The quorum sensing signaling system based on intercellular exchange of N-acyl-homoserine lactones is used by many proteobacteria to regulate the transcription of essential genes in a signal density-dependent manner. It is involved in a number of processes including the development of highly organized bacterial communities, e.g., biofilms, the regulation of expression of virulence factors, production of antibiotics, and bioluminescence. The extensive genetic and biochemical data available on the quorum sensing system in Vibrio fischeri allows the development of a systems biology approach to undertake a spatial and dynamical analysis of the regulation throughout the population. The quorum sensing regulated lux genes are organized in two divergent transcriptional units: luxR and luxICDABEG. The latter contains the genes required for luminescence and the luxI gene necessary for synthesis of an N-acyl-homoserine lactone commonly called autoinducer (AI). The luxR gene codes for a transcriptional regulatory protein that activates the transcription of both operons at a threshold concentration of AI. The positive feedback loop induces a rapid increase of transcription level of the lux genes when a critical population density is reached (reflected by the concentration of AI in the environment). With a combination of molecular biology tools, physiological analysis, and mathematical modeling we identified critical characteristics of the system and expect to assign parameter values in order to achieve a comprehensive understanding of the dynamics. An ordinary differential equation mathematical model is used to investigate the dynamics of the system and derive parameter values. In parallel a novel microfluidic cell culture experimental set-up is used to carefully control environmental parameters as well as to achieve chemostatic conditions for high-density cell populations. An unstable variant of the green fluorescent protein was used as a reporter to follow the time response at a single cell level. Thus spatial organization and noise across the population can be analyzed. Plasmids carrying different genetic constructs were transformed in a recombinant Escherichia coli strain to specifically identify genetic and biochemical elements involved in the regulation of the lux genes under diverse conditions. Then the quantitative data extracted from batch culture and microfluidic assays were used to assign parameter values in the models. The particular question being investigated first is the nature of the regulation to increasing concentration of the signal. The hypothesis tested is that the regulation of the production of the signal by individual cells is biphasic and, therefore, quorum sensing should be robust to global and local variations in cell density. / Master of Science

Plus de 130 espèces de Vibrio, bactéries ubiquitaires des milieux marins et estuariens sont décrites, dont certaines sont des pathogènes d’organismes marins (poissons, coraux, coquillages, …). Douze espèces sont pathogènes pour l’homme, parmi lesquelles V. cholerae, V. parahaemolyticus et V. vulnificus. Les cas d’infections humaines sont essentiellement liés à la consommation de produits de la mer crus ou à l’exposition de plaies cutanées à l’eau de mer. En France, ce risque est faible mais pourrait s’accentuer en raison de la consommation croissante de produits de la mer, de l'augmentation de la part des individus immunodéprimés dans la population, de l'impact des activités anthropiques et du réchauffement climatique sur le milieu marin. Une meilleure compréhension de l'écologie de ces bactéries (distribution, abondance et diversité) est un pré-requis à la mise en place d’une surveillance environnementale de ce risque. L’étude menée au cours de ma thèse en zone Manche-Mer du Nord, dans le cadre du programme Vibrio Manche (2009-2012, partenariat EDFR&D/Ifremer/Institut Pasteur de Lille), avait pour objectif d'évaluer la diversité et la distribution spatio-temporelle côtière des vibrions, dont des espèces potentiellement pathogènes pour l’homme et les animaux, et leur relation avec les paramètres environnementaux biologiques (phytoplancton et zooplancton) et physico-chimiques. La stratégie de suivi a reposé sur le dénombrement et l’isolement de souches de Vibrio, à 22°C et 37°C sur milieu sélectif, à partir d’eau de mer et de sédiments superficiels collectés au cours de neuf campagnes d’échantillonnage et associés à la mesure de paramètres environnementaux. Le développement et la validation d’outils d’identification