Microbiome of anaerobic digesters in municipal wastewater treatment plants. sludge metagenome

Anaerobic digestion (AD) is a promising biotechnology that simultaneously achieves waste treatment and energy recovery simultaneously. For the purpose of improving operation performance, previous researches have attempted to define the core microbiota of AD, but due to the complexity of the microbial ecology and limited sampling size of the diverse type of digesters, our understanding remains insufficient. In this study, we performed a comprehensive microbial community survey by using 16S rRNA gene-based sequencing of 148 digester sludge samples from 90 full-scale digesters at 51 municipal wastewater treatment plants from North America, Europe, and East Asia. Among the samples, eight different types of community structures were identified, among which the largest one could serve as a model structure of digester microbiome. Relatively mild community changes were induced by moderate temperature fluctuation, while drastic community changes were caused by pretreatment, high salinity and high temperature. Within each type, we identified the signature microbial populations that were associated with the operating conditions. By performing pairwise comparisons between the microbiomes in the feed to and within the digesters, microbial populations that were likely resides as result of incomplete digestion were identified. Overall, this study elucidates of microbial ecology in AD and provides a basis for further investigations into the functions of poorly defied microorganisms, which could ultimately enable improvement of digestion performance.