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Dissertations / Theses on the topic 'Microbial contamination'
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1
Lee, Cheuk-hung, and 李卓雄. "Microbial contamination of enteral feeds." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31245596.
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Anderton, A. "Microbial contamination of enternal feeds." Thesis, University of Glasgow, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377156.
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Zhang, Lin. "Microbial pathogen contamination in mouse gametes and embryos." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5671.
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Thesis (M.S.)--University of Missouri-Columbia, 2008."May 2008" The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Includes bibliographical references.
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Gerba, Charles P. "Microbial Contamination of Groundwater by Landfills: Risk Assessment." Arizona-Nevada Academy of Science, 1986. http://hdl.handle.net/10150/296388.
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From the Proceedings of the 1986 Meetings of the Arizona Section - American Water Resources Association, Hydrology Section - Arizona-Nevada Academy of Science and the Arizona Hydrological Society - April 19, 1986, Glendale Community College, Glendale, Arizona
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Horn, Owen. "Environmental Contamination by Metabolites of Microbial Degradation of Plasticizers." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92140.
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Earlier work with pure cultures has shown that the interaction of microbes with plasticizers leads to the formation ofmetabolites including 2-ethylhexanol and 2ethylhexanoic acid that resist further degradation. The same studies have shown that these compounds exhibit acute toxicity. This work has shown that the ability of soil micro-organisms to produce these metabolites from the degradation ofplasticizers is a general phenomenon. It was also found that the ability of soil organisms to degrade 2ethylhexanoic acid does not seem to be as common. Taken together, it would be expected that partial de gradation products of plasticizers should be observed in the environment. This was confirmed in a variety of environmental samples including sediments, surface waters, tap water, and fresh precipitation. Thus, even in a complex ecosystem, when plasticizers were degraded, the breakdown is not complete and significant amounts of2-ethylhexanoic acid and 2-ethylhexanol were observed. Since it is already weIl established that plasticizers are ubiquitous in the environment, it is expected that their recalcitrant metabolites will also be ubiquitous. This is a concem because, while the plasticizers do not exhibit acute toxicity, their metabolites do.Il a été démontré, lors d'études précédentes faites avec des cultures pures, que l'intéraction de microbes avec des plastifiants mène à la formation de certains métabolites résistant à une dégradation ultérieure, incluant le 2-éthylhexanol ainsi que l'acide 2éthylhexanoïque. Ces mêmes études ont aussi démontré que ces composés ont une toxicité aigue. Le présent ouvrage a démontré que l'habileté à produire ces métabolites à partir de la dégradation de plastifiants est un phénomène généralisé chez les microorganismes provenants des sols. Il a aussi été démontré que l 'habileté de ces microorganismes à dégrader l'acide 2-éthylhexanoïque ne semble pas être aussi répandue. À partir de ces observations, il semble que les produits de la dégradation partielle des plastifiants devraient être observables dans l'environnement. Ceci a été confirmé dans un éventail d'échantillons environnementaux incluant des sédiments, des eaux de surface, des eaux potables municipales et des précipitations. Donc même dans un écosystème complexe, lorsque les plastifiants sont dégradés, la décomposition n'est pas complète et des quantités notables d'acide 2-éthylhexanoïque et de 2-éthylhexanol sont observées. Puisqu'il a déjà été établi que les plastifiants sont omniprésents dans l'environnement, il est prévu que leurs métabolites récalcitrants y seront aussi omniprésents. Ceci présente un intérêt majeur puisque ces métabolites, contrairement aux plastifiants, possèdent une toxicité aigue fr
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Shepherd, Kim. "Health implications of microbial contamination of private water supplies." Thesis, University of Sunderland, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310618.
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Beattie, Tara Kate. "Microbial contamination of enteral tube feeds and feeding systems." Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417337.
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McEvoy, John Michael. "Microbial contamination on beef carcasses during slaughter and processing." Thesis, University of Ulster, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394622.
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Sudini, Hari Kishan Huettel Robin Norton. "Soil microbial community structure and aflatoxin contamination of peanuts." Auburn, Ala., 2009. http://hdl.handle.net/10415/1875.
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Clement, Mary. "The use of microbial community fingerprinting as a marker for tracking the source of water application to pathogen and groundwater source tracking /." Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/11132.
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Thesis (M.S.)--West Virginia University, 2010.Title from document title page. Document formatted into pages; contains ix, 49 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 47-49).
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Lupisella, Mark Lewis. "A theoretical microbial contamination model for a human Mars mission." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3366.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Biology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Barker, Christopher Stuart. "An investigation into microbial contamination of orthodontic instruments and materials." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555658.
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There is little information on the microbial contamination of orthodontic materials received from the manufacturer and if orthodontists pre-sterilise new products prior to use. These items may also become contaminated on the clinic or during laboratory construction. Recent regulations for decontamination in primary dental care (HTM 01- 05) have been introduced requiring a 60 day limit for storage time of sterilised instruments. The aims of this investigation were to determine whether components of fixed and removable orthodontic appliances are free from microbial contamination prior to clinical use; to establish the current practice in orthodontics with regard to pre- sterilisation of new products and to investigate possible re-contamination of sterilised dental instruments. A range of orthodontic materials "as received" from the manufacturer and "bench-top exposed" items were investigated. Bacterial contamination during the construction of removable appliances was evaluated from initial impression, through to delivery of the final appliance. Molecular microbiological techniques were used to obtain bacterial DGGE profiles and facilitate 16S rDNA identification. Questionnaires were distributed to consultant orthodontists to determine their current pre-sterilisation regimes for new orthodontic products. Twenty five dental mirrors were sterilised. These were tested (5 mirrors at each time point) for microbial contamination immediately after autoclaving and then at 31,60,90 and 124 days. Bacteria were isolated from "as received" bands, archwires and impression trays, but the level of contamination was low (0-3.65x102 cfu ml"). This was similar for clinic items. Much higher levels were found on removable appliances (0.97x102-1.52xl03 cfu mll ). There was no cross-contamination from patients to the laboratory; contamination occurred within the laboratory itself. The majority of consultant-led departments do not pre-sterilise materials from the manufacturer (88-97%). There was no bacterial growth from sterilised dental mirrors after 5 days of incubation at 37°C at any time period from 0 to 124 days post sterilisation. In conclusion, materials and appliances are not free from bacterial contamination prior to use in patients; improved cross infection control procedures are needed within the orthodontic laboratory. There is no current evidence for the 60-day storage of sterilised dental instruments as advised by the Department of Health.
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Decraene, Valerie. "Light-activated antimicrobial coatings for reducing microbial contamination of surfaces." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1446168/.
