel layers that may control contaminant migration at the Amargosa Desert Research Site, Nevada

USGS Publications Warehouse

Lucius, Jeffrey E.; Abraham, Jared D.; Burton, Bethany L.

2008-01-01

Gaseous contaminants, including CFC 113, chloroform, and tritiated compounds, move preferentially in unsaturated subsurface gravel layers away from disposal trenches at a closed low-level radioactive waste-disposal facility in the Amargosa Desert about 17 kilometers south of Beatty, Nevada. Two distinct gravel layers are involved in contaminant transport: a thin, shallow layer between about 0.5 and 2.2 meters below the surface and a layer of variable thickness between about 15 and 30 meters below land surface. From 2003 to 2005, the U.S. Geological Survey used multielectrode DC and AC resistivity surveys to map these gravel layers. Previous core sampling indicates the fine-grained sediments generally have higher water content than the gravel layers or the sediments near the surface. The relatively higher electrical resistivity of the dry gravel layers, compared to that of the surrounding finer sediments, makes the gravel readily mappable using electrical resistivity profiling. The upper gravel layer is not easily distinguished from the very dry, fine-grained deposits at the surface. Two-dimensional resistivity models, however, clearly identify the resistive lower gravel layer, which is continuous near the facility except to the southeast. Multielectrode resistivity surveys provide a practical noninvasive method to image hydrogeologic features in the arid environment of the Amargosa Desert.
ERLN Water Focus Area

EPA Pesticide Factsheets

The Water Laboratory Alliance (WLA), within Environmental Response Laboratory Network, maintains analytical capability and capacity in the event of intentional and unintentional water contamination with chemical, biological and radiochemical contaminants.
Milk Contamination and Resistance to Processing Conditions Determine the Fate of Lactococcus lactis Bacteriophages in Dairies

PubMed Central

Madera, Carmen; Monjardín, Cristina; Suárez, Juan E.

2004-01-01

Milk contamination by phages, the susceptibility of the phages to pasteurization, and the high levels of resistance to phage infection of starter strains condition the evolution dynamics of phage populations in dairy environments. Approximately 10% (83 of 900) of raw milk samples contained phages of the quasi-species c2 (72%), 936 (24%), and P335 (4%). However, 936 phages were isolated from 20 of 24 (85%) whey samples, while c2 was detected in only one (4%) of these samples. This switch may have been due to the higher susceptibility of c2 to pasteurization (936-like phages were found to be approximately 35 times more resistant than c2 strains to treatment of contaminated milk in a plate heat exchanger at 72°C for 15 s). The restriction patterns of 936-like phages isolated from milk and whey were different, indicating that survival to pasteurization does not result in direct contamination of the dairy environment. The main alternative source of phages (commercial bacterial starters) does not appear to significantly contribute to phage contamination. Twenty-four strains isolated from nine starter formulations were generally resistant to phage infection, and very small progeny were generated upon induction of the lytic cycle of resident prophages. Thus, we postulate that a continuous supply of contaminated milk, followed by pasteurization, creates a factory environment rich in diverse 936 phage strains. This equilibrium would be broken if a particular starter strain turned out to be susceptible to infection by one of these 936-like phages, which, as a consequence, became prevalent. PMID:15574937
Surveillance of bacterial contamination in small animal veterinary hospitals with special focus on antimicrobial resistance and virulence traits of enterococci.

PubMed

KuKanich, Kate S; Ghosh, Anuradha; Skarbek, Jennifer V; Lothamer, Kale M; Zurek, Ludek

2012-02-15

To determine the prevalence of bacterial contamination on 4 surfaces of 4 types of standard equipment in small animal veterinary hospitals. Surveillance study. 10 small animal veterinary hospitals. Each hospital was visited 3 times at 4-month intervals; at each visit, a cage door, stethoscope, rectal thermometer, and mouth gag were swabbed. Swab samples were each plated onto media for culture of enterococci and organisms in the family Enterobacteriaceae. Enterococci were identified via a species-specific PCR assay and sodA gene sequencing; species of Enterobacteriaceae were identified with a biochemical test kit. Antimicrobial susceptibility was assessed via the disk diffusion method. Enterococci were screened for virulence traits and genotyped to assess clonality. Among the 10 hospitals, enterococci were isolated from cage doors in 7, from stethoscopes in 7, from thermometers in 6, and from mouth gags in 1; contamination with species of Enterobacteriaceae was rare. Enterococci were mainly represented by Enterococcus faecium (35.4%), Enterococcus faecalis (33.2%), and Enterococcus hirae (28.3%). Antimicrobial resistance was common in E. faecium, whereas virulence traits were present in 99% of E. faecalis isolates but not in E. faecium isolates. Clonal multidrug-resistant E. faecium was isolated from several surfaces at 1 hospital over multiple visits, whereas sporadic nonclonal contamination was detected in other hospitals. Contamination of surfaces in small animal veterinary hospitals with multidrug-resistant enterococci is a potential concern for pets and humans contacting these surfaces. Implementing precautions to minimize enterococcal contamination on these surfaces is recommended.
Efficacy of electrical resistivity and induced polarization methods for revealing fluoride contaminated groundwater in granite terrain.

PubMed

Mondal, Nepal C; Rao, Ananda V; Singh, Vijay P

2010-09-01

The accumulation of fluoride (F) in groundwater is a common phenomenon in India and worldwide. Its location can be identified through a direct hydrochemical analysis, which was carried out in Kurmapalli watershed (located 60 km SE of Hyderabad city), Nalgonda district, Andhra Pradesh, India affected by F contamination. The results of the hydrochemical analysis showed that F varied from 0.71 to 19.01 mg/l and its concentration exceeded the permissible limit (i.e., 1.5 mg/l) in 78% of the total 32 samples analyzed. The highest F value (19.01 mg/l) was found near Madnapur village, which is located in the central part of the watershed. Resistivity and induced polarization (IP) surveys were also carried out to reveal the zones where elevated F-contaminated groundwater exists. The objective of this paper was to highlight the utility of resistivity and IP surveys, using hydrochemical constituents as constraint, for the successful delineation of such contaminated/polluted groundwater zones in the granite area.
Brevibacillus sp. KUMAs2, a bacterial isolate for possible bioremediation of arsenic in rhizosphere.

PubMed

Mallick, Ivy; Hossain, Sk Tofajjen; Sinha, Sangram; Mukherjee, Samir Kumar

2014-09-01

Arsenic (As) contamination of soil and water has been considered as a major global environmental issue during last few decades. Among the various methods so far reported for reclamation of As contaminated rhizosphere soil, bioremediation using bacteria has been found to be most promising. An As resistant bacterial isolate Brevibacillus sp. KUMAs2 was obtained from As contaminated soil of Nadia, West Bengal, India, which could resist As(V) and As(III) a maximum of 265mM and 17mM, respectively. The strain could remove ~40 percent As under aerobic culture conditions. As resistant property in KUMAs2 was found to be plasmid-borne, which carried both As oxidizing and reducing genes. The strain could promote chilli plant growth under As contaminated soil environment by decreasing As accumulation in plant upon successful colonization in the rhizosphere, which suggests the possibility of using this isolate for successful bioremediation of As in the crop field. Copyright © 2014 Elsevier Inc. All rights reserved.
Study of Pyrex and quartz insulators contamination effect on the X-ray intensity in a 4-kJ plasma focus device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habibi, M., E-mail: mortezahabibi@aut.ac.ir; Sharifi, R.; Amrollahi, R.

2013-12-15

The variation of the X-ray intensity has been investigated with the Pyrex and quartz insulators surface contamination in a 4-kJ plasma focus device with argon gas at 11.5-kV charging voltage. Elemental analysis (EDAX) showed that the Cu evaporated from the electrode material and was deposited on the sleeve surface improves the breakdown conditions. A small level of sleeve contamination by copper is found to be essential for good focusing action and high HXR intensity. The SEM imaging showed the grain-type structure of Cu formed on the surface and it changed the surface property. Resistance measurements of original and coated Pyrexmore » surface proved that the copper deposition on the sleeve surface will reduce its resistance as compared to the almost infinitely large resistance of the uncontaminated sleeve. As the contamination is surpassed to some critical level, the HXR intensity from the device is deteriorated.« less
Geophysical Signitures From Hydrocarbon Contaminated Aquifers

NASA Astrophysics Data System (ADS)

Abbas, M.; Jardani, A.

2015-12-01

The task of delineating the contamination plumes as well as studying their impact on the soil and groundwater biogeochemical properties is needed to support the remediation efforts and plans. Geophysical methods including electrical resistivity tomography (ERT), induced polarization (IP), ground penetrating radar (GPR), and self-potential (SP) have been previously used to characterize contaminant plumes and investigate their impact on soil and groundwater properties (Atekwana et al., 2002, 2004; Benson et al., 1997; Campbell et al., 1996; Cassidy et al., 2001; Revil et al., 2003; Werkema et al., 2000). Our objective was to: estimate the hydrocarbon contamination extent in a contaminated site in northern France, and to adverse the effects of the oil spill on the groundwater properties. We aim to find a good combination of non-intrusive and low cost methods which we can use to follow the bio-remediation process, which is planned to proceed next year. We used four geophysical methods including electrical resistivity tomography, IP, GPR, and SP. The geophysical data was compared to geochemical ones obtained from 30 boreholes installed in the site during the geophysical surveys. Our results have shown: low electrical resistivity values; high chargeability values; negative SP anomalies; and attenuated GPR reflections coincident with groundwater contamination. Laboratory and field geochemical measurements have demonstrated increased groundwater electrical conductivity and increased microbial activity associated with hydrocarbon contamination of groundwater. Our study results support the conductive model suggested by studies such as Sauck (2000) and Atekwana et al., (2004), who suggest that biological alterations of hydrocarbon contamination can substantially modify the chemical and physical properties of the subsurface, producing a dramatic shift in the geo-electrical signature from resistive to conductive. The next stage of the research will include time lapse borehole and 3D geophysical measurements coupled to biological and chemical surface phase experiments in order to monitor the bioremediation processes.
Electrical Resistivity Tomography Monitoring of Soil Remediation for a Garbage Dump

NASA Astrophysics Data System (ADS)

shi, X.; Luo, Z.; Zhang, Y.; Fu, Q.; Xu, Z.

2011-12-01

Electrical resistivity tomography (ERT) survey was firstly used to investigate the distribution of contaminated soil in a garbage dump area, Wuhan city, China. The result shows that sulfated soil resistivity is about 4 to 7 ohm-m, which is relatively lower than normal soil resistivity of about 15 to 25 ohm-m. The distribution of contaminated soil was delineated using ERT images. Then, ERT survey was carried out in this area for monitoring of remediation of contaminated soil and groundwater. Werner measurements with 60 electrodes of 1 m spacing were taken during the 9-well oxygen injection and nutrition liquid injection period. The difference of apparent resistivity between before gas injection and after gas injection was used to delineate the channel of gas and the trace of gas migration in the porous garbage dump. The electrical resitivity changes between before and after nutrition liquid injection were used to analyze the liquid migration and distribution. The dynamic procedures of gas and water migration are outlined. The results suggest that ERT is a powerful technique for monitoring of soil remediation.
Impairment of O-antigen production confers resistance to grazing in a model amoeba-cyanobacterium predator-prey system.

PubMed

Simkovsky, Ryan; Daniels, Emy F; Tang, Karen; Huynh, Stacey C; Golden, Susan S; Brahamsha, Bianca

2012-10-09

The grazing activity of predators on photosynthetic organisms is a major mechanism of mortality and population restructuring in natural environments. Grazing is also one of the primary difficulties in growing cyanobacteria and other microalgae in large, open ponds for the production of biofuels, as contaminants destroy valuable biomass and prevent stable, continuous production of biofuel crops. To address this problem, we have isolated a heterolobosean amoeba, HGG1, that grazes upon unicellular and filamentous freshwater cyanobacterial species. We have established a model predator-prey system using this amoeba and Synechococcus elongatus PCC 7942. Application of amoebae to a library of mutants of S. elongatus led to the identification of a grazer-resistant knockout mutant of the wzm ABC O-antigen transporter gene, SynPCC7942_1126. Mutations in three other genes involved in O-antigen synthesis and transport also prevented the expression of O-antigen and conferred resistance to HGG1. Complementation of these rough mutants returned O-antigen expression and susceptibility to amoebae. Rough mutants are easily identifiable by appearance, are capable of autoflocculation, and do not display growth defects under standard laboratory growth conditions, all of which are desired traits for a biofuel production strain. Thus, preventing the production of O-antigen is a pathway for producing resistance to grazing by certain amoebae.
Metabolic engineering of plant-derived (E)-β-farnesene synthase genes for a novel type of aphid-resistant genetically modified crop plants.

PubMed

Yu, Xiu-Dao; Pickett, John; Ma, You-Zhi; Bruce, Toby; Napier, Johnathan; Jones, Huw D; Xia, Lan-Qin

2012-05-01

Aphids are major agricultural pests that cause significant yield losses of crop plants each year. Excessive dependence on insecticides for long-term aphid control is undesirable because of the development of insecticide resistance, the potential negative effects on non-target organisms and environmental pollution. Transgenic crops engineered for resistance to aphids via a non-toxic mode of action could be an efficient alternative strategy. (E)-β-Farnesene (EβF) synthases catalyze the formation of EβF, which for many pest aphids is the main component of the alarm pheromone involved in the chemical communication within these species. EβF can also be synthesized by certain plants but is then normally contaminated with inhibitory compounds. Engineering of crop plants capable of synthesizing and emitting EβF could cause repulsion of aphids and also the attraction of natural enemies that use EβF as a foraging cue, thus minimizing aphid infestation. In this review, the effects of aphids on host plants, plants' defenses against aphid herbivory and the recruitment of natural enemies for aphid control in an agricultural setting are briefly introduced. Furthermore, the plant-derived EβF synthase genes cloned to date along with their potential roles in generating novel aphid resistance via genetically modified approaches are discussed. © 2012 Institute of Botany, Chinese Academy of Sciences.
Impairment of O-antigen production confers resistance to grazing in a model amoeba–cyanobacterium predator–prey system

PubMed Central

Simkovsky, Ryan; Daniels, Emy F.; Tang, Karen; Huynh, Stacey C.; Golden, Susan S.; Brahamsha, Bianca

2012-01-01

The grazing activity of predators on photosynthetic organisms is a major mechanism of mortality and population restructuring in natural environments. Grazing is also one of the primary difficulties in growing cyanobacteria and other microalgae in large, open ponds for the production of biofuels, as contaminants destroy valuable biomass and prevent stable, continuous production of biofuel crops. To address this problem, we have isolated a heterolobosean amoeba, HGG1, that grazes upon unicellular and filamentous freshwater cyanobacterial species. We have established a model predator–prey system using this amoeba and Synechococcus elongatus PCC 7942. Application of amoebae to a library of mutants of S. elongatus led to the identification of a grazer-resistant knockout mutant of the wzm ABC O-antigen transporter gene, SynPCC7942_1126. Mutations in three other genes involved in O-antigen synthesis and transport also prevented the expression of O-antigen and conferred resistance to HGG1. Complementation of these rough mutants returned O-antigen expression and susceptibility to amoebae. Rough mutants are easily identifiable by appearance, are capable of autoflocculation, and do not display growth defects under standard laboratory growth conditions, all of which are desired traits for a biofuel production strain. Thus, preventing the production of O-antigen is a pathway for producing resistance to grazing by certain amoebae. PMID:23012457
Environmental protection of titanium alloys at high temperatures

NASA Technical Reports Server (NTRS)

Wright, I. G.; Wood, R. A.; Seltzer, M. S.

1974-01-01

Various concepts were evaluated for protecting titanium alloys from oxygen contamination at 922 K (1200 F) and from hot-salt stress-corrosion at 755 K (900 F). It is indicated that oxygen-contamination resistance can be provided by a number of systems, but for hot-salt stress-corrosion resistance, factors such as coating integrity become very important. Titanium aluminides resist oxygen ingress at 922 K through the formation of alumina (on TiAl3) or modified TiO2 (on Ti3Al, TiAl) scales. TiAl has some resistance to attack by hot salt, but has limited ductility. Ductile Ti-Ni and Ti-Nb-Cr-Al alloys provide limited resistance to oxygen ingress, but are not greatly susceptible to hot-salt stress-corrosion cracking.
Effects of pesticides and contaminants on neotropical migrants

Treesearch

Nicholas W. Gard; Michael J. Hooper; Richard S. Bennett

1993-01-01

Many agricultural pesticides and industrial contaminants are capable of adversely affecting birds through direct effects such as elevated mortality rates and decreased reproductive success or indirectly by modifying habitat composition or food availability. Although neotropical migrants are potentially exposed to these contaminants on their breeding, migratory and...
Emerging contaminants and nutrients synergistically affect the spread of class 1 integron-integrase (intI1) and sul1 genes within stable streambed bacterial communities.

PubMed

Subirats, Jèssica; Timoner, Xisca; Sànchez-Melsió, Alexandre; Balcázar, José Luis; Acuña, Vicenç; Sabater, Sergi; Borrego, Carles M

2018-07-01

Wastewater effluents increase the nutrient load of receiving streams while introducing a myriad of anthropogenic chemical pollutants that challenge the resident aquatic (micro)biota. Disentangling the effects of both kind of stressors and their potential interaction on the dissemination of antibiotic resistance genes in bacterial communities requires highly controlled manipulative experiments. In this work, we investigated the effects of a combined regime of nutrients (at low, medium and high concentrations) and a mixture of emerging contaminants (ciproﬂoxacin, erythromycin, sulfamethoxazole, diclofenac, and methylparaben) on the bacterial composition, abundance and antibiotic resistance profile of biofilms grown in artificial streams. In particular, we investigated the effect of this combined stress on genes encoding resistance to ciprofloxacin (qnrS), erythromycin (ermB), sulfamethoxazole (sul1 and sul2) as well as the class 1 integron-integrase gene (intI1). Only genes conferring resistance to sulfonamides (sul1 and sul2) and intI1 gene were detected in all treatments during the study period. Besides, bacterial communities exposed to emerging contaminants showed higher copy numbers of sul1 and intI1 genes than those not exposed, whereas nutrient amendments did not affect their abundance. However, bacterial communities exposed to both emerging contaminants and a high nutrient concentration (1, 25 and 1 mg L -1 of phosphate, nitrate and ammonium, respectively) showed the highest increase on the abundance of sul1 and intI1 genes thus suggesting a factors synergistic effect of both stressors. Since none of the treatments caused a significant change on the composition of bacterial communities, the enrichment of sul1 and intI1 genes within the community was caused by their dissemination under the combined pressure exerted by nutrients and emerging contaminants. To the best of our knowledge, this is the first study demonstrating the contribution of nutrients on the maintenance and spread of antibiotic resistance genes in streambed biofilms under controlled conditions. Our results also highlight that nutrients could enhance the effect of emerging contaminants on the dissemination of antibiotic resistance. Copyright © 2018 Elsevier Ltd. All rights reserved.
Co-occurrence of antibiotic drugs, resistant bacteria and resistance genes in runoff from cattle feedlots

USDA-ARS?s Scientific Manuscript database

Agricultural uses of antibiotics raises concerns about the development of antibiotic resistance in food animals, and the potential to transmit resistance to human clinical settings via fecal contamination of surface and ground water. Although there is broad agreement that agricultural resistance can...
Detection, Occurrence and Fate of Emerging Contaminants in Agricultural Environments

PubMed Central

Cassada, David A.; Bartelt–Hunt, Shannon L.; Li, Xu; D’Alessio, Matteo; Zhang, Yun; Zhang, Yuping; Sallach, J. Brett

2018-01-01

A total of 59 papers published in 2015 were reviewed ranging from detailed descriptions of analytical methods, to fate and occurrence studies, to ecological effects and sampling techniques for a wide variety of emerging contaminants likely to occur in agricultural environments. New methods and studies on veterinary pharmaceuticals, steroids, antibiotic resistance genes in agricultural environments continue to expand our knowledge base on the occurrence and potential impacts of these compounds. This review is divided into the following sections: Introduction, Analytical Methods, Steroid Hormones, Pharmaceutical Contaminants, Transformation Products, and “Antibiotic Resistance, Drugs, Bugs and Genes”. PMID:27620078
Distribution of triclosan-resistant genes in major pathogenic microorganisms revealed by metagenome and genome-wide analysis

PubMed Central

Khan, Raees; Roy, Nazish; Choi, Kihyuck

2018-01-01

The substantial use of triclosan (TCS) has been aimed to kill pathogenic bacteria, but TCS resistance seems to be prevalent in microbial species and limited knowledge exists about TCS resistance determinants in a majority of pathogenic bacteria. We aimed to evaluate the distribution of TCS resistance determinants in major pathogenic bacteria (N = 231) and to assess the enrichment of potentially pathogenic genera in TCS contaminated environments. A TCS-resistant gene (TRG) database was constructed and experimentally validated to predict TCS resistance in major pathogenic bacteria. Genome-wide in silico analysis was performed to define the distribution of TCS-resistant determinants in major pathogens. Microbiome analysis of TCS contaminated soil samples was also performed to investigate the abundance of TCS-resistant pathogens. We experimentally confirmed that TCS resistance could be accurately predicted using genome-wide in silico analysis against TRG database. Predicted TCS resistant phenotypes were observed in all of the tested bacterial strains (N = 17), and heterologous expression of selected TCS resistant genes from those strains conferred expected levels of TCS resistance in an alternative host Escherichia coli. Moreover, genome-wide analysis revealed that potential TCS resistance determinants were abundant among the majority of human-associated pathogens (79%) and soil-borne plant pathogenic bacteria (98%). These included a variety of enoyl-acyl carrier protein reductase (ENRs) homologues, AcrB efflux pumps, and ENR substitutions. FabI ENR, which is the only known effective target for TCS, was either co-localized with other TCS resistance determinants or had TCS resistance-associated substitutions. Furthermore, microbiome analysis revealed that pathogenic genera with intrinsic TCS-resistant determinants exist in TCS contaminated environments. We conclude that TCS may not be as effective against the majority of bacterial pathogens as previously presumed. Further, the excessive use of this biocide in natural environments may selectively enrich for not only TCS-resistant bacterial pathogens, but possibly for additional resistance to multiple antibiotics. PMID:29420585
Sterilization of medical equipment and contaminated articles by making use of a resistive barrier discharge

NASA Astrophysics Data System (ADS)

Uhm, Han S.; Kang, Jung G.; Choi, Eun H.; Cho, Guang S.

2012-08-01

Presented here is an apparatus consisting of an atmospheric resistive-barrier discharge for the sterilization of medical tools wrapped in typical hospital cloths, for the sterilization of manufactured drugs in typical packaging materials, and for the sterilization of biologically-contaminated articles. The sterilization apparatus consists of layers of the resistive-barrier discharge device operating at room temperature, a sterilization chamber, and an ozone destruction device. An electrical discharge in the resistive-barrier discharge system generates an atmospheric plasma in oxygen gas, generating ozone, which in turn efficiently sterilizes medical tools and biologically contaminated articles at room temperature. A sterilization experiment was carried out at an apparatus volume of 100 liters, with a sterilization chamber volume of 60 liters, and a discharge device volume of 40 liters. The sterilization in this experiment required 60 W of power for 5 hours of residence time. For a given sterilization time, the required electrical power was proportional to the apparatus volume. Ozone in the sterilization chamber was destroyed safely after sterilization.

Occurrence and antimicrobial resistance patterns of Listeria monocytogenes isolated from vegetables.

PubMed

de Vasconcelos Byrne, Vanessa; Hofer, Ernesto; Vallim, Deyse Christina; de Castro Almeida, Rogeria Comastri

2016-01-01

Although the consumption of fresh and minimally processed vegetables is considered healthy, outbreaks related to the contamination of these products are frequently reported. Among the food-borne pathogens that contaminate vegetables is Listeria monocytogenes, a ubiquitous organism that exhibits the ability to survive and multiply at refrigerated temperatures. This study aimed to evaluate the occurrence of L. monocytogenes in vegetables as well as the antimicrobial resistance of isolates. The results showed that 3.03% of samples were contaminated with L. monocytogenes, comprising 2.22% of raw vegetables and 5.56% of ready-to-eat vegetables. Multiplex PCR confirmed the virulence potential of the isolates. Antimicrobial resistance profiling showed that 50% of the isolates were susceptible to the antibiotics used. The resistance of one isolate to penicillin G, a commonly employed therapeutic agent, and the presence of serotype 4b, a serotype commonly associated with food-borne outbreaks, could be potential health hazards for consumers. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.
The update of resist outgas testing for metal containing resists at EIDEC

NASA Astrophysics Data System (ADS)

Shiobara, Eishi; Mikami, Shinji

2017-10-01

The metal containing resist is one of the candidates for high sensitivity resists. EIDEC has prepared the infrastructure for outgas testing in hydrogen environment for metal containing resists at High Power EUV irradiation tool (HPEUV). We have experimentally obtained the preliminary results of the non-cleanable metal contamination on witness sample using model material by HPEUV [1]. The metal contamination was observed at only the condition of hydrogen environment. It suggested the generation of volatile metal hydrides by hydrogen radicals. Additionally, the metal contamination on a witness sample covered with Ru was not removed by hydrogen radical cleaning. The strong interaction between the metal hydride and Ru was confirmed by the absorption simulation. Recently, ASML announced a resist outgassing barrier technology using Dynamic Gas Lock (DGL) membrane located between projection optics and wafer stage [2], [3]. DGL membrane blocks the diffusion of all kinds of resist outgassing to the projection optics and prevents the reflectivity loss of EUV mirrors. The investigation of DGL membrane for high volume manufacturing is just going on. It extends the limitation of material design for EUV resists. However, the DGL membrane has an impact for the productivity of EUV scanners due to the transmission loss of EUV light and the necessity of periodic maintenance. The well understanding and control of the outgassing characteristics of metal containing resists may help to improve the productivity of EUV scanner. We consider the outgas evaluation for the resists still useful. For the improvement of resist outgas testing by HPEUV, there are some issues such as the contamination limited regime, the optimization of exposure dose to obtain the measurable contamination film thickness and the detection of minimum amount of metal related outgas species generated. The investigation and improvement for these issues are ongoing. The updates will be presented in the conference. This work was supported by Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO). [1] Eishi Shiobara, Shinji Mikami, Satoshi Tanaka, International Symposium on EUV Lithography, Hiroshima, Japan, P-RE-01, (2016). [2] Mark van de Kerkhof, Hans Jasper, Leon Levasier, Rudy Peeters, Roderik van Es, Jan-Willem Bosker, Alexander Zdravkov, Egbert Lenderink, Fabrizio Evangelista, Par Broman, Bartosz Bilski, Thorsten Last, Proc. of SPIE Vol. 10143, 101430D (2017). [3] Oktay Yildirim, Elizabeth Buitrago, Rik Hoefnagels, Marieke Meeuwissen, Sander Wuister, Gijsbert Rispens, Anton van Oosten, Paul Derks, Jo Finders, Michaela Vockenhuber, Yasin Ekinci, Proc. of SPIE Vol. 10143, 101430Q (2017).
Next-generation sequencing (NGS) for assessment of microbial water quality: current progress, challenges, and future opportunities

PubMed Central

Tan, BoonFei; Ng, Charmaine; Nshimyimana, Jean Pierre; Loh, Lay Leng; Gin, Karina Y.-H.; Thompson, Janelle R.

2015-01-01

Water quality is an emergent property of a complex system comprised of interacting microbial populations and introduced microbial and chemical contaminants. Studies leveraging next-generation sequencing (NGS) technologies are providing new insights into the ecology of microbially mediated processes that influence fresh water quality such as algal blooms, contaminant biodegradation, and pathogen dissemination. In addition, sequencing methods targeting small subunit (SSU) rRNA hypervariable regions have allowed identification of signature microbial species that serve as bioindicators for sewage contamination in these environments. Beyond amplicon sequencing, metagenomic and metatranscriptomic analyses of microbial communities in fresh water environments reveal the genetic capabilities and interplay of waterborne microorganisms, shedding light on the mechanisms for production and biodegradation of toxins and other contaminants. This review discusses the challenges and benefits of applying NGS-based methods to water quality research and assessment. We will consider the suitability and biases inherent in the application of NGS as a screening tool for assessment of biological risks and discuss the potential and limitations for direct quantitative interpretation of NGS data. Secondly, we will examine case studies from recent literature where NGS based methods have been applied to topics in water quality assessment, including development of bioindicators for sewage pollution and microbial source tracking, characterizing the distribution of toxin and antibiotic resistance genes in water samples, and investigating mechanisms of biodegradation of harmful pollutants that threaten water quality. Finally, we provide a short review of emerging NGS platforms and their potential applications to the next generation of water quality assessment tools. PMID:26441948
Functional gene array-based analysis of microbial community structure in groundwaters with a gradient of contaminant levels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waldron, P.J.; Wu, L.; Van Nostrand, J.D.

2009-06-15

To understand how contaminants affect microbial community diversity, heterogeneity, and functional structure, six groundwater monitoring wells from the Field Research Center of the U.S. Department of Energy Environmental Remediation Science Program (ERSP; Oak Ridge, TN), with a wide range of pH, nitrate, and heavy metal contamination were investigated. DNA from the groundwater community was analyzed with a functional gene array containing 2006 probes to detect genes involved in metal resistance, sulfate reduction, organic contaminant degradation, and carbon and nitrogen cycling. Microbial diversity decreased in relation to the contamination levels of the wells. Highly contaminated wells had lower gene diversity butmore » 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.« less
Evaluation of surface water and groundwater contamination in a MSW landfill area using hydrochemical analysis and electrical resistivity tomography: a case study in Sichuan province, Southwest China.

PubMed

Ling, Chengpeng; Zhang, Qiang

2017-04-01

As a primary disposal mean of municipal solid waste in China, the landfill has been recognized as one of the major threats to the surrounding surface water and groundwater environment due to the emission of leachate. The aim of this study was to determine the impact of leachate on the surface water and groundwater environment of the region of the Chang'an landfill, which is located in Sichuan province, China. The surface water and groundwater were sampled for hydrochemical analysis. Three electrical resistivity tomography profiles were conducted to evaluate the impact of leachate on the groundwater environment, and several laboratory tests were carried out to build the relationship between the soil bulk resistivity and the void fluid resistivity. The results showed that a seasonal creek named Longfeng creek, which crosses the landfill site, was contaminated by the leachate. The concentrations of COD, BOD5, and chlorides (Cl) of surface water samples increased by 12.3-105.7 times. The groundwater quality in the surface loose sediments along the valley deteriorated obviously from the landfill to 500 m downstream area. The laboratory tests of soil samples indicated that the resistivity value of 13 Ωm is a critical value whether the groundwater in the loose sediments is polluted. The groundwater at the site adjacent to the spillway in the landfill was partially contaminated by the emission of leachate. The groundwater contamination zones at 580 m downstream of the landfill were recognized at the shallow zones from 60 m left bank to 30 m right bank of Longfeng creek. The improved understanding of groundwater contamination around the landfill is beneficial for the landfill operation and groundwater environment remediation.
The value of DCIP geophysical surveys for contaminated site investigations

NASA Astrophysics Data System (ADS)

Balbarini, N.; Rønde, V.; Maurya, P. K.; Møller, I.; McKnight, U. S.; Christiansen, A. V.; Binning, P. J.; Bjerg, P. L.

2017-12-01

Geophysical methods are increasingly being used in contaminant hydrogeology to map lithology, hydraulic properties, and contaminant plumes with a high ionic strength. Advances in the Direct Current resistivity and Induced Polarization (DCIP) method allow the collection of high resolution three dimensional (3D) data sets. The DC resistivity can describe both soil properties and the water electrical conductivity, while the IP can describe the lithology and give information on hydrogeological properties. The aim of the study was to investigate a large contaminant plume discharging to a stream from an old factory site by combining traditional geological, hydrological, and contaminant concentration data with DCIP surveys. The plume consisted of xenobiotic organic compounds and inorganics. The study assesses benefits and limitations of DCIP geophysics for contaminated site investigations. A 3D geological model was developed from borehole logs and DCIP data as framework for the complex transport pathways near the meandering stream. IP data were useful in indicating the continuity and the changes in thickness of local clay layers between the borehole logs. The geological model was employed to develop a groundwater flow model describing groundwater flows to the stream. The hydraulic conductivity distribution was based on IP data, slug tests and grain size analysis. The distribution of contaminant concentrations revealed two chemically distinct plumes, separated by a clay layer, with different transport paths to the stream. The DC resistivity was useful in mapping ionic compounds, but also organic compounds whose spatial distribution coincided with the ionic compounds. A conceptual model describing the contaminant plume was developed, and it matched well with contaminant concentrations in stream water and below the streambed. Surface DCIP surveys supported the characterization of the spatial variability in geology, hydraulic conductivity and contaminant concentration. Though DCIP data interpretation required additional borehole data, the DCIP survey reduced the number of boreholes required and helped design field campaigns. The results suggest DCIP surveys are useful and inexpensive tools, which has potential as an integrated part of contaminated site investigations.
Antimicrobial peptides against contaminating bacteria in fuel ethanol production

USDA-ARS?s Scientific Manuscript database

Lactic acid bacteria (LAB) are commonly found as contaminants of fuel ethanol production, resulting in reduced ethanol yields: (1). Recent reports suggest that LAB can develop resistance to antibiotics such as virginiamycin and penicillin that are commonly used to control bacterial contamination; (2...
Antimicrobial peptides against contaminating bacteria in fuel ethanol production

USDA-ARS?s Scientific Manuscript database

Lactic acid bacteria (LAB) are commonly found as contaminants of fuel ethanol production, resulting in reduced ethanol yields (1). Recent reports suggest that LAB can develop resistance to antibiotics such as virginiamycin and penicillin that are commonly used to control bacterial contamination (2)...
[Bile-resistant Gram-negative bacteria effect of different kinds of root decoction pieces].

PubMed

Deng, Yan; Wang, Ya-Ke; Han, Xiao-Yu; Wang, Ya-Qi; Jiang, Zhen-Yu; Yu, Zhi-Jun; Deng, Hai-Ying

2017-11-01

To investigate the microbial contamination in Chinese herbal decoction pieces with different functional types by studying the total aerobic microbial count (TAMC), and total yeast and mould count (TYMC) in 40 samples of 8 types of root decoction pieces; further evaluate the contamination load of bile-resistant Gram-negative bacteria, and identify the Gram-negative bacteria by using biochemical identification system for Gram-negative bacteria. Our results showed that the TAMC value was more than 1 000 CFU•g⁻¹ in 85% (34/40) samples, and was more than 100 CFU•g⁻¹ in 30% (12/40) samples; the contamination of bile-resistant Gram-negative bacteria was detected in 45% (18/40) of the samples. The bile-resistant Gram-negative bacteria load of seven batches of samples was N>1 000 MPN•g⁻¹. Sixteen bacterium strains including Serratia plymouthensis, Cedecea neteri, Escherichia vulneris, Klebsiella oxytoca, Enterobacter amnigenus, E. cloacae, E. sakazakii, Proteus penneri and E. gergoviae were obtained and identified. E. cloacae was the predominant bacterium that was isolated from Salviae Miltiorrhizae Radix et Rhizoma, while E. amnigenus, Yersinia pseudotuberculosis was the typical bacterium of Ophiopogonis Radix and Codonopsis Radix, respectively. All these suggested that the contamination of bile-resistant Gram-negative bacteria was severe for the root decoction pieces in Wuhan city. Microbial species have certain selection specificity for medicinal ingredients, so the type and limit of control bacteria for detection should be formulated according to the pollution type and quantity of bile-resistant Gram-negative bacteria. Copyright© by the Chinese Pharmaceutical Association.
Label-Free Biosensing with High Selectivity in Complex Media using Microtoroidal Optical Resonators

NASA Astrophysics Data System (ADS)

Ozgur, Erol; Toren, Pelin; Aktas, Ozan; Huseyinoglu, Ersin; Bayindir, Mehmet

2015-08-01

Although label-free biosensors comprised of optical microcavities inherently possess the capability of resolving molecular interactions at individual level, this extreme sensitivity restricts their convenience for large scale applications by inducing vulnerability towards non-specific interactions that readily occur within complex media. Therefore, the use of optical microresonators for biosensing is mostly limited within strictly defined laboratory conditions, instead of field applications as early detection of cancer markers in blood, or identification of contamination in food. Here, we propose a novel surface modification strategy suitable for but not limited to optical microresonator based biosensors, enabling highly selective biosensing with considerable sensitivity as well. Using a robust, silane-based surface coating which is simultaneously protein resistant and bioconjugable, we demonstrate that it becomes possible to perform biosensing within complex media, without compromising the sensitivity or reliability of the measurement. Functionalized microtoroids are successfully shown to resist nonspecific interactions, while simultaneously being used as sensitive biological sensors. This strategy could pave the way for important applications in terms of extending the use of state-of-the-art biosensors for solving problems similar to the aforementioned.
Antibiotic resistance of microorganisms in agricultural soils in Russia

NASA Astrophysics Data System (ADS)

Danilova, Natasha; Galitskaya, Polina; Selivanovskaya, Svetlana

2017-04-01

Antibiotics are medicines widely used to treat and prevent bacterial infections not only in human medicine but also in veterinary. Besides, in animal husbandry antibiotics are often used in for stimulation of animal's growth. Many antibiotics used for veterinary purposes are weakly absorbed in the animal's gut. So up to 90% of the administered antibiotics are excreted with manure and urine. Therefore use of manure as an organic fertilizer leads to formation and spreading of antibiotic resistance among soil microbes. Another reason of such spreading is the horizontal transfer of genes encoding antibiotic resistance from manure to soil microflora. The level of antibiotic resistance genes pollution of soils has not been properly studied yet. The aim of this study was to estimate the contamination of agricultural soils by antibiotic resistant genes. 30 samples of agricultural soils were selected around of Kazan city (Tatarstan Republic) with 1.3 Mio citizens. Since tetracycline is reported to be the most wide spread veterinary antibiotic in Russia, we estimated the level of soil contamination by tet(X) gene encoding tetracycline decomposition in microbial cell. Real time PCR method with specific primers was used as a method of investigation. Particle size type distribution of 31% of soil samples was estimated to be sandy clay, and 69% of soil samples - to silty clay. Content of dissoluble organic carbon ranged from 0,02 mg g -1 (sample 20) to 0,46 mg g -1 (sample 16). Respiration activity and microbial biomass of soils were estimated to be 0,80-5,28 CO2 C mg g -1 h-1 and 263,51-935,77 µg kg - 1 respectively. The values presented are typical for soils of Tatarstan Republic. In terms of the antibiotic resistant gene content, 27 of 30 samples investigated contained tet(X) gene, while 52% of the samples were highly contaminated, 34% of samples were middle contaminated and 14% of samples - weakly contaminated.
Stress tolerant virulent strains of Cronobacter sakazakii from food.

PubMed

Fakruddin, Md; Rahaman, Mizanur; Ahmed, Monzur Morshed; Hoque, Md Mahfuzul

2014-11-25

Cronobacter sakazakii is considered as an emerging foodborne pathogen. The aim of this study was to isolate and characterize virulent strains of Cronobacter sakazakii from food samples of Bangladesh. Six (6) Cronobacter sakazakii was isolated and identified from 54 food samples on the basis of biochemical characteristics, sugar fermentation, SDS-PAGE of whole cell protein, plasmid profile and PCR of Cronobacter spp. specific genes (esak, gluA, zpx, ompA, ERIC, BOX-AIR) and sequencing. These strains were found to have moderately high antibiotic resistance against common antibiotics and some are ESBL producer. Most of the C. sakazakii isolates were capable of producing biofilm (strong biofilm producer), extracellular protease and siderophores, curli expression, haemolysin, haemagglutinin, mannose resistant haemagglutinin, had high cell surface hydrophobicity, significant resistance to human serum, can tolerate high concentration of salt, bile and DNase production. Most of them produced enterotoxins of different molecular weight. The isolates pose significant serological cross-reactivity with other gram negative pathogens such as serotypes of Salmonella spp., Shigella boydii, Shigella sonnei, Shigella flexneri and Vibrio cholerae. They had significant tolerance to high temperature, low pH, dryness and osmotic stress. Special attention should be given in ensuring hygiene in production and post-processing to prevent contamination of food with such stress-tolerant virulent Cronobacter sakazakii.
The role of drinking water in the transmission of antimicrobial-resistant E. coli.

PubMed

Coleman, B L; Salvadori, M I; McGeer, A J; Sibley, K A; Neumann, N F; Bondy, S J; Gutmanis, I A; McEwen, S A; Lavoie, M; Strong, D; Johnson, I; Jamieson, F B; Louie, M

2012-04-01

To determine whether drinking water contaminated with antimicrobial-resistant E. coli is associated with the carriage of resistant E. coli, selected households sending water samples to Ontario and Alberta laboratories in 2005-2006 were asked to participate in a cross-sectional study. Household members aged ≥12 years were asked to complete a questionnaire and to submit a rectal swab. In 878 individuals, 41% carried a resistant strain of E. coli and 28% carried a multidrug-resistant strain. The risk of carriage of resistant E. coli was 1·26 times higher for users of water contaminated with resistant E. coli. Other risk factors included international travel [prevalence ratio (PR) 1·33], having a child in nappies (PR 1·33), being male (PR 1·33), and frequent handling of raw red meats (PR 1·10). Protecting private water sources (e.g. by improving systems to test and treat them) may help slow the emergence of antimicrobial resistance in E. coli.
Presence, Distribution, and Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in a Small Animal Teaching Hospital: A Year-Long Active Surveillance Targeting Dogs and Their Environment

PubMed Central

van Balen, Joany; Kelley, Christina; Nava-Hoet, Rocio C.; Bateman, Shane; Hillier, Andrew; Dyce, Jonathan; Wittum, Thomas E.

2013-01-01

Abstract Methicillin-resistant Staphylococcus aureus (MRSA) is known to be present in small animal veterinary clinical environments. However, a better understanding of the ecology and dynamics of MRSA in these environments is necessary for the development of effective infectious disease prevention and control programs. To achieve this goal, a yearlong active MRSA surveillance program was established at The Ohio State University (OSU) Veterinary Medical Center to describe the spatial and molecular epidemiology of this bacterium in the small animal hospital. Antimicrobial susceptibility testing, staphylococcal chromosomal cassette mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE) typing, and dendrogram analysis were used to characterize and analyze the 81 environmental and 37 canine-origin MRSA isolates obtained during monthly sampling events. Overall, 13.5% of surfaces were contaminated with MRSA at 1 or more sampling times throughout the year. The majority of the environmental and canine isolates were SCCmec type II (93.8% and 86.5%, respectively) and USA100 (90.1% and 86.5%, respectively). By PFGE analysis, these isolates were found to be closely related, which reflects a low diversity of MRSA strains circulating in the hospital. For 5 consecutive months, 1 unique pulsotype was the most prevalent across the medical services and was recovered from a variety of surfaces and hospital locations. Carts/gurneys, doors, and examination tables/floors were the most frequently contaminated surfaces. Some surfaces maintained the same pulsotypes for 3 consecutive months. Molecular analysis found that incoming MRSA-positive dogs were capable of introducing a new pulsotype into the hospital environment during the surveillance period. Our results suggest that once a MRSA strain is introduced into the hospital environment, it can be maintained and spread for extended periods of time. These findings can aid in the development of biosecurity and biocontainment protocols aimed at reducing environmental contamination and potential exposures to MRSA in veterinary hospital staff, clients, and patients. PMID:23473216
Presence, distribution, and molecular epidemiology of methicillin-resistant Staphylococcus aureus in a small animal teaching hospital: a year-long active surveillance targeting dogs and their environment.

PubMed

van Balen, Joany; Kelley, Christina; Nava-Hoet, Rocio C; Bateman, Shane; Hillier, Andrew; Dyce, Jonathan; Wittum, Thomas E; Hoet, Armando E

2013-05-01

Methicillin-resistant Staphylococcus aureus (MRSA) is known to be present in small animal veterinary clinical environments. However, a better understanding of the ecology and dynamics of MRSA in these environments is necessary for the development of effective infectious disease prevention and control programs. To achieve this goal, a yearlong active MRSA surveillance program was established at The Ohio State University (OSU) Veterinary Medical Center to describe the spatial and molecular epidemiology of this bacterium in the small animal hospital. Antimicrobial susceptibility testing, staphylococcal chromosomal cassette mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE) typing, and dendrogram analysis were used to characterize and analyze the 81 environmental and 37 canine-origin MRSA isolates obtained during monthly sampling events. Overall, 13.5% of surfaces were contaminated with MRSA at 1 or more sampling times throughout the year. The majority of the environmental and canine isolates were SCCmec type II (93.8% and 86.5%, respectively) and USA100 (90.1% and 86.5%, respectively). By PFGE analysis, these isolates were found to be closely related, which reflects a low diversity of MRSA strains circulating in the hospital. For 5 consecutive months, 1 unique pulsotype was the most prevalent across the medical services and was recovered from a variety of surfaces and hospital locations. Carts/gurneys, doors, and examination tables/floors were the most frequently contaminated surfaces. Some surfaces maintained the same pulsotypes for 3 consecutive months. Molecular analysis found that incoming MRSA-positive dogs were capable of introducing a new pulsotype into the hospital environment during the surveillance period. Our results suggest that once a MRSA strain is introduced into the hospital environment, it can be maintained and spread for extended periods of time. These findings can aid in the development of biosecurity and biocontainment protocols aimed at reducing environmental contamination and potential exposures to MRSA in veterinary hospital staff, clients, and patients.
Cross-sectional point prevalence survey to study the environmental contamination of nosocomial pathogens in intensive care units under real-life conditions.

PubMed

Wille, I; Mayr, A; Kreidl, P; Brühwasser, C; Hinterberger, G; Fritz, A; Posch, W; Fuchs, S; Obwegeser, A; Orth-Höller, D; Lass-Flörl, C

2018-01-01

In intensive care units (ICUs), inanimate surfaces and equipment may be contaminated by nosocomial pathogens, including multi-drug-resistant micro-organisms. To assess the degree of environmental contamination close to and distant from patients, and contamination of healthcare workers' (HCWs) hands with nosocomial pathogens under real-life conditions and to investigate potential transmission events. Over the course of three weeks, agar contact samples were taken close to and distant from patient areas and from HCWs' hands in eight ICUs of a tertiary care hospital in Innsbruck, Austria. Each ICU was visited once without announcement. Species identification and antimicrobial susceptibility testing were performed according to standard methods, and corresponding strains from patient, environment and hand samples were genotyped using pulsed-field gel electrophoresis. Among 523 samples, HCWs' hands were most frequently contaminated with potentially pathogenic bacteria (15.2%), followed by areas close to patients (10.9%) and areas distant from patients (9.1%). Gram-positive bacteria were identified most often (67.8%), with Enterococcus spp. being the most prevalent species (70% vancomycin sensitive and 30% vancomycin resistant) followed by Staphylococcus aureus, of which 64% were classified as meticillin-resistant Staphylococcus aureus. Molecular typing documented identical strains among patient, environment and hand isolates. This study found widespread contamination of the ICU environment with clinically relevant pathogens, including multi-drug-resistant micro-organisms, despite cleaning and disinfection. The bioburden might not be restricted to areas close to patients. The role of extended environmental disinfection of areas distant from patients in order to improve infection prevention needs further discussion. Copyright © 2017 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
Functional metagenomics reveals a novel carbapenem-hydrolyzing mobile beta-lactamase from Indian river sediments contaminated with antibiotic production waste.

PubMed

Marathe, Nachiket P; Janzon, Anders; Kotsakis, Stathis D; Flach, Carl-Fredrik; Razavi, Mohammad; Berglund, Fanny; Kristiansson, Erik; Larsson, D G Joakim

2018-03-01

Evolution has provided environmental bacteria with a plethora of genes that give resistance to antibiotic compounds. Under anthropogenic selection pressures, some of these genes are believed to be recruited over time into pathogens by horizontal gene transfer. River sediment polluted with fluoroquinolones and other drugs discharged from bulk drug production in India constitute an environment with unprecedented, long-term antibiotic selection pressures. It is therefore plausible that previously unknown resistance genes have evolved and/or are promoted here. In order to search for novel resistance genes, we therefore analyzed such river sediments by a functional metagenomics approach. DNA fragments providing resistance to different antibiotics in E. coli were sequenced using Sanger and PacBio RSII platforms. We recaptured the majority of known antibiotic resistance genes previously identified by open shot-gun metagenomics sequencing of the same samples. In addition, seven novel resistance gene candidates (six beta-lactamases and one amikacin resistance gene) were identified. Two class A beta-lactamases, bla RSA1 and bla RSA2 , were phylogenetically close to clinically important ESBLs like bla GES , bla BEL and bla L2 , and were further characterized for their substrate spectra. The blaRSA1 protein, encoded as an integron gene cassette, efficiently hydrolysed penicillins, first generation cephalosporins and cefotaxime, while blaRSA2 was an inducible class A beta-lactamase, capable of hydrolyzing carbapenems albeit with limited efficiency, similar to the L2 beta-lactamase from Stenotrophomonas maltophilia. All detected novel genes were associated with plasmid mobilization proteins, integrons, and/or other resistance genes, suggesting a potential for mobility. This study provides insight into a resistome shaped by an exceptionally strong and long-term antibiotic selection pressure. An improved knowledge of mobilized resistance factors in the external environment may make us better prepared for the resistance challenges that we may face in clinics in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.
REDUCTIVE DEHALOGENATION OF ORGANIC CONTAMINANTS IN SOILS AND GROUND WATER

EPA Science Inventory

Introduction and large scale production of synthetic halogenated organic chemicals over the last 50 years has resulted in a group of contaminants which tend to persist in the environment and resist both biotic and abiotic degradation. The low solubility of these types of contamin...
Assessment of Gamma Radiation Resistance of Spores Isolated from the Spacecraft Assembly Facility During MSL Assembly

NASA Technical Reports Server (NTRS)

Chopra, Arsh; Ramirez, Gustavo A.; Venkateswaran, Kasthuri J.; Vaishampayan, Parag A.

2011-01-01

Spore forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate extreme environmental conditions such as radiation, desiccation, and high temperatures. Since the Viking era (early 1970's), spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. There is a growing concern that desiccation and extreme radiation resistant spore forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequently proliferate on another solar body. Such forward contamination would certainly jeopardize future life detection or sample return technologies. It is important to recognize that different classes of organisms are critical while calculating the probability of contamination, and methods must be devised to estimate their abundances. Microorganisms can be categorized based on radiation sensitivity as Type A, B, C, and D. Type C represents spores resistant to radiation (10% or greater survival above 0.8 mRad gamma radiation). To address these questions we have purified 96 spore formers, isolated during planetary protection efforts of Mars Science Laboratory assembly for gamma radiation resistance. The spores purified and stored will be used to generate data that can be used further to model and predict the probability of forward contamination.
Assessment of Gamma Radiation Resistance of Spores Isolated from the Spacecraft Assembly Facility During MSL Assembly

NASA Technical Reports Server (NTRS)

Chopra, Arsh; Ramirez, Gustavo A.; Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.

2011-01-01

Spore forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate extreme environmental conditions such as radiation, desiccation, and high temperatures. Since the Viking era (early 1970's), spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. There is a growing concern that desiccation and extreme radiation resistant spore forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequently proliferate on another solar body. Such forward contamination would certainly jeopardize future life detection or sample return technologies. It is important to recognize that different classes of organisms are critical while calculating the probability of contamination, and methods must be devised to estimate their abundances. Microorganisms can be categorized based on radiation sensitivity as Type A, B, C, and D. Type C represents spores resistant to radiation (10% or greater survival above 0.8 Mrad gamma radiation). To address these questions we have purified 96 spore formers, isolated during planetary protection efforts of Mars Science Laboratory assembly for gamma radiation resistance. The spores purified and stored will be used to generate data that can be used further to model and predict the probability of forward contamination.

Human health risks associated with antimicrobial-resistant enterococci and Staphylococcus aureus on poultry meat.

PubMed

Bortolaia, V; Espinosa-Gongora, C; Guardabassi, L

2016-02-01

Enterococci and staphylococci are frequent contaminants on poultry meat. Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus are also well-known aetiological agents of a wide variety of infections resulting in major healthcare costs. This review provides an overview of the human health risks associated with the occurrence of these opportunistic human pathogens on poultry meat with particular focus on the risk of food-borne transmission of antimicrobial resistance. In the absence of conclusive evidence of transmission, this risk was inferred using data from scientific articles and national reports on prevalence, bacterial load, antimicrobial resistance and clonal distribution of these three species on poultry meat. The risks associated with ingestion of antimicrobial-resistant enterococci of poultry origin comprise horizontal transfer of resistance genes and transmission of multidrug-resistant E. faecalis lineages such as sequence type ST16. Enterococcus faecium lineages occurring in poultry meat products are distantly related to those causing hospital-acquired infections but may act as donors of quinupristin/dalfopristin resistance and other resistance determinants of clinical interest to the human gut microbiota. Ingestion of poultry meat contaminated with S. aureus may lead to food poisoning. However, antimicrobial resistance in the toxin-producing strains does not have clinical implications because food poisoning is not managed by antimicrobial therapy. Recently methicillin-resistant S. aureus of livestock origin has been reported on poultry meat. In theory handling or ingestion of contaminated meat is a potential risk factor for colonization by methicillin-resistant S. aureus. However, this risk is presently regarded as negligible by public health authorities. Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
Alleviation of phytotoxic effects of cadmium on rice seedlings by cadmium resistant PGPR strain Enterobacter aerogenes MCC 3092.

