Made available in DSpace on 2014-06-11T19:29:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-16Bitstream added on 2014-06-13T20:38:53Z : No. of bitstreams: 1 tebaldi_r_me_arafcf.pdf: 300893 bytes, checksum: dc69e3a75aeeb349d9af75e741a2e2ca (MD5) / Universidade Estadual Paulista (UNESP) / A constante preocupação com a qualidade da água destinada ao consumo, a presença de sabores e odores desagradáveis decorrentes da adição de flúor e cloro nas águas de abastecimento público e a falta de suprimentos adequados de água potável, tem provocado uma contínua demanda por água mineral. A relativa escassez de estudos envolvendo a qualidade microbiológica da água mineral, principalmente na água mineral gaseificada artificialmente, gerou esta pesquisa que tem por objetivo, avaliar e comparar a qualidade bacteriológica de águas minerais sem gás e gaseificadas artificialmente, em embalagens descartáveis, de oito marcas comercializadas em supermercados das cidades de Ribeirão Preto e Araraquara - SP. As duzentos e quarenta amostras analisadas foram divididas em três lotes com cinco unidades gaseificadas e cinco sem gás de cada marca. Foram realizadas análises para determinação de bactérias do grupo coliforme, bactérias heterotróficas e Pseudomonas aeruginosa. Para análise de coliformes totais e E. coli utilizou-se a técnica de substratos cromogênicos, para Pseudomonas aeruginosa utilizou-se a técnica de tubos múltiplos específica e para contagem de bactérias heterotróficas foi utilizada a técnica de cultivo em profundidade. Para as cento e vinte amostras não gaseificadas analisadas (100%), verificou-se a presença de coliformes totais em oito amostras (6,67%), presença de E. coli em seis amostras (5%), presença de Pseudomonas aeruginosa em cinco amostras (4,2%), e 102 amostras (85%) apresentaram contagem de bactérias heterotróficas maior que 500 UFC/mL. Para as cento e vinte amostras gaseificadas analisadas verificou-se que nenhuma delas apresentou contaminações para o grupo coliforme (totais e E. coli) e para Pseudomonas aeruginosa. Apenas três amostras (2,5%) apresentaram contagens superiores a 500 UFC/mL para bactérias heterotróficas... / The constant concern with the water quality reserved to human consumption, the presence of tastes and odors caused by the addition of fluoride and chlorine in public water supplies and the destitution of adequate supplies of potable water has challenged a continuous demand for mineral water. The relative privation of studies on the bacteriological quality of mineral water, mainly in artificially carbonated mineral water generated this project that purpose to value and to compare the microbiological quality of mineral water without gas and carbonated artificially, in dismissible tacking, of eight types, sold in supermarkets in the cities of Araraquara/SP and Ribeirão Preto/SP. The two hundred forty analyzed samples were divided in shares with five unities carbonated mineral water and five without gas. There were put into practice analysis for determination of coliform bacteria, heterotrophic bacteria and Pseudomonas aeruginosa. To analysis of total coliform and E. coli it was used the chromogenic substrates technique, for Pseudomonas aeruginosa used the multiple tube specific technique and to counting heterotrophic bacteria, it was used the technique of growing in depth. To the one hundred twenty samples no carbonated water analyzed (100%), was checked the presence of total coliforms in eight samples (6,67%), presence of E. coli in six samples (5%), presence of Pseudomonas aeruginosa in five samples (4,2%), and one hundred two samples (85%) was with counts above 500 CFU/mL for heterotrophic bacteria. To the one hundred twenty carbonated water samples analyzed (100%), was checked that no samples analyzed was contaminated to the coliform group (total and E. coli) and to Pseudomonas aeruginosa. Just three samples (2,5%) present counts above 500 CFU/mL for heterotrophic bacteria. All the brands of the samples no carbonated water tested (100%) presents out of the specifications of Brazilian legislation in one or more parameters analyzed