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Environmental surface contamination can contribute to cross-infection within hospitals by acting as a reservoir from which personnel and patients can soil their hands. It is important, therefore, to develop effective means of reducing the microbial load on such surfaces. One possible approach involves the use of photosensitisers, compounds which generate antimicrobial moieties (e.g. singlet oxygen), when irradiated with an appropriate light source. The overall aim of this study was to develop a coating containing photosensitisers that is able to kill microbes when irradiated with light generated by the type of lamp recommended for use in hospitals in the United Kingdom i.e. a 28 W General Electric fluorescent lamp. After comparing the absorption spectra of candidate compounds with the emission spectrum of the light source, the following photosensitisers were selected for study: Toluidine Blue O (TBO), Methylene Blue (MB), Methylene Violet (MV), Rose Bengal (RB), and Erythrosine B (ErB). The singlet oxygen ('02) producing ability of the selected compounds was then tested using the uric acid assay. All photosensitisers had comparable rates of lOj production but both ErB and RB became photobleached over time. Based on these results, TBO, MB and MV were selected for further study and lethal photosensitisation experiments were carried out using aqueous suspensions of Staphylococcus aureus, Escherichia coli, Candida albicans and Bacteriophage OX 174. All three photosensitisers produced significant kills against these four organisms but, while 2 hours of irradiation was sufficient for bacteria, longer (6 hour) irradiation was necessary to achieve substantial kills of the bacteriophage and yeast. These photosensitisers were then incorporated into cellulose acetate coatings, and the antimicrobial activity of these coatings was investigated. MV was found to be inactive when immobilized in the polymer and was therefore replaced by RB. The optimal coating of those tested contained a combination of 25 uM TBO and 25 uM RB. This coating was able to generate appreciable kills of a range of different microbes both when aliquoted on to the coating as a suspension and when sprayed on using a nebuliser. Significant kills were also achieved in the presence of horse serum and saliva and following prolonged irradiation of the coatings. A study of the environmental contamination present in a dental clinic was carried out using settle plates and revealed that both the number and variety of bacteria were significantly greater on days when clinics were held compared to days when there was no clinical activity. The most frequently encountered species were P. acnes, M. 2 2 luteus, and S. epidermidis and the mean total microbial load was 21.9 x 1(T cfu/m7h. The final stage of the project involved testing the activity of the TBO/RB coatings in this clinical setting. When compared to control (photosensitiser-free) coatings, the TBO/RB coatings achieved reduced counts on 12 out of the 15 days, with median reductions of 63.8 % and 81.8 % for aerobic and anaerobic bacteria respectively. Overall, these coatings show potential as a renewable, self-disinfecting surface and may have a range of applications in the hospital environment.
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Grodzki, Marco <1980>. "Evaluation of Microbial Contamination in Bivalve Mollusks: Epidemiology and Diagnosis." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4834/1/grodzki_marco_tesi.pdf.
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Shellfish are filter-feeding organisms that can accumulate many bacteria and viruses. Considering that depuration procedures are not effective in removal of certain microorganisms, shellfish-borne diseases are frequent in many parts of the world, and their control must rely primarily on investigation of prevalence of human pathogens in shellfish and water environment. However, the diffusion of enteric viruses and Vibrio bacteria is not known in many geographical areas, for example in Sardinia, Italy.
A survey aimed at investigating the prevalence of Norovirus (NoV), hepatitis A virus (HAV), V. parahaemolyticus, V. cholerae and V. vulnificus was carried out, analyzing both local and imported purified, non-purified and retail shellfish from North Italy and Sardinia. Shellfish from both areas were found contaminated by NoVs, HAV and Vibrio, including retail and purified animals. Molecular analysis evidenced different NoV genogroups and genotypes, including bovine NoVs, as well as pathogenic Vibrio strains, underlining the risk for shellfish consumers.
However, also other approaches are needed to control the diffusion of shellfish-borne diseases.
It was originally thought that enteric viruses are passively accumulated by shellfish. Recently, it was proven that NoVs bind to specific carbohydrate ligands in oysters, and various NoV strains are characterized by a different bioaccumulation pattern. To deepen the knowledge on this argument, a study was carried out, analyzing bioaccumulation of up to 8 different NoV strains in four different species of shellfish. Different bioaccumulation patterns were observed for each shellfish species and NoV strain used, potentially important in setting up effective shellfish purification protocols.
Finally, a novel study of evaluation of viral contamination in shellfish from the French Atlantic coast was carried out following the passage of Xynthia tempest over Western Europe which caused massive destruction. Different enteric viruses were found over a one month period, evidencing the potential of these events of contaminating shellfish.
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Grodzki, Marco <1980>. "Evaluation of Microbial Contamination in Bivalve Mollusks: Epidemiology and Diagnosis." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4834/.
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Shellfish are filter-feeding organisms that can accumulate many bacteria and viruses. Considering that depuration procedures are not effective in removal of certain microorganisms, shellfish-borne diseases are frequent in many parts of the world, and their control must rely primarily on investigation of prevalence of human pathogens in shellfish and water environment. However, the diffusion of enteric viruses and Vibrio bacteria is not known in many geographical areas, for example in Sardinia, Italy.
A survey aimed at investigating the prevalence of Norovirus (NoV), hepatitis A virus (HAV), V. parahaemolyticus, V. cholerae and V. vulnificus was carried out, analyzing both local and imported purified, non-purified and retail shellfish from North Italy and Sardinia. Shellfish from both areas were found contaminated by NoVs, HAV and Vibrio, including retail and purified animals. Molecular analysis evidenced different NoV genogroups and genotypes, including bovine NoVs, as well as pathogenic Vibrio strains, underlining the risk for shellfish consumers.
However, also other approaches are needed to control the diffusion of shellfish-borne diseases.
It was originally thought that enteric viruses are passively accumulated by shellfish. Recently, it was proven that NoVs bind to specific carbohydrate ligands in oysters, and various NoV strains are characterized by a different bioaccumulation pattern. To deepen the knowledge on this argument, a study was carried out, analyzing bioaccumulation of up to 8 different NoV strains in four different species of shellfish. Different bioaccumulation patterns were observed for each shellfish species and NoV strain used, potentially important in setting up effective shellfish purification protocols.
Finally, a novel study of evaluation of viral contamination in shellfish from the French Atlantic coast was carried out following the passage of Xynthia tempest over Western Europe which caused massive destruction. Different enteric viruses were found over a one month period, evidencing the potential of these events of contaminating shellfish.
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Trickett, Michelle D. "Investigation of environmental microorganisms associated with the intrinsic microbial contamination of an alcohol-free mouthwash." Huntington, WV : [Marshall University Libraries], 2007. http://www.marshall.edu/etd/descript.asp?ref=810.
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Harrison, Adrian Briscoe. "Hydrocarbon pollution of soil : effects on microbial populations and biomediation methods." Thesis, University of York, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362025.
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Fall, Claudia. "Microbial Contamination Assessment with SWAT in a Tile-Drained Rural Watershed." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20057.
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Microbial contamination of drinking water poses an important health risk which causes severe illnesses and epidemics. In order to improve surface and drinking water quality, the understanding of fecal pathogen contamination processes including their prevention and control needs to be enhanced. The watershed model soil water assessment tool (SWAT) is commonly used to simulate the complex hydrological, meteorological, erosion, land management and pollution processes within river basins. In recent years, it has been increasingly applied to simulate microbial contamination transport at the watershed scale. SWAT is used in this study to simulate Escherichia coli (E.coli) and fecal coliform densities for the agriculturally dominated Payne River Basin in Ontario, Canada. Unprecedented extensive monitoring data that consist of 30 years of daily hydrological data and 5 years of bi-weekly nutrient data have been used to calibrate and validate the presented model here. The calibration and validation of the streamflow and nutrients indicate that the model represent these processes well. The model performs well for periods of lower E. coli and fecal coliform loadings. On the other hand, frequency and magnitude of higher microbial loads are not always accurately represented by the model.
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TemÃteo, Guilherme de Alencar. "Analysis of microbial contamination of device acrylic manufactured in dental laboratories." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12052.
