Metagenomic analysis reveals active Group II Mcr-encoding archaea in terrestrial geothermal springs, indicating non-euryarchaeal lineages play key roles in global methane cycling.
Key Points
To investigate the distribution, ecological roles, and evolutionary history of methyl-coenzyme M reductase (Mcr)-encoding archaea in terrestrial geothermal springs.
Performed metagenomic sequencing of 157 terrestrial geothermal springs in Tengchong, China.
Reconstructed and annotated 104 Mcr-containing metagenome-assembled genomes (MAGs).
Conducted metatranscriptomic profiling and phylogenetic analyses across varying temperature and pH regimes.
Reconstructed 90 Group II Mcr-encoding MAGs, predominantly Methanosuratincolia, which exceeded Group I euryarchaeotal MAGs in relative abundance across most spring samples.
Detected elevated transcriptional activity of methane-metabolism genes under extreme thermal (> 70 °C) and alkaline (pH > 9) conditions.
Identified hydrogenotrophic and heterotrophic pathways in Bathyarchaeia MAGs along with evidence of horizontal gene transfer with Methanonezhaarchaeia, supporting methylotrophic methanogenesis as ancestral among sampled Mcr-containing Thermoproteota.