Thesis (DTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017. / Industrial wastewater management pertaining to the mining industry has become increasingly stringent, with companies being required to develop environmentally benign wastewater management practices worldwide. The industries that utilise cyanide compounds for the recovery of precious and base metals in a process known as the cyanidation process, have contributed substantially to environmental deterioration and potable water reserve contamination due to the discharge of poorly treated, or untreated, cyanide containing wastewater. Hence, a biotechnological approach was undertaken in this study to remediate free cyanide (CN-) and thiocyanate (SCN-), which are the major chemical contaminants which are normally found in cyanidation wastewaters. Furthermore, this biotechnological approach was investigated to understand the fundamental aspects of using this approach such that the information gathered can be utilized in pilot plant studies. Therefore, bioprospecting of potential CN- and SCN--degrading organisms was undertaken using two approaches; (i) culture-dependent approach and (ii) culture-independent approach. Using the culture-dependent approach, Pseudomonas aeruginosa STK 03, Exiguobacterium acetylicum and Bacillus marisflavi were isolated from an oil spill site and river sediment samples, respectively. STK 03 was evaluated for the biodegradation of CN- and SCN- under alkaline conditions. The organism had a CN- degradation efficiency of 80% and 32% from an initial concentration of 250 and 450 mg CN-/L, respectively. Additionally, the organism was able to degrade SCN-, achieving a degradation efficiency of 78% and 98% from non- and CN- spiked cultures, respectively. Furthermore, the organism was capable of heterotrophic nitrification but was unable to denitrify aerobically, with the autotrophic degradation of CN- by STK 03 being abortive.

Dans l'océan, la respiration microbienne est considérée comme le principal processus représentatif de l’oxydation biologique de la matière organique. La production correspondante de CO2 métabolique a été estimée à environ 22 Pg C a-1. Cependant, les intensités respiratoires qui se déroulent in situ sont généralement trop faibles (de plusieurs ordres de grandeur) pour être accessibles aux méthodes de mesure directes actuellement disponibles. Certaines sondes fluorescentes, comme le DiOC6(3) (Molecular Probes, USA) se sont révélées être très sensibles à l’intensité de la différence de potentiel électrochimique du proton (?µH+), qui caractérise les membranes mitochondriales et plasmiques qui portent le système respiratoire chez les cellules eucaryotes et procaryotes. Chez les mitochondries, le ?µH+ présente une relation linéaire avec le flux d'oxygène. À notre connaissance, aucune relation de ce type n'avait été établie dans le cas de cellules entières marines (micro-organismes). Lors de travaux antérieurs, G. Grégori s’est intéressé à la vitesse de respiration à l’obscurité d’une culture monospécifique de la Chlorophyceae Dunaliella tertiolecta (Butcher) en utilisant un oxygraphe à haute résolution (Oroboros) et une coloration des cellules par le DiOC6(3). Une relation linéaire a été mise en évidence et standardisée, entre la vitesse d’absorption d'oxygène par D. tertiolecta et son intensité de fluorescence verte spécifique induite par le DiOC6(3), permettant ainsi la mesure par cytométrie de flux de la vitesse de respiration de D. tertiolecta. L'étape suivante consiste à étendre la méthode aux procaryotes hétérotrophes, principaux responsables de la minéralisation de la matière organique dans l'océan. Dans le présent travail sont présentés les résultats obtenus sur l’eubactérie Pseudomonas nautica 617, une souche qui a été isolée dans notre laboratoire par P. Bonin en 1987. / In the Ocean, microbial respiration is considered as the major process representative of the organic matter biological oxidation. The corresponding metabolic CO2 production was estimated to be about 22 Pg C y–1. However, the in situ respiration rate is generally too low (by several orders of magnitude) to be accessible to the available direct measurement methods. Some fluorescent probes, such as DiOC6(3) (Molecular Probes, USA) have been shown to be very sensitive to changes in the proton electrochemical potential difference (?µH+), characterising mitochondrial and plasmic membranes bearing the cell respiratory system in eukaryotic and prokaryotic cells. In mitochondria, ?µH+ is linked to the flux of oxygen uptake by a linear relationship. To our knowledge, no such relationship has been established in the case of whole marine cells. In a previous works, G. Grégori addressed the dark respiration rate of the Chlorophyceae Dunaliella tertiolecta (Butcher) in axenic culture, both directly by using a highly sensitive oxygraph (Oroboros) and by staining cells with DiOC6(3). A linear relationship was established and standardized between the oxygen uptake by D. tertiolecta and its green fluorescence induced by DiOC6(3), enabling the measure by flow cytometry of the respiration rate of D. tertiolecta. The next step is to extend the method to heterotrophic prokaryotes which are responsible for most of the mineralization of the organic matter in the ocean. In the present work are presented results obtained on the eubacteria Pseudomonas nautica 617, a strain that has been isolated in our laboratory by P. Bonin in 1987.