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Universidade Federal do CearÃA possÃvel presenÃa de microorganismos potencialmente patogÃnicos em prÃteses dentÃrias recÃm-chegadas dos laboratÃrios protÃticos deve ser considerada. Este estudo avaliou o nÃvel de contaminaÃÃo bacteriana e fÃngica de espÃcimes de resina acrÃlica confeccionados em 14 laboratÃrios de prÃtese dentÃria, inscritos no Conselho Regional de Odontologia do CearÃ, na cidade de Fortaleza. Cada laboratÃrio foi solicitado a confeccionar 10 espÃcimes de resina acrÃlica, a partir de modelos padronizados de silicona de adiÃÃo estÃreis, desconhecendo os objetivos da pesquisa. Os espÃcimes recebidos dos laboratÃrios foram colocados em tubos individuais contendo BHI caldo e incubados a 37ÂC por 48 horas e, em seguida, removidos, lavados, colocados em soluÃÃo salina estÃril e agitados para desprendimento microbiano. A suspensÃo obtida foi diluÃda em 1:100, 1:1000 e semeada em placas com Ãgar Sangue, Sabouraud Dextrose Ãgar e HICrome UTI ÃgarÂ, para incubaÃÃo por 48 horas a 37ÂC. Foi obtido o nÃmero de unidades formadoras de colÃnias (UFC) bacterianas e fÃngicas viÃveis, alÃm da identificaÃÃo e quantificaÃÃo de algumas espÃcies de bactÃrias, comparando-se os laboratÃrios por meio dos testes de Kruskall-Wallis e Dunn (α=0.05). Houve contaminaÃÃo advinda de todos os laboratÃrios analizados, com uma contagem de UFC mÃdia de 101438 de bactÃrias e 71047 de fungos. Pseudomonas spp foi o microorganismo a mais prevalente identificado (p<0,05). Foi concluido que existe risco de contaminaÃÃo por bactÃrias potencialmente patogÃnicas e fungos em dispositivos protÃticos recÃm chegados dos laboratÃrios.
The possible presence of potentially pathogenic microorganisms in denture newly arrived from prosthetic laboratories should be considered. This study evaluated the level of bacterial and fungal contamination of specimens of acrylic resin made in 14 dental laboratories registered with the Regional Council of Dentistry of CearÃ, Fortaleza. Each laboratory was asked to fabricate 10 specimens of acrylic resin, from standard models of sterile silicone addition, unaware of the research objectives. Specimens received from laboratories were placed in individual tubes containing BHI broth, incubated at 37ÂC for 48 hours and then removed, washed and placed in sterile saline and stirred for microbial detachment. The suspension obtained was diluted (1:100, 1:1000) and plated on blood agar plates, and Sabouraud Dextrose Agar and Agar HiCrome ICU by incubation for 48 hours at 37ÂC. The number of colony forming units (CFU) bacterial and fungal viable was obtained, besides the identification and quantification of some species of bacteria, comparing the laboratory by means of the Kruskal-Wallis and Dunn (α = 0.05) tests. There was contamination originating from all laboratories analyzed, with a mean CFU counts of 101438 bacteria and 71047 fungi. Pseudomonas spp was the most prevalent microorganism identified (p < 0.05). It was concluded that there is a risk of contamination with potentially pathogenic bacteria and fungi in prosthetic devices newly arrived from dental laboratories.
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Lal, Sham. "Investigating contamination of dental-unit waterline systems and microbial biofilm ecology." Thesis, University of Central Lancashire, 2016. http://clok.uclan.ac.uk/16659/.
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Introduction: Biofilms within dental-unit waterlines (DUWLs) are acknowledged sources of contamination in the dental clinical environment and affect the quality of clinical treatment water. As a standard for reducing exposure to potentially harmful microorganisms, the Department of Health (DoH), UK suggests that water discharged from DUWL should contain 100 to 200 CFU/mL. However, local audits suggest that the quality of clinical treatment water often fails to meet the standards required. The aim: The aim was to be able to readily identify waterlines with higher levels of contamination via validation of a rapid existing “in-office” test and subsequently understand biofilm ecology. Materials and Methods: Water samples from 31 DUWLs in general dental practices were taken during the working day and cultured using the PetrifilmTM AC plate test as per manufacturer’s instructions and for extended incubation periods under laboratory conditions. The samples were also cultured using the laboratory based benchmark R2A agar. Further culture methods were employed for investigating spread of human pathogens with aerosolization and splatter of DUWL water; retraction valve failure; waterborne biofilm ecology and environment within a simulated laboratory DUWL (sDUWL) and whether amoebae were harboring nosocomial bacteria. Results: The bacterial concentration of the water samples cultured on R2A agar varied significantly (1 × 101 to 4.3 × 106); in surgeries (48%) which met DoH standards and those that failed (52%). A retest of water from surgeries which delivered safe and contaminated water revealed that approximately 55% of practices met the recommended threshold values whilst around 45% failed. The PetrifilmTM AC Plate method gave variable sensitivity values on different occasions with 100% specificity. Only the nosocomial clinical isolate of Serratia marcescens was recovered from one clinical water sample. The opportunistic yeast, Candida parapsilosis from 1 sample indicated possible retraction valve failure. The in-vitro sDUWL output water demonstrated a fully established biofilm community by day 2 consisting of bacteria, a fungus (Cladosporium cladosporioides), and one amoeba (Vermamoeba vermiformis) as the main organisms. When tested under laboratory culture conditions, V. vermiformis, appeared to feed on S. marcescens isolated from clinical water. Electron microscopy confirmed bacterial adherence characteristics for biofilm formation, and altered pattern of cell division in one Gram positive isolate from the in-vitro sDUWL. Despite the detection of a Legionella species, no metabolically active opportunistic human pathogens were observed within V. vermiformis in the sDUWL biofilm. Conclusions: This study demonstrates the importance of regular monitoring of DUWL water because even clean DUWLs can quickly become contaminated. One aim of this study was to find an in-office testing method for dental needs but it appears that improving the sensitivity of in-office tests is a challenge that needs addressing in the first instance. A more positive outcome was that, on the whole, clinical output water was not harbouring opportunistic human pathogens at the time of testing and that clinical surfaces were clean. Also when dental units are used there was no evidence that contaminants were being drawn back into the DUWLs. Overall, achieving a low level of microbial contamination consistently in water to 100 - 200 CFU/mL appeared to be difficult. In the short-term, if water could be tested more often this would help to understand the related challenges associated with conforming to national standards of delivering clean treatment water. The laboratory sDUWL model showed defective cell division and altered phenotype of specific bacterial species, and that V. vermiformis appeared unlikely to be harboring the late coloniser L. pneumophila, as it was out-with the size-range of bacteria, amoebae choose to feed upon. As the laboratory sDUWL model closely mimicked the heterogeneous biofilm development including the type of main microorganisms as those of the clinical DUWL it can be used to accurately accesses commercial biocides in the control of the biofilm independently as literature continues to question the efficacy of commercial disinfections in waterline cleansing protocols that fail to meet the required standards.
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Allevi, Richard Paul. "Quantifying Potential Sources of Microbial Contamination in Household Drinking Water Samples." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/42011.
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In Virginia, over one million households rely on private water supplies (e.g. well, spring, cistern). Previous literature acknowledges bacterial contamination in private water supplies as a significant public health concern in the United States. The present study tested private wells and springs in 20 Virginia counties for total coliforms (TC) and E. coli (EC) along with a suite of chemical contaminants. Sample collection was organized by the Virginia Household Water Quality Program (VAHWQP), a Virginia Cooperative Extension effort managed by faculty in the Biological Systems Engineering Department. Microbial and chemical source tracking were used to identify possible sources of contamination. A logistic regression was employed to investigate potential correlations between TC contamination and chemical parameters (e.g. NO3-, turbidity) as well as homeowner provided survey data describing system characteristics and perceived water quality.