des souches environnementales par PCR en temps réel et le séquençage de marqueurs génétiques discriminants ont conduit à mettre en évidence une grande diversité d’espèces parmi les isolats à 22°C, celle-ci étant composée principalement de pathogènes d’organismes marins dont l’espèce V. splendidus. Les isolats à 37°C, marqués par la prédominance de deux espèces, V. alginolyticus et V. harveyi, et la rareté des pathogènes humains détectés dans les conditions d’analyses retenues pour cette étude. Au terme de l’étude, nous avons mis en évidence la présence de 20 et 17 espèces de vibrions respectivement à 22°C (deux campagnes) et 37°C (neuf campagnes) sur la zone étudiée, et l’influence probable de conditions environnementales contrastées sur la structure de ces populations. En termes d’abondance, les vibrions cultivables à 37°C ont montré une forte saisonnalité, et une relation significative à la température de l’eau et à l’abondance totale du zooplancton. La saisonnalité des vibrions cultivables à 22°C a été moindre, et leur abondance a pu être reliée de façon significative à la concentration en chlorophylle a totale et également à l’abondance totale en zooplancton. Ces éléments de connaissance et la stratégie d’identification développée pourront, à terme, contribuer au développement d’outils de surveillance microbiologique environnementale et ouvrent des perspectives pour mieux comprendre l’écologie des vibrions et les facteurs structurant non seulement leur abondance, mais aussi leur diversité. / One hundred and thirty species of vibrios, ubiquitous bacteria of marine and estuarine environments have been described, some of them being pathogenic for marine organisms. Twelve species are classified as human pathogens, Vibrio cholerae, V. parahaemolyticus and V. vulnificus being the most frequently reported in cases of infection. Human infections are linked mostly to raw seafood consumption or to the exposure of skin wounds to contaminated seawater. In France, the risk is low but it is expected to increase in the future due to the increase of raw seafood consumption, the part of immuno-compromised people, but also the impact of anthropic activities and global warming on the marine environment. A better understanding of the ecology of these bacteria (distribution pattern, abundance and diversity) is a prerequisite for the monitoring of the Vibrio-risk in the environment. The 2-year study carried out in the Eastern English Channel during my PhD was part of the Vibrio Manche program (2009-2012, funding EDF R&D/Ifremer/Institut Pasteur de Lille), which main objective was to characterize the spatio-temporal distribution of the vibrios, among which the potentially pathogenic species for human and animal, and their relations with the biotic(phytoplankton and zooplankton) and abiotic environmental parameters. The strategy consisted in the enumeration and isolation of Vibrio strains, at 22°C and37°C on a selective medium, from seawater and superficial sediments collected during nine sampling campaigns and associated with the recording of environmental parameters. The protocol developed in this study provides an appropriate and rapid screening tool to identify a large number of bacterial strains routinely isolated from the environment. This was based on real-time PCR assays and the sequencing of discriminant genetic markers. We highlighted the important diversity of species among the 22°C isolates, represented mainly by species pathogenic for marine organisms such as V. splendidus. Contrastingly, the 37°C isolates were mainly represented by two species, V. alginolyticus and V. harveyi, and the potentially pathogenic species for humans were rarely detected using this experimental approach. We detected 20 and 17 species of vibrios among the 22°C (two sampling campaigns) and 37°C(nine sampling campaigns) isolates, respectively, and highlighted the probable influence of contrasted environmental conditions on these populations structure. These two populations presented different seasonal dynamics, as the seawater temperature and the zooplankton abundance showed to be the main drivers for the 37°C population. The 22°C population seemed to be linked to the chlorophyll a concentration and zooplankton abundance. These data and the approach developed in this study could contribute to the development of tools for the monitoring of coastal environment and they give perspectives to better understand the ecology of the vibrios and the environmental factors driving their abundance and diversity.

