Insight into microbial community diversity and composition of two-stage anaerobic digestion: Focusing methanogenic stage

This work characterized microbial community composition and diversity of the ‘methanogenic phase’ of a two-staged anaerobic sequence batch reactor(ASBR). The ASBR was operated for biogas production from abattoir wastewater, heterogeneous fruits-vegetables solid waste, and their combinations. The Metagenomic DNA of digestate from the ASBRs was extracted and amplified with sample-specific primers targeting the (V3-V4) hypervariable regions of the 16S rRNA gene. The 16S rRNA Amplicons were sequenced using the Illumina MiSeq. The overall microbial composition was influenced by the nature of substrates. The sequence analysis revealed that the methanogenic stage ASBRs were dominated by bacterial and archaeal members most closely related to Proteobacteria, Firmicutes, Planctomycetes, and Euryarchaeota. Out of identified methanogens genera, Methanosaeta and Methanosarcina were the most dominant. Compared to Methanosarcina, the unclassified spp. of a member of the Methanosaeta genus was the most dominant. This implied the Methanosaeta spp. were mainly responsible for the biomethanation of the substrates.