MICROBIAL COMMUNITY ANALYSIS OF PERMAFROST SOIL IN CANADA USING PYROSEQUENCING

Abstract

Microbial community structure of permafrost soil was investigated by pyrosequencing analysis. The permafrost soil was collected from submerged shallow freshwater around Resolute, Canada (N, 74° 41' 177"

W, 94° 54' 458"). The freshwater seemed to exist temporary and oligotrophic. The soil color was gray. The number of bacterial sequences was 7,796 reads, and it was clustered 2,547 OTUs with 97% sequence similarity cutoff. Major phyla were Proteobacteria (37.7%), Bacteroidetes (30.0%), Firmicutes (9.1%) and Cyanobacteria (6.4%). Several OUTs occupied over 1% and shared high sequence similarity with previously reported bacteria: Anabaena solitaria 82 (AJ293105) which was isolated from a fresh water lake in Finland, Rhodoferax antarcticus (AF084947) which was isolated from an Antarctic microbial mat, uncultured bacteria isolated from sediment of a reservoir and rhizosphere of a plant of the genus Phragmites, and unclassified taxa of Bacteroidales, Sphingobacteriales, Clostridiales, Cytophagaceae, Flavobacterium and Geobacter. The number of archaeal sequences was 245 reads, and it was clustered 24 OTUs. The phylum Euryarchaeota was dominated (51.4%), followed with Thaumarchaeota (46.1%). Five dominant taxa shared high sequence similarity with previously reported archaea: methane producing Methanosarcina lacustris, uncultured methanogen originated from goat rumens, and uncultured archaea isolated from Minerotrophic fen peatland, uranium mining waste, and rhizosphere of the freshwater macrophyte Littorella uniflora. This study showed that bacteria exceeded archaea by far in number in this permafrost soil. Several bacteria occupied over 1% coexisted with diverse bacteria more than 2,500. On the other hand, five major archaea which may contribute to biogeochemical cycle were dominant.