A odontologia reabilitadora moderna preconiza cada vez mais o uso de implantes dentais para a substituição de dentes ausentes. É sabido que micro-organismos presentes na cavidade oral, em especial os relacionados à doença periodontal, são responsáveis pelos maiores índices de insucesso dos implantes. Este trabalho estudou a ocorrência de infiltração bacteriana através da interface implante-conector protético de implantes Cone Morse (CM) e Hexágono Interno (HI) após a associação com uma pasta antimicrobiana ou a adição de sais de prata nos pilares. Foram utilizados 72 implantes odontológicos de titânio (PROSS® - Sistema de Implantes, Dabi-Atlante, Ribeirão Preto, Brasil), 36 com conexão do tipo hexágono interno e 36 com conexão do tipo cone-morse, divididos em grupos, da seguinte forma: Grupo Pasta Antimicrobiana- 12 conjuntos implantes HI/conectores protéticos e 12 conjuntos implantes CM/conectores protéticos, Grupo Íons de Prata- 12 conjuntos implantes HI/conectores protéticos e 12 conjuntos implantes CM/conectores protéticos e Grupo Controle- 12 conjuntos implantes HI/conectores protéticos e 12 conjuntos implantes CM/conectores protéticos. Os implantes e os conectores protéticos foram retirados de suas embalagens para aplicação do torque final (20N/cm). Antes disso, em um dos grupos experimentais, uma camada da pasta antimicrobiana foi aplicada sobre a superfície interna dos implantes e conectores protéticos e seus respectivos parafusos. Os conjuntos implantes-conectores foram parcialmente imersos na solução de saliva humana em tubos de ensaio e incubados em estufa bacteriológica a 37°C durante 7 dias. Após esse período, amostras do conteúdo interno dos conjuntos implantes-conectores protéticos dos 3 grupos foram colhidas com o objetivo de detectar e quantificar os micro-organismos presentes, utilizando para isto, a técnica de hibridização com sondas de DNA genômico DNA Checkerboard. Os implantes de conexão do tipo cone morse apresentaram menores valores de contagem de bactérias quando comparados aos implantes hexágono interno no grupo Controle (p<0,001), já para o grupo Íons de prata e Pasta antimicrobiana, foi observado comportamento inverso, maiores valores de contagem de bactérias para os implantes Cone Morse. Comparando-se os implantes de mesma conexão, entre os 03 grupos examinados, as amostras dos implantes Cone Morse dos grupos Controle, Íons de prata e Pasta antimicrobiana apresentaram valor de contagens de micro-organismos em ordem crescente. Os implantes de conexão hexágonal interna dos grupos Controle apresentaram maiores valores de contagens de micro-organismos seguidos pelos implantes do grupo Pasta antimicrobiana e Íons de prata, respectivamente. A partir dos resultados obtidos pode-se concluir que houve a passagem dos 43 micro-organismos analisados in vitro através da interface implante/componente protético em ambos os sistemas avaliados. Para ambos os tratamentos (adição de sais de prata às paredes dos pilares protéticos e aplicação da pasta antimicrobiana no interior dos implantes) houve diminução da infiltração microbiana no interior daqueles sistemas de conexão do tipo Hexágono Interno. / The contemporary and modern dentistry has been preconized the use of dental implants for replacement of missing teeth. The micro-organisms presents in oral environment, particularly those related to periodontal disease, are responsible for the highest failure rates of dental implants. This study evaluated the occurrence of bacterial leakage through the abutmentimplant interface in Morse Taped (CM) and Hexagon Internal (HI) dental implants after the association with antimicrobial paste or addition of silver salts on the abutments. 72 titanium dental implants (Pross ® - Implant System, Dabi-Atlante, Ribeirão Preto, Brazil), 36 with internal hexagon connection type and 36 with cone-morse connection type, divided into groups as follows: group Antimicrobial Paste -12 implants HI / prosthetic connectors and 12 implants CM / prosthetic connectors, group Ion Silver-12 implants HI / prosthetic connectors and 12 implants CM / prosthetic connectors and Control Group-12 implants HI / prosthetic connectors and 12 implants CM / prosthetic connectors. The implants and prosthetic connectors have been removed from their packaging for applying of final torque (20N/cm). Previously, in one experimental group, a layer of antimicrobial paste was applied on the inner surface of implants and prosthetic connectors. The sets connector/implants were partially immersed in human saliva solution in test tubes