Long-term temporal dynamics of total and potentially active microbiota affect the biogas quality from the anaerobic digestion of vinasse in a pilot-scale hybrid anaerobic reactor

The microbiota was evaluated through a time series of the 16S rrna gene in a pilot-scale Hybrid Anaerobic Reactor treating vinasse. The microbial composition, evenness and diversity differed between the DNA and cDNA, the latter showing a better response for %CH4 along monitoring of the microbiota. Moreover, the microbial composition and richness were distinct between the reactor's compartments, possibly contributing to the COD removal in the sludge blanket. The abundant Methanospirillum, Methanomassiliicoccaceae, Bacteroidetes-vadinHA17, Paludibacteraceae-H1, Prolixibacteraceae, Ruminococcaceae, Syntrophobacter and Desulfovibrio contributed to the %CH4, as well as the redundancy of fermentation and hydrogenotrophic and methylotrophic methanogenesis, and the evenness and diversity of potentially active microbiota and metabolisms. The microbial changes after the middle of reactor's operation required new adaptations and impacted the biogas quality, but did not affect COD removal. This study brings important knowledge about the microbial temporal dynamics, plasticity and contribution to the anaerobic digestion in pilot-scale reactors.