Les bactéries et microalgues marines sont acteurs clés du fonctionnement des écosystèmes océaniques et leur contribution dans les cycles biogéochimiques majeurs est largement reconnue. Dans ce contexte, il apparaît essentiel de mieux comprendre les interactions existant entre bactéries et microalgues. Dans l’environnement marin, les interactions spécifiques entre microorganismes nécessitent une forte proximité qui n’est souvent rendue possible que par un attachement cellulaire. La première partie de ce travail de thèse a consisté à sélectionner les microalgues qui présentaient des bactéries physiquement attachées. Deux diatomées appartenant aux genres Thalassiosira et Chaeoceros ont été retenues afin d’étudier leur microflore épibionte issue d’associations à long terme (culture de microalgues établies depuis plusieurs années) et à court terme (microalgues prélevées directement dans l’environnement). Ces travaux ont permis de mettre en évidence une forte ressemblance des communautés épibiontes dans les associations à long terme, qui s’opposait à la forte différence des épibiontes issus des associations à court terme. Les communautés d’épibiontes bactériens étaient majoritairement composées d’alpha- et gammaprotéobactéries, mais aussi de Bacteroidetes et d’actinobactéries. Cette étude a également permis de mettre en évidence que la surface des microalgues représentait un écosystème particulier puisque près de la moitié des épibiontes isolés correspondaient à de nouveaux taxons (genres et espèces). Une de ces souches qui constitue un nouveau genre a été complètement caractérisée, contribuant à l’enrichissement de la diversité bactérienne décrite. Enfin, la nature des interactions entre les deux diatomées et leurs bactéries épibiontes a été analysée par l’intermédiaire de co-cultures, afin d’identifier une interaction forte, qui pourra être examinée par transcriptomique. De très nombreuses interactions commensalismes ont été mises en évidence, reflet de la reminéralisation de la matière organique par les bactéries. Cependant, un faible impact des bactéries sur la croissance des microalgues a été observé. Les conditions expérimentales qui excluent au maximum les stress abiotiques et biotiques, masquent peut-être les interactions qui pourraient se produire dans un environnement naturel plus fluctuant. Ces résultats témoignent de la complexité des interactions biotiques, fournissent des méthodes et des organismes modèles permettant de les étudier et soulèvent de nombreuses hypothèses exaltantes pour les travaux futurs. / Marine microalgal and bacterial contribution to the global biogeochemical cycles is largely recognized and lead to define them as key actors of oceanic ecosystems. In this context, it is essential to better understand the interactions occurring between bacteria and microalgae. In the marine environment, specific interactions between microorganisms require tight physical association that is made possible by cellular attachment. In this work, we first selected microalgae with physically attached bacteria. Two diatoms belonging to the genus Thalassiosira and Chaetoceros were selected to study the epibiotic microflora from long-term (microalgae in culture) and short-term (microalgae directly collected from natural communities) associations. This work highlighted strong similarities between epibiotic assemblages from long-term associations and a higher difference for epibiotic communities from short-term associations. The bacterial epibiotic assemblages were mainly composed of Alpha- and Gammaproteobacteria but also Bacteroidetes and Actinobacteria. This study also highlighted that the surface of microalgae represented a peculiar ecosystem where nearly half isolates constituted new taxa (genera and species). One of them representing a new genus has been completely characterized, contributing to the enrichment of the described bacterial diversity. Finally, the nature of interactions between diatoms and their epibiotic bacteria was analyzed by co-culturing to identify strong interactions, to be further examined by transcriptomics. Numerous commensal interactions have been identified, corresponding to the bacterial remineralization of organic matter. However, only small effects of bacteria on microalgal growth were observed. The experimental conditions that exclude a maximum of abiotic and biotic stresses may mask potential interactions that could occur in an unstable natural environment. These results reflect the complexity of biotic interactions, provide methods and model organisms to study them, and raise many exciting hypotheses for future work.

