Estudo da diversidade microbiana em reator UASB aplicado ? degrada??o de azocorantes.

Este estudo investigou as popula??es microbianas potencialmente envolvidas na degrada??o do corante azo Drimaren Azul HF-RL em um reator UASB operado em escala de bancada ? temperatura ambiente e sob condi??es de alimenta??o distintas (por exemplo, presen?a e aus?ncia de glicose e/ou extrato de levedura). Para este projeto, foram aplicadas duas diferentes abordagens experimentais. A primeira foi baseada no isolamento de culturas microbianas associadas ? t?cnica de identifica??o molecular, a fim de investigar a capacidade anaer?bia de culturas puras para realizar descolora??o. A segunda foi baseada na t?cnica molecular PCR-DGGE empregada para investigar a riqueza e din?mica dos micro-organismos predominantes presentes no UASB durante a degrada??o de corantes azo. Os resultados obtidos com os procedimentos de enriquecimento e isolamento permitiu a identifica??o de uma cepa anaer?bica caracterizada como bacilo Gram-negativo e que pertence ao grupo formado filogeneticamente por Azospira oryzae, Declorosoma sp. e Azoarcus sp. No entanto, nenhum processo de descolora??o foi observada quando esta cepa foi cultivada em cultura pura. A PCR-DGGE mostrou que a composi??o de micro-organismos mudou desde o in?cio at? o fim da opera??o do reator e juntamente com a perda de s?lidos totais (ST), os resultados sugerem a adapta??o da biomassa. A efici?ncia de remo??o de cor foi maior na presen?a de 500mg/L de extrato de levedura, por?m n?o houve diferen?as significativas nos perfis microbianos que podem indicar a presen?a de uma biomassa especializada. Particularmente a metanog?nica acetocl?stica Methanosarcina parecia ser favorecida nos ?ltimos est?gios do reator UASB, provavelmente por ser mais adaptada do que Methanosaeta ? presen?a de azo corante e aminas arom?ticas. Portanto, os resultados sugerem que n?o h? um micro-organismo especializado envolvido na biodegrada??o de azo corante no reator UASB e, provavelmente, a alta efici?ncia na remo??o de cor foi devido a uma associa??o entre micro-organismos anaer?bios adaptados que produziram equivalentes redutores para a redu??o extracelular do corante azo mediada pelos compostos redox (por exemplo, riboflavina) presentes no extrato de levedura.This study investigated the microbial populations potentially involved in the degradation of azo Drimaren Blue HF-RL in a UASB reactor operated at bench scale at room temperature and under distinct feeding conditions of the reactor (e.g. presence and absence of glucose and / or yeast extract). For this project, it was applied to two different experimental approaches. The first was based on the isolation of microbial cultures associated with the molecular identification technique in order to investigate the ability of anaerobic pure cultures to perform decolorization. The second was based on molecular technique PCR-DGGE and was employed to investigate the diversity and dynamic of the predominant microorganisms present in the UASB during the azo dye degradation. The results obtained with enrichment and isolation procedures allowed the identification of one anaerobic strain characterized as Gram-negative rods and belonging to the phylogenetically cluster formed by Azospira oryzae, Declorosoma sp. e Azoarcus sp. However no discoloration process was observed when this strain was cultivated in pure culture. The PCR-DGGE showed that composition of microorganisms changed from the beginning to the end of reactor operation and together with the loss of total solids (TS) results suggest biomass adaptation. The efficiency of color removal was highest in the presence of 500mg/L of yeast extract, however no significant differences in the microbial profiles that could indicate the presence of a specialized biomass. Particularly the aceticlastic methanogen Methanosarcina seemed to be favored in the last stages of the UASB reactor probably by being more adapted than Methanosaeta to the presence of azo dye and aromatic amines. Therefore the results suggest that there is no specialized microorganism involved in the biodegradation of azo dye in the UASB reactor and probably the high efficiency on color removal was due to an association between adapted anaerobic microorganisms which produced reducing equivalents for the extracellular reduction of the azo dye mediated by the redox compounds (e.g. riboflavin) present in the yeast extract