Microbiome digital signature of MCR genes – an in silico approach to study the diversity of methanogenic population in laboratory-developed and pilot-scale anaerobic digesters

Abstract

The production of biogas by anaerobic digestion (AD) of organic/biological wastes has a firm place in sustainable energy production. A simple and cost-effective anaerobic jar at a laboratory scale is a prerequisite to study the microbial community involved in biomass conversion and releasing of methane gas. In this study, a simulation was carried out using a laboratory-modified anaerobic-jar-converted digester (AD1) with that of a commercial/pilot-scale anaerobic digester (AD2). Taxonomic profiling of biogas-producing communities by means of high-throughput methyl coenzyme-M reductase α-subunit (mcrA) gene amplicon sequencing provided high-resolution insights into bacterial and archaeal structures of AD assemblages and their linkages to fed substrates and process parameters. Commonly, the bacterial phyla Euryarchaeota, Chordata, Firmicutes and Proteobacteria appeared to dominate biogas communities in varying abundances depending on the apparent process conditions. Key micro-organisms identified from AD were Methanocorpusculum labreanum and Methanobacterium formicicum. Spe-cific biogas production was found to be significantly correlating to Methanosarcinaceae. It can be implied from this study that the metagenomic sequencing data was able to dissect the microbial community structure in the digesters. The data gathered indicates that the anaerobic-jar system could throw light on the population dynamics of the methanogens at laboratory scale and its effectiveness at large-scale production of bio-methane. The genome sequence information of non-cultivable biogas community members, metagenome sequencing including assembly and binning strategies will be highly valuable in determin-ing the efficacy of an anaerobic digester.