and incubated in bacteriological oven at 37°C for 7 days. Subsequently, samples of the contents of internal prosthetic sets implantconnectors of the 3 groups were collected to detect and quantify micro-organisms, through the DNA Checkerboard Hybridization Technique. The morse taper implants had significantly lower bacterial count compared to internal hexagon implants in the control group (p <0.001), while for the group of Silver Ion and antimicrobial Paste, we observed an inverse behavior, higher counts of micro-organisms for Morse taper implants. Comparing the same connection implants, among the 03 groups examined, samples of implants Morse Taper Control groups, Antimicrobial Paste and Silver ions exhibited values of counts of micro-organisms in ascending order. The internal hexagon implants of the Control group showed higher counts of microorganisms followed by Antimicrobial Paste and Silver Ions groups, respectively. The 43 species analyzed in vitro infiltrated through the interface implant / abutment in both systems evaluated; For both the treatments (adding silver salts in the abutments walls and applying of the antimicrobial paste within the implants) there was decreased microbial leakage through the interface connection for the internal hexagon dental implants

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-01-14T09:12:10Z No. of bitstreams: 2 Dissertação - Midiana Gusmão dos Santos - 2015.pdf: 7686250 bytes, checksum: 6f9cdf0c78f828c4dad082acfc67f6c8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-01-15T08:39:26Z (GMT) No. of bitstreams: 2 Dissertação - Midiana Gusmão dos Santos - 2015.pdf: 7686250 bytes, checksum: 6f9cdf0c78f828c4dad082acfc67f6c8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-01-15T08:39:26Z (GMT). No. of bitstreams: 2 Dissertação - Midiana Gusmão dos Santos - 2015.pdf: 7686250 bytes, checksum: 6f9cdf0c78f828c4dad082acfc67f6c8 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-04-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The fresh almond is the main form of consumption of the Brazil nut, however, co-products such as water-soluble extract can be exploited commercially. Aqueous extracts are beverages from plant origin, which have nutritional commercial appeal in the health aspects, as no animal fats and high mineral contents. Thus, we aimed to determine water-soluble extract formulations, by technological processes in pilot scale, of the Brazil nut, to realize proximate, microbiological, sensory and rheological characterization, of the drinks obtained, and evaluate the physical and chemical stability, physical and microbiological of the extracts in the presence and absence of light. The Brazil nuts extracts had total solids, protein, fat and minerals, high, and can be considered products with high nutritional value. The Brazil nut extracts showed a pseudoplastic fluid non-Newtonian behavior. The extracts developed with preservatives had useful life of at least twenty-one days. Was unable to establish a relationship between the stability of the Brazil nut extract and the light incidence. The research of the water-soluble extract of Brazil nut can contribute with information to the use of this product in human meal. / A amêndoa in natura é a principal forma de consumo da castanha-do-Brasil, entretanto, coprodutos como o extrato hidrossolúvel podem ser explorados comercialmente. Extratos hidrossolúveis são bebidas de origem vegetal, que possuem apelo comercial nutricional, quanto aos aspectos de saúde, como ausência de gorduras animais e altos teores de minerais Desta forma, objetivou-se determinar formulações de extrato hidrossolúvel, mediante processamento tecnológico em escala piloto, de castanha-do-Brasil, realizar a caracterização centesimal, microbiológica, sensorial e reológica das bebidas obtidas e avaliar a estabilidade físico-química, física e microbiológica dos extratos na presença e na ausência de luz. Os extratos de castanha-do-Brasil apresentaram teores de sólidos totais, proteínas, lipídeos e minerais elevados podendo ser considerados produtos de alto valor nutricional. Os extratos de castanha-do-Brasil apresentaram comportamento de um fluido não-newtoniano pseudoplástico. Os extratos elaborados com conservantes tiveram vida útil de, no mínimo, vinte e um dias. Não foi possível estabelecer uma relação entre a estabilidade do extrato de castanha-do-Brasil e a incidência de luz. O estudo do extrato hidrossolúvel de castanha-do- Brasil pode contribuir com informações para a utilização deste produto na alimentação humana.

