Characterizing the microbial community involved in anaerobic digestion of lipid-rich wastewater to produce methane gas

This study attempted to characterize the microbial community and its role in anaerobic digestion of lipid. Reactors were fed semi-continuously with three related substrates, oil and its degradation intermediates (glycerol and long chain fatty acids (LCFAs)), with a stepwise increase in organic loading rate for 90 days. Microbial community analysis using next-generation sequencing (NGS) with the MiSeq Illumina platform revealed that Anaerolineaceae was the most dominant group of bacteria in all experiments, whereas Clostridium, Desulfovibrio, Rikenellaceae, and Treponema were observed characteristically in glycerol degradation and Leptospirales, Synergistaceae, Thermobaculaceae and Syntrophaceae were seen with high abundance in LCFA and oil mineralization. Furthermore, it was discovered that Methanosaeta was the most dominant archaea. The role of these microorganisms in the methane production from oil was estimated by comparing the microbial groups in the fermentation using three substrates, and a hypothetical pathway of the methane production was proposed. •Three related substrates, cooking oil, glycerol, and LCFA, were anaerobically digested.•Anaerolineaceae and Methanosaeta were dominant for all three substrates.•Clostridium, Desulfovibrio, Rikenellaceae, and Treponema favored glycerol.•Synergistaceae, Thermobaculaceae and Syntrophaceae favored oil and LCFAs.•Roles of microorganisms in the methane production from oil was hypothesized.