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Physiology and cell size of oligotrophic and copiotrophic aquatic bacteriaWest, A. J. January 1988 (has links)
No description available.
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Degradation of Humic Substances by Aquatic BacteriaBaiu, Saleh Hamed Salem 08 1900 (has links)
A variety of aquatic bacteria were isolated and tested for their ability to degrade humic substances and their aromatic residues/monomers which serve as precursors of the trihalomethanes (THMs) found in chlorinated drinking waters. The majority of them were Gram-negative, oxidative types dominated by pseudomonads. Most of the 146 isolates were found to utilize as their sole source of carbon several or more of ten aromatic compounds known to be products of degradation of humus and also to be precursors of THMs. The aromatics tested, with percent of the isolates utilizing the compound in parentheses, were: p-hydroxybenzoate (49), vanillic acid (48), 3,5-dihydroxybenzoic acid (16), syringic acid (19), vanillin (30), benzoic acid (27), ferulic acid (34), resorcinol (9), catechol (8) and protocatechuic acid (27).
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Rôle du chimiotactisme dans la détection des signaux et le développement de la pellicule chez Shewanella oneidensis / Role of chemotaxis in signal detection and pellicle development of Shewanella oneidensisArmitano, Joshua 10 April 2014 (has links)
Shewanella oneidensis est une bactérie aquatique capable de chimiotactisme, c'est-à-dire d'orienter sa nage en réponse aux signaux qu'elle perçoit. Mon travail de thèse s'est focalisé sur l'étude du système chimiotactique de cette bactérie. Mon premier objectif a été d'identifier de nouveaux substrats induisant une réponse chimiotactique ainsi que les chimiorécepteurs les détectant. Une approche à haut débit utilisant une banque de substrats, couplée à une recherche de substrats plus spécifiques, a permis d'identifier de nouveaux signaux. Nous avons confirmé que S. oneidensis est attirée par les accepteurs alternatifs d'électrons ainsi que par certains métaux. Nous avons montré qu'elle est attirée par le malate et le chromate et repoussée par le nickel et le cobalt. Nous avons identifié deux MCPs potentiellement impliqués dans la détection du malate et un dans la détection du chromate.Mon second objectif a été de comprendre le rôle du système chimiotactique dans la formation d'un biofilm flottant : la pellicule. Nous avons montré que le développement de la pellicule est un processus en trois étapes déclenché par la détection de l'oxygène en condition statique, probablement par aérotactisme. Nous avons mis en évidence l'implication inattendue du chimiotactisme dans la formation de la pellicule. En effet des mutants délétés de gènes codant pour des éléments du système chimiotactique ne forment pas de pellicule normale. Le développement de la pellicule met en jeu d'autres signaux chimiotactiques, générés au sein de la pellicule, qui pourraient intervenir dans la localisation des cellules et l'homogénéisation de la pellicule au cours de sa maturation. / Shewanella oneidensis is an aquatic bacterium capable of chemotaxis, meaning that it can change its direction in response to detected signals. My thesis focused on the study of the chemotaxis system of this bacterium.The first objective of my thesis was to identify new substrates inducing a chemotactic response and the chemoreceptors involved in their detection. A high-throughput technique involving a library of solutes coupled with a search of more specific compounds allowed to identify new signals. We confirmed that S. oneidensis is attracted toward alternative electron acceptors and by several metals. We showed that S. oneidensis is attracted toward malate and also chromate. Finally, we identified two repellents, nickel and cobalt. After construction of deletion mutants, we identified two MCPs potentially involved in malate detection and one in chromate detection.The second objective of my thesis was to understand the role of the chemotaxis system in the formation of a floating biofilm: the pellicle. We first characterized the pellicle development through time, revealing that it is a three-step process. We then highlighted the unexpected role of the chemotaxis system in pellicle formation. Indeed mutants deleted of genes coding for chemotaxis elements are not able to form a pellicle or form an abnormal one. We showed that oxygen is the main signal triggering pellicle formation in static condition and that it is probably detected through aerotaxis. Pellicle development also involves other chemotactic signals produced in the pellicle which could be used in the localization of cells at the air-liquid interface but also in the homogenization of the pellicle.