PubMed

Pramanik, Krishnendu; Mitra, Soumik; Sarkar, Anumita; Maiti, Tushar Kanti

2018-06-05

Heavy metal resistant PGPR mediated bioremediation, phytostimulation and stress alleviation is an eco-friendly method for sustainable agriculture in the metal contaminated soil. The isolation of such PGPR is highly demanding to reduce heavy metals in contaminated cultivated fields for agricultural benefit. The present study was successful to isolate a potent multi-heavy metal resistant PGPR strain, identified as Enterobacter aerogenes strain K6 based on MALDI-TOF MS, FAME analysis and 16S rDNA sequence homology, from rice rhizosphere contaminated with a variety of heavy metals/metalloid near industrial area. The strain exhibited high degree of resistance to Cd 2+ , Pb 2+ and As 3+ upto 4000 μg/mL, 3800 μg/mL and 1500 μg/mL respectively. Intracellular Cd accumulation of this strain was evidenced by AAS-SEM-TEM-EDX-XRF studies. Moreover, it showed several important PGP traits like IAA production, nitrogen fixation, phosphate solubilization, ACC deaminase activity even under high Cd stress (upto 3000 μg/mL). The combined effect of Cd resistance and PGP activities of this strain was manifested to the significant (p < 0.05) growth promotion of rice seedling under Cd stress by reducing oxidative stress (through antioxidants), stress ethylene and Cd uptake in seedlings. Thus K6 strain conferred Cd-tolerance in rice seedlings and could be applied as PGPR in contaminated fields. Copyright © 2018 Elsevier B.V. All rights reserved.
Long-term ERT monitoring of biogeochemical changes of an aged hydrocarbon contamination.

PubMed

Caterina, David; Flores Orozco, Adrian; Nguyen, Frédéric

2017-06-01

Adequate management of contaminated sites requires information with improved spatio-temporal resolution, in particular to assess bio-geochemical processes, such as the transformation and degradation of contaminants, precipitation of minerals or changes in groundwater geochemistry occurring during and after remediation procedures. Electrical Resistivity Tomography (ERT), a geophysical method sensitive to pore-fluid and pore-geometry properties, permits to gain quasi-continuous information about subsurface properties in real-time and has been consequently widely used for the characterization of hydrocarbon-impacted sediments. However, its application for the long-term monitoring of processes accompanying natural or engineered bioremediation is still difficult due to the poor understanding of the role that biogeochemical processes play in the electrical signatures. For in-situ studies, the task is further complicated by the variable signal-to-noise ratio and the variations of environmental parameters leading to resolution changes in the electrical images. In this work, we present ERT imaging results for data collected over a period of two years on a site affected by a diesel fuel contamination and undergoing bioremediation. We report low electrical resistivity anomalies in areas associated to the highest contaminant concentrations likely due transformations of the contaminant due to microbial activity and accompanying release of metabolic products. We also report large seasonal variations of the bulk electrical resistivity in the contaminated areas in correlation with temperature and groundwater level fluctuations. However, the amplitude of bulk electrical resistivity variations largely exceeds the amplitude expected given existing petrophysical models. Our results suggest that the variations in electrical properties are mainly controlled by microbial activity which in turn depends on soil temperature and hydrogeological conditions. Therefore, ERT can be suggested as a promising tool to track microbial activity during bioremediation even though further research is still needed to completely understand the bio-geochemical processes involved and their impact on electrical signatures. Copyright © 2017 Elsevier B.V. All rights reserved.
Long-term ERT monitoring of biogeochemical changes of an aged hydrocarbon contamination

NASA Astrophysics Data System (ADS)

Caterina, David; Flores Orozco, Adrian; Nguyen, Frédéric

2017-06-01

Adequate management of contaminated sites requires information with improved spatio-temporal resolution, in particular to assess bio-geochemical processes, such as the transformation and degradation of contaminants, precipitation of minerals or changes in groundwater geochemistry occurring during and after remediation procedures. Electrical Resistivity Tomography (ERT), a geophysical method sensitive to pore-fluid and pore-geometry properties, permits to gain quasi-continuous information about subsurface properties in real-time and has been consequently widely used for the characterization of hydrocarbon-impacted sediments. However, its application for the long-term monitoring of processes accompanying natural or engineered bioremediation is still difficult due to the poor understanding of the role that biogeochemical processes play in the electrical signatures. For in-situ studies, the task is further complicated by the variable signal-to-noise ratio and the variations of environmental parameters leading to resolution changes in the electrical images. In this work, we present ERT imaging results for data collected over a period of two years on a site affected by a diesel fuel contamination and undergoing bioremediation. We report low electrical resistivity anomalies in areas associated to the highest contaminant concentrations likely due transformations of the contaminant due to microbial activity and accompanying release of metabolic products. We also report large seasonal variations of the bulk electrical resistivity in the contaminated areas in correlation with temperature and groundwater level fluctuations. However, the amplitude of bulk electrical resistivity variations largely exceeds the amplitude expected given existing petrophysical models. Our results suggest that the variations in electrical properties are mainly controlled by microbial activity which in turn depends on soil temperature and hydrogeological conditions. Therefore, ERT can be suggested as a promising tool to track microbial activity during bioremediation even though further research is still needed to completely understand the bio-geochemical processes involved and their impact on electrical signatures.
Capabilities of the Materials Contamination Team at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Burns, H. D.; Finckenor, M. M.; Boothe, R. E.; Albyn, K. C.; Finchum, C. A.

2003-01-01

The Materials Contamination Team of the Environmental Effects Group, Materials, Processes, and Manufacturing Department, has been recognized for its contribution to space flight, including space transportation, space science and flight projects, such as the reusable solid rocket motor, Chandra X-Ray Observatory, and the International Space Station. The Materials Contamination Team s realm of responsibility encompasses all phases of hardware development including design, manufacturing, assembly, test, transportation, launch-site processing, on-orbit exposure, return, and refurbishment if required. Contamination is a concern in the Space Shuttle with sensitivity bondlines and reactive fluid (liquid oxygen) compatibility as well as for sensitive optics, particularly spacecraft such as Hubble Space Telescope and Chandra X-Ray Observatory. The Materials Contamination Team has a variety of facilities and instrumentation capable of contaminant detection identification, and monitoring. The team addresses material applications dealing with environments, including production facilities, clean rooms, and on-orbit exposure. The team of engineers and technicians also develop and evaluates new surface cleanliness inspection technologies. Databases are maintained by the team for proces! materials as well as outgassing and optical compatibility test results for specific environments.
Prevalence and antibiogram study of Salmonella and Staphylococcus aureus in poultry meat

PubMed Central

Akbar, Ali; Anal, Anil Kumar

2013-01-01

Objective To evaluate the presence and antibiogram pattern of Salmonella and Staphylococcus aureus (S. aureus) in retail poultry meat products. Methods Foodborne pathogens (Salmonella and S. aureus) were isolated from poultry meat and confirmed with the help of biochemical and immunological test. Antibiogram of the isolates were examined by following CLSI methods. Results A total number of 209 poultry meat samples were collected and studied in this study. Out of which, 5.26% were found contaminated with Salmonella while 18.18% were found contaminated with S. aureus. All the Salmonella and S. aureus isolates were found resistant to at least one antibiotic. About 72.72% of the Salmonella isolates showed resistance to tetracycline, while S. aureus isolates were also found highly resistant to tetracycline equal to 44.73%. One of the Salmonella isolates showed multi-drug resistance to almost six antibiotics out of nine antibiotics used in the study. Multidrug resistant S. aureus isolates were also found in the study. Conclusions The study confirmed the presence of Salmonella and S. aureus in retail poultry meat. It is a potential threat to consumer health. To reduce the risk of contamination, good hygiene practices are necessary from processing to storage. PMID:23593598
Enzymatic bioremediation of polyaromatic hydrocarbons by fungal consortia enriched from petroleum contaminated soil and oil seeds.

PubMed

Balaji, V; Arulazhagan, P; Ebenezer, P

2014-05-01

The present study focuses on fungal strains capable of secreting extracellular enzymes by utilizing hydrocarbons present in the contaminated soil. Fungal strains were enriched from petroleum hydrocarbons contaminated soil samples collected from Chennai city, India. The potential fungi were isolated and screened for their enzyme secretion such as lipase, laccase, peroxidase and protease and also evaluated fungal enzyme mediated PAHs degradation. Total, 21 potential PAHs degrading fungi were isolated from PAHs contaminated soil, which belongs to 9 genera such as Aspergillus, Curvularia, Drechslera, Fusarium, Lasiodiplodia, Mucor Penicillium, Rhizopus, Trichoderma, and two oilseed-associated fungal genera such as Colletotrichum and Lasiodiplodia were used to test their efficacy in degradation of PAHs in polluted soil. Maximum lipase production was obtained with P. chrysogenum, M. racemosus and L. theobromae VBE1 under optimized cultural condition, which utilized PAHs in contaminated soil as sole carbon source. Fungal strains, P. chrysogenum, M. racemosus and L. theobromae VBE1, as consortia, used in the present study were capable of degrading branched alkane isoprenoids such as pristine (C17) and pyrene (C18) present in PAHs contaminated soil with high lipase production. The fungal consortia acts as potential candidate for bioremediation of PAHs contaminated environments.
Lessons Learned from the Hubble Space Telescope (HST) Contamination Control Program

NASA Technical Reports Server (NTRS)

Hansen, Patricia A.; Townsend, Jacqueline A.; Hedgeland, Randy J.

2004-01-01

Over the past two decades, the Hubble Space Telescope (HST) Contamination Control Program has evolved from a ground-based integration program to a space-based science-sustaining program. The contamination controls from the new-generation Scientific Instruments and Orbital Replacement Units were incorporated into the HST Contamination Control Program to maintain scientific capability over the life of the telescope. Long-term on-orbit scientific data has shown that these contamination controls implemented for the instruments, Servicing Mission activities (Orbiter, Astronauts, and mission), and on-orbit operations successfully protected the HST &om contamination and the instruments from self-contamination.
Lessons Learned from the Hubble Space Telescope (HST) Contamination Control Program

NASA Technical Reports Server (NTRS)

Hansen, Patricia A.; Townsend, Jacqueline A.; Hedgeland, Randy J.

2004-01-01

Over the past two decades, the Hubble Space Telescope (HST) Contamination Control Program has evolved from a ground-based integration program to a space-based science-sustaining program. The contamination controls from the new-generation Scientific Instruments and Orbital Replacement Units were incorporated into the HST Contamination Control Program to maintain scientific capability over the life of the telescope. Long-term on-orbit scientific data has shown that these contamination controls implemented for the instruments, Servicing Mission activities (Orbiter, Astronauts, and mission), and on-orbit operations successfully protected the HST from contamination and the instruments from self-contamination.
Delineation of soil and groundwater contamination using geophysical methods at a waste disposal site in Canakkale, Turkey.

PubMed

Kaya, M Ali; Ozürlan, Gülçin; Sengül, Ebru

2007-12-01

Direct current (DC) resistivity, self potential (SP) and very low frequency electromagnetic (VLF-EM) measurements are carried out to detect the spread of groundwater contamination and to locate possible pathways of leachate plumes, that resulted from an open waste disposal site of Canakkale municipality. There is no proper management of the waste disposal site in which industrial and domestic wastes were improperly dumped. Furthermore, because of the dumpsite is being located at the catchment area borders of a small creek and is being topographically at a high elevation relative to the urban area, the groundwater is expected to be hazardously contaminated. Interpretations of DC resistivity geoelectrical data showed a low resistivity zone (<5 ohm-m), which appears to be a zone, that is fully saturated with leachate from an open dumpsite. The VLF-EM and SP method, support the results of geoelectrical method relating a contaminated zone in the survey area. There is a good correlation between the geophysical investigations and the results of previously collected geochemical and hydrochemical measurements.
Effect of soil biochar amendment on grain crop resistance to Fusarium mycotoxin contamination

USDA-ARS?s Scientific Manuscript database

Mycotoxin contamination of food and feed is among the top food safety concerns. Fusarium spp. cause serious diseases in cereal crops reducing yield and contaminating grain with mycotoxins that can be deleterious to human and animal health. Fusarium graminearum and Fusarium verticillioides infect whe...
OCCURRENCE OF MERCURY-RESISTANT MICROORGANISMS IN MERCURY-CONTAMINATED SOILS AND SEDIMENTS IN PAVLODAR, KAZAKHSTAN

EPA Science Inventory

There is extensive mercury contamination of soil surrounding a chloralkali plant in Pavlodar, Kazakhstan that operated from 1970 to 1990. High-level mercury contamination exists within the confines of the plant, at nearby off-site waste storage and evaporation ponds, and in Balky...
OCCURRENCE OF MICROORGANISMS RESISTANT TO MERCURY IN MERCURY CONTAMINATED SOILS AND SEDIMENTS IN PAVLODAR, KAZAKHSTAN

EPA Science Inventory

There is extensive mercury contamination of soil surrounding a chloralkali plant in Pavlodar, Kazakhstan that operated from 1970 to 1990. High-level mercury contamination exists within the confines of the plant, at nearby off-site waste storage and evaporation ponds, and in Balky...
Resistively-Heated Microlith-based Adsorber for Carbon Dioxide and Trace Contaminant Removal

NASA Technical Reports Server (NTRS)

Roychoudhury, S.; Walsh, D.; Perry, J.

2005-01-01

An integrated sorber-based Trace Contaminant Control System (TCCS) and Carbon Dioxide Removal Assembly (CDRA) prototype was designed, fabricated and tested. It corresponds to a 7-person load. Performance over several adsorption/regeneration cycles was examined. Vacuum regenerations at effective time/temperature conditions, and estimated power requirements were experimentally verified for the combined CO2/trace contaminant removal prototype. The current paper details the design and performance of this prototype during initial testing at CO2 and trace contaminant concentrations in the existing CDRA, downstream of the drier. Additional long-term performance characterization is planned at NASA. Potential system design options permitting associated weight, volume savings and logistic benefits, especially as relevant for long-duration space flight, are reviewed. The technology consisted of a sorption bed with sorbent- coated metal meshes, trademarked and patented as Microlith by Precision Combustion, Inc. (PCI). By contrast the current CO2 removal system on the International Space Station employs pellet beds. Preliminary bench scale performance data (without direct resistive heating) for simultaneous CO2 and trace contaminant removal was reviewed in SAE 2004-01-2442. In the prototype, the meshes were directly electrically heated for rapid response and accurate temperature control. This allowed regeneration via resistive heating with the potential for shorter regeneration times, reduced power requirement, and net energy savings vs. conventional systems. A novel flow arrangement, for removing both CO2 and trace contaminants within the same bed, was demonstrated. Thus, the need for a separate trace contaminant unit was eliminated resulting in an opportunity for significant weight savings. Unlike the current disposable charcoal bed, zeolites for trace contaminant removal are amenable to periodic regeneration.
Assessment of Ni accumulation capability by fungi for a possible approach to remove metals from soils and waters.

PubMed

Cecchi, Grazia; Roccotiello, Enrica; Di Piazza, Simone; Riggi, Alex; Mariotti, Mauro Giorgio; Zotti, Mirca

2017-03-04

Abandoned industrial sites and mines may constitute possible hazards for surrounding environment due to the presence of toxic compounds that may contaminate soils and waters. The possibility to remove metal contaminants, specifically nickel (Ni), by means of fungi was presented exploiting a set of fungal strains isolated from a Ligurian dismissed mine. The achieved results demonstrate the high Ni(II) tolerance, up to 500 mg Ni l -1 , and removal capability of a Trichoderma harzianum strain. This latter hyperaccumulates up to 11,000 mg Ni kg -1 , suggesting its possible use in a bioremediation protocol able to provide a sustainable reclamation of broad contaminated areas.
Diversity of Antimicrobial Resistance and Virulence Determinants in Pseudomonas aeruginosa Associated with Fresh Vegetables

PubMed Central

Allydice-Francis, Kashina; Brown, Paul D.

2012-01-01

With the increased focus on healthy eating and consuming raw vegetables, this study assessed the extent of contamination of fresh vegetables by Pseudomonas aeruginosa in Jamaica and examined the antibiotic susceptibility profiles and the presence of various virulence associated determinants of P. aeruginosa. Analyses indicated that vegetables from retail markets and supermarkets were widely contaminated by P. aeruginosa; produce from markets were more frequently contaminated, but the difference was not significant. Lettuce and carrots were the most frequently contaminated vegetables, while tomatoes were the least. Pigment production (Pyoverdine, pyocyanin, pyomelanin and pyorubin), fluorescein and alginate were common in these isolates. Imipenem, gentamicin and ciprofloxacin were the most inhibitory antimicrobial agents. However, isolates were resistant or showed reduced susceptibility to ampicillin, chloramphenicol, sulphamethoxazole/trimethoprim and aztreonam, and up to 35% of the isolates were resistant to four antimicrobial agents. As many as 30% of the isolates were positive for the fpv1 gene, and 13% had multiple genes. Sixty-four percent of the isolates harboured an exoenzyme gene (exoS, exoT, exoU or exoY), and multiple exo genes were common. We conclude that P. aeruginosa is a major contaminant of fresh vegetables, which might be a source of infection for susceptible persons within the community. PMID:23213336
Effect of System Contaminants on the Performance of a Proton Exchange Membrane Fuel Cell

DOE PAGES

Mehrabadi, Bahareh Alsadat Tavakoli; Dinh, Huyen N.; Bender, Guido; ...

2016-11-10

The performance loss and recovery of the fuel cell due to Balance of Plant (BOP) contaminants was identified via a combination of experimental data and a mathematical model. The experiments were designed to study the influence of organic contaminants (e.g. those from BOP materials) on the resistance of the catalyst, ionomer and membrane, and a mathematical model was developed that allowed us to separate these competing resistances from the data collected on an operating fuel cell. For this reason, based on the functional groups, four organic contaminants found in BOP materials, diethylene glycol monoethyl ether (DGMEE), diethylene glycol monoethyl ethermore » acetate (DGMEA), benzyl alcohol (BzOH) and 2,6-diaminotoluene (2,6-DAT) were infused separately to the cathode side of the fuel cell. The cell voltage and high frequency impedance resistance was measured as a function of time. The contaminant feed was then discontinued and voltage recovery was measured. It was determined that compounds with ion exchange properties like 2,6-DAT can cause voltage loss with non-reversible recovery, so this compound was studied in more detail. Finally, the degree of voltage loss increased with an increase in concentration, and/or infusion time, and increased with a decrease in catalyst loadings.« less
Water Access, Sanitation, and Hygiene Conditions and Health Outcomes among Two Settlement Types in Rural Far North Cameroon.

PubMed

Gorham, Tyler J; Yoo, Joshua; Garabed, Rebecca; Mouhaman, Arabi; Lee, Jiyoung

2017-04-20

The Far North region in Cameroon has been more heavily impacted by cholera than any other region over the past decade, but very little has been done to study the drivers of waterborne diseases in the region. We investigated the relationship between water, sanitation, and hygiene (WASH) parameters, microbial and antibiotic resistance (AR) contamination levels in drinking water, and health outcomes using health survey and molecular analysis during June and July of 2014 in two settlement types (agro-pastoralist villages and transhumant pastoralist camps). Quantitative polymerase chain reaction was used to determine fecal contamination sources, enteric pathogens, and antibiotic resistance genes. Ruminant-associated fecal contamination was widespread in both settlement types (81.2%), with human-associated contamination detected in 21.7% of the samples. Salmonella spp. (59.4%) and Shiga toxin-producing E. coli ( stx 1 44.9% and stx 2 31.9%) were detected across all samples. Tetracycline resistance was found only in village samples. A significant difference in diarrheal incidence within the past 28 days among young children was found between camps (31.3%) and villages (0.0%). Our findings suggest that water contamination may play an important role in contributing to gastrointestinal illness, supporting the need for future research and public health intervention to reduce gastrointestinal illness in the area.
Antimicrobial Resistance in the Food Chain: A Review

PubMed Central

Verraes, Claire; Van Boxstael, Sigrid; Van Meervenne, Eva; Van Coillie, Els; Butaye, Patrick; Catry, Boudewijn; de Schaetzen, Marie-Athénaïs; Van Huffel, Xavier; Imberechts, Hein; Dierick, Katelijne; Daube, George; Saegerman, Claude; De Block, Jan; Dewulf, Jeroen; Herman, Lieve

2013-01-01

Antimicrobial resistant zoonotic pathogens present on food constitute a direct risk to public health. Antimicrobial resistance genes in commensal or pathogenic strains form an indirect risk to public health, as they increase the gene pool from which pathogenic bacteria can pick up resistance traits. Food can be contaminated with antimicrobial resistant bacteria and/or antimicrobial resistance genes in several ways. A first way is the presence of antibiotic resistant bacteria on food selected by the use of antibiotics during agricultural production. A second route is the possible presence of resistance genes in bacteria that are intentionally added during the processing of food (starter cultures, probiotics, bioconserving microorganisms and bacteriophages). A last way is through cross-contamination with antimicrobial resistant bacteria during food processing. Raw food products can be consumed without having undergone prior processing or preservation and therefore hold a substantial risk for transfer of antimicrobial resistance to humans, as the eventually present resistant bacteria are not killed. As a consequence, transfer of antimicrobial resistance genes between bacteria after ingestion by humans may occur. Under minimal processing or preservation treatment conditions, sublethally damaged or stressed cells can be maintained in the food, inducing antimicrobial resistance build-up and enhancing the risk of resistance transfer. Food processes that kill bacteria in food products, decrease the risk of transmission of antimicrobial resistance. PMID:23812024
Identification and Assessment of the Behavior of Methicillin-Resistant Staphylococci in Cheese.

PubMed

Steinka, Izabela

2018-03-22

This study was carried out with the aim of identifying and assessing methicillin-resistant Staphylococcus aureus (MRSA) during lactic acid cheese storage. The study involved 30 assortments of lactic acid cheese and 21 cheeses with S. aureus TWP11616 (MRSA). Results showed low MRSA contamination levels in lactic acid cheese. The majority of cow and goat lactic acid cheese samples (more than 72%) were characterized by a low level of MRSA (≤10 CFU/g). With regard to cow and sheep lactic acid cheese, methicillin-resistant Staphylococcus spp. contamination levels of ≥100 CFU/g were found in 88 and 100% of samples, respectively. The microbial dynamics of MRSA changes in lactic acid cheese suggest a significant reduction in contamination levels after 4 days of product storage, and this decrease is likely not dependent on the type of packaging method.

A Coupled model for ERT monitoring of contaminated sites

NASA Astrophysics Data System (ADS)

Wang, Yuling; Zhang, Bo; Gong, Shulan; Xu, Ya

2018-02-01

The performance of electrical resistivity tomography (ERT) system is usually investigated using a fixed resistivity distribution model in numerical simulation study. In this paper, a method to construct a time-varying resistivity model by coupling water transport, solute transport and constant current field is proposed for ERT monitoring of contaminated sites. Using the proposed method, a monitoring model is constructed for a contaminated site with a pollution region on the surface and ERT monitoring results at different time is calculated by the finite element method. The results show that ERT monitoring profiles can effectively reflect the increase of the pollution area caused by the diffusion of pollutants, but the extent of the pollution is not exactly the same as the actual situation. The model can be extended to any other case and can be used to scheme design and results analysis for ERT monitoring.
Antibiotic-resistant fecal bacteria, antibiotics, and mercury in surface waters of Oakland County, Michigan, 2005-2006

USGS Publications Warehouse

Fogarty, Lisa R.; Duris, Joseph W.; Crowley, Suzanne L.; Hardigan, Nicole

2007-01-01

Water samples collected from 20 stream sites in Oakland and Macomb Counties, Mich., were analyzed to learn more about the occurrence of cephalosporin-resistant Escherichia coli (E. coli) and vancomycin-resistant enterococci (VRE) and the co-occurrence of antibiotics and mercury in area streams. Fecal indicator bacteria concentrations exceeded the Michigan recreational water-quality standard of 300 E. coli colony forming units (CFU) per 100 milliliters of water in 19 of 35 stream-water samples collected in Oakland County. A gene commonly associated with enterococci from humans was detected in samples from Paint Creek at Rochester and Evans Ditch at Southfield, indicating that human fecal waste is a possible source of fecal contamination at these sites. E. coli resistant to the cephalosporin antibiotics (cefoxitin and/ or ceftriaxone) were found at all sites on at least one occasion. The highest percentages of E. coli isolates resistant to cefoxitin and ceftriaxone were 71 percent (Clinton River at Auburn Hills) and 19 percent (Sashabaw Creek near Drayton Plains), respectively. Cephalosporin-resistant E. coli was detected more frequently in samples from intensively urbanized or industrialized areas than in samples from less urbanized areas. VRE were not detected in any sample collected in this study. Multiple antibiotics (azithromycin, erythromycin, ofloxacin, sulfamethoxazole, and trimethoprim) were detected in water samples from the Clinton River at Auburn Hills, and tylosin (an antibiotic used in veterinary medicine and livestock production that belongs to the macrolide group, along with erythromycin) was detected in one water sample from Paint Creek at Rochester. Concentrations of total mercury were as high as 19.8 nanograms per liter (Evans Ditch at Southfield). There was no relation among percentage of antibiotic-resistant bacteria and measured concentrations of antibiotics or mercury in the water. Genetic elements capable of exchanging multiple antibiotic-resistance genes (class I integrons) were detected in several samples, indicating that the resistance carried by these organisms may be transferable to other bacteria, including disease-causing bacteria.
Comparison of the Antimicrobial and Sanitizer Resistance of Salmonella Isolates from Chicken Slaughter Processes in Korea.

PubMed

Youn, So Youn; Jeong, Ok Mi; Choi, Byung Kook; Jung, Suk Chan; Kang, Min Su

2017-03-01

Salmonella is a foodborne pathogen worldwide. Outbreaks of Salmonella are commonly associated with consumption of contaminated foods such as poultry products. Therefore, the objective of this study was to determine the occurrence, biofilm formation, antibiotic resistance, and sanitizer resistance of Salmonella enterica isolated from chicken carcasses. A total of 318 samples were collected from 15 chicken slaughterhouses in 8 provinces of Korea. They were then examined for Salmonella contamination. S. enterica isolates were tested for their susceptibilities to 15 antimicrobials by broth microdilution method. Their biofilm formation ability and resistance to sanitizers were also evaluated. Eighty-two isolates of S. enterica were obtained from the 318 samples. There were 14 serotypes and 2 untypable isolates. Fifty-seven (69.5%) isolates were resistant to at least one antibiotic while 30 (36.6%) isolates were resistant to 5 or more antibiotics. Two S. Senftenberg and 3 S. Montevideo isolates exhibited considerable biofilm formation ability (A 600 >0.2) following incubation in Luria-Bertani (LB) broth for 48 h. Biofilm cell survival and recovery growth assay after sanitization showed that most isolates were highly susceptible to 2.5% lactic acid and 0.1% cetylpyridinium chloride. Therefore, lactic acid and cetylpyridinium chloride might be alternatively or additionally used in addition to chlorine-based sanitizers that are frequently used to reduce Salmonella contamination of chicken carcasses. Our results provide basic information on the distribution of Salmonella serotypes in chicken slaughterhouses. This study also highlights the necessity to improve farming practices and use antimicrobial agents cautiously. This study also suggests that sanitization during the slaughtering process might be necessary to reduce Salmonella contamination of chicken carcasses. © 2017 Institute of Food Technologists®.
Risk of Transmission of Antimicrobial Resistant Escherichia coli from Commercial Broiler and Free-Range Retail Chicken in India

PubMed Central

Hussain, Arif; Shaik, Sabiha; Ranjan, Amit; Nandanwar, Nishant; Tiwari, Sumeet K.; Majid, Mohammad; Baddam, Ramani; Qureshi, Insaf A.; Semmler, Torsten; Wieler, Lothar H.; Islam, Mohammad A.; Chakravortty, Dipshikha; Ahmed, Niyaz

2017-01-01

Multidrug-resistant Escherichia coli infections are a growing public health concern. This study analyzed the possibility of contamination of commercial poultry meat (broiler and free-range) with pathogenic and or multi-resistant E. coli in retail chain poultry meat markets in India. We analyzed 168 E. coli isolates from broiler and free-range retail poultry (meat/ceca) sampled over a wide geographical area, for their antimicrobial sensitivity, phylogenetic groupings, virulence determinants, extended-spectrum-β-lactamase (ESBL) genotypes, fingerprinting by Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR and genetic relatedness to human pathogenic E. coli using whole genome sequencing (WGS). The prevalence rates of ESBL producing E. coli among broiler chicken were: meat 46%; ceca 40%. Whereas, those for free range chicken were: meat 15%; ceca 30%. E. coli from broiler and free-range chicken exhibited varied prevalence rates for multi-drug resistance (meat 68%; ceca 64% and meat 8%; ceca 26%, respectively) and extraintestinal pathogenic E. coli (ExPEC) contamination (5 and 0%, respectively). WGS analysis confirmed two globally emergent human pathogenic lineages of E. coli, namely the ST131 (H30-Rx subclone) and ST117 among our poultry E. coli isolates. These results suggest that commercial poultry meat is not only an indirect public health risk by being a possible carrier of non-pathogenic multi-drug resistant (MDR)-E. coli, but could as well be the carrier of human E. coli pathotypes. Further, the free-range chicken appears to carry low risk of contamination with antimicrobial resistant and extraintestinal pathogenic E. coli (ExPEC). Overall, these observations reinforce the understanding that poultry meat in the retail chain could possibly be contaminated by MDR and/or pathogenic E. coli. PMID:29180984
Risk of Transmission of Antimicrobial Resistant Escherichia coli from Commercial Broiler and Free-Range Retail Chicken in India.

PubMed

Hussain, Arif; Shaik, Sabiha; Ranjan, Amit; Nandanwar, Nishant; Tiwari, Sumeet K; Majid, Mohammad; Baddam, Ramani; Qureshi, Insaf A; Semmler, Torsten; Wieler, Lothar H; Islam, Mohammad A; Chakravortty, Dipshikha; Ahmed, Niyaz

2017-01-01

Multidrug-resistant Escherichia coli infections are a growing public health concern. This study analyzed the possibility of contamination of commercial poultry meat (broiler and free-range) with pathogenic and or multi-resistant E. coli in retail chain poultry meat markets in India. We analyzed 168 E. coli isolates from broiler and free-range retail poultry (meat/ceca) sampled over a wide geographical area, for their antimicrobial sensitivity, phylogenetic groupings, virulence determinants, extended-spectrum-β-lactamase (ESBL) genotypes, fingerprinting by Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR and genetic relatedness to human pathogenic E. coli using whole genome sequencing (WGS). The prevalence rates of ESBL producing E. coli among broiler chicken were: meat 46%; ceca 40%. Whereas, those for free range chicken were: meat 15%; ceca 30%. E. coli from broiler and free-range chicken exhibited varied prevalence rates for multi-drug resistance (meat 68%; ceca 64% and meat 8%; ceca 26%, respectively) and extraintestinal pathogenic E. coli (ExPEC) contamination (5 and 0%, respectively). WGS analysis confirmed two globally emergent human pathogenic lineages of E. coli , namely the ST131 ( H 30-Rx subclone) and ST117 among our poultry E. coli isolates. These results suggest that commercial poultry meat is not only an indirect public health risk by being a possible carrier of non-pathogenic multi-drug resistant (MDR)- E. coli , but could as well be the carrier of human E. coli pathotypes. Further, the free-range chicken appears to carry low risk of contamination with antimicrobial resistant and extraintestinal pathogenic E. coli (ExPEC). Overall, these observations reinforce the understanding that poultry meat in the retail chain could possibly be contaminated by MDR and/or pathogenic E. coli.
Mixed biofilm formation by Shiga toxin-producing Escherichia coli and Salmonella enterica serovar Typhimurium enhanced bacterial resistance to sanitization due to extracellular polymeric substances.

PubMed

Wang, Rong; Kalchayanand, Norasak; Schmidt, John W; Harhay, Dayna M

2013-09-01

Shiga toxin-producing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium are important foodborne pathogens capable of forming single-species biofilms or coexisting in multispecies biofilm communities. Bacterial biofilm cells are usually more resistant to sanitization than their planktonic counterparts, so these foodborne pathogens in biofilms pose a serious food safety concern. We investigated how the coexistence of E. coli O157:H7 and Salmonella Typhimurium strains would affect bacterial planktonic growth competition and mixed biofilm composition. Furthermore, we also investigated how mixed biofilm formation would affect bacterial resistance to common sanitizers. Salmonella Typhimurium strains were able to outcompete E. coli strains in the planktonic growth phase; however, mixed biofilm development was highly dependent upon companion strain properties in terms of the expression of bacterial extracellular polymeric substances (EPS), including curli fimbriae and exopolysaccharide cellulose. The EPS-producing strains with higher biofilm-forming abilities were able to establish themselves in mixed biofilms more efficiently. In comparison to single-strain biofilms, Salmonella or E. coli strains with negative EPS expression obtained significantly enhanced resistance to sanitization by forming mixed biofilms with an EPS-producing companion strain of the other species. These observations indicate that the bacterial EPS components not only enhance the sanitizer resistance of the EPS-producing strains but also render protections to their companion strains, regardless of species, in mixed biofilms. Our study highlights the potential risk of cross-contamination by multispecies biofilms in food safety and the need for increased attention to proper sanitization practices in food processing facilities.
Extraction of contaminants from a gas

DOEpatents

Babko-Malyi, Sergei

2000-01-01

A method of treating industrial gases to remove contaminants is disclosed. Ions are generated in stream of injectable gas. These ions are propelled through the contaminated gas as it flows through a collection unit. An electric field is applied to the contaminated gas. The field causes the ions to move through the contaminated gases, producing electrical charges on the contaminants. The electrically charged contaminants are then collected at one side of the electric field. The injectable gas is selected to produce ions which will produce reactions with particular contaminants. The process is thus capable of removing particular contaminants. The process does not depend on diffusion as a transport mechanism and is therefore suitable for removing contaminants which exist in very low concentrations.
Apparatus for extraction of contaminants from a gas

DOEpatents

Babko-Malyi, Sergei

2001-01-01

A method of treating industrial gases to remove contaminants is disclosed. Ions are generated in stream of injectable gas. These ions are propelled through the contaminated gas as it flows through a collection unit. An electric field is applied to the contaminated gas. The field causes the ions to move through the contaminated gases, producing electrical charges on the contaminants. The electrically charged contaminants are then collected at one side of the electric field. The injectable gas is selected to produce ions which will produce reactions with particular contaminants. The process is thus capable of removing particular contaminants. The process does not depend on diffusion as a transport mechanism and is therefore suitable for removing contaminants which exist in very low concentrations.
INFECUNDITY AND CONSUMPTION OF PCB-CONTAMINATED SPORT FISH

EPA Science Inventory

Biologic capacity for reproduction, or fecundity, may be threatened by environmental contaminants, especially compounds capable of disrupting endocrine pathways. Telephone interviews that focused on reproductive events were conducted with female members of the New York State Angl...
Remediating Contaminant Plumes in Groundwater with Shallow Excavations Containing Coarse Reactive Media.

PubMed

Hudak, Paul F

2018-02-01

A groundwater flow and mass transport model tested the capability of shallow excavations filled with coarse, reactive media to remediate a hypothetical unconfined aquifer with a maximum saturated thickness of 5 m. Modeled as contaminant sinks, the rectangular excavations were 10 m downgradient of an initial contaminant plume originating from a source at the top of the aquifer. The initial plume was approximately 259 m long, 23 m wide, and 5 m thick, with a downgradient tip located approximately 100 m upgradient of the site boundary. The smallest trench capable of preventing offsite migration was 11 m long (measured perpendicular to groundwater flow), 4 m wide (measured parallel to groundwater flow), and 3 m deep. Results of this study suggest that shallow trenches filled with coarse filter media that partially penetrate unconfined aquifers may be a viable alternative for remediating contaminated groundwater at some sites.
Evaluation and study of advanced optical contamination, deposition, measurement, and removal techniques. [including computer programs and ultraviolet reflection analysis

NASA Technical Reports Server (NTRS)

Linford, R. M. F.; Allen, T. H.; Dillow, C. F.

1975-01-01

A program is described to design, fabricate and install an experimental work chamber assembly (WCA) to provide a wide range of experimental capability. The WCA incorporates several techniques for studying the kinetics of contaminant films and their effect on optical surfaces. It incorporates the capability for depositing both optical and contaminant films on temperature-controlled samples, and for in-situ measurements of the vacuum ultraviolet reflectance. Ellipsometer optics are mounted on the chamber for film thickness determinations, and other features include access ports for radiation sources and instrumentation. Several supporting studies were conducted to define specific chamber requirements, to determine the sensitivity of the measurement techniques to be incorporated in the chamber, and to establish procedures for handling samples prior to their installation in the chamber. A bibliography and literature survey of contamination-related articles is included.
Analytical model of contamination during the drying of cylinders of jamonable muscle

NASA Astrophysics Data System (ADS)

Montoya Arroyave, Isabel

2014-05-01

For a cylinder of jamonable muscle of radius R and length much greater than R; considering that the internal resistance to the transfer of water is much greater than the external and that the internal resistance is one certain function of the distance to the axis; the distribution of the punctual moisture in the jamonable cylinder is analytically computed in terms of the Bessel's functions. During the process of drying and salted the jamonable cylinder is sensitive to contaminate with bacterium and protozoa that come from the environment. An analytical model of contamination is presents using the diffusion equation with sources and sinks, which is solve by the method of the Laplace transform, the Bromwich integral, the residue theorem and some special functions like Bessel and Heun. The critical times intervals of drying and salted are computed in order to obtain the minimum possible contamination. It is assumed that both external moisture and contaminants decrease exponentially with time. Contaminants profiles are plotted and discussed some possible techniques of contaminants detection. All computations are executed using Computer Algebra, specifically Maple. It is said that the results are important for the food industry and it is suggested some future research lines.
Evaluation of Cleanliness Test Methods for Spacecraft PCB Assemblies

NASA Astrophysics Data System (ADS)

Tegehall, P.-E.; Dunn, B. D.

2006-10-01

Ionic contamination on printed-circuit-board assemblies may cause current leakage and short-circuits. The present cleanliness requirement in ECSS-Q-70-08, "The manual soldering of high-reliability electrical connections", is that the ionic contamination shall be less than 1.56 fl-glcm2 NaCI equivalents. The relevance of the method used for measurement of the ionic contamination level, resistivity of solvent extract, has been questioned. Alternative methods are ion chromatography and measurement of surface insulation resistance, but these methods also have their drawbacks. These methods are first described and their advantages and drawbacks are discussed. This is followed by an experimental evaluation of the three methods. This was done by soldering test vehicles at four manufacturers of space electronics using their ordinary processes for soldering and cleaning printed board assemblies. The experimental evaluation showed that the ionic contamination added by the four assemblers was very small and well below the acceptance criterion in ECSS-Q-70-80. Ion-chromatography analysis showed that most of the ionic contamination on the cleaned assembled boards originated from the hot-oil fusing of the printed circuit boards. Also, the surface insulation resistance was higher on the assembled boards compared to the bare printed circuit boards. Since strongly activated fluxes are normally used when printed circuit boards are hot-oil fused, it is essential that they are thoroughly cleaned in order to achieve low contamination levels on the final printed-board assemblies.
Superconductive microstrip exhibiting negative differential resistivity

DOEpatents

Huebener, R.P.; Gallus, D.E.

1975-10-28

A device capable of exhibiting negative differential electrical resistivity over a range of values of current and voltage is formed by vapor- depositing a thin layer of a material capable of exhibiting superconductivity on an insulating substrate, establishing electrical connections at opposite ends of the deposited strip, and cooling the alloy into its superconducting range. The device will exhibit negative differential resistivity when biased in the current- induced resistive state.
Laboratory Study of Quaternary Sediment Resistivity Related to Groundwater Contamination at Mae-Hia Landfill, Mueang District, Chiang Mai Province

NASA Astrophysics Data System (ADS)

Sichan, N.

2007-12-01

This study was aimed to understand the nature of the resistivity value of the sediment when it is contaminated, in order to use the information solving the obscure interpretation in the field. The pilot laboratory experiments were designed to simulate various degree of contamination and degree of saturation then observe the resulting changes in resistivity. The study was expected to get a better understanding of how various physical parameters effect the resistivity values in term of mathematic function. And also expected to apply those obtained function to a practical quantitatively interpretation. The sediment underlying the Mae-Hia Landfill consists of clay-rich material, with interfingerings of colluvium and sandy alluvium. A systematic study identified four kinds of sediment, sand, clayey sand, sandy clay, and clay. Representative sediment and leachate samples were taken from the field and returned to the laboratory. Both the physical and chemical properties of the sediments and leachate were analyzed to delineate the necessary parameters that could be used in Archie's equation. Sediment samples were mixed with various concentration of leachate solutions. Then the resistivity values were measured at various controlled steps in the saturation degree in a well- calibrated six-electrode model resistivity box. The measured resistivity values for sand, clayey sand, sandy clay when fully and partly saturated were collected, then plotted and fitted to Archie's equation, to obtain a mathematical relationship between bulk resistivity, porosity, saturation degree and resistivity of pore fluid. The results fit well to Archie's equation, and it was possible to determine all the unknown parameters representative of the sediment samples. For sand, clayey sand, sandy clay, and clay, the formation resistivity factors (F) are 2.90, 5.77, 7.85, and 7.85 with the products of cementation factor (m) and the pore geometry factors (a) (in term of -am) are 1.49, -1.63, -1.92, -2.24 and the saturation exponents (n) are 2.06, 2.58, 3.52, and 2.46, respectively. These results were used to reinterpret the existing resistivity data of this area. The result of this reinterpretation is a map showing the quantitative distribution of the contaminant plume in the vicinity of the Mae-Hia Landfill.
SMIF capability at Intel Mask Operation improves yield

NASA Astrophysics Data System (ADS)

Dam, Thuc H.; Pekny, Matt; Millino, Jim; Luu, Gibson; Melwani, Nitesh; Venkatramani, Aparna; Tavassoli, Malahat

2003-08-01

At Intel Mask Operations (IMO), Standard Mechanical Interface (SMIF) processing has been employed to reduce environmental particle contamination from manual handling-related activities. SMIF handling entailed the utilization of automated robotic transfers of photoblanks/reticles between SMIF pods, whereas conventional handling utilized manual pick transfers of masks between SMIF pods with intermediate storage in Toppan compacts. The SMIF-enabling units in IMO's process line included: (1) coater, (2) exposure, (3) developer, (4) dry etcher, and (5) inspection. Each unit is equipped with automated I/O port, environmentally enclosed processing chamber, and SMIF pods. Yield metrics were utilized to demonstrate the effectiveness and advantages of SMIF processing compared to manual processing. The areas focused in this paper were blank resist coating, binary front-end reticle processing and 2nd level PSM reticle processing. Results obtained from the investigation showed yield improvements in these areas.
Computer modeling of dendritic web growth processes and characterization of the material

NASA Technical Reports Server (NTRS)

Seidensticker, R. G.; Kothmann, R. E.; Mchugh, J. P.; Duncan, C. S.; Hopkins, R. H.; Blais, P. D.; Davis, J. R.; Rohatgi, A.

1978-01-01

High area throughput rate will be required for the economical production of silicon dendritic web for solar cells. Web width depends largely on the temperature distribution on the melt surface while growth speed is controlled by the dissipation of the latent heat of fusion. Thermal models were developed to investigate each of these aspects, and were used to engineer the design of laboratory equipment capable of producing crystals over 4 cm wide; growth speeds up to 10 cm/min were achieved. The web crystals were characterized by resistivity, lifetime and etch pit density data as well as by detailed solar cell I-V data. Solar cells ranged in efficiency from about 10 to 14.5% (AM-1) depending on growth conditions. Cells with lower efficiency displayed lowered bulk lifetime believed to be due to surface contamination.
Fecal contamination of drinking water in Kericho District, Western Kenya: role of source and household water handling and hygiene practices.

PubMed

Too, Johana Kiplagat; Kipkemboi Sang, Willy; Ng'ang'a, Zipporah; Ngayo, Musa Otieno

2016-08-01

Inadequate protection of water sources, and poor household hygienic and handling practices have exacerbated fecal water contamination in Kenya. This study evaluated the rate and correlates of thermotolerant coliform (TTC) household water contamination in Kericho District, Western Kenya. Culture and multiplex polymerase chain reaction (PCR) techniques were used to characterize TTCs. The disk diffusion method was used for antibiotic susceptibility profiling of pathogenic Escherichia coli. Out of the 103 households surveyed, 48 (46.6%) had TTC contaminated drinking water (TTC levels of >10 cfu/100 mL). Five of these households were contaminated with pathogenic E. coli, including 40% enteroaggregative E. coli, 40% enterotoxigenic E. coli, and 20% enteropathogenic E. coli. All these pathogenic E. coli strains were multidrug resistant to sulfamethoxazole/trimethoprim, ampicillin, tetracycline and ampicillin/sulbactam. Rural household locality, drinking water hand contact, water storage container cleaning practice, hand washing before water withdrawal, water source total coliforms <10 cfu/100 mL, temperature, and free chlorine levels were associated with TTC contamination of household drinking water. Significant proportions of household drinking water in Kericho District are contaminated with TTCs including with pathogenic multidrug-resistant E. coli. Source and household hygiene and practices contribute significantly to drinking water contamination.
Corrosive resistant heat exchanger

DOEpatents

Richlen, Scott L.

1989-01-01

A corrosive and errosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is conveyed through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium.
Impact of air exposure and surface chemistry on Li-Li 7La 3Zr 2O 12 interfacial resistance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharafi, Asma; Yu, Seungho; Naguib, Michael

Li 7La 3Zr 2O 12 (LLZO) is a promising solid-state electrolyte that could enable solid-state-batteries (SSB) employing metallic Li anodes. For a SSB to be viable, the stability and charge transfer kinetics at the Li–LLZO interface should foster facile plating and stripping of Li. Contrary to these goals, recent studies have reported high Li–LLZO interfacial resistance which was attributed to a contamination layer that forms upon exposure of LLZO to air. This study clarifies the mechanisms and consequences associated with air exposure of LLZO; additionally, strategies to minimize these effects are described. First-principles calculations reveal that LLZO readily reacts withmore » humid air; the most favorable reaction pathway involves protonation of LLZO and formation of Li2CO3. X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy were used to characterize the surface and subsurface chemistry of LLZO as a function of relative humidity and exposure time. Additionally, electrochemical impedance spectroscopy was used to measure the Li–LLZO interfacial resistance as a function of surface contamination. These data indicate that air exposure-induced contamination impacts the interfacial resistance significantly, when exposure time exceeds 24 h. The results of this study provide valuable insight into the sensitivity of LLZO to air and how the effects of air contamination can be reversed.« less

Ambulance vehicles as a source of multidrug-resistant infections: a multicenter study in Assiut City, Egypt

PubMed Central

2018-01-01

Background Ambulances may represent a potential source of infection to patients, patients’ relatives, and paramedical staffs. In this study, we analyzed the extent of bacterial contamination in ambulance vehicles and measured the degree of antimicrobial resistance among isolated pathogens. Materials and methods Twenty-five vehicles were included and 16 sampling points were swabbed in each vehicle. Then the swabs were immediately transferred to the laboratory to identify bacterial contaminants utilizing standard microbiological procedures and API® systems. Antibiotic susceptibility testing and screening for methicillin-resistant staphylococci and extended spectrum β-lactamases (ESBLs)-producing Gram-negative rods were carried out. Results A total of 400 samples were collected, 589 bacteria were isolated and 286 (48.6%) of the isolates were potentially pathogenic. The highest contamination rate with pathogenic bacteria was detected in suction devices (75.8%) and stethoscopes (67.7%). Staphylococci were the most frequently detected microorganisms (n=184) followed by Klebsiella spp. (49), Escherichia coli (40), Citrobacter spp. (7), and Proteus spp. (6). Staphylococci were mostly sensitive to vancomycin, whereas Gram-negative bacteria were sensitive to imipenem. Overall, 46.1% of Staphylococcus aureus were methicillin resistant, whereas 20.4% of the coagulase-negative staphylococci were methicillin resistant. Moreover, 36.7% of Klebsiella spp. and 27.5% of E. coli were ESBL producers. Conclusion Our study provides evidence that ambulances represent a source of prehospital multidrug-resistant infections. PMID:29731647
Investigating antibiotics, antibiotic resistance genes, and microbial contaminants in groundwater in relation to the proximity of urban areas.

PubMed

Szekeres, Edina; Chiriac, Cecilia Maria; Baricz, Andreea; Szőke-Nagy, Tiberiu; Lung, Ildiko; Soran, Maria-Loredana; Rudi, Knut; Dragos, Nicolae; Coman, Cristian

2018-05-01

Groundwater is an essential public and drinking water supply and its protection is a goal for global policies. Here, we investigated the presence and prevalence of antibiotic residues, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and microbial contamination in groundwater environments at various distances from urban areas. Antibiotic concentrations ranged from below detection limit to 917 ng/L, being trimethoprim, macrolide, and sulfonamide the most abundant antibiotic classes. A total of eleven ARGs (aminoglycoside, β-lactam, chloramphenicol, Macrolide-Lincosamide-Streptogramin B - MLSB, sulfonamide, and tetracycline), one antiseptic resistance gene, and two MGEs were detected by qPCR with relative abundances ranging from 6.61 × 10 -7 to 2.30 × 10 -1 copies/16S rRNA gene copies. ARGs and MGEs were widespread in the investigated groundwater environments, with increased abundances not only in urban, but also in remote areas. Distinct bacterial community profiles were observed, with a higher prevalence of Betaproteobacteria and Bacteroidetes in the less-impacted areas, and that of Firmicutes in the contaminated groundwater. The combined characteristics of increased species diversity, distinct phylogenetic composition, and the possible presence of fecal and/or pathogenic bacteria could indicate different types of contamination. Significant correlations between ARGs, MGEs and specific taxa within the groundwater bacterial community were identified, revealing the potential hosts of resistance types. Although no universal marker gene could be determined, a co-selection of int1, qacEΔ1 and sulI genes, a proxy group for anthropogenic pollution, with the tetC, tetO, tetW resistance genes was identified. As the tet group was observed to follow the pattern of environmental contamination for the groundwater samples investigated in this study, our results strongly support the proposal of this group of genes as an environmental tracer of human impact. Overall, the present study investigated several emerging contaminants in groundwater habitats that may be included in monitoring programs to enable further regulatory and protection measures. Copyright © 2018 Elsevier Ltd. All rights reserved.
Characterization of Vancomycin-Resistant Enterococcus faecalis and Enterococcus faecium Isolated from Fresh Produces and Human Fecal Samples.

PubMed

Kim, Min-Chan; Cha, Min-Hyeok; Ryu, Jae-Gee; Woo, Gun-Jo

2017-04-01

Increased enterococcal infections in hospitals and multidrug-resistant and vancomycin-resistant enterococci (VRE) isolated from humans, animals, and food sources raised public health concern on the presence of VRE in multiple sources. We performed a comparative analysis of the antimicrobial resistance and genetics of VRE isolates derived from fresh produce and human fecal samples. Of 389 Enterococcus isolates, 8 fecal and 3 produce isolates were resistant to vancomycin and teicoplanin; all harbored vanA gene. The VRE isolates showed multidrug-resistant properties. The isolates from fresh produce in this study showed to have the common shared characteristics with the isolates from humans by the results of antimicrobial resistance, multilocus sequence typing, and Tn 1546 transposon analysis. Therefore, VRE isolates from fresh produce are likely related to VRE derived from humans. The results suggested that VRE may contaminate vegetables through the environment, and the contaminated vegetables could then act as a vehicle for human infections. Ongoing nationwide surveillance of antibiotic resistance and the promotion of the proper use of antibiotics are necessary.
Tributyltin-resistant bacteria from estuarine and freshwater sediments.

