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Castilho, Ivana Giovannetti [UNESP]. "Qualidade microbiológica do ambiente e da tilápia-do-Nilo (Oreochromis niloticus) produzida em sistema de tanques-rede no reservatório de Chavantes, SP." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/87790.
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A piscicultura é o setor mais popular da aquicultura e o Brasil tem grande potencial para desenvolvimento da atividade devido às características do país e ao aumento no consumo de peixes. O reservatório de Chavantes, no Médio Rio Paranapanema, possui diversas pisciculturas de tanques-rede com criação de tilápias. No entanto, esses sistemas são intensivos com altas densidades de estocagem e de fornecimento de ração, o que pode ser prejudicial para a qualidade da água e saúde dos animais, trazendo conseqüências ecológicas, econômicas e sociais. Aeromonas e Pseudomonas estão entre os principais patógenos de peixes, porém, no ambiente e na produção de uma piscicultura, uma grande variedade de micro-organismos pode ser identificada sem provocar doenças nos animais, mas sendo via de transmissão de agentes patogênicos para o homem, como Salmonella sp e Staphylococcus aureus. A determinação de coliformes termotolerantes também é de grande importância na vigilância da contaminação por patógenos nos sistemas de criação de peixes. Assim, o objetivo do presente estudo foi avaliar a qualidade microbiológica de pescados tilápia-do-Nilo (Oreochromis niloticus) criados em sistema de tanques-rede no reservatório de Chavantes (médio rio Paranapanema, SP), bem como a qualidade da água e da ração nesses sistemas. As análises foram feitas em quatro ciclos de produção, dois de verão e dois e inverno, através da pesquisa de Pseudomonas sp, Salmonella sp, S. aureus e coliformes termotolerantes (CTe) nos pescados, Salmonella sp e CTe na água e Salmonella na ração. No primeiro ciclo de verão, 8% das amostras de peixes estavam contaminadas com Aeromonas, 4% com Pseudomonas sp e 37,3% das amostras com NMP de CTe/g acima de 103. Não foram detectados Salmonella ou S. aureus. O primeiro ciclo...
Fish farming is the most popular modality of aquaculture and Brazil has great potential for this activity due to its characteristics and increased consumption of fish. The Chavantes reservoir, at Middle Paranapanema River has several fish farms using cages to create tilapia. However, these systems are intensive and therefore use high stocking and feeding densities, which can be detrimental to water quality and animal health. Aeromonas and Pseudomonas are among the main pathogens of fish, but a variety of micro-organism can be identified in the environment and in a fish farm without causing disease in animals, but them can act as a route of disease transmission to humans, as those caused by Salmonella and Staphylococcus aureus. The fecal coliforms determination is also important in surveillance of the contamination by pathogens in fish farming systems. Thus, this study aimed to evaluate the microbiological quality of Nile-tilapia fish (Oreochromis niloticus) cultivated in cages in Chavantes reservoir (Middle Paranapanema River, SP) and water and feed quality in these systems. Analyses were done during four production cycles, two in the summer and two in the winter, by researching Aeromonas sp, Pseudomonas sp, Salmonella, S. aureus and thermotolerant coliforms (TC) in fish, Salmonella and TC in water and Salmonella in feed samples. In the first summer cycle, 8% of the fish samples were contaminated with Aeromonas sp, 4% with Pseudomonas sp and 37.3% with over 103 MPN TC/g. There were no samples with Salmonella or S. aureus. The first winter cycle presented 10% of fish samples with Aeromonas sp, 6.1% with Pseudomonas sp, 1.1% with S. aureus, Salmonella in 0.5% and 58.9% above the allowed limit for TC/g. In the second cycle of summer, 10.6% of the samples were contaminated with Aeromonas sp, 8% with... (Complete abstract click electronic access below)
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Castilho, Ivana Giovannetti. "Qualidade microbiológica do ambiente e da tilápia-do-Nilo (Oreochromis niloticus) produzida em sistema de tanques-rede no reservatório de Chavantes, SP /." Botucatu, 2012. http://hdl.handle.net/11449/87790.
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Orientador: Vera Lucia Mores RallBanca: José Paes de Almeida Nogueira Pinto
Banca: Reinaldo José da Silva
Resumo: A piscicultura é o setor mais popular da aquicultura e o Brasil tem grande potencial para desenvolvimento da atividade devido às características do país e ao aumento no consumo de peixes. O reservatório de Chavantes, no Médio Rio Paranapanema, possui diversas pisciculturas de tanques-rede com criação de tilápias. No entanto, esses sistemas são intensivos com altas densidades de estocagem e de fornecimento de ração, o que pode ser prejudicial para a qualidade da água e saúde dos animais, trazendo conseqüências ecológicas, econômicas e sociais. Aeromonas e Pseudomonas estão entre os principais patógenos de peixes, porém, no ambiente e na produção de uma piscicultura, uma grande variedade de micro-organismos pode ser identificada sem provocar doenças nos animais, mas sendo via de transmissão de agentes patogênicos para o homem, como Salmonella sp e Staphylococcus aureus. A determinação de coliformes termotolerantes também é de grande importância na vigilância da contaminação por patógenos nos sistemas de criação de peixes. Assim, o objetivo do presente estudo foi avaliar a qualidade microbiológica de pescados tilápia-do-Nilo (Oreochromis niloticus) criados em sistema de tanques-rede no reservatório de Chavantes (médio rio Paranapanema, SP), bem como a qualidade da água e da ração nesses sistemas. As análises foram feitas em quatro ciclos de produção, dois de verão e dois e inverno, através da pesquisa de Pseudomonas sp, Salmonella sp, S. aureus e coliformes termotolerantes (CTe) nos pescados, Salmonella sp e CTe na água e Salmonella na ração. No primeiro ciclo de verão, 8% das amostras de peixes estavam contaminadas com Aeromonas, 4% com Pseudomonas sp e 37,3% das amostras com NMP de CTe/g acima de 103. Não foram detectados Salmonella ou S. aureus. O primeiro ciclo... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Fish farming is the most popular modality of aquaculture and Brazil has great potential for this activity due to its characteristics and increased consumption of fish. The Chavantes reservoir, at Middle Paranapanema River has several fish farms using cages to create tilapia. However, these systems are intensive and therefore use high stocking and feeding densities, which can be detrimental to water quality and animal health. Aeromonas and Pseudomonas are among the main pathogens of fish, but a variety of micro-organism can be identified in the environment and in a fish farm without causing disease in animals, but them can act as a route of disease transmission to humans, as those caused by Salmonella and Staphylococcus aureus. The fecal coliforms determination is also important in surveillance of the contamination by pathogens in fish farming systems. Thus, this study aimed to evaluate the microbiological quality of Nile-tilapia fish (Oreochromis niloticus) cultivated in cages in Chavantes reservoir (Middle Paranapanema River, SP) and water and feed quality in these systems. Analyses were done during four production cycles, two in the summer and two in the winter, by researching Aeromonas sp, Pseudomonas sp, Salmonella, S. aureus and thermotolerant coliforms (TC) in fish, Salmonella and TC in water and Salmonella in feed samples. In the first summer cycle, 8% of the fish samples were contaminated with Aeromonas sp, 4% with Pseudomonas sp and 37.3% with over 103 MPN TC/g. There were no samples with Salmonella or S. aureus. The first winter cycle presented 10% of fish samples with Aeromonas sp, 6.1% with Pseudomonas sp, 1.1% with S. aureus, Salmonella in 0.5% and 58.9% above the allowed limit for TC/g. In the second cycle of summer, 10.6% of the samples were contaminated with Aeromonas sp, 8% with... (Complete abstract click electronic access below)
Mestre
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Davies, A. R. "The role and physiology of aquatic minibacteria." Thesis, Cardiff University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373878.
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Hill, Susannah Margaret. "Analysis of tellurite resistance in aquatic bacteria." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329467.
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Lu, Xinxin. "Microbially Mediated Transformation of Dissolved Nitrogen in Aquatic Environments." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1429540424.
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Davis, Katie Sarah. "Biodiversity of aquatic oomycetes in the Falkland Islands." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231638.
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Oomycetes are a diverse group of organisms with worldwide distribution. The phylum contains a large number of pathogenic species which cause immense damage to both animal and plant host species in cultured, managed and wild ecosystems. As such, the majority of research is focused on host-pathogen interactions and the environmental study of oomycetes is greatly neglected. However, due to their devastating economic and ecological effects it is becoming increasingly clear that oomycete ecology and diversity studies are vital to the monitoring and management of diseases caused by oomycete species. By studying oomycete diversity, we further expand our knowledge of species ecological adaptation, distribution and host ranges, allowing for development of improved biosecurity systems. The diversity of oomycete species within the biogeographically important Falkland Island archipelago was assessed. The Islands contained relatively low oomycete species diversity, with a total of twenty-five species identified, in nine genera; Pythium s. str., Phytopythium, Saprolegnia, Leptolegnia, Newbya, Achlya, Elongisporangium, Globisporangium and Phytophthora. Thirteen of the identified species from the Falkland Islands were putative novel species, within the genera; Saprolegnia, Leptolegnia, Newbya, Pythium s. str., Phytopythium and Elongisporangium. Four of these putative novel species were confirmed as novel taxa through the morphological and molecular analyses presented herein. A fifth species requires further analyses to confirm the taxonomic position. One of the presented species was mildly pathogenic towards Atlantic salmon (Salmo salar) eggs, while another was pathogenic towards ryegrass (Lolium sp.) seedlings. These results expand our knowledge of oomycete taxonomy and provide further knowledge of pathogenic oomycete species.
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Albergaria, Furtado Semedo Miguel. "Animal Waste and Antibiotic Impacts on Microbial Denitrification in Terrestrial and Aquatic Ecosystems." W&M ScholarWorks, 2019. https://scholarworks.wm.edu/etd/1582642568.