TC and EC contamination were quantified via the Colilert (www.idexx.com) defined substrate method for most probable number (MPN) of EC and TC per 100 mL of water. Of the 538 samples collected, 41% (n=221) were positive for TC and 10% (n=53) for EC. Chemical parameters were not statistically predictive of microbial contamination. Well depth, water treatment, and farm location proximate to the water supply were factors in a regression model that predicted presence/absence of TC with 74% accuracy. Microbial and chemical source tracking techniques (Polymerase Chain Reaction (PCR) and fluorometry, respectively) identified 4 of 26 samples as likely contaminated with human wastewater. Application of these source-tracking analyses on a larger scale will prove useful in defining remediation strategies.Master of Science
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Lambropoulou, Kyriaki A. "The effects of varying extrinsic parameters and specific pretreatments in whole fish and prepared fish fillets." Thesis, University of Lincoln, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342433.
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Geary, Phillip M., University of Western Sydney, of Science Technology and Environment College, and of Science Food and Horticulture School. "On-site system effluent source tracking using geochemical and microbial tracers in a coastal catchment." THESIS_CSTE_SFH_Geary_P.xml, 2004. http://handle.uws.edu.au:8081/1959.7/566.
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The principal aims of this thesis were to examine whether there were hydraulic links between individual on-site wastewater systems in sandy soils at Salt Ash and the Tilgerry Creek estuary near Port Stephens, New South Wales, and whether the chemical and microbiological contaminants from on-site systems could reach surface and groundwaters, and possibly lead to impacts on estuarine oyster growing waters. The research outcomes are contained within the thesis and in four refereed papers presented at conferences, and which have been subsequently published, or are in press. Copies of each of these papers are contained within the thesis Appendices. The presence of faecal contamination from domestic systems in the estuary, and surface drains in particular, has been confirmed by work contained in this thesis. The potential level of risk to human health from the consumption of contaminated oysters is, however, regarded as very low, although an assessment of health risk using established microbial assessment models has not been undertakenDoctor of Philosophy (PhD)
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Hussain, Shayne. "Evaluation of microbial extracts for contamination control in plant tissue culture systems." Thesis, University of Plymouth, 1991. http://hdl.handle.net/10026.1/2716.
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Culture filtrates of 13 microbial antagonists exhibited in vitro growth inhibition of a range of test contaminations of herbaceous and woody plant tissue culture systems. Filtrates produced by Bacillus subtilis and Trichoderma viride isolates displayed the greatest broad- range inhibitory activity. Microscopic analysis of antagonized fungal mycelia revealed altered hyphal morphology. Maximum filtrate inhibitory activity was produced when selected antagonists were cultured within a pH range of 5-7 and a temperature range of 20-35°C. Filtrates were thermo-stable at 70°C and could be stored for up to 4 weeks with only a minimal reduction in their inhibitory activity. Bulk-volume production of inhibitory filtrates of a T. viride isolate was achieved by optimization of fermentation pH, temperature, and aeration conditions. Plant culture species displayed different responses when grown on media incorporated with microbial filtrates. Microscopy studies at the cellular level revealed reduced cell densities and cellular distortion in plant tissues treated with phytotoxic doses of microbial filtrates. Non-phytotoxic doses of filtrated produced by the B. subtilis and T. viride isolates produced a reduction in the density of opportunistic contaminations in herbaceous plant tissue cultures when applied as prophylactic treatments. Microbial filtrates proved totally ineffective when employed as post-infection sterilants in contaminated plant cultures. The efficacy of selected microbial filtrates was not comparable to that of conventional antibiotics when assessed for their ability to control contamination levels in herbaceous and woody plant culture systems. Further purification of microbial filtrates for enhanced inhibitory activity is discussed along with the possibility of co-cultivation of micro-organisms with plant tissue cultures as a means of biocontrol of phytopathogens.
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Malkin, Christopher James Roger. "Potential use of ozone to reduce microbial contamination of minimally processed produce." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443994.
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Wolfe, Andrea N. C. (Andrea Nancy Cornell) 1977. "Microbial contamination in the Kathmandu Valley drinking water supply and Bagmati River." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9016.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.Includes bibliographical references (leaves 70-71).
The purpose of this investigation was to determine and describe the microbial drinking water quality problems in the Kathmandu Valley. Microbial testing for total coliform, E.coli, and H2S producing bacteria was performed in January 2000 on drinking water sources, treatment plants, distribution points, and consumption points. Existing studies of the water quality problems in Kathmandu were also analyzed and comparisons of both data sets characterized seasonal, treatment plant, and city sector variations in the drinking water quality. Results showed that 50% of well sources were microbially contaminated and surface water sources were contaminated in 100% of samples. No samples from drinking water treatment plant outflow were microbially contaminated; however almost 80% of samples collected at distribution points had microbial contamination and 60% were contaminated with E.coli. Drinking water quality varied little throughout the city but had significant seasonal variation. Microbial contamination in the Bagmati River was also studied and extremely high levels of microbial pollution were found. Pollution concentrations in the river are increasing over time as the population of the Valley grows rapidly. Wastewater treatment is virtually non-existent and most of the wastewater generated in the City flows untreated into the river. This causes increased pollution concentrations as the Bagmati flows downstream from the sparsely populated headwaters through the heavily urbanized Kathmandu City. Despite the high microbial pollution levels, many people use the river for washing, scavenging, and religious purposes. These activities, as well as contaminated drinking water, threaten the health of the population. Recommendations for drinking and surface water quality improvements can be divided into three areas: regulatory, policy, and technical. Laws and regulations are needed that specify those individuals and agencies who are responsible for water quality and monitoring, set water quality standards, and assign penalties to polluters. Drinking water policy must focus on fully funding programs and educating the public. Technical recommendations include separating drinking water and wastewater pipelines to eliminate leakage between the two and community or household-scale systems for both drinking water and wastewater treatment.
Andrea N.C. Wolfe.
M.Eng.
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Haricombe, Erin. "Transport and fate of chemical and microbial tracers at University of Western Cape (UWC) campus site, Cape Flats aquifer of South Africa." University of the Western Cape, 2016. http://hdl.handle.net/11394/5233.
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>Magister Scientiae - MScExtreme weather events in combination with geographical changes in groundwater utilization, groundwater availability, aquifer recharge, and ultimately changes in the quality of water resources, are expected in the future. As a consequence of changing weather patterns and urbanization the demand for groundwater is likely to increase in certain areas. We know that most waterborne pathogenic health epidemics are associated with contamination of farm water and wastewater. There is however limited understanding of the nature and extent of chemical, physical and biological processes that control the fate and transport of the microorganisms in primary and secondary aquifers. In this thesis, transport results are reported, where E. coli and PDR1 were selected as the biological tracers transported through a primary aquifer at the University of the Western Cape. In conjunction with the microbes salt and Rhodamine (chemical tracers) were injected to compare their fate and transport mechanism in the primary aquifer medium. A series of controlled Darcy experiments under laboratory and field conditions were conducted. Each provided a different data and information. The results from laboratory studies were used to improve design of the field studies. In both cases, the data collected provided information on fate and transport of microbes in groundwater. The field design phase of the experiment was an up-scaling of the laboratory phase of this project. The amount of chemical tracers injected into the aquifer was increased in proportion to the size of the research site. Tracer tests using chemical and microbial tracers were conducted simultaneously. Results of laboratory tests demonstrate a 5 times slower transport of microbes, compared to tests with salts during the laboratory phase. The salts at field scale show a breakthrough occurring after 2 days whereas the microbes –did not break through during the 28 days of the observation period. A new borehole was drilled closer to the pumping borehole to eliminate distance or travel time, but this had no effect on field results for the microbes.
