Distribution and phylogenetic diversity of cbbM genes encoding RubisCO form II in a deep-sea hydrothermal field revealed by newly designed PCR primers.

To investigate the phylogenetic diversity of putative chemolithoautotrophs possessing the RubisCO form II gene (cbbM) in various environments, we designed a new PCR primer set targeting this gene. The primer set was designed to cover more diverse and longer sequences of cbbM genes than those reported previously. We analyzed various samples (i.e., benthic sands, basement rocks, sulfide chimneys, vent fluids and overlying bottom seawater) collected in a deep-sea hydrothermal field of the Suiyo Seamount, Izu-Bonin Arc, Western Pacific, by PCR-based analysis using the designed primer set. Most of the cbbM phylotypes recovered from the liquid samples were related to those of the SUP05 group that belongs to the Gammaproteobacteria and includes putative sulfide-oxidizing chemolithoautotrophs. In contrast, the cbbM phylotypes recovered from the solid samples were related to environmental clones with low similarity (74-90%) and not closely related to the SUP05 group (69-74%). The cbbM phylotypes recovered from the liquid samples were different from those of the solid samples. Furthermore, the cbbM phylotypes recovered from the solid samples were different from each other. Our results expand knowledge of the phylogenetic diversity and distribution of putative chemolithoautotrophs possessing RubisCO form II cbbM genes in deep-sea hydrothermal fields.