Práticas nutricionais saudáveis e a globalização cultural popularizaram o consumo de pratos à base de peixe cru, anteriormente restritos aos países orientais. Estimativas mostram que doenças de origem alimentar causam aproximadamente 76 milhões de casos, 325 mil hospitalizações e 5 mil mortes a cada ano, somente nos Estados Unidos. Casos com etiologia desconhecida somam 62 milhões, com 265 mil hospitalizações e 3.200 mortes. O objetivo deste estudo foi investigar a presença de Escherichia coli, Salmonella spp. e Staphylococcus aureus e cepas potencialmente patogênicas de Aeromonas spp. e Vibrio spp. em peixes comercializados em feiras livres da cidade de São Paulo, Brasil. Vinte amostras de peixes, de diferentes espécies, foram adquiridas em feiras livres e analisadas utilizando metodologia convencional para investigação de patógenos em alimentos. Altos níveis de contaminação fecal foram detectados em 25% das amostras. Staphylococcus aureus foi isolado em 10% das amostras, entretanto em valores abaixo do permitido pela legislação brasileira. Todas as amostras estavam negativas para Salmonella spp. V. parahaemolyticus não foi isolado, 30% das amostras foram positivas para outras espécies de Vibrio, inclusive Vibrio cholerae não-O1/não-O139. Aeromonas spp. , incluindo A. hydrophila foi isolada em 50% das amostras de peixe. O isolamento de Vibrio cholerae não-O1/não-O139 e Aeromonas hydrophila, assim como Staphylococcus aureus e Escherichia coli, sugere que peixes comercializados em feiras livres da cidade de São Paulo podem representar um risco para os consumidores e ser um importante veículo de transmissão de espécies enteropatogênicas. / Healthier nutritional lifestyles and cultural globalization have popularized the consumption of raw fish dishes that were previously restricted to oriental countries. Estimates indicate that food-borne diseases cause approximately 76 million illnesses, 325,000 hospitalizations and 5,000 deaths each year in the United States alone. Cases with unknown etiology account for 62 million illnesses, 265,000 hospitalizations and 3,200 deaths. The purpose of this study was to investigate the presence of Escherichia coli, Salmonella spp., Staphylococcus aureus and potentially pathogenic strains of Aeromonas spp. and Vibrio spp. in fish commercialized at the retail level in the markets of São Paulo City, Brazil. Twenty fish of different species were analysed for foodborne pathogens using conventional methodologies. High levels of faecal contamination were detected in 25% of fish samples. Staphylococcus aureus was isolated from 10% of samples; however, in each case this was below the limits established by Brazilian legislation. All samples were negative for Salmonella and 30% tested positive for others Vibrio spp., including Vibrio cholerae non-O1/non-O139. Vibrio parahaemolyticus was not found in this study. Aeromonas spp., including A. hydrophila, were isolated in 50% of fish samples. The isolation of Vibrio cholerae non-O1/non-O139 and Aeromonas hydrophila as well as Staphylococcus aureus and Escherichia coli suggests that fish commercialized in São Paulo City may represent a health risk to consumers and be an important vehicle for transmission of these enteropathogenic species.