National Research Foundation
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Randima, Livhuwani Priscilla. "Rhizosphere microbial diversity in PAH's contaminated and uncontaminated soil." Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-11302009-195201/.
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Kirs, Marek. "Quantitative analyses of F+ specific RNA coliphages /." View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3206253.
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Dillon, Vivian Maureen. "Sulphite tolerance of yeasts from comminuted lamb products." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383909.
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Lane, Marshalle. "Dispersive liquid-liquid micro-extraction coupled with gas chromatography for the detection of trihalomethanes in different water sources in the Western Cape, South Africa." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2852.
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Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2018.Trihalomethanes (THMs) are a group of four compounds that are formed, along with other disinfected by-products. This happens when chloride or other disinfectants are used to control microbial contamination in drinking water, which then reacts with natural organic or inorganic substances in water. Trihalomethanes are better known by their common names such as chloroform, bromodichloromethane, chlorodibromomethane and bromoform. These four compounds are known to be classified as cancer group B carcinogens (shown to cause cancer in laboratory animals). Trihalomethane levels tend to increase with pH, temperature, time and the level of “precursors" present. Precursors are known to be organic substances which react with chloride to form THMs. One significant way of reducing the amount of THMs in water is to eliminate or reduce chlorination before filtrations and reduce precursors. There are guideline limits for THMs in the SANS 241:2015 document, but they are not continuously monitored and their levels in natural water are not known. The aim of this study is to develop a rapid, fast and reliable liquid-liquid microextraction technique, to determine the presence of THMs in natural water sources. This study particularly focuses on different water sources e.g. river, underground, borehole and chlorinated water. Chlorinated water is the water that has been presumably treated for bacteria and fungus growth. The results that were obtained for chlorinated water are as follow, 10.120 μg/L − 11.654 μg/L for chloroform, 2.214 μg/L - 2.666 μg/L for bromodichloromethane, 0.819 μg/L − 0.895 μg/L chlorodibromomethane and 0.103 μg/L - 0.135 μg/L for bromoform from validation data. All these THMs concentrations have been found to be below the SANS 241:2015 limits. Natural water shows a very high affinity for chloroform. This is what is expected under normal conditions as chloroform is the most abundant THM of all THMs present in natural water. The liquid-liquid microextraction technique that was optimized and used for the determination of THMs in this study is a rapid, simple and inexpensive technique that provides low limits of detection (LOD) e.g. 0.1999 μg/L chlorodibromomethane and 0.2056 μg/L bromoform and wide dynamic range (LOQ) of 0.6664 μg/L chlorodibromomethane and 0.6854 μg/L bromoform for the determination of THMs.
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Blair, Tina Caroline. "Some factors influencing the survival of microbial contamination in solid oral dosage forms." Thesis, King's College London (University of London), 1989. https://kclpure.kcl.ac.uk/portal/en/theses/some-factors-influencing-the-survival-of-microbial-contamination-in-solid-oral-dosage-forms(25307998-751d-4cb1-ae1b-49bf680e395c).html.
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Smith, Meghan Kathleen 1976. "Microbial contamination and removal from drinking water in the Terai region of Nepal." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84288.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.Vita.
Includes bibliographical references (leaves 81-85).
by Meghan Kathleen Smith.
M.Eng.
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Troup, Daniel James, and Daniel James Troup. "Impact of Passive Air Treatment on Microbial Contamination in a Controlled Chamber Environment." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/625694.
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Microbial pathogens commonly transmitted through the aerosol route to surfaces, equipment, and hands in the clinical setting leads to costly and life threatening hospital-acquired infections (HAIs). Even with improved hand hygiene and surface disinfection, HAIs continue to persist in healthcare environments, warranting consideration of novel interventions to reduce the transmission risk of HAIs. This study quantitated the efficacy of ion generating passive air treatment (PAT) against viruses (MS2), bacteria (Escherichia coli), and bacterial spores (Bacillus thuringiensis) in a controlled environmental setting.
Microorganisms were seeded into a 2.72 m3 chamber using a positive pressure nebulizing device to generate aerosolized droplets. The PAT unit was then turned on and seeded organisms were collected at various time points using impingers to concentrate the organisms into sterile aqueous solution. The microorganisms were enumerated using approved standard protocols developed in the Environment, Exposure Science, and Risk Assessment Center's laboratory at The University of Arizona.
Three experiments were conducted to challenge the PAT unit. Experiment one evaluated the efficacy of the PAT unit over a single 10-minute period on microbial inactivation from the airborne environment following a single seeding; additionally, experiment one aimed to determine the efficacy of the PAT unit against viruses, bacteria, and bacterial spores on environmental surfaces; experiment two evaluated the efficacy of the PAT unit running continuously over a period of 6 hours following a single seeding; and experiment three evaluated the efficacy of the PAT unit running two continuously over a period of 5.25 hours following two seeding events. Bacterial spores from pre- and post-treatment with the PAT unit were collected and analyzed by scanning electron microscopy to assess structural differences.
After a single seeding and 10 minutes of continuous treatment of the PAT unit, normalized average microbial log10 reductions of post-treatment compared to pre-treatment air concentrations were 1.67, 0.59, and 1.04 for MS2, B. thuringiensis spores, and E. coli, respectively. Differences in average log10 reductions between the control unit and the PAT unit were statistically significant for MS2 (p=0.009) and B. thuringiensis (p=0.0455), but not for E. coli (p=0.0565). The geometric mean log10 surface concentrations of MS2, B. thuringiensis, and E. coli after a single seeding and 10 minutes of continuous treatment of the PAT unit were 7.30 PFU/100 cm2, 5.90 CFU/100 cm2, and 2.74 CFU/100 cm2, respectively, compared to exposure of the control unit, 8.59 PFU/100 cm2, 6.03 CFU/100 cm2, and 4.96 CFU/100 cm2, respectively. There was a statistically significant difference between the mean log10 surface concentrations following 10 minutes of treatment with the control unit compared to the PAT unit for E. coli (p=0.002), but not for MS2 (p=0.3358) or B. thuringiensis (p=0.0866).
After a single seeding and 6-hours of continuous treatment of the PAT unit, normalized average microbial log10 reductions of MS2 and B. thuringiensis were 1.43 and 1.32, respectively. The difference in average log10 reduction of all post-treatment samples between the control unit and the PAT unit was statistically significant for B. thuringiensis (p=0.0008) but not for MS2 (p=0.2568).
After two seedings and 5.25 hours of continuous treatment of the PAT unit, normalized average microbial log10 reductions of MS2 and B. thuringiensis were 1.59 and 1.26, respectively. There was a statistically significant difference in the average log10 reductions between the control unit and the PAT unit for MS2 (p=0.002) and B. thuringiensis (p=0.0003).
Scanning electron microscopy analysis identified visual modification to B. thuringiensis spores following treatment with the PAT unit. In this study, the tested ion generating PAT unit was effectively able to reduce airborne microbial concentrations between 1-2 log10 in a controlled chamber environment within 10 minutes and up to 6 hours of treatment. The implications of this study suggest that ion producing PAT systems may represent a beneficial supplement to cleaning and disinfection practices in the reduction of pathogen contamination from the airborne and fomite-airborne routes.