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The global increase in livestock and poultry production observed in the last decades has led to an increase in animal waste generated. The animal waste contains high levels of nitrogen and may carry antibiotics that can disturb important microbial activities such as denitrification in terrestrial and aquatic ecosystems. Disturbances of microbial denitrification can have detrimental consequences to environmental health. In the terrestrial environment, denitrification is an important source and sink of N2O, a potent greenhouse gas in the atmosphere. In aquatic ecosystems, denitrification is a dominant NO3- removal pathway, contributing to prevent eutrophication. The overall goal of this dissertation is to evaluate the impacts of animal waste and potential antibiotic exposure on microbial communities responsible for denitrification in terrestrial and aquatic ecosystems. To achieve this goal, a combined approach of measuring activity rates and performing a molecular characterization of the microbial communities was used. In Chapter 2, the microbial community changes associated with the impacts of acute antibiotic exposure on denitrification were evaluated in soil microcosms. Antibiotic exposure caused a significant increase in N2O production from denitrification. This increase was paralleled with a greater ratio of fungi:bacteria abundance and lower abundances of particular taxa with N2O reduction capacity. In Chapter 3, the impacts of animal manure and antibiotic contamination on N2O fluxes and the abundance of denitrification genes were investigated in soil mesocosms. N2O fluxes in soils treated with manure fertilizer and tetracycline were considerably higher than in control soils. The manure fertilization and antibiotic exposure had diverse effects on different bacterial taxa responsible for N2O production. In Chapter 4, the denitrification activity and microbial community structure in tidal creek sediments impacted by wastewater discharge from a poultry processing plant were evaluated through a field survey and a microcosm experiment. Denitrification rates were inhibited in the location affected by the wastewater discharge. This decrease in denitrification activity was associated with changes in the microbial community structure, such as a lower relative abundance of bacterial taxa carrying denitrification genes and lower abundance of N2O reducing bacteria. In Chapter 5, the abundance and diversity of antibiotic resistance genes were evaluated in a tidal creek impacted by wastewater discharge from a poultry processing plant. The numbers of antibiotic resistance genes were higher in the location closer to the wastewater discharge, suggesting an historic antibiotic exposure associated with the activity of the poultry processing plant. Overall, this work provides new knowledge of the impacts of animal waste and antibiotics on N2O emissions in terrestrial ecosystems and microbial NO3- removal in aquatic ecosystems. This dissertation emphasizes the functional importance of microbial communities to ecosystem health and their responses to anthropogenic disturbance.
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Gilfillan, Dennis, Timothy Andrew Joyner, and Phillip R. Scheuerman. "Maxent Estimation of Aquatic Escherichia Coli Stream Impairment." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/5480.
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Background: The leading cause of surface water impairment in United States’ rivers and streams is pathogen contamination. Although use of fecal indicators has reduced human health risk, current approaches to identify and reduce exposure can be improved. One important knowledge gap within exposure assessment is characterization of complex fate and transport processes of fecal pollution. Novel modeling processes can inform watershed decision-making to improve exposure assessment.
Methods: We used the ecological model, Maxent, and the fecal indicator bacterium Escherichia coli to identify environmental factors associated with surface water impairment. Samples were collected August, November, February, and May for 8 years on Sinking Creek in Northeast Tennessee and analyzed for 10 water quality parameters and E. coli concentrations. Univariate and multivariate models estimated probability of impairment given the water quality parameters. Model performance was assessed using area under the receiving operating characteristic (AUC) and prediction accuracy, defined as the model’s ability to predict both true positives (impairment) and true negatives (compliance). Univariate models generated action values, or environmental thresholds, to indicate potential E. coli impairment based on a single parameter. Multivariate models predicted probability of impairment given a suite of environmental variables, and jack-knife sensitivity analysis removed unresponsive variables to elicit a set of the most responsive parameters.
Results: Water temperature univariate models performed best as indicated by AUC, but alkalinity models were the most accurate at correctly classifying impairment. Sensitivity analysis revealed that models were most sensitive to removal of specific conductance. Other sensitive variables included water temperature, dissolved oxygen, discharge, and NO3. The removal of dissolved oxygen improved model performance based on testing AUC, justifying development of two optimized multivariate models; a 5-variable model including all sensitive parameters, and a 4-variable model that excluded dissolved oxygen.
Discussion: Results suggest that E. coli impairment in Sinking Creek is influenced by seasonality and agricultural run-off, stressing the need for multi-month sampling along a stream continuum. Although discharge was not predictive of E. coli impairment alone, its interactive effect stresses the importance of both flow dependent and independent processes associated with E. coli impairment. This research also highlights the interactions between nutrient and fecal pollution, a key consideration for watersheds with multiple synergistic impairments. Although one indicator cannot mimic the plethora of existing pathogens in water, incorporating modeling can fine tune an indicator’s utility, providing information concerning fate, transport, and source of fecal pollution while prioritizing resources and increasing confidence in decision making. Methods
We used the ecological model, Maxent, and the fecal indicator bacterium Escherichia coli to identify environmental factors associated with surface water impairment. Samples were collected August, November, February, and May for 8 years on Sinking Creek in Northeast Tennessee and analyzed for 10 water quality parameters and E. coli concentrations. Univariate and multivariate models estimated probability of impairment given the water quality parameters. Model performance was assessed using area under the receiving operating characteristic (AUC) and prediction accuracy, defined as the model’s ability to predict both true positives (impairment) and true negatives (compliance). Univariate models generated action values, or environmental thresholds, to indicate potential E. coli impairment based on a single parameter. Multivariate models predicted probability of impairment given a suite of environmental variables, and jack-knife sensitivity analysis removed unresponsive variables to elicit a set of the most responsive parameters. Results
Water temperature univariate models performed best as indicated by AUC, but alkalinity models were the most accurate at correctly classifying impairment. Sensitivity analysis revealed that models were most sensitive to removal of specific conductance. Other sensitive variables included water temperature, dissolved oxygen, discharge, and NO3. The removal of dissolved oxygen improved model performance based on testing AUC, justifying development of two optimized multivariate models; a 5-variable model including all sensitive parameters, and a 4-variable model that excluded dissolved oxygen. Discussion
Results suggest that E. coli impairment in Sinking Creek is influenced by seasonality and agricultural run-off, stressing the need for multi-month sampling along a stream continuum. Although discharge was not predictive of E. coli impairment alone, its interactive effect stresses the importance of both flow dependent and independent processes associated with E. coli impairment. This research also highlights the interactions between nutrient and fecal pollution, a key consideration for watersheds with multiple synergistic impairments. Although one indicator cannot mimic theplethora of existing pathogens in water, incorporating modeling can fine tune an indicator’s utility, providing information concerning fate, transport, and source of fecal pollution while prioritizing resources and increasing confidence in decision making.
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Surman, Susanne Barbara. "The integration of an avirulent Legionella pneumophila into aquatic biofilms." Thesis, University of Central Lancashire, 1994. http://clok.uclan.ac.uk/1773/.
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A continuous culture model system was set up in the laboratory and inoculated with a diverse range of microorganisms, including several bacteria and protozoa, obtained from the local mains water tap supply. This inoculum and was added to the system without any prior culture or other selection process. Biofilms readily developed on glass tiles suspended in the planktonic phase of the system. An avirulent Legionella pneumophila was inoculated into the system and was subsequently isolated from both biofilms and also from the aqueous(planktonic) phase of the chemostat. The attenuation of this strain, determined by its inability to cause disease and death in guinea pigs, remained unaltered despite the long term survival of this strain within the system. Investigations to determine whether the avirulent L. pneumophila was able to infect and proliferate within protozoa were carried out. The results of the present study show that this avirulent L. pneumophila did not proliferate intracellularly and suggest that the association of L. pneumophila with protozoa although probably important in the long term survival of this bacterium especially during periods where adverse conditions prevail, is not essential but opportunistic. In chapter 3 the importance of the presence of these non-legionellae bacteria, which included Flavobacterium sp., Acinetobacter spp. and several species of Pseudomonas, was investigated. The results suggest that the presence of the non-legionellae are relevant to the survival of Legionella especially in environments which favour it's growth, for example water distribution systems. In order that we may gain a further insight into the ecology of microorganisms in their natural environment, it is necessary to visualise them in conditions which allow them to interact in a way which mimics as closely as possible the natural environment. Biofilms were developed on surfaces which could be removed from the model system in their entirety. Direct visualisation techniques, including atomic force microscopy and Hoffman modulation microscopy could then be used which allowed the in vivo examination of biofilms in situ on the surface upon which they had developed. More traditional microscopy methods were also used. Atomic force microscope images of biofilms and individual biofilm bacteria including Legionella were obtained, which clearly showed the presence of exopolymeric substances (EPS). Hoffman modulation contrast microscopy and scanning electron microscopy showed the diverse nature of the biofilms being studied. The results of these investigations suggest that a more complete understanding of the complex nature of biofiims is achieved by the use of a combination of several microscopy techniques. The response of a L. pneumophila serogroup 6 and the avirulent L. pneumophila serogroup 1 to a commercially available biocide, Vantocil IB, was investigated. Both the serogroup 6 and the avirulent serogroup 1 could not be detected following biocide teatment in either the planktonic phase or biofilms. These results suggest that this avirulent L. pneumophila is a suitable model substitute for the virulent L. pneumophila.
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Loh, Chi Leong. "The hollow fiber diffusion system: A novel method for the in situ survival studies in the aquatic environment." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6875.
