Methanogenic degradation of crude oils: from biological discovery to geochemical indications

Methanogenic degradation of crude oil hydrocarbons is a common process in subsurface oil reservoirs. This process is known to occur either through syntrophic cooperation among different microbial consortia—such as bacteria and methanogens or archaea and methanogens—or via a single archaeon, designated as an alkylotrophic methanogen. Here, I report the biochemical characteristics of alkyl-coenzyme M reductase (ACR), the key enzyme responsible for alkylotrophic methanogenesis. I also present the stable carbon isotope fractionation associated with this process, which may help identify a novel microbial source of secondary microbial gas (SMG). These findings advance our understanding of carbon biogeochemical cycles in the deep subsurface and provide new insights into microbial enhanced energy recovery (MEER) from residual oils in depleted petroleum reservoirs.

CV: Prof. Dr. Lei Cheng is a researcher (Professor) at the Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences (AGIS-CAAS), and the Biogas Institute of the Ministry of Agriculture and Rural Affairs in Chengdu (BIOMA). He received his degrees from Anhui Normal University (B.Sc., 2000–2004), the Graduate School of the Chinese Academy of Agricultural Sciences (M.Sc., 2004–2007), and China Agricultural University (Ph.D., 2008–2011).

Dr. Cheng’s research focuses on methanogenic degradation of crude oil hydrocarbons. He developed a platform for the long-term preservation and high-throughput screening of anaerobic microorganisms, proposed a novel strategy for directional isolation of anaerobic microorganisms by regulating growth curves (Trends in Microbiology, 2025), and established a “cocktail” method for isolating methylotrophic archaea (Nature Protocols, 2025).In collaboration with several research teams, Dr. Cheng has isolated the first non-euryarchaeotal methanogen (Nature, 2024), demonstrated the complete degradation of oil in a single methanogen (the fifths methanogenesis pathway) (Nature, 2022), and discovered interspecies methanol transfer between bacteria and methanogens (Nature, 2025).