Molecular analysis of methanogen populations and their interactions within anaerobic sludge digesters

AbstractKnowledge of archaeal population structure, function and interactions is of great interest for a deeper understanding of the anaerobic digestion step in wastewater treatment process, that represents a bottle neck in the optimization of digesters performance. Although culture-independent techniques have enabled the exploration of archaeal population in such systems, their population dynamics and interactions still require further investigation. In the present study, 2646 almost full archaeal 16S rRNA gene sequences retrieved from 22 anaerobic digesters located worldwide were analyzed and classified into 83 Operational Taxonomic Units (OTUs) for Euryarchaeotes and 2 OTUs for Crenarchaeotes. Among the Euryarchaeotes, Methanosarcinales represent the predominant archaeal population (47.5% of total sequences), followed by the ARC I (WSA2) lineage (25.3%), Methanomicrobiales (19.9%) and Methanobacteriales (1.9%). Theses lineages are predominant in nine, five, two and one digesters respectively. However, ...