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The Hollow Fiber Diffusion (HFD) system is a novel approach for the in situ study of the survival of bacteria and viruses in the aquatic environment. The HFD system employs a tangential flow, hollow fiber cartridge with a large area $(7 \times 10\sp3$ cm$\sp2$) of exchange surfaces for diffusion. When compared with diffusion chambers, the HFD system responded significantly faster and more accurately to changes in pH, Eh, nutrient concentrations and to the presence of disinfectants in the external aqueous environment. The T$\sb$ diffusion of low molecular weight substrates was 0.6 h for the HFD system but was 4.2 h for the diffusion chamber. The rate of diffusion or equilibration could be further improved by increasing the flow rate through the HFD system or reducing the volume of the sample reservoir. The HFD system was compatible with all test bacteria and viruses with the possible exception of tailed coliphages. The inactivation of tailed phages by the HFD system can be reduced or eliminated using a slower flow rate or larger diameter hollow fibers. Tailed coliphage inactivation in the HFD system was not apparent in natural waters. Neither adsorption of microorganisms to the hollow fiber membrane surfaces nor colonization of those surfaces was found to be a significant problem during its use in natural waters. A protocol for the decontamination and reuse of the hollow fiber cartridges using hydrogen peroxide was developed and applied successfully. The results of trials of the HFD system at five field sites suggests that the HFD system permits "real-time" accommodation to changes in the physicochemical parameters of the external aqueous environment which can influence the survival of microorganisms. Differences in the survival of microorganisms in the HFD system and in batch samples were shown. The HFD system demonstrated regrowth of Escherichia coli in the Rideau River which is an eutrophic, temperate river. It also demonstrated a diurnal inactivation pattern for Enterococcus durans with the slower decay of E. durans numbers in the hours of darkness. For the other water sources tested (the Ottawa River, the Kennedy Burnett Stormwater Ponds, the Gombak River and the Kroh River), the general order of survival of test microorganisms was MS-2 coliphage $>$ poliovirus $>$ phage B $>$ E. coli and E. durans. In the Rideau River, the order of survival was E. coli $>$ poliovirus $>$ MS-2 coliphage $>$ E. durans. Surprisingly, there was no significant difference in the survival of microorganisms in the two equatorial rivers compared with the survival of the organisms in the oligotrophic, temperate Ottawa River. The HFD system will be very useful in studying the survival and natural ecology of microorganisms in the aquatic environment. It can be applied to model the behavior of water quality indicators, pathogenic organisms and genetically engineered microorganisms. It also has potential for ecotoxicological studies, monitoring for toxins or pollutants in the environment and for the in-line monitoring of the efficiency of water treatment processes such as chlorination.
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Gilfillan, Dennis, Timothy A. Joyner, and Phillip Scheuerman. "Maxent Estimation of Aquatic Escherichia Coli Stream Impairment." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/5587.
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Background.The leading cause of surface water impairment in United States’ rivers and streams is pathogen contamination. Although use of fecal indicators has reduced human health risk, current approaches to identify and reduce exposure can be improved. One important knowledge gap within exposure assessment is characterization of complex fate and transport processes of fecal pollution. Novel modeling processes can inform watershed decision-making to improve exposure assessment.
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Murray, Aimee Kaye. "Selection for antibiotic resistance in the aquatic environment : novel assays to detect effect concentrations of micropollutants." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/30325.
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The environment is increasingly recognised as a key player in the emergence and mobilisation of antibiotic resistance, which negatively impacts human health, healthcare systems, and farming practices worldwide. Recent work has demonstrated concentrations of antibiotics in the natural environment may select for resistance in situ, but a scarcity of meaningful data has prevented rigorous environmental risk assessment of antibiotics. Without such data, mitigation strategies, such as improved antibiotic stewardship or environmental discharge limits, cannot be effectively designed or implemented. This thesis designed and developed two methods for determining effect concentrations of antibiotics in complex microbial communities, thereby generating a significant amount of data to address this knowledge gap. Minimal selective concentrations (MSCs) were determined in long term selection experiments for four classes of antibiotic at concentrations as low as 0.4 μg/L, which is below many measured environmental concentrations. Lowest observed effect concentrations were determined using a short term, growth based assay which were highly predictive of MSCs. A novel finding was significant selection for cefotaxime resistance occurred at a wide range of antibiotic concentrations, from 125 μg/L - 64 mg/L, which has important clinical implications. Determination of MSC in single species assays was also shown to be a poor predictor of MSC in a complex microbial community. Co-selection for antimicrobial resistance was demonstrated in selection experiments and through improved understanding of class 1 integron evolution, assessing selective effects on resistance gene acquisition using a novel PCR method and next-generation sequencing. In the final study, a novel resistance determinant (UDP-galactose 4-epimerase) conferring cross-resistance to biocides and antibiotics was discovered, providing a target for further study. These findings indicate selection and co-selection for antimicrobial resistance is likely to occur in the environment, and provides the means to rapidly generate further data to aid in the development of appropriate mitigation strategies.
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Smith, Garrett J. "Microbial contributions to carbon, nitrogen, and greenhouse gas cycling in freshwater terrestrial-aquatic interfaces." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1575380962535345.
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Marti, Serrano Elisabet. "Occurrence of antibiotic resistance genes in aquatic microbial communities exposed to anthropogenic activities." Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/671847.
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The overuse of antibiotics has led to the selection of resistant strains. This thesis investigated the occurrence of antibiotic resistance genes (ARGs) in aquatic microbial communities influenced by anthropogenic activities.
In this study, qPCR assays were designed to quantify the plasmid-mediated quinolone resistance in environmental samples. Then, several ARGs conferring resistance to several groups of antibiotics were quantified in biofilms and sediments from a wastewater treatment plant (WWTP) discharge point and the receiving river. Ciprofloxacin-resistant strains were also isolated an screened for the presence of qnr genes and aac(6’)-Ib-cr and their association with extended-spectrum β-lactamases. A multidrug resistance-encoding plasmid from an Aeromonas sp. was further characterized.
Overall, ARGs were detected in different matrices (water, biofilm and sediment), both in bacteriophages and bacteria, and different sources (rivers, effluents from several human and veterinary hospitals, subterranean water, chicken faeces and WWTP effluents), indicating that these emerging pollutants are widely distributed in the environments exposed to anthropogenic activitiesL'ús excessiu d'antibiòtics ha portat a la selecció de soques resistents. En aquesta tesi es va investigar l'aparició de gens de resistència als antibiòtics (ARGs) a les comunitats microbianes aquàtiques impactades per activitats antropogèniques. En primer lloc, es van dissenyar assajos de qPCR per quantificar gens de resistència a quinolones localitzats en plàsmids. A continuació, es van quantificar diversos ARGs que confereixen resistència a diversos grups d'antibiòtics en biofilms i sediments d'un punt d'abocament d'una planta de tractament d'aigües residuals (EDAR) i del riu receptor. També es van aïllar soques resistents a la ciprofloxacina i es va analitzar la presència de gens qnr i aac (6')-Ib-cr i la seva associació amb beta-lactamases d'ampli espectre. Per acabar, es va caracteritzar un plàsmid multiresistent procedent d'Aeromonas sp. En general, es van detectar ARGs en diferents matrius (aigua, biofilm i sediments), tant en bacteriòfags com a bacteris, i en diferents fonts (rius, efluents de diversos hospitals humans i veterinaris, aigües subterrànies, excrements de pollastre i efluents d'EDAR) , el que indica que aquests contaminants emergents estan àmpliament distribuïts en els ambients exposats a activitats antropogèniques
Programa de Doctorat en Ciències Experimentals i Sostenibilitat
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Cregger, S. S., and Phillip R. Scheuerman. "A Rapid Biochemical Test Using Cell Lines for Measuring Chemical Toxicity in Aquatic Systems." Digital Commons @ East Tennessee State University, 1993. https://dc.etsu.edu/etsu-works/2896.
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Li, Wei. "INFLUENCE OF ENVIRONMENTAL DRIVERS AND INTERACTIONS ON THE MICROBIAL COMMUNITY STRUCTURE IN PERMANENTLY STRATIFIED MEROMICTIC ANTARCTIC LAKES." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1469757316.
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Van, Gray Jonathon B. "Disturbance effects on assembly and recovery dynamics of freshwater microbial biofilm communitieis." Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1556556989587688.
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Roberto, Alescia. "METAL EFFECTS ON FRESHWATER MICROBIAL COMMUNITY COMPOSITION, STRUCTURE, AND FUNCTION IN AN URBAN STREAM." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1543839535987157.
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Pokhrel, Lok R., Thilini Silva, Brajesh Dubey, Badawy Amro M. El, Thabet M. Tolaymat, and Phillip R. Scheuerman. "Rapid Screening of Aquatic Toxicity of Several Metal-Based Nanoparticles Using the Metplate™ Bioassay." Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/etsu-works/2873.
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Current understanding of potential toxicity of engineered nanomaterials to aquatic microorganisms is limited for risk assessment and management. Here we evaluate if the MetPLATE™ test can be used as an effective and rapid screening tool to test for potential aquatic toxicity of various metal-based nanoparticles (NPs). The MetPLATE bioassay is a heavy metal sensitive test based on β-galactosidase activity in Escherichia coli. Five different types of metal-based NPs were screened for toxicity: (1) citrate coated nAg (Citrate-nanosilver), (2) polyvinylpyrrolidone coated nAg (PVP-nAg), (3) uncoated nZnO, (4) uncoated nTiO2 and (5) 1-Octadecylamine coated CdSe Quantum Dots (CdSe QDs); and compared with their corresponding ionic salt toxicity. Citrate-nAg was further fractionated into clean Citrate-nAg, unclean Citrate-nAg and permeate using a tangential flow filtration (TFF) system to eliminate residual ions and impurities from the stock Citrate-nAg suspension and also to differentiate between ionic- versus nano-specific toxicity. Our results showed that nAg, nZnO and CdSe QDs were less toxic than their corresponding ionic salts tested, while nano- or ionic form of TiO2 was not toxic as high as 2.5 g L− 1 to the MetPLATE™ bacteria. Although coating-dependent toxicity was noticeable between two types of Ag NPs evaluated, particle size and surface charge were not adequate to explain the observed toxicity; hence, the toxicity appeared to be material-specific. Overall, the toxicity followed the trend: CdCl2 > AgNO3 > PVP-nAg > unclean Citrate-nAg > clean Citrate-nAg > ZnSO4 > nZnO > CdSe QDs > nTiO2/TiO2. These results indicate that an evaluation of β-galactosidase inhibition in MetPLATE™ E. coli can be an important consideration for rapid screening of metal-based NP toxicity, and should facilitate ecological risk assessment of these emerging contaminants.
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Craig, C. L., Phillip R. Scheuerman, G. R. Lanza, and J. L. Farris. "The Effects of Water Quality Changes Due to Highway Construction on Aquatic Insects as Measured by the DHA-INT Assay." Digital Commons @ East Tennessee State University, 1993. https://dc.etsu.edu/etsu-works/2897.
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Young, Suzanne M. "The Ecology of Antibiotic Resistance: Sources and Persistence of Vancomycin-Resistant Enterococci and Antibiotic Resistant Genes in Aquatic Environments." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/7112.
