Uso do sequenciamento de alto desempenho para caracterizar comunidades microbianas envolvidas na produção de metano e coprodutos a partir da digestão anaeróbia da vinhaça

Abstract

Vinasse is a residue resulting from the production of ethanol generated in large quantities in Brazil, and can be approved for biogas production. Several microorganisms act in the degradation of the vinasse to obtain biogas, and the study of microbial consortia is essential for optimization of the process. This work aimed to evaluate the production of methane and co-products from the vinasse, as well as to identify bacteria and archaea involved in the production of methane by high performance sequencing. Initially, the potential of enrichment of the inoculum in biogas production was verified. The methane production was evaluated with Zinder medium and Monteggia medium with and without acetate, and later it has tests with previous environment of the inoculum coming from the treatment plant of vegetable oil and vinasse. Concomitant experiments were carried out in a 5L reactor, with different samples (0,25; 0,5; 0,75; 1,0 ; 1,25; 1,5 and 1,7), in which gas samples were collected and liquid for analysis of methane production, volatile fatty acids, removal of COD and identification of microorganisms. It was found to be an addition of acetate to the nutrient media yielding the production of 5.9 mmol / CH 4 with Zinder medium. The bioassay without enrichment was highlighted according to the ratio S0/X0 = 1,5 which produced 12,48 mmol/CH4. In all bioassays, acetic, propionic and valeric acids were produced, and the highest acid production in relation to S0/X0=1,7 was obtained with enrichment in the inoculum environment, where 115mg.L -1 acetic acid, 195 mg.L1 of propionic acid and 154 mg.L -1 of butyric acid. A microbiota of the S0/X0=1.5 ratio showed a predominance of bacteria of the phyla Bacteroidetes (49.92%), Firmicutes (12,02%) and Proteobacteria (11,23%). The genera Bacteroides, OTU belonging to the Porphyromonadaceae Family; and archaea Methanobacterium, Methanosaeta and Methanosarcina were the predominant. Bacteroidetes (22,63%), Euryarchaeota (19,94%), and Firmicutes (16.33%) were the most important ones, with a larger scale (5L), a microbiota evaluated according to S0/X0 = 1,7; genus Methanosaeta (15%), microorganism of the family Porphyromonadaceae (13,54%) and Candidatus Cloacamonas, (9,36%) in the sample of the peak of production. As archaea found in the samples were: Methanobacterium sp., Methanomas sp., Methanosaeta sp., Methanomassiliicoccus sp, and microorganisms of the order Methanobacteriales. A vinasse showed great potential for methane production, and a wide diversity of microorganisms identified that help in the understanding and optimization of the process.