O fósforo (P) que é um nutriente pouco disponível em solos tropicais devido a sua deficiência natural e também por causa da imobilização do mesmo em constituintes do próprio solo, formando fosfatos insolúveis e assim indisponíveis as plantas. A solubilização destes fosfatos inorgânicos é uma estratégia para aumentar a disponibilidade deste nutriente no solo. Uma forma seria a utilização de microrganismos solubilizadores de P que deixam este nutriente disponível às plantas. Desta forma, o presente trabalho teve como objetivos: (i) avaliar o crescimento do cafeeiro em função das fontes e doses de P2O5; (ii) determinar o fósforo disponível e (iii) avaliar o estado nutricional do cafeeiro, em função da fonte e dose de P2O5. O desenvolvimento das mudas de cafeeiro é superior com o uso de fonte de P solúvel, em relação à fonte de solubilidade gradual, independentemente da dose. A determinação da capacidade de substituição da fonte solúvel pela fonte de solubilidade gradual depende do tempo de reação no solo, cuja máxima equivalência é igual a 84 %, aos 180 dias após a aplicação do fertilizante (MSF). Em solos com teor de P disponível suficiente para a cultura do cafeeiro é viável a substituição de uma fonte solúvel (SFS) por outra de baixa solubilidade associada à micro-organismos (MSF). / Phosphorus (P) which is a little available nutrient in tropical soils due to their disability and also because natural impoundment of the same constituents in the soil itself, forming insoluble phosphates and thus unavailable to plants. The solubilization of inorganic phosphate is a strategy to increase the availability of this nutrient in the soil. One way would be to use P-solubilizing microorganisms that make nutrients available to plants that. Thus, this study aimed to: (i) evaluate the growth of coffee as a function of the sources and levels of P2O5, (ii) determine the available phosphorus and (iii) assess the nutritional status of coffee, depending on the source and dose of P2O5. The development of coffee seedlings is higher with the use of soluble P source, in relation to the source of gradual solubility regardless of dose. The determination of the replacement capacity of the water soluble source of gradual solubility depends on the reaction time in the soil, whose maximum equivalence is equal to 84% at 180 days after fertilizer application (MSF). In soils with a sufficient level of available P for the cultivation of coffee is feasible to replace a water soluble (SFS) for another low solubility associated with micro-organisms (MSF).