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The growing crisis of antibiotic resistance is a major threat to ecosystems and human health. Infections caused by known and emerging antibiotic resistant pathogens are on the rise globally, with approximately 700,000 deaths per year caused by antibiotic resistant bacteria (1). In the United States, infections from antibiotic resistant bacteria cause more than 2 million illnesses and 23,000 deaths (2). Antibiotic resistant bacteria and antibiotic resistance genes are released into aquatic ecosystems through hospital waste, residential sewer lines and animal agricultural waste streams. Animal agriculture accounts for approximately 70% of antibiotic use in the United States (3). In agricultural ecosystems, runoff, land-applied fertilizer and waste lagoons can all contribute to the spread of antibiotic resistance. In urban ecosystems, sewage spills and other wastewater inputs contribute to the spread of antibiotic resistance. Environmental matrices, such as soil and water, can provide habitat, serving as reservoirs to potentially promote the spread of resistance. Research addressing antibiotic resistance primarily focuses on monitoring clinical occurrence and nosocomial infections (acquired in hospitals),but the natural environment also plays a role in the spread of antibiotic resistance. The consequences to aquatic ecosystems are not often studied and not well understood. Antibiotic resistance genes can transfer between bacteria through transduction, transformation and conjugation, potentially persisting in non-pathogenic environmental bacteria. Environmental reservoirs of antibiotics, antibiotic resistant bacteria and antibiotic resistance genes should be considered and integrated into frameworks to improve monitoring, regulation and management of urban and rural watersheds.
The research presented in this doctoral dissertation includes field and laboratory studies designed to assess the prevalence and persistence of antibiotic resistant bacteria and antibiotic resistance genes in aquatic environments, with a focus on vancomycin-resistant enterococci, which are considered a major threat in the United States and top priority pathogens according to the Centers for Disease Control (2). The vanA gene associated with high-level resistance is located on mobile plasmids and associated with clinical infections, predominantly in the species Enterococcus faecium. E. faecium can cause bacteremia, endocarditis, pelvic infections and more (4). When vancomycin, often the last line of treatment for these infections, is no longer effective, the health burdens increase both financially and physically and infections can be fatal.
Chapter 1 summarizes background and review of antibiotic resistance in the environment, including a co-authored review of culture-based methods to detect antibiotic resistant bacteria and antibiotic resistance genes in in the environment (previously published in the Journal of Environmental Quality (5). In Chapter 2, a field study was performed to investigate the occurrence and persistence of vancomycin-resistant enterococci and vanA in a sewage spill in Pinellas County, Florida, previously published in the journal Applied and Environmental Microbiology (6). In Chapter 3, antibiotic resistance genes were quantified to study their persistence in poultry litter microcosms (manuscript in prep). In Chapter 4, microcosms were used to assess how nutrients and plasmid-associated vancomycin resistance affect survival among E. faecium strains (in process of submitting for publication at Applied and Environmental Microbiology).
Antibiotic resistance is a public health crisis and the results of the studies presented here contribute data towards a better understanding of environmental reservoirs of antibiotic resistant bacteria and antibiotic resistance genes. The research has broad implications for public health, environmental policy and ecosystem management.
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Knackstedt, Kathryn Ann. "Rivers as Sources of Freshwater Ice-Nucleating Particles." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1498766754881706.
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Galvão, Juliana Antunes. "Qualidade microbiológica da água de cultivo e de mexilhões Perna perna (Linnaeus, 1758) comercializados em Ubatuba, SP." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/11/11141/tde-16092004-164101/.
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O consumo de moluscos bivalves pode representar sérios riscos à saúde pública, pois refletem diretamente as condições do meio ambiente. Desta forma considera-se de extrema importância o consumo de mexilhões livres de contaminação. Esta pesquisa objetivou estudar a qualidade microbiológica das águas e mexilhões de três pontos de cultivo do município de Ubatuba, SP, a saber: Engenho da Almada, Barra Seca e Costão do Cedro em um período compreendido entre novembro de 2002 e março de 2003, totalizando 5 coletas mensais. Analisou-se na água: Bacillus cereus, Clostrídios Sulfito Redutores, Aeróbios Mesófilos, Staphylococcus aureus, Coliformes totais e fecais, Enterococos e Salmonella. Nos mexilhões foram analisados os mesmos microrganismos citados para água mais o Clostridium perfringens. Os resultados encontrados tanto para as análises de água como dos mexilhões foram satisfatórios, condizentes com a legislação brasileira em vigor, salvo a coleta do mês de março, do cultivo da Barra Seca, onde a média dos valores encontrados para coliformes fecais na água (5,7x101 NMP/100mL) foi superior ao recomendado pela legislação sendo detectado também neste mesmo cultivo e mês, presença de Salmonella em 25 g nas amostras de mexilhões. Mesmo que as contagens de S. aureus e B. cereus na carne estejam de acordo com a legislação em vigor, cuidados devem ser tomados quanto ao armazenamento e a forma de consumo. Averiguou-se a intensidade de interferências sazonais na contagem microbiana na água e constatou-se que a tábua de marés e o índice de insolação diária tiveram uma correlação negativa baixa, ao contrário do índice pluviométrico que apresentou correlação positiva alta.The consumption of bivalve mollusks can represent serious risks to the public health, because they reflect the conditions of the environment directly. This way it is considered of extreme importance the consumption of mussels without contamination. This work aims of studing the water and mussels microbiology quality from three different seafood farms in Ubatuba, SP, to know: Engenho da Almada, Barra Seca and Costão do Cedro from November 2002 to March 2003, totaling five monthly. It was analyzed in the water: Bacillus cereus, Total Clostridia, Aerobic Mesophilic, Staphylococcus aureus, total and fecal coliforms, Enterococci and Salmonella. In the mussels the same microorganisms were analyzed mentioned for water more Clostridium perfringens. The results found in the water and in the mussels were satisfactory, suitable with the Brazilian legislation, except for the sample at Barra Secas beach, in March. The average of the values found at that place for fecal coliformes in the water was higher (5,7x101 MPN/100mL) than the recommended by the legislation. Even in this collection, it was also detected Salmonella in 25 g of mussels. Even if the counts of S. aureus and B. cereus in the mussesls are in agreement with the legislation in vigor cares they should be taken with relationship to the storage and the consumption form. The intensity of seasonal interferences was discovered in the microbial count in the water, in which was verified that the board of tides and the index of daily heatstroke had a low negative correlation unlike the index pluviometric it presented high positive correlation
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Cariani, Zev. "Impact of simulated polar night on Antarctic mixotrophic and strict photoautotrophic phytoplankton." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1547204599969081.
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Mukherjee, Maitreyee. "Identification, enumeration, and diversity of ammonia-oxidizing archaea in the Laurentian Great Lakes." Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1368022892.
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Mosier, Damon Kurtis. "USING SINGLE-CELL SORTING, FISH AND 13C-LABELING TO CULTIVATE AND ASSESS CARBON SUBSTRATE UTILIZATION OF ‘AIGARCHAEOTA’ AND OTHER NOVEL THERMOPHILES." CSUSB ScholarWorks, 2019. https://scholarworks.lib.csusb.edu/etd/930.
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‘Aigarchaeota’, a deeply branching lineage in the domain Archaea with no cultivated representatives, includes both thermophilic and hyperthermophilic microorganisms that reside in terrestrial and marine geothermal environments. The ‘Aigarchaeota’ consists of at least nine proposed genus-level groups that have been confirmed via 16S rRNA sequencing, with ‘Aigarchaeota’ Group 1 (AigG1) being the focus of this study. Based on cultivation-independent genomic data available from several AigG1 members in Great Boiling Spring (GBS), NV, and Yellowstone National Park, 22 different types of growth media were designed and tested for their ability to support growth of AigG1. One of these cultures, G1-10, was found to contain AigG1 at ~5% abundance, as well as other novel thermophilic microbial groups including a new species of the genus Pyrobaculum, members of the candidate phyla ‘Calescamentes’ and ‘Fervidibacteria’, and the novel archaeal lineage NAG1 (‘Geoarchaeota’). To attempt to obtain pure cultures of AigG1 and other novel thermophiles, a single-cell sorting system using an optical trap and a microfluidic device was constructed. The system was validated by sorting E. coli cells, which demonstrated that single, viable cells could be reliably obtained. Using this single cell sorting device on the G1-10 culture, a pure culture of a member of the genus Pyrobaculum was obtained, which was shown to represent a distinct species in this phylum by whole genome sequencing and in silico DNA-DNA hybridization. Additionally, a pure culture of the first representative of the candidate phylum ‘Fervidibacteria’ from an enrichment culture derived from G1-10. Additionally, to aid in morphology-based sorting of AigG1 and stable isotope labeling studies, fluorescence in situ hybridization (FISH) based on catalyzed reporter deposition (CARD-FISH) were developed and an AigG1-specific probe was tested. CARD-FISH was successfully used to detect AigG1 in both the G1-10 culture and in natural sediment samples from GBS. Stable isotope labeling incubations were performed with a variety of 13C-labeled substrates (bicarbonate, amino acids, sugars, and short chain fatty acids) on GBS sediments and G1-10 culture samples, and CARD-FISH was used to specifically detect AigG1 in the fixed samples. Nanometer-scale secondary-ion mass spectrometry (nano-SIMS) will then be used to determine whether AigG1 was capable of taking up the different carbon substrates tested. Overall, the results and accomplishments from this project and follow up nano-SIMS analysis will allow a better understanding of the metabolic potential of AigG1 and will aid future efforts to attempt to obtain pure cultures of this novel lineage.
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Otte, Hillary K. "CONTROL AND PASSIVE TREATMENT OF RUNOFF FROM HORSE MUCK STORAGE STRUCTURES USING RAIN GARDENS." UKnowledge, 2012. http://uknowledge.uky.edu/forestry_etds/11.
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Runoff from livestock operations may contain a variety of pathogens and high levels of nutrients and other harmful contaminants, and is of particular concern in central Kentucky as watersheds are threatened by waste generated from a high concentration of equine activity. Rain gardens are a type of stormwater management tool used to capture and passively treat runoff. This project aimed to incorporate rain gardens into the horse muck storage structures at a thoroughbred facility in the Canr Run watershed in Lexington, Kentucky. Water quality data from soil water within two rain garden muck pads and two control pads, and grab samples from the stream were compared. No significant differences were observed, but trends revealed higher levels of nitrate and phosphate in rain gardens compared to controls, while total organic carbon and E. coli levels were lower in the rain gardens, suggesting that the rain gardens are trapping nutrients while reducing organic matter and killing bacteria. E. coli populations were lower in stream sample locations near rain garden muck pads compared to further downstream near controls. Management recommendations include further improvement of muck storage structures, replacing old muck pads, and changing management and housekeeping habits and attitudes towards environmental responsibility.
