[MIS17-P10] Isotopic gas and microbial analyses of gas hydrate-bearing core in subsea floor sediments,offshore Sakhalin
The GH-gas confirmed as thermogenic gas on the basis of Barnard plots, and including higher H2S and ethane than the other cores using principal component analysis of gas compositions. According to DNA-based microbial composition analysis, the Archaea abundance reduced along with the sediment depth. Under 20 cmbsf, MBG-B, MBG-D and Woesearchaeota (DHVEG-6) were dominated in Archaea. No methanogen was detected. Heterotrophic Chloroflexi and Candidate Atribacteria were major bacteria at a depth of 100 to 260 cm. It had been reported that Atribacteria decompose organic matters and generate ethanol and acids, by single cell genomics and metagenomics strategies. Since the low-molecules can be metabolized by methanogens, the Atribacteria-dominated bacteria composition may exhibit the possibility of methanogens, but methanogen was not detected. Low resolution of cloning-based DNA analysis might interrupt to detect methanogen. We, therefore, attempt to perform amplicon sequencing by Illumina the next generation sequencer.