Metabolic pathway analysis based on high-throughput sequencing in a batch biogas production process

Using high-throughput sequencing technology based on 16S rRNA genes and the determination of abiotic factors, the metabolic pathways and microbial community dynamics were analyzed in a batch biogas fermentation process with pig manure as the feedstock at 15 °C. The results showed the followings. 1) The decomposition rate of cellulose and semi-cellulose were close to maximal level at day 40.2) At the phylum level, the most dominant bacteria and archaea were Firmicutes and Euryarchaeota respectively. 3) Most dominant species maintained predominant positions even though the microbial community structure changed throughout the fermentation; in particular, the abundance of dominant bacteria increased when the biogas fermentation peak appeared. 4) The four most dominant bacterial species were involved in hydrolysis of cellulose and semi-cellulose. 5) The metabolic pathway and microbial composition in hydrolysis and acidogenesis are very similar, but those in acetogenesis and methanogenesis are different to some extent. The acetogenesis pathway almost disappeared between days 24 and 72.6) Even though the overall microbial communities consisted of >400 species, the key bacteria and archaea for hydrolysis, acidogenesis, acetogenesis, and methanogenesis comprised 13–15 species, and most of these species had high similarity (≥97%) to culturable strains.