title: Vertical stratification of subsurface microbial community composition across geological formations at the Hanford Site.
abstract: Microbial diversity in subsurface sediments at the Hanford Site 300 Area near Richland, Washington state (USA) was investigated by analysing 21 samples recovered from depths of 9-52 m. Approximately 8000 near full-length 16S rRNA gene sequences were analysed across geological strata that include a natural redox transition zone. These strata included the oxic coarse-grained Hanford formation, fine-grained oxic and anoxic Ringold Formation sediments, and the weathered basalt group. We detected 1233 and 120 unique bacterial and archaeal OTUs (operational taxonomic units at the 97% identity level) respectively. Microbial community structure and richness varied substantially across the different geological strata. Bacterial OTU richness (Chao1 estimator) was highest (> 700) in the upper Hanford formation, and declined to about 120 at the bottom of the Hanford formation. Just above the Ringold oxic-anoxic interface, richness was about 325 and declined to less than 50 in the deeper reduced zones. The deeper Ringold strata were characterized by a preponderance (c. 90%) of Proteobacteria. The bacterial community in the oxic sediments contained not only members of nine well-recognized phyla but also an unusually high proportion of three candidate divisions (GAL15, NC10 and SPAM). Additionally, 13 novel phylogenetic orders were identified within the Deltaproteobacteria, a clade rich in microbes that carry out redox transformations of metals that are important contaminants on the Hanford Site.
authors: Pacific Northwest National Laboratory, Biological Sciences Division, Richland, WA 99352, USA.
authors: Xueju
authors: X
authors: Lin
authors: David
authors: D
authors: Kennedy
authors: Jim
authors: J
authors: Fredrickson
authors: Bruce
authors: B
authors: Bjornstad
authors: Allan
authors: A
authors: Konopka
mesh_terms: D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000254:growth & development; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000254:growth & development; D001483:Base Sequence; D044822:Biodiversity; D020459:Genes, rRNA; D005844:Geology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S; D014861:Washington
chemical_list: D012336:RNA, Ribosomal, 16S