The presence of pathogens in semen can compromise the outcome of assisted reproductive treatment, together with the possibility of the female partner or offspring becoming infected. This is cause for concern, especially in South Africa with a high prevalence of HIV-1. Most of these infected individuals are in their reproductive years with the desire to have their own genetically related children. Therefore, assisted reproductive treatment with effective risk reduction procedures, such as semen processing for the elimination of these pathogens is crucial. However, during sperm preparation by standard discontinuous density gradient centrifugation, the supernatant is aspirated to allow access to the purified sperm pellet. Pathogens from the upper layers can adhere to the inside surface of the test tube and flow down to re-infect the purified sperm sample. The use of a centrifuge tube insert may prevent the re-contamination of sperm samples after discontinuous density gradient centrifugation. Furthermore, seminal pathogens can bind specifically or non-specifically to spermatozoa, rendering semen decontamination procedures ineffective. Serine proteases, such as trypsin, have been demonstrated to effectively inactivate viruses and to break pathogen-sperm bonds. However, the addition of a protease to density gradient layers during semen processing could have a negative impact on sperm parameters. This research was therefore aimed towards the determination of: i) The effect of semen processing with trypsin and trypsin inhibitor on sperm parameters. ii) The prevalence of various bacteria in semen samples from men attending the Reproductive and Endocrine Unit at Steve Biko Academic Hospital. iii) The effectiveness of semen processing by discontinuous density gradient centrifugation with a centrifuge tube insert, for the elimination of some of the most prevalent bacteria, white blood cells and in vivo derived HIV-1. Evaluation of sperm parameters after semen processing indicated that trypsin and trypsin inhibitor did not have an impact on sperm mitochondrial membrane potential, vitality, motility and zona binding potential, or acrosin activity, respectively. Seminal bacteria were highly prevalent in patients wishing to participate in the Unit’s assisted reproductive program, with 49.5% of semen samples presenting with positive bacterial cultures. Semen processing by means of discontinuous density gradient centrifugation with the tube insert, eliminated significantly more in vitro derived (spiked) bacteria and white blood cells from semen compared to processing without the insert. Furthermore, the semen decontamination procedure was effective in removing HIV-1 RNA from 100% of samples and proviral DNA from 98.1% of semen samples from HIV-1 sero-positive patients. The effectiveness of discontinuous density gradient centrifugation for the elimination of seminal pathogens could, therefore, be improved by the addition of trypsin to the upper density layer, without supplementing the bottom layer with trypsin inhibitor. Additionally, semen decontamination efficiency could also be improved by the prevention of re-contamination of processed sperm samples by the utilization of a tube insert during discontinuous density gradient centrifugation. / Thesis (PhD)--University of Pretoria, 2014. / gm2014 / Obstetrics and Gynaecology / unrestricted

Human immunodeficiency virus (HIV) infection has reached epidemic proportions in South Africa. The availability of highly active anti-retroviral therapy (HAART) prolongs life in HIV-infected persons, who may subsequently present with chronic manifestations of HIV-infection. The respiratory morbidity attendant to HIV-infection, even in the presence of HAART is high, the aftermath of which is lung tissue destruction and bronchiectasis. As a consequence of the political decision not to offer HAART to HIV-infected children, a number of children in South Africa have been left with severe consequences of uncontrolled HIV-infection. Bronchiectasis is one of those and because children with this devastating condition were numerous in the Pretoria region, the author and her colleagues began a Chronic Lung Disease Clinic in that region. This prompted the idea of investigating both the epidemiological profiles of these children and an attempt to intervene with both standard bronchiectasis guideline care and the use of a form of therapy commonly employed in other forms of bronchiectasis. This thesis explores those ideas. Important new and novel findings that were consequent were; that bronchiectasis is diagnosed late in HIV-infected children at a mean age of 6.9 years. The predominant organisms cultured from the airways are Haemophilus influenzae and parainfluenzae in 49% of samples. Pseudomonas aeruginosa (PA), common in cystic fibrosis (CF)-bronchiectasis is an uncommon pathogen in HIV-related bronchiectasis; isolated in only 2% of specimens. Tuberculosis (TB), at least as reported, is a significant antecedent of bronchiectasis, reported in 48.5%of children. A further 21.2% of the patients had received more than two courses of anti-TB treatment. However, proof of TB infection has been lacking. Respiratory morbidity is significant with the mean forced expiratory flow in one second (FEV1) of 53%, in this cohort at the time of presentation. Thirty-six percent of all children were exposed to environmental tobacco smoke, although this was not correlated with disease severity or HIVdisease progression. There is elevation of immunoglobulins in HIV-related bronchiectasis, with a mean IgE of 79 kU/l. This was not, though, associated with HIV disease progression as previously described in adult studies, nor with the presence of allergic bronchopulmonary aspergillosis (ABPA). The elevation in IgE was also not associated with an elevation of T helper-2 mediated cytokines, confirming the lack of association with atopy. The predominant cytokine, identified is interleukin (IL)-8, both