Phylogenetic analysis of mcrA gene of methanogenic archaea

Abstract

Methane (CH4) is the forceful greenhouse gases, which produced from methanogens. The key enzyme for methane production is methyl-coenzyme M reductase (MCR). The q-subunit of MCR is encoded by mcrA gene. The mcrA gene was applied as a specific marker for study of methanogens diversity. The study was based on the collection of mcrA gene sequences. The gene sequences were obtained from genome database (GenBank). Phylogenetic tree was reconstructed using mcrA gene sequences. Methanopyrus kandleri (AE009439) was selected for an out group of the Bayesian analysis. The phylogeny was not only illuminated the evolution of mcrA gene but also represented the relationship between the methane production pathways and the habitats of the methanogens. Two lineages of methanogenic archaea were appeared on the consensus tree (group A and B). The group A methanogens contained two subgroups (subgroup A1 and A2). The group A methanogens possesses three methanogenesis pathways, which were hydrogeno-tropic, acetoclastic and C1-pathway. The group B methanogens were mostly thermophiles or hyper-thermophiles. Hydrogenotropic pathway was the main process for methanogenesis of the methano-gens group B.