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D'souza, Nigel A. "Psychrophilic diatoms in ice-covered Lake Erie." Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1332431260.
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Kotkowski, Rachel. "Environmental Influences on Bacterio-phytoplanktonic Coupling and Bacterial Growth Efficiency in a Sub-tropical Estuary." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1155.
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Bacterio-phytoplanktonic coupling and bacterial growth efficiency (BGE) measurements were used to analyze microbial trophic dynamics and the influence of environmental factors in Florida Bay, Florida. Phytoplankton gross primary productivity (GPP) was measured using 24-hour in situ oxygen incubations; bacterial productivity (BP) was measured using 3H- thymidine incorporation. Weak bacterio-phytoplanktonic coupling was observed over the sampling period. BP was more influenced by local total nitrogen concentrations while GPP was more evenly distributed. BGE rates were low but consistent with marine and estuarine ecosystems worldwide. Results suggest that bacterioplankton growth in Florida Bay is relatively uncoupled from phytoplankton production, which may be due in part to the low levels of phytoplankton biomass in the water column, the large amount of seagrass-derived DOM production in this shallow lagoon, the loading of nitrogen and organic matter associated with terrestrial runoff, and/or their combination.
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Ghosh, Suchismita. "UTILIZATION OF DIFFERENT FORMS OF NITROGEN BY HETEROTROPHIC BACTERIA UNDER VARYING ORGANIC CARBON CONCENTRATIONS: FROM ISOLATES TO COMMUNITIES." Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1374844259.
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Brown, Tanya. "Phenomenological and Molecular Basis of the Cnidarian Immune System." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3468.
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Coral reefs are one of the most diverse ecosystems on the planet due partially to the habitat structure provided by corals. Corals are long lived organisms that can live for hundreds of years and as a result growth of many species is very slow. As a result of this, recovery of corals from disease outbreaks is very slow and difficult and therefore the ecosystem is deteriorating rapidly. Due to this increase in disease and its detrimental effect on coral reefs, it has become imperative to study how corals respond to disease outbreaks. The response of the coral to pathogens is believed to be controlled by the innate immune system. However, the immune pathways and components of these pathways used by cnidarians to combat pathogens are still rudimentary. This work showed that C3 and heat shock protein 70 are components of the coral immune system that positively respond to disease occurrence. As disease out breaks become more frequent, the question has arisen as to whether cnidarians have homologs to of the adaptive immune system that allow them to respond more rapidly to subsequent encounters with the same bacterium. In the cnidarian model system Exaiptasia pallida, immune priming occurs up to one month after the initial sub lethal exposure to the pathogen. This transient form of priming could be the result of host energy allocation in place of establishing long term immune priming which could be too energetically costly. Cnidarians may only activate priming during summer months, when ocean temperatures and bacterial load are high. Specificity of immune priming in E. pallida requires further investigation with more bacterial pathogens. In this dissertation, one bacterial strain shows specificity while the other does not. Furthermore, the priming response involves many pathways which include pathogen recognition, inflammation, and activation of NF-κB. The discovery of immune priming in a sea anemone shows that this phenomenon evolved earlier in the tree of life than previously thought. Additionally, identification of priming in E. pallida is suggestive of its presence in corals which would allow for potential vaccinations of vulnerable corals.
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Servais, Shelby M. "Changes in Soil Microbial Functioning in Coastal Wetlands Exposed to Environmental Stressors and Subsidies." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3821.
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Environmental perturbations are ubiquitous features of ecosystems and shape ecological structure and function. Climate change will alter the intensity and frequency of disturbances and expose ecosystems to novel combinations of useful inputs (subsidies) and harmful inputs (stressors). Coastal wetlands are particularly vulnerable to changing environmental conditions and are increasingly exposed to effects of interacting subsidies and stressors. In particular, the Florida Coastal Everglades, which has experienced accelerated change due to a history of water management practices, is vulnerable to new disturbances associated with climate change. The low-lying Florida Everglades faces multiple disturbances from storm surge, nutrient enrichment, and sea-level rise which will influence its responses to future environmental perturbations. Microbial communities are often used to characterize environmental change because of their high surface area to volume ratio, permeable membrane, and quick turnover rates. Therefore, assessing how microbial function changes can provide insights into how subsidies and stressors interact to alter biogeochemical cycles. I tested how nutrient enrichment can alter ecosystem responses to stress and found that it did not promote recovery in mangrove plants. I examined how long-term exposure to salinity and phosphorus (the limiting nutrient in the Everglades) affected microbial enzyme activity and found that salinity alone acts as a suppressor of enzyme activity but phosphorus addition can mitigate salinity stress in sawgrass soil. I tested how pulses of salinity can affect the microbially-mediated breakdown of organic material and found that the microbial community was functionally redundant and unaffected by saltwater pulses; however, microbial activity was consistently lower in the brackish marsh compared to the freshwater marsh. I investigated how gradients of salinity and phosphorus affected freshwater and brackish soils and determined previous exposure to saltwater intrusion dominates affects microbial function and soil composition. Across these experiments, I found that environmental perturbations alter the microbial-mediated processing of nutrients and carbon, and legacies of previous disturbances influence the microbial response to new disturbance regimes.
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Akins, Leighannah. "Understanding the relationship between bacterial community composition and the morphology of bloom-forming Microcystis." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1543502274681124.
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Martindale, Jane. "Genetics of gas vacuolation in Ancylobacter aquaticus." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390146.
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Gordon, Skyler A. "An Assessment of Potential False Positive E.coli Pyroprints in the CPLOP Database." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1730.
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The genetic information found in each species of organism is unique, and can be used as a tool to differentiate at the molecular level. This has caused rapid genotyping methods to become the cornerstone of a new area of research dependent on reading the genome as a form of identification. One of these specific identification methods, known as pyroprinting, relies on the small variation of DNA sequences within the same species to develop a unique, reproducible fingerprint. By simultaneously pyrosequencing multiple polymorphic loci within the ribosomal operons known as the intergenic transcribed spacers, a reproducible output is obtained, known as a pyroprint, which can be used like a fingerprint to identify that organism. This section of the genome not only differs between species but also between isolated bacteria within that species, allowing for the differentiation of species subtypes, referred to as strains. While this is a viable method for generating reproducible fingerprints from individual strains it may be possible to obtain identical fingerprints from non-identical organisms. The following report uses direct sequence comparison and in silico pyrosequencing of E. coli isolates housed in the Center for Applications in Biotechnology at California Polytechnic State University, San Luis Obispo that have matching pyroprints to show that it is possible to receive near identical pyroprints from non-identical sequences of intergenic transcribed spacers. Although the exact likelihood and cause of this false positive result remains undetermined due to limitations in the sequencing method, its existence questions the accuracy of using pyroprints of the ITS regions as a method of strain classification.
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Ouattara, Koffi Nouho. "Etude et modélisation de la contamination fécale des rivières du bassin de l'Escaut." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209685.
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Le bassin versant de l’Escaut (20 000 km²) est caractérisé par forte densité de population (plus de 500 habitants par km2) et une activité agro-pastorale intensive. Les rivières de ce bassin sont sévèrement affectées par les rejets d’eaux usées domestiques, les effluents d’élevage et les eaux de ruissellement des sols agricoles. Le but de cette étude est :(i) d’évaluer la qualité microbiologique de ces rivières ;(ii) d'identifier et de quantifier les différentes sources de contamination fécale à l’échelle du bassin de l’Escaut; (iii) d’étudier les processus qui contrôlent le devenir des bactéries fécales en rivière; (iv) de développer des modèles numériques sur la base des travaux expérimentaux permettant de prédire la concentration des bactéries indicatrices dans les rivières du bassin de l’Escaut.L’évaluation de la qualité microbiologique des principales rivières du bassin est basée sur le dénombrement de deux indicateurs de contamination fécale (Escherichia coli et entérocoques intestinaux). Les abondances des deux indicateurs dans les principales rivières du bassin indiquent très clairement que les eaux et les sédiments de ces rivières sont fortement contaminés par des micro-organismes entériques. Les sources prédominantes de la pollution fécale de ces rivières sont les rejets des effluents des stations d’épuration. Les niveaux de contamination les plus élevés sont observés dans la Senne en aval de Bruxelles et s’expliquent par le faible débit de la Senne comparé aux débits des effluents des deux stations d’épuration de Bruxelles. Les niveaux de contamination atteignent leur maxima à l’aval de Bruxelles par temps de pluie en raison des surverses de réseaux unitaires.
Les connaissances acquises sur les apports des bactéries indicatrices par les sources ponctuelles et les sources diffuses et sur le devenir des bactéries indicatrices ont permis de développer un module décrivant la dynamique des E. coli dans les rivières. Ce module est original par le fait de considérer trois compartiments de bactéries fécales (libres, attachées aux particules dans la colonne d’eau et présentes dans les sédiments) qui sont affectés différemment par les processus de transport et de disparition. Ce module a été couplé à deux modèles décrivant l’hydrodynamique respectivement de l’ensemble des rivières du bassin (SENEQUE-EC) et de la partie fluviale de l’Escaut sous l’influence de la marée et son estuaire (SLIM-EC2). Ces deux modèles permettent de décrire la distribution temporelle et spatiale des E. coli dans les eaux de surfaces et de prévoir les modifications de la qualité microbiologique des eaux suite à des changements de gestion des eaux usées.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Madhuri, Sumeda. "Polyamine Transformation by Bacterioplankton in Freshwater Ecosystems." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent150114771851742.
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Warhurst, Billy Christopher. "Effects of Elevated Salinity and Oxidative Stress on the Physiology of the Toxigenic Cyanobacterium Microcystis Aeruginosa." UNF Digital Commons, 2014. http://digitalcommons.unf.edu/etd/523.