PubMed Central

Wuertz, S; Miller, C E; Pfister, R M; Cooney, J J

1991-01-01

Resistance to tributyltin (TBT) was examined in populations from TBT-polluted sediments and nonpolluted sediments from an estuary and from fresh water as well as in pure cultures isolated from those sediments. The 50% effective concentrations (EC50s) for populations were higher at a TBT-polluted freshwater site than at a site without TBT, suggesting that TBT selected for a TBT-resistant population. In contrast, EC50s were significantly lower for populations from a TBT-contaminated estuarine site than for those from a site without TBT, suggesting that other factors in addition to TBT determine whether populations become resistant. EC50s for populations from TBT-contaminated freshwater sediments were nearly 30 times higher than those for populations from TBT-contaminated estuarine sediments. We defined a TBT-resistant bacterium as one which grows on trypticase soy agar containing 8.4 microM TBT, a concentration which prevented the growth of 90% of the culturable bacteria from these sediments. The toxicity of TBT in laboratory media was influenced markedly by the composition of the medium and whether it was liquid or solid. Ten TBT-resistant isolates from estuarine sediments and 19 from freshwater sediments were identified to the genus level. Two isolates, each a Bacillus sp., may be the first gram-positive bacteria isolated from fresh water in the presence of a high concentration of TBT. There was a high incidence of resistance to heavy metals: metal resistance indices were 0.76 for estuarine isolates and 0.68 for freshwater isolates.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1746939
Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

DOEpatents

Ramirez, Abelardo L.; Cooper, John F.; Daily, William D.

1996-01-01

This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination.
Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

DOEpatents

Ramirez, A.L.; Cooper, J.F.; Daily, W.D.

1996-02-27

This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination. 1 fig.
Implications of Bt traits on mycotoxin contamination in maize: Overview and recent experimental results in southern United States.

PubMed

Abbas, Hamed K; Zablotowicz, Robert M; Weaver, Mark A; Shier, W Thomas; Bruns, H Arnold; Bellaloui, Nacer; Accinelli, Cesare; Abel, Craig A

2013-12-04

Mycotoxin contamination levels in maize kernels are controlled by a complex set of factors including insect pressure, fungal inoculum potential, and environmental conditions that are difficult to predict. Methods are becoming available to control mycotoxin-producing fungi in preharvest crops, including Bt expression, biocontrol, and host plant resistance. Initial reports in the United States and other countries have associated Bt expression with reduced fumonisin, deoxynivalenol, and zearalenone contamination and, to a lesser extent, reduced aflatoxin contamination in harvested maize kernels. However, subsequent field results have been inconsistent, confirming that fumonisin contamination can be reduced by Bt expression, but the effect on aflatoxin is, at present, inconclusive. New maize hybrids have been introduced with increased spectra of insect control and higher levels of Bt expression that may provide important tools for mycotoxin reduction and increased yield due to reduced insect feeding, particularly if used together with biocontrol and host plant resistance.
Characterization of a microbial consortium capable of rapid and simultaneous dechlorination of 1,1,2,2-tetrachloroethane and chlorinated ethane and ethene intermediates

USGS Publications Warehouse

Jones, E.J.P.; Voytek, M.A.; Lorah, M.M.; Kirshtein, J.D.

2006-01-01

A study was carried out to develop a culture of microorganisms for bioaugmentation treatment of chlorinated-ethane contaminated groundwater at sites where dechlorination is incomplete or rates are too slow for effective remedation. Mixed cultures capable of dechlorinating chlorinated ethanes and ethenes were enriched from contaminated wetland sediment at Aberdeen Proving Ground (APG) Maryland. The West Branch Consortium (WBC-2) was capable of degrading 1,1,2,2-tetrachloroethane (TeCA), trichloroethylene (TCE), cis and trans 1,2-dichloroethylene (DCE), 1,1,2-trichloroethane (TCA), 1,2-dichloroethane, and vinyl chloride to nonchlorinated end products ethylene and ethane. WBC-2 dechlorinated TeCA, TCA, and cisDCE rapidly and simultaneously. Methanogens in the consortium were members of the class Methanomicrobia, which includes acetoclastic methanogens. The WBC-2 consortium provides opportunities for the in situ bioremediation of sites contaminated with mixtures of chlorinated ethylenes and ethanes.
[Tracing to the source of staphylococcus aureus isolates from ice cream].

PubMed

Zhang, Yan-Jun; Xu, Dan-Ge; Fang, Ye-Zhen; Gong, Pu; Zhu, Min; Bao, Fang-Zhen

2008-07-01

To investigate the contamination of Staphylococcus aureus isolates in ice cream by phenotypic typing and molecular typing. The Staphylococcus aureus isolates were separated from ice cream, filler, cutter, salves and material. The separated isolates were characterized by drug-resistance, staphylococcal enterotoxin (SEA-E), SE (A-E, G-J) genes and pulsed-field gel electrophoresis (PFGE) types. Two Staphylococcus aureus isolates were separated, one from ice cream, another from cutter. Their characteristics of drug-resistance, staphylococcal enterotoxin (SEA-E), SE (A-E,G-J) genes and PFGE type were the same. The two Staphylococcus aureus isolates were the same clone. The contaminated Staphylococcus aureus isolates could be traced to the contaminated cutters.
Biodegradation of Mixed PAHs by PAH-Degrading Endophytic Bacteria.

PubMed

Zhu, Xuezhu; Ni, Xue; Waigi, Michael Gatheru; Liu, Juan; Sun, Kai; Gao, Yanzheng

2016-08-09

Endophytic bacteria can promote plant growth, induce plant defence mechanisms, and increase plant resistance to organic contaminants. The aims of the present study were to isolate highly PAH-degrading endophytic bacteria from plants growing at PAH-contaminated sites and to evaluate the capabilities of these bacteria to degrade polycyclic aromatic hydrocarbons (PAHs) in vitro, which will be beneficial for re-colonizing target plants and reducing plant PAH residues through the inoculation of plants with endophytic bacteria. Two endophytic bacterial strains P₁ (Stenotrophomonas sp.) and P₃ (Pseudomonas sp.), which degraded more than 90% of phenanthrene (PHE) within 7 days, were isolated from Conyza canadensis and Trifolium pretense L., respectively. Both strains could use naphthalene (NAP), PHE, fluorene (FLR), pyrene (PYR), and benzo(a)pyrene (B(a)P) as the sole sources of carbon and energy. Moreover, these bacteria reduced the contamination of mixed PAHs at high levels after inoculation for 7 days; strain P₁ degraded 98.0% NAP, 83.1% FLR, 87.8% PHE, 14.4% PYR, and 1.6% B(a)P, and strain P₃ degraded 95.3% NAP, 87.9% FLR, 90.4% PHE, 6.9% PYR, and negligible B(a)P. Notably, the biodegradation of PAHs could be promoted through additional carbon and nitrogen nutrients; therein, beef extract was suggested as the optimal co-substrate for the degradation of PAHs by these two strains (99.1% PHE was degraded within 7 days). Compared with strain P₁, strain P₃ has more potential for the use in the removal of PAHs from plant tissues. These results provide a novel perspective in the reduction of plant PAH residues in PAH-contaminated sites through inoculating plants with highly PAH-degrading endophytic bacteria.
Swimmer's itch (image)

MedlinePlus

Swimmer's itch is caused by parasites found in contaminated water. The parasite enters through the skin and a rash appears at the site of entry. In some tropical countries, the parasite found in the contaminated water is capable of producing a severe disease.
Lead-resistant Providencia alcalifaciens strain 2EA bioprecipitates Pb+2 as lead phosphate.

PubMed

Naik, M M; Khanolkar, D; Dubey, S K

2013-02-01

A lead-resistant bacteria isolated from soil contaminated with car battery waste were identified as Providencia alcalifaciens based on biochemical characteristics, FAME profile and 16S rRNA sequencing and designated as strain 2EA. It resists lead nitrate up to 0·0014 mol l(-1) by precipitating soluble lead as insoluble light brown solid. Scanning electron microscopy coupled with energy-dispersive X-ray spectrometric analysis (SEM-EDX) and X-ray diffraction spectroscopy (XRD) revealed extracellular light brown precipitate as lead orthophosphate mineral, that is, Pb(9) (PO(4))(6) catalysed by phosphatase enzyme. This lead-resistant bacterial strain also demonstrated tolerance to high levels of cadmium and mercury along with multiple antibiotic resistance. Providencia alcalifaciens strain 2EA could be used for bioremediation of lead-contaminated environmental sites, as it can efficiently precipitate lead as lead phosphate. © 2012 The Society for Applied Microbiology.
Corrosion sensor for monitoring the service condition of chloride-contaminated cement mortar.

PubMed

Lu, Shuang; Ba, Heng-Jing

2010-01-01

A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (Rp) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (Rs). The results show that the polarization resistance is related to the chloride content and Rs; ln (Rp) is linearly related to the Rs values in mortar without added chloride. The relationships observed between the Rp of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that Rs can indicate the corrosion state of concrete structures.
SugE belongs to the small multidrug resistance (SMR) protein family involved in tributyltin (TBT) biodegradation and bioremediation by alkaliphilic Stenotrophomonas chelatiphaga HS2.

PubMed

Hassan, Hamdy A

2018-03-01

Tributyltin (TBT) used in a variety of industrial processes, subsequent discharge into the environment, its fate, toxicity and human exposure are topics of current concern. TBT degradation by alkaliphilic bacteria may be a key factor in the remediation of TBT in high pH contaminated sites. In this study, Stenotrophomonas chelatiphaga HS2 were isolated and identified from TBT contaminated site in Mediterranean Sea. S. chelatiphaga HS2 has vigor capability to transform TBT into dibutyltin and monobutyltin (DBT and MBT) at pH 9 and 7% NaCl (w/v). A gene was amplified and characterized from strain HS2 as SugE protein belongs to SMR protein family, a reverse transcription polymerase chain reaction analysis confirmed that SugE protein involved in the TBT degradation by HS2 strain. TBT bioremediation was investigated in stimulated TBT contaminated sediment samples (pH 9) using S chelatiphaga HS2 in association with E. coli BL21 (DE3)-pET28a(+)-sugE instead of S chelatiphaga HS2 alone reduced significantly the TBT half-life from 12d to 5d, although no TBT degradation appeared using E. coli BL21 (DE3)-pET28a(+)-sugE alone. This finding indicated that SugE gene increased the rate and degraded amount of TBT and is necessary in enhancing TBT bioremediation. Copyright © 2017 Elsevier B.V. All rights reserved.
Isolation and characterization of yeasts associated with plants growing in heavy-metal- and arsenic-contaminated soils.

PubMed

Ramos-Garza, Juan; Bustamante-Brito, Rafael; Ángeles de Paz, Gabriela; Medina-Canales, Ma Gabriela; Vásquez-Murrieta, María Soledad; Wang, En Tao; Rodríguez-Tovar, Aída Verónica

2016-04-01

Yeasts were quantified and isolated from the rhizospheres of 5 plant species grown at 2 sites of a Mexican region contaminated with arsenic, lead, and other heavy metals. Yeast abundance was about 10(2) CFU/g of soil and 31 isolates were obtained. On the basis of the phylogenetic analysis of 26S rRNA and internal transcribed spacer fragment, 6 species were identified within the following 5 genera: Cryptococcus (80.64%), Rhodotorula (6.45%), Exophiala (6.45%), Trichosporon (3.22%), and Cystobasidium (3.22%). Cryptococcus spp. was the predominant group. Pectinases (51.6%), proteases (51.6%), and xylanases (41.9%) were the enzymes most common, while poor production of siderophores (16.1%) and indole acetic acid (9.67%) was detected. Isolates of Rhodotorula mucilaginosa and Cystobasidium sloffiae could promote plant growth and seed germination in a bioassay using Brassica juncea. Resistance of isolates by arsenic and heavy metals was as follows: As(3+) ≥ 100 mmol/L, As(5+) ≥ 30 mmol/L, Zn(2+) ≥ 2 mmol/L, Pb(2+) ≥ 1.2 mmol/L, and Cu(2+) ≥ 0.5 mmol/L. Strains of Cryptococcus albidus were able to reduce arsenate (As(5+)) into arsenite (As(3+)), but no isolate was capable of oxidizing As(3+). This is the first study on the abundance and identification of rhizosphere yeasts in a heavy-metal- and arsenic-contaminated soil, and of the reduction of arsenate by the species C. albidus.
Panel summary of recommendations

NASA Technical Reports Server (NTRS)

Dunbar, Bonnie J.; Coleman, Martin E.; Mitchell, Kenneth L.

1990-01-01

The following Space Station internal contamination topics were addressed: past flight experience (Skylab and Spacelab missions); present flight activities (Spacelabs and Soviet Space Station Mir); future activities (materials science and life science experiments); Space Station capabilities (PPMS, FMS, ECLSS, and U.S. Laboratory overview); manned systems/crew safety; internal contamination detection; contamination control - stowage and handling; and contamination control - waste gas processing. Space Station design assumptions are discussed. Issues and concerns are discussed as they relate to (1) policy and management, (2) subsystem design, (3) experiment design, and (4) internal contamination detection and control. The recommendations generated are summarized.
Potential bioremediation of mercury-contaminated substrate using filamentous fungi isolated from forest soil.

PubMed

Kurniati, Evi; Arfarita, Novi; Imai, Tsuyoshi; Higuchi, Takaya; Kanno, Ariyo; Yamamoto, Koichi; Sekine, Masahiko

2014-06-01

The use of filamentous fungi in bioremediation of heavy metal contamination has been developed recently. This research aims to observe the capability of filamentous fungi isolated from forest soil for bioremediation of mercury contamination in a substrate. Six fungal strains were selected based on their capability to grow in 25 mg/L Hg(2+)-contaminated potato dextrose agar plates. Fungal strain KRP1 showed the highest ratio of growth diameter, 0.831, thus was chosen for further observation. Identification based on colony and cell morphology carried out by 18S rRNA analysis gave a 98% match to Aspergillus flavus strain KRP1. The fungal characteristics in mercury(II) contamination such as range of optimum pH, optimum temperature and tolerance level were 5.5-7 and 25-35°C and 100 mg/L respectively. The concentration of mercury in the media affected fungal growth during lag phases. The capability of the fungal strain to remove the mercury(II) contaminant was evaluated in 100 mL sterile 10 mg/L Hg(2+)-contaminated potato dextrose broth media in 250 mL Erlenmeyer flasks inoculated with 10(8) spore/mL fungal spore suspension and incubation at 30°C for 7 days. The mercury(II) utilization was observed for flasks shaken in a 130 r/min orbital shaker (shaken) and non-shaken flasks (static) treatments. Flasks containing contaminated media with no fungal spores were also provided as control. All treatments were done in triplicate. The strain was able to remove 97.50% and 98.73% mercury from shaken and static systems respectively. A. flavus strain KRP1 seems to have potential use in bioremediation of aqueous substrates containing mercury(II) through a biosorption mechanism. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.
Culture-dependent and independent studies of microbial diversity in highly copper-contaminated Chilean marine sediments.

PubMed

Besaury, Ludovic; Marty, Florence; Buquet, Sylvaine; Mesnage, Valérie; Muyzer, Gerard; Quillet, Laurent

2013-02-01

Cultivation and molecular-based approaches were used to study microbial diversity in two Chilean marine sediments contaminated with high (835 ppm) and very high concentrations of copper (1,533 ppm). The diversity of cultivable bacteria resistant to copper was studied at oxic and anoxic conditions, focusing on sulfate-, thiosulfate-, and iron-reducing bacteria. For both sediments, the cultivable bacteria isolated at oxic conditions were mostly affiliated to the genus Bacillus, while at anoxic conditions the majority of the cultivable bacteria found were closely related to members of the genera Desulfovibrio, Sphingomonas, and Virgibacillus. Copper resistance was between 100 and 400 ppm, with the exception of a strain affiliated to members of the genus Desulfuromonas, which was resistant up to 1,000 ppm of copper. In parallel, cloning and sequencing of 16S rRNA was performed to study the total bacterial diversity in the sediments. A weak correlation was observed between the isolated strains and the 16S rRNA operational taxonomic units detected. The presence of copper resistance genes (copA, cusA, and pcoA) was tested for all the strains isolated; only copA was detected in a few isolates, suggesting that other copper resistance mechanisms could be used by the bacteria in those highly copper-contaminated sediments.
Selectivity and resistance to poisons of commercial hydrogen sensors

DOE PAGES

Palmisano, V.; Weidner, E.; Boon-Brett, L.; ...

2015-03-20

The resistance of several models of catalytic, workfunction-based metal-oxide-semiconductor and electrochemical hydrogen sensors to chemical contaminants such as SO 2, H 2S, NO 2 and hexamethyldisiloxane (HMDS) has been investigated. These sensor platforms are among the most commonly used for the detection of hydrogen. The evaluation protocols were based on the methods recommended in the ISO 26142:2010 standard. Permanent alteration of the sensor response to the target analyte (H 2) following exposure to potential poisons at the concentrations specified in ISO 26142 was rarely observed. Although a shift in the baseline response was often observed during exposure to the potentialmore » poisons, only in a few cases did this shift persist after removal of the contaminants. Overall, the resistance of the sensors to poisoning was good. However, a change in sensitivity to hydrogen was observed in the electrochemical platform after exposure to NO 2 and for a catalytic sensor during exposure to SO 2. The siloxane resistance test prescribed in ISO 26142, based on exposure to 10 ppm HMDS, may possibly not properly reflect sensor robustness to siloxanes. In conclusion, further evaluation of the resistance of sensors to other Si-based contaminants and other exposure profiles (e.g., concentration, exposure times) is needed.« less
Genetic basis and importance of metal resistant genes in bacteria for bioremediation of contaminated environments with toxic metal pollutants.

PubMed

Das, Surajit; Dash, Hirak R; Chakraborty, Jaya

2016-04-01

Metal pollution is one of the most persistent and complex environmental issues, causing threat to the ecosystem and human health. On exposure to several toxic metals such as arsenic, cadmium, chromium, copper, lead, and mercury, several bacteria has evolved with many metal-resistant genes as a means of their adaptation. These genes can be further exploited for bioremediation of the metal-contaminated environments. Many operon-clustered metal-resistant genes such as cadB, chrA, copAB, pbrA, merA, and NiCoT have been reported in bacterial systems for cadmium, chromium, copper, lead, mercury, and nickel resistance and detoxification, respectively. The field of environmental bioremediation has been ameliorated by exploiting diverse bacterial detoxification genes. Genetic engineering integrated with bioremediation assists in manipulation of bacterial genome which can enhance toxic metal detoxification that is not usually performed by normal bacteria. These techniques include genetic engineering with single genes or operons, pathway construction, and alternations of the sequences of existing genes. However, numerous facets of bacterial novel metal-resistant genes are yet to be explored for application in microbial bioremediation practices. This review describes the role of bacteria and their adaptive mechanisms for toxic metal detoxification and restoration of contaminated sites.

21 CFR 801.410 - Use of impact-resistant lenses in eyeglasses and sunglasses.

Code of Federal Regulations, 2010 CFR

2010-04-01

... potential eye injury, eyeglasses and sunglasses must be fitted with impact-resistant lenses, except in those... shall be capable of withstanding the impact test described in paragraph (d)(2) of this section. (3) Each... resistance and shall be capable of withstanding the impact test described in paragraph (d)(2) of this section...
21 CFR 801.410 - Use of impact-resistant lenses in eyeglasses and sunglasses.

Code of Federal Regulations, 2011 CFR

2011-04-01

... potential eye injury, eyeglasses and sunglasses must be fitted with impact-resistant lenses, except in those... shall be capable of withstanding the impact test described in paragraph (d)(2) of this section. (3) Each... resistance and shall be capable of withstanding the impact test described in paragraph (d)(2) of this section...
21 CFR 801.410 - Use of impact-resistant lenses in eyeglasses and sunglasses.

Code of Federal Regulations, 2013 CFR

2013-04-01

... potential eye injury, eyeglasses and sunglasses must be fitted with impact-resistant lenses, except in those... shall be capable of withstanding the impact test described in paragraph (d)(2) of this section. (3) Each... resistance and shall be capable of withstanding the impact test described in paragraph (d)(2) of this section...
21 CFR 801.410 - Use of impact-resistant lenses in eyeglasses and sunglasses.

Code of Federal Regulations, 2014 CFR

2014-04-01

... potential eye injury, eyeglasses and sunglasses must be fitted with impact-resistant lenses, except in those... shall be capable of withstanding the impact test described in paragraph (d)(2) of this section. (3) Each... resistance and shall be capable of withstanding the impact test described in paragraph (d)(2) of this section...
21 CFR 801.410 - Use of impact-resistant lenses in eyeglasses and sunglasses.

Code of Federal Regulations, 2012 CFR

2012-04-01

... potential eye injury, eyeglasses and sunglasses must be fitted with impact-resistant lenses, except in those... shall be capable of withstanding the impact test described in paragraph (d)(2) of this section. (3) Each... resistance and shall be capable of withstanding the impact test described in paragraph (d)(2) of this section...
Electrical Resistivity Imaging for Long-Term Monitoring of Contaminant Degradation

EPA Science Inventory

The results from this experiment strongly suggest that the resistivity changes seen are the results of the biodegradation of the oil. This conclusion was further supported by the results of the microcosm experiment. These results demonstrate the utility of the resistivity method ...
The theoretical relationship between foliage temperature and canopy resistance in sparse crops

NASA Technical Reports Server (NTRS)

Shuttleworth, W. James; Gurney, Robert J.

1990-01-01

One-dimensional, sparse-crop interaction theory is reformulated to allow calculation of the canopy resistance from measurements of foliage temperature. A submodel is introduced to describe eddy diffusion within the canopy which provides a simple, empirical simulation of the reported behavior obtained from a second-order closure model. The sensitivity of the calculated canopy resistance to the parameters and formulas assumed in the model is investigated. The calculation is shown to exhibit a significant but acceptable sensitivity to extreme changes in canopy aerodynamics, and to changes in the surface resistance of the substrate beneath the canopy at high and intermediate values of leaf area index. In very sparse crops changes in the surface resistance of the substrate are shown to contaminate the calculated canopy resistance, tending to amplify the apparent response to changes in water availability. The theory is developed to allow the use of a measurement of substrate temperature as an option to mitigate this contamination.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehrabadi, Bahareh Alsadat Tavakoli; Dinh, Huyen N.; Bender, Guido

The performance loss and recovery of the fuel cell due to Balance of Plant (BOP) contaminants was identified via a combination of experimental data and a mathematical model. The experiments were designed to study the influence of organic contaminants (e.g. those from BOP materials) on the resistance of the catalyst, ionomer and membrane, and a mathematical model was developed that allowed us to separate these competing resistances from the data collected on an operating fuel cell. For this reason, based on the functional groups, four organic contaminants found in BOP materials, diethylene glycol monoethyl ether (DGMEE), diethylene glycol monoethyl ethermore » acetate (DGMEA), benzyl alcohol (BzOH) and 2,6-diaminotoluene (2,6-DAT) were infused separately to the cathode side of the fuel cell. The cell voltage and high frequency impedance resistance was measured as a function of time. The contaminant feed was then discontinued and voltage recovery was measured. It was determined that compounds with ion exchange properties like 2,6-DAT can cause voltage loss with non-reversible recovery, so this compound was studied in more detail. Finally, the degree of voltage loss increased with an increase in concentration, and/or infusion time, and increased with a decrease in catalyst loadings.« less
Bacterial Contamination of Multi-dose Eye Drops at Ophthalmology Department, University of Gondar, Northwest Ethiopia.

PubMed

Tsegaw, Asegedech; Tsegaw, Asamere; Abula, Tefera; Assefa, Yared

2017-01-01

Ophthalmic solutions used for both diagnostic and therapeutic purposes were found to be contaminated with bacteria pathogens and caused serious ocular infections such as keratitis and endophthalmitis. The objective was to assess the magnitude and pattern of bacterial contamination of multi-dose ophthalmic medications and investigate the drug susceptibility pattern of the isolates in the Department of Ophthalmology at Gondar University Teaching Hospital. A total of 100 ophthalmic medications in-use by patients and eye-care workers have been taken and cultured for potential bacterial contamination in the Microbiology Department after 1 week and >1 week of use. The dropper tip and the residual eye medications were examined for contamination. The contaminating bacteria were identified using a standard procedure and drug susceptibility testing to selected antimicrobial agents was done. Eleven ophthalmic medications were contaminated by different bacterial species with a prevalence of 11%. Multi-use and longer duration of use of eye medications were associated with higher rate of contamination. The contamination level ranges from 0% for antibiotics, 20% for local anesthetics, and 40% for povidone iodine. Among bacteria identified, Staphylococcus aureus and coagulase-negative Staphylococcus species were resistant to methicillin while others were sensitive to the antibiotics tested. The prevalence of contamination was low, but methicillin-resistant Staphylococcus was a potential risk. It is recommended that the Department of Ophthalmology should design set of rules about duration of use and safe handling of ophthalmic medications by the staff and patients.
Assessing pigmented pericarp of maize kernels as possible source of resistance to fusarium ear rot, Fusarium spp. infection and fumonisin accumulation.

PubMed

Venturini, Giovanni; Babazadeh, Laleh; Casati, Paola; Pilu, Roberto; Salomoni, Daiana; Toffolatti, Silvia L

2016-06-16

One of the purposes of maize genetic improvement is the research of genotypes resistant to fusarium ear rot (FER) and fumonisin accumulation. Flavonoids in the pericarp of the kernels are considered particularly able to reduce the fumonisin accumulation (FUM). The aim of this field study was to assess the effect of flavonoids, associated with anti-insect protection and Fusarium verticillioides inoculation, on FER symptoms and fumonisin contamination in maize kernels. Two isogenic hybrids, one having pigmentation in the pericarp (P1-rr) and the other without it (P1-wr), were compared. P1-rr showed lower values of FER symptoms and FUM contamination than P1-wr only if the anti-insect protection and the F. verticillioides inoculations were applied in combination. Fusarium spp. kernel infection was not influenced by the presence of flavonoids in the pericarp. Artificial F. verticillioides inoculation was more effective than anti-insect protection in enhancing the inhibition activity of flavonoids toward FUM contamination. The interactions between FUM contamination levels and FER ratings were better modeled in the pigmented hybrid than in the unpigmented one. The variable role that the pigment played in kernel defense against FER and FUM indicates that flavonoids alone may not be completely effective in the resistance of fumonisin contamination in maize. Copyright © 2016 Elsevier B.V. All rights reserved.
Water Access, Sanitation, and Hygiene Conditions and Health Outcomes among Two Settlement Types in Rural Far North Cameroon

PubMed Central

Gorham, Tyler J.; Yoo, Joshua; Garabed, Rebecca; Mouhaman, Arabi; Lee, Jiyoung

2017-01-01

The Far North region in Cameroon has been more heavily impacted by cholera than any other region over the past decade, but very little has been done to study the drivers of waterborne diseases in the region. We investigated the relationship between water, sanitation, and hygiene (WASH) parameters, microbial and antibiotic resistance (AR) contamination levels in drinking water, and health outcomes using health survey and molecular analysis during June and July of 2014 in two settlement types (agro-pastoralist villages and transhumant pastoralist camps). Quantitative polymerase chain reaction was used to determine fecal contamination sources, enteric pathogens, and antibiotic resistance genes. Ruminant-associated fecal contamination was widespread in both settlement types (81.2%), with human-associated contamination detected in 21.7% of the samples. Salmonella spp. (59.4%) and Shiga toxin-producing E. coli (stx1 44.9% and stx2 31.9%) were detected across all samples. Tetracycline resistance was found only in village samples. A significant difference in diarrheal incidence within the past 28 days among young children was found between camps (31.3%) and villages (0.0%). Our findings suggest that water contamination may play an important role in contributing to gastrointestinal illness, supporting the need for future research and public health intervention to reduce gastrointestinal illness in the area. PMID:28425935
A corrosive resistant heat exchanger

DOEpatents

Richlen, S.L.

1987-08-10

A corrosive and erosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is pumped through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium. 3 figs., 3 tabs.
USING ZERO-VALENT METAL NANOPARTICLES TO REMEDIATE ORGANIC CONTAMINANTS

EPA Science Inventory

The transport of organic contaminants down the soil profile constitutes a serious threat to the quality of ground water. Zero-valent metals are considered innocuous abiotic agents capable of mediating decontamination processes in terrestrial systems. In this investigation, ze...
Resistivity and Induced Polarization Imaging at a Hydrocarbon Contaminated Site in Brazil

NASA Astrophysics Data System (ADS)

Ustra, A.; Elis, V.; Hiodo, F.; Bondioli, A.; Miura, G.

2012-12-01

An area contaminated by accidental BTEX spills was investigated with resistivity and induced polarization methods. The main objective in this study was to relate the geophysical signature of the area with zones that were possibly undergoing microbial degradation of the contaminants. The spills took place over a decade ago; however, the exact location of these spills is unknown, as well as the amount of contaminant that was released into the subsurface. DC-resistivity identified a high contrast between the background (rho up to 2000 ohm.m) and a relatively conductive zone (rho < 100 ohm.m), where high chargeabilities were also measured (m > 30 mV/V). Normalized chargeability is enhanced in this anomaly zone (mn > 0.1). Soil samples collected in the area were submitted to direct bacterial count, clay content estimation, X-ray diffraction and SEM analysis. The electrical properties of each samples was also measured. The samples collected from the "background" (high resistivity zone) presented total bacterial amounts much smaller (dozens of colony forming units) than the samples from the conductive zone (millions of colony forming units). This observation could lead us to interpret that the zone of higher bacteria amount is undergoing biodegradation that would explain the increased conductivity at that portion of the subsurface. However, the geophysical properties observed at this zone could also be related to the clay content distribution throughout the surveyed area (concentrations up to 30%). Moreover, despite the fact that more microbes were found in the area, SEM images did not find any biodegradation typical feature of the grains, which are for example, mineral corrosion and dissolution or even biomineralization. This study is still undergoing and we are searching for more evidence of biodegradation in the samples. This study shows the limitation of the use of geophysical methods to access contaminant presence and/or biodegradation zones when the exact location of the contamination is unknown.
Contamination sources, serogroups, biofilm-forming ability and biocide resistance of Listeria monocytogenes persistent in tilapia-processing facilities.

PubMed

Vázquez-Sánchez, Daniel; Galvão, Juliana Antunes; Oetterer, Marília

2017-11-01

The major contamination sources, serogroups, biofilm-forming ability and biocide resistance of Listeria monocytogenes persistent in tilapia-processing facilities were assessed. Twenty-five processing-control points were examined twice in two factories, including whole tilapias, frozen fillets, water and food-contact surfaces. L. monocytogenes were detected in 4 and 20% of points of Factory A and B respectively, but at low concentrations. Contamination was due to inadequate handling of tilapias in the slaughter room of Factory A and to the application of ineffective sanitizing procedures in Factory B. Seven strains were characterized by RAPD-PCR using primers HLWL85, OPM-01 and DAF4. Genotypic similarity allowed tracing the contamination source of tilapia fillets in Factory B and detecting a prevalent strain in Brazilian tilapia-processing facilities. The serogroup II (including the serotype 1/2c) was the most frequently found, followed by serogroup I (1/2a) and III (1/2b), whereas the serotype 4b was not detected. All strains showed high biofilm-forming ability on stainless steel and polystyrene, but biofilm formation was positively correlated with the type of origin surface. Biofilms were highly resistant to peracetic acid and sodium hypochlorite, being required doses higher than those recommended by manufacturers to be eradicated. Peracetic acid was more effective than sodium hypochlorite, but the use of disinfectants with similar mechanisms of action increases the risk of cross-resistance. Case-by-case approaches are thus recommended to determine the sources and degree of contamination present in each factory, which would allow applying precise responses to control the persistence of bacterial pathogens such as L. monocytogenes .
Rushing, distraction, walking on contaminated floors and risk of slipping in limited-service restaurants: a case--crossover study.

PubMed

Verma, Santosh K; Lombardi, David A; Chang, Wen Ruey; Courtney, Theodore K; Huang, Yueng-Hsiang; Brennan, Melanye J; Mittleman, Murray A; Ware, James H; Perry, Melissa J

2011-08-01

This nested case-crossover study examined the association between rushing, distraction and walking on a contaminated floor and the rate of slipping, and whether the effects varied according to weekly hours worked, job tenure and use of slip-resistant shoes. At baseline, workers from 30 limited-service restaurants in the USA reported average work hours, average weekly duration of exposure to each transient risk factor and job tenure at the current location. Use of slip-resistant shoes was determined. During the following 12 weeks, participants reported weekly their slip experience and exposures to the three transient exposures at the time of slipping. The case-crossover design was used to estimate the rate ratios using the Mantel-Haenszel estimator for person-time data. Among 396 participants providing baseline information, 210 reported one or more slips with a total of 989 slips. Rate of slipping was 2.9 times higher when rushing as compared to working at a normal pace (95% CI 2.5 to 3.3). Rate of slipping was also significantly increased by distraction (rate ratio (RR) 1.7, 95% CI 1.5 to 2.0) and walking on a contaminated floor (RR 14.6, 95% CI 12.6 to 17.0). Use of slip-resistant shoes decreased the effects of rushing and walking on a contaminated floor. Rate ratios for all three transient factors decreased monotonically as job tenure increased. The results suggest the importance of these transient risk factors, particularly floor contamination, on rate of slipping in limited-service restaurant workers. Stable characteristics, such as slip-resistant shoes, reduced the effects of transient exposures.
Bacteria associated with oak and ash on a TCE-contaminated site: characterization of isolates with potential to avoid evapotranspiration of TCE.

PubMed

Weyens, Nele; Taghavi, Safiyh; Barac, Tanja; van der Lelie, Daniel; Boulet, Jana; Artois, Tom; Carleer, Robert; Vangronsveld, Jaco

2009-11-01

Along transects under a mixed woodland of English Oak (Quercus robur) and Common Ash (Fraxinus excelsior) growing on a trichloroethylene (TCE)-contaminated groundwater plume, sharp decreases in TCE concentrations were observed, while transects outside the planted area did not show this remarkable decrease. This suggested a possibly active role of the trees and their associated bacteria in the remediation process. Therefore, the cultivable bacterial communities associated with both tree species growing on this TCE-contaminated groundwater plume were investigated in order to assess the possibilities and practical aspects of using these common native tree species and their associated bacteria for phytoremediation. In this study, only the cultivable bacteria were characterized because the final aim was to isolate TCE-degrading, heavy metal resistant bacteria that might be used as traceable inocula to enhance bioremediation. Cultivable bacteria isolated from bulk soil, rhizosphere, root, stem, and leaf were genotypically characterized by amplified rDNA restriction analysis (ARDRA) of their 16S rRNA gene and identified by 16S rRNA gene sequencing. Bacteria that displayed distinct ARDRA patterns were screened for heavy metal resistance, as well as TCE tolerance and degradation, as preparation for possible future in situ inoculation experiments. Furthermore, in situ evapotranspiration measurements were performed to investigate if the degradation capacity of the associated bacteria is enough to prevent TCE evapotranspiration to the air. Between both tree species, the associated populations of cultivable bacteria clearly differed in composition. In English Oak, more species-specific, most likely obligate endophytes were found. The majority of the isolated bacteria showed increased tolerance to TCE, and TCE degradation capacity was observed in some of the strains. However, in situ evapotranspiration measurements revealed that a significant amount of TCE and its metabolites was evaporating through the leaves to the atmosphere. The characterization of the isolates obtained in this study shows that the bacterial community associated with Oak and Ash on a TCE-contaminated site, was strongly enriched with TCE-tolerant strains. However, this was not sufficient to degrade all TCE before it reaches the leaves. A possible strategy to overcome this evapotranspiration to the atmosphere is to enrich the plant-associated TCE-degrading bacteria by in situ inoculation with endophytic strains capable of degrading TCE.
Bacteria associated with oak and ash on a TCE-contaminated site: Characterization of isolates with potential to avoid evapotranspiration of TCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weyens, N.; van der Lelie, D.; Taghavi, S.

2009-11-01

Along transects under a mixed woodland of English Oak (Quercus robur) and Common Ash (Fraxinus excelsior) growing on a trichloroethylene (TCE)-contaminated groundwater plume, sharp decreases in TCE concentrations were observed, while transects outside the planted area did not show this remarkable decrease. This suggested a possibly active role of the trees and their associated bacteria in the remediation process. Therefore, the cultivable bacterial communities associated with both tree species growing on this TCE-contaminated groundwater plume were investigated in order to assess the possibilities and practical aspects of using these common native tree species and their associated bacteria for phytoremediation. Inmore » this study, only the cultivable bacteria were characterized because the final aim was to isolate TCE-degrading, heavy metal resistant bacteria that might be used as traceable inocula to enhance bioremediation. Cultivable bacteria isolated from bulk soil, rhizosphere, root, stem, and leaf were genotypically characterized by amplified rDNA restriction analysis (ARDRA) of their 16S rRNA gene and identified by 16S rRNA gene sequencing. Bacteria that displayed distinct ARDRA patterns were screened for heavy metal resistance, as well as TCE tolerance and degradation, as preparation for possible future in situ inoculation experiments. Furthermore, in situ evapotranspiration measurements were performed to investigate if the degradation capacity of the associated bacteria is enough to prevent TCE evapotranspiration to the air. Between both tree species, the associated populations of cultivable bacteria clearly differed in composition. In English Oak, more species-specific, most likely obligate endophytes were found. The majority of the isolated bacteria showed increased tolerance to TCE, and TCE degradation capacity was observed in some of the strains. However, in situ evapotranspiration measurements revealed that a significant amount of TCE and its metabolites was evaporating through the leaves to the atmosphere. The characterization of the isolates obtained in this study shows that the bacterial community associated with Oak and Ash on a TCE-contaminated site, was strongly enriched with TCE-tolerant strains. However, this was not sufficient to degrade all TCE before it reaches the leaves. A possible strategy to overcome this evapotranspiration to the atmosphere is to enrich the plant-associated TCE-degrading bacteria by in situ inoculation with endophytic strains capable of degrading TCE.« less
Resistance of Pseudomonas aeruginosa to liquid disinfectants on contaminated surfaces before formation of biofilms.

PubMed

Sagripanti, J L; Bonifacino, A

2000-01-01

A comparison was made of the effectiveness of popular disinfectants (Cavicide, Cidexplus, Clorox, Exspor, Lysol, Renalin, and Wavicide) under conditions prescribed for disinfection in the respective product labels on Pseudomonas aeruginosa either in suspension or deposited onto surfaces of metallic or polymeric plastic devices. The testing also included 7 nonformulated germicidal agents (glutaraldehyde, formaldehyde, peracetic acid, hydrogen peroxide, sodium hypochlorite, phenol, and cupric ascorbate) commonly used in disinfection and decontamination. Results showed that P. aeruginosa is on average 300-fold more resistant when present on contaminated surfaces than in suspension. This increase in resistance agrees with results reported in studies of biofilms, but unexpectedly, it precedes biofilm formation. The surface to which bacteria are attached can influence the effectiveness of disinfectants. Viable bacteria attached to devices may require dislodging through more than a one-step method for detection. The data, obtained with a sensitive and quantitative test, suggest that disinfectants are less effective on contaminated surfaces than generally acknowledged.
Space shuttle prototype check valve development

NASA Technical Reports Server (NTRS)

Tellier, G. F.

1976-01-01

Contaminant-resistant seal designs and a dynamically stable prototype check valve for the orbital maneuvering and reaction control helium pressurization systems of the space shuttle were developed. Polymer and carbide seal models were designed and tested. Perfluoroelastomers compatible with N2O4 and N2H4 types were evaluated and compared with Teflon in flat and captive seal models. Low load sealing and contamination resistance tests demonstrated cutter seal superiority over polymer seals. Ceramic and carbide materials were evaluated for N2O4 service using exposure to RFNA as a worst case screen; chemically vapor deposited tungsten carbide was shown to be impervious to the acid after 6 months immersion. A unique carbide shell poppet/cutter seat check valve was designed and tested to demonstrate low cracking pressure ( 2.0 psid), dynamic stability under all test bench flow conditions, contamination resistance (0.001 inch CRES wires cut with 1.5 pound seat load) and long life of 100,000 cycles (leakage 1.0 scc/hr helium from 0.1 to 400 psig).

COUPLED FREE AND DISSOLVED PHASE TRANSPORT: NEW SIMULATION CAPABILITIES AND PARAMETER INVERSION

EPA Science Inventory

The vadose zone free-phase simulation capabilities of the US EPA Hydrocarbon Spill Screening Model (HSSM)have been linked with the 3-D multi-species dissolved-phase contaminant transport simulator MT3DMS.
X-ray position detector and implementation in a mirror pointing servo system

DOEpatents

Rabedeau, Thomas A.; Van Campen, Douglas G.; Stefan, Peter M.

2016-04-05

An X-ray beam position and stability detector is provided having a first metal blade collinear with a second metal blade, where an edge of the first metal blade is opposite an edge of the second metal blade, where the first metal blade edge and the second metal blade edge are disposed along a centerline with respect to each other, where the metal blades are capable of photoelectron emission when exposed to an x-ray beam, a metal coating on the metal blades that is capable of enhancing the photoelectron emission, or suppressing energy-resonant contaminants, or enhancing the photoelectron emission and suppressing energy-resonant contaminants, a background shielding element having an electrode capable of suppressing photoelectron emission from spurious x-rays not contained in an x-ray beam of interest, and a photoelectron emission detector having an amplifier capable of detecting the photoelectron emission as a current signal.
Sediment Toxicity Identification Evaluations (TIEs): Manipulating Bioavailability to Whole Organisms to Identify Environmental Toxins

EPA Science Inventory

Toxicity tests are a common method for determining whether sediment contaminants represent an environmental risk. Toxicity tests indicate if contaminants in sediments are bioavailable and capable of causing adverse biological effects to whole aquatic organisms. Several environmen...
Surface decontamination compositions and methods

DOEpatents

Wright,; Karen, E [Idaho Falls, ID; Cooper, David C [Idaho Falls, ID; Peterman, Dean R [Idaho Falls, ID; Demmer, Ricky L [Idaho Falls, ID; Tripp, Julia L [Pocatello, ID; Hull, Laurence C [Idaho Falls, ID

2011-03-29

Clay-based compositions capable of absorbing contaminants from surfaces or objects having surface faces may be applied to a surface and later removed, the removed clay-based compositions absorbing at least a portion of the contaminant from the surface or object to which it was applied.
Environmental Remediation

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2017-04-11

At Pacific Northwest National Laboratory, we are a leader in subsurface science and remediation. We use our expertise in these areas to characterize subsurface contaminants and assess contaminant transport. We're also using our capabilities to restore the Hanford Site in southeastern Washington State to a safe, clean environment.
Occurrence of antimicrobial-resistant salmonella species in raw and ready to eat turkey meat products from retail outlets in the midwestern United States.

PubMed

Khaitsa, Margaret L; Kegode, Redempta B; Doetkott, Dawn K

2007-01-01

To investigate occurrence of Salmonella in raw and ready to eat (RTE) turkey from retail outlets, determine factors associated with its occurrence and antimicrobial-resistance patterns. A total of 959 turkey products (raw, n = 345; and RTE, n = 614) were purchased in 3 months from four stores in one city in the midwestern United States. Chi-square and logistic regression analyses were used to test for associations of microbial contamination with product type and brand, expiration date, sampling time, and retail store. Antimicrobial resistance of Salmonellae was determined using a National Antimicrobial Resistance Monitoring System (NARMS) panel of antimicrobials. Overall, 2.2% (21/959) of the samples (4.1% [14/345] raw and 1.1% [7/614] RTE) were contaminated with Salmonella. A significant difference in Salmonella occurrence (p < 0.05), between meat type (raw vs. RTE; OR = 4.2, 95% CI = 1.6, 10.8); and sampling month (p < 0.05) was reported, but not between retail stores and product brands. Salmonellae belonged to 6 serotypes: Hadar, Heidelberg, Typhimurium var. Copenhagen, Newport, Saintpaul, and Agona. Salmonellae from raw turkey exhibited higher antimicrobial resistance (53%) compared to those from RTE products (33%). Multidrug resistance was exhibited by 62% of Salmonellae (86% RTE, 50% raw meats). CONCLUSION AND CLINICAL APPLICATIONS: Turkey (both raw and RTE) may occasionally be contaminated with antimicrobial-resistant Salmonellae whose occurrence was influenced by sampling month and meat type. Continued surveillance of Salmonella occurrence in meat products, in particular RTE ones, is warranted in order to ensure a safe food supply.
Small scale monitoring of a bioremediation barrier using miniature electrical resistivity tomography

NASA Astrophysics Data System (ADS)

Sentenac, Philippe; Hogson, Tom; Keenan, Helen; Kulessa, Bernd

2015-04-01

The aim of this study was to assess, in the laboratory, the efficiency of a barrier of oxygen release compound (ORC) to block and divert a diesel plume migration in a scaled aquifer model using miniature electrical resistivity tomography (ERT) as the monitoring system. Two plumes of contaminant (diesel) were injected in a soil model made of local sand and clay. The diesel plumes migration was imaged and monitored using a miniature resistivity array system that has proved to be accurate in soil resistivity variations in small-scaled models of soil. ERT results reflected the lateral spreading and diversion of the diesel plumes in the unsaturated zone. One of the contaminant plumes was partially blocked by the ORC barrier and a diversion and reorganisation of the diesel in the soil matrix was observed. The technique of time-lapse ERT imaging showed that a dense non-aqueous phase liquid (DNAPL) contaminant like diesel can be monitored through a bioremediation barrier and the technique is well suited to monitor the efficiency of the barrier. Therefore, miniature ERT as a small-scale modelling tool could complement conventional techniques, which require more expensive and intrusive site investigation prior to remediation.
Monitoring of In-Situ Remediation By Time Lapse 3D Geo-Electric Measurements

NASA Astrophysics Data System (ADS)

Kanli, A. I.; Tildy, P.; Neducza, B.; Nagy, P.; Hegymegi, C.

2017-12-01

Injection of chemical oxidant solution to degrade the subsurface contaminants can be used for hydrocarbon contamination remediation. In this study, we developed a non-destructive measurement strategy to monitor oxidative in-situ remediation processes. The difficulties of the presented study originate from the small volume of conductive solution that can be used due to environmental considerations. Due to the effect of conductive groundwater and the high clay content of the targeted layer and the small volume of conductive solution that can be used due to environmental considerations, a site specific synthetic modelling is necessary for measurement design involving the results of preliminary 2D ERT measurements, electrical conductivity measurements of different active agents and expected resistivity changes calculated by soil resistivity modelling. Because of chemical biodegradation, the results of soil resistivity modelling have suggested that the reagent have complex effects on contaminated soils. As a result the plume of resistivity changes caused by the injected agent was determined showing strong fracturing effect because of the high pressure of injection. 3D time-lapse geo-electric measurements were proven to provide a usable monitoring tool for in-situ remediation as a result of our sophisticated tests and synthetic modelling.
Development of Canavalia ensiformis in soil contaminated with diesel oil.

PubMed

Balliana, A G; Moura, B B; Inckot, R C; Bona, C

2017-01-01

Hydrocarbons are the main components of diesel oil and are toxic for the majority of plants. A few plant species, known as phytoremediators, are tolerant of hydrocarbons and can survive the stressful conditions of soils contaminated with diesel oil. Canavalia ensiformis, a plant species that is well distributed throughout the tropics, possesses advantageous features for a potential resistance to soil contamination, such as fast growth and a deep root system. Thus, the aim of the present study was to evaluate the tolerance of C. ensiformis when it was exposed to soil contaminated with diesel oil. Seedlings were subjected to two treatments: contaminated soil (CS) (95 ml/kg of diesel oil) and non-contaminated soil (NCS) for a period of 30 days; its growth, morphology, anatomy, and physiology were analyzed. Despite the high level of toxicity, some individuals were able to survive in CS. These plants had root apical meristems with high levels of mitosis and were able to issue new roots with more developed aerenchyma tissue. Because the surviving plants presented no marks of cellular damage on the organs formed (root and leaves) during the experiment, the species capacity of growth on CS was confirmed. Although, long-term field experiments, applying different contaminant concentrations, should be considered to infer about the species resistance and use as phytoremediator.
Oil spill effects on macrofaunal communities and bioturbation of pristine marine sediments (Caleta Valdés, Patagonia, Argentina): experimental evidence of low resistance capacities of benthic systems without history of pollution.

PubMed

Ferrando, Agustina; Gonzalez, Emilia; Franco, Marcos; Commendatore, Marta; Nievas, Marina; Militon, Cécile; Stora, Georges; Gilbert, Franck; Esteves, José Luis; Cuny, Philippe

2015-10-01

The Patagonian coast is characterized by the existence of pristine ecosystems which may be particularly sensitive to oil contamination. In this study, a simulated oil spill at acute and chronic input levels was carried out to assess the effects of contamination on the macrobenthic community structure and the bioturbation activity of sediments sampled in Caleta Valdés creek. Superficial sediments were either noncontaminated or contaminated by Escalante crude oil and incubated in the laboratory for 30 days. Oil contamination induced adverse effects on macrobenthic community at both concentrations with, for the highest concentration, a marked decrease of approximately 40 and 55 % of density and specific richness, respectively. Besides the disappearance of sensitive species, some other species like Oligochaeta sp. 1, Paranebalia sp., and Ostracoda sp. 2 species have a higher resistance to oil contamination. Sediment reworking activity was also affected by oil addition. At the highest level of contamination, nearly no activity was observed due to the high mortality of macroorganisms. The results strongly suggest that an oil spill in this protected marine area with no previous history of contamination would have a deep impact on the non-adapted macrobenthic community.
The role of the surface environment in healthcare-associated infections.

PubMed

Weber, David J; Anderson, Deverick; Rutala, William A

2013-08-01

This article reviews the evidence demonstrating the importance of contamination of hospital surfaces in the transmission of healthcare-associated pathogens and interventions scientifically demonstrated to reduce the levels of microbial contamination and decrease healthcare-associated infections. The contaminated surface environment in hospitals plays an important role in the transmission of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), Clostridium difficile, Acinetobacter spp., and norovirus. Improved surface cleaning and disinfection can reduce transmission of these pathogens. 'No-touch' methods of room disinfection (i.e., devices which produce ultraviolet light or hydrogen peroxide) and 'self-disinfecting' surfaces (e.g., copper) also show promise to decrease contamination and reduce healthcare-associated infections. Hospital surfaces are frequently contaminated with important healthcare-associated pathogens. Contact with the contaminated environment by healthcare personnel is equally as likely as direct contact with a patient to lead to contamination of the healthcare provider's hands or gloves that may result in patient-to-patient transmission of nosocomial pathogens. Admission to a room previously occupied by a patient with MRSA, VRE, Acinetobacter, or C. difficile increases the risk for the subsequent patient admitted to the room to acquire the pathogen. Improved cleaning and disinfection of room surfaces decreases the risk of healthcare-associated infections.
Potential of siderophore-producing bacteria for improving heavy metal phytoextraction.

PubMed

Rajkumar, Mani; Ae, Noriharu; Prasad, Majeti Narasimha Vara; Freitas, Helena

2010-03-01

Phytoremediation holds promise for in situ treatment of heavy metal contaminated soils. Recently, the benefits of combining siderophore-producing bacteria (SPB) with plants for metal removal from contaminated soils have been demonstrated. Metal-resistant SPB play an important role in the successful survival and growth of plants in contaminated soils by alleviating the metal toxicity and supplying the plant with nutrients, particularly iron. Furthermore, bacterial siderophores are able to bind metals other than iron and thus enhance their bioavailability in the rhizosphere of plants. Overall, an increase in plant growth and metal uptake will further enhance the effectiveness of phytoremediation processes. Here, we highlight the diversity and ecology of metal resistant SPB and discuss their potential role in phytoremediation of heavy metals.
Campylobacter in Broiler Chicken and Broiler Meat in Sri Lanka: Influence of Semi-Automated vs. Wet Market Processing on Campylobacter Contamination of Broiler Neck Skin Samples.

PubMed

Kottawatta, Kottawattage S A; Van Bergen, Marcel A P; Abeynayake, Preeni; Wagenaar, Jaap A; Veldman, Kees T; Kalupahana, Ruwani S

2017-11-29

Broiler meat can become contaminated with Campylobacter of intestinal origin during processing. The present study aimed to identify the prevalence of Campylobacter in broiler flocks and meat contamination at retail shops, and determine the influence of semi-automated and wet market processing on Campylobacter contamination of neck skin samples. Samples were collected from semi-automated plants ( n = 102) and wet markets ( n = 25). From each batch of broilers, pooled caecal samples and neck skin samples were tested for Campylobacter . Broiler meat purchased from retail outlets ( n = 37) was also tested. The prevalence of Campylobacter colonized broiler flocks was 67%. The contamination of meat at retail was 59%. Both semi-automated and wet market processing resulted to contaminate the broiler neck skins to the levels of 27.4% and 48%, respectively. When Campylobacter -free broiler flocks were processed in semi-automated facilities 15% (5/33) of neck skin samples became contaminated by the end of processing whereas 25% (2/8) became contaminated after wet market processing. Characterization of isolates revealed a higher proportion of C. coli compared to C. jejuni . Higher proportions of isolates were resistant to important antimicrobials. This study shows the importance of Campylobacter in poultry industry in Sri Lanka and the need for controlling antimicrobial resistance.
Campylobacter in Broiler Chicken and Broiler Meat in Sri Lanka: Influence of Semi-Automated vs. Wet Market Processing on Campylobacter Contamination of Broiler Neck Skin Samples

PubMed Central

Kottawatta, Kottawattage S. A.; Van Bergen, Marcel A. P.; Abeynayake, Preeni; Wagenaar, Jaap A.; Veldman, Kees T.; Kalupahana, Ruwani S.

