Microbial Community Structures in Terrestrial Subsurface Sediments from the Southern Kanto Plain, Japan

Microbial community structure reflects the surrounding natural environment and changes to that environment. Although the subsurface at 5–100 m depth is important for human activities and there are potential risks of environmental pollution in this region, there have been only a few reports of subsurface microbial community structures in terrestrial areas. We investigated the diversity and community compositions of <i>Bacteria</i> and <i>Archaea</i> in boring cores collected from various depths at three different sites in the southern Kanto Plain, Japan. The results of 16S rRNA gene amplicon sequencing using MiSeq showed that the microbial community composition varied with the geological unit. <i>Proteobacteria</i> (<i>Alphaproteobacteria</i> and <i>Gammaproteobacteria</i>) were dominant members within sediments accumulated during the Pleistocene in the Musashino Upland. In contrast, <i>Acidobacteria</i> and <i>Chloroflexi</i> characteristically appeared in the Holocene layers of the Arakawa Lowland. These data suggest that the subsurface microbial composition is controlled by the geological features of the sediments.