A cidade de Jundiaí está localizada a aproximadamente 60 Km de São Paulo e tem uma população de 342.983 mil habitantes sendo que 94,37% residem na zona urbana. A cidade está inserida na bacia hidrográfica do Rio Jundiaí, rio que é formado a partir da confluência do Rio Jundiaizinho com o Ribeirão das Taipas e possui uma extensão de 123 quilômetros e sua foz está situada em Salto, na confluência do Rio Jundiaí com o Rio Tietê. Está é menor bacia hidrográfica do estado de São Paulo e também uma das mais industrializadas. A cidade de Jundiaí conta com a Estação de Tratamento de Esgotos Novo Horizonte (ETE Jundiaí), que coleta 98% dos esgotos da cidade, trata 100% de todo esgoto coletado, com eficiência de remoção de 92% de carga orgânica, esgoto que depois do tratamento é lançado no Rio Jundiaí. O objetivo deste trabalho foi utilizar ensaios de toxicidade com organismos aquáticos para avaliar a carga tóxica que chega à ETE, bem como a eficiência do tratamento biológico e a influência da estação no seu entorno. Foram coletadas amostras em 6 pontos distintos; à montante da ETE (P1), na entrada da ETE (P2), na calha de distribuição das lagoas de aeração (P3), nas 2 saídas da ETE (P4 e P5) e à jusante da ETE (P6). As amostras de afluente da ETE foram mais tóxicas que os efluentes da ETE; já os resultados das amostras do rio não apresentaram diferença. Para Vibrio fischeri os valores de CE(i)50 variaram entre 2,23% e 9,39% para a calha de entrada das lagoas de aeração, enquanto que para Daphnia similis variaram entre 15,52% e 89,95%; para a entrada da ETE os valores variaram entre 4,63% e 8,31% para Vibrio fischeri , e 17,68% e não tóxico para Daphnia similis. Nas campanhas onde foram amostradas as saídas da ETE e águas do rio, os ensaios realizados com Vibrio fischeri apresentaram resultados entre 53,55% e não tóxico para águas do rio e 29,46% e não tóxico para o efluente da ETE, já para Daphnia similis, os resultados estão entre 55,92% e não tóxico para águas do rio e 70,97% e não tóxico para o efluente da ETE. Nos ensaios realizados com Ceriodaphnia dubia, a média de nascimentos para águas do rio esteve entre 4,60 e 15,00 enquanto que para o efluente da ETE esteve entre 4,50 e 10,35 para amostra bruta. Os resultados de toxicidade comprovam a eficiência da ETE na remoção de toxicidade porém outros parâmetros devem ser observados para se comprovar o impacto de seus efluentes sobre as águas do rio. / Jundiaí is located approximately 60 kilometers from São Paulo and has a population of 342,983 habitants which 94.37% lives in urban areas. Jundiaí is included in the Jundiaí River basin witch is formed from the confluence of River Jundiaizinho with Ribeirão das Taipas, it has a length of 123 kilometers and its mouth is located in Salto, at the confluence of Jundiaí River with Tietê River. This is the smaller basin of the state and also one of the most industrialized. Jundiaí has the Novo Horizonte Wastewater Treatment Plant (NHWWP) which collects 98% of the city sewage, and treats 100% of it, with the removal of organic load efficiency 92%, which waste is drainage in Jundiaí River. The present work used toxicity tests with aquatic organisms to assess the toxic effect that comes form the station, the efficiency of biological treatment, and the influence of the station on its surroundings. Samples were collected at 6 different points, the upstream of NHWWP (P1), the entry of NHWWP (P2), in the pipeline for distribution to the aeration lagoons (P3), in the 2 outputs (P4 and P5) and downstream of NHWWP (P6). The samples of the influents were more toxic than the effluent of NHWWP and the results from the river samples did not show difference. The effective toxic concentrations EC 50 ranged between 2.23% and 9.39% for Vibrio fischeri on the pipeline entry to and lagoons, and varied between 15.52% and 89.95% for Daphnia similis, for the NHWWP enter the values ranged between 4.63% and 8.31% for Vibrio fischeri, and 17.68% and not toxic to Daphnia similis. In campaigns where sampled the outputs of NHWWP and river waters, the tests with Vibrio fischeri performed between 53.55% and not toxic to the river water and 29.46% and not toxic to the effluent of NHWWP, for while to Daphnia similis, the results were between 55.92% and not toxic to the river water and 70.97% and not toxic to the effluent of ETE. In tests conducted with Ceriodaphnia dubia, the average of births for the river water was between 4.60 and 15.00 while for the effluent of NHWWP was between 4.50 and 10.35 for crude sample. The results show the efficiency of NHWWP in the removal of toxicity but other parameters should be observed to demonstrate the impact of their effluents on the River waters.

