Traditionally, methanogenic degradation of complex organic matter requires the syntrophic metabolism between bacteria and archaea. The study used stable-carbon isotope-labeled culture, metagenome, and metatranscriptome sequencing and high-resolution mass spectrometry analysis to confirm that a novel single methanogenic archaeal species (Candidatus Methanoliparum) could directly complete the process of long-chain alkyl hydrocarbons degradation to methane production through β-oxidation and Wood Ljungdahl and methanogenesis pathways. Thus, the fifth methanogenic pathway (alkylthrophic methanogenesis) is proposed. Our research expanded the knowledge of the biogeochemical carbon cycle and provided a theoretical basis for developing carbon emission reduction technologies and underground biogas projects.

CARD-FISH (green, Candidatus Methanoliparum; red, bacteria)

Methanogenesis pathway of n-hexadecane degradation by single archaea