Ambient and mesophilic phenol-degrading methanogenic consortia characterized by high throughput sequencing

Abstract

Two anaerobic semi-continuous bioreactors were operated at ambient (20oC) and mesophilic (37oC) conditions to treat phenol-containing wastewater for 193 days, achieving a maximum specific methanogenic activity of 200 and 283 mg CH4-COD g−1 VSS day−1, respectively. The high-throughput sequencing (HTS) analysis indicates that multiple syntrophic bacteria, such as Syntrophorhabdus, novel W22, Pelotomaculum and Moorella, were present but at quite different abundances under the ambient and mesophilic conditions. The co-occurrence of green sulfur bacteria Chlorobia, sulfate-reducing Desulfovibrio and Sulfurovum-like genera in the ambient consortia might be unfavourable for methanogenesis. The archaeal proportion in total bacterial and archaeal populations increased after enrichment, and Methanosaeta (instead of Methanosarcina in the seed sludge) became the most predominant methanogen. Overall, this HTS-based study reveals the high diversity of the microbial communities and poses initial insights into the complicated bacterial interactions involved in methanogenic phenol biodegradation.