Differences in microbial key players in anaerobic degradation between biogas and sewage treatment plants

Biogas production in biogas plants (BPs) and sewage treatment plants (STPs) of industrial and municipal waste, respectively, is principally based on the same metabolic processes. Process parameters, bacterial and archaeal community composition of 16 BPs and 10 STPs with large-scale biogas production were analyzed by 16S rRNA gene amplicon sequencing to assess a common core microbiome. Both community compositions differed between plant types, and those of BPs were significantly affected by substrate, whereas STP community compositions were governed by pH. Operational taxonomic unit (OTU) richness and diversity were significantly higher in STPs compared to BPs. Microbial network analysis of the overall bacterial and archaeal community composition identified 39 generalistic OTUs for BPs and only 11 for STPs, respectively. Our findings indicate that BPs were less complex with various common key players in all plants whereas STPs were composed by a more plant-specific microbial network. Assignment of each generalistic OTU to one or more steps of anaerobic degradation corresponded to well-known syntrophic interactions as well as to potential but unknown interactions.