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Bottom Sediment Analysis of the Recreational Waters of Upper Sabino CreekMcKee, Patrick L., Brickler, Stanley K. 16 April 1977 (has links)
From the Proceedings of the 1977 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 15-16, 1977, Las Vegas, Nevada / Bottom sediment quality of the upper four miles of Sabino Creek in the Santa Catalina mountains near Tucson, Arizona was examined from September, 1975 through August, 1976. Two primary bottom sediment parameters were examined: 1) sediment fecal bacterial concentrations, and 2) sediment particle size distribution. Analyses of bottom sediment parameters and selected surface water parameters were conducted to ascertain interrelationships between bottom sediment quality and surface water quality. Results indicate the importance of bottom sediments in the overall quality of the Creek. Bottom sediment fecal bacterial concentrations have a significant influence on surface water fecal bacterial concentrations through suspension of sediment stored bacteria into the overlying water. Significantly higher bacterial concentrations were observed during highest recreational use periods.
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Avaliação do processo de morte celular em bactérias aquáticas em dois modelos de ecossistemas aquáticos tropicaisSilva, Thiago Pereira da 29 March 2012 (has links)
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Previous issue date: 2012-03-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O bacterioplâncton é um dos componentes da cadeia trófica em ecossistemas
aquáticos, sendo regulado por fatores como disponibilidade de nutrientes,
temperatura, predação e infecção viral. A morte de bactérias é caracterizada como o
processo de perda funcional e morfológica da célula e tem função de controlar a
abundância e produção bacteriana, com significado importante na ciclagem de
carbono e nutrientes nos ecossistemas aquáticos. No entanto, o processo de morte
celular em bactérias aquáticas é desconhecido. Ainda não se sabe se a morte celular
programada (MPC), processo regulado e bem conhecido em organismos eucariotos,
ocorre em bactérias aquáticas. Este trabalho teve por objetivo investigar a ocorrência
de MCP em bactérias aquáticas utilizando dois modelos de ecossistemas: lago Batata
e lago dos Manacás. O lago Batata é um ecossistema amazônico de inundação e
encontra-se divido em duas áreas: impactada e natural. O lago dos Manacás é um
ecossistema artificial localizado em Minas Gerais. Três grupos de bactérias,
provenientes do lago dos Manacás, lago Batata – área natural e lago Batata – área
impactada foram estudados. As amostras de água foram coletadas na sub-superfície
dos lagos e processadas para análises da viabilidade celular por microscopia de
fluorescência e da fragmentação de DNA por citometria de fluxo. Em paralelo,
amostras do lago Batata – área impactada foram processadas para microscopia
eletrônica de transmissão (MET) para caracterizar a diversidade ultraestrutural da
comunidade bacteriana e investigar a ocorrência de alterações celulares bacterianas.
Os resultados da viabilidade celular utilizando marcadores específicos para
integridade de membrana (LIVE/DEAD BacLight) mostraram diretamente a presença
de bactérias vivas/viáveis e mortas/inviáveis . O lago Batata apresentou maior
proporção de morte celular bacteriana (36,20%) em comparação com o lago dos
Manacás (19,66%). As análises de fragmentação de DNA (ensaio TUNEL) mostraram
que a MCP constitui um fenômeno presente nos ecossistemas aquáticos estudados,
com maior ocorrência na área impactada do lago Batata. A MET revelou a presença
de bactérias aquáticas com grande diversidade ultraestrutural, representada por
diferenças morfológicas quanto ao envoltório celular, cápsula, mesossomos, vesículas
membranosas, partículas aderidas e tilacóides. Além disso, 34,28% das bactérias
apresentavam vírus no citoplasma. A diversidade ultraestrutural pode representar a
ampla diversidade metabólica e adaptativa bacteriana, enquanto a presença de vírus
parece relacionada com a morte bacteriana. As análises de integridade ultraestrutural
mostraram que (i) a maior proporção de bactérias encontrava-se com alterações
ultraestruturais indicativas de processo de morte, (ii) a frequência de ocorrência de
cápsula foi menor nas bactérias vazias, (iii) bactérias com alterações apresentaram
maior frequência de partículas aderidas, e (v) o número médio de fagos por secção foi
significativamente maior nas bactérias alteradas em comparação com as bactérias
intactas. A MET mostrou a ocorrência de alterações ultraestruturais típicas de MCP,