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Harmful algal blooms (HABs) are found worldwide, particularly in places where warm, well-lit, and stagnant waters are common. HABs can have negative effects on aquatic plants and wildlife due to the reduction in light availability associated with turbidity, decrease in O2 availability, and the production of secondary metabolites that can harm or even prove lethal. Aquatic ecosystems are regularly being affected by elevated salinity because of recent water management strategies, episodes of drought, and salt water intrusion. This research focused on how salinity levels ranging from 0-10ppt affected physiological attributes such as cellular growth and abundance, cell mortality, toxin release, and oxidative stress in the toxigenic cyanobacterium, Microcystis aeruginosa. It was determined that salinity treatments of 7ppt and above caused a decrease in both cellular growth and abundance, as well as an increase in toxin release due to cell mortality. M. aeruginosa was able to survive in salinities up to 7ppt. A pattern of caspase activity in response to elevated salinity was shown, but whether cellular mortality was due solely to programmed cell death (PCD) was not definitive. A strong antioxidant response, measured through catalase activity, was noted when salinity was enhanced to 7ppt. Above this value, the damaging effects of salinity caused elevated levels of reactive oxygen species (ROS) production and cell death. It was determined that the maximum amount of hydrogen peroxide that M. aeruginosa could withstand without significant impact to growth and abundance was below 250µM. Salinities of 7ppt and above had a negative impact on the physiology of M. aeruginosa, leading to cell death and an increase in microcystin release into the environment. These two factors can lead to fish kills, poor drinking water, and other recreational and commercial problems for an aquatic ecosystem. By determining the precise salinity that HAB cellular mortality is imminent, predictive models can be employed to predict the impacts of salt intrusion and groundwater management.
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Fyffe, Deanna Lynne. "Methods to Monitor Lake Erie's Harmful Algal Blooms: A Fellowship with the Cooperative Institute for Great Lakes Research." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1511971289649061.
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Rodriguez-Palacios, Alexander. "Ecology and Epidemiology of Human Pathogen Clostridium difficile in Foods, Food Animals and Wildlife." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313582304.
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Ormiston, Anna Kathleen. "ENVIRONMENTAL, SPATIAL AND TEMPORAL EFFECTS ON MICROBIAL COMPOSITION IN LAKE ERIE." Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1461444253.
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Basile, Daniela Rodrigues Silva [UNESP]. "Ecotoxicidade e eficácia de sanitizante na redução de Aeromonas hydrophila na água de cultivo e pele de Oreochromus niloticus." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/94613.
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basile_drs_me_jabo.pdf: 758354 bytes, checksum: a2a046dd21b1f6d30060647b68f603d7 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O objetivo do estudo foi determinar a toxicidade aguda do sanitizante (composto por glutaraldeído e cloreto de dimetil cocobenzil amônio) para tilápias (Oreochromis niloticus) e verificar a eficácia do produto utilizado na redução da população de bactérias do gênero Aeromonas presentes na pele dos peixes e na água de criação por contaminação experimental. Para os testes de toxicidade aguda, os animais foram expostos a 0,01, 0,02, 0,03 e 0,04 mL.L-1 e um grupo controle. O produto foi classificado pela toxicidade aguda e pelo risco ambiental de acordo com as classes de valores da CL50;48 horas. Foram realizados testes de ajuste de dose do produto e determinação do limite de tempo de exposição em condições de campo. Para o teste de eficácia os peixes foram expostos a três concentrações do produto (0,01; 0,02 e 0,03 mL.L-1 ) e um grupo testemunha nos seguintes tempos de exposição: zero, 20, 40 e 60 minutos. Amostras de água e pele dos animais foram coletadas ao final de cada tempo de exposição e submetidas às analises microbiológicas. A CL50;48h do produto foi de 0,02 mL.L-1 e esta dose apresenta baixo risco de intoxicação ambiental para a tilápia (O.niloticus). A utilização do produto como sanitizante de peixes foi mais eficaz na redução da população de A. hydrophila da pele do peixe do que na água de criação e quando utilizado na concentração 0,03 mL.L-1 ou 0,02 mL.L-1 por 60 minutos de exposição reduziu quase 1,5 log UFC.mL-1 na pele dos peixes
The aim of this study was determined to assess the acute toxicity of a sanitizer based on glutaraldehyde and cocobenzil dimethyl ammonium chloride compounds for tilapia (Oreochromis niloticus) and verify the effectiveness of the product used in the fish farm water on the reduction of the bacteria population of Aeromonas hydrophila presents on the skin of fish by experimental contamination. For acute toxicity tests, the animals were exposed to 0.01, 0.02, 0.03 and 0.04 mL.L-1 of the tested product and a control group. The product was classified according the acute toxicity and the assessment risk classes. Tests were performed for dose adjustment of the product and determining the limit of exposure time under field conditions for fish weighing between 25 and 60 g and 150 and 200 g. This dose adjustment was based on checking the signs of intoxication of the animals during the exposure time to the product. To the effectiveness test, fish were exposed to three concentrations of the product (0.01, 0.02 and 0.03 mL.L-1) and a control group (without administration of the product) in the following exposure times: zero, 20, 40 and 60 minutes. Water and skin samples were collected at the end of each exposure time and subjected to microbiological analysis. The LC50;48h estimated of the product was 0.02 mL.L-1 and it has been classified as extremely toxic and has a low risk of environmental poisoning tilapia (O.niloticus) when its concentrations is used. The use of concentrations 0.01, 0.02 and 0.03 mL.L-1 for 60 minutes of exposure is considered safe for tilapia, regardless of the fish size. The use of this product as a fish sanitizer was more effective in reducing the population of A. hydrophila on the skin of the fish than in water when used in the water. The concentration 0.03 mL.L-1 or 0.02 mL.L-1 for 60 minutes of exposure reduced by almost 1.5 log UFC.mL-1 in skin of fish
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Basile, Daniela Rodrigues Silva. "Ecotoxicidade e eficácia de sanitizante na redução de Aeromonas hydrophila na água de cultivo e pele de Oreochromus niloticus /." Jaboticabal, 2011. http://hdl.handle.net/11449/94613.
Full textAbstract:
Orientador: Oswaldo Durival Rossi JuniorCoorientador: Claudinei da Cruz
Banca: Luiz Augusto do Amaral
Banca: Leticia Ane Sizuki Nociti
Resumo: O objetivo do estudo foi determinar a toxicidade aguda do sanitizante (composto por glutaraldeído e cloreto de dimetil cocobenzil amônio) para tilápias (Oreochromis niloticus) e verificar a eficácia do produto utilizado na redução da população de bactérias do gênero Aeromonas presentes na pele dos peixes e na água de criação por contaminação experimental. Para os testes de toxicidade aguda, os animais foram expostos a 0,01, 0,02, 0,03 e 0,04 mL.L-1 e um grupo controle. O produto foi classificado pela toxicidade aguda e pelo risco ambiental de acordo com as classes de valores da CL50;48 horas. Foram realizados testes de ajuste de dose do produto e determinação do limite de tempo de exposição em condições de campo. Para o teste de eficácia os peixes foram expostos a três concentrações do produto (0,01; 0,02 e 0,03 mL.L-1 ) e um grupo testemunha nos seguintes tempos de exposição: zero, 20, 40 e 60 minutos. Amostras de água e pele dos animais foram coletadas ao final de cada tempo de exposição e submetidas às analises microbiológicas. A CL50;48h do produto foi de 0,02 mL.L-1 e esta dose apresenta baixo risco de intoxicação ambiental para a tilápia (O.niloticus). A utilização do produto como sanitizante de peixes foi mais eficaz na redução da população de A. hydrophila da pele do peixe do que na água de criação e quando utilizado na concentração 0,03 mL.L-1 ou 0,02 mL.L-1 por 60 minutos de exposição reduziu quase 1,5 log UFC.mL-1 na pele dos peixes
Abstract: The aim of this study was determined to assess the acute toxicity of a sanitizer based on glutaraldehyde and cocobenzil dimethyl ammonium chloride compounds for tilapia (Oreochromis niloticus) and verify the effectiveness of the product used in the fish farm water on the reduction of the bacteria population of Aeromonas hydrophila presents on the skin of fish by experimental contamination. For acute toxicity tests, the animals were exposed to 0.01, 0.02, 0.03 and 0.04 mL.L-1 of the tested product and a control group. The product was classified according the acute toxicity and the assessment risk classes. Tests were performed for dose adjustment of the product and determining the limit of exposure time under field conditions for fish weighing between 25 and 60 g and 150 and 200 g. This dose adjustment was based on checking the signs of intoxication of the animals during the exposure time to the product. To the effectiveness test, fish were exposed to three concentrations of the product (0.01, 0.02 and 0.03 mL.L-1) and a control group (without administration of the product) in the following exposure times: zero, 20, 40 and 60 minutes. Water and skin samples were collected at the end of each exposure time and subjected to microbiological analysis. The LC50;48h estimated of the product was 0.02 mL.L-1 and it has been classified as extremely toxic and has a low risk of environmental poisoning tilapia (O.niloticus) when its concentrations is used. The use of concentrations 0.01, 0.02 and 0.03 mL.L-1 for 60 minutes of exposure is considered safe for tilapia, regardless of the fish size. The use of this product as a fish sanitizer was more effective in reducing the population of A. hydrophila on the skin of the fish than in water when used in the water. The concentration 0.03 mL.L-1 or 0.02 mL.L-1 for 60 minutes of exposure reduced by almost 1.5 log UFC.mL-1 in skin of fish
Mestre
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Franceschini, Lidiane [UNESP]. "Infecções parasitárias e microbianas na produção do pacu Piaractus mesopotamicus e do híbrido patinga procedentes da região noroeste do Estado de São Paulo." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/99444.