2017-01-01

Broiler meat can become contaminated with Campylobacter of intestinal origin during processing. The present study aimed to identify the prevalence of Campylobacter in broiler flocks and meat contamination at retail shops, and determine the influence of semi-automated and wet market processing on Campylobacter contamination of neck skin samples. Samples were collected from semi-automated plants (n = 102) and wet markets (n = 25). From each batch of broilers, pooled caecal samples and neck skin samples were tested for Campylobacter. Broiler meat purchased from retail outlets (n = 37) was also tested. The prevalence of Campylobacter colonized broiler flocks was 67%. The contamination of meat at retail was 59%. Both semi-automated and wet market processing resulted to contaminate the broiler neck skins to the levels of 27.4% and 48%, respectively. When Campylobacter-free broiler flocks were processed in semi-automated facilities 15% (5/33) of neck skin samples became contaminated by the end of processing whereas 25% (2/8) became contaminated after wet market processing. Characterization of isolates revealed a higher proportion of C. coli compared to C. jejuni. Higher proportions of isolates were resistant to important antimicrobials. This study shows the importance of Campylobacter in poultry industry in Sri Lanka and the need for controlling antimicrobial resistance. PMID:29186018
FECAL SOURCE TRACKING BY ANTIBIOTIC RESISTANCE ANALYSIS ON A WATERSHED EXHIBITING LOW RESISTANCE

EPA Science Inventory

The ongoing development of microbial source tracking has made it possible to identify contamination sources with varying accuracy, depending on the method used. The purpose of this study was done to test the efficiency of the antibiotic resistance analysis (ARA) method under low ...
Factors affecting thermal resistance of Salmonella enterica serovar enteritidis ODA 99-30581-13 in shell egg contents and use of heat-ozone combinations for egg pasteurization.

PubMed

Perry, Jennifer J; Yousef, Ahmed E

2013-02-01

Infection of laying hens with Salmonella enterica serovar Enteritidis leads to deposition of the pathogen into the albumen or yolk of forming eggs. Heat treatment can inactivate internalized Salmonella Enteritidis in shell eggs, but factors such as the nature and location of contamination may influence the efficacy of thermal treatments. In the current research, natural contamination was mimicked by introducing small inocula of Salmonella Enteritidis into different locations of shell eggs and incubating inoculated eggs. These pathogen-containing eggs were heated at 57°C for 40 min, and temperature within eggs was monitored at the locations of inocula. Comparison of inactivation at equivalent internal temperatures revealed similar levels of lethality regardless of inoculum location. Refrigeration between incubation and heat treatment did not increase thermal resistance of cells in albumen but decreased cell inactivation in yolk. Sequential application of heat and gaseous ozone allows for the development of a process capable of decontaminating shell eggs with minimal thermal treatment and impact on egg quality. Inoculated eggs were subjected to (i) an immersion heating process similar to that used in commercial pasteurization or (ii) immersion heating, at reduced duration, followed by vacuum (50.8 kPa) and treatment with ozone gas (maximum 160 g/m(3)) under pressure (∼187.5 kPa). All treatments tested produced greater than 5-log inactivation, which is required for "pasteurization" processes. Differences were observed in the visual quality of eggs depending on treatment parameters. Application of ozone subsequent to heating allows for a significant reduction in heating time without decreasing process lethality.
A meta-analysis of the rates of Staphylococcus aureus and methicillin-resistant S aureus contamination on the surfaces of environmental objects that health care workers frequently touch.

PubMed

Lin, Dongxin; Ou, Qianting; Lin, Jialing; Peng, Yang; Yao, Zhenjiang

2017-04-01

Health care workers may potentially spread Staphylococcus aureus and methicillin-resistant S aureus (MRSA) to patients by contaminated high-touch items. We aimed to determine the pooled rates of S aureus and MRSA contamination and influencing factors. A literature search of the PubMed, ScienceDirect, Embase, Ovid, and Scopus databases was performed. Pooled contamination rates were determined using random effect models. Subgroup and meta-regression analyses were conducted to identify factors potentially influencing the rates of S aureus and MRSA contamination. Sensitivity and publication bias analyses were performed. Thirty-eight studies were included in the meta-analysis. The pooled contamination rates were 15.0% (95% confidence interval [CI], 9.8%-21.1%) for S aureus and 5.0% (95% CI, 2.7%-7.7%) for MRSA. The subgroup analyses indicated that the pooled rate of S aureus contamination was significantly higher for studies conducted in South America, in developing countries, and during 2010-2015. The pooled rate of MRSA contamination was significantly higher for studies conducted in Africa. The meta-regression analysis suggested that the pooled rate of S aureus contamination was lower for studies conducted in developed countries (odds ratio, 0.664; 95% CI, 0.509-0.867; P = .004). No bias was found in the publication of the rates of S aureus and MRSA contamination. S aureus and MRSA contamination statuses of high-touch items are worrisome and should be paid greater attention. Developing country status was a risk factor for S aureus contamination. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Prospects for Fungal Bioremediation of Acidic Radioactive Waste Sites: Characterization and Genome Sequence of Rhodotorula taiwanensis MD1149.

PubMed

Tkavc, Rok; Matrosova, Vera Y; Grichenko, Olga E; Gostinčar, Cene; Volpe, Robert P; Klimenkova, Polina; Gaidamakova, Elena K; Zhou, Carol E; Stewart, Benjamin J; Lyman, Mathew G; Malfatti, Stephanie A; Rubinfeld, Bonnee; Courtot, Melanie; Singh, Jatinder; Dalgard, Clifton L; Hamilton, Theron; Frey, Kenneth G; Gunde-Cimerman, Nina; Dugan, Lawrence; Daly, Michael J

2017-01-01

Highly concentrated radionuclide waste produced during the Cold War era is stored at US Department of Energy (DOE) production sites. This radioactive waste was often highly acidic and mixed with heavy metals, and has been leaking into the environment since the 1950s. Because of the danger and expense of cleanup of such radioactive sites by physicochemical processes, in situ bioremediation methods are being developed for cleanup of contaminated ground and groundwater. To date, the most developed microbial treatment proposed for high-level radioactive sites employs the radiation-resistant bacterium Deinococcus radiodurans . However, the use of Deinococcus spp. and other bacteria is limited by their sensitivity to low pH. We report the characterization of 27 diverse environmental yeasts for their resistance to ionizing radiation (chronic and acute), heavy metals, pH minima, temperature maxima and optima, and their ability to form biofilms. Remarkably, many yeasts are extremely resistant to ionizing radiation and heavy metals. They also excrete carboxylic acids and are exceptionally tolerant to low pH. A special focus is placed on Rhodotorula taiwanensis MD1149, which was the most resistant to acid and gamma radiation. MD1149 is capable of growing under 66 Gy/h at pH 2.3 and in the presence of high concentrations of mercury and chromium compounds, and forming biofilms under high-level chronic radiation and low pH. We present the whole genome sequence and annotation of R. taiwanensis strain MD1149, with a comparison to other Rhodotorula species. This survey elevates yeasts to the frontier of biology's most radiation-resistant representatives, presenting a strong rationale for a role of fungi in bioremediation of acidic radioactive waste sites.
Prospects for Fungal Bioremediation of Acidic Radioactive Waste Sites: Characterization and Genome Sequence of Rhodotorula taiwanensis MD1149

PubMed Central

Tkavc, Rok; Matrosova, Vera Y.; Grichenko, Olga E.; Gostinčar, Cene; Volpe, Robert P.; Klimenkova, Polina; Gaidamakova, Elena K.; Zhou, Carol E.; Stewart, Benjamin J.; Lyman, Mathew G.; Malfatti, Stephanie A.; Rubinfeld, Bonnee; Courtot, Melanie; Singh, Jatinder; Dalgard, Clifton L.; Hamilton, Theron; Frey, Kenneth G.; Gunde-Cimerman, Nina; Dugan, Lawrence; Daly, Michael J.

2018-01-01

Highly concentrated radionuclide waste produced during the Cold War era is stored at US Department of Energy (DOE) production sites. This radioactive waste was often highly acidic and mixed with heavy metals, and has been leaking into the environment since the 1950s. Because of the danger and expense of cleanup of such radioactive sites by physicochemical processes, in situ bioremediation methods are being developed for cleanup of contaminated ground and groundwater. To date, the most developed microbial treatment proposed for high-level radioactive sites employs the radiation-resistant bacterium Deinococcus radiodurans. However, the use of Deinococcus spp. and other bacteria is limited by their sensitivity to low pH. We report the characterization of 27 diverse environmental yeasts for their resistance to ionizing radiation (chronic and acute), heavy metals, pH minima, temperature maxima and optima, and their ability to form biofilms. Remarkably, many yeasts are extremely resistant to ionizing radiation and heavy metals. They also excrete carboxylic acids and are exceptionally tolerant to low pH. A special focus is placed on Rhodotorula taiwanensis MD1149, which was the most resistant to acid and gamma radiation. MD1149 is capable of growing under 66 Gy/h at pH 2.3 and in the presence of high concentrations of mercury and chromium compounds, and forming biofilms under high-level chronic radiation and low pH. We present the whole genome sequence and annotation of R. taiwanensis strain MD1149, with a comparison to other Rhodotorula species. This survey elevates yeasts to the frontier of biology's most radiation-resistant representatives, presenting a strong rationale for a role of fungi in bioremediation of acidic radioactive waste sites. PMID:29375494
Methicillin resistant Staphylococcus aureus contamination of phlebotomy tourniquets and faucets

PubMed

Abeywickrama, T; Amarasinghe, K; Wijerathne, S; Dharmaratne, C; Fernando, D; Senaratna, B C; Gunasekera, H A K M

2018-03-31

Methicillin resistant Staphylococcus aureus (MRSA) is transmitted through direct contact or fomites. The most important means of nosocomial spread is by hospital personnel. However, fomites are being increasingly recognized as sources of nosocomial infection. Our aim was to describe the MRSA contamination rate of phlebotomy tourniquets and faucets in a tertiary care hospital and to compare the contamination of plastic tourniquets with that of fabric tourniquets. A cross-sectional study was carried out in the general wards of a tertiary care hospital in the Colombo District. Two hundred tourniquets were collected and 100 faucets were swabbed and cultured on CHROMagar™ MRSA medium (CHROMagar Microbiology). Contamination rates of 50 plastic tourniquets and 50 fabric tourniquets were compared. MRSA grew in 26% of tourniquets. Majority were plastic tubes. MRSA contamination of tourniquets did not significantly differ by ward (p>0.4). MRSA was found on 26% of faucets. Contamination rate was highest in the common wards for dermatology, dental, rheumatology, and neurology (55.6%), followed by gynaecology (45.2%), cardiology (33.3%), surgery (18.8%), psychiatry (11.1%), and medicine (5.6%). There was a significant difference in rates of contamination of faucets in the different wards (p<0.01). There was no significant difference in the colony count per surface area of the two types of tourniquets after a single use. MRSA contamination rates of tourniquets and faucets were high. Single-use plastic tourniquets were much less contaminated with MRSA than reused tourniquets.

Shallow, non-pumped wells: a low-energy alternative for cleaning polluted groundwater.

PubMed

Hudak, Paul F

2013-07-01

This modeling study evaluated the capability of non-pumped wells with filter media for preventing contaminant plumes from migrating offsite. Linear configurations of non-pumped wells were compared to permeable reactive barriers in simulated shallow homogeneous and heterogeneous aquifers. While permeable reactive barriers enabled faster contaminant removal and shorter distances of contaminant travel, non-pumped wells also prevented offsite contaminant migration. Overall, results of this study suggest that discontinuous, linear configurations of non-pumped wells may be a viable alternative to much more costly permeable reactive barriers for preventing offsite contaminant travel in some shallow aquifers.
Identification of genomic region controlling resistance to aflatoxin contamination in a peanut recombinant inbred line population (Tifrunner XGT-C20)

USDA-ARS?s Scientific Manuscript database

In peanut, limited genetic variation for disease resistance is available in breeding programs necessitating the identification of stable resistance sources for use in cultivar development. ‘Tifrunner’ is a runner cultivar while ‘GT-C20’ is a Spanish-type breeding line with resistance to aflatoxin co...
Prevalence of antibiotic resistance in bacteria isolated from drinking well water available in Guinea-Bissau (West Africa).

PubMed

Machado, A; Bordalo, A A

2014-08-01

The dissemination of antibiotic-resistant bacteria and the spread of antibiotic resistance genes are a major public health concern worldwide, being even proposed as emerging contaminants. The aquatic environment is a recognized reservoir of antibiotic resistant bacteria, and antibiotic resistance genes have been recently detected in drinking water. In this study, the water quality and the prevalence of antibiotic resistance of heterotrophic culturable bacteria were characterized seasonally in wells that serve the population of Guinea-Bissau (West Africa) as the sole source of water for drinking and other domestic proposes. The results revealed that well water was unfit for human consumption independently of the season, owing to high acidity and heavy fecal contamination. Moreover, potentially pathogenic bacteria, which showed resistance to the most prescribed antibiotics in Guinea-Bissau, were isolated from well water, posing an additional health risk. Our results suggest that well water not only fosters the transmission of potential pathogenic bacteria, but also represents an important reservoir for the proliferation of antibiotic resistant bacteria, that can aggravate the potential to cause disease in a very vulnerable population that has no other alternative but to consume such water. Copyright © 2014 Elsevier Inc. All rights reserved.
Field ecology, fungal sex and food contamination involving Aspergillus species

USDA-ARS?s Scientific Manuscript database

Several species within the genus Aspergillus are capable of producing a myriad of toxic secondary metabolites, with aflatoxin being of most concern. These fungi happen to colonize important agricultural commodities, thereby having the potential to contaminate our food with carcinogenic aflatoxins. P...
Chemical approaches to solve mycotoxin problems and improve food safety

USDA-ARS?s Scientific Manuscript database

Foodborne illnesses are experienced by most of the population and are preventable. Agricultural produce can occasionally become contaminated with fungi capable of making mycotoxins that pose health risks and reduce values. Many strategies are employed to keep food safe from mycotoxin contamination. ...
ELECTROCHEMICAL TREATMENT AND RECYCLING OF SPENT PERCHLORATE-CONTAMINATED ION-EXCHANGE REGENERATION BRINE - PHASE I

EPA Science Inventory

Eltron Research & Development, Inc. (Eltron) proposes to develop an ion-selective, polymer membrane electrode capable of detecting perchlorate in water at low parts per billion (ppb) concentrations. With the discovery of perchlorate contamination in an increasing number of...
Healthcare Personnel Attire and Devices as Fomites: A Systematic Review.

PubMed

Haun, Nicholas; Hooper-Lane, Christopher; Safdar, Nasia

2016-11-01

BACKGROUND Transmission of pathogens within the hospital environment remains a hazard for hospitalized patients. Healthcare personnel clothing and devices carried by them may harbor pathogens and contribute to the risk of pathogen transmission. OBJECTIVE To examine bacterial contamination of healthcare personnel attire and commonly used devices. METHODS Systematic review. RESULTS Of 1,175 studies screened, 72 individual studies assessed contamination of a variety of items, including white coats, neckties, stethoscopes, and mobile electronic devices, with varied pathogens including Staphylococcus aureus, including methicillin-resistant S. aureus, gram-negative rods, and enterococci. Contamination rates varied significantly across studies and by device but in general ranged from 0 to 32% for methicillin-resistant S. aureus and gram-negative rods. Enterococcus was a less common contaminant. Few studies explicitly evaluated for the presence of Clostridium difficile. Sampling and microbiologic techniques varied significantly across studies. Four studies evaluated for possible connection between healthcare personnel contaminants and clinical isolates with no unequivocally direct link identified. CONCLUSIONS Further studies to explore the relationship between healthcare personnel attire and devices and clinical infection are needed. Infect Control Hosp Epidemiol 2016;1-7.
Global risk of pharmaceutical contamination from highly populated developing countries.

PubMed

Rehman, Muhammad Saif Ur; Rashid, Naim; Ashfaq, Muhammad; Saif, Ameena; Ahmad, Nasir; Han, Jong-In

2015-11-01

Global pharmaceutical industry has relocated from the west to Asian countries to ensure competitive advantage. This industrial relocation has posed serious threats to the environment. The present study was carried out to assess the possible pharmaceutical contamination in the environment of emerging pharmaceutical manufacturing countries (Bangladesh, China, India and Pakistan). Although these countries have made tremendous progress in the pharmaceutical sector but most of their industrial units discharge wastewater into domestic sewage network without any treatment. The application of untreated wastewater (industrial and domestic) and biosolids (sewage sludge and manure) in agriculture causes the contamination of surface water, soil, groundwater, and the entire food web with pharmaceutical compounds (PCs), their metabolites and transformed products (TPs), and multidrug resistant microbes. This pharmaceutical contamination in Asian countries poses global risks via product export and international traveling. Several prospective research hypotheses including the development of new analytical methods to monitor these PCs/TPs and their metabolites, highly resistant microbial strains, and mixture toxicity as a consequence of pharmaceutical contamination in these emerging pharmaceutical exporters have also been proposed based on the available literature. Copyright © 2013 Elsevier Ltd. All rights reserved.
Enhanced phytoremediation of mixed heavy metal (mercury)-organic pollutants (trichloroethylene) with transgenic alfalfa co-expressing glutathione S-transferase and human P450 2E1.

PubMed

Zhang, Yuanyuan; Liu, Junhong; Zhou, Yuanming; Gong, Tingyun; Wang, Jing; Ge, Yinlin

2013-09-15

Soil contamination is a global environmental problem and many efforts have been made to find efficient remediation methods over the last decade. Moreover, remediation of mixed contaminated soils are more difficult. In the present study, transgenic alfalfa plants pKHCG co-expressing glutathione S-transferase (GST) and human P450 2E1 (CYP2E1) genes were used for phytoremediation of mixed mercury (Hg)-trichloroethylene (TCE) contaminants. Simultaneous expression of GST and CYP2E1 may produce a significant synergistic effect, and leads to improved resistance and accumulation to heavy metal-organic complex contaminants. Based on the tolerance and accumulation assays, pKHCG transgenic plants were more resistant to Hg/TCE complex pollutants and many folds higher in Hg/TCE-accumulation than the non-transgenic control plants in mixed contaminated soil. It is confirmed that GST and CYP2E1 co-expression may be a useful strategy to help achieve mixed heavy metal-organic pollutants phytoremediation. Copyright © 2013 Elsevier B.V. All rights reserved.
The Plume Impingement Contamination II Experiment: Motivation, Design, and Implementation Plan

NASA Technical Reports Server (NTRS)

Lumpkin, Forrest E., III; Albyn, Keith C.; Farrell, Thomas L.

2001-01-01

The International Space Station (ISS) will have a long service life during which it must be able to serve as a capable platform for a wide variety of scientific investigations. In order to provide this capability, the ISS has, at the system level, a design requirement of no more than 100 Angstroms of contaminant deposition per year from "non-quiescent" sources. Non-quiescent sources include the plumes resulting from the firing of reaction control system (ReS) engines on space vehicles visiting the ISS as well as the engines on the ISS itself. Unfortunately, good general plume contamination models do not yet exist. This is due both to the complexity of the problem, making the analytic approach difficult, and to the difficulty in obtaining empirical measurements of contaminant depositions. To address this lack of flight data, NASA Johnson Space Center is planning to fly an experiment, Plume Impingement Contamination-II, to measure the contamination deposition from the Shuttle Orbiter's primary RCS engines as a function angle from plume centerline. This represents the first direct on-orbit measurement of plume impingement contamination away from the nozzle centerline ever performed, and as such is extremely important in validating mathematical models which will be used to quantify the cumulative plume impingement contamination to the ISS over its lifetime. The paper will elaborate further upon the motivation behind making these measurements as well as present the design and implementation plan of this planned experiment.
High pressure reaction cell and transfer mechanism for ultrahigh vacuum spectroscopic chambers

NASA Astrophysics Data System (ADS)

Nelson, A. E.; Schulz, K. H.

2000-06-01

A novel high pressure reaction cell and sample transfer mechanism for ultrahigh vacuum (UHV) spectroscopic chambers is described. The design employs a unique modification of a commercial load-lock transfer system to emulate a tractable microreactor. The reaction cell has an operating pressure range of <1×10-4 to 1000 Torr and can be evacuated to UHV conditions to enable sample transfer into the spectroscopic chamber. Additionally, a newly designed sample holder equipped with electrical and thermocouple contacts is described. The sample holder is capable of resistive specimen heating to 400 and 800 °C with current requirements of 14 A (2 V) and 25 A (3.5 V), respectively. The design enables thorough material science characterization of catalytic reactions and the surface chemistry of catalytic materials without exposing the specimen to atmospheric contaminants. The system is constructed primarily from readily available commercial equipment allowing its rapid implementation into existing laboratories.
Biotransformation of Tributyltin chloride by Pseudomonas stutzeri strain DN2

PubMed Central

Khanolkar, Dnyanada S.; Naik, Milind Mohan; Dubey, Santosh Kumar

2014-01-01

A bacterial isolate capable of utilizing tributyltin chloride (TBTCl) as sole carbon source was isolated from estuarine sediments of west coast of India and identified as Pseudomonas stutzeri based on biochemical tests and Fatty acid methyl ester (FAME) analysis. This isolate was designated as strain DN2. Although this bacterial isolate could resist up to 3 mM TBTCl level, it showed maximum growth at 2 mM TBTCl in mineral salt medium (MSM). Pseudomonas stutzeri DN2 exposed to 2 mM TBTCl revealed significant alteration in cell morphology as elongation and shrinkage in cell size along with roughness of cell surface. FTIR and NMR analysis of TBTCl degradation product extracted using chloroform and purified using column chromatography clearly revealed biotransformation of TBTCl into Dibutyltin dichloride (DBTCl2) through debutylation process. Therefore, Pseudomonas stutzeri strain DN2 may be used as a potential bacterial strain for bioremediation of TBTCl contaminated aquatic environmental sites. PMID:25763027
Trace Contaminant Control During the International Space Station's On-Orbit Assembly and Outfitting

NASA Technical Reports Server (NTRS)

Perry, J. L.

2017-01-01

Achieving acceptable cabin air quality must balance competing elements during spacecraft design, assembly, ground processing, and flight operations. Among the elements that contribute to the trace chemical contaminant load and, therefore, the cabin air quality aboard crewed spacecraft are the vehicle configuration, crew size and activities, mission duration and objectives, materials selection, and vehicle manufacturing and preflight ground processing methods. Trace chemical contaminants produced from pervasive sources such as equipment offgassing, human metabolism, and cleaning fluids during preflight ground processing present challenges to maintaining acceptable cabin air quality. To address these challenges, both passive and active contamination control techniques are used during a spacecraft's design, manufacturing, preflight preparation, and operational phases. Passive contamination control methods seek to minimize the equipment offgassing load by selecting materials, manufacturing processes, preflight preparation processes, and in-flight operations that have low chemical offgassing characteristics. Passive methods can be employed across the spacecraft's entire life cycle from conceptual design through flight operations. However, because the passive contamination control techniques cannot fully eliminate the contaminant load, active contamination control equipment must be deployed aboard the spacecraft to purify and revitalize the cabin atmosphere during in-flight operations. Verifying that the passive contamination control techniques have successfully maintained the total trace contaminant load within the active contamination control equipment's capabilities occurs late in the preflight preparation stages. This verification consists of subjecting the spacecraft to an offgassing test to determine the trace contaminant load. This load is then assessed versus the active contamination control equipment's capabilities via trace contaminant control (TCC) engineering analysis. During the International Space Station's (ISS's) on-orbit assembly and outfitting, a series of engineering analyses were conducted to evaluate how effective the passive TCC methods were relative to providing adequate operational margin for the active TCC equipment's capabilities aboard the ISS. These analyses were based on habitable module and cargo vehicle offgassing test results. The offgassing test for a fully assembled module or cargo vehicle is an important preflight spacecraft evaluation method that has been used successfully during all crewed spacecraft programs to provide insight into how effectively the passive contamination control methods limit the equipment offgassing component of the overall trace contaminant generation load. The progression of TCC assessments beginning in 1998 with the ISS's first habitable element launch and continuing through the final pressurized element's arrival in 2010 are presented. Early cargo vehicle flight assessments between 2008 and 2011 are also presented as well as a discussion on predictive methods for assessing cargo via a purely analytical technique. The technical approach for TCC employed during this 13-year period successfully maintained the cabin atmospheric quality within specified parameters during the technically challenging ISS assembly and outfitting stages. The following narrative provides details on the important role of spacecraft offgassing testing, trace contaminant performance requirements, and flight rules for achieving the ultimate result-a cabin environment that enables people to live and work safely in space.
Distribution and mobility of copper, zinc and lead in plant-sediment systems of Quanzhou Bay estuary, China.

PubMed

Li, Yu-Hong; Hu, Hong-You; Liu, Jing-Chun; Wu, Gui-Lan

2010-03-01

The distribution, mobility and potential risks of Cu, Zn, and Pb in four typical plant-sediment co-systems of the Quanzhou Bay estuary wetland in southeast China were investigated using a sequential extraction procedure. The results show that the sediments were moderately or heavily contaminated with Zn and Pb in all four plant communities, and the plant-sediment systems could act as a sink for the heavy metals. In all investigated sediments, only a small proportion of measured heavy metals were distributed in exchangeable fraction and carbonate fraction, while the reducible fraction contained the highest amount of Zn and Pb of the total readily bioavailable fractions, and the oxidizable fraction exhibited a higher retention capacity for Zn and Cu, but lower for Pb. Alternanthera philoxeroides had the best ability to accumulate heavy metals among the four species. Phragmites communis was quite tolerant to Zn and Pb and had a good capability to transfer Zn and Pb. Aegiceras corniculatum seems to be effective in resisting heavy metal pollution, and therefore cannot serve as an indicator of contamination. The urgent need for many local enterprises is to carry out high-tech cleaner production to reduce the emission of pollutants and achieve a resource-economical and environment-friendly development.
Molecular Detection of Breast Cancer

DTIC Science & Technology

1998-02-01

treatment-resistant cancer cells. Clearly new approaches are needed to treat these diseases. This project is designed to develop novel approaches to...detect breast cancer cells that contaminate peripheral blood and bone marrow, and to remove such contaminating cells. An RT-PCR assay has been developed ...to detect breast cancer cells, and a novel gene therapy vector has been developed to kill contaminating cancer cells. Blood and bone marrow samples
Corrosion Sensor for Monitoring the Service Condition of Chloride-Contaminated Cement Mortar

PubMed Central

Lu, Shuang; Ba, Heng-Jing

2010-01-01

A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (Rp) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (Rs). The results show that the polarization resistance is related to the chloride content and Rs; ln (Rp) is linearly related to the Rs values in mortar without added chloride. The relationships observed between the Rp of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that Rs can indicate the corrosion state of concrete structures. PMID:22319347
Risk of antibiotic resistance from metal contaminated soils

NASA Astrophysics Data System (ADS)

Knapp, Charles

2013-04-01

It is known that contaminated soils can lead to increased incidence of illness and disease, but it may also prevent our ability to fight disease. Many antibiotic resistant genes (ARG) acquired by bacteria originate from the environment. It is important to understand factors that influence levels of ARG in the environment, which could affect us clinically and agriculturally. The presence of elevated metal content in soils often promotes antibiotic resistance in exposed microorganisms. Using qPCR, the abundances of ARG to compare levels with geochemical conditions in randomly selected soils from several countries. Many ARG positively correlated with soil metal content, especially copper, chromium, nickel, lead, and iron. Results suggest that geochemical metal conditions influence the potential for antibiotic resistance in soil, which might be used to estimate baseline gene presence on various landscape scales and may translate to epidemiological risk of antibiotic-resistance transmission from the environment. This suggests that we may have to reconsider tolerances of metal pollution in the environment.
Antibiotic resistance of Escherichia coli isolated from a poultry slaughterhouse.

PubMed

Gregova, Gabriela; Kmetova, Marta; Kmet, Vladimfr; Venglovsky, Jan; Feher, Alexander

2012-01-01

The aim of the study was to investigate the antibiotic resistant E. coli strains isolated from bioaerosols and surface swabs in a slaughterhouse as a possible source of poultry meat contamination. The highest air coliforms contamination was during shackling, killing and evisceration of poultry. The strains showed resistance to ampicillin (89%), ceftiofur (62%) and cefquinome (22%), while resistance to ampicillin with sulbactam was only 6%. Resistance to streptomycin and gentamicin was detected in 43% vs. 14% isolates; to tetracycline 33%; to chloramphenicol and florfenicol in 10% vs. 18% isolates; to cotrimoxazol in 35% isolates; to enrofloxacin in 43% isolates. The higher MIC of ceftazidime (3.6 mg x l(-1)) and ceftriaxon (5.2 mg x l(-1)) revealed the presence of ESBLs in 43% of isolates. From 19 selected phenotypically ESBL positive strains, 16 consisted of CMY-2 genes, while CTX-M genes were not detected by PCR. Maldi tof analysis of selected E. coli showed a clear clonal relatedness of environmental strains from various withdrawals.
EMERGING TECHNOLOGY SUMMARY: VITRIFICATION OF SOILS CONTAMINATED BY HAZARDOUS AND/OR RADIOACTIVE WASTES

EPA Science Inventory

A performance summary of an advanced multifuel-capable combustion and melting system (CMS) for the vitrification of hazardous wastes is presented. Vortex Corporation has evaluated its patented CMS for use in the remediation of soils contaminated with heavy metals and radionuclid...
Inheritance of mercury tolerance in the aquatic oligochaete Tubifex tubifex.

PubMed

Vidal, Dora Elva; Horne, Alex John

2003-09-01

Resistance to contaminants is an important yet unmeasured factor in sediment toxicity tests. The rate at which mercury resistance develops and its genetic persistence in the oligochaete worm Tubifex tubifex were studied under laboratory conditions. Worms were raised for four generations under two different sediment treatments, one reference clean sediment, the other contaminated with mercury. Worms raised in mercury-contaminated sediment developed mercury tolerance that persisted even when the worms were raised for three subsequent generations in clean sediment. Mercury tolerance was determined by comparative water-only toxicity tests with mercury as the only stressor. Control worms had a mean lethal concentration (LC50) of 0.18 mg/L(-1). Worms exposed to high levels of mercury in sediment had high mercury tolerance with a mean LC50 of 1.40 mg/L(-1). When mercury-tolerant and control mercury-intolerant worms were crossed, their descendants also demonstrated mercury tolerance during lethal toxicity tests. The LC50 for worm descendants resulting from this cross was 1.39 mg/L(-1). Adaptation to mercury exposures occurred rapidly in this group of worms and appears to be due to both phenotypic and genotypic mechanisms. Development of contaminant resistance and adaptation may be common phenomena in aquatic benthic invertebrates, which should be considered during the design and interpretation of toxicity tests.

Contamination pathways of spore-forming bacteria in a vegetable cannery.

PubMed

Durand, Loïc; Planchon, Stella; Guinebretiere, Marie-Hélène; André, Stéphane; Carlin, Frédéric; Remize, Fabienne

2015-06-02

Spoilage of low-acid canned food during prolonged storage at high temperatures is caused by heat resistant thermophilic spores of strict or facultative bacteria. Here, we performed a bacterial survey over two consecutive years on the processing line of a French company manufacturing canned mixed green peas and carrots. In total, 341 samples were collected, including raw vegetables, green peas and carrots at different steps of processing, cover brine, and process environment samples. Thermophilic and highly-heat-resistant thermophilic spores growing anaerobically were counted. During vegetable preparation, anaerobic spore counts were significantly decreased, and tended to remain unchanged further downstream in the process. Large variation of spore levels in products immediately before the sterilization process could be explained by occasionally high spore levels on surfaces and in debris of vegetable combined with long residence times in conditions suitable for growth and sporulation. Vegetable processing was also associated with an increase in the prevalence of highly-heat-resistant species, probably due to cross-contamination of peas via blanching water. Geobacillus stearothermophilus M13-PCR genotypic profiling on 112 isolates determined 23 profile-types and confirmed process-driven cross-contamination. Taken together, these findings clarify the scheme of contamination pathway by thermophilic spore-forming bacteria in a vegetable cannery. Copyright © 2015 Elsevier B.V. All rights reserved.
PSYCHROPHILIC PSEUDOMONAS SP. RESISTANT TO MERCURY FROM PAVLODAR, KAZAKHSTAN

EPA Science Inventory

As mercury circulates and deposits globally, the remediation of extensive mercury contamination surrounding a chloralkali plant in Pavlodar, Kazakhstan is critical. High-levels of mercury contamination exist within the confines of the plant, at nearby off-site waste storage and e...
Two-dimensional direct-current resistivity survey to supplement borehole data in ground-water models of the former Blaine Naval Ammunition Depot, Hastings, Nebraska, September 2003

USGS Publications Warehouse

Kress, Wade H.; Ball, Lyndsay B.; Teeple, Andrew; Turco, Michael J.

2006-01-01

The former Blaine Naval Ammunition Depot located immediately southeast of Hastings, Nebraska, was an ammunition facility during World War II and the Korean Conflict. Waste-management practices during operation and decommissioning of the former Depot resulted in soil and ground-water contamination. Ground-water models have been used by the U.S. Army Corps of Engineers to provide information on the fate and transport of contaminants on the former Depot site. During September 2003, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, Kansas City District, conducted a pilot study to collect two-dimensional direct-current resistivity data on the site along six profiles near existing monitoring wells. The inversion results of field data from five of the six two-dimensional direct-current resistivity profiles display distinct electrical stratigraphy consistent with three resistivity units (low resistivity, high resistivity, and low resistivity). These three resistivity units correlate with rock-stratigraphic or hydrogeologic units described prior to this study. To interpret the resistivity profiles, additional data extending through the lower confining unit into the underlying Niobrara Formation could be used with the existing data to construct forward models for data analysis and interpretation.
Rapid environmental contamination of a new nursing home with antimicrobial-resistant organisms preceding occupation by residents.

PubMed

Ludden, C; Cormican, M; Austin, B; Morris, D

2013-04-01

Nursing homes are reservoirs for antimicrobial-resistant organisms (AROs). This study examined the time to environmental contamination with AROs in a new-build nursing home. Environmental sites in an occupied nursing home (N = 18) and a newly built replacement nursing home (N = 21) were monitored during an 11-week period before and after residents transferred between buildings. Meticillin-resistant Staphylococcus aureus was detected during commissioning in the new building and was a frequent finding throughout the building after residents had moved in. Extended-spectrum beta-lactamase-producing E. coli O25b:ST131 was detected once. Copyright © 2012 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
Heavy metal resistance of Thiobacillus spp. isolated from tin mining area in Bestari Jaya, Selangor

NASA Astrophysics Data System (ADS)

Prabhakaran, Pranesha; Ashraf, Muhammad Aqeel; Aqma, Wan Syaidatul

2016-11-01

Increased anthropogenic activities such as mining have contributed to accumulation of heavy metals in the environment. Microorganisms that are found in the contaminated area develop resistance toward the heavy metals after a prolonged exposure. Screenings for bacterial resistance to metal tin were conducted using isolated Thiobacillus spp. from a tin mining area at Bestari Jaya, Selangor. Two isolated Thiobacillus spp. able to show growth without inhibition up to 300 ppm. IC50 that indicate 50% inhibition of the bacterial growth for both isolates, TB1 and TB2 are 496.03 ppm and 514.27 ppm respectively under tin-stressed condition. Adaptation of these microorganisms toward heavy metal could be exploited for bioremediation of heavy metals at contaminated sites.
Enterobacter asburiae KUNi5, a Nickel Resistant Bacterium for Possible Bioremediation of Nickel Contaminated Sites.

PubMed

Paul, Anirudha; Mukherjee, Samir Kumar

2016-01-01

Nickel resistant bacterial strain Enterobacter asburiae KUNi5 was isolated and showed resistance up to 15 mM and could remove Ni optimally better at 37 degrees C and pH 7. Maximum removal was found at initial concentration of 0.5 to 2 mM, however, growth and Ni removal were affected by other heavy metals. Major amount of the metal was accumulated in the membrane fractions and certain negatively charged groups were found responsible for Ni binding. KUNi5 could also produce 1-aminocyclopropane-1-carboxylate deaminase, indole-acetic acid and siderophore. It seems that KUNi5 could be a possible candidate for Ni detoxification and plant growth promotion in Ni-contaminated field.
Comparative Metagenomics of Freshwater Microbial Communities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hemme, Chris; Deng, Ye; Tu, Qichao

2010-05-17

Previous analyses of a microbial metagenome from uranium and nitric-acid contaminated groundwater (FW106) showed significant environmental effects resulting from the rapid introduction of multiple contaminants. Effects include a massive loss of species and strain biodiversity, accumulation of toxin resistant genes in the metagenome and lateral transfer of toxin resistance genes between community members. To better understand these results in an ecological context, a second metagenome from a pristine groundwater system located along the same geological strike was sequenced and analyzed (FW301). It is hypothesized that FW301 approximates the ancestral FW106 community based on phylogenetic profiles and common geological parameters; however,more » even if is not the case, the datasets still permit comparisons between healthy and stressed groundwater ecosystems. Complex carbohydrate metabolism has been almost entirely lost in the stressed ecosystem. In contrast, the pristine system encodes a wide diversity of complex carbohydrate metabolism systems, suggesting that carbon turnover is very rapid and less leaky in the healthy groundwater system. FW301 encodes many (~;;160+) carbon monoxide dehydrogenase genes while FW106 encodes none. This result suggests that the community is frequently exposed to oxygen from aerated rainwater percolating into the subsurface, with a resulting high rate of carbon metabolism and CO production. When oxygen levels fall, the CO then serves as a major carbon source for the community. FW301 appears to be capable of CO2 fixation via the reductive carboxylase (reverse TCA) cycle and possibly acetogenesis, activities; these activities are lacking in the heterotrophic FW106 system which relies exclusively on respiration of nitrate and/or oxygen for energy production. FW301 encodes a complete set of B12 biosynthesis pathway at high abundance suggesting the use of sodium gradients for energy production in the healthy groundwater community. Overall comparative analysis suggests that the introduction of contaminants is accompanied by a decrease in biodiversity, loss of nutrient cycling, less metabolic diversity, increased respiration and dominance by r-strategists. These results are consistent with trends predicted for stressed ecosystems.« less
Incorporating Water Boiling in the Numerical Modelling of Thermal Remediation by Electrical Resistance Heating

NASA Astrophysics Data System (ADS)

Molnar, I. L.; Krol, M.; Mumford, K. G.

2017-12-01

Developing numerical models for subsurface thermal remediation techniques - such as Electrical Resistive Heating (ERH) - that include multiphase processes such as in-situ water boiling, gas production and recovery has remained a significant challenge. These subsurface gas generation and recovery processes are driven by physical phenomena such as discrete and unstable gas (bubble) flow as well as water-gas phase mass transfer rates during bubble flow. Traditional approaches to multiphase flow modeling soil remain unable to accurately describe these phenomena. However, it has been demonstrated that Macroscopic Invasion Percolation (MIP) can successfully simulate discrete and unstable gas transport1. This has lead to the development of a coupled Electro Thermal-MIP Model2 (ET-MIP) capable of simulating multiple key processes in the thermal remediation and gas recovery process including: electrical heating of soil and groundwater, water flow, geological heterogeneity, heating-induced buoyant flow, water boiling, gas bubble generation and mobilization, contaminant mass transport and removal, and additional mechanisms such as bubble collapse in cooler regions. This study presents the first rigorous validation of a coupled ET-MIP model against two-dimensional water boiling and water/NAPL co-boiling experiments3. Once validated, the model was used to explore the impact of water and co-boiling events and subsequent gas generation and mobilization on ERH's ability to 1) generate, expand and mobilize gas at boiling and NAPL co-boiling temperatures, 2) efficiently strip contaminants from soil during both boiling and co-boiling. In addition, a quantification of the energy losses arising from steam generation during subsurface water boiling was examined with respect to its impact on the efficacy of thermal remediation. While this study specifically targets ERH, the study's focus on examining the fundamental mechanisms driving thermal remediation (e.g., water boiling) renders these results applicable to a wide range of thermal and gas-based remediation techniques. 1. Mumford, K. G., et al. (2010), Adv. Water Resour. 2010, 33 (4), 504-513. 2. Krol, M. M., et al. (2011), Adv. Water Resour. 2011, 34 (4), 537-549. 3. Hegele, P. R. and Mumford, K. G. Journal of Contaminant Hydrology 2014, 165, 24-36.
Genesis Solar Wind Collector Cleaning Assessment: Update on 60336 Sample Case Study

NASA Technical Reports Server (NTRS)

Goreva, Y. S.; Allums, K. K.; Gonzalez, C. P.; Jurewicz, A. J.; Burnett, D. S.; Allton, J. H.; Kuhlman, K. R.; Woolum, D.

2015-01-01

To maximize the scientific return of Genesis Solar Wind return mission it is necessary to characterize and remove a crash-derived particle and thin film surface contamination. A small subset of Genesis mission collector fragments are being subjected to extensive study via various techniques. Here we present an update on the sample 60336, a Czochralski silicon (Si-CZ) based wafer from the bulk array (B/C). This sample has undergone multiple cleaning steps (see the table below): UPW spin wash, aggressive chemical cleanings (including aqua regia, hot xylene and RCA1), as well as optical and chemical (EDS, ToF-SIMS) imaging. Contamination appeared on the surface of 60336 after the initial 2007 UPW cleaning. Aqua regia and hot xylene treatment (8/13/2013) did little to remove contaminants. The sample was UPW cleaned for the third time and imaged (9/16/13). The UPW removed the dark stains that were visible on the sample. However, some features, like "the Flounder" (a large, 100 micron feature in Fig. 1b) appeared largely intact, resisting all previous cleaning efforts. These features were likely from mobilized adhesive, derived from the Post-It notes used to stabilize samples for transport from Utah after the hard landing. To remove this contamination, an RCA step 1 organic cleaning (RCA1) was employed. Although we are still uncertain on the nature of the Flounder and why it is resistant to UPW and aqua regia/hot xylene treatment, we have found RCA1 to be suitable for its removal. It is likely that the glue from sticky pads used during collector recovery may have been a source for resistant organic contamination [9]; however [8] shows that UPW reaction with crash-derived organic contamination does not make particle removal more difficult.
Improved fire resistant radio frequency anechoic materials

NASA Technical Reports Server (NTRS)

Robinson, D. A.

1969-01-01

Protective, flameproof foam covering improves the resistance to fire and surface contamination of low-cost radio frequency absorbing and shielding anechoic materials. This promotes safety of operating personnel and equipment being tested in an otherwise combustible anechoic chamber.
Surfactant effects on desorption rate of nonionic organic compounds from soils to water

USGS Publications Warehouse

Cesare, David Di; Smith, James A.

1994-01-01

The widespread occurrence of organic contamination in groundwater systems has become an important environmental concern. Of particular interest are nonionic organic compounds, which sorb strongly to natural soil as a result of their characteristic low aqueous solubilities and hydrophobic nature. Consequently, the remediation of nonionic organic contamination in groundwater systems is often highly dependent on contaminant desorption from the sorbed to aqueous phase. The kinetics of desorption will significantly influence the extraction efficiency of pump-and-treat remedial methods that are capable of removing only dissolved phase contaminants.
Susceptibility to aflatoxin contamination among maize landraces from Mexico.

PubMed

Ortega-Beltran, Alejandro; Guerrero-Herrera, Manuel D J; Ortega-Corona, Alejandro; Vidal-Martinez, Victor A; Cotty, Peter J

2014-09-01

Maize, the critical staple food for billions of people, was domesticated in Mexico about 9,000 YBP. Today, a great array of maize landraces (MLRs) across rural Mexico is harbored in a living library that has been passed among generations since before the establishment of the modern state. MLRs have been selected over hundreds of generations by ethnic groups for adaptation to diverse environmental settings. The genetic diversity of MLRs in Mexico is an outstanding resource for development of maize cultivars with beneficial traits. Maize is frequently contaminated with aflatoxins by Aspergillus flavus, and resistance to accumulation of these potent carcinogens has been sought for over three decades. However, MLRs from Mexico have not been evaluated as potential sources of resistance. Variation in susceptibility to both A. flavus reproduction and aflatoxin contamination was evaluated on viable maize kernels in laboratory experiments that included 74 MLR accessions collected from 2006 to 2008 in the central west and northwest regions of Mexico. Resistant and susceptible MLR accessions were detected in both regions. The most resistant accessions accumulated over 99 % less aflatoxin B1 than did the commercial hybrid control Pioneer P33B50. Accessions supporting lower aflatoxin accumulation also supported reduced A. flavus sporulation. Sporulation on the MLRs was positively correlated with aflatoxin accumulation (R = 0.5336, P < 0.0001), suggesting that resistance to fungal reproduction is associated with MLR aflatoxin resistance. Results of the current study indicate that MLRs from Mexico are potentially important sources of aflatoxin resistance that may contribute to the breeding of commercially acceptable and safe maize hybrids and/or open pollinated cultivars for human and animal consumption.
Characterization of the Rhodococcus sp. MK1 strain and its pilot application for bioremediation of diesel oil-contaminated soil.

PubMed

Kis, Ágnes Erdeiné; Laczi, Krisztián; Zsíros, Szilvia; Kós, Péter; Tengölics, Roland; Bounedjoum, Naila; Kovács, Tamás; Rákhely, Gábor; Perei, Katalin

2017-12-01

Petroleum hydrocarbons and derivatives are widespread contaminants in both aquifers and soil, their elimination is in the primary focus of environmental studies. Microorganisms are key components in biological removal of pollutants. Strains capable to utilize hydrocarbons usually appear at the contaminated sites, but their metabolic activities are often restricted by the lack of nutrients and/or they can only utilize one or two components of a mixture. We isolated a novel Rhodococcus sp. MK1 strain capable to degrade the components of diesel oil simultaneously. The draft genome of the strain was determined and besides the chromosome, the presence of one plasmid could be revealed. Numerous routes for oxidation of aliphatic and aromatic compounds were identified. The strain was tested in ex situ applications aiming to compare alternative solutions for microbial degradation of hydrocarbons. The results of bioaugmentation and biostimulation experiments clearly demonstrated that - in certain cases - the indigenous microbial community could be exploited for bioremediation of oil-contaminated soils. Biostimulation seems to be efficient for removal of aged contaminations at lower concentration range, whereas bioaugmentation is necessary for the treatment of freshly and highly polluted sites.
Comparative metagenomics reveals impact of contaminants on groundwater microbiomes

DOE PAGES

Hemme, Christopher L.; Tu, Qichao; Shi, Zhou; ...

2015-10-31

To understand patterns of geochemical cycling in pristine versus contaminated groundwater ecosystems, pristine shallow groundwater (FW301) and contaminated groundwater (FW106) samples from the Oak Ridge Integrated Field Research Center (OR-IFRC) were sequenced and compared to each other to determine phylogenetic and metabolic difference between the communities. Proteobacteria (e.g., Burkholderia, Pseudomonas) are the most abundant lineages in the pristine community, though a significant proportion ( >55%) of the community is composed of poorly characterized low abundance (individually <1%) lineages. The phylogenetic diversity of the pristine community contributed to a broader diversity of metabolic networks than the contaminated community. In addition, themore » pristine community encodes redundant and mostly complete geochemical cycles distributed over multiple lineages and appears capable of a wide range of metabolic activities. In contrast, many geochemical cycles in the contaminated community appear truncated or minimized due to decreased biodiversity and dominance by Rhodanobacter populations capable of surviving the combination of stresses at the site. In conclusion, these results indicate that the pristine site contains more robust and encodes more functional redundancy than the stressed community, which contributes to more efficient nutrient cycling and adaptability than the stressed community.« less
Protists from a sewage‐contaminated aquifer on cape cod, Massachusetts

USGS Publications Warehouse

Novarino, Gianfranco; Warren, Alan; Kinner, Nancy E.; Harvey, Ronald W.

1994-01-01

Several species of flagellates (genera Bodo, Cercomonas, Cryptaulax, Cyathomonas, Goniomonas, Spumella) have been identified in cultures from a plume of organic contamination (treated sewage effluent) within an aquifer on Cape Cod, Massachusetts. Amoebae and numerous unidentifiable 2‐ to 3‐μm flagellates have also been observed. As a rule, flagellates were associated with solid surfaces, or were capable of temporary surface attachment, corroborating earlier observations from in situ and column transport experiments suggesting that protists in the Massachusetts aquifer have a high propensity for association with sediment grain surfaces. Based on the fact that cultures from the uncontaminated part of the aquifer yielded only a few species of protists, it is hypothesized that the greater abundance and variety of food sources in the contaminant plume is capable of supporting a greater number of protistan species.
Detection of Salmonella spp. in Retail Raw Food Samples from Vietnam and Characterization of Their Antibiotic Resistance▿

PubMed Central

Van, Thi Thu Hao; Moutafis, George; Istivan, Taghrid; Tran, Linh Thuoc; Coloe, Peter J.

2007-01-01

A study was conducted to examine the levels of Salmonella spp. contamination in raw food samples, including chicken, beef, pork, and shellfish, from Vietnam and to determine their antibiotic resistance characteristics. A total of 180 samples were collected and examined for the presence of Salmonella spp., yielding 91 Salmonella isolates. Sixty-one percent of meat and 18% of shellfish samples were contaminated with Salmonella spp. Susceptibility of all isolates to a variety of antimicrobial agents was tested, and resistance to tetracycline, ampicillin/amoxicillin, nalidixic acid, sulfafurazole, and streptomycin was found in 40.7%, 22.0%, 18.7%, 16.5%, and 14.3% of the isolates, respectively. Resistance to enrofloxacin, trimethoprim, chloramphenicol, kanamycin, and gentamicin was also detected (8.8 to 2.2%). About half (50.5%) of the isolates were resistant to at least one antibiotic, and multiresistant Salmonella isolates, resistant to at least three different classes of antibiotics, were isolated from all food types. One isolate from chicken (serovar Albany) contained a variant of the Salmonella genomic island 1 antibiotic resistance gene cluster. The results show that antibiotic resistance in Salmonella spp. in raw food samples from Vietnam is significant. PMID:17766455
ENVIRONMENTAL RESEARCH BRIEF: SPATIAL HETEROGENEITY OF GEOCHEMICAL AND HYDROLOGIC PARAMETERS AFFECTING METAL TRANSPORT IN GROUND WATER

EPA Science Inventory

Reliable assessment of the hazards or risks arising from groundwater contamination and the design of effective means of rehabilitation of contaminated sites requires the capability to predict the movement and fate of dissolved solutes in groundwater. The modeling of metal transp...
ENVIRONMENTAL RESEARCH BRIEF: SPATIAL HETEROGENEITY OF GEOCHEMICAL AND HYDROLOGIC PARAMETERS AFFECTING METAL TRANSPORT IN GROUNDWATER

EPA Science Inventory

Reliable assessment of the hazards or risks arising from groundwater contamination and the design of effective means of rehabilitation of contaminated sites requires the capability to predict the movement and fate of dissolved solutes in groundwater. he modeling of metal transpor...
The resistance of Bacillus atrophaeus spores to the bactericidal activity of peracetic acid is influenced by both the nature of the solid substrates and the mode of contamination.

PubMed

Grand, I; Bellon-Fontaine, M-N; Herry, J-M; Hilaire, D; Moriconi, F-X; Naïtali, M

2010-11-01

To evaluate the impact of the mode of contamination in relation with the nature of solid substrates on the resistance of spores of Bacillus atrophaeus -selected as surrogates of Bacillus anthracis- to a disinfectant, peracetic acid. Six materials confronted in urban and military environments were selected for their different structural and physicochemical properties. In parallel, two modes of contamination were examined, i.e. deposition and immersion. Deposition was used to simulate contamination by an aerosol and immersion by an extended contact with liquids. A pronounced difference in the biocontamination levels and spatial organization of spores was observed depending on the mode of contamination and the nature of the solid substrate considered, with consequences on decontamination. Contamination by immersion led to lower efficiency of peracetic acid decontamination than contamination by deposition. Infiltration of spores into porous materials after immersion is one reason. In contrast, the deposition mode aggregates cells at the surface of materials, explaining the similar disinfecting behaviour of porous and nonporous substrates when considering this inoculation route. The inoculation route was shown to be as influential a parameter as material characteristics (porosity and wettability) for decontamination efficacy. These results provide comparative information for the decontamination of B. atrophaeus spores in function of the mode of contamination and the nature of solid substrates. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology. No claim to French government works.
Contamination of environmental surfaces by methicillin-resistant Staphylococcus aureus (MRSA) in rooms of inpatients with MRSA-positive body sites.