Heterotrophic bacterioplankton dynamics have seldom been assessed in the Red Sea, an exceptionally warm oligotrophic basin, which could be used as a model for the future ocean. To understand the function of heterotrophic bacteria in biogeochemical cycles and the flows of matter and energy to higher trophic levels, it is peremptory to understand how bacterial growth is controlled. Bottom-up (resources availability), top-down (mortality by predators and viruses) and temperature are the main hypotheses of control of bacterial activity and stocks. This dissertation aims to assess the spatial-temporal variability of heterotrophic bacteria and their interactions with diverse sources of dissolved organic matter (DOM) through the observed effects on bacterial growth rates and productivity in coastal environments of the central Red Sea. To that end we conducted a total of 66 shortterm incubations (4-6 days) concurrently with the whole microbial community and predator-free (by filtration) in various shallow ecosystems characterized by different dominant sources of DOM. Frequent sampling combined flow cytometry and biogeochemical analysis allowed us to measure bacterial standing stocks, including the carrying capacity (maximum abundances), growth rates, characterize DOM concentrations and lability, assess bacterial DOM consumption rates and biomass production and ultimately quantify bacterial growth efficiencies. Our findings suggest that although bacteria seemed to thrive in nutrient-sufficient waters, the central coastal Red Sea is characterized by unusually low bacterial standing stocks (4.05 ± 0.31 x105 cells ml-1), probably controlled by protistan grazing. At the same time, bacterioplankton showed high potential to grow (0.35-1.75 d-1, reaching 4.16 d-1 when dilution and pre-filtration were performed). Even though the highest specific growth rates were observed during the warmer periods, we did not find any consistent relationship with temperature. While temperature seemed not to constrain bacterial specific growth rates, we observed a tight link between bacterial growth and resource availability in terms of both quantity and quality. Overall, by surveying one of the warmest marine regions on Earth, this dissertation provides detailed insights into heterotrophic bacterioplankton dynamics and how bottomup, top-down and temperature regulate them in tropical waters, a vast geographical extension of the world oceans that had remained strongly undersampled to date.

No description available.

The objectives of this study were to determine: (1) whether or not heterotrophic microorganisms exert an effect on the trihalomethane (THM) or total organic halogen (TOX) formation potentials of algal extracellular products (ECP), and (2) whether or not diurnal cycling of THM and TOX precursors occurs in vitro. These objectives were addressed through culture studies of heterotrophic microorganisms and pure algae from both the green and blue-green divisions. Culture conditions were varied to study different aspects of algal and bacterial interactions. Results from continuous light assays indicated that heterotrophs, grown in the same culture vessel with algae, affected an increase in the potential of chlorinated culture filtrate to form THMs. No significant changes in TOX-formation potential were observed. Heterotrophs grown in volumes of algal ECP (cell-free filtrates of algal cultures) used the algal-produced organic carbon as their sole carbon source. These microorganisms further reduced both the dissolved organic carbon (DOC) concentration and the concentration of the DOC fraction that reacted to form TOXs. The fraction which produced THMs was not reduced. Heterotrophic microorganism metabolic activity increased the rate at which THMs fanned from chlorinated algal ECP but did not alter the seven-day THM-formation potentials. Their activity also increased the initial rate of TOX formation, but decreased the seven-day formation potential of these compounds. Attempts to demonstrate diurnal cycling of the concentration of THM precursors and other halogenated organic precursors, a phenomenon previously demonstrated in a eutrophic reservoir, were unsuccessful. / M.S.

In aquatic environments the availability of nitrogen (N) generally limits primary production. N2-fixing prokaryotes (diazotrophs) can convert N2 gas into ammonium and provide significant input of N into the oceans. Cyanobacteria are thought to be the main N2-fixers but diazotrophs also include a wide range of heterotrophic bacteria. However, their activity and regulation in the water column is largely unknown. In this thesis the distribution, diversity, abundance, and activity of marine and estuarine heterotrophic diazotrophs was investigated. With molecular methods targeting the nifH gene, encoding the nitrogenase enzyme for N2 fixation, it was shown that diverse nifH genes affiliating with heterotrophic bacteria were ubiquitous in surface waters from ten marine locations world-wide and the estuarine Baltic Sea. Through enrichment cultures of Baltic Sea surface water in anaerobic N-free medium, heterotrophic N2 fixation was induced showing that there was a functional N2-fixing community present and isolates of heterotrophic diazotrophs were obtained. In Sargasso Sea surface waters, transcripts of nifH related to heterotrophic bacteria were detected indicating heterotrophic N2-fixing activity. Nitrogenase expression is thought to be highly regulated by the availability of inorganic N and the presence of oxygen. Low oxygen zones within the water column can be found in association with plankton. The presence of diazotrophs as symbionts of heterotrophic dinoflagellates was investigated and nifH genes related to heterotrophic diazotrophs rather than the cyanobacterial symbionts were found, suggesting that a symbiotic co-existence prevailed. Oxic-anoxic interfaces could also be potential sites for heterotrophic N2 fixation. The Baltic Sea contains large areas of anoxic bottom water. At the chemocline and in anoxic deep water heterotrophic diazotrophs were diverse, abundant and active. These findings extend the currently known regime of N2 fixation to also include ammonium-rich anaerobic waters. The results of this thesis suggest that heterotrophic diazotrophs are diverse and widely distributed in marine and estuarine waters and that they can also be active. However, limits in the knowledge on their physiology and factors which regulate their N2 fixation activity currently prevent an evaluation of their importance in the global marine N budget.