como retração e condensação citoplasmáticas. Em conjunto, nossos dados ressaltam
morte bacteriana como um evento importante atuando na regulação da comunidade
bacteriana e demonstra, pela primeira vez, a ocorrência de MCP em bactérias
aquáticas. A MCP pode ter significado funcional como um dos mecanismos
desenvolvidos para sobrevivência da comunidade bacteriana. / The bacterioplankton is an important component of the food web structure in aquatic
ecosystems and it is regulated by many factors such as nutrient supply, temperature,
predation and virus infection. Bacterial death is characterized by functional and
morphological loss of the bacterial cell with roles in the control process of abundance
and bacterial production of aquatic ecosystems and functional meaning in the carbon
and nutrient cycles. However, the cell death process in aquatic bacteria remains to be
defined. Programmed cell death (PCD) is a regulated process largely known in
eukaryotic organisms. There are not studies dealing with PCD occurrence in aquatic
bacteria. This study aimed to investigate the occurrence of PCD in free-living aquatic
bacteria in two models of aquatic ecosystems: Batata lake and Manacás lake. Batata
Lake is located on floodplain Trombetas river in northern of Brazilian Amazon. This
ecosystem has been impacted for bauxite tailings over teen years and it is presently
divided in impacted and natural stations. Manacás Lake is an artificial system located
in Minas Gerais. Three groups of bacteria from Manacás Lake, Batata lake – impacted
area - and Batata lake – natural area -were studied. Water samples were collected
from the subsurface of these lakes and processed for analyses of bacterial viability by
fluorescence microscopy and DNA fragmentation by flow citometry. In parallel,
samples from Batata lake – impacted area - were processed for transmission electron
microscopy (TEM) for characterization of the bacterial community ultrastructural
diversity and investigation of bacteria alterations. Our cell viability results using
specific markers for membrane integrity (LIVE/DEAD BacLight) showed directly the
presence of live/viable and dead/ not viable bacteria. Batata lake presented a higher
proportion of bacterial death (36,20%) compared to Manacás lake (19,66%). DNA
fragmentation analyses (TUNEL assay) showed that PCD is a phenomenon occurring
in all aquatic ecosystems investigated, with higher frequency in the Batata lakeimpacted
area compared to the other ecosystems. Our TEM analyses revealed a great
bacterial ultrastructural diversity represented by morphological differences in the
cellular envelope, capsule, mesosomes, membrane vesicles, attached particles and
thylacoids. Moreover, around 34,28% of the bacteria showed virus in their cytoplasm.
The ultrastructural diversity may represent the large metabolic and adaptative diversity
of aquatic bacteria while the presence of virus may be related to bacterial death. Our
ultrastructural integrity analyses showed that (i) the higher proportion of bacteria was
in death process or dead (damaged and empty), (ii) the capsule frequency is lower in
empty bacteria, (iii) the higher bacteria-particle association was found in altered
bacteria, (iv) the mean number of viruses per cell section was higher in altered
compared to intact bacteria. TEM also showed the presence occurrence of typical
ultrastructural changes indicative of MPC, such as cell retraction and condensation.
Altogether, our data demonstrate that PCD occur in aquatic bacteria, and that this
event may be a survival mechanism for bacterial communities in these ecosystems.
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A Bacterial Water Quality Investigation of Canyon LakeHorak, W. F., Lehman, G. S. 20 April 1974 (has links)
From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / Fecal coliform counts in relation to number of swimmers along with fecal streptococci counts of water samples from Canyon Lake in central Arizona are reported. The presence of swimmers was related to an increase in fecal coliforms which was attributed to organisms shed from the swimmers and from agitation of the bottom sediments, consequently dispersing much of the bacteria contained in the benthos. From sampling of the swimming areas it was determined that livestock waste was the primary source of pollution (a greater number of fecal streptococci was found than fecal coliforms), but this interpretation could be misleading due to the higher survival rate of fecal strep than that of fecal coliform organisms.
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