PubMed

Kurashige, E Jessica Ohashi; Oie, Shigeharu; Furukawa, H

2016-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) can contaminate environmental surfaces that are frequently touched by the hands of patients with MRSA colonization/infection. There have been many studies in which the presence or absence of MRSA contamination was determined but no studies in which MRSA contamination levels were also evaluated in detail. We evaluated MRSA contamination of environmental surfaces (overbed tables, bed side rails, and curtains) in the rooms of inpatients from whom MRSA was isolated via clinical specimens. We examined the curtains within 7-14 days after they had been newly hung. The environmental surfaces were wiped using gauze (molded gauze for wiping of surface bacteria; 100% cotton, 4cm×8cm) moistened with sterile physiological saline. The MRSA contamination rate and mean counts (range) were 25.0% (6/24 samples) and 30.6 (0-255)colony-forming units (cfu)/100cm(2), respectively, for the overbed tables and 31.6% (6/19 samples) and 159.5 (0-1620)cfu/100cm(2), respectively, for the bed side rails. No MRSA was detected in 24 curtain samples. The rate of MRSA contamination of environmental surfaces was high for the overbed tables and bed side rails but low for the curtains. Therefore, at least until the 14th day of use, frequent disinfection of curtains may be not necessary. Copyright © 2016. Published by Elsevier Editora Ltda.

THE BEHAVIOR OF MICROORGANISMS RESISTANT TO MERCURY FROM PAVLODAR, KAZAKHSTAN

EPA Science Inventory

There is extensive mercury contamination surrounding a chloralkali plant in Pavlodar, Kazakhstan that operated from 1970 to 1990. High-level mercury contamination exists within the confines of the plant, at nearby off-site waste storage and evaporation ponds, in Balkyldak Lake w...
Germination of Spores of Astrobiologically Relevant Bacillus Species in High-Salinity Environments

NASA Astrophysics Data System (ADS)

Nagler, Katja; Julius, Christina; Moeller, Ralf

2016-07-01

In times of increasing space exploration and search for extraterrestrial life, new questions and challenges for planetary protection, aiming to avoid forward contamination of different planets or moons with terrestrial life, are emerging. Spore-forming bacteria such as Bacillus species have a high contamination potential due to their spores' extreme resistance, enabling them to withstand space conditions. Spores require liquid water for their conversion into a growing cell (i.e., spore germination and subsequent growth). If present, water on extraterrestrial planets or moons is likely to be closely associated with salts (e.g., in salty oceans or brines), thus constituting high-salinity environments. Spores of Bacillus subtilis can germinate despite very high salt concentrations, although salt stress does exert negative effects on this process. In this study, germination and metabolic reactivation ("outgrowth") of spores of five astrobiologically relevant Bacillus species (B. megaterium, B. pumilus SAFR-032, B. nealsonii, B. mojavensis, and B. vallismortis) in high salinity (≤3.6 M NaCl) were investigated. Spores of different species exhibited different germination and outgrowth capabilities in high salinity, which strongly depended on germination conditions, especially the exact composition of the medium. In this context, a new "universal" germination trigger for Bacillus spores, named KAGE (KCl, L-alanine, D-glucose, ectoine), was identified, which will be very useful for future comparative germination and outgrowth studies on different Bacillus species. Overall, this study yielded interesting new insights on salt stress effects on spore germination and points out the difficulty of predicting the potential of spores to contaminate salty environments on extraterrestrial celestial bodies.
Using Optically Stimulated Electron Emission as an Inspection Method to Monitor Surface Contamination

NASA Technical Reports Server (NTRS)

Lingbloom, Mike S.

2008-01-01

During redesign of the Space Shuttle reusable solid rocket motor (RSRM), NASA amended the contract with ATK Launch Systems (then Morton Thiokol Inc.) with Change Order 966 to implement a contamination control and cleanliness verification method. The change order required: (1) A quantitative inspection method (2) A written record of actual contamination levels versus a known reject level (3) A method that is more sensitive than existing methods of visual and black light inspection. Black light inspection is only useful for inspection of contaminants that fluoresce near the 365 nm spectral line and is not useful for inspection of most silicones that will not produce strong fluorescence. Black light inspection conducted by a qualified inspector under controlled light is capable of detecting Conoco HD-2 grease in gross amounts and is very subjective due to operator sensitivity. Optically stimulated electron emission (OSEE), developed at the Materials and Process Laboratory at Marshall Space Flight Center (MSFC), was selected to satisfy Change Order 966. OSEE offers several important advantages over existing laboratory methods with similar sensitivity, e.g., spectroscopy and nonvolatile residue sampling, which provide turn around time, real time capability, and full coverage inspection capability. Laboratory methods require sample gathering and in-lab analysis, which sometimes takes several days to get results. This is not practical in a production environment. In addition, these methods do not offer full coverage inspection of the large components
Mapping microbial ecosystems and spoilage-gene flow in breweries highlights patterns of contamination and resistance

PubMed Central

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

2015-01-01

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

PubMed

Londero, Alejandra; León Peláez, María A; Diosma, Gabriela; De Antoni, Graciela L; Abraham, Analía G; Garrote, Graciela L

2014-12-01

Fungal contamination of poultry feed causes economic losses to industry and represents a potential risk to animal health. The aim of the present study was to analyze the effectiveness of whey fermented with kefir grains as additive to reduce fungal incidence, thus improving feed safety. Whey fermented for 24 h at 20 °C with kefir grains (100 g L(-1) ) reduced conidial germination of Aspergillus flavus, Aspergillus parasiticus, Aspergillus terreus, Aspergillus fumigatus, Penicillium crustosum, Trichoderma longibrachiatum and Rhizopus sp. Poultry feed supplemented with fermented whey (1 L kg(-1) ) was two to four times more resistant to fungal contamination than control feed depending on the fungal species. Additionally, it contained kefir microorganisms at levels of 1 × 10(8) colony-forming units (CFU) kg(-1) of lactic acid bacteria and 6 × 10(7) CFU kg(-1) of yeasts even after 30 days of storage. Fermented whey added to poultry feed acted as a biopreservative, improving its resistance to fungal contamination and increasing its shelf life. © 2014 Society of Chemical Industry.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, W.; Kan, A.T.; Fu, G.

Neutral organic contaminants commonly reside on the solid portion of soils and sediments. The extent of desorption from these solids determines the fate, reactivity, and toxicity. Numerous researchers have observed that, after an initial exposure of a few days, desorption takes place in two phases, namely, an initial rapid release followed by a long-term resistant phase. Resistant desorption has been highly unpredictable. In this research, the adsorption and desorption of chlorobenzenes, hexachlorobutadiene, and naphthalene have been studied using historically and freshly contaminated bayou sediments from Lake Charles, Louisiana, USA. After an initial release period, both laboratory-spiked and historically contaminated sedimentsmore » from Lake Charles, Louisiana, USA. After an initial release period, both laboratory-spiked and historically contaminated sediments exhibit similar desorption profiles. The simulations compare favorably with previous in situ measurements. All desorption results, both laboratory and field, could reasonably be interpreted using a single irreversible isotherm. Consequences of these results in terms of sediment quality criteria (SQC) are also discussed. Finally, an index of fractional irreversible adsorption is proposed and tested.« less
Effective personal protective clothing for health care workers attending patients with severe acute respiratory syndrome.

PubMed

Wong, Thomas K S; Chung, Joanne W Y; Li, Y; Chan, Wai F; Ching, Patricia T Y; Lam, Conita H S; Chow, Chun B; Seto, Wing H

2004-04-01

Optimal usability is crucial in providing protection for health care workers who are exposed to severe acute respiratory syndrome day and night while taking care of patients with the virus. No research study has yet tested the usability of personal protective clothing (PPC). The study was carried out in 3 stages. PPC available in Hong Kong were sorted by their physical properties in the first stage. The second stage was a single-blinded study examining the different usability aspects of the PPC. The third stage was a simulated viral load test. Four types were identified: good water repellency and water resistance, poor air permeability (Type A PPC); good water repellency and air permeability, poor water resistance (Type B PPC); poor water repellency, poor water resistance, and fair air permeability (Type C PPC); and good water repellency, poor air permeability, and fair water resistance (Type D PPC). Type D PPC had a significantly higher number of contamination sites on the subjects' dorsum and palm. Type C PPC had the highest contamination over the trunk. Findings in the viral load test showed that there was a significant difference in the contamination of the face (t=4.69, df=38, P<.00) between 1 and 2 strokes. Type A PPC is effective in providing a desirable protective function against droplet splash, if a disposable PPC is required. Type C PPC, the surgical gown, is also appropriate, as the cost is low, air permeability is fair, and the level of possible hand contamination is lowest among the 4 groups in the current study.
Integrated electromagnetic (EM) and Electrical Resistivity Tomography (ERT) geophysical studies of environmental impact of Awotan dumpsite in Ibadan, southwestern Nigeria

NASA Astrophysics Data System (ADS)

Osinowo, Olawale Olakunle; Falufosi, Michael Oluseyi; Omiyale, Eniola Oluwatosin

2018-04-01

This study attempts to establish the level of contamination caused by the decomposition of wastes by defining the lateral distribution and the vertical limit of leachate induced zone of anomalous conductivity distribution within the subsurface through the analyses of Electromagnetic (EM) and Electrical Resistivity Tomography (ERT) data, generated from the integrated geophysical survey over Awotan landfill dumpsite, in Ibadan, southwest Nigeria. Nine (9) EM and ERT profiles each were established within and around the Awotan landfill site. EM data were acquire at 5 m station interval using 10 m, 20 m and 40 m inter-coil spacings, while ERT stations were occupied at 2 m electrode spacing using dipole-dipole electrode configuration. The near perfect agreement between the two sets of data generated from the EM and ERT surveys over the Awotan landfill site as well as the subsurface imaging ability of these geophysical methods to delineate the region of elevated contamination presented in the form of anomalously high apparent ground conductivity and low subsurface resistivity distribution, suggest the importance of integrating electromagnetic and electrical resistivity investigation techniques for environmental studies and more importantly for selecting appropriate landfill dump site location such with ability to retain the generated contaminants and thus prevent environmental pollution.
Drinking Water from Dug Wells in Rural Ghana — Salmonella Contamination, Environmental Factors, and Genotypes

PubMed Central

Dekker, Denise Myriam; Krumkamp, Ralf; Sarpong, Nimako; Frickmann, Hagen; Boahen, Kennedy Gyau; Frimpong, Michael; Asare, Renate; Larbi, Richard; Hagen, Ralf Matthias; Poppert, Sven; Rabsch, Wolfgang; Marks, Florian; Adu-Sarkodie, Yaw; May, Jürgen

2015-01-01

Salmonellosis is an important but neglected disease in sub-Saharan Africa. Food or fecal-oral associated transmissions are the primary cause of infections, while the role of waterborne transmission is unclear. Samples were collected from different dug wells in a rural area of Ghana and analyzed for contamination with bacteria, and with Salmonella in particular. In addition, temporal dynamics and riks factors for contamination were investigated in 16 wells. For all Salmonella isolates antibiotic susceptibility testing was performed, serovars were determined and strains from the same well with the same serovar were genotyped. The frequency of well water contamination with Gram-negative rod-shaped bacteria was 99.2% (n = 395). Out of 398 samples, 26 (6.5%) tested positive for Salmonella spp. The serovar distribution was diverse including strains not commonly isolated from clinical samples. Resistance to locally applied antibiotics or resistance to fluoroquinolones was not seen in the Salmonella isolates. The risk of Salmonella contamination was lower in wells surrounded by a frame and higher during the rainy season. The study confirms the overall poor microbiological quality of well water in a resource-poor area of Ghana. Well contamination with Salmonella poses a potential threat of infection, thus highlighting the important role of drinking water safety in infectious disease control. PMID:25826395
Muddying the Waters: A New Area of Concern for Drinking Water Contamination in Cameroon

PubMed Central

Healy Profitós, Jessica M.; Mouhaman, Arabi; Lee, Seungjun; Garabed, Rebecca; Moritz, Mark; Piperata, Barbara; Tien, Joe; Bisesi, Michael; Lee, Jiyoung

2014-01-01

In urban Maroua, Cameroon, improved drinking water sources are available to a large majority of the population, yet this water is frequently distributed through informal distribution systems and stored in home containers (canaries), leaving it vulnerable to contamination. We assessed where contamination occurs within the distribution system, determined potential sources of environmental contamination, and investigated potential pathogens. Gastrointestinal health status (785 individuals) was collected via health surveys. Drinking water samples were collected from drinking water sources and canaries. Escherichia coli and total coliform levels were evaluated and molecular detection was performed to measure human-associated faecal marker, HF183; tetracycline-resistance gene, tetQ; Campylobacter spp.; and Staphylococcus aureus. Statistical analyses were performed to evaluate the relationship between microbial contamination and gastrointestinal illness. Canari samples had higher levels of contamination than source samples. HF183 and tetQ were detected in home and source samples. An inverse relationship was found between tetQ and E. coli. Presence of tetQ with lower E. coli levels increased the odds of reported diarrhoeal illness than E. coli levels alone. Further work is warranted to better assess the relationship between antimicrobial-resistant bacteria and other pathogens in micro-ecosystems within canaries and this relationship’s impact on drinking water quality. PMID:25464137
Muddying the waters: a new area of concern for drinking water contamination in Cameroon.

PubMed

Profitós, Jessica M Healy; Mouhaman, Arabi; Lee, Seungjun; Garabed, Rebecca; Moritz, Mark; Piperata, Barbara; Tien, Joe; Bisesi, Michael; Lee, Jiyoung

2014-11-28

In urban Maroua, Cameroon, improved drinking water sources are available to a large majority of the population, yet this water is frequently distributed through informal distribution systems and stored in home containers (canaries), leaving it vulnerable to contamination. We assessed where contamination occurs within the distribution system, determined potential sources of environmental contamination, and investigated potential pathogens. Gastrointestinal health status (785 individuals) was collected via health surveys. Drinking water samples were collected from drinking water sources and canaries. Escherichia coli and total coliform levels were evaluated and molecular detection was performed to measure human-associated faecal marker, HF183; tetracycline-resistance gene, tetQ; Campylobacter spp.; and Staphylococcus aureus. Statistical analyses were performed to evaluate the relationship between microbial contamination and gastrointestinal illness. Canari samples had higher levels of contamination than source samples. HF183 and tetQ were detected in home and source samples. An inverse relationship was found between tetQ and E. coli. Presence of tetQ with lower E. coli levels increased the odds of reported diarrhoeal illness than E. coli levels alone. Further work is warranted to better assess the relationship between antimicrobial-resistant bacteria and other pathogens in micro-ecosystems within canaries and this relationship's impact on drinking water quality.
Drinking water from dug wells in rural ghana--salmonella contamination, environmental factors, and genotypes.

PubMed

Dekker, Denise Myriam; Krumkamp, Ralf; Sarpong, Nimako; Frickmann, Hagen; Boahen, Kennedy Gyau; Frimpong, Michael; Asare, Renate; Larbi, Richard; Hagen, Ralf Matthias; Poppert, Sven; Rabsch, Wolfgang; Marks, Florian; Adu-Sarkodie, Yaw; May, Jürgen

2015-03-27

Salmonellosis is an important but neglected disease in sub-Saharan Africa. Food or fecal-oral associated transmissions are the primary cause of infections, while the role of waterborne transmission is unclear. Samples were collected from different dug wells in a rural area of Ghana and analyzed for contamination with bacteria, and with Salmonella in particular. In addition, temporal dynamics and riks factors for contamination were investigated in 16 wells. For all Salmonella isolates antibiotic susceptibility testing was performed, serovars were determined and strains from the same well with the same serovar were genotyped. The frequency of well water contamination with Gram-negative rod-shaped bacteria was 99.2% (n = 395). Out of 398 samples, 26 (6.5%) tested positive for Salmonella spp. The serovar distribution was diverse including strains not commonly isolated from clinical samples. Resistance to locally applied antibiotics or resistance to fluoroquinolones was not seen in the Salmonella isolates. The risk of Salmonella contamination was lower in wells surrounded by a frame and higher during the rainy season. The study confirms the overall poor microbiological quality of well water in a resource-poor area of Ghana. Well contamination with Salmonella poses a potential threat of infection, thus highlighting the important role of drinking water safety in infectious disease control.
Responses of Oat Grains to Fusarium poae and F. langsethiae Infections and Mycotoxin Contaminations

PubMed Central

Martin, Charlotte; Schöneberg, Torsten; Morisoli, Romina; Bertossa, Mario; Bucheli, Thomas D.; Mauch-Mani, Brigitte; Mascher, Fabio

2018-01-01

Recent increases of Fusarium head blight (FHB) disease caused by infections with F. poae (FP) and F. langsethiae (FL) have been observed in oats. These pathogens are producers of nivalenol (NIV) and T-2/HT-2 toxin (T-2/HT-2), respectively, which are now considered major issues for cereal food and feed safety. To date, the impact of FP and FL on oat grains has not yet been identified, and little is known about oat resistance elements against these pathogens. In the present study, the impact of FL and FP on oat grains was assessed under different environmental conditions in field experiments with artificial inoculations. The severity of FP and FL infection on grains were compared across three field sites, and the resistance against NIV and T-2/HT2 accumulation was assessed for seven oat genotypes. Grain weight, β-glucan content, and protein content were compared between infected and non-infected grains. Analyses of grain infection showed that FL was able to cause infection on the grain only in the field site with the highest relative humidity, whereas FP infected grains in all field sites. The FP infection of grains resulted in NIV contamination (between 30–500 μg/kg). The concentration of NIV in grains was not conditioned by environmental conditions. FL provoked an average contamination of grains with T-2/HT-2 (between 15–132 μg/kg). None of the genotypes was able to fully avoid toxin accumulation. The general resistance of oat grains against toxin accumulation was weak, and resistance against NIV accumulation was strongly impacted by the interaction between the genotype and the environment. Only the genotype with hull-less grains showed partial resistance to both NIV and T-2/HT-2 contamination. FP and FL infections could change the β-glucan content in grains, depending on the genotypes and environmental conditions. FP and FL did not have a significant impact on the thousand kernel weight (TKW) and protein content. Hence, resistance against toxin accumulation remains the only indicator of FHB resistance in oat. Our results highlight the need for new oat genotypes with enhanced resistance against both NIV and T-2/HT-2 to ensure food and feed safety. PMID:29361693
Airborne bacterial contaminations in typical Chinese wet market with live poultry trade.

PubMed

Gao, Xin-Lei; Shao, Ming-Fei; Luo, Yi; Dong, Yu-Fang; Ouyang, Feng; Dong, Wen-Yi; Li, Ji

2016-12-01

Chinese wet markets with live poultry trade have been considered as major sources of pathogen dissemination, and sites for horizontal transfer of bacterial and viral pathogens. In this study, the pathogenic bacteria and antibiotic resistant genes (ARGs) in air samples collected at a typical Chinese wet market had been analysis and quantified. Corynebacterium minutissimum and other pathogenic bacteria accounted for 0.81-8.02% of the whole microbial community in different air samples. The four ARGs quantified in this study showed a comparable relative concentration (copies/ng_DNA) with municipal wastewater. Poultry manures were demonstrated to be important microbial contamination source in wet market, which was supported by both microbial composition based source tracking and the quantification of airborne microbial density. A series of Firmicutes and Bacteroidetes indicators of poultry area contamination were successfully screened, which will be useful for the more convenient monitoring of airborne poultry area contamination. Our results indicate bioaerosols acted as important route for the transmissions of pathogens and ARGs. Continued surveillance of airborne microbial contamination is required in poultry trade wet market. Urban live poultry markets are important sources of pathogen dissemination, and sites for horizontal transfer of viral and bacterial pathogens. In the present field-study, pathogenic bacteria and antibiotic resistance genes were focused to provide quantitative information on the levels of microbial contaminations at the indoor air of wet markets. Results demonstrated that poultry manures were important microbial contamination source in wet market, and in the meanwhile bioaerosols were identified as important route for the transmissions of microbial contaminants. A series of Firmicutes and Bacteroidetes indicators of poultry area contamination were successfully screened, which will be useful for the more convenient monitoring of airborne poultry area contamination. Copyright © 2016 Elsevier B.V. All rights reserved.
Short communication: Characterization of methicillin-resistant Staphylococcus aureus isolated from raw milk fresh cheese in Colombia.

PubMed

Herrera, Fanny C; García-López, María-Luisa; Santos, Jesús A

2016-10-01

The aim of this study was the characterization of a collection of 8 methicillin-resistant Staphylococcus aureus (MRSA) isolates, obtained from samples of fresh cheese (Doble Crema) produced from raw cow milk in small dairies in Colombia. All the isolates harbored the mecA and Panton-Valentine leukocidin (PVL) genes, presented with SCCmec type IV, and belonged to multilocus sequence type 8 and spa type 024. Seven isolates presented 3 closely related pulsed-field gel electrophoresis profiles. Three of them carried the staphylococcal enterotoxin B gene. The isolates were resistant to cefoxitin, oxacillin, penicillin, and ampicillin and susceptible to all non-β-lactams antibiotics tested, with minimum inhibitory concentration values for oxacillin of 4 to 8mg/L. The isolates belonged to the community-acquired MRSA group, suggesting a human source of contamination. The risk of human infection by MRSA via contaminated foods is considered low, but contaminated food commodities can contribute to the worldwide dissemination of clones of community-acquired MRSA. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
Fungi associated with drug recalls and rare disease outbreaks.

PubMed

Ahearn, Donald G; Doyle Stulting, R

2014-11-01

Fungi rarely cause disease outbreaks associated with use of microbe-contaminated drugs. These rare episodes typically involve a restricted spectrum of common environmental species with relatively low virulence, rather than classical pathogens. Review of data involving over-the-counter contact lens solutions and prescription drug-related recalls revealed six episodes during the past decade with significant adverse health and financial impact (including loss of vision and death). Contaminations involved fungi mostly identified with the genera Aspergillus, Exserohilum, Fusarium, Paecilomyces, and Rhizopus. These organisms are noted for their capacity to produce resistant morphotypes (chlamydoconidia, ascospores) under various adverse conditions, generally with temperature survival/tolerances markedly in excess of maximal growth temperatures. High constituent levels of melanin, trehalose and heat-shock proteins facilitate differential survival of morphotypes following exposures to toxic chemicals and temperatures above 80 °C. Adverse environmental factors that induce resistant morphotypes are suggested to occur more readily in situ than during in vitro testing. Rare unexplained, sporadic drug contamination episodes with select thermotolerant fungi may relate, in part, to resistant dormant stages.
ALGE3D: A Three-Dimensional Transport Model

NASA Astrophysics Data System (ADS)

Maze, G. M.

2017-12-01

Of the top 10 most populated US cities from a 2015 US Census Bureau estimate, 7 of the cities are situated near the ocean, a bay, or on one of the Great Lakes. A contamination of the water ways in the United States could be devastating to the economy (through tourism and industries such as fishing), public health (from direct contact, or contaminated drinking water), and in some cases even infrastructure (water treatment plants). Current national response models employed by emergency response agencies have well developed models to simulate the effects of hazardous contaminants in riverine systems that are primarily driven by one-dimensional flows; however in more complex systems, such as tidal estuaries, bays, or lakes, a more complex model is needed. While many models exist, none are capable of quick deployment in emergency situations that could contain a variety of release situations including a mixture of both particulate and dissolved chemicals in a complex flow area. ALGE3D, developed at the Department of Energy's (DOE) Savannah River National Laboratory (SRNL), is a three-dimensional hydrodynamic code which solves the momentum, mass, and energy conservation equations to predict the movement and dissipation of thermal or dissolved chemical plumes discharged into cooling lakes, rivers, and estuaries. ALGE3D is capable of modeling very complex flows, including areas with tidal flows which include wetting and drying of land. Recent upgrades have increased the capabilities including the transport of particulate tracers, allowing for more complete modeling of the transport of pollutants. In addition the model is capable of coupling with a one-dimension riverine transport model or a two-dimension atmospheric deposition model in the event that a contamination event occurs upstream or upwind of the water body.
Revealing potential functions of VBNC bacteria in polycyclic aromatic hydrocarbons biodegradation.

PubMed

Su, X M; Bamba, A M; Zhang, S; Zhang, Y G; Hashmi, M Z; Lin, H J; Ding, L X

2018-04-01

The bioremediation of polycyclic aromatic hydrocarbon (PAH)-contaminated sites is not running smoothly, because of the lower activity of PAH-degrading bacteria in actual bioremediation applications. The phenomenon of "viable but nonculturable" (VBNC) state may be a main limiting factor for their poor biodegradation capabilities of PAHs. Due to their abilities of entering into the VBNC state, most of bacterial populations with PAH-degradation potential remain unculturable. Resuscitation of VBNC bacteria will enhance the degradation capability of indigenous bacteria which will eventually obtain their better capabilities in environmental bioremediation. Although evidences have been presented indicating that resuscitation of VBNC bacteria in polychlorinated biphenyl (PCB)-contaminated environments not only significantly enhanced PCB degradation, but also obtained novel highly efficient PCB-degrading bacteria, scanty information is available on the VBNC bacteria in PAH-contaminated sites. VBNC bacteria, as a vast majority of potential microbial resource could be the repository of novel highly efficient PAH-biodegraders. Therefore, studies need to be done on resuscitation of VBNC bacteria to overcome key bottlenecks in bioremediation of PAH-contaminated sites. This mini-review provides a new insight into the potential functions of VBNC bacteria in PAHs biodegradation. As the vast majority microbial resource, viable but nonculturable (VBNC) bacteria, which showed their potential functions in polycyclic aromatic hydrocarbons (PAHs) biodegradation, can be of great significance in environmental bioremediation. It is therefore important to resuscitate VBNC bacteria for their better capabilities. Meanwhile, preventing the indigenous functional community from entering into the VBNC state will also maintain the high activity of PAH-degrading bacteria in actual bioremediation applications. Undoubtedly, much more work needs to be done to reveal indigenous micro-organisms in the VBNC state from the perspective of environmental functions. © 2018 The Society for Applied Microbiology.
Airborne chemical contamination of a chemically amplified resist

NASA Astrophysics Data System (ADS)

MacDonald, Scott A.; Clecak, Nicholas J.; Wendt, H. R.; Willson, C. Grant; Snyder, Clinton D.; Knors, C. J.; Deyoe, N. B.; Maltabes, John G.; Morrow, James R.; McGuire, Anne E.; Holmes, Steven J.

1991-06-01

We have found that the performance of the t-BOC/onium salt resist system is severely degraded by vapor from organic bases. This effect is very pronounced and can be observed when the coated wafers stand for 15 minutes in air containing as little as 15 parts per billion (ppb) of an organic base. The observed effect, caused by this chemical contamination, depends on the tone of the resist system. For negative tone systems the UV exposure dose, required to obtain the correct linewidth, increases. While for the positive tone system, one observes the generation of a skin at the resist-air interface. Both effects are caused by the photogenerated acid being neutralized by the airborne organic base. There are a wide variety of commonly used materials which can liberate trace amounts of volatile amines and degrade resist performance. For example, fresh paint on a laboratory wall can exhibit this detrimental effect. These effects can be minimized by storing and processing the resist coated wafers in air that has passed through a specially designed, high efficiency carbon filter. The implementation of localized air filtration, to bathe the resist in chemically pure air, enabled this resist system to operate in a manufacturing environment at a rate of 100 wafers/hour.
Surfactant/Supercritical Fluid Cleaning of Contaminated Substrates

NASA Technical Reports Server (NTRS)

White, Gary L.

1997-01-01

CFC's and halogenated hydrocarbon solvents have been the solvents of choice to degrease and otherwise clean precision metal parts to allow proper function. Recent regulations have, however, rendered most of these solvents unacceptable for these purposes. New processes which are being used or which have been proposed to replace these solvents usually either fail to remove water soluble contaminants or produce significant aqueous wastes which must then be disposed of. In this work, a new method for cleaning surfaces will be investigated. Solubility of typical contaminants such as lubricating greases and phosphatizing bath residues will be studied in several surfactant/supercritical fluid solutions. The effect of temperature, pressure, and the composition of the cleaning mixture on the solubility of oily, polar, and ionic contaminants will be investigated. A reverse micellar solution in a supercritical light hydrocarbon solvent will be used to clean samples of industrial wastes. A reverse micellar solution is one where water is dissolved into a non-polar solvent with the aid of a surfactant. The solution will be capable of dissolving both water-soluble contaminants and oil soluble contaminants. Once the contaminants have been dissolved into the solution they will be separated from the light hydrocarbon and precipitated by a relatively small pressure drop and the supercritical solvent will be available for recycle for reuse. The process will be compared to the efficacy of supercritical CO2 cleaning by attempting to clean the same types of substrates and machining wastes with the same contaminants using supercritical CO2. It is anticipated that the supercritical CO2 process will not be capable of removing ionic residues.

Transgenic expression of a maize geranyl geranyl transferase gene sequence in maize callus increases resistance to ear rot pathogens

USDA-ARS?s Scientific Manuscript database

Determining the genes responsible for pest resistance in maize can allow breeders to develop varieties with lower losses and less contamination with undesirable toxins. A gene sequence coding for a geranyl geranyl transferase-like protein located in a fungal ear rot resistance quantitative trait loc...
Characterization of the chitinase gene family and the effect on A. flavus and aflatoxin resistance in maize.

USDA-ARS?s Scientific Manuscript database

Maize (Zea mays L.) is a crop of global importance, but is prone to contamination by aflatoxins produced by fungi in the genus Aspergillus. The development of resistant germplasm and the identification of genes contributing to resistance would aid in the reduction of the problem with a minimal need ...
IN SITU APPARENT CONDUCTIVITY MEASUREMENTS AND MICROBIAL POPULATION DISTRIBUTION AT A HYDROCARBON CONTAMINATED SITE

EPA Science Inventory

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

EPA Science Inventory

Introduction and large-scale production of synthetic halogenated organic chemicals over the last fifty years has resulted in a group of contaminants that tend to persist in the environment and resist both biotic and abiotic degradation. The low solubility of these types of contam...
Isolation and characterization of a virulent bacteriophage SPW specific for Staphylococcus aureus isolated from bovine mastitis of lactating dairy cattle.

PubMed

Li, Longping; Zhang, Zhiying

2014-09-01

Mastitis in dairy cattle continues to be an economically important disease. However, control is complicated by a high prevalence of resistance to antibiotics. Phage therapy, therefore, is considered as an alternative way of controlling bacterial infections and contaminations. In this study, we have described isolation and characterization of a highly virulent phage SPW from wastewater of dairy farm, which possesses a strong lytic capability against mastitis-associated Staphylococcus aureus, the most important pathogen in bovine clinical and subclinical mastitis. The phage SPW produced large, round and clear plaques on bacterial culture plates. TEM showed phage SPW has an icosahedral head 62.5 nm in diameter and long tail of 106 nm, head and tail were held together by a connector of 18 ± 1.5 nm long and can be classified as a member of the Myoviridae family. Restriction analysis indicated that phage SPW was a dsDNA virus with an approximate genome size of 65-69 kb. One-step growth kinetics showed a short latency period of about 10-15 min and a rise period of 50 min and a relatively small burst size was 44 ± 3 phages particles/infected cell. Moreover, adsorption rates were not influenced by calcium ions and phage SPW was relatively stable in a wide range of temperature and pH values, and resistant to chloroform and isopropanol. The optimal multiplicity of infection (MOI) was 0.01. When phage SPW was used to infect five other clinically isolated pathogenic isolates, it showed relatively wide spectrum host range. Phage SPW was capable of eliciting efficient lysis of S. aureus, revealing it potentially as an effective approach to prophylaxis or treatment of S. aureus-associated mastitis in dairy cows.
Bioremediation of contaminated groundwater

DOEpatents

Hazen, T.C.; Fliermans, C.B.

1994-01-01

Disclosed is an apparatus and method for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid (NF) is selected to simulated the growth and reproduction of indigenous subsurface microorganisms capable of degrading the contaminants; an oxygenated fluid (OF) is selected to create an aerobic environment with anaerobic pockets. NF is injected periodically while OF is injected continuously and both are extracted so that both are drawn across the plume. NF stimulates microbial colony growth; withholding it periodically forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is acceptable. NF can be methane and OF be air, for stimulating production of methanotrophs to break down chlorohydrocarbons, especially TCE and tetrachloroethylene.
Evaluation of copper resistant bacteria from vineyard soils and mining waste for copper biosorption

PubMed Central

Andreazza, R.; Pieniz, S.; Okeke, B.C.; Camargo, F.A.O

2011-01-01

Vineyard soils are frequently polluted with high concentrations of copper due application of copper sulfate in order to control fungal diseases. Bioremediation is an efficient process for the treatment of contaminated sites. Efficient copper sorption bacteria can be used for bioremoval of copper from contaminated sites. In this study, a total of 106 copper resistant bacteria were examined for resistance to copper toxicity and biosorption of copper. Eighty isolates (45 from vineyard Mollisol, 35 from Inceptisol) were obtained from EMBRAPA (Empresa Brasileira de Pesquisa Agropecuária) experimental station, Bento Gonçalves, RS, Brazil (29°09′53.92″S and 51°31′39.40″W) and 26 were obtained from copper mining waste from Caçapava do Sul, RS, Brazil (30°29′43.48″S and 53′32′37.87W). Based on resistance to copper toxicity and biosorption, 15 isolates were identified by 16S rRNA gene sequencing. Maximal copper resistance and biosorption at high copper concentration were observed with isolate N2 which removed 80 mg L−1 in 24 h. Contrarily isolate N11 (Bacillus pumilus) displayed the highest specific copper biosorption (121.82 mg/L/OD unit in 24 h). GenBank MEGABLAST analysis revealed that isolate N2 is 99% similar to Staphylococcus pasteuri. Results indicate that several of our isolates have potential use for bioremediation treatment of vineyards soils and mining waste contaminated with high copper concentration. PMID:24031606
High Prevalence of Multidrug-Resistant Community-Acquired Methicillin-Resistant Staphylococcus aureus at the Largest Veterinary Teaching Hospital in Costa Rica.

PubMed

Rojas, Irene; Barquero-Calvo, Elías; van Balen, Joany C; Rojas, Norman; Muñoz-Vargas, Lohendy; Hoet, Armando E

2017-09-01

Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen associated with severe infections in companion animals present in the community, and it is diagnosed in animals admitted to veterinary hospitals. However, reports that describe the circulation of MRSA in animal populations and veterinary settings in Latin America are scarce. Therefore, the objective of this study was to determine the prevalence and investigate the molecular epidemiology of MRSA in the environment of the largest veterinary teaching hospital in Costa Rica. Preselected contact surfaces were sampled twice within a 6-week period. Antimicrobial resistance, SCCmec type, Panton-Valentine leukocidin screening, USA type, and clonality were assessed in all recovered isolates. Overall, MRSA was isolated from 26.5% (27/102) of the surfaces sampled, with doors, desks, and examination tables most frequently contaminated. Molecular analysis demonstrated a variety of surfaces from different sections of the hospital contaminated by three highly related clones/pulsotypes. All, but one of the isolates were characterized as multidrug-resistant SCCmec type IV-USA700, a strain sporadically described in other countries and often classified as community acquired. The detection and frequency of this unique strain in this veterinary setting suggest Costa Rica has a distinctive MRSA ecology when compared with other countries/regions. The high level of environmental contamination highlights the necessity to establish and enforce standard cleaning and disinfection protocols to minimize further spread of this pathogen and reduce the risk of nosocomial and/or occupational transmission of MRSA.
Preliminary Investigation of Paleochannels and Groundwater Specific Conductance using Direct-Current Resistivity and Surface-Wave Seismic Geophysical Surveys at the Standard Chlorine of Delaware, Inc., Superfund Site, Delaware City, Delaware, 2008

USGS Publications Warehouse

Degnan, James R.; Brayton, Michael J.

2010-01-01

The U.S. Geological Survey (USGS), in cooperation with Region III of the U.S. Environmental Protection Agency (USEPA) and the State of Delaware, is conducting an ongoing study of the water-quality and hydrogeologic properties of the Columbia and Potomac aquifers and the extent of cross-aquifer contamination with benzene; chlorobenzene; 1,2-dichlorobenzene; 1,4-dichlorobenzene; and hydrogen chloride (hydrochloric acid when dissolved in water) in the vicinity of the Standard Chlorine of Delaware, Inc. (SCD), Superfund Site, Delaware City, Delaware. Surface geophysical surveys and well data were used to identify and correlate low-permeability units (clays) across the site and to search for sand and gravel filled paleochannels that are potential conduits and receptors of contaminated groundwater and (or) Dense Non-Aqueous Phase Liquid (DNAPL) contaminants. The combined surveys and well data were also used to characterize areas of the site that have groundwater with elevated (greater than 1,000 microsiemens per centimeter) specific conductance (SC) as a result of contamination. The most electrically conductive features measured with direct-current (DC) resistivity at the SCD site are relatively impermeable clays and permeable sediment that are associated with elevated SC in groundwater. Many of the resistive features include paleochannel deposits consisting of coarse-grained sediments that are unsaturated, have low (less than 200 microsiemens per centimeter) SC pore water, or are cemented. Groundwater in uncontaminated parts of the Columbia aquifer and of the Potomac aquifer has a low SC. Specific-conductance data from monitoring wells at the site were used to corroborate the DC-resistivity survey results. For comparison with DC-resistivity surveys, multi-channel analysis of surface wave (MASW) surveys were used and were able to penetrate deep enough to measure the Columbia aquifer, which is known to have elevated SC in some places. MASW survey results respond to solid material stiffness; clays and cemented sediments will have a higher velocity than silts, sands, and gravels (in order of increasing hydraulic conductivity). Geophysical surveys detected elevated SC associated with contamination of the surficial Columbia aquifer. Groundwater with elevated SC over ambient (by an order of magnitude) produced a decrease in measured resistivity at the SCD site. Where SC data are not available from wells, it is not known if a low resistivity value measured with DC resistivity alone results from the geologic material (clay) or elevated SC in groundwater (in sand or gravel). Seismic surface waves used as part of the MASW technique are not affected by water content or quality and are used herein to distinguish between sand and clay when SC is high. Through concurrent interpretation of MASW and DC-resistivity surveys, information was gained about water quality and lithology over large areas at the SCD site.
Effects of corresponding and non-corresponding contaminants on the fate of sulfonamide and quinolone resistance genes in the Laizhou Bay, China.

PubMed

Li, Qianwei; Na, Guangshui; Zhang, Linxiao; Lu, Zihao; Gao, Hui; Li, Ruijing; Jin, Shuaichen

2018-03-01

The environmental behaviors and migration patterns of antibiotic resistance genes (ARGs) have attracted considerable research interest. However, there has been little research concerning the effects of corresponding and non-corresponding contaminants on the fate of ARGs in coastal environments. In the present study, the distribution of intI1, sul1, sul2, qnrS and aac(6')-Ib were analyzed in water and sediment samples of Laizhou Bay in the context of corresponding and non-corresponding contaminants. The abundance of intI1, sul1 and sul2 genes exhibited a clear decreasing trend extending from the inner estuary to the coastal area. Strong and positive correlations existed between sul1/sul2 and sulfonamide antibiotic residues in sediments, and between the abundances of intI1 and sul1/sul2. Statistical analyses indicated that non-corresponding contaminants were partially correlated with ARG abundances. These results suggest that non-corresponding contaminants may have direct or indirect influences on the abundances of ARGs and intI1 in the Laizhou Bay. Copyright © 2018 Elsevier Ltd. All rights reserved.
Metal resistant plants and phytoremediation of environmental contamination

DOEpatents

Meagher, Richard B.; Li, Yujing; Dhankher, Om P.

2010-04-20

The present disclosure provides a method of producing transgenic plants which are resistant to at least one metal ion by transforming the plant with a recombinant DNA comprising a nucleic acid encoding a bacterial arsenic reductase under the control of a plant expressible promoter, and a nucleic acid encoding a nucleotide sequence encoding a phytochelatin biosynthetic enzyme under the control of a plant expressible promoter. The invention also relates a method of phytoremediation of a contaminated site by growing in the site a transgenic plant expressing a nucleic acid encoding a bacterial arsenate reductase and a nucleic acid encoding a phytochelatin biosynthetic enzyme.
Meta-transcriptomics indicates biotic cross-tolerance in willow trees cultivated on petroleum hydrocarbon contaminated soil.

PubMed

Gonzalez, Emmanuel; Brereton, Nicholas J B; Marleau, Julie; Guidi Nissim, Werther; Labrecque, Michel; Pitre, Frederic E; Joly, Simon

2015-10-12

High concentrations of petroleum hydrocarbon (PHC) pollution can be hazardous to human health and leave soils incapable of supporting agricultural crops. A cheap solution, which can help restore biodiversity and bring land back to productivity, is cultivation of high biomass yielding willow trees. However, the genetic mechanisms which allow these fast-growing trees to tolerate PHCs are as yet unclear. Salix purpurea 'Fish Creek' trees were pot-grown in soil from a former petroleum refinery, either lacking or enriched with C10-C50 PHCs. De novo assembled transcriptomes were compared between tree organs and impartially annotated without a priori constraint to any organism. Over 45% of differentially expressed genes originated from foreign organisms, the majority from the two-spotted spidermite, Tetranychus urticae. Over 99% of T. urticae transcripts were differentially expressed with greater abundance in non-contaminated trees. Plant transcripts involved in the polypropanoid pathway, including phenylalanine ammonia-lyase (PAL), had greater expression in contaminated trees whereas most resistance genes showed higher expression in non-contaminated trees. The impartial approach to annotation of the de novo transcriptomes, allowing for the possibility for multiple species identification, was essential for interpretation of the crop's response treatment. The meta-transcriptomic pattern of expression suggests a cross-tolerance mechanism whereby abiotic stress resistance systems provide improved biotic resistance. These findings highlight a valuable but complex biotic and abiotic stress response to real-world, multidimensional contamination which could, in part, help explain why crops such as willow can produce uniquely high biomass yields on challenging marginal land.
Lateral Gene Transfer in a Heavy Metal-Contaminated-Groundwater Microbial Community

PubMed Central

Hemme, Christopher L.; Green, Stefan J.; Rishishwar, Lavanya; Prakash, Om; Pettenato, Angelica; Chakraborty, Romy; Deutschbauer, Adam M.; Van Nostrand, Joy D.; Wu, Liyou; He, Zhili; Jordan, I. King; Arkin, Adam P.; Kostka, Joel E.

2016-01-01

ABSTRACT Unraveling the drivers controlling the response and adaptation of biological communities to environmental change, especially anthropogenic activities, is a central but poorly understood issue in ecology and evolution. Comparative genomics studies suggest that lateral gene transfer (LGT) is a major force driving microbial genome evolution, but its role in the evolution of microbial communities remains elusive. To delineate the importance of LGT in mediating the response of a groundwater microbial community to heavy metal contamination, representative Rhodanobacter reference genomes were sequenced and compared to shotgun metagenome sequences. 16S rRNA gene-based amplicon sequence analysis indicated that Rhodanobacter populations were highly abundant in contaminated wells with low pHs and high levels of nitrate and heavy metals but remained rare in the uncontaminated wells. Sequence comparisons revealed that multiple geochemically important genes, including genes encoding Fe2+/Pb2+ permeases, most denitrification enzymes, and cytochrome c553, were native to Rhodanobacter and not subjected to LGT. In contrast, the Rhodanobacter pangenome contained a recombinational hot spot in which numerous metal resistance genes were subjected to LGT and/or duplication. In particular, Co2+/Zn2+/Cd2+ efflux and mercuric resistance operon genes appeared to be highly mobile within Rhodanobacter populations. Evidence of multiple duplications of a mercuric resistance operon common to most Rhodanobacter strains was also observed. Collectively, our analyses indicated the importance of LGT during the evolution of groundwater microbial communities in response to heavy metal contamination, and a conceptual model was developed to display such adaptive evolutionary processes for explaining the extreme dominance of Rhodanobacter populations in the contaminated groundwater microbiome. PMID:27048805
Potential of houseflies to contaminate ready-to-eat food with antibiotic-resistant enterococci.

PubMed

Macovei, Lilia; Miles, Brett; Zurek, Ludek

2008-02-01

It was shown previously that houseflies in fast-food restaurants commonly carry antibiotic-resistant and potentially virulent enterococci. In this study, the potential of field-collected houseflies to contaminate ready-to-eat (RTE) food with enterococci was assessed by laboratory bioassays. Houseflies were collected with a sweep net in a cattle feedlot and exposed in groups of 5, 10, 20, and 40 to a beef patty (from an RTE hamburger) for 0.5, 1.0, 3.0, and 24 h. The exposure of RTE food to flies resulted in 100% contamination with enterococci in all bioassays, regardless of the number of houseflies and the length of exposure time. In addition, with the increasing number of houseflies as well as with the increasing time exposure, the concentration of enterococci in RTE food increased. Even a short time exposure (0.5 h) resulted in food contamination, ranging from 3.1 x 10(3) CFU/g (5 houseflies) to 8.4 x 10(4) CFU/g (40 houseflies). The analysis of 23 randomly selected enterococcal isolates from RTE food after the fly exposure revealed a single species, Enterococcus faecalis. In contrast, four Enterococcus species, including E. faecalis (57.1%), E. gallinarum (19.1%), E. hirae (14.3%), and E. faecium (9.5%), represented 21 randomly selected and identified isolates from houseflies. Phenotypic screening showed that E. faecalis isolates from RTE food were resistant to ciprofloxacin (17.4%), tetracycline (13.0%), erythromycin (13.0%), and chloramphenicol (4.3%). This study demonstrates a great potential of houseflies from a cattle feedlot to contaminate RTE food with enterococci in a short time.
Blast and Penetration Resistant Tactical Shelters

DTIC Science & Technology

1979-07-01

2. Hardened Wall Material Properties 32 3. S-280 Shelter Panal Properties 33 4. Results Zor Dynamic Response of Complete S-280 Shelters 32 £-". In...insulation from a -6501 low to a 120 0F high plus a solar heating load 7. Corrosion resistance including salt fog 8. Blackout capability 9. Fungus...65 0 F), high temperature (120 0 F) plus a solar heating (BTU) load. g. Corrosion resistance (salt fog). 19 h. Blackout capability. i. Fungus
Lack of CYP1A responsiveness in species inhabiting chronically contaminated habitats: two varieties of resistance?

PubMed

Brammell, Ben F; Price, David J; Birge, Wesley J; Elskus, Adria A

2013-03-01

Organisms chronically exposed to organic pollutants such as polychlorinated biphenyls (PCBs) can develop resistance to these chemicals, a condition associated with reduced inducibility of the biomarker enzyme cytochrome P450 1A (CYP1A). This study addresses the CYP1A response of members of the families Ictaluridae and Centrarchidae, two fish families found throughout much of the United States. We measured CYP1A expression, PCB body burdens, and conducted CYP1A challenge experiments in species from these families residing in the Town Branch/Mud River system (Logan County, KY, USA), a stream system historically contaminated with high levels of PCBs. Despite PCB concentrations in muscle tissue typically associated with elevated CYP1A (16.7 to 75.2μgPCB/g wet edible flesh), resident fish in the contaminated Town Branch/Mud River sites (yellow bullhead [Ameiurus natalis], green sunfish [Lepomis cyanellus], and spotted bass [Micropterus punctulatus]) had hepatic CYP1A activity levels similar to, rather than higher than, those in reference fish, suggesting reduced sensitivity to CYP1A induction. Lack of CYP1A expression following direct contaminant exposure has often been associated with resistance to those contaminants. To determine if CYP1A in resident populations was resistant to induction by PCBs, we exposed resident fish to a single, intraperitoneal injection with a potent CYP1A inducer, 3,4,3',4'-tetrachlorobiphenyl (PCB 77). PCB 77 treatment significantly induced hepatic CYP1A activity and protein in yellow bullhead from reference, but not contaminated, sites and had no effect on CYP1A in green sunfish from either site. The low CYP1A expression levels in resident fish with elevated PCB body burdens, together with the failure of PCB injection to induce CYP1A in certain populations, indicate an acclimatory CYP1A response in yellow bullheads and likely an inherently resistant CYP1A in green sunfish. This work demonstrates for the first time acclimation of CYP1A to PCBs in a species within the family Ictaluridae and provides further support for our previous work indicating an apparent inherent lack of CYP1A sensitivity to chlorinated inducers in Centrarchids. These traits may explain, at least in part, the common association of these families with degraded habitats and indicate Lepomis members are likely to be excellent candidates for exploring the mechanistic basis of 'inherent' CYP1A resistance. This study also underlines to the need for thorough characterization of the CYP1A responsivity of a population and/or species prior to using CYP1A as a reliable biomonitoring tool. Copyright © 2012. Published by Elsevier Inc.
Transcriptome Response to Heavy Metals in Sinorhizobium meliloti CCNWSX0020 Reveals New Metal Resistance Determinants That Also Promote Bioremediation by Medicago lupulina in Metal-Contaminated Soil.

PubMed

Lu, Mingmei; Jiao, Shuo; Gao, Enting; Song, Xiuyong; Li, Zhefei; Hao, Xiuli; Rensing, Christopher; Wei, Gehong

2017-10-15

The symbiosis of the highly metal-resistant Sinorhizobium meliloti CCNWSX0020 and Medicago lupulina has been considered an efficient tool for bioremediation of heavy metal-polluted soils. However, the metal resistance mechanisms of S. meliloti CCNWSX00200 have not been elucidated in detail. Here we employed a comparative transcriptome approach to analyze the defense mechanisms of S. meliloti CCNWSX00200 against Cu or Zn exposure. Six highly upregulated transcripts involved in Cu and Zn resistance were identified through deletion mutagenesis, including genes encoding a multicopper oxidase (CueO), an outer membrane protein (Omp), sulfite oxidoreductases (YedYZ), and three hypothetical proteins (a CusA-like protein, a FixH-like protein, and an unknown protein), and the corresponding mutant strains showed various degrees of sensitivity to multiple metals. The Cu-sensitive mutant (Δ cueO ) and three mutants that were both Cu and Zn sensitive (Δ yedYZ , Δ cusA -like, and Δ fixH -like) were selected for further study of the effects of these metal resistance determinants on bioremediation. The results showed that inoculation with the Δ cueO mutant severely inhibited infection establishment and nodulation of M. lupulina under Cu stress, while inoculation with the Δ yedYZ and Δ fixH -like mutants decreased just the early infection frequency and nodulation under Cu and Zn stresses. In contrast, inoculation with the Δ cusA -like mutant almost led to loss of the symbiotic capacity of M. lupulina to even grow in uncontaminated soil. Moreover, the antioxidant enzyme activity and metal accumulation in roots of M. lupulina inoculated with all mutants were lower than those with the wild-type strain. These results suggest that heavy metal resistance determinants may promote bioremediation by directly or indirectly influencing formation of the rhizobium-legume symbiosis. IMPORTANCE Rhizobium-legume symbiosis has been promoted as an appropriate tool for bioremediation of heavy metal-contaminated soils. Considering the plant-growth-promoting traits and survival advantage of metal-resistant rhizobia in contaminated environments, more heavy metal-resistant rhizobia and genetically manipulated strains were investigated. In view of the genetic diversity of metal resistance determinants in rhizobia, their effects on phytoremediation by the rhizobium-legume symbiosis must be different and depend on their specific assigned functions. Our work provides a better understanding of the mechanism of heavy metal resistance determinants involved in the rhizobium-legume symbiosis, and in further studies, genetically modified rhizobia harboring effective heavy metal resistance determinants may be engineered for the practical application of rhizobium-legume symbiosis for bioremediation in metal-contaminated soils. Copyright © 2017 American Society for Microbiology.
Uranium Interaction with Two Multi-Resistant Environmental Bacteria: Cupriavidus metallidurans CH34 and Rhodopseudomonas palustris

PubMed Central

Llorens, Isabelle; Untereiner, Guillaume; Jaillard, Danielle; Gouget, Barbara; Chapon, Virginie; Carriere, Marie

2012-01-01

Depending on speciation, U environmental contamination may be spread through the environment or inversely restrained to a limited area. Induction of U precipitation via biogenic or non-biogenic processes would reduce the dissemination of U contamination. To this aim U oxidation/reduction processes triggered by bacteria are presently intensively studied. Using X-ray absorption analysis, we describe in the present article the ability of Cupriavidus metallidurans CH34 and Rhodopseudomonas palustris, highly resistant to a variety of metals and metalloids or to organic pollutants, to withstand high concentrations of U and to immobilize it either through biosorption or through reduction to non-uraninite U(IV)-phosphate or U(IV)-carboxylate compounds. These bacterial strains are thus good candidates for U bioremediation strategies, particularly in the context of multi-pollutant or mixed-waste contaminations. PMID:23251623
[Capability of national reference laboratories in Latin America to detect emerging resistance mechanisms].