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Jeanbille, Mathilde. "Réponse des consortia microbiens benthiques à une contamination chronique aux hydrocarbures." Thesis, Pau, 2015. http://www.theses.fr/2015PAUU3043/document.
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Les communautés microbiennes procèdent au recyclage des nutriments et à la degradation de la matière organique, et sont ainsi essentielles aux cycles biogéochimiques dans le sédiment et plus largement dans les océans. La contamination chronique aux hydrocarbures représente près de 80% des déversements totaux dans les océans. Toutefois, en comparaison des marées noires, son impact sur les communautés microbiennes est encore mal compris. Dans cette étude, nous avons d’abord utilisé une approche de type méta-analyse pour élucider l’effet global de la contamination aux hydrocarbures dans différents habitats. La réponse des communautés bactériennes à la contamination s’est révélée être dépendante du type d’habitat, les sols étant plus impactés que d’autres habitats, comme par exemple les sédiments marins. Nous nous sommes ensuite intéressés aux communautés microbiennes des trois domaines du vivant de sédiments côtiers provenant des côtes méditerranéennes et atlantiques. La contamination chronique n’influençait que marginallement les communautés benthiques, et la diversité alpha n’était pas réduite dans les sédiments contaminés. Cedendant, la comparaison des réseaux de co-occurrence des échantillons contaminés et non-contaminés a montré que le réseau des communautés contaminées présentait une topologie différente, indiquant une vulnérabilité plus importante à d’éventuelles perturbations environnementales. Des indicateurs potentiels de la contamination identifiés avec la méta-analyse ont été ciblés pour étudier l’impact de la contamination chronique aux hydrocarbures sur les services écologiques qu’ils assurent (i.e. la dégradation de la matière organique et des hydrocarbures) en utillisant la technique de Micro-FISHWithin the sediment, microbial communities play a pivotal role by driving essential processes such as nutrient cycling and organic matter degradation. Chronic hydrocarbons contamination represents almost 80% of the total input in the oceans. However, as compared to oil spills, its impact on microbial communities remains poorly understood. In this study, we first used a meta-analysis approach to decipher the global effect of hydrocarbons contamination in different habitats. Bacterial community response to the contamination was found to be dependant of the habitat studied, with soils being more impacted than other habitats, like marine sediments. Because bacteria are in interactions with other important members of microbial communities such as Archaea and Eukaryotes, we focused on microbial communities from the three domains of life in coastal marine sediments from the Mediterrranean and the French Atlantic coasts. Independently of the domains of life, chronic hydrocarbons contamination appeared to be a poor driver of communities structuration, and alpha diversity was not reduced in contaminated sediments. However, the comparison of co-occurences networks of contaminated and non-contaminated samples showed that the network from the contaminated samples exhibited a different topology, which suggests a higher vulnerability to eventual environmental perturbations. Potential indicators species identified using the meta-analysis approach were targeted to study the impact of chronic contamination on the ecological services they provide (i.e. organic matter and hydrocarbons degradation) using the Micro-FISH method
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Lam, Fung Robert. "Extent and predictors of microbial hand contamination in a tertiary care ophthalmic outpatient practice." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/b39724153.
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Lam, Fung Robert, and 林峯. "Extent and predictors of microbial hand contamination in a tertiary care ophthalmic outpatient practice." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B39724153.
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Le, Nhu Da, Thi Xuan Binh Phung, and Thi Phuong Quynh Le. "Microbial contamination in the surface water in the Ba Vi National Park, Ha Noi." Technische Universität Dresden, 2018. https://tud.qucosa.de/id/qucosa%3A33125.
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Ba Vi National Park, one of 28 Vietnam National parks, is currently preserved and exploited for a variety of purposes, including the preservation of intact natural forest ecosystems and genetic resources of rare plants and animals. This paper presents the monitoring results of microbial contamination in surface water environment of the Ba Vi National Park (Ha Noi) in the period 2013-2014 and 2018. The results showed that total coliform (TC) density varied from 23 to 11,000 MPN/100ml in bimonthly observation in 2013-2014 which was lower than that one of sampling campaign in 2018, from 900 MPN/100ml to 8,100 MPN/ml. Fecal coliform (FC) densities vaired from 0 to 110 MPN/100ml in 2013 -2014 were lower than that in 2018, from 0 MPN/100ml to 600 MPN/100ml. At several observation time, both TC and FC were higher than the allowable values of the Vietnam national technical regulation QCVN 08-MT: 2015/BTNMT column A1 for surface water quality. The exceeded values of TC and FC than the allowable values and the increase trend from the 2013 to 2018 periods indicated the potential risks to the public health in this region when people use water for domestic and agricultural purposes. Our results provide dataset for environmental management in the Ba Vi National Park in order to protect the eco-environment in parallel with economical-social development.Vườn Quốc gia Ba Vì, một trong 28 vườn quốc gia của Việt Nam hiện đang được bảo tồn và khai thác cho nhiều mục đích, trong đó có bảo tồn nguyên vẹn các hệ sinh thái rừng tự nhiên, các nguồn gen động, thực vật quý hiếm, các đặc sản rừng và các di tích lịch sử, cảnh quan tự nhiên trong vùng. Bài báo trình bày kết quả quan trắc, đánh giá mức độ ô nhiễm vi sinh vật trong môi trường nước mặt tại Vườn Quốc Gia Ba Vì, Hà Nội giai đoạn 2013-2014 và 2018. Kết quả cho thấy mật độ coliform tổng số (TC) biến đổi trong khoảng từ 23 – 11.000 MPN/100ml trong các đợt quan trắc định kỳ 2 tháng/lần trong hai năm 2013 - 2014 và trong khoảng từ 900 – 8.100 MPN/100ml trong một đợt quan trắc năm 2018. Mật độ fecal coliform (FC) biến đổi trong khoảng từ 0 - 110 MPN/100ml năm 2013 -2014 và từ 0 - 600 MPN/100ml vào năm 2018. Vào một số thời điểm quan trắc, mật độ FC và TC vượt giá trị cho phép của quy chuẩn kỹ thuật Quốc Gia QCVN 08-MT:2015/BTNMT cột A1 về chất lượng nước mặt. Các giá trị TC và FC vượt quá giá trị cho phép và xu hướng gia tăng TC và FC từ 2013 -2018 cho thấy nguy cơ tiềm tàng khi người dân sử dụng nguồn nước này cho các mục đích sinh hoạt và nông nghiệp. Như vậy, kết quả của nghiên cứu này nhấn mạnh nhu cầu giám sát thường xuyên chất lượng nước và cần thực hiện các giải pháp hiệu quả để xử lý và quản lý nguồn gây ô nhiễm trong khu vực nhằm bảo vệ môi trường sinh thái song song với phát triển kinh tế - xã hội của khu vực.
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Tran, Dao. "Identifying risks associated with organic soil amendments: microbial contamination in compost and manure amendments." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27364.