systemically and locally (in airway secretions). There was elevation of other T helper-1 driven cytokines, reflecting an ability to mediate adequate inflammatory responses, which was independent of the level of immunosuppression. With the presence of HAART, there was a decline in the pro-inflammatory cytokines over time, which may be attributed to the ongoing effect of HAART that ties in to, or goes beyond the restoration of T cell numbers. Soluble triggering receptor expressed on myeloid cells (sTREM), an innate immune marker, is elevated in children with HIV-related bronchiectasis when compared to a control group of children with cystic fibrosis-related bronchiectasis. sTREM is not associated with the presence of exacerbations and the level of immunosuppression. The use of an anti-inflammatory drug erythromycin also did not impact the sTREM values. There was also no relationship between sTREM and pro and antiinflammatory cytokines and chemokines. Fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET) could not reliably predict the presence of pulmonary exacerbations. Its diagnostic value was limited to identifying disease activity in acute pneumonia. 18F-FDG PET also had no significant correlation with CRP, inflammatory cytokines or markers of HIV disease activity. In a randomised controlled trial of erythromycin, a cost-effective immunomodulatory drug, compared to placebo, erythromycin was ineffective in reducing the number of pulmonary exacerbations. Erythromycin also failed to demonstrate any effect on systemic and local pro- and anti-inflammatory cytokines/chemokines. With access to anti-retroviral therapy, airway clearance, nutritional rehabilitation and vigilant follow up there was an improvement in pulmonary function parameters and stability of the degree of bronchiectasis that we propose is probably in keeping with an organ system disease modifying effect that may be, an as yet, undefined and undescribed byproduct of HAART. / Thesis (PhD)--University of Pretoria, 2012. / Paediatrics and Child Health / unrestricted

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2007. / Biogenic amines are nitrogenous compounds of low molecular weight found in most fermented foods, including wine. These biologically produced amines are essential at low concentrations for normal metabolic and physiological functions in animals, plants and micro-organisms. However, biogenic amines can have adverse effects at high concentrations and pose a health risk for sensitive individuals. Symptoms include nausea, hot flushes, headaches, red rashes, respiratory distress and fluctuations in blood pressure. A number of countries have implemented upper limits for histamine in food and wine. This development has already started to threaten commercial export transactions and may become more serious in the near future, especially in the competitive wine industry of today. The most important biogenic amines in wine include histamine, tyramine, putrescine, cadaverine and phenylethylamine which are produced from the amino acids histidine, tyrosine, ornithine, lysine and phenylalanine respectively. Biogenic amines are mainly produced in wine by microbial decarboxylation of the corresponding precursor amino acid. It may be produced by yeast during alcoholic fermentation, by lactic acid bacteria during malolactic fermentation, or potentially by spoilage microbes such as acetic acid bacteria and Brettanomyces. However, lactic acid bacteria are widely accepted as the main causative agents. Inoculation with commercial malolactic fermentation starter cultures that do not possess the relevant decarboxylase genes may inhibit the growth and activity of decarboxylase positive indigenous bacteria and as such control the production of biogenic amines in wine. In this study it was shown that co-inoculation of malolactic starter cultures together with alcoholic fermentation could reduce the incidence of biogenic amines in wine compared to conventional inoculation protocols; presumably because undesirable activities were restrained at an earlier stage during co-inoculation. It was also indicated in this work that in some cases the effect of co-inoculation on biogenic amine reduction may only be visible after a period of ageing. The frequency of biogenic amine occurrence in wines aged for a short period was generally higher in the presence of fermentation lees than in its absence. This work also included a preliminary investigation into the contribution of commercial wine yeast starter cultures to biogenic amine production. Diamines and polyamines (putrescine, spermidine and cadaverine) were produced to variable extents by all yeasts with very little or no production of physiologically important biogenic amines (histamine, tyramine and phenylethylamine). Another objective of this study was to evaluate the influence of common winemaking practices on biogenic amine production under winemaking conditions. We have shown that biogenic amine production by lactic acid bacteria could be influenced, amongst others, by the presence of precursor amino acids in the grape must or wine, the time of contact between juice or wine and grape skins, the time of contact between wine and yeast lees, the presence of microbial nutrients, wine pH, sulphite and ethanol levels, the phenolic composition of the wine and the number of decarboxylase positive lactic acid bacteria present in the wine. Lately, the wine industry is under increasing pressure to increase measures to ensure food safety and security and to eliminate any compound, present even in trace amounts that could reduce the wholesomeness of the wine. The need arises for a rapid and inexpensive method for quality control. In this study we investigated the potential to use Fourier transform infrared spectroscopy to rapidly screen for the presence of elevated levels of biogenic amines. This presents a novel method for the detection and quantification of total biogenic amines in wines.