Le cycle du carbone est régi principalement par les phénomènes de production et de reminéralisation de la matière organique le long de la colonne d'eau. Les acteurs principaux de cette reminéralisation sont les procaryotes hétérotrophes, dont les actions peuvent être mesurées sur l'ensemble de la colonne d'eau via la respiration procaryotique. Au cours de ce travail de thèse, un suivi à long terme et en temps réel des conditions hydrologiques et biogéochimiques (température potentielle, salinité et oxygène dissous, O2) a été mené entre 2008 et 2010 en Méditerranée Nord Occidentale, sur le site ANTARES. Ces observations ont permis de mettre en évidence les influences d'évènements ponctuels (convection hivernale d'eau profonde) par advection sur ces paramètres hydrologiques et biogéochimiques. Ces influences, directes ou indirectes, vont également avoir des incidences sur la concentration en matière organique et donc sur le potentiel reminéralisateur du milieu profond. Le suivi temporel de la concentration d'O2 a également permis de mettre en évidence une diminution de la concentration globale de 2.6 µmol O2 dm-3 a-1, sur une période de trois ans. Le développement au sein du laboratoire et en collaboration avec le Centre de Physique des Particules de Marseille (CPPM) d'un nouvel outil en équipression, le IODA6000 (In situ Oxygen Dynamics Autosampler), mesurant directement et à haute fréquence la dynamique de l'O2 a permis d'obtenir des vitesses de respiration procaryotique à 2000 m de profondeur depuis décembre 2009 sur le site ANTARES. / The carbon cycle is mostly driven by production and remineralisation processes which are constraining organic matter concentration along the water column. The main actors of the remineralisation are the heterotrophic prokaryotes, which actions can be measured from surface to deep by the prokaryotic respiration. During this PhD thesis, a long term real time monitoring of hydrological and biogeochemical conditions (potential temperature, salinity and dissolved oxygen O2) has been carried out between 2008 and 2010 in the North Occidental Mediterranean Sea, at the ANTARES site. Influence of punctual events has been observed which seem to be related to winter deep sea convection and subsequent advection, changing hydrological and biogeochemical properties observed at the ANTARES site. These direct or indirect modifications will have consequences on the organic matter concentration and therefore on the deep-sea remineralisation potential. The temporal monitoring of O2 concentration has also allow us to estimate the deep water oxygen consumption of 2.6 µmol O2 dm-3 a-1, during a three year period. The development in our laboratory in collaboration with Centre de Physique des Particules de Marseille (CPPM) of a new equipressured tool, the IODA6000 (In situ Oxygen Dynamics Autosampler), measuring directly and at high frequency the O2 concentration, allowed us to measure PR rates at 2000 m depth since December 2009 at the ANTARES site. This unique ongoing time series shows a mean prokaryotic respiration rates higher (0.2 µmol O2 dm-3 d-1) than expected by literature (5.5 10-3 µmol O2 dm-3 d-1), with a high temporal variability (from 8 10-3 to 0.5 µmol O2 dm-3 d-1).

Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2008. / Includes bibliographical references (p. 54-59). / (cont) An increased understanding of heterotrophic bacterial strategies for acquiring nutrients and trace elements is critical for elucidating their impact on biogeochemical cycling in the ocean. It is estimated that iron is a limiting nutrient for phytoplankton growth in over 30% of the open ocean, but still little is known about bacterial strategies for iron acquisition. Siderophore (Fe ligand) production by bacteria may play a major role in influencing the bioavailability of iron in the ocean. Despite the importance of siderophores in the environment, only limited information from a select group of bacteria is available. On a cruise through the Costa Rica Dome (CRD) upwelling region in July 2005, a library of 867 isolates from five depth profiles inside and outside of the dome was obtained and screened for siderophore production using the Chrome Azurol-S (CAS) assay. Phylogenetic affiliation of 134 isolates was determined by sequencing the 16s rDNA gene, and determined that gamma proteobacteria such as Alteromonas, Pseudoalteromonas, Halomonas, and Marinobacter dominated the collection, while alpha-proteobacteria such as Roseobacter were also represented. The isolates obtained from stations in the CRD showed greater siderophore-producing capabilities between 55m and 100m while strains isolated from outside the CRD had shallower peak (-8-35m) production. Functional group determination showed that hydroxamate production dominated from 50-150m, while hydroxamate and catechol production is roughly equal in shallower waters. By characterizing the siderophores produced by these isolates and determining the genetic make-up of the population, these findings further our understanding of how heterotrophic microbes affect biogeochemical processes and the competitive nature of nutrient acquisition. / by Whitney B. Krey. / S.M.