PubMed

Corso, Alejandra; Guerriero, Leonor; Pasterán, Fernando; Ceriana, Paola; Callejo, Raquel; Prieto, Mónica; Tuduri, Ezequiel; Lopardo, Horacio; Vay, Carlos; Smayevsky, Jorgelina; Tokumoto, Marta; Alvarez, Jorge Matheu; Pardo, Pilar Ramón; Galas, Marcelo

2011-12-01

To evaluate the capability of 17 national reference laboratories participating in the Latin American Quality Control Program in Bacteriology and Antibiotic Resistance (LA-EQAS) to detect emerging resistance mechanisms- namely: resistance of enterobacteria to carbapenems due to the presence of Klebsiella pneumoniae carbapenemase (KPC) and metallo-beta-lactamase (MBL) type IMP, and intermediate resistance of Staphylococcus aureus isolates to vancomycin (vancomycin-intermediate resistant S. aureus-VISA). The following three isolates were sent to the 17 participating LA-EQAS laboratories: KPC -producing Klebsiella pneumoniae PAHO-161, IMP-producing Enterobacter cloacae PAHO-166, and S. aureus PAHO-165 with intermediate resistance to vancomycin. Performance of each of the following operations was evaluated: interpretation of sensitivity tests, detection of the resistance mechanism, and assessment of either inhibition halo size (disk diffusion method) or minimum inhibitory concentration (MIC). Concordance in the detection of resistance mechanisms was 76.4%, 73.3%, and 66.7% for the K. pneumoniae PAHO-161, E. cloacae PAHO-166, and S. aureus PAHO-165 strains, respectively. Concordance between the inhibition areas observed by the participating laboratories and the ranges established by the coordinating laboratory was acceptable for all three isolates, at 90.8%, 92.8%, and 88.9%, respectively. Overall concordance in on the detection of KPC, MBL, and VISA resistance mechanisms was 72.1%. We consider the national reference laboratories in Latin America capable of recognizing these emerging resistance mechanisms and expect that maximum levels of concordance will be reached in the future.
FALLOUT DOSAGE AND MONITORING

PubMed Central

Kinsman, Simon

1960-01-01

At present there are a large number of people capable of conducting the task of surface and area radiation monitoring including external monitoring of personnel. Once the extent and the intensity of radioactivity in an area is determined, good use of personnel can be made without too much risk. This is fortunate for the medical profession whose personnel can devote their talents to casualty care during or following nuclear warfare. Most individuals who know how to detect and measure the extent of radioactive contamination are also capable of conducting personnel decontamination operations and would do so if necessary. Consequently the spread of contamination can be minimized by adequate decontamination and the medical personnel can treat casualties who are relatively free of external radioactive contamination. The appropriate use of trained manpower and radiation detection equipment which are available in California combined with sufficient rehearsals prior to a nuclear war will greatly reduce any casualty damage due to radioactive fallout. The chances of survival of individuals can be greatly improved with a little knowledge of protection from radioactive contamination and of salvage of food and water. PMID:14409247

COMPARISON OF SCANNING ELECTRON AND ATOMIC FORCE MICROSCOPY OF SURFACE FINISHES ON STAINLESS STEEL THAT REDUCE BACTERIAL ATTACHMENT

EPA Science Inventory

Bacteria adhere to food products and processing surfaces that can cross-contaminate other products and work surfaces (Arnold, 1998). Using materials for food processing surfaces that are resistant to bacterial contamination could enhance food safety. Stainless steel, although sus...
Biofilm formation, antimicrobial resistance, and sanitizer tolerance of Salmonella entericia strains isolated from beef trim

USDA-ARS?s Scientific Manuscript database

In the beef industry, product contamination by Salmonella enterica is a serious public health concern, which may result in human infection and cause significant financial loss due to product recalls. Currently, the precise mechanism and pathogen source responsible for Salmonella contamination in com...
Susceptibility of Pediococcus isolates to antimicrobial compounds in relation to hop-resistance and beer-spoilage.

PubMed

Haakensen, Monique; Vickers, David M; Ziola, Barry

2009-09-07

Though important in the context of food microbiology and as potential pathogens in immuno-compromised humans, bacterial isolates belonging to the genus Pediococcus are best known for their association with contamination of ethanol fermentation processes (beer, wine, or fuel ethanol). Use of antimicrobial compounds (e.g., hop-compounds, Penicillin) by some industries to combat Pediococcus contaminants is long-standing, yet knowledge about the resistance of pediococci to antimicrobial agents is minimal. Here we examined Pediococcus isolates to determine whether antibiotic resistance is associated with resistance to hops, presence of genes known to correlate with beer spoilage, or with ability to grow in beer. Lactic acid bacteria susceptibility test broth medium (LSM) used in combination with commercially available GPN3F antimicrobial susceptibility plates was an effective method for assessing antimicrobial susceptibility of Pediococcus isolates. We report the finding of Vancomycin-susceptible Pediococcus isolates from four species. Interestingly, we found that hop-resistant, beer-spoilage, and beer-spoilage gene-harbouring isolates had a tendency to be more susceptible, rather than more resistant, to antimicrobial compounds. Our findings indicate that the mechanisms involved in conferring hop-resistance or ability to spoil beer by Pediococcus isolates are not associated with resistance to antibiotics commonly used for treatment of human infections. Also, Vancomycin-resistance was found to be isolate-specific and not intrinsic to the genus as previously believed.
Genotypic and Phenotypic Characterization of Antimicrobial-Resistant Escherichia coli from Farm-Raised Diarrheic Sika Deer in Northeastern China

PubMed Central

Li, Rui; He, Liang; Hao, Lili; Wang, Qi; Zhou, Yu; Jiang, Hongchen

2013-01-01

In China, overuse and/or abuse of antimicrobials are common in stockbreeding, which possess high risks of antimicrobial-resistant contaminations. The serogroups, major virulence genes, and antimicrobial resistant patterns of the antimicrobial-resistant Escherichia coli (E. coli) were investigated in the feces of diarrheic farm-raised sika deer from 50 farms in three Northeastern provinces of China. A total of 220 E. coli isolates were obtained and characterized. Twenty-eight O serogroups were identified from the obtained E. coli isolates with O2, O26, O128, O142 and O154 being dominant. Nearly all the isolates were resistant to at least four of the tested antimicrobials. More than 90% of the E. coli isolates carried at least one of the tested virulence genes. About 85% of the E. coli isolates carried one or more antimicrobial-resistant genes responsible for resistant phenotypes of sulfonamides, streptomycin/spectionomycin or tetracycline. The antimicrobial resistant level and pathogenic group occurrences of the obtained E. coli isolates were higher than that of livestock and wild animals reported in some developed countries. Thus, the fecal-carrying antimicrobial-resistant E. coli from the farm-raised sika deer is potentially a significant contamination source for freshwater systems and food chain, and may pose great health risks for human and animals in Northeastern China. PMID:24039919
Residues of chlortetracycline, doxycycline and sulfadiazine-trimethoprim in intestinal content and feces of pigs due to cross-contamination of feed.

PubMed

Peeters, Laura E J; Daeseleire, Els; Devreese, Mathias; Rasschaert, Geertrui; Smet, Annemieke; Dewulf, Jeroen; Heyndrickx, Marc; Imberechts, Hein; Haesebrouck, Freddy; Butaye, Patrick; Croubels, Siska

2016-09-20

Cross-contamination of feed with low concentrations of antimicrobials can occur at production, transport and/or farm level. Concerns are rising about possible effects of this contaminated feed on resistance selection in the intestinal microbiota. Therefore, an experiment with pigs was set up, in which intestinal and fecal concentrations of chlortetracycline (CTC), doxycycline (DOX) and sulfadiazine-trimethoprim (SDZ-TRIM) were determined after administration of feed containing a 3 % carry-over level of these antimicrobials. The poor oral bioavailability of tetracyclines resulted in rather high concentrations in cecal and colonic content and feces at steady-state conditions. A mean concentration of 10 mg/kg CTC and 4 mg/kg DOX in the feces was reached, which is higher than concentrations that were shown to cause resistance selection. On the other hand, lower mean levels of SDZ (0.7 mg/kg) and TRIM (< limit of detection of 0.016 mg/kg) were found in the feces, corresponding with the high oral bioavailability of SDZ and TRIM in pigs. The relation between the oral bioavailability and intestinal concentrations of the tested antimicrobials, may be of help in assessing the risks of cross-contaminated feed. However, future research is needed to confirm our results and to evaluate the effects of these detected concentrations on resistance selection in the intestinal microbiota of pigs.
Time to B. cereus about hot chocolate.

PubMed Central

Nelms, P K; Larson, O; Barnes-Josiah, D

1997-01-01

OBJECTIVE: To determine the cause of illnesses experienced by employees of a Minneapolis manufacturing plant after drinking hot chocolate bought from a vending machine and to explore the prevalence of similar vending machine-related illnesses. METHODS: The authors inspected the vending machines at the manufacturing plant where employees reported illnesses and at other locations in the city where hot chocolate beverages were sold in machines. Tests were performed on dry mix, water, and beverage samples and on machine parts. RESULTS: Laboratory analyses confirmed the presence of B. cereus in dispensed beverages at a concentration capable of causing illness (170,000 count/gm). In citywide testing of vending machines dispensing hot chocolate, 7 of the 39 licensed machines were found to be contaminated, with two contaminated machines having B. cereus levels capable of causing illness. CONCLUSIONS: Hot chocolate sold in vending machines may contain organisms capable of producing toxins that under favorable conditions, can induce illness. Such illnesses are likely to be underreported. Even low concentrations of B. cereus may be dangerous for vulnerable populations such as the aged or immunosuppressed. Periodic testing of vending machines is thus warranted. The relationship between cleaning practices and B. cereus contamination is an issue for further study. PMID:9160059
Time to B. cereus about hot chocolate.

PubMed

Nelms, P K; Larson, O; Barnes-Josiah, D

1997-01-01

To determine the cause of illnesses experienced by employees of a Minneapolis manufacturing plant after drinking hot chocolate bought from a vending machine and to explore the prevalence of similar vending machine-related illnesses. The authors inspected the vending machines at the manufacturing plant where employees reported illnesses and at other locations in the city where hot chocolate beverages were sold in machines. Tests were performed on dry mix, water, and beverage samples and on machine parts. Laboratory analyses confirmed the presence of B. cereus in dispensed beverages at a concentration capable of causing illness (170,000 count/gm). In citywide testing of vending machines dispensing hot chocolate, 7 of the 39 licensed machines were found to be contaminated, with two contaminated machines having B. cereus levels capable of causing illness. Hot chocolate sold in vending machines may contain organisms capable of producing toxins that under favorable conditions, can induce illness. Such illnesses are likely to be underreported. Even low concentrations of B. cereus may be dangerous for vulnerable populations such as the aged or immunosuppressed. Periodic testing of vending machines is thus warranted. The relationship between cleaning practices and B. cereus contamination is an issue for further study.
Scrubbing of contaminants from contaminated air streams with aerogel materials with optional photocatalytic destruction

DOEpatents

Attia, Yosry A.

2000-01-01

Disclosed is a method for separating a vaporous or gaseous contaminant from an air stream contaminated therewith. This method includes the steps of: (a) passing said contaminated air into a contact zone in which is disposed an aerogel material capable of selecting adsorbing said contaminant from air and therein contacting said contaminated air with an aerogel material; and (b) withdrawing from said zone, air depleted of said contaminant. For present purposes, "contaminant" means a material not naturally occurring in ambient air and/or a material naturally occurring in air but present at a concentration above that found in ambient air. Thus, the present invention scrubs (or treats) air for the purpose of returning it to its ambient composition. Also disclosed herein is a process for the photocatalytic destruction of contaminants from an air stream wherein the contaminated air stream is passed into a control cell or contact zone in which is disposed a photocatalytic aerogel and exposing said aerogel to ultraviolet (UV) radiation for photocatalytically destroying the adsorbed contaminant, and withdrawing from said cell an exhaust air stream depleted in said contaminant.
The EmulSiv filter removes microbial contamination from propofol but is not a substitute for aseptic technique.

PubMed

Hall, Wendy C E; Jolly, Donald T; Hrazdil, Jiri; Galbraith, John C; Greacen, Maria; Clanachan, Alexander S

2003-01-01

To evaluate the ability of the EmulSiv filter (EF) to remove extrinsic microbial contaminants from propofol. Aliquots of Staphylococcus aureus (S. aureus), Candida albicans (C. albicans), Klebsiella pneumoniae (K. pneumoniae), Moraxella osloensis (M. osloensis), Enterobacter agglomerans (E. agglomerans), Escherichia coli (E. coli), Serratia marcescens (S. marcescens), Moraxella catarrhalis (M. catarrhalis), Haemophilus influenzae (H. influenzae) and Campylobacter jejuni (C. jejuni) were inoculated into vials containing 20 mL of sterile propofol. The unfiltered inoculated propofol solutions served as controls. Ten millilitres and 20 mL samples of the inoculated propofol were filtered through the EF. All solutions were then subplated onto three culture plates using a precision 1 micro L calibrated platinum loop and incubated. The number of colony forming units (CFU) were counted. Data were analyzed using a one-sample t test, and a P value of less than 0.05 was selected as the level of statistical significance. The EF was able to completely remove CFU of S. aureus, C. albicans, K. pneumoniae, M. osloensis, E. agglomerans, E. coli, S. marcescens, and M. catarrhalis (P < 0.05). A small number of H. influenzae CFU were able to evade filtration in both the 10 mL and 20 mL samples. C. jejuni CFU were able to evade filtration in only the 10 mL sample. The EF removes the majority of microbial contaminates from propofol with the exception of H. influenzae and C. jejuni. Although the EF is capable of removing most of the microbial contamination produced by H. influenzae and C. jejuni, a few CFU are capable of evading filtration. Consequently, even the use of a filter capable of removing microbial contaminants is not a substitute for meticulous aseptic technique and prompt administration when propofol is used.
Electrokinetic removal of charged contaminant species from soil and other media using moderately conductive adsorptive materials

DOEpatents

Lindgren, Eric R.; Mattson, Earl D.

2001-01-01

Method for collecting and concentrating charged species, specifically, contaminant species in a medium, preferably soil. The method utilizes electrokinesis to drive contaminant species into and through a bed adjacent to a drive electrode. The bed comprises a moderately electrically conductive adsorbent material which is porous and is infused with water or other solvent capable of conducting electrical current. The bed material, preferably activated carbon, is easily removed and disposed of. Preferably, where activated carbon is used, after contaminant species are collected and concentrated, the mixture of activated carbon and contaminant species is removed and burned to form a stable and easily disposable waste product.
A Space Experiment to Measure the Atomic Oxygen Erosion of Polymers and Demonstrate a Technique to Identify Sources of Silicone Contamination

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; deGroh, Kim K.; Baney-Barton, Elyse; Sechkar, Edward A.; Hunt, Patricia K.; Willoughby, Alan; Bemer, Meagan; Hope, Stephanie; Koo, Julie; Kaminski, Carolyn;

1999-01-01

A low Earth orbital space experiment entitled, "Polymers Erosion And Contamination Experiment", (PEACE) has been designed as a Get-Away Special (GAS Can) experiment to be accommodated as a Shuttle in-bay environmental exposure experiment. The first objective is to measure the atomic oxygen erosion yields of approximately 40 different polymeric materials by mass loss and erosion measurements using atomic force microscopy. The second objective is to evaluate the capability of identifying sources of silicone contamination through the use of a pin-hole contamination camera which utilizes environmental atomic oxygen to produce a contaminant source image on an optical substrate.

System and method for the identification of radiation in contaminated rooms

DOEpatents

Coleman, Jody Rustyn; Farfan, Eduardo B.

2015-09-29

Devices and methods for the characterization of areas of radiation in contaminated rooms are provided. One such device is a collimator with a collimator shield for reducing noise when measuring radiation. A position determination system is provided that may be used for obtaining position and orientation information of the detector in the contaminated room. A radiation analysis method is included that is capable of determining the amount of radiation intensity present at known locations within the contaminated room. Also, a visual illustration system is provided that may project images onto the physical objects, which may be walls, of the contaminated room in order to identify the location of radioactive materials for decontamination.
Draft Genome Sequence of Brevibacterium linens AE038-8, an Extremely Arsenic-Resistant Bacterium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maizel, Daniela; Utturkar, Sagar M.; Brown, Steven D.

To understand the arsenic biogeocycles in the groundwaters at Tucumán, Argentina, we isolated Brevibacterium linens sp. strain AE38-8, obtained from arsenic-contaminated well water. This strain is extremely resistant to arsenicals and has arsenic resistance (ars) genes in its genome. Here, we report the draft genome sequence of B. linens AE38-8.
Draft Genome Sequence of Brevibacterium linens AE038-8, an Extremely Arsenic-Resistant Bacterium

DOE PAGES

Maizel, Daniela; Utturkar, Sagar M.; Brown, Steven D.; ...

2015-04-16

To understand the arsenic biogeocycles in the groundwaters at Tucumán, Argentina, we isolated Brevibacterium linens sp. strain AE38-8, obtained from arsenic-contaminated well water. This strain is extremely resistant to arsenicals and has arsenic resistance (ars) genes in its genome. Here, we report the draft genome sequence of B. linens AE38-8.
JPL Contamination Control Engineering

NASA Technical Reports Server (NTRS)

Blakkolb, Brian

2013-01-01

JPL has extensive expertise fielding contamination sensitive missions-in house and with our NASA/industry/academic partners.t Development and implementation of performance-driven cleanliness requirements for a wide range missions and payloads - UV-Vis-IR: GALEX, Dawn, Juno, WFPC-II, AIRS, TES, et al - Propulsion, thermal control, robotic sample acquisition systems. Contamination control engineering across the mission life cycle: - System and payload requirements derivation, analysis, and contamination control implementation plans - Hardware Design, Risk trades, Requirements V-V - Assembly, Integration & Test planning and implementation - Launch site operations and launch vehicle/payload integration - Flight ops center dot Personnel on staff have expertise with space materials development and flight experiments. JPL has capabilities and expertise to successfully address contamination issues presented by space and habitable environments. JPL has extensive experience fielding and managing contamination sensitive missions. Excellent working relationship with the aerospace contamination control engineering community/.
A Meta-Analysis of the Global Prevalence Rates of Staphylococcus aureus and Methicillin-Resistant S. aureus Contamination of Different Raw Meat Products.

PubMed

Ou, Qianting; Peng, Yang; Lin, Dongxin; Bai, Chan; Zhang, Ting; Lin, Jialing; Ye, Xiaohua; Yao, Zhenjiang

2017-03-30

Previous research has indicated that raw meats are frequently contaminated with Staphylococcus aureus , but data regarding the pooled prevalence rates of S. aureus and methicillin-resistant S. aureus (MRSA) contamination in different types of raw meat products (beef, chicken, and pork) and across different periods, regions, and purchase locations remain inconsistent. We systematically searched the PubMed, EMBASE, Ovid, Web of Science, and HighWire databases to identify studies published up to June 2016. The STROBE guidelines were used to assess the quality of the 39 studies included in this meta-analysis. We observed no significant differences in the pooled prevalence rates of S. aureus and MRSA contamination identified in various raw meat products, with overall pooled prevalence rates of 29.2% (95% confidence interval [CI], 22.8 to 35.9%) and 3.2% (95% CI, 1.8 to 4.9%) identified for the two contaminants, respectively. In the subgroup analyses, the prevalence of S. aureus contamination in chicken products was highest in Asian studies and significantly decreased over time worldwide. In European studies, the prevalence rates of S. aureus contamination in chicken and pork products were lower than those reported on other continents. The pooled prevalence rates of S. aureus contamination in chicken and pork products and MRSA contamination in beef and pork products were significantly higher in samples collected from retail sources than in samples collected from slaughterhouses and processing plants. These results highlight the need for good hygiene during transportation to and manipulation at retail outlets to reduce the risk of transmission of S. aureus and MRSA from meat products to humans.
Salmonella spp. and Extended-Spectrum Cephalosporin-Resistant Escherichia coli Frequently Contaminate Broiler Chicken Transport Cages of an Organic Production Company.

PubMed

Mollenkopf, Dixie F; De Wolf, Brittany; Feicht, Sydnee M; Cenera, Johana K; King, Christy A; van Balen, Joany C; Wittum, Thomas E

2018-06-06

Antimicrobial resistant bacteria in retail meat pose a health hazard to the public, as does contamination of these products with Salmonella. Our aim was to determine the prevalence of Salmonella as well as Escherichia coli expressing AmpC and extended-spectrum beta-lactamase (ESBL) resistance phenotypes contaminating broiler transport cages and fresh, retail ground chicken meat. Sterile gauze sponges were used to collect duplicate cage floor samples from transport trailers that deliver market-ready birds to a single organic poultry-processing facility. With the exception of the first visit (n = 25), 50 duplicate cage floor samples were collected using moistened sterile gauze sponges on each of nine weekly visits during May, June, and July 2013. Additionally, fresh, retail ground chicken meat was sampled at each weekly visit from an on-site retail store located at the same processing facility. A total of 425 cage swabs and 72 ground chicken aliquots from 24 retail packages were collected and screened for the presence of Salmonella as well as E. coli expressing resistance to extended-spectrum cephalosporins using selective culture. We recovered Salmonella from 26.1% of cage swab samples and 2.8% of retail meat samples. E. coli expressing AmpC and ESBL resistance phenotypes were recovered from 84.9% and 22.6% of cage swabs and 77.8% and 11.1% of fresh, retail ground meat samples, respectively. Our results suggest that transport cages could potentially act as a source of broiler exposure to both Salmonella and enteric bacteria resistant to important antimicrobial drugs as they are transported for entry into the food supply as fresh, retail meat products.
Bioremediation of mercury: not properly exploited in contaminated soils!

PubMed

Mahbub, Khandaker Rayhan; Bahar, Md Mezbaul; Labbate, Maurizio; Krishnan, Kannan; Andrews, Stuart; Naidu, Ravi; Megharaj, Mallavarapu

2017-02-01

Contamination of land and water caused by heavy metal mercury (Hg) poses a serious threat to biota worldwide. The seriousness of toxicity of this neurotoxin is characterized by its ability to augment in food chains and bind to thiol groups in living tissue. Therefore, different remediation approaches have been implemented to rehabilitate Hg-contaminated sites. Bioremediation is considered as cheaper and greener technology than the conventional physico-chemical means. Large-scale use of Hg-volatilizing bacteria are used to clean up Hg-contaminated waters, but there is no such approach to remediate Hg-contaminated soils. This review focuses on recent uses of Hg-resistant bacteria in bioremediation of mercury-contaminated sites, limitation and advantages of this approach, and identifies the gaps in existing research.
COUPLED FREE AND DISSOLVED PHASE TRANSPORT: NEW SIMULATION CAPABILITIES AND PARAMETER INVERSION

EPA Science Inventory

The vadose zone free-phase simulation capabilities of the US EPA Hydrocarbon Spill Screening Model (HSSM) (Weaver et al., 1994) have been linked with the 3-D multi-species dissolved-phase contaminant transport simulator MT3DMS (Zheng and Wang, 1999; Zheng, 2005). The linkage pro...
Bioremediation of heavy metal-contaminated effluent using optimized activated sludge bacteria

NASA Astrophysics Data System (ADS)

Bestawy, Ebtesam El.; Helmy, Shacker; Hussien, Hany; Fahmy, Mohamed; Amer, Ranya

2013-03-01

Removal of heavy metals from contaminated domestic-industrial effluent using eight resistant indigenous bacteria isolated from acclimatized activated sludge was investigated. Molecular identification using 16S rDNA amplification revealed that all strains were Gram-negative among which two were resistant to each of copper, cadmium and cobalt while one was resistant to each of chromium and the heavy metal mixture. They were identified as Enterobacter sp. (Cu1), Enterobacter sp. (Cu2), Stenotrophomonas sp. (Cd1), Providencia sp. (Cd2), Chryseobacterium sp. (Co1), Comamonas sp. (Co2), Ochrobactrum sp. (Cr) and Delftia sp. (M1) according to their resistance pattern. Strains Cu1, Cd1, Co2 and Cr were able to resist 275 mg Cu/l, 320 mg Cd/l, 140 mg Co/l and 29 mg Cr/l respectively. The four resistant strains were used as a mixture to remove heavy metals (elevated concentrations) and reduce the organic load of wastewater effluent. Results revealed that using the proposed activated sludge with the resistant bacterial mixture was more efficient for heavy metal removal compared to the activated sludge alone. It is therefore recommended that the proposed activated sludge system augmented with the acclimatized strains is the best choice to ensure high treatment efficiency and performance under metal stresses especially when industrial effluents are involved.

Monitoring the degradation capability of novel haloalkaliphilic tributyltin chloride (TBTCl) resistant bacteria from butyltin-polluted site.

PubMed

Hassan, Hamdy A; Dawah, Somya E; El-Sheekh, Mostafa M

2018-03-28

Tributyltin (TBT) is recognized as a major environmental problem at a global scale. Haloalkaliphilic tributyltin (TBT)-degrading bacteria may be a key factor in the remediation of TBT polluted sites. In this work, three haloalkaliphilic bacteria strains were isolated from a TBT-contaminated site in the Mediterranean Sea. After analysis of the 16S rRNA gene sequences the isolates were identified as Sphingobium sp. HS1, Stenotrophomonas chelatiphaga HS2 and Rhizobium borbori HS5. The optimal growth conditions for biodegradation of TBT by the three strains were pH 9 and 7% (w/v) salt concentration. S. chelatiphaga HS2 was the most effective TBT degrader and has the ability to transform most TBT into dibutyltin and monobutyltin (DBT and MBT). A gene was amplified from strain HS2 and identified as TBTB-permease-like, that encodes an ArsB-permease. A reverse transcription polymerase chain reaction analysis in the HS2 strain confirmed that the TBTB-permease-like gene contributes to TBT resistance. The three novel haloalkaliphilic TBT degraders have never been reported previously. Copyright © 2018 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.
A Study of Emergency Room Health CAre Providers and the Fixed Facility Physical Capabilities to Manage the Presenting Radiologically Injured Patient

DTIC Science & Technology

1984-08-01

large areas 6. Contaminated hair 35 a. Shampoo with mild soap for three minutes and rinse b. Monitor and repeat step a as needed c. If contamination...M counters are generally used for surveying low-level radiation and are calibrated either in counts per minute (CPM) or milloroentgens per hours (mR... surveyed for contamination? Decontaminated D. Nature of accident: Type radiation source Other Details: E. Person in charge of radiation evaluation: F
Simulated discharge of treated landfill leachates reveals a fueled development of antibiotic resistance in receiving tidal river.

PubMed

Wu, Dong; Ma, Ruoqi; Wei, Huawei; Yang, Kai; Xie, Bing

2018-05-01

Around 350 million tons of solid waste is disposed of in landfills every year globally, with millions of cubic meters of landfill leachates released into neighboring environment. However, to date, little is known about the variations of antimicrobial resistance (AMR) in on-site leachate treatment systems and its development in leachate-receiving water environment. Here, we quantified 7 subtypes of antibiotic resistance genes (ARGs), 3 types of culturable antibiotic resistant bacteria (ARB) and 6 subtypes of mobile genetic elements (MGEs) in the effluents from a combined leachate treatment process, including biological treatment (MBR), physical separation (UF), ultraviolet (UV) disinfection and advanced oxidation process (AOP). The contents of ARGs, ARB and MGEs were generally enriched by the MBR, but then decreased significantly along with the tertiary treatment process. However, in the effluent-receiving water samples, the abundance of dominant ARGs (i.e. ermB, sul1, bla TEM ) increased by 1.5 orders of magnitude within 96 h, alongside a general increase of MGEs (~10.0 log 10 (copies/mL) and total ARB (~1100 CFU/mL). Structural correlation analyses reveal that target ARGs were closely associated with MGEs, particularly in effluent-receiving samples (Procrustes test; M 2  = 0.49, R = 0.71, P = 0.001); and occurrences of ARB were majorly affected by ARG's distribution and environmental conditions (e.g. nitrogen speciation) in effluent and recipient groups, respectively. This study indicates that current treatment technologies and operation protocols are not feasible in countering the development of AMR in effluent-receiving water environment, particularly in tidal rivers that are capable of retaining contaminants for a long residence time. Copyright © 2018 Elsevier Ltd. All rights reserved.
Prospects for using existing resists for evaluating 157-nm imaging systems

NASA Astrophysics Data System (ADS)

Fedynyshyn, Theodore H.; Kunz, Roderick R.; Doran, Scott P.; Goodman, Russell B.; Lind, Michele L.; Curtin, Jane E.

2000-06-01

Lithography at 157 nm represents the next evolutionary step in the Great Optical Continuum and is currently under investigation as a possible successor to 193-nm lithography. If successful, the photoresists used for this technology must be initially capable of 100-nm resolution and be extendable to less than 70 nm. Unfortunately, as with the transition to shorter wavelengths in the past, the photoresist materials developed for longer wavelengths appear to be too absorbent for practical use as a traditional high resolution single layer resist imageable with 157 nm radiation. Until new photoresist materials are developed that are sufficiently transparent to be used as single layer resists, the existing need for a resist to be used to evaluate 157 nm imaging systems, such as the prototype steppers now under development, will have to be met by employing existing resists. We have surveyed the commercial resist market with the dual purpose of identifying the general categories of commercial resists that have potential for use as tool evaluation resist and to baseline these resists for comparison against future 157 nm resist candidates. Little difference was observed in the 157- nm absorbance between different classes of resists with most resists having an absorbance between 6 and 8 per micron. Due to the high absorbance at 157 nm of polyhydroxystyrene, polyacrylate, and polycyclic copolymer based resists, the coated resist thickness will need to be under 100 nm. All four commercial resists evaluated for imaging at 157 nm showed that they are capable of acting as a tool testing resist to identify issues attributed focus, illumination, and vibration. Finally, an improved tool testing resist can be developed within the existing resist material base, that is capable of 100 nm imaging with a binary mask and 70 nm imaging with a phase shift mask. Minor formulation modification can greatly improve resist performance including improved resolution and reduced line edge roughness.
Contaminant and other elements in soil (CCQM-K127)

NASA Astrophysics Data System (ADS)

Rocio Arvizu Torres, M.; Manzano, J. Velina Lara; Valle Moya, Edith; Horvat, Milena; Jaćimović, Radojko; Zuliani, Tea; Vreča, Polona; Acosta, Osvaldo; Bennet, John; Snell, James; Almeida, Marcelo D.; de Sena, Rodrigo C.; Dutra, Emily S.; Yang, Lu; Li, Haifeng

2017-01-01

Non-contaminated soils contain trace and major elements at levels representing geochemical background of the region. The main sources of elements as contaminants/pollutants in soils are mining and smelting activities, fossil fuel combustion, agricultural practices, industrial activities and waste disposal. Contaminated/polluted sites are of great concern and represent serious environmental, health and economic problems. Characterization and identification of contaminated land is the first step in risk assessment and remediation activities. It is well known that soil is a complex matrix with huge variation locally and worldwide. According to the IAWG's five year plan, it is recommended to have a key comparison under the measurement service category of soils and sediments for the year 2015. Currently 13 NMI has claimed calibration and measurement capabilities (CMCs) in category 13 (sediments, soils, ores, and particulates): 29 CMCs in soil and 96 CMCs in sediments. In this regard this is a follow-up comparison in the category 13; wherein three key comparisons have been carried out during the years 2000 (CCQM-K13), 2003 (CCQM-K28) and 2004 (CCQM-K44). Since it is important to update the capabilities of NMIs in this category. CENAM and JSI proposed a key comparison in this category and a pilot study in parallel. The proposed study was agreed by IAWG members, where two soils samples were used in both CCQM-K127 representing a non-contaminated soil with low contents of elements (arsenic, cadmium, iron, lead and manganese), and a contaminated soil with much higher content of selected elements (arsenic, cadmium, iron and lead). This broadens the scope and a degree of complexity of earlier measurements in this field. National metrology institutes (NMIs)/designate institutes (DIs) should, therefore, demonstrate their measurement capabilities of trace and major elements in a wide concentration ranges, representing background/reference sites as well as highly contaminated soils by their available analytical methods. This facilitated the investigation into the core capabilities of participants to measure the mass fraction of tested elements in soil and therefore to claim their CMCs as listed in appendix C of the key comparison database (KCDB) under the mutual recognition arrangement of the International Committee for Weights and Measures (CIPM MRA). In total 19 institutes (NMIs/Dis) participated in the key comparison and the reported results of the key comparison were from 18 institutes (NMIs/DIs); 151 measurements were reported for CCQM-K127. The analytical techniques selected by the participant institutes were ICP-MS, ICP-OES, FAAS, ET-AAS and INAA (k0-method of INAA); the sample preparation methods used were based on microwave assisted digestion, except when it was used INAA. After discussions it agreed to use the median as KCRV and the MMADe as u(xKCRV). Generally most of the results of the participants were found to be consistent for all measurements according to their equivalence statements, with the exception of some extreme values, which were identified with a value of di/U(di) higher than 1. This key comparison is a means of providing evidence for practical demonstration of a CCQM comparison calibration and measurement capabilities (CMCs) claims for contaminant and others elements, in low and medium content levels in non-contaminated and contaminated matrices described in category 13. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Phytoplankton communities of polar regions--Diversity depending on environmental conditions and chemical anthropopressure.

PubMed

Kosek, Klaudia; Polkowska, Żaneta; Żyszka, Beata; Lipok, Jacek

2016-04-15

The polar regions (Arctic and Antarctic) constitute up to 14% of the biosphere and offer some of the coldest and most arid Earth's environments. Nevertheless several oxygenic phototrophs including some higher plants, mosses, lichens, various algal groups and cyanobacteria, survive that harsh climate and create the base of the trophic relationships in fragile ecosystems of polar environments. Ecosystems in polar regions are characterized by low primary productivity and slow growth rates, therefore they are more vulnerable to disturbance, than those in temperate regions. From this reason, chemical contaminants influencing the growth of photoautotrophic producers might induce serious disorders in the integrity of polar ecosystems. However, for a long time these areas were believed to be free of chemical contamination, and relatively protected from widespread anthropogenic pressure, due their remoteness and extreme climate conditions. Nowadays, there is a growing amount of data that prove that xenobiotics are transported thousands of kilometers by the air and ocean currents and then they are deposed in colder regions and accumulate in many environments, including the habitats of marine and freshwater cyanobacteria. Cyanobacteria (blue green algae), as a natural part of phytoplankton assemblages, are globally distributed, but in high polar ecosystems they represent the dominant primary producers. These microorganisms are continuously exposed to various concentration levels of the compounds that are present in their habitats and act as nourishment or the factors influencing the growth and development of cyanobacteria in other way. The most common group of contaminants in Arctic and Antarctic are persistent organic pollutants (POPs), characterized by durability and resistance to degradation. It is important to determine their concentrations in all phytoplankton species cells and in their environment to get to know the possibility of contaminants to transfer to higher trophic levels, considering however that some strains of microalgae are capable of metabolizing xenobiotics, make them less toxic or even remove them from the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.
Drugs in Your Drinking Water: Removing Pharmaceutical Pollution

NASA Astrophysics Data System (ADS)

Richardson, K.

2017-12-01

Pharmaceuticals, mostly estrogen-based hormones and antibiotics, are increasingly polluting waterways and contaminating municipal drinking water sources. A 2008 study funded by the American Water Works Association Research Foundation and the WateReuse Foundation tested 19 drinking water treatment plants across the United States. The study found pharmaceuticals and metabolites at all of the locations tested. These plants provide drinking water for over 28 million Americans - yet only five states test for pharmaceuticals. A 2007 US Government Accountability Office study of male smallmouth bass showed ovarian tissue in their gonads and concluded the combination of EDCs (Endocrine Disrupting Chemicals) likely caused the feminization of the male fish. The purpose of this project is to determine whether bivalves can effectively remove pharmaceuticals as well as other CECs (Contaminants of Emerging Concern).Pharmaceuticals, specifically ibuprofen, were found to be resistant to chemical and mechanical filtration methods, such as coffee grounds and activated carbon, so biological filtration methods are used. Three types of common mollusks (Sphaeriidae `fingernail clams', freshwater mussels, scallops) will be used to assess the potential for biological remediation of the chemical pollutants. Fifteen specimens of each species will be used - a total of 45 individuals. Each group of five will be introduced to either an NSAID (ibuprofen), oil (vegetable) or hormone (estrogen, pending approval). This creates an array of 3 species and 3 contaminants, for a 3x3 grid of nine sample groups. Water is contaminated with pollutant levels similar to EPA measurements. The concentration will be measured before and after the introduction of the specimens using a UV spectrophotometer, at regular time intervals. As mollusks are capable of filtering up to two liters of water a day, the 37.8 liter tanks are filtered at a rate of 10 liters a day. A successful trial of bivalves reducing and filtering out CECs could potentially be used to remove harmful substances from drinking water and our oceans, sustaining our earth and preserving it for generations to come.
Long Term Geoelectrical Monitoring of Deep-water Horizon Oil Spill in the Gulf Coast

NASA Astrophysics Data System (ADS)

Heenan, J. W.; Ntarlagiannis, D.; Slater, L. D.; Atekwana, E. A.; Ross, C.; Nolan, J. T.; Atekwana, E. A.

2011-12-01

In the aftermath of the catastrophic Deep-water Horizon (DWH) spill in the Gulf Coast, opportunities exist to study the evolution of fresh crude oil contamination in beach sediments and marshes. Grand Terre 1 Island, off the coast of Grand Isle in southern Louisiana, is an uninhabited barrier island, heavily impacted by the DWH spill, and ideal for undisturbed long term monitoring of crude oil degradation processes. A 10 channel Syscal-Pro resistivity / IP instrument (IRIS Instruments, France) is the heart of the fully autonomous geoelectrical monitoring system; the system, which is housed in a weatherproof container, relies solely on solar power, is controlled by an energy efficient PC and can be accessed remotely via web tools. The monitoring scheme involves collecting bi-daily resistivity measurements from surface and shallow boreholes, ranging from January 2011 to the present; environmental parameters, such as T, are continuously recorded at several depths. During regular field trips we perform larger scale geophysical surveys, and geochemical measurements (pH, DO, T, fluid C) to support the continuous geophysical monitoring. The contaminated layer on site is a visually distinctive layer of crude oil, isolated by cleaner sands above and below which is identified by a clear and obvious resistive anomaly in preliminary surveys. Early results show a decrease in average of the resistance values of each dataset over time. Further processing of the data yields a linearly shaped resistive anomaly, which coincides with the location of the oil layer. The changes in subsurface resistivity appear to be focused within this anomaly. Time filtering of the data by the time that they were collected, morning or evening, reveals a diurnal variation. While both time frames follow the same overall trend, the measurements in the morning are slightly more resistive than those in the evening. This indicates that there are environmental factors, such as temperature, that need to be accounted for when analyzing the data for evidence of biological processes. These preliminary findings indicate changes in the subsurface properties of the contaminated area and suggest that geoelectrical methods are sensitive to contamination evolution processes. Such geophysical data, constrained by geochemical and microbiological information, have the potential to be used as a long term monitoring tool for biological and geochemical processes in the subsurface.
Narrow grass hedges reduce tylosin and associated antimicrobial resistance genes in agricultural runoff

USDA-ARS?s Scientific Manuscript database

Agricultural runoff from areas receiving livestock manure can potentially contaminate surface water with antimicrobials and antimicrobial resistance genes (ARGs). The objective of this study was to investigate the effectiveness of narrow grass hedges (NGHs) on reducing the transport of antimicrobial...
Prevalence, Seasonal Occurrence, and Antimicrobial Resistance of Salmonella spp. Isolates Recovered from Chicken Carcasses Sampled at Major Poultry Processing Plants of South Korea.

PubMed

Lee, Soo-Kyoung; Choi, Dasom; Kim, Hong-Seok; Kim, Dong-Hyeon; Seo, Kun-Ho

2016-10-01

The current study was conducted to assess Salmonella spp. contamination in chicken carcasses produced at major poultry processing plants in South Korea. In total, 120 chicken carcasses were collected through 12 individual trials (10 chickens per trial) from six poultry processing plants in the summer of 2014 and the winter of 2015. Eighteen chicken samples (15%) were contaminated with Salmonella, with a higher rate of contamination observed during summer (14 isolates, 11.7%) than during winter (four isolates, 3.3%). Salmonella enterica serotype Typhimurium was the most prevalent, followed by Salmonella Hadar, Salmonella Rissen, Salmonella Bareilly, and Salmonella Virchow. Among five multidrug resistant isolates, a single strain was resistant to 10 antibiotics, including third-generation cephalosporins. This cephalosporin-resistant strain exhibited the extended-spectrum β-lactamase (ESBL) phenotype and harbored the gene encoding CTX-M-15, the most prevalent ESBL enzyme worldwide. Herein, repetitive-sequence-based polymerase chain reaction (rep-PCR) subtyping was conducted to discriminate the isolated Salmonella spp. and the ESBL-producing Salmonella isolate was distinguished by rep-PCR molecular subtyping, showing low genetic similarity in their rep-PCR-banding patterns. Given that poultry processing plants are the last stage in the chicken-production chain, the occurrence of Salmonella spp. including ESBL-producing strain in individually packaged chicken products highlights the necessity for regular monitoring for Salmonella in poultry processing plants.
International-Aerial Measuring System (I-AMS) Training Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wasiolek, Piotre T.; Malchor, Russell L.; Maurer, Richard J.

2015-10-01

Since the Fukushima reactor accident in 2011, there has been an increased interest worldwide in developing national capabilities to rapidly map and assess ground contamination resulting from nuclear reactor accidents. The capability to rapidly measure the size of the contaminated area, determine the activity level, and identify the radionuclides can aid emergency managers and decision makers in providing timely protective action recommendations to the public and first responders. The development of an aerial detection capability requires interagency coordination to assemble the radiation experts, detection system operators, and aviation aircrews to conduct the aerial measurements, analyze and interpret the data, andmore » provide technical assessments. The Office of International Emergency Management and Cooperation (IEMC) at the U.S. Department of Energy, National Nuclear Security Administration (DOE/NNSA) sponsors an International - Aerial Measuring System (I-AMS) training program for partner nations to develop and enhance their response to radiological emergencies. An initial series of courses can be conducted in the host country to assist in developing an aerial detection capability. As the capability develops and expands, additional experience can be gained through advanced courses with the opportunity to conduct aerial missions over a broad range of radiation environments.« less
A STUDY TO DETERMINE THE FEASIBILITY OF USING A GROUND-PENETRATING RADAR FOR MORE EFFECTIVE REMEDIATION OF SUBSURFACE CONTAMINATION

EPA Science Inventory

A study was conducted (1) to assess the capability of groundpenetrating radar (GPR) to identify natural subsurface features, detect man-made objects burled in the soil, and both detect and define the extent of contaminated soil or ground water due to a toxic spill, and (2) to det...
PRELIMINARY SURVEY OF CHEMICAL CONTAMINANTS IN WATER, SEDIMENT, AND AQUATIC BIOTA AT SELECTED SITES IN NORTHEASTERN FLORIDA BAY AND CANAL C-111

EPA Science Inventory

Several actions are under way to alter water management capabilities and practices in south Florida in order to restore a more natural hydroperiod for the Everglades. Because relatively little research has been conducted on contaminants entering Florida Bay, we undertook a prelim...
Method of purifying neutral organophosphorus extractants

DOEpatents

Horwitz, E. Philip; Gatrone, Ralph C.; Chiarizia, Renato

1988-01-01

A method for removing acidic contaminants from neutral mono and bifunctional organophosphorous extractants by contacting the extractant with a macroporous cation exchange resin in the H.sup.+ state followed by contact with a macroporous anion exchange resin in the OH.sup.- state, whereupon the resins take up the acidic contaminants from the extractant, purifying the extractant and improving its extraction capability.
40 CFR 141.23 - Inorganic chemical sampling and analytical requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Inorganic Contaminants Contaminant MCL (mg/l) Methodology Detection limit (mg/l) Antimony 0.006 Atomic... January 23, 2006. Unit then, the MCL is 0.05 mg/L. 7 The MDL reported for EPA method 200.9 (Atomic... higher. Using multiple depositions, EPA 200.9 is capable of obtaining MDL of 0.0001 mg/L. 8 Using...
Elevated [CO2] compromises both Type I and Type II wheat resistance to Fusarium head blight

USDA-ARS?s Scientific Manuscript database

Fusarium head blight (FHB) is one of the world’s most devastating wheat diseases, and results in significant yield loss and contamination of grain with harmful mycotoxins called trichothecenes. Despite emerging risks of increased mycotoxin contamination in food and feed associated with climate chang...
Occurrence and Antimicrobial Resistance of Listeria monocytogenes Recovered from Blue Crab Meat and Blue Crab Processing Plants

USDA-ARS?s Scientific Manuscript database

Listeria monocytogenes is widely distributed in the environment. The ubiquitous nature of this bacterium can result in contamination of foods. Listeriosis is a food-borne disease caused by consumption of L. monocytogenes-contaminated food. It is a public health problem of low incidence but high mort...
Breeding aflatoxin resistant maize lines using recent advances in technologies-a review

USDA-ARS?s Scientific Manuscript database

Aflatoxin contamination caused by Aspergillus flavus infection of corn is a significant and chronic threat to corn being used as food or feed. Contamination of crops at levels of 20 ppb or higher (as regulated by the FDA) by this toxin and potent carcinogen makes the crop unsalable. This review focu...
Radiation-resistant microorganism

DOEpatents

Fliermans, Carl B.

2007-01-09

An isolated and purified bacterium is provided which was isolated from a high-level radioactive waste site of mixed waste. The isolate has the ability to degrade a wide variety of organic contaminants while demonstrating high tolerance to ionizing radiation. The organism is uniquely suited to bioremediation of a variety or organic contaminants while in the presence of ionizing radiation.
Radiation-resistant microorganism

DOEpatents

Fliermans, Carl B.

2010-06-15

An isolated and purified bacterium is provided which was isolated from a high-level radioactive waste site of mixed waste. The isolate has the ability to degrade a wide variety of organic contaminants while demonstrating high tolerance to ionizing radiation. The organism is uniquely suited to bioremediation of a variety or organic contaminants while in the presence of ionizing radiation.

How Do I Sample the Environment and Equipment?

NASA Astrophysics Data System (ADS)

Kornacki, Jeffrey L.

Food product contamination from the post-processing environment is likely the most frequent cause of contaminated processed food product recalls and a significant source of poisoning outbreaks, and shelf life problems in North America with processed Ready-To-Eat foods. Conditions exist for the growth of microorganisms in most food processing factories. Failure to clean and effectively sanitize a microbial growth niche can lead to biofilm formation. Biofilms may be orders of magnitude more resistant to destruction by sanitizers. Cells in some biofilms have been shown to be 1,000 times more resistant to destruction than those which are freely suspended. This has implications for cleaning, sanitizing, sampling, and training. Sampling the factory environment is one means of monitoring the efficacy of microbiological control as well as a powerful tool for in-factory contamination investigation. Many sampling techniques exist and are discussed. It is important to recognize the difference between cleaning (removal of soil) and sanitization (reduction of microbial populations). Knowing where, when, and how to sample, how many samples to take, and what to test for and how to interpret test information is critical in finding and preventing contamination.
The Use of Electrical Resistivity Method to Mapping The Migration of Heavy Metals by Electrokinetic

NASA Astrophysics Data System (ADS)

Azhar, A. T. S.; Ayuni, S. A.; Ezree, A. M.; Nizam, Z. M.; Aziman, M.; Hazreek, Z. A. M.; Norshuhaila, M. S.; Zaidi, E.

2017-08-01

The presence of heavy metals contamination in soil environment highly needs innovative remediation. Basically, this contamination was resulted from ex-mining sites, motor workshop, petrol station, landfill and industrial sites. Therefore, soil treatment is very important due to metal ions are characterized as non-biodegradable material that may be harmful to ecological system, food chain, human health and groundwater sources. There are various techniques that have been proposed to eliminate the heavy metal contamination from the soil such as bioremediation, phytoremediation, electrokinetic remediation, solidification and stabilization. The selection of treatment needs to fulfill some criteria such as cost-effective, easy to apply, green approach and high remediation efficiency. Electrokinetic remediation technique (EKR) offers those solutions in certain area where other methods are impractical. While, electrical resistivity method offers an alternative geophysical technique for soil subsurface profiling to mapping the heavy metals migration by the influece of electrical gradient. Consequently, this paper presents an overview of the use of EKR to treat contaminated soil by using ERM method to verify their effectiveness to remove heavy metals.
Contamination of the Arctic reflected in microbial metagenomes from the Greenland ice sheet

NASA Astrophysics Data System (ADS)

Hauptmann, Aviaja L.; Sicheritz-Pontén, Thomas; Cameron, Karen A.; Bælum, Jacob; Plichta, Damian R.; Dalgaard, Marlene; Stibal, Marek

2017-07-01

Globally emitted contaminants accumulate in the Arctic and are stored in the frozen environments of the cryosphere. Climate change influences the release of these contaminants through elevated melt rates, resulting in increased contamination locally. Our understanding of how biological processes interact with contamination in the Arctic is limited. Through shotgun metagenomic data and binned genomes from metagenomes we show that microbial communities, sampled from multiple surface ice locations on the Greenland ice sheet, have the potential for resistance to and degradation of contaminants. The microbial potential to degrade anthropogenic contaminants, such as toxic and persistent polychlorinated biphenyls, was found to be spatially variable and not limited to regions close to human activities. Binned genomes showed close resemblance to microorganisms isolated from contaminated habitats. These results indicate that, from a microbiological perspective, the Greenland ice sheet cannot be seen as a pristine environment.
Leachate plume delineation and lithologic profiling using surface resistivity in an open municipal solid waste dumpsite, Sri Lanka.

PubMed

Wijesekara, Hasintha Rangana; De Silva, Sunethra Nalin; Wijesundara, Dharani Thanuja De Silva; Basnayake, Bendict Francis Antony; Vithanage, Meththika Suharshini

2015-01-01

This study presents the use of direct current resistivity techniques (DCRT) for investigation and characterization of leachate-contaminated subsurface environment of an open solid waste dumpsite at Kandy, Sri Lanka. The particular dumpsite has no liner and hence the leachate flows directly to the nearby river via subsurface and surface channels. For the identification of possible subsurface flow paths and the direction of the leachate, DCRT (two-dimensional, three-dimensional and vertical electrical sounding) have been applied. In addition, the physico-chemical parameters such as pH, electrical conductivity (EC), alkalinity, hardness, chloride, chemical oxygen demand (COD) and total organic carbon (TOC) of leachate collected from different points of the solid waste dumping area and leachate drainage channel were analysed. Resistivity data confirmed that the leachate flow is confined to the near surface and no separate plume is observed in the downstream area, which may be due to the contamination distribution in the shallow overburden thickness. The stratigraphy with leachate pockets and leachate plume movements was well demarcated inside the dumpsite via low resistivity zones (1-3 Ωm). The recorded EC, alkalinity, hardness and chloride contents in leachate were averaged as 14.13 mS cm⁻¹, 3236, 2241 and 320 mg L⁻¹, respectively, which confirmed the possible causes for low resistivity values. This study confirms that DCRT can be effectively utilized to assess the subsurface characteristics of the open dumpsites to decide on corridor placement and depth of permeable reactive barriers to reduce the groundwater contamination.
High Prevalence of Multidrug-Resistant Community-Acquired Methicillin-Resistant Staphylococcus aureus at the Largest Veterinary Teaching Hospital in Costa Rica

PubMed Central

Rojas, Irene; Barquero-Calvo, Elías; van Balen, Joany C.; Rojas, Norman; Muñoz-Vargas, Lohendy

2017-01-01

Abstract Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen associated with severe infections in companion animals present in the community, and it is diagnosed in animals admitted to veterinary hospitals. However, reports that describe the circulation of MRSA in animal populations and veterinary settings in Latin America are scarce. Therefore, the objective of this study was to determine the prevalence and investigate the molecular epidemiology of MRSA in the environment of the largest veterinary teaching hospital in Costa Rica. Preselected contact surfaces were sampled twice within a 6-week period. Antimicrobial resistance, SCCmec type, Panton-Valentine leukocidin screening, USA type, and clonality were assessed in all recovered isolates. Overall, MRSA was isolated from 26.5% (27/102) of the surfaces sampled, with doors, desks, and examination tables most frequently contaminated. Molecular analysis demonstrated a variety of surfaces from different sections of the hospital contaminated by three highly related clones/pulsotypes. All, but one of the isolates were characterized as multidrug-resistant SCCmec type IV-USA700, a strain sporadically described in other countries and often classified as community acquired. The detection and frequency of this unique strain in this veterinary setting suggest Costa Rica has a distinctive MRSA ecology when compared with other countries/regions. The high level of environmental contamination highlights the necessity to establish and enforce standard cleaning and disinfection protocols to minimize further spread of this pathogen and reduce the risk of nosocomial and/or occupational transmission of MRSA. PMID:28816638
Prevalence of Staphylococcus aureus and of methicillin-resistant S. aureus (MRSA) along the production chain of dairy products in north-western Greece.