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The application of animal manures to agricultural land as a soil organic amendment has been identified as an important route by which foodborne pathogens can enter the human food chain. Knowledge of the presence and incidence of key foodborne pathogens in manure is a vital first step in the establishment of sound and effective guidelines for management and prevention of contamination by manure. The work described in this thesis attempts to determine the persistence of pathogens when raw manures are directly applied to agricultural soils, and treated under thermophilic composting conditions. Results from this study indicated that the current conditions suggested by typical food safety guidelines are sufficient to reduce the population of enteric bacteria to levels that minimise risks associated with culturable cells in raw manure and finished compost. However, E. coli cells have the potential to enter a viable but non-culturable (VBNC) state and are undetected by culture-based monitoring methods, thus providing a false impression of the innate risk of the product. Prc, bamB and tolA, which are responsible for stabilising the cell membrane, were found to be essential genes required for surviving heat treatment at 55°C. In addition, the presence of relA and oxyR suggested that E. coli may use the VBNC state as an adaptive strategy for long-term survival to withstand multiple stresses, including heat stress. Entering the VBNC state with a strengthen cell envelope may help E. coli to survive prolonged heating during standard composting conditions. Successful resuscitation from the VBNC state was achieved in the presence of cell-free supernatant from actively growing E. coli MG1655. These results underline the importance of considering VBNC cells when evaluating the sanitary effect of the composting process. VBNC cells in composts could facilitate the persistence of pathogens in manure-amended soil and thus pose a risk of microbial contamination of fresh produce.
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Nkqenkqa, Vuyiseka. "Metal and microbial contamination of agricultural soil and the Veldwachters River, Stellenbosch, South Africa." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2423.
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Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2017.Surface water is used as a source of water supply in many countries, including South Africa. One of the sources of surface water pollution is leachate and surface runoff from landfills. In agricultural soils, the landfill runoff and leachate deteriorate the quality and affect the fertility of soil. The entry of metals and microorganisms from landfill leachate to adjacent environments is through surface runoff due to rainfall. Adverse effects on human- and environmental health triggers a need to monitor and control contaminants in the environment. The aims of the study are to determine the effect of landfill runoff and leachate on agricultural soil and river water (Veldwachters River) running adjacent to the Devon Valley landfill site and to identify potential metal-tolerant organisms in environmental samples collected in Stellenbosch, Western Cape, South Africa. Samples (agricultural soil, river water and sediments) were collected once a month for a period of six months from the study area for analysis. Physicochemical parameters that are known to have major effects on environmental samples were assessed and the concentrations of various metals (Al, Pb, Cr, Mn, Mo, Co, Ni, Cu, Zn, Fe, Cd and V) were also determined by means of inductively coupled plasma mass spectrometry (ICP-MS). Soil texture analysis was tested in order to monitor the metal distribution in soils under the influence of environmental factors.
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Moritz, Jeldrik [Verfasser], and Knut [Akademischer Betreuer] Wichmann. "Effect of retrograde microbial contamination on mobile drinking water systems / Jeldrik Moritz. Betreuer: Knut Wichmann." Hamburg-Harburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2013. http://d-nb.info/1048574261/34.
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Myers, John R. "Evaluation and Mitigation of the Temporal Evolution of Microbial Contamination Risk in Surface Water Systems." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522418268900325.
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Moritz, Jeldrik Verfasser], and Knut [Akademischer Betreuer] [Wichmann. "Effect of retrograde microbial contamination on mobile drinking water systems / Jeldrik Moritz. Betreuer: Knut Wichmann." Hamburg-Harburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2013. http://d-nb.info/1048574261/34.
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Jiménez, de Duarte Yalimay Mercedes. "Microbial ecosystems of Shark Bay embayments: assessing their functionality and resilience to potential petroleum contamination." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/85089.
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Shark Bay is a protected area which is under risk to be affected by a petroleum spill. An Experimental approach was used to simulate this potential scenario in hypersaline microbial mats from this region. This study has provided new insights and evidence of their biological features that contribute to their ecological resilience and resistance in terms of their microbial composition and functionalities, under short- and long-term petroleum disturbances.
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Geary, Phillip M. "On-site system effluent source tracking using geochemical and microbial tracers in a coastal catchment." Thesis, View thesis, 2004. http://handle.uws.edu.au:8081/1959.7/566.
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The principal aims of this thesis were to examine whether there were hydraulic links between individual on-site wastewater systems in sandy soils at Salt Ash and the Tilgerry Creek estuary near Port Stephens, New South Wales, and whether the chemical and microbiological contaminants from on-site systems could reach surface and groundwaters, and possibly lead to impacts on estuarine oyster growing waters. The research outcomes are contained within the thesis and in four refereed papers presented at conferences, and which have been subsequently published, or are in press. Copies of each of these papers are contained within the thesis Appendices. The presence of faecal contamination from domestic systems in the estuary, and surface drains in particular, has been confirmed by work contained in this thesis. The potential level of risk to human health from the consumption of contaminated oysters is, however, regarded as very low, although an assessment of health risk using established microbial assessment models has not been undertaken
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Lee, Samuel C. "Identifying Hot-Spots of Fecal Contamination in the Royal Spring Karstshed." UKnowledge, 2012. http://uknowledge.uky.edu/ce_etds/2.
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The City of Georgetown, Kentucky relies on a vast karst spring network as a drinking water source. This karst feature has several inputs from sinkholes and streams in the Cane Run Watershed: a watershed associated with a variety of land uses in the recharge area. The recharge area encompasses the area from North Lexington to Georgetown and is composed of urban, suburban, agricultural and industrial usage. A serious water quality issue exists with respect to the impact of fecal contamination within the spring recharge area. Identification of fecal contamination is quantified by microbial indicators adapted from surface water applications: fecal load (E. coli), fecal source (two human-host specific Bacteroides DNA markers) and fecal age (AC/TC ratio). These three criteria are used in a categorical Microbial Source Tracking (MST) model to assign a Sanitary Category Value (SCV) between 0 and 3 for each sample location. Low SCVs (1.5) are associated with high values of fecal load, low fecal age and detectable concentration of human-specific markers. SCV measured during dry weather conditions are indicative of potentially leaking human sewers.
Due to retention and conservation of fecal load (E. coli) and age (AC/TC) microbial indicators in the karstic environment, ambiguous SCV model results cannot pinpoint, with statistical confidence, fecal sources in a karstic environment. Human-host specific genetic markers (HF183 and HuBac) were also detected at all sample sites above limits of detection, indicating steady inflow of fecal material during all sample events. By adding a flow multiplier and expressing HF183 and HuBac values as a load, it was strongly indicated that a human fecal source was entering the groundwater conduit and impacting Royal Spring independent from other upstream fecal sources. Interpretation of these trends, while strongly indicated, cannot be supported with statistical evidence.
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Lefyedi, Mathoto Lydia. "Control of microbial proliferation on sorghum during malting." Thesis, Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-06082007-173213.
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Devine, Nicole. "Microbial Characterization of the Coastal Sediments in an Alabama Beach Impacted by the Deepwater Horizon Spill." Master's thesis, Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/214802.
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Civil EngineeringM.S.Env.E.