Les écosystèmes côtiers sont des milieux complexes au sein desquels les communautés microbiennes, jouant un rôle majeur dans leur fonctionnement et leur maintien, s’adaptent et sont tolérantes à des conditions environnementales fluctuantes. En effet, au rythme des marées et de l'activité de la macrofaune, des oscillations oxie/anoxie influencent la composition et la dynamique des communautés microbiennes et par conséquent leur implication métabolique. Afin d’appréhender le devenir du pétrole dans ces écosystèmes, il est donc indispensable d’apporter des connaissances sur l’écologie des microorganismes intervenant dans son élimination, notamment dans des conditions oscillantes anoxie/oxie. Ainsi, ce travail de thèse a eu pour objectif de décrypter l’assemblage de communautés microbiennes hydrocarbonoclastesde sédiments intertidaux soumises à des oscillations anoxie/oxie en présence de pétrole lors d’une expérience en bioréacteurs. Les réponses écologiques des communautés bactériennes globales et de micro-organismes sulfato-réducteurs en conditions oscillantes ont pu être décrites en comparaison avec celles obtenues en conditions d’oxie ou d’anoxie permanentes, par l’analyse des données obtenues par séquençage haut-débit des gènes de l’ARN 16S et dsrB au niveau transcriptionnel. Ces études comparatives ont mis en évidence des profils écologiques en réponseaux conditions oscillantes, pouvant être répandus dans différents environnements marins côtiers. En réponse à ces conditions particulières, de nombreux microorganismes semblent avoir le potentiel à tolérer et/ou s’adapter aux différentes conditions d'oxygénation. Cette capacité d’acclimatation rapide des communautés bactériennes aux conditions oscillantes se sont accompagnées de capacités de dégradation équivalentes ou supérieures dans ces conditions par rapport à la condition d’oxie permanente montrant l’influence des oscillations anoxie/oxie sur le devenir du polluant dans les environnements pollués soumis à ces conditions. / Coastal ecosystems are complex environments in which microbial communities, playing a major role in their functioning and maintain, are tolerant and adapt to changing environmental conditions. Indeed, the tides and the macrofauna’s activity generate oxic/anoxic oscillations which influence the composition and dynamics of microbial communities and consequently their metabolic in volvement. To understand the fate of oil in these ecosystems, it is essential to provide knowledge on the ecology of microorganisms involved in these systems, taking into account anoxic/oxicoscillating conditions. Thus, this thesis aimed to decipher the organization of hydrocarbonoclastic microbial communities inhabiting intertidal sediments, when they are subjected to anoxic/oxic oscillations in an experiment in bioreactors with oil addition. Ecological responses of bacterial communities and sulfate-reducing microorganisms in oscillating conditions have been described comparing with those obtained with permanent oxic or anoxic conditions, using high-throughputsequencing analyses of the 16S rRNA and dsrB genes at the transcriptional level. These comparatives studies have highlighted ecological profiles in response to the oscillating conditions, which can be prevalent in different coastal marine environments. In response to these particular conditions, many organisms seem to have the potential to tolerate and / or adapt to the different conditions of oxygenation. This rapid acclimation capacity of bacterial communities tothese changing conditions have been accompanied by equivalent or greater degradation capacity under these conditions compared to the permanent oxic condition, showing the influence of the anoxic/oxic oscillations on the fate of pollutant in environments subjected tothese conditions.