Submitted by (edna.saturno@ufrpe.br) on 2017-02-14T15:03:25Z No. of bitstreams: 1 Joana angelica L V Carvalho.pdf: 451922 bytes, checksum: 66f7ebcb01d8574ab7c4cced0c81dce6 (MD5) / Made available in DSpace on 2017-02-14T15:03:25Z (GMT). No. of bitstreams: 1 Joana angelica L V Carvalho.pdf: 451922 bytes, checksum: 66f7ebcb01d8574ab7c4cced0c81dce6 (MD5) Previous issue date: 2011-02-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study aimed to evaluate the survival of Litopenaeus vannamei shrimp larvae treated with probiotic bacteria and subsequently infected by Vibrio harveyi and Vibrio alginolyticus. Shrimp were kept in two 80L tanks under similar culture conditions, but only one tank was previously treated with commercial probiotic (Bacillus spp.) added daily in the water at a concentration of 105 CFU/ml. This protocol was maintained until the animals reach the stage of development needed for the infection experiments by Vibrio spp. Three independent infection experiments were performed: Zoea1 to Zoea3, Mysis1 to Mysis3 and Postlarvae (PL)10 to PL14 with the following treatments with four replicates each: only V. harveyi; commercial probiotic + V. harveyi; only V. alginolyticus; commercial probiotic + V. alginolyticus; and without Vibrio spp. and probiotic (Control). In the experiment with PL, only the treatments with V. harveyi; commercial probiotic + V. harveyi and control were used. Vibrio species were inoculated only at the beginning of each experiment at a concentration of 107 CFU/ml. At the end of experiments, a sample of water and shrimp from each experimental unit was submitted to quantification of Vibrio spp. Additionally, was realized an antagonism test of Bacillus spp. against Vibrio spp. In the experiments with zoea and mysis, larvae cultured in treatment V. harveyi had a significantly lower survival when compared with treatments V. alginolyticus and control. There was a significant increase in survival of zoea and mysis larvae treated with probiotic + V. harveyi with 81.07 and 90.13%, differentiating the larvae infected only with V. harveyi with 12.80 and 69.13%, respectively. There were no significant differences in survival of postlarvae among treatments. Total Vibrio spp. counts decreased in the water and shrimp of treatments with the use of probiotic. The probiotic (Bacillus spp.) showed inhibitory activity against Vibrio spp. in vitro. The results indicated an increase in the survival of early larval stages (zoea and mysis) infected by V. harveyi after treatment with Bacillus spp. The administration of probiotic bacteria is a promising alternative for the prevention of Vibrio spp. in larviculture of L. vannamei. / O presente estudo teve como objetivo avaliar a sobrevivência de larvas de Litopenaeus vannamei tratadas com bactérias probióticas e posteriormente infectadas por Vibrio harveyi e Vibrio alginolyticus. Os camarões foram mantidos em dois tanques de 80L nas mesmas condições, mas apenas um deles foi previamente tratado com probiótico comercial (Bacillus spp.) adicionado diariamente na água na concentração de 105 UFC/ml. Este protocolo foi mantido até os animais alcançarem o estágio de desenvolvimento larval necessário para os experimentos de infecção por Vibrio spp. Foram realizados três experimentos independentes de infecção: Zoea1 a Zoea3, Mísis1 a Mísis3 e Pós-larvas (PL)10 a PL14 com os seguintes tratamentos com quatro repetições cada: somente V.harveyi; probiótico comercial + V. harveyi; somente V. alginolyticus; probiótico comercial + V. alginolyticus; sem Vibrio spp. e probiótico (controle). No experimento com PL, somente os tratamentos com V. harveyi; probiótico comercial + V. harveyi e controle foram utilizados. As espécies de Vibrio foram inoculadas apenas no início de cada experimento na concentração de 107 UFC/ml. Ao final dos experimentos, uma amostra de água e camarão de cada parcela experimental foi submetida à quantificação de Vibrio spp. Adicionalmente foi realizado um teste de antagonismo in vitro de Bacillus spp. contra Vibrio spp. Nos experimentos com zoea e mísis, as larvas cultivadas no tratamento V. harveyi apresentaram uma sobrevivência significativamente inferior quando comparadas com as dos tratamentos V. alginolyticus e controle. Houve um aumento significativo na sobrevivência de larvas zoea e mísis tratadas com probiótico + V. harveyi com 81,07 e 90,13%, em comparação com as larvas infectadas apenas com V. harveyi com 12,80 e 69,13%, respectivamente. Não foram observadas diferenças significativas na sobrevivência das pós-larvas entre tratamentos. A quantidade total de Vibrio spp. na água e camarões diminuiu nos tratamentos com o uso de probiótico. O probiótico (Bacillus spp.) apresentou atividade inibitória contra Vibrio spp. in vitro. Os resultados indicaram um aumento na sobrevivência dos estágios larvais iniciais (zoea e mísis) infectadas por V. harveyi após tratamento com Bacillus spp. A administração de bactérias probióticas é uma alternativa promissora para a prevenção de Vibrio spp. na larvicultura de L. vannamei.

