Bathyarchaeia, as one of the most abundant microorganisms on Earth, play vital roles in the global carbon cycle. However, our understanding of their origin, evolution, and ecological functions remains poorly constrained. Here, we present the largest dataset of Bathyarchaeia metagenome assembled genome to date and reclassify Bathyarchaeia into eight order-level units corresponding to the former subgroup system. Highly diversified and versatile carbon metabolisms were found among different orders, particularly atypical C1 metabolic pathways, indicating that Bathyarchaeia represent overlooked important methylotrophs. Molecular dating results indicate that Bathyarchaeia diverged at ~3.3 billion years, followed by three major diversifications at ~3.0, ~2.5, and ~1.8 to 1.7 billion years, likely driven by continental emergence, growth, and intensive submarine volcanism, respectively. The lignin-degrading Bathyarchaeia clade emerged at ~300 million years perhaps contributed to the sharply decreased carbon sequestration rate during the Late Carboniferous period. The evolutionary history of Bathyarchaeia potentially has been shaped by geological forces, which, in turn, affected Earth’s surface environment.
Fig. 1. The newly improved taxonomy and subgroup assignment of the class Bathyarchaeia.
(A) Phylogenomic affiliation of 304 representative Bathyarchaeia MAGs refined from publicly available databases and our laboratory datasets based on a concatenated alignment of 122-archaeal marker proteins implemented in GTDB-Tk by using IQ-TREE2 with LG+F+R10+C60 model and Shimodaira Hasegawa–like approximate likelihood ratio test with 1000 bootstrap replicates (bootstrap higher than 0.9 are shown with black dots). The colored background and outer rings denote the eight proposed orders of class Bathyarchaeia, and the inner black and gray rings represent the whole class Bathyarchaeia and phylum Thermoproteota, respectively. The number of MAGs used in the phylogenetic analysis is listed under the name for each taxonomic lineage. (B) Taxonomic assignment of subgroups for the representative Bathyarchaeia MAGs with 16S rRNA genes. The phylogenetic tree was constructed with subgroup-classified sequences from Zhou et al. as a reference by using RaxML 8.2.12 with -m GTRGAMMA -N autoMRE and 1000 bootstrap replicates (fig. S2).
Link: www.science.org/doi/full/10.1126/sciadv.adf5069