Community structure of archaea from deep-sea sediments of the South China Sea.

Using the archaeal 16S rRNA gene, we determined the community structures of archaea of subseafloor sediments (∼9-11 m below seafloor) from two geographically distant cores (MD05-2896, south, water depth 1,657 m; MD05-2902, north, water depth 3,697 m) in the South China Sea. Euryarchaeota accounted for 61.4% of total archaeal clone libraries at MD05-2896 and 56.2% at MD05-2902. At both locations, the Euryarchaeota-related sequences were dominated by Marine Benthic Group D, Terrestrial Miscellaneous Eryarchaeotal Group, and South African GoldMine Euryarchaeotal Group; the Crenarchaeota-related sequences were dominated by Marine Benthic Group B, Marine Group I, pSL12, and C3. The community structure showed no significant difference with depth at each location, suggesting the lack of stratification of archaeal populations in the deep-sea marine sediments in the South China Sea. On the other hand, the community structure is significantly different between the two sites, which may be related to geographical difference in the South China Sea.