The Deepwater Horizon (DWH) blowout, in the Gulf of Mexico, heavily contaminated miles of sandy beaches. Previous experience of petroleum contamination has shown that oil residues can persist in the sediments for decades. Biodegradation is the major mechanism of remediation regarding petroleum hydrocarbons. There is an urgent need to evaluate the competent indigenous microbial biomass in contaminated sediments if the risks posed by toxic oil residues, for the coastal ecosystem, are to be minimized. We report a field investigation during December 2010 and January 2011 regarding measurement of microbial activity in a sandy beach at the Bon Secour National Wildlife Refuge in Alabama. One transect of wells for sampling was installed in the beach; starting with multiport one, being most landward and thought to be least exposed to oil residue and ending with multiport four being the most seaward and exposed to the open waters of the Gulf of Mexico. Sediment samples were collected from different depths purposely chosen from above, inside, and below the oil layers for microbial analysis. Dissolved oxygen (DO) measurements were obtained and temperature was recorded while collecting the oxygen measurements. Pore water samples were collected for nutrient content and were monitored using the multiport sampling wells. Moisture content was analyzed from the sediments extracted at various depths at each well. pH and salinity were also analyzed for their contributing affect on the microbial community. Grain size distribution analyses were conducted on samples collected at all wells and at multiple depths to characterize the field study location. Results show that the bacterial biomass, as measured by Adenosine-5-triphosphate (ATP) and numbers of alkane and polycyclic aromatic hydrocarbon (PAH) degraders determined by Most Probable Number (MPN), are consistently higher in the sediment layers where oil had been detected. A very good correlation was observed among the relative abundance of bacteria in the different samples using MPN and ATP measurements. As expected, ATP based estimates of the microbial populations were two orders of magnitude higher than the alkane and PAH numbers determined by MPN, which reflect the non-cultivability of most environmental bacteria. The lower concentrations of PAH degraders than alkane degraders that were observed in this study are consistent with other studies, even though both populations are lower than in studies involving fresh oil trapped in beach or wetland sediments. PAHs (aromatics) are notoriously more resistant to biodegradation than alkanes, therefore allowing a lower number of biomass to grow using them. The overall smaller size of the bacterial numbers could be explained by the naturally occurring low-organic content of beach sand. On the other hand, this may be due to the highly weathered nature of the oil or it could reflect some other limitation.
Temple University--Theses
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Peixoto, Sara Cristiana Lopes. "Changes of the microbial communities as a mean to evaluate the impact of soil contamination by nanoparticles." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16452.
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Mestrado em MicrobiologiaSilver nanoparticles (AgNPs) are broadly used in the industry due to AgNPs’ antibacterial proprieties. Uncontrolled released of AgNPs and persistence in the environment might enhance the concern of soil contamination by AgNPs. Thus, the aim of this thesis was to evaluate the effects of AgNPs on the bacterial communities using two complementary approaches: a culture-independent method [Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE)] and a culture-dependent method (disc diffusion to analyze the bacterial susceptibility). To explore this aim, the bacterial communities of the LUFA 2.2 soil was exposed to 5 µg/kg of AgNPs or silver cation (Ag+, provided as AgNO3) during 56 days. The analysis of the soil bacterial communities by PCR-DGGE included those retrieved from soil at 42 and 56 days as well as those developed in the presence and absence of Porcellionides pruinosus. For the susceptibility tests, only the soil bacterial communities retrieved from soil at 56 days were analyzed. The first method enabled to investigate the effects of AgNPs or Ag+ on the bacterial community of soil and to understand if these effects changed with the presence of P. pruinosus or along the exposure period. The second methodology provided an analysis of the viable soil bacterial community and allowed to assess the susceptibility responses of the soil bacterial communities according to the silver form (AgNPs or Ag+), silver amounts (10 µg, 1 µg or 0.1 µg), joint exposure to AgNPs and Ag+ and after previous exposure to silver. By using PCR-DGGE, we demonstrated that the silver forms (AgNPs and Ag+), exposure period (42 or 56 days) and the presence of P. pruinosus were relevant to alter the structure of soil bacterial community. P. pruinosus showed to be probably useful to minimize the effects of silver cation for exposures close to 2 months; yet, even in the presence of this isopod, the AgNPs might still be a risk for the soil bacterial communities. By using disc diffusion method we provided an analysis of the viable soil bacterial community demonstrating that the silver form, the amount and the combination of both silver forms affected the susceptibility of the soil bacterial communities. Bacteria were more susceptible to Ag+ than to AgNPs and amount-dependent as well as addition effects were demonstrated. Although the bacterial communities being analyzed by the two methods were different, overall patterns were identified: bacteria are affected by both silver forms, particularly by showing altered community structure and showing susceptibility through growth inhibition. Yet, lower concentrations than those herein tested are imperative to be considered in future investigations as we obtained most of the susceptibility changes for exposures with lower amounts (1 and 0.1 µg). Compared to silver cation, the AgNPs appears to affect less the soil bacterial communities. Thus, this thesis strengthens how valuable is to use these communities to evaluate the effects of the soil contamination as they proved to be sensible to silver contamination by both methodologies.
As nanopartículas de prata (AgNPs) são muito utilizadas na indústria devido às suas propriedades antibacterianas. A libertação de forma não controlada das AgNPs para o ambiente e a sua persistência no mesmo, aumentam a preocupação em relação à contaminação dos solos por AgNPs. Assim, o objetivo desta tese foi analisar os efeitos das AgNPs nas comunidades bacterianas do solo recorrendo a duas abordagens complementares: uma independente do cultivo [Polymerase Chain Reaction- Denaturing Gradient Gel Electrophoresis (PCR-DGGE)] e outra dependente do cultivo (método de difusão por discos para analisar a suscetibilidade bacteriana). Para dar cumprimento a este objectivo, as comunidades bacterianas do solo LUFA 2.2 foram expostas a 5 µg/kg de AgNPs ou de catião prata (Ag+, disponibilizado como AgNO3) durante 56 dias. A análise das comunidades bacterianas do solo por PCR-DGGE foi feita para 42 e 56 dias e na presença e ausência do Porcellionides pruinosus. Para os testes de suscetibilidade, apenas as comunidades bacterianas do solo para 56 dias foram analisadas. O primeiro método possibilitou investigar os efeitos das AgNPs ou Ag+ nas comunidades bacterianas do solo e compreender se estes efeitos alteravam com a presença do P. pruinosus ou ao longo do tempo de exposição. O segundo método permitiu avaliar a resposta de suscetibilidade das comunidades bacterianas do solo atendendo à forma (AgNPs ou Ag+) e quantidade (10 µg, 1 µg ou 0.1 µg) da prata, à exposição conjunta e após reincidência da contaminação por prata. Com o PCR-DGGE demostrou-se que a forma da prata (AgNPs ou Ag+), o período de exposição (42 ou 56 dias) e a presença do P. pruinosus foram relevantes para a alteração da comunidade bacteriana do solo. O P. pruinosus poderá ser, provavelmente, útil para a bioremediação de catião prata para exposições perto dos 2 meses; ainda assim, mesmo na presença deste isópode, as AgNPs poderão constituir um risco para as comunidades bacterianas do solo. Através do método de difusão por discos foi possível disponibilizar uma análise da fracção viável das comunidades bacterianas do solo demonstrando que a forma, quantidade e combinação de ambas as formas de prata afectaram a suscetibilidade das comunidades bacterianas do solo. As bactérias mostraram ser mais suscetíveis Ag+ do que às AgNPs sendo também possível observar uma resposta dependente da quantidade além do efeito aditivo para a exposição combinada. Apesar dos efeitos das nanopartículas de prata nas comunidades bacterianas terem sido analisadas por dois métodos, foram identificados alguns padrões: as bactérias foram afetadas por ambas as formas de prata, mostrando que quer a estrutura da comunidade quer a suscetibilidade eram alteradas. É imperativa a análise de baixas quantidades em investigações futuras, além das testadas nesta tese, já que a resposta de suscetibilidade alterou-se para exposição prévia a contaminações com quantidades baixas (1 e 0.1 µg). Comparativamente com o catião de prata, as AgNPs parecem afetar menos as comunidades bacterianas do solo. Assim, esta tese reforça o quão valioso é usar estas comunidades para avaliar os efeitos da contaminação no solo, já que provaram ser sensíveis à contaminação de prata pelas duas metodologias.
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Nabati, Zahra. "Effect of Yarrowia Lipolytica biofilm on corrosion behavior of carbon steel in simulated biodiesel storage tanks." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513356814768246.
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