Práticas nutricionais saudáveis e a globalização cultural popularizaram o consumo de pratos à base de peixe cru, anteriormente restritos aos países orientais. Estimativas mostram que doenças de origem alimentar causam aproximadamente 76 milhões de casos, 325 mil hospitalizações e 5 mil mortes a cada ano, somente nos Estados Unidos. Casos com etiologia desconhecida somam 62 milhões, com 265 mil hospitalizações e 3.200 mortes. O objetivo deste estudo foi investigar a presença de Escherichia coli, Salmonella spp. e Staphylococcus aureus e cepas potencialmente patogênicas de Aeromonas spp. e Vibrio spp. em peixes comercializados em feiras livres da cidade de São Paulo, Brasil. Vinte amostras de peixes, de diferentes espécies, foram adquiridas em feiras livres e analisadas utilizando metodologia convencional para investigação de patógenos em alimentos. Altos níveis de contaminação fecal foram detectados em 25% das amostras. Staphylococcus aureus foi isolado em 10% das amostras, entretanto em valores abaixo do permitido pela legislação brasileira. Todas as amostras estavam negativas para Salmonella spp. V. parahaemolyticus não foi isolado, 30% das amostras foram positivas para outras espécies de Vibrio, inclusive Vibrio cholerae não-O1/não-O139. Aeromonas spp. , incluindo A. hydrophila foi isolada em 50% das amostras de peixe. O isolamento de Vibrio cholerae não-O1/não-O139 e Aeromonas hydrophila, assim como Staphylococcus aureus e Escherichia coli, sugere que peixes comercializados em feiras livres da cidade de São Paulo podem representar um risco para os consumidores e ser um importante veículo de transmissão de espécies enteropatogênicas. / Healthier nutritional lifestyles and cultural globalization have popularized the consumption of raw fish dishes that were previously restricted to oriental countries. Estimates indicate that food-borne diseases cause approximately 76 million illnesses, 325,000 hospitalizations and 5,000 deaths each year in the United States alone. Cases with unknown etiology account for 62 million illnesses, 265,000 hospitalizations and 3,200 deaths. The purpose of this study was to investigate the presence of Escherichia coli, Salmonella spp., Staphylococcus aureus and potentially pathogenic strains of Aeromonas spp. and Vibrio spp. in fish commercialized at the retail level in the markets of São Paulo City, Brazil. Twenty fish of different species were analysed for foodborne pathogens using conventional methodologies. High levels of faecal contamination were detected in 25% of fish samples. Staphylococcus aureus was isolated from 10% of samples; however, in each case this was below the limits established by Brazilian legislation. All samples were negative for Salmonella and 30% tested positive for others Vibrio spp., including Vibrio cholerae non-O1/non-O139. Vibrio parahaemolyticus was not found in this study. Aeromonas spp., including A. hydrophila, were isolated in 50% of fish samples. The isolation of Vibrio cholerae non-O1/non-O139 and Aeromonas hydrophila as well as Staphylococcus aureus and Escherichia coli suggests that fish commercialized in São Paulo City may represent a health risk to consumers and be an important vehicle for transmission of these enteropathogenic species.