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franceschini_l_me_botib.pdf: 588829 bytes, checksum: 796cb08752fb62d3915ad06ac0d6aa82 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O desenvolvimento das atividades relacionadas à aquicultura tem aumentado consideravelmente a relevância dos estudos sobre parasitas e outros patógenos de organismos aquáticos, principalmente, daqueles hospedeiros com potencial para o cultivo e comercialização. O objetivo deste estudo foi avaliar a ocorrência de infecções parasitárias e microbianas na produção de pacu Piaractus mesopotamicus e do híbrido patinga (P. mesopotamicus x Piaractus brachypomus) procedentes da região Noroeste do Estado de São Paulo, Brasil. Três pisciculturas foram amostradas bimestralmente, de fevereiro de 2010 a fevereiro de 2011: A - Reprodução e Larvicultura (pacu/patinga), B - Engorda (patinga) e C - Pesque-pague (pacu/patinga), das quais 35 peixes foram submetidos à análise parasitológica e 21 à análise microbiológica. Foram encontrados os parasitas: dactilogirídeos (Monogenea); Trichodina spp., Ichthyophthirius multifiliis, Chilodonella sp. (Protozoa); Myxobolus spp. e Henneguya spp. (Myxozoa); Rondonia rondoni e Contracaecum sp. (Nematoda); e Dolops carvalhoi (Crustacea). Dentre os peixes analisados, 62,9% de “A” e 100% de “B” e “C” estavam infectados/infestados por pelo menos uma espécie de parasita. Pacus (n=44) apresentaram maior suscetibilidade a infestações por Anacanthorus penilabiatus, e as patingas (n=61), por Mymarothecium viatorum (p<0,05). Na análise microbiológica, 23,8% dos peixes de “A” e “B” e 33,3% da propriedade “C” estavam infectados com pelo menos um gênero de bactéria. A sazonalidade influenciou as infestações por Trichodina spp., A. penilabiatus e infecções pela bactéria Enterobacter sp. em patingas (p<0,05). No antibiograma, cepas de Pseudomonas sp., Stenotrophomonas maltophilia e Aeromonas sp. apresentaram resistência a todos antibióticos...
The development of activities related to aquaculture has considerably increased the relevance of studies on parasites and other pathogens of aquatic organisms, especially those with potential for production and marketing. The aim of this study was to evaluate the occurrence of parasitic and microbial infections in the “pacu” Piaractus mesopotamicus and hybrid patinga (P. mesopotamicus x Piaractus brachypomus) from the Northwest of São Paulo State, Brazil. Fishes from three fish farms were evaluated every two months: A - Reproduction and larviculture (pacu / patinga), B - Growout (patinga) and C - Fee-fishing property (pacu / patinga). Fishes from each fish farm were collected from February 2010 to February 2011 for parasitological (n = 35 per property) and microbiological (n = 21 per property) analysis. The parasites found were: Dactylogyridae (Monogenea), Trichodina spp., Ichthyophthirius multifiliis, Chilodonella sp. (Protozoa), Myxobolus spp., Henneguya spp. (Myxozoa), Rondonia rondonia, third stage larvae of Contracaecum sp. (Nematoda), and Dolops carvalhoi (Crustacea). Among the fishes examined, 62.9% from A and 100% from B and C were infected / infested with at least one parasite species. Pacu (n = 44) showed higher susceptibility to infestations caused by Anacanthorus penilabiatus and patinga (n = 61) by Mymarothecium viatorum (p < 0.05). In the microbiological analysis, 23.8% of fishes from A and B properties and 33.3% of fish from the property C were infected with at least one bacteria species. Seasonality influenced Trichodina spp. and A. penilabiatus infestations and infection caused by Enterobacter sp. in patingas (p < 0.05). In antibiogram test, strains of Pseudomonas sp., Stenotrophomonas maltophilia and Aeromonas sp. were resistant to all beta-lactam antibiotics... (Complete abstract click electronic access below)
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Franceschini, Lidiane. "Infecções parasitárias e microbianas na produção do pacu Piaractus mesopotamicus e do híbrido patinga procedentes da região noroeste do Estado de São Paulo /." Botucatu : [s.n.], 2012. http://hdl.handle.net/11449/99444.
Full textAbstract:
Orientador: Reinaldo José da SilvaCoorientador: Sérgio Henrique Canello Schalch
Banca: Eduardo Makoto Onaka
Banca: Maurício Laterça Martins
Resumo: O desenvolvimento das atividades relacionadas à aquicultura tem aumentado consideravelmente a relevância dos estudos sobre parasitas e outros patógenos de organismos aquáticos, principalmente, daqueles hospedeiros com potencial para o cultivo e comercialização. O objetivo deste estudo foi avaliar a ocorrência de infecções parasitárias e microbianas na produção de pacu Piaractus mesopotamicus e do híbrido "patinga" (P. mesopotamicus x Piaractus brachypomus) procedentes da região Noroeste do Estado de São Paulo, Brasil. Três pisciculturas foram amostradas bimestralmente, de fevereiro de 2010 a fevereiro de 2011: A - Reprodução e Larvicultura (pacu/patinga), B - Engorda (patinga) e C - Pesque-pague (pacu/patinga), das quais 35 peixes foram submetidos à análise parasitológica e 21 à análise microbiológica. Foram encontrados os parasitas: dactilogirídeos (Monogenea); Trichodina spp., Ichthyophthirius multifiliis, Chilodonella sp. (Protozoa); Myxobolus spp. e Henneguya spp. (Myxozoa); Rondonia rondoni e Contracaecum sp. (Nematoda); e Dolops carvalhoi (Crustacea). Dentre os peixes analisados, 62,9% de "A" e 100% de "B" e "C" estavam infectados/infestados por pelo menos uma espécie de parasita. Pacus (n=44) apresentaram maior suscetibilidade a infestações por Anacanthorus penilabiatus, e as patingas (n=61), por Mymarothecium viatorum (p<0,05). Na análise microbiológica, 23,8% dos peixes de "A" e "B" e 33,3% da propriedade "C" estavam infectados com pelo menos um gênero de bactéria. A sazonalidade influenciou as infestações por Trichodina spp., A. penilabiatus e infecções pela bactéria Enterobacter sp. em patingas (p<0,05). No antibiograma, cepas de Pseudomonas sp., Stenotrophomonas maltophilia e Aeromonas sp. apresentaram resistência a todos antibióticos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The development of activities related to aquaculture has considerably increased the relevance of studies on parasites and other pathogens of aquatic organisms, especially those with potential for production and marketing. The aim of this study was to evaluate the occurrence of parasitic and microbial infections in the "pacu" Piaractus mesopotamicus and hybrid "patinga" (P. mesopotamicus x Piaractus brachypomus) from the Northwest of São Paulo State, Brazil. Fishes from three fish farms were evaluated every two months: A - Reproduction and larviculture (pacu / patinga), B - Growout (patinga) and C - Fee-fishing property (pacu / patinga). Fishes from each fish farm were collected from February 2010 to February 2011 for parasitological (n = 35 per property) and microbiological (n = 21 per property) analysis. The parasites found were: Dactylogyridae (Monogenea), Trichodina spp., Ichthyophthirius multifiliis, Chilodonella sp. (Protozoa), Myxobolus spp., Henneguya spp. (Myxozoa), Rondonia rondonia, third stage larvae of Contracaecum sp. (Nematoda), and Dolops carvalhoi (Crustacea). Among the fishes examined, 62.9% from "A" and 100% from "B" and "C" were infected / infested with at least one parasite species. Pacu (n = 44) showed higher susceptibility to infestations caused by Anacanthorus penilabiatus and patinga (n = 61) by Mymarothecium viatorum (p < 0.05). In the microbiological analysis, 23.8% of fishes from "A" and "B" properties and 33.3% of fish from the property "C" were infected with at least one bacteria species. Seasonality influenced Trichodina spp. and A. penilabiatus infestations and infection caused by Enterobacter sp. in patingas (p < 0.05). In antibiogram test, strains of Pseudomonas sp., Stenotrophomonas maltophilia and Aeromonas sp. were resistant to all beta-lactam antibiotics... (Complete abstract click electronic access below)
Mestre
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Hispano, Vilaseca Coral. "Avaluació d'una infestació de Gnathia maxillaris (Montagu, 1804) (Crustacea:Isopoda:Gnathiidae), a partir del seguiment i eradicació d'un brot a un sistema d'aquaris de grans dimensions." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/385111.
Full textAbstract:
Gnathia maxillaris és un isòpode marí ectoparàsit hematòfag de peixos. Diferents brots d’infestacions han estat descrits en animals salvatges i més recentment en sistemes de producció de l’aqüicultura o en tancs d’exhibició d’aquaris. El control d’aquests brots o l’aplicació de mesures o programes d’eradicació resulten molt complexos degut a que el seu cicle biològic ha estat només parcialment descrit, no es disposa d’un coneixement detallat sobre l’ecologia de l’espècie i no existeix informació sòlida sobre tractaments terapèutics o preventius específics per aquesta parasitosi. En aquest treball es segueix el desenvolupament d’una infestació de Gnathia maxillaris en un aquari de gran volum. Per tal d’avaluar el grau d’infestació del sistema es va desenvolupar un mètode que permetés conèixer quina era la dinàmica de la població del paràsit i l’eficiència de les actuacions realitzades per controlar-lo la infestació en el sistema. Aquest mètode consistia en realitzar un mostreig freqüent en el tanc, no només a nivell quantitatiu sinó que es diferenciaven els individus segons el seu estadi larvari. En l’estudi també s’ha avaluat l’eficiència del tractament de la parasitosi amb triclorfon, al mateix temps es va estudiar la cinètica de degradació del triclorfon al llarg de la seva aplicació. Disposar d’exemplars de larves d’aquesta espècie ha permès desenvolupar un sistema pel manteniment dels diferents estadis del paràsit al laboratori. A més a més, aquest sistema de manteniment ha facilitat que es desenvolupés en condicions de laboratori el cicle biològic, i així permetre el seu estudi. S’ha complementat la descripció del cicle de vida de G.maxillaris fet per Mouchet (1928) i s’ha aportat informació per entendre les dinàmiques del paràsit en el tanc afectat. A l’hora s’ha realitzat una descripció del mascle amb l’ajut del microscopi electrònic que ha permès complementar la descripció de l’espècie realitzada per Monod (1926). El manteniment de larves al laboratori i la possibilitat de desenvolupar el cicle ens ha permès avaluar el grau d’eficiència de productes quimioterapèutics alternatius que s’han aplicat a nivell d’aqüicultura per combatre sea lice en cultius de salmó (Salmo salar). L’objectiu pràctic d’aquest treball ha estat eradicar la Gnathia maxillaris del sistema mediterrani afectat de l’Aquàrium i ha permès que cada un dels estudis realitzats han ajudat a adquirir nous coneixements sobre G.maxillaris i sobre com controlar una infestació en aquaris de gran volum i de gran complexitat en la gestió de les aigües i les poblacions d’animals.Gnathia maxillaris is a haematophagous isopoda ectoparasite that feed on the blood and tissue fluids of marine fish. Several outbreaks of infestations have been described in wild animals and more recently aquaculture production systems or in tanks of aquaria. The control of these outbreaks or measures for eradication are very complex due to its biological cycle has been only partially described, to a limited knowledge about the ecology of this species and to the lack of solid information on specific preventive or therapeutic treatment. This study monitored the development of an infestation Gnathia maxillaris in a large volume aquarium. In order to assess the degree of infestation, a method for monitoring the development of the outbreaks was defined. It allowed to know the population dynamics of the parasite and to assess the efficiency of the applied actions to control the infestation in the system. The monitoring was based on practical daily sampling of the affected tank to quantify the number of larvi and to determine the proportions of the parasite at the different larval stages of its life cycle.. Additionally, it was evaluated the efficiency of the trichlorfon as treatment to control this type of crustacean infestation. The kinetics of decay of this compound after application in the water tank were also determined.. The availability of larvi from the affected tank allowed to define a methodology for maintenance in vivo at the laboratory and facilitate to follow the life cycle.The obtained observations are complementary new contributions to the first description of the life cycle by Mouchet (1928). Moreover, it provided practical and useful information to understand the dynamics of G.maxillaris in the infested tank. The scanning electronic microscopy studies of males obtained in this outbreak aided to supplement the morphological and biometric description of this species made by Monod (1926). The maintenance of larvi in the laboratory and the possibility of developing its life cycle at the laboratory in vivo allowed assessing the efficiency of some potential chemotherapeutic compounds that have been already applied in aquaculture against sea lice in cultured salmon (Salmo salar). The practical application of the results of this study was to eradicate G.maxillaris from the infested Mediterranean aquaria. Every performed study contribute with new knowledge on G.maxillaris biology and ecology, and provided practical information to control and eradicate this parasite from a large volume and complex biological system in terms of diversity and concentration of aquatic organism.