Les cheminées et sédiments hydrothermaux actifs du Bassin de Guaymas (Mexique) hébergent diverses communautés microbiennes présentant différents métabolismes, y compris ceux impliqués dans les cycles biogéochimiques du soufre et du fer. Il est établi, que, dans ces écosystèmes dynamiques, les micro-organismes qui dépendent pour leur croissance des substrats présents dans leur environnement pourraient à leur tour, affecter localement la composition du fluide hydrothermal et la minéralogie des cheminées, la composition des sédiments, en favorisant la dissolution et/ou la précipitation de certaines phases minérales. Pour étudier ces interactions procaryotes-biotopes, et établir des liens entre la structure, l’activité et les signatures isotopiques des communautés microbiennes et les caractéristiques physico-chimiques des systèmes hydrothermaux du Bassin de Guaymas, une approche pluridisciplinaire mettant en oeuvre des techniques de microbiologie, de géochimie et d’isotopie, lors des cultures d’enrichissements en bioréacteur et des études de colonisation de substrats basaltiques a été réalisée. Ces travaux ont permis : 1) de caractériser la diversité des micro-organismes de différents compartiments de l’écosystème hydrothermal (cheminée et sédiments) du Bassin de Guaymas par des approches culturales et moléculaires ; 2) de décrypter le fonctionnement des cycles biogéochimiques du soufre et du fer en mettant en évidence la présence simultanée, à haute température et en anaérobiose, de micro-organismes sulfo-réducteurs, sulfato-réducteurs, sulfo-oxydants mais également ferri-réducteurs et ferro-oxydants ; et 3) de mieux comprendre les interactions procaryotes-minéraux-fluide en soulignant le rôle des microorganismes dans la modification des conditions environnementales, la formation de minéraux ainsi que leur rôle direct ou indirect dans les fractionnements des isotopes du Fer et Soufre. Ces études ont donc permis de montrer l’importance des interactions croisées entre les différents composantes : communautés microbiennes, le fluide (fluide hydrothermal, eaux interstitielles des sédiments, eau de mer) et les structures minérales des écosystèmes hydrothermaux. / Active hydrothermal chimney and sediments of the Guaymas Basin (Mexico) host various microbial communities with different metabolisms, including those involved in biogeochemical cycles of sulfur and iron. It is established that, in these dynamic ecosystems, microbial activity depends on the availability of substrates in their environment and that prokaryotes could, in return locally affect the composition of the hydrothermal fluid and mineralogical composition of the chimney or sediment, by mediating the dissolution and / or precipitation of some mineral phases. In order to study these prokaryotes-biotope interactions, and establish links between the structure, the activity and the isotopic signatures of microbial communities with the physico-chemical characteristics of hydrothermal systems of Guaymas Basin, a multidisciplinary approach based on the implementation of microbiology, geochemistry and isotope technics was performed using enrichment cultures in bioreactors and the study of the colonization of basaltic substrates. This work led to: 1) characterize the diversity of microorganisms in different hydrothermal compartments (chimney and sediments) of the Guaymas Basin using both cultural and molecular approaches; 2) to decrypt the functioning of sulfur and iron biogeochemical cycles, by highlighting the occurrence, at high temperature and anaerobic condition, of sulfur-reducing, sulfate-reducing, sulfur-oxidizing and also iron-reducing and iron-oxidizing prokaryotes ; and 3) to better understand the prokaryote-mineral-fluid interactions by pointing out the role of microorganisms in environmental condition changes, mineral precipitation and their direct or indirect role in iron and sulfur isotope fractionation. Thus these studies have demonstrated the importance of the cross-interactions between the different hydrothermal components: microbial communities, fluids (hydrothermal fluid, sediment pore water, sea water) and mineral structures.