A cidade de Jundiaí está localizada a aproximadamente 60 Km de São Paulo e tem uma população de 342.983 mil habitantes sendo que 94,37% residem na zona urbana. A cidade está inserida na bacia hidrográfica do Rio Jundiaí, rio que é formado a partir da confluência do Rio Jundiaizinho com o Ribeirão das Taipas e possui uma extensão de 123 quilômetros e sua foz está situada em Salto, na confluência do Rio Jundiaí com o Rio Tietê. Está é menor bacia hidrográfica do estado de São Paulo e também uma das mais industrializadas. A cidade de Jundiaí conta com a Estação de Tratamento de Esgotos Novo Horizonte (ETE Jundiaí), que coleta 98% dos esgotos da cidade, trata 100% de todo esgoto coletado, com eficiência de remoção de 92% de carga orgânica, esgoto que depois do tratamento é lançado no Rio Jundiaí. O objetivo deste trabalho foi utilizar ensaios de toxicidade com organismos aquáticos para avaliar a carga tóxica que chega à ETE, bem como a eficiência do tratamento biológico e a influência da estação no seu entorno. Foram coletadas amostras em 6 pontos distintos; à montante da ETE (P1), na entrada da ETE (P2), na calha de distribuição das lagoas de aeração (P3), nas 2 saídas da ETE (P4 e P5) e à jusante da ETE (P6). As amostras de afluente da ETE foram mais tóxicas que os efluentes da ETE; já os resultados das amostras do rio não apresentaram diferença. Para Vibrio fischeri os valores de CE(i)50 variaram entre 2,23% e 9,39% para a calha de entrada das lagoas de aeração, enquanto que para Daphnia similis variaram entre 15,52% e 89,95%; para a entrada da ETE os valores variaram entre 4,63% e 8,31% para Vibrio fischeri , e 17,68% e não tóxico para Daphnia similis. Nas campanhas onde foram amostradas as saídas da ETE e águas do rio, os ensaios realizados com Vibrio fischeri apresentaram resultados entre 53,55% e não tóxico para águas do rio e 29,46% e não tóxico para o efluente da ETE, já para Daphnia similis, os resultados estão entre 55,92% e não tóxico para águas do rio e 70,97% e não tóxico para o efluente da ETE. Nos ensaios realizados com Ceriodaphnia dubia, a média de nascimentos para águas do rio esteve entre 4,60 e 15,00 enquanto que para o efluente da ETE esteve entre 4,50 e 10,35 para amostra bruta. Os resultados de toxicidade comprovam a eficiência da ETE na remoção de toxicidade porém outros parâmetros devem ser observados para se comprovar o impacto de seus efluentes sobre as águas do rio. / Jundiaí is located approximately 60 kilometers from São Paulo and has a population of 342,983 habitants which 94.37% lives in urban areas. Jundiaí is included in the Jundiaí River basin witch is formed from the confluence of River Jundiaizinho with Ribeirão das Taipas, it has a length of 123 kilometers and its mouth is located in Salto, at the confluence of Jundiaí River with Tietê River. This is the smaller basin of the state and also one of the most industrialized. Jundiaí has the Novo Horizonte Wastewater Treatment Plant (NHWWP) which collects 98% of the city sewage, and treats 100% of it, with the removal of organic load efficiency 92%, which waste is drainage in Jundiaí River. The present work used toxicity tests with aquatic organisms to assess the toxic effect that comes form the station, the efficiency of biological treatment, and the influence of the station on its surroundings. Samples were collected at 6 different points, the upstream of NHWWP (P1), the entry of NHWWP (P2), in the pipeline for distribution to the aeration lagoons (P3), in the 2 outputs (P4 and P5) and downstream of NHWWP (P6). The samples of the influents were more toxic than the effluent of NHWWP and the results from the river samples did not show difference. The effective toxic concentrations EC 50 ranged between 2.23% and 9.39% for Vibrio fischeri on the pipeline entry to and lagoons, and varied between 15.52% and 89.95% for Daphnia similis, for the NHWWP enter the values ranged between 4.63% and 8.31% for Vibrio fischeri, and 17.68% and not toxic to Daphnia similis. In campaigns where sampled the outputs of NHWWP and river waters, the tests with Vibrio fischeri performed between 53.55% and not toxic to the river water and 29.46% and not toxic to the effluent of NHWWP, for while to Daphnia similis, the results were between 55.92% and not toxic to the river water and 70.97% and not toxic to the effluent of ETE. In tests conducted with Ceriodaphnia dubia, the average of births for the river water was between 4.60 and 15.00 while for the effluent of NHWWP was between 4.50 and 10.35 for crude sample. The results show the efficiency of NHWWP in the removal of toxicity but other parameters should be observed to demonstrate the impact of their effluents on the River waters.