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Williamson, Heather. "Distribution of Mycobacterium ulcerans in Aquatic Environments in Ghana." 2008. http://etd.utk.edu/2008/August2008Dissertations/WilliamsonHeatherRose.pdf.
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Ward, Christopher Spencer. "Microbial Community Responses to Natural and Anthropogenic Disturbances in Aquatic Ecosystems." Diss., 2015. http://hdl.handle.net/10161/11354.
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Aquatic ecosystems are highly dynamic environments, suggesting that resident microbial communities to respond and adapt to these environmental changes. However, despite the frequency of disturbances in aquatic ecosystems such as annual cycles in environmental parameters and episodic storm events, few studies have examined the impacts of disturbances on aquatic microbial communities. In this dissertation, I investigate community- and taxon-level responses to natural and anthropogenic disturbances in the coastal ocean and wetland mesocosms using ribosomal RNA gene library sequencing. In my first chapter, I present an overview on disturbances in microbial communities and describe microbial interaction network-based approaches for predicting disturbance effects. In my second chapter, I use three years of weekly coastal ocean samples to identify transitions between distinct summer- and winter-associated taxa that occur across the microbial community over relatively short time intervals. Using the same time series, I find that episodic disturbances involve in rapid turnover of both abundant and conditionally rare taxa depending on environmental conditions and initial community composition. Finally, I investigate the microbial responses to acute and chronic environmental loading of an emerging contaminant in replicated wetland mesocosms. Despite the antimicrobial properties of silver nanoparticles, community changes in both treatments appear to be dominated by indirect effects through aquatic plant die-off, though the timing, duration, and magnitude of responses vary. Together, my dissertation demonstrates that associations between microbial taxa, environmental factors, and other components of the ecosystem all contribute to community response to disturbance. By exploring community responses to disturbance, new insights can be gained into the resistance and resilience of microbial communities in response to environmental drivers of community change.
Dissertation
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Stout, Lisa M. "Influence of plant-associated microbial communities on heavy metal uptake by the aquatic plant Lemna minor." 2006. https://scholarworks.umass.edu/dissertations/AAI3242356.
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We present research aimed at determining how bacteria associated with aquatic plants influence phytoextraction of heavy metals. We focused on the aquatic plant Lemna minor and its response to cadmium (Cd) as a model. We studied bacterial communities from plants at a contaminated site, Rice City Pond (RCP), and plants provided by the U.S. Environmental Protection Agency (EPA) that had not been exposed to Cd. Initially, we performed comparative studies of the bacterial communities from these plants, with or without Cd addition, by analysis of 16S rRNA genes. We also studied Cd tolerance in both bacteria and plants in this system. Bacterial isolates were screened for metal tolerance and for the presence of Cd resistance genes, and we compared plant resposes to Cd between surface sterilized plants and plants with associated bacterial communities. In order to further determine the effects of bacteria on plants, sterile plants inoculated with bacterial isolates were grown in medium to enrich for bacterial growth. We measured plant growth rate, root length, final medium pH, bacterial biomass, and Cd concentrations in plants. We determined through 16S rRNA analyses that both EPA and RCP plants supported diverse bacterial communities. Upon Cd addition, EPA and RCP communities showed similar shifts in diversity, both becoming more diverse upon Cd addition. When investigating isolates from these treatments, we found that exposure to Cd increased culturability on Cd-amended medium; however, increased metal tolerance was not seen in all or even most isolates from treatments with Cd exposure, and Cd resistance systems were only found in a few isolates. We saw that surface-sterilized plants accumulated slightly higher concentrations of Cd than non-sterile plants. When enriched, bacteria slightly lowered the pH of the medium, but strong effects on root elongation and Cd phytoextraction. Bacteria seem to influence root elongation positively and influence Cd uptake negatively, keeping toxic concentrations of the metal from entering the plant. This study will allow better understanding of the role of aquatic plant-associated microbial communities in phytoremediation of heavy metals.
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Hipsey, Matthew Richard. "Dynamics of microbial pollution in aquatic systems." 2007. http://hdl.handle.net/2440/37890.
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Microbial pollution of surface waters and coastal zones is one of the foremost challenges facing the water industry and regulatory authorities. Yet despite the concern and increasing pressures on water resources in both developed and developing countries, understanding of microbial pollutants in the aquatic environment is fairly scattered. There is a need for an improved ability to quantify the processes that control the fate and distribution of enteric organisms to support decision - making and risk management activities. The aim of this thesis has been to advance the understanding of the dynamics of microbial pollution in aquatic systems through review, experimentation and numerical modelling. Initially, a new module for simulating the protozoan pathogen, Cryptosporidium, was developed and implemented within a three - dimensional ( 3D ) coupled hydrodynamic - water quality model ( ELCOMCAEDYM ). The coupled 3D model was validated against a comprehensive dataset collected in Myponga Reservoir ( South Australia ), and without calibration, performed to a high degree of accuracy. The investigation then sought to examine the experimental dataset in more detail and found a significant difference between protozoan pathogens and the bacterial and viral indicators. To examine the role of bacterial association with particles in more detail, a second experimental campaign was carried out in Sugarloaf Reservoir ( Victoria ). This campaign was used to gain insights into the association of coliform bacteria with suspended sediment and to quantify their sedimentation dynamics based on in situ measurements. Using an inverse technique, particle profile data was used to create a simple Lagrangian model that was applied to back - calculate the sedimentation rates of the coliform bacteria and the fraction that were attached to the particles. The results indicated that 80 - 100 % were associated with a small - sized clay fraction. This result was in contrast with the Cryptosporidium dynamics in Myponga Reservoir, where it was concluded that oocysts did not settle with the inorganic particles. These findings indicated the current models for simulating the array of organisms of interest to regulatory authorities are inadequate to resolve the level of detail necessary for useful predictions and risk management. Large differences between the protozoa, bacteria and phages were being observed due to different particle association rates and sedimentation dynamics, order of magnitude differences in natural mortality rates, and different sensitivity to sunlight bandwidths. The original model implemented within CAEDYM was therefore rewritten to be more complete and generic for all microbial pollutants and different types of aquatic systems. The model was built using a generic set of parameterizations that describe the dynamics of most protozoan, bacterial and viral organisms of interest. The parameterizations dynamically account for sensitivities to environmental conditions, including temperature, salinity, pH, dissolved oxygen, sunlight, nutrients and turbidity, on the growth and mortality of enteric organisms. The new model significantly advances previous studies in several areas. First, inclusion of the growth term allows for simulation of organisms in warm, nutrient rich environments, where typical die - off models tend to over - predict loss rates. Second, the natural mortality term has been extended to independently account for the effects of salinity and pH, in addition to temperature. The salinity - mediated mortality has also been adapted to account for the nutrient status of the medium to simulate the importance of nutrient starvation on the ability of an organism to survive under osmotic stress. Third, a new model for sunlight - mediated mortality is presented that differentially accounts for mortality induced through exposure to visible, UV - A and UV - B bandwidths. The new expression has capacity to simulate the photo - oxidative and photo - biological mechanisms of inactivation through included sensitivities to dissolved oxygen and pH. Fourth, the model allows for organisms to be split between free and attached pools, and sedimented organisms may become resuspended in response to high shear stress events at the water - sediment interface caused by high velocities or wind - wave action. Fifth, the enteric organism module has been implemented within the bio - geochemical model CAEDYM, thereby giving it access to dynamically calculated concentrations of dissolved oxygen, organic carbon, and suspended solids, in addition to pH, shear stress and light climate information. Without adjustment of the literature derived parameter values, the new model was validated against a range of microbial data from three reservoirs that differed in their climatic zone, trophic status and operation. The simulations in conjunction with the experimental data highlighted the large spatial and temporal variability in processes that control the fate and distribution of enteric organisms. Additionally, large differences between species originate from variable rates of growth, mortality and sedimentation and it is emphasized that the use of surrogates for quantifying risk is problematic. The model can be used to help design targeted monitoring programs, examine differences between species and the appropriateness of surrogate indicators, and to support management and real - time decision - making. Areas where insufficient data and understanding exist are also discussed.Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2007.