PubMed

Papadopoulos, Panagiotis; Papadopoulos, Theofilos; Angelidis, Apostolos S; Boukouvala, Evridiki; Zdragas, Antonios; Papa, Anna; Hadjichristodoulou, Christos; Sergelidis, Daniel

2018-02-01

The objective of this study was to estimate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the production chain of dairy products. Of 367 tested samples (36 bulk tank milk (BTM), 19 dairy products, 72 human, 185 animal, 55 equipment), 212 (57.8%) were found positive for S. aureus. Almost all isolates (99.6%) were resistant to at least one antimicrobial and 13.3% were multi-drug resistant (MDR), exhibiting resistance to three or more antibiotic classes. Eleven samples (3%) were found contaminated by MRSA carrying the mecA gene. None of the MRSA isolates carried the mecC or the Pandon-Valentine leucocidin (PVL) genes. Four spa types were identified among the MRSA isolates: t127, t3586, t1773, t4038, with t127 being the most prevalent (7 out of 11). Two of them, t3586 and t1773, were isolated for the first time in Greece. Furthermore, Pulse-Field Gel Electrophoresis (PFGE) analysis indicated clonal circulation through the dairy production chain. The presence of MDR S. aureus, and especially MRSA, in animals and dairy products represents a potential threat for the spread of this pathogen in the community. The results indicated that human, animal and environmental sources could be involved in the contamination of dairy products along their production chain and therefore further investigation of contamination sources is needed to control the dispersion of MRSA in the community. Copyright © 2017 Elsevier Ltd. All rights reserved.
Contamination profiles of antibiotic resistance genes in the sediments at a catchment scale.

PubMed

Su, Hao-Chang; Pan, Chang-Gui; Ying, Guang-Guo; Zhao, Jian-Liang; Zhou, Li-Jun; Liu, You-Sheng; Tao, Ran; Zhang, Rui-Quan; He, Liang-Ying

2014-08-15

The aim of this study was to investigate the contamination profiles of tetracycline, sulfonamide, and macrolide resistance genes, as well as integrons in sediments of Dongjiang River basin of South China by real time quantitative polymerase chain reaction. sul2 was the most abundant resistance gene, with the average concentration of 6.97×10(8) copies/g and 1.00×10(8) copies/g in the dry and wet seasons, respectively, followed by ermF, sul3, sul1, intI1, tetA, ermB, tetX, tetM, tetQ, tetO, tetW, tetS, ermC, and tetB. The abundance of intI2 gene was the lowest in the sediment samples. Significant correlations existed between the ARGs and sediment properties as well as metals (Cu and Zn) and corresponding antibiotic classes, suggesting that the contamination of ARGs is related to chemical pollution of the sediments in the river basin. Principal component analysis showed distinct groupings of the sampling sites, reflecting that human activities are the key player in the dissemination of ARGs in the catchment environment. Copyright © 2014 Elsevier B.V. All rights reserved.
Comparison of remote consequences in Taraxacum officinale seed progeny collected in radioactively or chemically contaminated areas.

PubMed

Pozolotina, Vera N; Antonova, Elena V; Bezel, Victor S

2012-10-01

We carried out a comparative study of seed progeny taken from the dandelion (Taraxacum officinale s.l.) coenopopulations exposed for a long time to radioactive or chemical contamination originated from the East-Ural radioactive trace zone (EURT) or Nizhniy Tagil metallurgical combine impact zone (NTMC), respectively. Coenopopulations from EURT, NTMC and background areas significantly differ from each other with respect to the qualitative and quantitative composition of allozyme phenes. An analysis of clonal diversity showed the uniqueness of all coenopopulations in terms of their phenogenetics. P-generation seed viability was found to decrease in a similar manner as all types of the industrial stress increased. Studies of F (1)-generation variability in radio- and metal resistance by family analysis showed that seed progeny from EURT impact zone possessed high viability that, however, was accompanied by development of latent injuries resulting in low resistance to additional man-caused impacts. In F (1)-generation originated from NTMC zone, high seed viability was combined with increased resistance to provocative heavy metal and radiation exposure. No significant differences in responses to 'habitual' and 'new' factors, i.e. pre-adaptation effect, were found in samples from the contaminated areas.
The hyperaccumulator Sedum plumbizincicola harbors metal-resistant endophytic bacteria that improve its phytoextraction capacity in multi-metal contaminated soil.

PubMed

Ma, Ying; Oliveira, Rui S; Nai, Fengjiao; Rajkumar, Mani; Luo, Yongming; Rocha, Inês; Freitas, Helena

2015-06-01

Endophyte-assisted phytoremediation has recently been suggested as a successful approach for ecological restoration of metal contaminated soils, however little information is available on the influence of endophytic bacteria on the phytoextraction capacity of metal hyperaccumulating plants in multi-metal polluted soils. The aims of our study were to isolate and characterize metal-resistant and 1-aminocyclopropane-1-carboxylate (ACC) utilizing endophytic bacteria from tissues of the newly discovered Zn/Cd hyperaccumulator Sedum plumbizincicola and to examine if these endophytic bacterial strains could improve the efficiency of phytoextraction of multi-metal contaminated soils. Among a collection of 42 metal resistant bacterial strains isolated from the tissues of S. plumbizincicola grown on Pb/Zn mine tailings, five plant growth promoting endophytic bacterial strains (PGPE) were selected due to their ability to promote plant growth and to utilize ACC as the sole nitrogen source. The five isolates were identified as Bacillus pumilus E2S2, Bacillus sp. E1S2, Bacillus sp. E4S1, Achromobacter sp. E4L5 and Stenotrophomonas sp. E1L and subsequent testing revealed that they all exhibited traits associated with plant growth promotion, such as production of indole-3-acetic acid and siderophores and solubilization of phosphorus. These five strains showed high resistance to heavy metals (Cd, Zn and Pb) and various antibiotics. Further, inoculation of these ACC utilizing strains significantly increased the concentrations of water extractable Cd and Zn in soil. Moreover, a pot experiment was conducted to elucidate the effects of inoculating metal-resistant ACC utilizing strains on the growth of S. plumbizincicola and its uptake of Cd, Zn and Pb in multi-metal contaminated soils. Out of the five strains, B. pumilus E2S2 significantly increased root (146%) and shoot (17%) length, fresh (37%) and dry biomass (32%) of S. plumbizincicola as well as plant Cd uptake (43%), whereas Bacillus sp. E1S2 significantly enhanced the accumulation of Zn (18%) in plants compared with non-inoculated controls. The inoculated strains also showed high levels of colonization in rhizosphere and plant tissues. Results demonstrate the potential to improve phytoextraction of soils contaminated with multiple heavy metals by inoculating metal hyperaccumulating plants with their own selected functional endophytic bacterial strains. Copyright © 2015 Elsevier Ltd. All rights reserved.
Determination of geohydrologic framework and extent of d- water contamination using surface geophysical techniques at Picatinny Arsenal, New Jersey

USGS Publications Warehouse

Lacombe, Pierre

1986-01-01

Seismic-refraction, electric-resistivity sounding, and electromagnetic conductivity techniques were used to determine the geohydrologic framework and extent of groundwater contamination at Picatinny Arsenal in northern New Jersey. The area studied encompasses about 4 sq mi at the southern end of the Arsenal. The bedrock surface beneath the glacial sediments was delineated by seismic-refraction techniques. Data for 12 seismic lines were collected using a 12-channel engineering seismograph. Competent bedrock crops out on both sides of the valley, but is about 290 ft below land surface in the deepest part of the topographic valley. Where the exposed bedrock surface forms steep slopes on the valley side, it remains steep below the valley fill. Likewise, gentle bedrock valley slopes have gentle subsurface slopes. The deepest part of the bedrock valley is along the southern extension of the Green Pond fault. The electric-resistivity sounding technique was used to determine the sediment types. Data were collected from four sites using the offset Wenner electrode configuration. Below the surface layer, the sediments have apparent and computed resistivity values of 120 to 170 ohm-meters. These values correspond to a saturated fine-grained sediment such as silt or interbedded sand and clay. Groundwater contamination was by electromagnetic conductivity techniques using transmitting and receiving coils separated by 32.8 ft and 12 ft. Thirteen sites have apparent conductivity values exceeding 15 millimhos/m. Of these, seven sites indicate groundwater contamination from a variety of sources including a sanitary landfill, pyrotechnic testing ground, burning area, former domestic sewage field, salt storage facility, hazardous waste disposal lagoon, sewage treatment plant, and fertilizer storage shed. Three areas underlain by clay or muck are interpreted to be free of contamination. (Author 's abstract)
Organic contaminants in African aquatic systems: Current knowledge, health risks, and future research directions.

PubMed

Gwenzi, Willis; Chaukura, Nhamo

2018-04-01

Organic contaminants (OCs) are increasingly being reported in African aquatic systems, yet a critical evaluation of the literature is still lacking. The objectives of this review were to: (1) identify hotspot reservoirs, transfer pathways and ecological and human risks of OCs, (2) identify potential interventions to minimize the health risks, and (3) highlight knowledge gaps and research constraints. OCs widely reported in aquatic systems include pesticides, pharmaceuticals, plasticizers, solvents, endocrine disrupting compounds, and antimicrobial resistance genes, originating from applications in crop protection, veterinary and animal husbandry, human sanitation and hygiene, human vector and disease control. Potential hotspot reservoirs of OCs include wastewaters, on-site sanitation systems, leachates from non-engineered landfills and contaminated recharge of shallow groundwater systems. OCs could be transferred into humans via drinking of contaminated water, consumption of contaminated crops and aquatic foods, and to a lesser extent, inhalation and dermal contact. Ecological effects including intersex, estrogenicity, and acute and chronic toxicity occur in avian and aquatic species. Although the evidence base of human ecotoxicological effects of OC remains weak, pesticides have been reported in human milk, serum and sperms, pointing to potential chronic and acute toxicity and endocrine disruption. The prevalence of antimicrobials and their resistance genes could in turn lead to antimicrobial resistance in humans. The lack of OC monitoring in drinking water, coupled with over-reliance on untreated drinking water vulnerable to OC contamination predisposes humans to OC health risks. Appropriate water treatment methods, were identified, and a conceptual framework developed to minimize the ecological and human health risks. Future research directions on OC hotspot reservoirs, environmental behaviour and fate, ecotoxicology, epidemiology and interventions to minimize health risks are highlighted. However, lack of advanced analytical facilities in most African countries and other developing regions will continue to constrain OC research for now and in the foreseeable future. Copyright © 2017 Elsevier B.V. All rights reserved.
Humans or Animals? Global March of the Resistant Microbe

USDA-ARS?s Scientific Manuscript database

Antimicrobial resistance continues to be a global problem. Pathogens are global regardless of whether they are food borne or not. An example of an early century pathogen is Vibrio cholera and related species. Vibrio were primarily associated with water sources and foodstuffs contaminated with wat...
Selective spectrophotometric determination of TNT using a dicyclohexylamine-based colorimetric sensor.

PubMed

Erçağ, Erol; Uzer, Ayşem; Apak, Reşat

2009-05-15

Because of the extremely heterogeneous distribution of explosives in contaminated soils, on-site colorimetric methods are efficient tools to assess the nature and extent of contamination. To meet the need for rapid and low-cost chemical sensing of explosive traces or residues in soil and post-blast debris, a colorimetric absorption-based sensor for trinitrotoluene (TNT) determination has been developed. The charge-transfer (CT) reagent (dicyclohexylamine, DCHA) is entrapped in a polyvinylchloride (PVC) polymer matrix plasticised with dioctylphtalate (DOP), and moulded into a transparent sensor membrane sliced into test strips capable of sensing TNT showing an absorption maximum at 530 nm when placed in a 1-mm spectrophotometer cell. The sensor gave a linear absorption response to 5-50 mg L(-1) TNT solutions in 30% aqueous acetone with limit of detection (LOD): 3 mg L(-1). The sensor is only affected by tetryl, but not by RDX, pentaerythritoltetranitrate (PETN), dinitrotoluene (DNT), and picric acid. The proposed method was statistically validated for TNT assay against high performance liquid chromatography (HPLC) using a standard sample of Comp B. The developed sensor was relatively resistant to air and water, was of low-cost and high specificity, gave a rapid and reproducible response, and was suitable for field use of TNT determination in both dry and humid soil and groundwater with a portable colorimeter.
Use of thermophilic bacteria for bioremediation of petroleum contaminants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Maghrabi, I.M.A.; Bin Aqil, A.O.; Chaalal, O.

1999-01-01

Several strains of thermophilic bacteria were isolated from the environment of the United Arab Emirates. These bacteria show extraordinary resistance to heat and have their maximum growth rate around 60--80 C. This article investigates the potential of using these facultative bacteria for both in situ and ex situ bioremediation of petroleum contaminants. In a series of batch experiments, bacterial growth was observed using a computer image analyzer following a recently developed technique. These experiments showed clearly that the growth rate is enhanced in the presence of crude oil. This is coupled with a rapid degradation of the crude oil. Thesemore » bacteria were found to be ideal for breaking down long-chain organic molecules at a temperature of 40 C, which is the typical ambient temperature of the Persian Gulf region. The same strains of bacteria are also capable of surviving in the presence of the saline environment that can prevail in both sea water and reservoir connate water. This observation prompted further investigation into the applicability of the bacteria in microbial enhanced oil recovery. In the United Arab Emirates, the reservoirs are typically at a temperature of around 85 C. Finally, the performance of the bacteria is tested in a newly developed bioreactor that uses continuous aeration through a transverse slotted pipe. This reactor also uses mixing without damaging the filamentous bacteria. In this process, the mechanisms of bioremediation are identified.« less
Tackling antibiotic resistance: the environmental framework.

PubMed

Berendonk, Thomas U; Manaia, Célia M; Merlin, Christophe; Fatta-Kassinos, Despo; Cytryn, Eddie; Walsh, Fiona; Bürgmann, Helmut; Sørum, Henning; Norström, Madelaine; Pons, Marie-Noëlle; Kreuzinger, Norbert; Huovinen, Pentti; Stefani, Stefania; Schwartz, Thomas; Kisand, Veljo; Baquero, Fernando; Martinez, José Luis

2015-05-01

Antibiotic resistance is a threat to human and animal health worldwide, and key measures are required to reduce the risks posed by antibiotic resistance genes that occur in the environment. These measures include the identification of critical points of control, the development of reliable surveillance and risk assessment procedures, and the implementation of technological solutions that can prevent environmental contamination with antibiotic resistant bacteria and genes. In this Opinion article, we discuss the main knowledge gaps, the future research needs and the policy and management options that should be prioritized to tackle antibiotic resistance in the environment.
Bioremediation of contaminated groundwater

DOEpatents

Hazen, Terry C.; Fliermans, Carl B.

1995-01-01

An apparatus and method for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid is selected to stimulate the growth and reproduction of indigenous subsurface microorganisms that are capable of degrading the contaminants; an oxygenated fluid is selected to create a generally aerobic environment for these microorganisms to degrade the contaminants, leaving only pockets that are anaerobic. The nutrient fluid is injected periodically while the oxygenated fluid is injected continuously and both are extracted so that both are drawn across the plume. The nutrient fluid stimulates microbial colony growth; withholding it periodicially forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is reduced to an acceptable, preselected level. The nutrient fluid can be methane and the oxygenated fluid air for stimulating production of methanotrophs to break down chlorohydrocarbons, especially trichloroethylene (TCE) and tetrachloroethylene.
Bioremediation of contaminated groundwater

DOEpatents

Hazen, T.C.; Fliermans, C.B.

1995-01-24

An apparatus and method are described for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid is selected to stimulate the growth and reproduction of indigenous subsurface microorganisms that are capable of degrading the contaminants. An oxygenated fluid is selected to create a generally aerobic environment for these microorganisms to degrade the contaminants, leaving only pockets that are anaerobic. The nutrient fluid is injected periodically while the oxygenated fluid is injected continuously and both are extracted so that both are drawn across the plume. The nutrient fluid stimulates microbial colony growth. Withholding it periodically forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is reduced to an acceptable, preselected level. The nutrient fluid can be methane and the oxygenated fluid air for stimulating production of methanotrophs to break down chlorohydrocarbons, especially trichloroethylene (TCE) and tetrachloroethylene. 3 figures.
Presence and Antimicrobial Resistance of Escherichia coli in Ready-to-Eat Foods in Shaanxi, China.

PubMed

Baloch, Allah Bux; Yang, Hua; Feng, Yuqing; Xi, Meili; Wu, Qian; Yang, Qinhao; Tang, Jingsi; He, Xiangxiang; Xiao, Yingping; Xia, Xiaodong

2017-03-01

The aim of this study was to determine the presence and characteristics of Escherichia coli in ready-to-eat (RTE) foods. A total of 300 RTE foods samples were collected in Shaanxi Province, People's Republic of China: 50 samples of cooked meat, 165 samples of vegetable salad, 50 samples of cold noodles, and 35 samples of salted boiled peanuts. All samples were collected during summer (in July to October) 2011 and 2012 and surveyed for the presence of E. coli . E. coli isolates recovered were classified by phylogenetic typing using a PCR assay. The presence of Shiga toxin genes 1 (stx 1 ) and 2 (stx 2 ) was determined for these E. coli isolates by PCR, and all isolates were analyzed for antimicrobial susceptibility and the presence of class 1 integrons. Overall, 267 (89.0%) RTE food samples were positive for E. coli : 49 cold noodle, 46 cooked meat, 150 salad vegetable, and 22 salted boiled peanut samples. Of the 267 E. coli isolates, 73.0% belong to phylogenetic group A, 12.4% to group B1, 6.4% to group B2, and 8.2% to group D. All isolates were negative for both Shiga toxin genes. Among the isolates, 74.2% were resistant to at least one antimicrobial agent, and 17.6% were resistant to three or more antimicrobial agents. Resistance to ampicillin (75.6% of isolates) and tetracycline (73.1% of isolates) was most frequently detected; 26.2% of E. coli isolates and 68.8% of multidrug-resistant E. coli isolates were positive for class 1 integrons. All isolates were sensitive to amikacin. Our findings indicate that RTE foods in Shaanxi were commonly contaminated with antibiotic-resistant E. coli , which may pose a risk for consumer health and for transmission of antibiotic resistance. Future research is warranted to track the contamination sources and develop appropriate steps that should be taken by government, industry, and retailers to reduce microbial contamination in RTE foods.
Isolation of Multidrug-Resistant Escherichia coli O157 from Goats in the Somali Region of Ethiopia: A Cross-Sectional, Abattoir-Based Study.

PubMed

Dulo, Fitsum; Feleke, Aklilu; Szonyi, Barbara; Fries, Reinhard; Baumann, Maximilian P O; Grace, Delia

2015-01-01

Toxigenic Escherichia coli (E. coli) are an important cause of gastroenteritis in developing countries. In Ethiopia, gastroenteritis due to food-borne disease is a leading cause of death. Yet, there is no surveillance for E. coli O157 and little is known about the carriage of this pathogen in Ethiopia's livestock. This study aimed to assess the prevalence and levels of antimicrobial resistance of E. coli O157 in goat meat, feces, and environmental samples collected at a large abattoir in the Somali region of Ethiopia. The samples were enriched in modified tryptone broth containing novobiocin, and plated onto sorbitol MacConkey agar. Isolates were confirmed using indole test and latex agglutination. Antimicrobial susceptibility testing was conducted using the disk diffusion method. A total of 235 samples, including 93 goat carcass swabs, 93 cecal contents, 14 water, 20 hand, and 15 knife swabs were collected. Overall, six (2.5%) samples were contaminated with E. coli O157 of which two (2.1%) were isolated from cecal contents, three (3.2%) from carcass swabs, and one (7.1%) from water. All isolates were resistant to at least two of the 18 antimicrobials tested. Two isolates (33.3%) were resistant to more than five antimicrobials. Abattoir facilities and slaughter techniques were conducive to carcass contamination. This study highlights how poor hygiene and slaughter practice can result in contaminated meat, which is especially risky in Ethiopia because of the common practice of eating raw meat. We detect multi-resistance to drugs not used in goats, suggesting that drugs used to treat human infections may be the originators of antimicrobial resistance in livestock in this ecosystem. The isolation of multidrug-resistant E. coli O157 from goats from a remote pastoralist system highlights the need for global action on regulating and monitoring antimicrobial use in both human and animal populations.
Isolation of Multidrug-Resistant Escherichia coli O157 from Goats in the Somali Region of Ethiopia: A Cross-Sectional, Abattoir-Based Study

PubMed Central

Dulo, Fitsum; Feleke, Aklilu; Szonyi, Barbara; Fries, Reinhard; Baumann, Maximilian P. O.; Grace, Delia

2015-01-01

Toxigenic Escherichia coli (E. coli) are an important cause of gastroenteritis in developing countries. In Ethiopia, gastroenteritis due to food-borne disease is a leading cause of death. Yet, there is no surveillance for E. coli O157 and little is known about the carriage of this pathogen in Ethiopia’s livestock. This study aimed to assess the prevalence and levels of antimicrobial resistance of E. coli O157 in goat meat, feces, and environmental samples collected at a large abattoir in the Somali region of Ethiopia. The samples were enriched in modified tryptone broth containing novobiocin, and plated onto sorbitol MacConkey agar. Isolates were confirmed using indole test and latex agglutination. Antimicrobial susceptibility testing was conducted using the disk diffusion method. A total of 235 samples, including 93 goat carcass swabs, 93 cecal contents, 14 water, 20 hand, and 15 knife swabs were collected. Overall, six (2.5%) samples were contaminated with E. coli O157 of which two (2.1%) were isolated from cecal contents, three (3.2%) from carcass swabs, and one (7.1%) from water. All isolates were resistant to at least two of the 18 antimicrobials tested. Two isolates (33.3%) were resistant to more than five antimicrobials. Abattoir facilities and slaughter techniques were conducive to carcass contamination. This study highlights how poor hygiene and slaughter practice can result in contaminated meat, which is especially risky in Ethiopia because of the common practice of eating raw meat. We detect multi-resistance to drugs not used in goats, suggesting that drugs used to treat human infections may be the originators of antimicrobial resistance in livestock in this ecosystem. The isolation of multidrug-resistant E. coli O157 from goats from a remote pastoralist system highlights the need for global action on regulating and monitoring antimicrobial use in both human and animal populations. PMID:26561414

Amine control for DUV lithography: identifying hidden sources

NASA Astrophysics Data System (ADS)

Kishkovich, Oleg P.; Larson, Carl E.

2000-06-01

The impact of airborne basic molecular contamination (MB) on the performance of chemically amplified (CA) resist systems has been a long standing problem. Low ppb levels of MB may be sufficient for robust 0.25 micrometer lithography with today's advanced CA resist systems combined with adequate chemical air filtration. However, with minimum CD targets heading below 150 nm, the introduction of new resist chemistries for Next Generation Lithography, and the trend towards thinner resists, the impact of MB at low and sub-ppb levels again becomes a critical manufacturing issue. Maximizing process control at aggressive feature sizes requires that the level of MB be maintained below a certain limit, which depends on such parameters as the sensitivity of the CA resist, the type of production tools, product mix, and process characteristics. Three approaches have been identified to reduce the susceptibility of CA resists to MB: effective chemical air filtration, modifications to resist chemistry/processing and cleanroom protocols involving MB monitoring and removal of MB sources from the fab. The final MB concentration depends on the effectiveness of filtration resources and on the total pollution originating from different sources in and out of the cleanroom. There are many well-documented sources of MB. Among these are: ambient air; polluted exhaust from other manufacturing areas re-entering the cleanroom through make-up air handlers; manufacturing process chemicals containing volatile molecular bases; certain cleanroom construction materials, such as paint and ceiling tiles; and volatile, humidifier system boiler additives (corrosion inhibitors), such as morpholine, cyclohexylamine, and dimethylaminoethanol. However, there is also an indeterminate number of other 'hidden' pollution sources, which are neither obvious nor well-documented. None of these sources are new, but they had little impact on earlier semiconductor manufacturing processes because the contamination levels are low enough that they were tolerable. The purpose of this article is to investigate some of these frequently overlooked sources of basic molecular contamination and to thereby increase the reader's awareness of their potential risks.
Microlith-based Structured Sorbent for Carbon Dioxide, Humidity, and Trace Contaminant Control in Manned Space Habitats

NASA Technical Reports Server (NTRS)

Junaedi, Christian; Roychoudhury, SUbir; Howard, David F.; Perry, Jay L.; Knox, James C.

2011-01-01

To support continued manned space exploration, the development of atmosphere revitalization systems that are lightweight, compact, durable, and power efficient is a key challenge. The systems should be adaptable for use in a variety of habitats and should offer operational functionality to either expel removed constituents or capture them for closedloop recovery. As mission durations increase and exploration goals reach beyond low earth orbit, the need for regenerable adsorption processes for continuous removal of CO2 and trace contaminants from cabin air becomes critical. Precision Combustion, Inc. (PCI) and NASA Marshall (MSFC) have been developing an Engineered Structured Sorbents (ESS) approach based on PCI s patented Microlith technology to meet the requirements of future, extended human spaceflight explorations. This technology offers the inherent performance and safety attributes of zeolite and other sorbents with greater structural integrity, regenerability, and process control, thereby providing potential durability and efficiency improvements over current state-of-the-art systems. The major advantages of the ESS explored in this study are realized through the use of metal substrates to provide structural integrity (i.e., less partition of sorbents) and enhanced thermal control during the sorption process. The Microlith technology also offers a unique internal resistive heating capability that shows potential for short regeneration time and reduced power requirement compared to conventional systems. This paper presents the design, development, and performance results of the integrated adsorber modules for removing CO2, water vapor, and trace chemical contaminants. A related effort that utilizes the adsorber modules for sorption of toxic industrial chemicals is also discussed. Finally, the development of a 4-person two-leg ESS system for continuous CO2 removal is also presented.
Germination of Spores of Astrobiologically Relevant Bacillus Species in High-Salinity Environments.

PubMed

Nagler, Katja; Julius, Christina; Moeller, Ralf

2016-07-01

In times of increasing space exploration and search for extraterrestrial life, new questions and challenges for planetary protection, aiming to avoid forward contamination of different planets or moons with terrestrial life, are emerging. Spore-forming bacteria such as Bacillus species have a high contamination potential due to their spores' extreme resistance, enabling them to withstand space conditions. Spores require liquid water for their conversion into a growing cell (i.e., spore germination and subsequent growth). If present, water on extraterrestrial planets or moons is likely to be closely associated with salts (e.g., in salty oceans or brines), thus constituting high-salinity environments. Spores of Bacillus subtilis can germinate despite very high salt concentrations, although salt stress does exert negative effects on this process. In this study, germination and metabolic reactivation ("outgrowth") of spores of five astrobiologically relevant Bacillus species (B. megaterium, B. pumilus SAFR-032, B. nealsonii, B. mojavensis, and B. vallismortis) in high salinity (≤3.6 M NaCl) were investigated. Spores of different species exhibited different germination and outgrowth capabilities in high salinity, which strongly depended on germination conditions, especially the exact composition of the medium. In this context, a new "universal" germination trigger for Bacillus spores, named KAGE (KCl, L-alanine, D-glucose, ectoine), was identified, which will be very useful for future comparative germination and outgrowth studies on different Bacillus species. Overall, this study yielded interesting new insights on salt stress effects on spore germination and points out the difficulty of predicting the potential of spores to contaminate salty environments on extraterrestrial celestial bodies. Bacillus species-Spores-Germination-High salinity-Salt stress-NaCl-Inhibition. Astrobiology 16, 500-512.
Hazardous particle binder, coagulant and re-aerosolization inhibitor

DOEpatents

Krauter, Paula [Livermore, CA; Zalk, David [San Jose, CA; Hoffman, D Mark [Livermore, CA

2011-04-12

A copolymer and water/ethanol solvent solution capable of binding with airborne contaminants or potential airborne contaminants, such as biological weapon agents or toxic particulates, coagulating as the solvent evaporates, and adhering the contaminants to a surface so as to inhibit the re-suspension of such contaminants. The solution uses a water or ethanol/water mixture for the solvent, and a copolymer having one of several functional group sets so as to have physical and chemical characteristics of high adhesion, low viscosity, low surface tension, negative electrostatic charge, substantially neutral pH, and a low pKa. Use of the copolymer solution prevents re-aerosolization and transport of unwanted, reactive species thus increasing health and safety for personnel charged with decontamination of contaminated buildings and areas.
Hazardous particle binder, coagulant and re-aerosolization inhibitor

DOEpatents

Krauter, Paula; Zalk, David; Hoffman, D. Mark

2012-07-10

A copolymer and water/ethanol solvent solution capable of binding with airborne contaminants or potential airborne contaminants, such as biological weapon agents or toxic particulates, coagulating as the solvent evaporates, and adhering the contaminants to a surface so as to inhibit the re-suspension of such contaminants. The solution uses a water or ethanol/water mixture for the solvent, and a copolymer having one of several functional group sets so as to have physical and chemical characteristics of high adhesion, low viscosity, low surface tension, negative electrostatic charge, substantially neutral pH, and a low pKa. Use of the copolymer solution prevents re-aerosolization and transport of unwanted, reactive species thus increasing health and safety for personnel charged with decontamination of contaminated buildings and areas.
A State-of-the-Art Contamination Effects Research and Test Facility

NASA Technical Reports Server (NTRS)

Olson, Keith R.; Folgner, Kelsey A.; Barrie, James D.; Villahermosa, Randy M.

2008-01-01

In the ongoing effort to better understand various spacecraft contamination phenomena, a new state of the art contamination effects research and test facility was designed, and recently brought on-line at The Aerospace Corporation s Space Materials Laboratory. This high vacuum test chamber employs multiple in-situ analytical techniques, making it possible to study both the qualitative and quantitative aspects of contaminant film formation in the presence or absence of VUV radiation. Adsorption and desorption kinetics, "photo-fixing efficiency", transmission loss of uniform contaminant films, light scatter from non-uniform films, and film morphology have been studied in this facility. This paper describes this new capability in detail and presents data collected from several of the analytical instruments.
Heavy-Metal and Antibiotic Resistance in the Bacterial Flora of Sediments of New York Bight

PubMed Central

Timoney, J. F.; Port, Jennifer; Giles, Janis; Spanier, J.

1978-01-01

The New York Bight extends seaward some 80 to 100 miles (ca. 129 to 161 km) from the Long Island and New Jersey shorelines to the edge of the continental shelf. Over 14 × 106 m3 of sewage sludge, dredge spoils, acid wastes, and cellar dirt are discharged into this area each year. Large populations of Bacillus sp. resistant to 20 μg of mercury per ml were observed in Bight sediments contaminated by these wastes. Resistant Bacillus populations were much greater in sediments containing high concentrations of Hg and other heavy metals than in sediments from areas further offshore where dumping has never been practiced and where heavy-metal concentrations were found to be low. Ampicillin resistance due mainly to β-lactamase production was significantly (P < 0.001) more frequent in Bacillus strains from sediments near the sewage sludge dump site than in similar Bacillus populations from control sediments. Bacillus strains with combined ampicillin and Hg resistances were almost six times as frequent at the sludge dump site as in control sediments. This observation suggests that genes for Hg resistance and β-lactamase production are simultaneously selected for in Bacillus and that heavy-metal contamination of an ecosystem can result in a selection pressure for antibiotic resistance in bacteria in that system. Also, Hg resistance was frequently linked with other heavy-metal resistances and, in a substantial proportion of Bacillus strains, involved reduction to volatile metallic Hg (Hg°). PMID:727779
Effects of mycoplasma contamination on phenotypic expression of mitochondrial mutants in human cells.

PubMed

Doersen, C J; Stanbridge, E J

1981-04-01

HeLa cells sensitive to the mitochondrial protein synthesis inhibitors erythromycin (ERY) and chloramphenicol (CAP) and HeLa variants resistant to the effects of these drugs were purposefully infected with drug-sensitive and -resistant mycoplasma strains. Mycoplasma hyorhinis and the ERY-resistant strain of Mycoplasma orale, MO-ERYr, did not influence the growth of HeLa and ERY-resistant ERY2301 cells in the presence or absence of ERY. M. hyorhinis also did not affect the growth of HeLa and CAP-resistant Cap-2 cells in the presence or absence of CAP. However, both HeLa and Cap-2 cells infected with the CAP-resistant strain of M. hyorhinis, MH-CAPr, were more sensitive to the cytotoxic effect of CAP. This may be due to the glucose dependence of the cells, which was compromised by the increased utilization of glucose by MH-CAPr in these infected cell cultures. In vitro protein synthesis by isolated mitochondria was significantly altered by mycoplasma infection of the various cell lines. A substantial number of mycoplasmas copurified with the mitochondria, resulting in up to a sevenfold increase in the incorporation of [3H]leucine into the trichloroacetic acid-insoluble material. More importantly, the apparent drug sensitivity or resistance of mitochondrial preparations from mycoplasma-infected cells reflected the drug sensitivity or resistance of the contaminating mycoplasmas. These results illustrate the hazards in interpreting mitochondrial protein synthesis data derived from mycoplasma-infected cell lines, particularly putative mitochondrially encoded mutants resistant to inhibitors of mitochondrial protein synthesis.
Application of electromagnetic techniques in survey of contaminated groundwater at an abandoned mine complex in southwestern Indiana, U.S.A.

USGS Publications Warehouse

Brooks, G.A.; Olyphant, G.A.; Harper, D.

1991-01-01

In part of a large abandoned mining complex, electromagnetic geophysical surveys were used along with data derived from cores and monitoring wells to infer sources of contamination and subsurface hydrologic connections between acidic refuse deposits and adjacent undisturbed geologic materials. Electrical resistivity increases sharply along the boundary of an elevated deposit of pyritic coarse refuse, which is highly contaminated and electrically conductive, indicating poor subsurface hydrologic connections with surrounding deposits of fine refuse and undisturbed glacial material. Groundwater chemistry, as reflected in values of specific conductance, also differs markedly across the deposit's boundary, indicating that a widespread contaminant plume has not developed around the coarse refuse in more than 40 yr since the deposit was created. Most acidic drainage from the coarse refuse is by surface runoff and is concentrated around stream channels. Although most of the contaminated groundwater within the study area is concentrated within the surficial refuse deposits, transects of apparent resistivity and phase angle indicate the existence of an anomalous conductive layer at depth (>4 m) in thick alluvial sediments along the northern boundary of the mining complex. Based on knowledge of local geology, the anomaly is interpreted to represent a subsurface connection between the alluvium and a flooded abandoned underground mine. ?? 1991 Springer-Verlag New York Inc.
Application of electromagnetic techniques in survey of contaminated groundwater at an abandoned mine complex in southwestern Indiana, U.S.A.

NASA Astrophysics Data System (ADS)

Brooks, Glenn A.; Olyphant, Greg A.; Harper, Denver

1991-07-01

In part of a large abandoned mining complex, electromagnetic geophysical surveys were used along with data derived from cores and monitoring wells to infer sources of contamination and subsurface hydrologic connections between acidic refuse deposits and adjacent undisturbed geologic materials. Electrical resistivity increases sharply along the boundary of an elevated deposit of pyritic coarse refuse, which is highly contaminated and electrically conductive, indicating poor subsurface hydrologic connections with surrounding deposits of fine refuse and undisturbed glacial material. Groundwater chemistry, as reflected in values of specific conductance, also differs markedly across the deposit's boundary, indicating that a widespread contaminant plume has not developed around the coarse refuse in more than 40 yr since the deposit was created. Most acidic drainage from the coarse refuse is by surface runoff and is concentrated around stream channels. Although most of the contaminated groundwater within the study area is concentrated within the surficial refuse deposits, transects of apparent resistivity and phase angle indicate the existence of an anomalous conductive layer at depth (>4 m) in thick alluvial sediments along the northern boundary of the mining complex. Based on knowledge of local geology, the anomaly is interpreted to represent a subsurface connection between the alluvium and a flooded abandoned underground mine.
The Effect of Substrate Contaminates on the Life of Epoxy Coatings Submerged in Sea Water

DTIC Science & Technology

1991-03-01

contaminants: coal tar, SovaPon, Mare Island and Aquapon . Aquapon is a clear (unpigmented) polyamide epoxy coating. While Aquapon is not normally used for...pigmented coatings. It was found that the Aquapon and coal tar coatings performed similarly, and blistered to the same extent, at the contamination levels...used in the test program. The Sovapon and Mare Island coatings were slightly more resistive to blistering when compared to Aquapon or coal tar but they
Efficiency of hydrogen peroxide in improving disinfection of ICU rooms.

PubMed

Blazejewski, Caroline; Wallet, Frédéric; Rouzé, Anahita; Le Guern, Rémi; Ponthieux, Sylvie; Salleron, Julia; Nseir, Saad

2015-02-02

The primary objective of this study was to determine the efficiency of hydrogen peroxide (H₂O₂) techniques in disinfection of ICU rooms contaminated with multidrug-resistant organisms (MDRO) after patient discharge. Secondary objectives included comparison of the efficiency of a vaporizator (HPV, Bioquell) and an aerosolizer using H₂O₂, and peracetic acid (aHPP, Anios) in MDRO environmental disinfection, and assessment of toxicity of these techniques. This prospective cross-over study was conducted in five medical and surgical ICUs located in one University hospital, during a 12-week period. Routine terminal cleaning was followed by H₂O₂ disinfection. A total of 24 environmental bacteriological samplings were collected per room, from eight frequently touched surfaces, at three time-points: after patient discharge (T0), after terminal cleaning (T1) and after H₂O₂ disinfection (T2). In total 182 rooms were studied, including 89 (49%) disinfected with aHPP and 93 (51%) with HPV. At T0, 15/182 (8%) rooms were contaminated with at least 1 MDRO (extended spectrum β-lactamase-producing Gram-negative bacilli 50%, imipenem resistant Acinetobacter baumannii 29%, methicillin-resistant Staphylococcus aureus 17%, and Pseudomonas aeruginosa resistant to ceftazidime or imipenem 4%). Routine terminal cleaning reduced environmental bacterial load (P <0.001) without efficiency on MDRO (15/182 (8%) rooms at T0 versus 11/182 (6%) at T1; P = 0.371). H₂O₂ technologies were efficient for environmental MDRO decontamination (6% of rooms contaminated with MDRO at T1 versus 0.5% at T2, P = 0.004). Patient characteristics were similar in aHPP and HPV groups. No significant difference was found between aHPP and HPV regarding the rate of rooms contaminated with MDRO at T2 (P = 0.313). 42% of room occupants were MDRO carriers. The highest rate of rooms contaminated with MDRO was found in rooms where patients stayed for a longer period of time, and where a patient with MDRO was hospitalized. The residual concentration of H₂O₂ appears to be higher using aHPP, compared with HPV. H₂O₂ treatment is efficient in reducing MDRO contaminated rooms in the ICU. No significant difference was found between aHPP and HPV regarding their disinfection efficiency.
Geothermal system boundary at the northern edge of Patuha Geothermal Field based on integrated study of volcanostratigraphy, geological field mapping, and cool springs contamination by thermal fluids

NASA Astrophysics Data System (ADS)

Suryantini; Rachmawati, C.; Abdurrahman, M.

2017-12-01

Patuha Geothermal System is a volcanic hydrothermal system. In this type of system, the boundary of the system is often determined by low resistivity (10 ohm.m) anomaly from Magnetotelluric (MT) or DC-Resistivity survey. On the contrary, during geothermal exploration, the system boundary often need to be determined as early as possible even prior of resistivity data available. Thus, a method that use early stage survey data must be developed properly to reduce the uncertainty of the geothermal area extent delineation at the time the geophysical data unavailable. Geological field mapping, volcanostratigraphy analysis and fluid chemistry of thermal water and cold water are the data available at the early stage of exploration. This study integrates this data to delineate the geothermal system boundary. The geological mapping and volcanostratigraphy are constructed to limit the extent of thermal and cold springs. It results that springs in the study area are controlled hydrologically by topography of Patuha Volcanic Crown (complex) or so called PVC, the current geothermal field and Masigit Volcanic Crown (complex) or so called MVC, the dormant volcano not associated with active geothermal system. Some of the cold springs at PVC are contaminated by subsurface steam heated outflow while others are not contaminated. The contaminated cold springs have several characteristics such as higher water temperature than ambient temperature at the time it was measured, higher total disolved solid (TDS), and lower pH. The soluble elements analysis support the early contamination indication by showing higher cation and anion, and positive oxygen shifting of stable isotope of these cool springs. Where as the uncontaminated spring shows similar characteristic with cool springs occur at MVC. The boundary of the system is delineated by an arbitrary line drawn between distal thermal springs from the upflow or contaminated cool springs with the cool uncontaminated springs. This boundary is more or less in agreement with low resisitivity boundary derived from MT and DC resistivity survey. The area defined as part of geothermal area from this method is also validate with drilling data that give high temperature gradient. It suggests that the method use in this study is applicable and reliable.
Assessment of Environmental Contamination with Pathogenic Bacteria at a Hospital Laundry Facility.

PubMed

Michael, Karen E; No, David; Daniell, William E; Seixas, Noah S; Roberts, Marilyn C

2017-11-10

Little is known about exposure to pathogenic bacteria among industrial laundry workers who work with soiled clinical linen. To study worker exposures, an assessment of surface contamination was performed at an industrial laundry facility serving hospitals in Seattle, WA, USA. Surface swab samples (n = 240) from the environment were collected during four site visits at 3-month intervals. These samples were cultured for Clostridium difficile, methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant enterococci (VRE). Voluntary participation of 23 employees consisted of nasal swabs for detection of MRSA, observations during work, and questionnaires. Contamination with all three pathogens was observed in both dirty (laundry handling prior to washing) and clean areas (subsequent to washing). The dirty area had higher odds of overall contamination (≥1 pathogen) than the clean area (odds ratio, OR = 18.0, 95% confidence interval 8.9-36.5, P < 0.001). The odds of contamination were high for each individual pathogen: C. difficile, OR = 15.5; MRSA, OR = 14.8; and VRE, OR = 12.6 (each, P < 0.001). The highest odds of finding surface contamination occurred in the primary and secondary sort areas where soiled linens were manually sorted by employees (OR = 63.0, P < 0.001). The study substantiates that the laundry facility environment can become contaminated by soiled linens. Workers who handle soiled linen may have a higher risk of exposure to C. difficile, MRSA, and VRE than those who handle clean linens. Improved protocols for prevention and reduction of environmental contamination were implemented because of this study. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.
Response of ginger growth to a tetracycline-contaminated environment and residues of antibiotic and antibiotic resistance genes.

PubMed

Liu, Xiaohui; Lv, Yao; Xu, Kun; Xiao, Xinxin; Xi, Beidou; Lu, Shaoyong

2018-06-01

The presence of antibiotic residues in vegetables has been highlighted as a risk to human health; antibiotics not only cause toxic effects to plants but can also induce antibiotic resistance gene (ARG) expression. Using a soil-free approach, this study aimed to explore the response of ginger growth to tetracycline (TC) pollution and to assess the levels of antibiotic residues in different plant organs and the presence of ARGs in the rhizome. Ginger growth in a highly TC-contaminated environment was remarkably inhibited. Photosynthetic parameters, fluorescence parameters, and some physiological indicators (oxidative substances, photosynthetic pigments, enzyme activity, etc.) were negatively influenced by TC contamination. Although the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity levels significantly increased, their effects appear to be limited. The accumulation of TC in the rhizome (28.1 mg kg -1 ) was greater than that in the roots, stem, or leaves. All tested antibiotic resistance genes except for tetL were detectable in the rhizome, and their relative abundance was in the order integron1>tetG > tetA > tetC > tetB > tetM. The level of TC in ginger rhizomes was much higher than the maximum residue limits. The potential dose of TC acquired from the consumption of ginger grown in a highly TC-contaminated environment poses no obvious risk to adults but may be a threat to children. Copyright © 2018 Elsevier Ltd. All rights reserved.
A Comparison of Environmental Contamination by Patients Infected or Colonized with Methicillin-Resistant Staphylococcus aureus or Vancomycin-Resistant Enterococci: A Multicenter Study

PubMed Central

Knelson, Lauren P.; Williams, David A.; Gergen, Maria F.; Rutala, William A.; Weber, David J.; Sexton, Daniel J.; Anderson, Deverick J.

2014-01-01

A total of 1,023 environmental surfaces were sampled from 45 rooms with patients infected or colonized with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE) before terminal room cleaning. Colonized patients had higher median total target colony-forming units (CFU) of MRSA or VRE than did infected patients (median, 25 CFU [interquartile range, 0–106 CFU] vs 0 CFU [interquartile range, 0–29 CFU]; P = .033). PMID:24915217
Contamination removal using various solvents and methodologies

NASA Technical Reports Server (NTRS)

Jeppsen, J. C.

1989-01-01

Critical and non-critical bonding surfaces must be kept free of contamination that may cause potential unbonds. For example, an aft-dome section of a redesigned solid rocket motor that had been contaminated with hydraulic oil did not appear to be sufficiently cleaned when inspected by the optically stimulated electron emission process (Con Scan) after it had been cleaned using a hand double wipe cleaning method. As a result, current and new cleaning methodologies as well as solvent capability in removing various contaminant materials were reviewed and testing was performed. Bonding studies were also done to verify that the cleaning methods used in removing contaminants provide an acceptable bonding surface. The removal of contaminants from a metal surface and the strength of subsequent bonds were tested using the Martin Marietta and double-wipe cleaning methods. Results are reported.
Roles of inter-SWCNT junctions in resistive humidity response

NASA Astrophysics Data System (ADS)

Zhang, Kang; Zou, Jianping; Zhang, Qing

2015-11-01

As a promising chemiresistor for gas sensing, the single-walled carbon nanotube (SWCNT) network has not yet been fully utilized for humidity detection. In this work, it is found that as humidity increases from 10% to 85%, the resistance of as-grown SWCNT networks first decreases and then increases. This non-monotonic resistive response to humidity limits their sensing capabilities. The competition between SWCNT resistance and inter-tube junction resistance changes is then found to be responsible for the non-monotonic resistive humidity responses. Moreover, creating sp3 scattering centers on the SWCNT sidewall by monovalent functionalization of four-bromobenzene diazonium tetrafluoroborate is shown to be capable of eliminating the influence from the inter-tube junctions, resulting in a continuous resistance drop as humidity increases from 10% to 85%. Our results revealed the competing resistive humidity sensing process in as-grown SWCNT networks, which could also be helpful in designing and optimizing as-grown SWCNT networks for humidity sensors and other gas sensors.
Characterization of the maize lipoxygenase gene family in relation to aflatoxin accumulation resistance

Treesearch

Oluwaseun F. Ogunola; Leigh K. Hawkins; Erik Mylroie; Michael V. Kolomiets; Eli Borrego; Juliet D. Tang; Paul W. Williams; Marilyn L. Warburton

2017-01-01

Maize (Zea mays L.) is a globally important staple food crop prone to contamination by aflatoxin, a carcinogenic secondary metabolite produced by the fungus Aspergillus flavus. An efficient approach to reduce accumulation of aflatoxin is the development of germplasm resistant to colonization and toxin...
Genome-Wide Association Mapping of and Aspergillus flavus Aflatoxin Accumulation Resistance in Maize

Treesearch

Marilyn L. Warburton; Juliet D. Tang; Gary L. Windham; Leigh K. Hawkins; Seth C. Murray; Wenwei Xu; Debbie Boykin; Andy Perkins; W. Paul Williams

2015-01-01

Contamination of maize (Zea mays L.) with aflatoxin, produced by the fungus Aspergillus flavus Link, has severe health and economic consequences. Efforts to reduce aflatoxin accumulation in maize have focused on identifying and selecting germplasm with natural host resistance factors, and several maize lines with significantly...

The genomic landscape of rapid, repeated evolutionary rescue from toxic pollution in wild fish

USDA-ARS?s Scientific Manuscript database

Several populations of Atlantic killifish (Fundulus heteroclitus) in contaminated Atlantic coast estuaries have evolved resistance to the toxic effects of PCBs, dioxins, and PAHs. However, the genetic mechanisms of resistance and whether they are shared among populations is not known. We sequenced t...
Effect of manure application rate and timing on the leaching potential of antibiotic resistant bacteria.

USDA-ARS?s Scientific Manuscript database

Antibiotics are used in swine production for therapeutic and growth promotion purposes. Because land application is the most common method of disposing of swine lagoon effluent, there exists the potential threat of contaminating the underlying groundwater with antimicrobial-resistant bacteria (ARB) ...
Evaluation of the expression genes associated with resistance to Aspergillus flavus colonization and aflatoxin production in different maize lines.

USDA-ARS?s Scientific Manuscript database

Aflatoxins are carcinogenic toxic compounds produced by Aspergillus flavus during infection of crops including maize (Zea mays L.). Contamination of maize with aflatoxin is exacerbated by late season drought stress. Previous studies have implicated numerous resistance-associated proteins (RAPs) that...
46 CFR 119.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2011 CFR

2011-10-01

... tubing or hose having high resistance to salt water, petroleum oils, heat and vibration, may be used... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
46 CFR 119.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2014 CFR

2014-10-01

... tubing or hose having high resistance to salt water, petroleum oils, heat and vibration, may be used... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
46 CFR 182.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2011 CFR

2011-10-01

... hose having high resistance to salt water, petroleum oils, heat and vibration, may be used. Such hose... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
46 CFR 182.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2012 CFR

2012-10-01

... hose having high resistance to salt water, petroleum oils, heat and vibration, may be used. Such hose... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
46 CFR 119.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2012 CFR

2012-10-01

... tubing or hose having high resistance to salt water, petroleum oils, heat and vibration, may be used... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
46 CFR 119.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2013 CFR

2013-10-01

... tubing or hose having high resistance to salt water, petroleum oils, heat and vibration, may be used... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
46 CFR 182.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2013 CFR

2013-10-01

... hose having high resistance to salt water, petroleum oils, heat and vibration, may be used. Such hose... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
46 CFR 182.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2014 CFR

2014-10-01

... hose having high resistance to salt water, petroleum oils, heat and vibration, may be used. Such hose... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
46 CFR 182.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2010 CFR

2010-10-01

... hose having high resistance to salt water, petroleum oils, heat and vibration, may be used. Such hose... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
46 CFR 119.450 - Vent pipes for fuel tanks.

Code of Federal Regulations, 2010 CFR

2010-10-01

... tubing or hose having high resistance to salt water, petroleum oils, heat and vibration, may be used... installed or equipped to prevent the accidental contamination of the fuel by water under normal operating... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at...
Genetic characterization of the maize lipoxygenase gene family in relation to aflatoxin accumuation resistance.

USDA-ARS?s Scientific Manuscript database

Maize (Zea mays L.) is a globally important staple food crop. It is prone to contamination by aflatoxin, a secondary carcinogenic metabolite produced by the fungus Aspergillus flavus. An efficient approach to combat the accumulation of aflatoxin is the development of germplasm resistant to infection...
Identification of Maize Breeding Markers through Investigations of Proteins Associated with Aflatoxin-Resistance

USDA-ARS?s Scientific Manuscript database

The goal of a collaborative research project between International Institute of Tropical Agriculture (IITA) in Nigeria and ARS-Southern Regional Research Center (SRRC) in New Orleans is to develop maize inbred lines with resistance against aflatoxin contamination by Aspergillus flavus. A second goal...
Drought stress and aflatoxin contamination: Transcriptional responses of Aspergillus flavus to oxidative stress are related to stress tolerance and aflatoxin production capability

USDA-ARS?s Scientific Manuscript database

Oilseed crops such as maize and peanut are staple food crops which are vital for global food security. The contamination of these crops with carcinogenic aflatoxins during infection by Aspergillus flavus under drought stress conditions is a serious threat to the safety of these commodities. In order...
Use of amphiphilic triblock copolymers for enhancing removal efficiency of organic pollutant from contaminated media

NASA Astrophysics Data System (ADS)

Lee, Jun Hyup; Lee, Byungsun; Son, Intae; Kim, Jae Hong; Kim, Chunho; Yoo, Ji Yong; Wu, Jong-Pyo; Kim, Younguk

2015-11-01

We have studied amphiphilic triblock copolymers poly(ethylene glycol)- b-poly(propylene glycol)- b-poly(ethylene glycol) (PEG- b-PPG- b-PEG) and poly(propylene glycol)- b-poly(ethylene glycol)- b-poly(propylene glycol) (PPG- b-PEG- b-PPG) as possible substitutes for sodium dodecyl sulfate as anionic surfactants for the removal of hydrophobic contaminants. The triblock copolymers were compared with sodium dodecyl sulfate in terms of their abilities to remove toluene as hydrophobic contaminant in fuel, and the effects of polymer structure, PEG content, and concentration were studied. The PEG- b-PPG- b-PEG copolymer containing two hydrophilic PEG blocks was more effective for the removal of hydrophobic contaminant at extremely high concentration. We also measured the removal capabilities of the triblock copolymers having various PEG contents and confirmed that removal capability was greatest at 10% PEG content regardless of polymer structure. As with sodium dodecyl sulfate, the removal efficiency of a copolymer has a positive correlation with its concentration. Finally, we proposed the amphiphilic triblock copolymer of PPG- b-PEG- b-PPG bearing 10% PEG content that proved to be the most effective substitute for sodium dodecyl sulfate.
Prevalence and antibiotic susceptibility profiles of Listeria monocytogenes contamination of chicken flocks and meat in Oyo State, south-western Nigeria: Public health implications.

