Single cell genomic study of candidatus Atribacteria JS1 lineage predominant in marine sediments of the Ross Sea, Antarctica

Abstract

Candidate phylum Atribacteria JS1 lineage is among the predominant members in anoxic subseafloor environments, especially in methane-rich sediments. However, the metabolic potential and biogeochemical role of this phylum have remained elusive due to the lack of axenic culture representatives. To understand the metabolic potential and ecological funtion of candidate phylum Atribacteria JS1 lineage, single cell genomic approach was applied. From the marine sediment at 40 cmbsf of the Ross Sea with 38.9% portion of JS1, 18 single cell amplified genomes considered to be a single species and consistent with the dominant Atribacteria JS1 species in that environment were obtained. The composite genome with the highest genome coverage (2.3Mb) encoded redundant ABC transpoters for amino acid, peptide, and saccharide, complete sets of enzymes in glycolysis and the Wood-Ljungdahl pathway for CO2 fixation. Atribacteria JS1 in the Rose Sea was predicted to be homoacetogenic bacteria, which is capable of growing on H2/CO2 or CO2, and have heterotrophic lifestyle by fermenting various carbon sources. The presence of the Wood-Ljungdahl pathway to run in reverse showed the possibility of Atribacteria JS1 as a syntrophic acetate-oxidizer with hydrogenotrophic methanogens which explains their predominance in anoxic methane-rich sediments. Genomic analysis of Atribacteria JS1 provided functional potential of this uncultivated but considered to be very important group in carbon cycling.