Diversidade e prospecção de metagenoma microbiano em fermentadores de biogás produzindo H2

Abstract

Hydrogen appears to be the most promising candidate for the replacement of fossil fuel due to its potentially higher efficiency of conversion to usable power and no toxic emission production.The production of hydrogen from organic wastes is performed through the anaerobic digestion, making it an environmentally friendly alternative for satisfying future hydrogen demands.Nonetheless, the microorganisms and metabolic processes involved are far from being exhaustively characterized. In this work, samples of a domestic sewage treatment plant were analyzed in two complementary studies aiming at the characterization of its phylogenetic diversity and the description of new hydrogenases. The first one, combined the analysis of 16S rRNA and [FeFe]-hydrogenase (hydA) genes with statistical tools to estimate richness and diversity of the prokaryotic community at the phylogenetic and functional levels. Phylogenetic analysis showed that all archaeal sequences were affiliated with yet uncultured Euryarchaeota and that Proteobacteria were the most predominant and diversified phylogenetic group within the bacterial library. The putative hydA sequences were identified as hitherto undetected [Fe-Fe]hydrogenase gene sequences. Diversity statistical analysis confirmed a great richness and diversity of bacterial and hydA sequences retrieved from the sewage sludge sample. In the second approach, a fosmid metagenomic library was constructed and analyzed employing 454pyrosequencing technology, resulting in approximately 218 Mb of data. Three different classifiers applied allowed a broad overview of the most abundant taxonomic groups due to a huge number of metagenome reads remained unidentified. However, taxonomic analysis revealed Gammaproteobacteria and Deltaproteobacteria, respectively, as the most abundant classes,