Chez les Vibrio spp., le QS est impliqué dans de nombreuses fonctions comme la colonisation de niche écologiques, les stratégies de survie ou encore la virulence. Cependant, pour la majorité des espèces de Vibrio, la diversité des AHLs produites reste largement sous-estimée et l'étude du QS est encore limitée à quelques espèces modèles ou pathogènes. Toutefois, dans les environnements aquatiques, ces espèces sont minoritaires et les espèces les plus abondantes ne sont que très peu étudiées. Nos résultats ont révélé une importante diversité d'AHLs mais aussi, de façon surprenante, une hétérogénéité dans les phénotypes de production d'AHL au sein d'une même espèce de Vibrio. Pour la première fois, nous avons mis en évidence qu'une même souche de Vibrio pouvait présenter des phénotypes de production d'AHLs différent au cours du temps et une approche statistique a révélé l'implication de certains déterminants biotiques et abiotiques dans ces variations temporelles. Par ailleurs, une approche à micro-échelle a révélé une structuration des populations de Vibrio en unités fonctionnelles constituées de souches phylogénétiquement proches qui partagent des niches écologiques spécifiques et des comportements sociaux. Nos résultats ont mis en évidence que les modalités de communication pouvaient être hétérogènes suggérant l'absence d'un langage commun au sein de ces unités fonctionnelles. En conclusion, ce travail de thèse a permis d'apporter de nouvelles connaissances sur le QS chez les Vibrio dans l'environnement marin, de la souche à la population, et propose une vision intégrée des mécanismes de régulation de la production d'AHLs dans l'environnement. / Quorum sensing is an important mechanism among Vibrio species and is involved in many vital functions such as niche colonization, survival strategies or virulence. However, AHL diversity still largely underestimated for the majority of Vibrio species and the current knowledge on AHL-mediated QS is limited to a few pathogenic or bioluminescent species. Nonetheless, these species are weakly abundant in seawater while dominant species in the environment are poorly studied. Our results revealed a unexpected diversity of AHL molecules but also a quite surprising intra-species diversity of AHL production phenotypes. For the first time, we showed that different isolates of a single genotype switched between different AHL production phenotypes among time and we revealed the potential involvement of abiotic and biotic parameters in these variations. However, it appears that when studied at a microscale, Vibrio populations are showing a functional structuration in ecological units consisting of phylogenetically close strains sharing habitat and social traits. In this context, it was necessary to determine if these different AHL production phenotypes were associated to different micro-habitats in the water column. We did not demonstrate that a common language was spoken within ecological populations. This thesis work provide new insights on AHL-mediated QS among a broader range of species and among Vibrio populations and depicts the potential impact of multiple aspects of marine environments on AHL production.

published_or_final_version / Microbiology / Doctoral / Doctor of Philosophy

Diss. (sammanfattning) Umeå : Umeå universitet, 2009. / Härtill 4 uppsatser.