Microbial consortia composition on the production of methane from sugarcane vinasse

Vinasse is a by-product from the ethanol industry and can be used for methane production through anaerobic digestion process driven by microbial consortia. The microorganisms involved must be known to obtain an ideal methane production. The present work evaluated the production of methane and byproducts from different ratios substrate/biomass (S₀/X₀), using sludge from an effluent treatment of the vegetable oil industry as inoculum in media containing vinasse. Also, the microbial community of the best methane production bioassay was characterized by high-throughput DNA sequencing. The following chemical parameters were evaluated: methanogenic activity, chemical oxygen demand, carbohydrate consumption, and production of volatile fatty acids. The highest methane production occurred at S₀/X₀ ratio of 1.5, which produced 59.78 mmol CH₄ L⁻¹. A great variety of microorganism genera was identified by high-throughput DNA sequencing, showing differences in the microbial consortia of the initial and final sampling times. At the final sampling point, the classes Bacteroidia (Porphyromonadaceae—OTU genera unknown 42.26% and Bacteroides genus 10.58%) and the class Betaproteobacteria (Proteobacteria-Comamonadaceae OTU) were identified as the dominant bacteria. The most abundant archaeal genera in the bioassay were Methanosaeta, Methanomassiliicoccaceae OTU vadinCA11, and Methanobacterium. The identification of the microorganisms of consortia involved in anaerobic digestion can collaborate on technologies to increase methane production through microbial isolation, bioaugmentation, and co-cultures.