PubMed

Ishola, O O; Mosugu, J I; Adesokan, H K

2016-09-01

Food contamination with Listeria monocytogenes is on the increase posing threats to public health with growing trends in food products recalls due to suspected Listeria contamination. We conducted a cross-sectional study to determine the prevalence and antibiotic susceptibility profiles of Listeria monocytogenes (Lm) among 71 randomly selected poultry farms in Oyo State, Nigeria. A total of 450 samples comprising cloacal swabs (426) and randomly selected dressed chicken meat (24) were cultured for Lm isolation using BrillianceTM Selective Listeria Agar with antibiotics and microbial load count with Nutrient Agar. Further identification was done using microscopic, biochemical characterization and antibiotic sensitivity tests. Data were analysed using bivariate analysis and student t-test. An overall prevalence of 91.8% Lm contamination was obtained comprising 91.5% (390/426) in cloacal swabs and 95.8% (23/24) in meat. The prevalence of Lm in cloacal samples was significantly associated with poultry type (p = 0.008) and breed (p = 0.000. In addition, all the flocks had at least one positive sample yielding 100% flock prevalence. Antibiotic sensitivity test revealed that most of the isolates were resistant to common antibiotics like Ampicillin-cloxacillin and cefuroxime. The results revealed a high level of contamination with Lm in the poultry flock and meat and the observed resistance to most common antibiotics has implications for future disease control as well as public health. There is need to step up routine screening of food animal products for Listeria contamination as well as measures towards reducing such contaminations.
Inoculation Techniques in the Field Screening and Selection for Corn Inbred and Hybirds Resistance to Preharvest Aflatoxin Contamination

USDA-ARS?s Scientific Manuscript database

Preharvest aflatoxin contamination of grain grown on the U.S. Southeastern Coast Plain is provoked and aggravated by both biotic and abiotic stress factors that influence infection by Asperigillus flavus. An array of arthropod species contribute to the dispersal of this fungus as they attack and fee...
Limitations of the efficacy of surface disinfection in the healthcare setting.

PubMed

Williams, Gareth J; Denyer, Stephen P; Hosein, Ian K; Hill, Dylan W; Maillard, Jean-Yves

2009-06-01

We examined the efficacy of 2 commercially available wipes to effectively remove, kill, and prevent the transfer of both methicillin-resistant and methicillin-susceptible Staphylococcus aureus from contaminated surfaces. Although wipes play a role in decreasing the number of pathogenic bacteria from contaminated surfaces, they can potentially transfer bacteria to other surfaces if they are reused.

Diagnostic Tools for Performance Evaluation of Innovative In-Situ Remediation Technologies at Chlorinated Solvent-Contaminated Sites

DTIC Science & Technology

2011-07-01

fluid resistivity , temperature logging, and flow metering at other sites that typically indicated only two or three active fractures in each hole...was consistent with results of conventional borehole fluid resistivity , temperature logging, and flow metering at other sites that typically indicated...following tests were performed in each boundary monitoring well: ■ Gamma Ray; ■ Spontaneous Potential (SP); ■ Single Point Resistance (SPR
Blocking Filters with Enhanced Throughput for X-Ray Microcalorimetry

NASA Technical Reports Server (NTRS)

Grove, David; Betcher, Jacob; Hagen, Mark

2012-01-01

New and improved blocking filters (see figure) have been developed for microcalorimeters on several mission payloads, made of high-transmission polyimide support mesh, that can replace the nickel mesh used in previous blocking filter flight designs. To realize the resolution and signal sensitivity of today s x-ray microcalorimeters, significant improvements in the blocking filter stack are needed. Using high-transmission polyimide support mesh, it is possible to improve overall throughput on a typical microcalorimeter such as Suzaku s X-ray Spectrometer by 11%, compared to previous flight designs. Using polyimide to replace standard metal mesh means the mesh will be transparent to energies 3 keV and higher. Incorporating polyimide s advantageous strength-to-weight ratio, thermal stability, and transmission characteristics permits thinner filter materials, significantly enhancing through - put. A prototype contamination blocking filter for ASTRO-H has passed QT-level acoustic testing. Resistive traces can also be incorporated to provide decontamination capability to actively restore filter performance in orbit.
Characterization of the extremely arsenic-resistant Brevibacterium linens strain AE038-8 isolated from contaminated groundwater in Tucuman, Argentina

DOE PAGES

Maizel, Daniela; Blum, Jodi Switzer; Ferrero, Marcela A.; ...

2015-12-10

Brevibacterium linens AE038-8, isolated from As-contaminated groundwater in Tucumán (Argentina), is highly resistant to arsenic oxyanions, being able to tolerate up to 1 M As(V) and 75 mM As(III) in a complex medium. Strain AE038-8 was also able to reduce As(V) to As(III) when grown in complex medium but paradoxically it could not do this in a defined minimal medium with sodium acetate and ammonium sulfate as carbon and nitrogen sources, respectively. No oxidation of As(III) to As(V) was observed under any conditions. Here, three copies of the ars operon comprising arsenic resistance genes were found on B. linens AE038-8more » genome. In addition to the well known arsC, ACR3 and arsR, two copies of the arsO gene of unknown function were detected.« less
Characterization of the extremely arsenic-resistant Brevibacterium linens strain AE038-8 isolated from contaminated groundwater in Tucuman, Argentina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maizel, Daniela; Blum, Jodi Switzer; Ferrero, Marcela A.

Brevibacterium linens AE038-8, isolated from As-contaminated groundwater in Tucumán (Argentina), is highly resistant to arsenic oxyanions, being able to tolerate up to 1 M As(V) and 75 mM As(III) in a complex medium. Strain AE038-8 was also able to reduce As(V) to As(III) when grown in complex medium but paradoxically it could not do this in a defined minimal medium with sodium acetate and ammonium sulfate as carbon and nitrogen sources, respectively. No oxidation of As(III) to As(V) was observed under any conditions. Here, three copies of the ars operon comprising arsenic resistance genes were found on B. linens AE038-8more » genome. In addition to the well known arsC, ACR3 and arsR, two copies of the arsO gene of unknown function were detected.« less
A new nuclide transport model in soil in the GENII-LIN health physics code

NASA Astrophysics Data System (ADS)

Teodori, F.

2017-11-01

The nuclide soil transfer model, originally included in the GENII-LIN software system, was intended for residual contamination from long term activities and from waste form degradation. Short life nuclides were supposed absent or at equilibrium with long life parents. Here we present an enhanced soil transport model, where short life nuclide contributions are correctly accounted. This improvement extends the code capabilities to handle incidental release of contaminant to soil, by evaluating exposure since the very beginning of the contamination event, before the radioactive decay chain equilibrium is reached.
Precipitation influences pathogenic bacteria and antibiotic resistance gene abundance in storm drain outfalls in coastal sub-tropical waters.

PubMed

Ahmed, Warish; Zhang, Qian; Lobos, Aldo; Senkbeil, Jacob; Sadowsky, Michael J; Harwood, Valerie J; Saeidi, Nazanin; Marinoni, Oswald; Ishii, Satoshi

2018-07-01

Stormwater contamination can threaten the health of aquatic ecosystems and human exposed to runoff via nutrient and pathogen influxes. In this study, the concentrations of 11 bacterial pathogens and 47 antibiotic resistance genes (ARGs) were determined by using high-throughput microfluidic qPCR (MFQPCR) in several storm drain outfalls (SDOs) during dry and wet weather in Tampa Bay, Florida, USA. Data generated in this study were also compared with the levels of fecal indicator bacteria (FIB) and sewage-associated molecular markers (i.e., Bacteroides HF183 and crAssphage markers) in same SDOs collected in a recent study (Ahmed et al., 2018). Concentration of FIB, sewage-associated markers, bacterial pathogens and many ARGs in water samples were relatively high and SDOs may be potentially hotspots for microbial contamination in Tampa Bay. Mean concentrations of culturable E. coli and Enterococcus spp. were tenfold higher in wet compared to dry weather. The majority of microbiological contaminants followed this trend. E. coli eaeA, encoding the virulence factor intimin, was correlated with levels of 20 ARGs, and was more frequently detected in wet weather than dry weather samples. The bla KPC gene associated with carbapenem resistant Enterobacteriaceae and the beta-lactam resistant gene (bla NPS ) were only detected in wet weather samples. Frequency of integron genes Intl2 and Intl3 detection increased by 42% in wet weather samples. Culturable E. coli and Enterococcus spp. significantly correlated with 19 of 47 (40%) ARG tested. Sewage-associated markers crAssphage and HF183 significantly correlated (p < 0.05) with the following ARGs: intl1, sul1, tet(M), ampC, mexB, and tet(W). The presence of sewage-associated marker genes along with ARGs associated with sewage suggested that aging sewage infrastructure contributed to contaminant loading in the Bay. Further research should focus on collecting spatial and temporal data on the microbiological contaminants especially viruses in SDOs. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.
Role of Fungicides, Application of Nozzle Types, and the Resistance Level of Wheat Varieties in the Control of Fusarium Head Blight and Deoxynivalenol

PubMed Central

Mesterházy, Ákos; Tóth, Beáta; Varga, Monika; Bartók, Tibor; Szabó-Hevér, Ágnes; Farády, László; Lehoczki-Krsjak, Szabolcs

2011-01-01

Fungicide application is a key factor in the control of mycotoxin contamination in the harvested wheat grain. However, the practical results are often disappointing. In 2000-2004, 2006-2008 and 2007 and 2008, three experiments were made to test the efficacy of fungicide control on Fusarium Head Blight (FHB) in wheat and to find ways to improve control of the disease and toxin contamination. In a testing system we have used for 20 years, tebuconazole and tebuconazole + prothioconazole fungicides regularly reduced symptoms by about 80% with a correlating reduction in toxin contamination. Averages across the years normally show a correlation of r = 0.90 or higher. The stability differences (measured by the stability index) between the poorest and the best fungicides are about 10 or more times, differing slightly in mycotoxin accumulation, FHB index (severity) and Fusarium damaged kernels (FDK). The weak fungicides, like carbendazim, were effective only when no epidemic occurred or epidemic severity was at a very low level. Similar fungicide effects were seen on wheat cultivars which varied in FHB resistance. In this study, we found three fold differences in susceptibility to FHB between highly susceptible and moderately resistant cultivars when treated with fungicides. In the moderately resistant cultivars, about 50% of the fungicide treatments lowered the DON level below the regulatory limit. In the most susceptible cultivars, all fungicides failed to reduce mycotoxin levels low enough for grain acceptance, in spite of the fact that disease was significantly reduced. The results correlated well with the results of the large-scale field tests of fungicide application at the time of natural infection. The Turbo FloodJet nozzle reduced FHB incidence and DON contamination when compared to the TeeJet XR nozzle. Overall, the data suggest that significant decreases in FHB incidence and deoxynivalenol contamination in field situations are possible with proper fungicide applications. Additionally, small plot tests can be used to evaluate the quality of the field disease and toxin production. PMID:22174980
Engineering Plant-Microbe Symbiosis for Rhizoremediation of Heavy Metals

PubMed Central

Wu, Cindy H.; Wood, Thomas K.; Mulchandani, Ashok; Chen, Wilfred

2006-01-01

The use of plants for rehabilitation of heavy-metal-contaminated environments is an emerging area of interest because it provides an ecologically sound and safe method for restoration and remediation. Although a number of plant species are capable of hyperaccumulation of heavy metals, the technology is not applicable for remediating sites with multiple contaminants. A clever solution is to combine the advantages of microbe-plant symbiosis within the plant rhizosphere into an effective cleanup technology. We demonstrated that expression of a metal-binding peptide (EC20) in a rhizobacterium, Pseudomonas putida 06909, not only improved cadmium binding but also alleviated the cellular toxicity of cadmium. More importantly, inoculation of sunflower roots with the engineered rhizobacterium resulted in a marked decrease in cadmium phytotoxicity and a 40% increase in cadmium accumulation in the plant root. Owing to the significantly improved growth characteristics of both the rhizobacterium and plant, the use of EC20-expressing P. putida endowed with organic-degrading capabilities may be a promising strategy to remediate mixed organic-metal-contaminated sites. PMID:16461658
Emergency drinking water treatment during source water pollution accidents in China: origin analysis, framework and technologies.

PubMed

Zhang, Xiao-Jian; Chen, Chao; Lin, Peng-Fei; Hou, Ai-Xin; Niu, Zhang-Bin; Wang, Jun

2011-01-01

China has suffered frequent source water contamination accidents in the past decade, which has resulted in severe consequences to the water supply of millions of residents. The origins of typical cases of contamination are discussed in this paper as well as the emergency response to these accidents. In general, excessive pursuit of rapid industrialization and the unreasonable location of factories are responsible for the increasing frequency of accidental pollution events. Moreover, insufficient attention to environmental protection and rudimentary emergency response capability has exacerbated the consequences of such accidents. These environmental accidents triggered or accelerated the promulgation of stricter environmental protection policy and the shift from economic development mode to a more sustainable direction, which should be regarded as the turning point of environmental protection in China. To guarantee water security, China is trying to establish a rapid and effective emergency response framework, build up the capability of early accident detection, and develop efficient technologies to remove contaminants from water.
Capabilities of Seven Species of Aquatic Macrophytes for Phytoremediation of Pentachlorophenol Contaminated Sediment

NASA Astrophysics Data System (ADS)

Zhao, Liangyuan; Guo, Weijie; Li, Qingyun; Li, Huan; Zhao, Weihua; Cao, Xiaohuan

2017-01-01

Sediments are regarded as the ultimate sink of pentachlorophenol(PCP) in aquatic environment, and capabilities of seven species of aquatic macrophytes for remediating PCP contaminated sediment were investigated. Seven species of aquatic macrophytes could significantly accelerate the degradation of PCP in sediments. Among all, canna indica L., Acorus calamus L. and Iris tectorum Maxim. can be used as efficient alternative plants for remediation of PCP contaminated sediment, which attained 98%, 92% and 88% of PCP removal in sediments, respectively. PCP was detected only in root tissues and the uptake was closely related to the root lipid contents of seven plants. The presence of seven aquatic macrophytes significantly increased microbial populations and the activities of dehydrogenase compared with control sediments, indicating that rhizosphere microorganism played important role in the remediation process. In conclusion, seven species of aquatic macrophytes may act as promising tools for the PCP phytoremediation in aquatic environment, especially Canna indica L., Acorus calamus L. and Iris tectorum Maxim.
System description for DART (Decision Analysis for Remediation Technologies)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nonte, J.; Bolander, T.; Nickelson, D.

1997-09-01

DART is a computer aided system populated with influence models to determine quantitative benefits derived by matching requirements and technologies. The DART database is populated with data from over 900 DOE sites from 10 Field Offices. These sites are either source terms, such as buried waste pits, or soil or groundwater contaminated plumes. The data, traceable to published documents, consists of site-specific data (contaminants, area, volume, depth, size, remedial action dates, site preferred remedial option), problems (e.g., offsite contaminant plume), and Site Technology Coordinating Group (STCG) need statements (also contained in the Ten-Year Plan). DART uses this data to calculatemore » and derive site priorities, risk rankings, and site specific technology requirements. DART is also populated with over 900 industry and DOE SCFA technologies. Technology capabilities can be used to match technologies to waste sites based on the technology`s capability to meet site requirements and constraints. Queries may be used to access, sort, roll-up, and rank site data. Data roll-ups may be graphically displayed.« less
Effects of carbon/graphite fiber contamination on high voltage electrical insulation

NASA Technical Reports Server (NTRS)

Garrity, T.; Eichler, C.

1980-01-01

The contamination mechanics and resulting failure modes of high voltage electrical insulation due to carbon/graphite fibers were examined. The high voltage insulation vulnerability to carbon/graphite fiber induced failure was evaluated using a contamination system which consisted of a fiber chopper, dispersal chamber, a contamination chamber, and air ducts and suction blower. Tests were conducted to evaluate the effects of fiber length, weathering, and wetness on the insulator's resistance to carbon/graphite fibers. The ability of nuclear, fossil, and hydro power generating stations to maintain normal power generation when the surrounding environment is contaminated by an accidental carbon fiber release was investigated. The vulnerability assessment included only the power plant generating equipment and its associated controls, instrumentation, and auxiliary and support systems.
Transformation of heavy metal fractionation under changing environments: a case study of a drainage system in an e-waste dismantling community.

PubMed

Damrongsiri, Seelawut

2018-04-01

The change in environmental conditions during the transportation of contaminated soil and sediment was expected to affect the transformation of heavy metal fractionation. This study disclosed the serious contamination of copper (Cu), lead (Pb), and zinc (Zn) in the sewer sediment of an e-waste dismantling community in Thailand which may be caused by flushed contaminated soil and e-waste fragments. Two environmental conditions were simulated to observe the transformation of heavy metal fractionation. The anoxic sewer condition was induced using high substrate and sulfate in a closed container. The aeration of anoxic contaminated sediment was applied to simulate the transformation to an oxidative environment. The BCR sequential extraction was applied for heavy metal fractionation in this study. The study results exhibited that when heavy metal contaminated soil was transferred into this induced anoxic condition, fractionation was redistributed based on the chemical change of system that tends to be associated into F3 (oxidizable fraction) > F2 (reducible fraction) > F1 (acid soluble/exchangeable fraction). Cu exhibited the outstanding capability association to F3. The iron sulfide was not observed as usual due to its lower capability than Cu, Pb, and Zn. When contaminated sediment was transported to a more oxidative environment, the heavy metals fractionation would be redistributed again among those new environment media. It is noteworthy that F3 of Cu was stable even in oxic conditions. F2 of Fe was not developed by this oxic condition, possibly because its dehydration process was limited. The redistribution under an oxic environment became F1 > F2 > F3 indicating their more available form. This transformation was imperative and should be taken into account in heavy metal contaminated site management and control.
[New aspects of safety assessment and food contamination with antibiotics of tetracycline group in the light of harmonization of hygienic standards in Russia and Customs Union with the international standards].

PubMed

Onishchenko, G G; Sheveleva, S A; Khotimchenko, S A

2012-01-01

To address the issue of harmonization of Russian MRLs for tetracycline in food and on the basis of the tasks of preserving the value of hygienic standard for the more restrictive level than similar standards of the Codex Alimentarius Commission in this survey we analyzed the evidences of the negative effects of subingibitory amounts of these antibiotics (lying below the MIC for clinically relevant microorganisms). The inadequacy of the microbiological JECFA ADI and the necessity of using of methodology of analyzing the effects of biological active substances in small doses for assessing the risk of food contamination of tetracycline subingibitory concentrations were demonstrated. Current scientific information on the functions of antibiotics as signaling molecules in the microbial world and the role of tetracycline as a leading factor in the regulation of transcription in microorganisms and activation of the horizontal transfer of resistance genes transferred to the family of conjugative transposons Tn916-Tn1545 also was reviewed in paper. Evidence-based data regarding the basic contribution of subingibitory concentrations of tetracycline in the spread of worst transmissible type of antibiotic resistance and the formation of new pathogens, associated with it, are represented. To reduce the risk of direct adverse effects on microbial ecosystem in the human body and its habitat, and to minimize the indirect risk of new infections, the necessity of saving the current Russian level residues of tetracycline (< or = 0.01 mg/kg of product), which is low by contrast to the Codex MRLs (< or = 0.1-1.2 mg/kg), was proved. Tetracycline concentrations in food, regulated in Russian Federation, below 0.1 MIC for clinically significant microorganisms which aren't capable to initiation of the above described negative changes.
Modeling Degradation Product Partitioning in Chlorinated-DNAPL Source Zones

NASA Astrophysics Data System (ADS)

Boroumand, A.; Ramsburg, A.; Christ, J.; Abriola, L.

2009-12-01

Metabolic reductive dechlorination degrades aqueous phase contaminant concentrations, increasing the driving force for DNAPL dissolution. Results from laboratory and field investigations suggest that accumulation of cis-dichloroethene (cis-DCE) and vinyl chloride (VC) may occur within DNAPL source zones. The lack of (or slow) degradation of cis-DCE and VC within bioactive DNAPL source zones may result in these dechlorination products becoming distributed among the solid, aqueous, and organic phases. Partitioning of cis-DCE and VC into the organic phase may reduce aqueous phase concentrations of these contaminants and result in the enrichment of these dechlorination products within the non-aqueous phase. Enrichment of degradation products within DNAPL may reduce some of the advantages associated with the application of bioremediation in DNAPL source zones. Thus, it is important to quantify how partitioning (between the aqueous and organic phases) influences the transport of cis-DCE and VC within bioactive DNAPL source zones. In this work, abiotic two-phase (PCE-water) one-dimensional column experiments are modeled using analytical and numerical methods to examine the rate of partitioning and the capacity of PCE-DNAPL to reversibly sequester cis-DCE. These models consider aqueous-phase, nonaqueous phase, and aqueous plus nonaqueous phase mass transfer resistance using linear driving force and spherical diffusion expressions. Model parameters are examined and compared for different experimental conditions to evaluate the mechanisms controlling partitioning. Biot number, a dimensionless number which is an index of the ratio of the aqueous phase mass transfer rate in boundary layer to the mass transfer rate within the NAPL, is used to characterize conditions in which either or both processes are controlling. Results show that application of a single aqueous resistance is capable to capture breakthrough curves when DNAPL is distributed in porous media as low-saturation ganglia, while diffusion within the DNAPL should be considered for larger NAPL pools. These results offer important insights to the monitoring and interpretation of bioremediation strategies employed within DNAPL source zones.
Providencia in retail meats from Guangzhou, China and Osaka, Japan: prevalence, antimicrobial resistance and characterization of classes 1, 2 and 3 integrons.

PubMed

DI, Huiling; Liang, Sisi; Li, Qingyang; Shi, Lei; Shima, Ayaka; Meng, Hecheng; Yan, He; Yamasaki, Shinji

2018-05-18

Bacteria of the genus Providencia are opportunistic pathogens of clinical significance due to their association with diarrhea and urinary tract infections. The present study was conducted to examine the prevalence and antimicrobial resistance of Providencia spp. in retail meats sold in Guangzhou, China and Osaka, Japan. Out of 158 meat samples including beef, pork and chicken, 67 Providencia (42%) belonging to four species viz., P. alcalifaciens, P. rustigianii, P. stuartii and P. rettgeri were isolated, and most of them were resistant to tetracycline (91%) followed by ampicillin (69%) and streptomycin (49%). Of 67 isolates, 29 (43%) were MDR, which is defined to be resistant to more than three classes of antimicrobials. No statistically significant differences were observed between Chinese and Japanese retail meat samples regarding contamination rate of Providencia spp. as well as frequency of the antimicrobial resistance of the isolates including MDR. Class 1 and/or class 2 integrons were detected in six of the eight isolates that were resistant to more than 4 antimicrobials, however none of the isolates harbored class 3 integron. A P. rustigianii harboring the bla OXA-10 gene was isolated, which is the first report of Providencia with bla OXA-10 gene of food origin. These data suggest that retail meats in China and Japan are substantially contaminated with Providencia spp., which displayed a high frequency of antimicrobial resistance, and establishing the surveillance of Providencia spp., especially antimicrobial resistant one, in retail meats is imperative.
The consequences of resistance training for movement control in older adults.

PubMed

Barry, Benjamin K; Carson, Richard G

2004-07-01

Older adults who undertake resistance training are typically seeking to maintain or increase their muscular strength with the goal of preserving or improving their functional capabilities. The extent to which resistance training adaptations lead to improved performance on tasks of everyday living is not particularly well understood. Indeed, studies examining changes in functional task performance experienced by older adults following periods of resistance training have produced equivocal findings. A clear understanding of the principles governing the transfer of resistance training adaptations is therefore critical in seeking to optimize the prescription of training regimes that have as their aim the maintenance and improvement of functional movement capacities in older adults. The degenerative processes that occur in the aging motor system are likely to influence heavily any adaptations to resistance training and the subsequent transfer to functional task performance. The resulting characteristics of motor behavior, such as the substantial decline in the rate of force development and the decreased steadiness of force production, may entail that specialized resistance training strategies are necessary to maximize the benefits for older adults. In this review, we summarize the alterations in the neuromuscular system that are responsible for the declines in strength, power, and force control, and the subsequent deterioration in the everyday movement capabilities of older adults. We examine the literature concerning the neural adaptations that older adults experience in response to resistance training, and consider the readiness with which these adaptations will improve the functional movement capabilities of older adults.
Functional Expression of a Bacterial Heavy Metal Transporter in Arabidopsis Enhances Resistance to and Decreases Uptake of Heavy Metals1[w

PubMed Central

Lee, Joohyun; Bae, Hyunju; Jeong, Jeeyon; Lee, Jae-Yun; Yang, Young-Yell; Hwang, Inhwan; Martinoia, Enrico; Lee, Youngsook

2003-01-01

Large parts of agricultural soil are contaminated with lead (Pb) and cadmium (Cd). Although most environments are not heavily contaminated, the low levels observed nonetheless pose a high risk of heavy metal accumulation in the food chain. Therefore, approaches to develop plants with reduced heavy metal uptake are important. Recently, many transgenic plants with increased heavy metal resistance and uptake of heavy metals were developed for the purpose of phytoremediation. However, to reduce heavy metal in the food chain, plants that transfer less heavy metals to the shoot are required. We tested whether an Escherichia coli gene, ZntA, which encodes a Pb(II)/Cd(II)/Zn(II) pump, could be useful for developing plants with reduced heavy metal content. Yeast cells transformed with this gene had improved resistance to Pb(II) and Cd(II). In Arabidopsis plants transformed with ZntA, ZntA was localized at the plasma membrane and improved the resistance of the plants to Pb(II) and Cd(II). The shoots of the transgenic plants had decreased Pb and Cd content. Moreover, the transgenic protoplasts showed lower accumulation of Cd and faster release of preloaded Cd than wild-type protoplasts. These results show that a bacterial transporter gene, ZntA, can be functionally expressed in plant cells, and that that it may be useful for the development of crop plants that are safe from heavy metal contamination. PMID:14512517
Methicillin-resistant Staphylococcus aureus in public transportation vehicles (buses): another piece to the epidemiologic puzzle.

PubMed

Lutz, Jonathan K; van Balen, Joany; Crawford, John Mac; Wilkins, John R; Lee, Jiyoung; Nava-Hoet, Rocio C; Hoet, Armando E

2014-12-01

Little is known about the occurrence and epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in public transportation in the United States. This research sought to determine the background prevalence and phenotypic and genotypic characteristics of MRSA strains circulating on buses from a large, metropolitan transportation agency. Electrostatic wipes were used to collect 237 surface samples from 40 buses randomly selected from July-October 2010. Six samples were collected from each bus immediately postservice and before any cleaning and disinfection. Positive isolates were analyzed for antibiotic resistance, staphylococcal cassette chromosome mec (SCCmec) type, and pulsed-field gel electrophoresis; and potential epidemiologic factors were examined. Of the buses, 68% (27/40) were contaminated with S aureus, and 63% (25/40) were contaminated with MRSA. Seats and seat rails were the surfaces most frequently contaminated, followed by the back door and stanchions. Most (62.9%) of the MRSA isolates were classified as community-associated MRSA clones (SCCmec type IV), and 22.9% were health care-associated MRSA clones (SCCmec type II). Of the MRSA strains, 65% (5/20) were multidrug resistant. MRSA was frequently isolated from commonly touched surfaces in buses serving both hospital and community routes. Phenotypic and genotypic analysis demonstrated that buses may be effective mixing vessels for MRSA strains of both community and health care-associated origin. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Radiation resistances and decontamination of common pathogenic bacteria contaminated in white scar oyster ( Crassostrea belcheri) in Thailand

NASA Astrophysics Data System (ADS)

Thupila, Nunticha; Ratana-arporn, Pattama; Wilaipun, Pongtep

2011-07-01

In Thailand, white scar oyster ( Crassostrea belcheri) was ranked for premium quality, being most expensive and of high demand. This oyster is often eaten raw, hence it may pose health hazards to consumers when contaminated with food-borne pathogens. As limited alternative methods are available to sterilize the oyster while preserving the raw characteristic, irradiation may be considered as an effective method for decontamination. In this study, the radiation resistance of pathogenic bacteria commonly contaminating the oyster and the optimum irradiation doses for sterilization of the most radiation resistant bacteria were investigated. The radiation decimal reduction doses ( D10) of Salmonella Weltevreden DMST 33380, Vibrio parahaemolyticus ATCC 17802 and Vibrio vulnificus DMST 5852 were determined in broth culture and inoculated oyster homogenate. The D10 values of S. Weltevreden, V. parahaemolyticus and V. vulnificus in broth culture were 0.154, 0.132 and 0.059 kGy, while those of inoculated oyster homogenate were 0.330, 0.159 and 0.140 kGy, respectively. It was found that among the pathogens tested, S. Weltevreden was proved to be the most resistant species. An irradiation dose of 1.5 kGy reduced the counts of 10 5 CFU/g S. Weltevreden inoculated in oyster meat to an undetectable level. The present study indicated that a low-dose irradiation can improve the microbial quality of oyster and further reduce the risks from the food-borne pathogens without adversely affecting the sensory attributes.

Antibiotic resistance is widespread in urban aquatic environments of Rio de Janeiro, Brazil.

PubMed

Coutinho, Felipe H; Silveira, Cynthia B; Pinto, Leonardo H; Salloto, Gigliola R B; Cardoso, Alexander M; Martins, Orlando B; Vieira, Ricardo P; Clementino, Maysa M

2014-10-01

Bacterial resistance to antibiotics has become a public health issue. Over the years, pathogenic organisms with resistance traits have been studied due to the threat they pose to human well-being. However, several studies raised awareness to the often disregarded importance of environmental bacteria as sources of resistance mechanisms. In this work, we analyze the diversity of antibiotic-resistant bacteria occurring in aquatic environments of the state of Rio de Janeiro, Brazil, that are subjected to distinct degrees of anthropogenic impacts. We access the diversity of aquatic bacteria capable of growing in increasing ampicillin concentrations through 16S rRNA gene libraries. This analysis is complemented by the characterization of antibiotic resistance profiles of isolates obtained from urban aquatic environments. We detect communities capable of tolerating antibiotic concentrations up to 600 times higher than the clinical levels. Among the resistant organisms are included potentially pathogenic species, some of them classified as multiresistant. Our results extend the knowledge of the diversity of antibiotic resistance among environmental microorganisms and provide evidence that the diversity of drug-resistant bacteria in aquatic habitats can be influenced by pollution.
Identification of novel sources of host plant resistance to the soybean aphid biotypes

USDA-ARS?s Scientific Manuscript database

While soybean cultivars with resistance to the soybean aphid (Aphis glycines Matsumura) have been commercially released, the presence of virulent biotypes capable of overcoming plant resistance threatens the durability of host-plant resistance as a stable management tactic. Novel sources of host pla...
Selective removal of organic contaminants from sediments: A methodology for toxicity identification evaluations (TIEs)

USGS Publications Warehouse

Lebo, J.A.; Huckins, J.N.; Petty, J.D.; Ho, K.T.; Stern, E.A.

2000-01-01

Aqueous slurries of a test sediment spiked with dibenz[a,h]anthracene, 2,4,5,2′,4′,5′-hexachlorobiphenyl, p,p′-DDE, or phenanthrene were subjected to decontamination experimentation. The spiked sediments were agitated at elevated temperatures for at least 96 h in the presence of either of the two contaminant-absorbing media: clusters of polyethylene membrane or lipid-containing semipermeable membrane devices (SPMDs). The effects of treatment temperature and surface area of media on the removal of contaminants were explored. This work is part of a larger methodology for whole-sediment toxicity identification evaluation (TIE). A method is being sought that is capable of detoxifying sediments with respect to organic contaminants while leaving toxicity attributable to inorganic contaminants unaffected.
Two-dimensional resistivity investigation along West Fork Trinity River, Naval Air Station-Joint Reserve Base, Carswell Field, Fort Worth, Texas, October 2004

USGS Publications Warehouse

Shah, Sachin D.; Stanton, Gregory P.

2006-01-01

Naval Air Station-Joint Reserve Base Carswell Field (NAS-JRB) at Fort Worth, Tex., constitutes a government-owned, contractor-operated facility that has been in operation since 1942. Contaminants, primarily volatile organic compounds and metals, have entered the ground-water-flow system through leakage from waste-disposal sites and manufacturing processes. Ground water flows from west to east toward the West Fork Trinity River. During October 2004, the U.S. Geological Survey conducted a two-dimensional (2D) resistivity investigation at a site along the West Fork Trinity River at the eastern boundary of NAS-JRB to characterize the distribution of subsurface resistivity. Five 2D resistivity profiles were collected, which ranged from 500 to 750 feet long and extended to a depth of 25 feet. The Goodland Limestone and the underlying Walnut Formation form a confining unit that underlies the alluvial aquifer. The top of this confining unit is the top of bedrock at NAS-JRB. The bedrock confining unit is the zone of interest because of the potential for contaminated ground water to enter the West Fork Trinity River through saturated bedrock. The study involved a capacitively-coupled resistivity survey and inverse modeling to obtain true or actual resistivity from apparent resistivity. The apparent resistivity was processed using an inverse modeling software program. The results of this program were used to generate distributions (images) of actual resistivity referred to as inverted sections or profiles. The images along the five profiles show a wide range of resistivity values. The two profiles nearest the West Fork Trinity River generally showed less resistivity than the three other profiles.
Antioxidant Secondary Metabolites in Cereals: Potential Involvement in Resistance to Fusarium and Mycotoxin Accumulation

PubMed Central

Atanasova-Penichon, Vessela; Barreau, Christian; Richard-Forget, Florence

2016-01-01

Gibberella and Fusarium Ear Rot and Fusarium Head Blight are major diseases affecting European cereals. These diseases are mainly caused by fungi of the Fusarium genus, primarily Fusarium graminearum and Fusarium verticillioides. These Fusarium species pose a serious threat to food safety because of their ability to produce a wide range of mycotoxins, including type B trichothecenes and fumonisins. Many factors such as environmental, agronomic or genetic ones may contribute to high levels of accumulation of mycotoxins in the grain and there is an urgent need to implement efficient and sustainable management strategies to reduce mycotoxin contamination. Actually, fungicides are not fully efficient to control the mycotoxin risk. In addition, because of harmful effects on human health and environment, their use should be seriously restricted in the near future. To durably solve the problem of mycotoxin accumulation, the breeding of tolerant genotypes is one of the most promising strategies for cereals. A deeper understanding of the molecular mechanisms of plant resistance to both Fusarium and mycotoxin contamination will shed light on plant-pathogen interactions and provide relevant information for improving breeding programs. Resistance to Fusarium depends on the plant ability in preventing initial infection and containing the development of the toxigenic fungi while resistance to mycotoxin contamination is also related to the capacity of plant tissues in reducing mycotoxin accumulation. This capacity can result from two mechanisms: metabolic transformation of the toxin into less toxic compounds and inhibition of toxin biosynthesis. This last mechanism involves host metabolites able to interfere with mycotoxin biosynthesis. This review aims at gathering the latest scientific advances that support the contribution of grain antioxidant secondary metabolites to the mechanisms of plant resistance to Fusarium and mycotoxin accumulation. PMID:27148243
Using a multi-method approach based on soil radon deficit, resistivity, and induced polarization measurements to monitor non-aqueous phase liquid contamination in two study areas in Italy and India.

PubMed

Castelluccio, Mauro; Agrahari, Sudha; De Simone, Gabriele; Pompilj, Francesca; Lucchetti, Carlo; Sengupta, Debashish; Galli, Gianfranco; Friello, Pierluigi; Curatolo, Pierpaolo; Giorgi, Riccardo; Tuccimei, Paola

2018-05-01

Geochemical and geophysical surveys employing radon deficit, resistivity, and induced polarization (IP) measurements were undertaken on soil contaminated with non-aqueous phase liquids (NAPLs) in two different sites in India and in Italy. Radon deficit, validated through the comparison with average soil radon in reference unpolluted areas, shows the extension of contamination in the upper part of the unsaturated aquifers. In site 1 (Italy), the spill is not recent. A residual film of kerosene covers soil grains, inhibiting their chargeability and reducing electrical resistivity difference with background unpolluted areas. No correlation between the two parameters is observed. Soil volatile organic compounds (VOCs) concentration is not linked with radon deficit, supporting the old age of the spillage. NAPL pollution in sites 2a and 2b (India) is more recent and probably still active, as demonstrated by higher values of electrical resistivity. A good correlation with IP values suggests that NAPL is still distributed as droplets or as a continuous phase in the pores, strengthening the scenario of a fresh spill or leakage. Residual fraction of gasoline in the pore space of sites 2a and 2b is respectively 1.5 and 11.8 kg per cubic meter of terrain. This estimation is referred to the shallower portion of the unsaturated aquifer. Electrical resistivity is still very high indicating that the gasoline has not been strongly degraded yet. Temperature and soil water content influence differently radon deficit in the three areas, reducing soil radon concentration and partly masking the deficit in sites 2a and 2b.
Strength and wear resistance of a dental glass-ionomer cement with a novel nanofilled resin coating.

PubMed

Lohbauer, Ulrich; Krämer, Norbert; Siedschlag, Gustavo; Schubert, Edward W; Lauerer, Brigitte; Müller, Frank A; Petschelt, Anselm; Ebert, Johannes

2011-04-01

To evaluate the influence of different resin coating protocols on the fracture strength and wear resistance of a commercial glass-ionomer cement (GIC). A new restorative concept [Equia (GC Europe)] has been introduced as a system application consisting of a condensable GIC (Fuji IX GP Extra) and a novel nanofilled resin coating material (G-Coat Plus). Four-point fracture strength (FS, 2 x 2 x 25 mm, 14-day storage, distilled water, 37 degrees C) were produced and measured from three experimental protocols: no coating GIC (Group 1), GIC coating before water contamination (Group 2), GIC coating after water contamination (Group 3). The strength data were analyzed using Weibull statistics. Three-body wear resistance (Group 1 vs. Group 2) was measured after each 10,000 wear cycles up to a total of 200,000 cycles using the ACTA method. GIC microstructure and interfaces between GIC and coating materials were investigated under SEM and CLSM. The highest FS of 26.1 MPa and the most homogenous behavior (m = 7.7) has been observed in Group 2. The coated and uncoated GIC showed similar wear resistance until 90,000 cycles. After 200,000 wear cycles, the coated version showed significantly higher wear rate (ANOVA, P< 0.05). The coating protocol has been shown to determine the GIC fracture strength. Coating after water contamination and air drying is leading to surface crack formation thus significantly reducing the FS. The resin coating showed a proper sealing of GIC surface porosities and cracks. In terms of wear, the coating did not improve the wear resistance of the underlying cement as similar or higher wear rates have been measured for Group 1 versus Group 2.
Use of geoelectrical methods in groundwater pollution surveys in a coastal environment

NASA Astrophysics Data System (ADS)

Frohlich, Reinhard K.; Urish, Daniel W.; Fuller, James; O'Reilly, Mary

1994-08-01

The pollution of coastal aquifers by old landfills can contaminate valuable and scarce water resources in the freshwater lens utilized seasonably by overcrowded communities. The pollutants will ultimately flow into the sea where they may also cause a coastal water pollution problem. We have detected pollution in the freshwater lens from a sanitary landfill near Provincetown, Cape Cod, using the geoelectrical resistivity method. This survey included Schlumberger geoelectrical depth soundings and a horizontal geoelectrical profile using the Wenner configuration. The geoelectrical survey was conducted at a site along Highway 6 where it passes the coastal town of Provincetown and a sanitary landfill that has been in operation since 1954. The depth soundings suggest the characteristic decrease in resistivity vs. depth from the high resistivity of the unsaturated zone to the low resistivity of the saltwater saturated zone. The freshwater lens is clearly identified by the change in slope of the steeply dipping curve of resistivity versus electrode spacing. Interpretations made using a multilayer program, GEOMATE, resulted in layer resistivities between 460 and 95 ohm·m for the freshwater lens. A comparison with well water resistivities suggests that a layer resistivity of 230 ohm·m or lower is indicative of pollution in the freshwater lens. The results of the geoelectrical depth soundings were confirmed in the Wenner horizontal profile. Both measurements suggest that the pollutants do not spread evenly as one would expect for a homogeneous and isotropic medium. Instead, a preferred channel for the flow of the pollutants is observed along a path from the landfill toward the shoreline. The depth to the saltwater/freshwater interface or, more specifically, to the low resistivity-high resistivity interface appears to be shallow where the freshwater lens is polluted. This was confirmed by pore water well samples that were highly mineralized. The equilibrium postulated by the Ghyben-Herzberg relation appears to be disturbed in the area of aquifer pollution. This rise in the conductivity boundary is caused by the highly mineralized bottom of the contaminant plume that submerges into the saltwater saturated zone. In the area of high freshwater pollution the groundwater can be subdivided into three layers that show a decrease in resistivity with depth. The formation factor, F, defined as the ratio of bulk aquifer resistivity to pore water resistivity, shows unusually high values between 10 and 12. These high values are unexpected for an unconsolidated sand. Pollution residues are suspected to clog the pores and thus to increase the resistivity. It is possible that iron-oxidizing bacteria and the precipitation of dissolved iron or organic pollutants are the cause of the high values of F. If proven correct, these interesting possibilities could lead to future new applications of the geoelectrical resistivity method in contaminant hydroloy.
Use of geoelectrical methods in groundwater pollution surveys in a coastal environment

USGS Publications Warehouse

Frohlich, R.K.; Urish, D.W.; Fuller, J.; O'Reilly, M.

1994-01-01

The pollution of coastal aquifers by old landfills can contaminate valuable and scarce water resources in the freshwater lens utilized seasonably by overcrowded communities. The pollutants will ultimately flow into the sea where they may also cause a coastal water pollution problem. We have detected pollution in the freshwater lens from a sanitary landfill near Provincetown, Cape Cod, using the geoelectrical resistivity method. This survey included Schlumberger geoelectrical depth soundings and a horizontal geoelectrical profile using the Wenner configuration. The geoelectrical survey was conducted at a site along Highway 6 where it passes the coastal town of Provincetown and a sanitary landfill that has been in operation since 1954. The depth soundings suggest the characteristic decrease in resistivity vs. depth from the high resistivity of the unsaturated zone to the low resistivity of the saltwater saturated zone. The freshwater lens is clearly identified by the change in slope of the steeply dipping curve of resistivity versus electrode spacing. Interpretations made using a multilayer program, Geomate, resulted in layer resistivities between 460 and 95 ohm?m for the freshwater lens. A comparison with well water resistivities suggests that a layer resistivity of 230 ohm?m or lower is indicative of pollution in the freshwater lens. The results of the geoelectrical depth soundings were confirmed in the Wenner horizontal profile. Both measurements suggest that the pollutants do not spread evenly as one would expect for a homogeneous and isotropic medium. Instead, a preferred channel for the flow of the pollutants is observed along a path from the landfill toward the shoreline. The depth to the saltwater/freshwater interface or, more specifically, to the low resistivity-high resistivity interface appears to be shallow where the freshwater lens is polluted. This was confirmed by pore water well samples that were highly mineralized. The equilibrium postulated by the Ghyben-Herzberg relation appears to be disturbed in the area of aquifer pollution. This rise in the conductivity boundary is caused by the highly mineralized bottom of the contaminant plume that submerges into the saltwater saturated zone. In the area of high freshwater pollution the groundwater can be subdivided into three layers that show a decrease in resistivity with depth. The formation factor, F, defined as the ratio of bulk aquifer resistivity to pore water resistivity, shows unusually high values between 10 and 12. These high values are unexpected for an unconsolidated sand. Pollution residues are suspected to clog the pores and thus to increase the resistivity. It is possible that iron-oxidizing bacteria and the precipitation of dissolved iron or organic pollutants are the cause of the high values of F. If proven correct, these interesting possibilities could lead to future new applications of the geoelectrical resistivity method in contaminant hydroloy.
Bacterial Contamination of Adult House Flies (Musca domestica) and Sensitivity of these Bacteria to Various Antibiotics, Captured from Hamadan City, Iran.

PubMed

Nazari, Mansour; Mehrabi, Tahereh; Hosseini, Seyed Mostafa; Alikhani, Mohammad Yousef

2017-04-01

House flies ( Musca domestica ) have been known as a mechanical vector in spreading infectious diseases such as cholera, shigellosis, salmonellosis and skin infections. To investigate the bacterial contaminations of house flies and determine the resistance of these bacteria against various antibiotics. An analytical descriptive cross- sectional study was conducted. The study was performed from July to September 2015 in Hamadan University of Medical Sciences, Hamadan, Iran. A total number of 300 house flies were collected from four places, 75 flies from each place, including two educational hospitals belonging to Hamadan University of Medical Sciences, a fruit and vegetables center, and a livestock slaughter. The body surface of house flies was washed using the physiological sterile serum and the obtained solution was centrifuged at 2000 rpm for five minutes. The identification of bacteria was carried out using the phenotypic methods. The resistance of bacteria against various antibiotics was determined using the disk diffusion approach. Data were analysed by the employment of SPSS software package version 20.0. A total number of 394 bacterial strains were isolated from 275 house flies. The most prevalent type of bacteria was Bacillus spp which was detected in 31.1% of house flies. Moreover, Staphylococcus s pp. (22.9%), Escherichia coli (11.6%) were other prevalent species, whereas, Enterococcus s pp. was the least prevalent type of bacteria in the collected house flies. In terms of resistance to antibiotics, it was identified that bacteria extracted from house flies which were collected from hospital environments were more resistant to antibiotics compared with the resistance of bacteria extracted from house flies which were collected from non hospital environments. The maximum bacterial isolation was found in houseflies from hospital No.1 environment from around the accumulation of garbage. It is a well-known fact that house flies are a source of bacterial contamination and can act as a mechanical carrier and cause bacterial diseases. It can be postulated that house flies play a major role in spreading antibiotic resistant bacteria. However, the flies from hospital environments were more contaminated, mainly because the people referring to health center are normally ill and carrier of many pathogens. Further, hospital environments should be controlled using administrative procedures.
Using short vignettes to disentangle perceived capability from motivation: a test using walking and resistance training behaviors.

PubMed

Rhodes, Ryan E; Williams, David M; Mistry, Chetan D

2016-07-01

Self-efficacy is arguably the strongest correlate of physical activity, yet some researchers suggest this is because the construct confounds ability with motivation. We examine a more circumscribed construct, called perceived capability (PC), meant to measure ability but not motivation and propose that the construct will not be related to unskilled physical activities but may be linked to skilled behaviors. The purpose of this paper was to examine whether a PC construct can be stripped of motivation using a vignette approach in both walking and resistance training behaviors. Participants were a random sample of 248 university students, who were then randomly assigned to either answer resistance training or walking behavior questions. Both groups completed a PC measure and reasons for their answer before and after reading a vignette that clarified the phrasing of capability to a literal use of the term. PC was significantly (p < .01) higher post- compared to pre-vignette and the differences were greater (p < .01) for walking than for resistance training. PC had significantly (p < .01) smaller correlations with intention and self-reported behavior post-disambiguation, which resulted in a null relationship with walking but a small correlation with resistance training behavior. When PC was combined with intention to predict behavior, however, there was no significant (p > .05) difference in the amount of variance explained pre- to post-vignette. Thought listing showed that participants did not report capability barriers to walking and over half of the sample construed capability as motivation/other priorities pre-vignette. The findings support use of a vignette approach for researchers who wish to disentangle the assessment of PC from motivation while creating no overall loss in explained variance of physical activity.
Greenhouse study on the phytoremediation potential of vetiver grass, Chrysopogon zizanioides L., in arsenic-contaminated soils.

PubMed

Datta, Rupali; Quispe, Mario A; Sarkar, Dibyendu

2011-01-01

The purpose of this greenhouse study was to assess the capacity of vetiver grass to accumulate arsenic from pesticide-contaminated soils of varying physico-chemical properties. Results indicate that vetiver is capable of tolerating moderate levels of arsenic up to 225 mg/kg. Plant growth and arsenic removal efficiency was strongly influenced by soil properties. Arsenic removal was highest (10.6%) in Millhopper soil contaminated with 45 mg/kg arsenic, which decreased to 4.5 and 0.6% at 225 and 450 mg/kg, respectively. High biomass, widespread root system and environmental tolerance make this plant an attractive choice for the remediation of soils contaminated with moderate levels of arsenic.
Method for fabricating photovoltaic device having improved short wavelength photoresponse

DOEpatents

Catalano, Anthony W.

1989-07-04

Amorphous p-i-n silicon photovoltaic cells with improved short wavelength photoresponse are fabricated with reduced p-dopant contamination at the p/i interface. Residual p-dopants are removed by flushing the deposition chamber with a gaseous mixture capable of reacting with excess doping contaminants prior to the deposition of the i-layer and subsequent to the deposition of the p-layer.
Initial Field Deployment Results of Green PCB Removal from Sediment Systems (GPRSS)

NASA Technical Reports Server (NTRS)

Devor, Robert; Captain, James; Weis, Kyle; Maloney, Phillip; Booth, Greg; Quinn, Jacqueline

2014-01-01

Purpose of Study: (a) Develop/optimize technology capable of removing PCBs from contaminated sediments; (b) Develop design for functional GPRSS unit; (c) Produce and prove functionality of prototype units in a laboratory settings; (d) Produce fully-functional GPRSS units for testing at a demonstration site in Altavista, VA; and (e) Evaluate efficacy of GPRSS technology for the remediation of PCB-contaminated sediments.
The Prevalence of Antibiotic Resistance Genes in US Waterways and Their Relationship to Water Quality and Land Use Indicators

EPA Science Inventory

Antibiotic resistance genes (ARGs) in freshwaters are an emerging contaminant of concern. We used 1,747 water samples from the USEPA’s 2013-2014 National Rivers and Streams Assessment and digital-droplet polymerase chain reaction techniques to quantify the concentrations (t...
Resistance of fallow deer (dama dama) to chronic wasting disease under natural exposure in a heavily contaminated environment

USDA-ARS?s Scientific Manuscript database

Chronic wasting disease or CWD is a transmissible spongiform encephalopathy or prion disorder of cervid ruminants in several regions of the US and Canada. The prion disorders are characterized by misfolding of the host cellular prion protein into a relatively protease resistant and potentially neur...
Fate and transport of antimicrobials and antimicrobial resistance genes in soil and runoff following land application of swine slurry

USDA-ARS?s Scientific Manuscript database

Due to the use of antimicrobials in livestock production, residual antimicrobials and antimicrobial resistance genes (ARGs) could enter the environment following the land application of animal wastes and could further contaminate surface and groundwater. The objective of this study was to determine ...
Genotypic regulation of aflatoxin accumulation but not Aspergillus fungal growth upon post-harvest infection of peanut (Arachis hypogaea L.) seeds

USDA-ARS?s Scientific Manuscript database

Aflatoxin contamination is a major economic and food safety concern for the peanut industry that largely could be mitigated by genetic resistance. To screen peanut for aflatoxin resistance, Ten genotypes were infected with green fluorescent protein (GFP) - expression Aspergillus flavus strain. Per...
Validation of Fusarium head blight resistance QTL using the NC-Neuse / Bess doubled haploid population

USDA-ARS?s Scientific Manuscript database

Fusarium Head Blight (FHB) is one of the most damaging diseases of wheat. It lowers the grain yield and quality, and contaminates grain with the mycotoxin deoxynivalenol (DON). Genetic resistance is a critical control measure and breeding objective. Many studies have focused on the genetic basis of ...
Survey of candidate genes for maize resistance to infection by Aspergillus flavus and/or aflatoxin contamination

Treesearch

Leigh Hawkins; Marilyn Warburton; Juliet Tang; John Tomashek; Dafne Alves Oliveira; Oluwaseun Ogunola; J. Smith; W. Williams

2018-01-01

Many projects have identified candidate genes for resistance to aflatoxin accumulation or Aspergillus flavus infection and growth in maize using genetic mapping, genomics, transcriptomics and/or proteomics studies. However, only a small percentage of these candidates have been validated in field conditions, and their relative contribution to...

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