[Microbial diversity in sediments of core HS-PC 500 from Shenhu Area, northern South China Sea]
Jiao L, Su X, Chen F, Zhang Y, Jiang H, Luo Y, Dong H
Geomicrobiology Laboratory, Beijing 100083, China.
We studied the microbial diversity in the sediments of different depth in a gravity piston core HS-PC500 from Shenhu Area, the northern of South China Sea.
Total DNA was extracted from the sedimental materials; the archaeal and bacterial 16S rRNA gene sequences were amplified. The clone libraries were used to analyze the microbial systematic development.
Group C3 was the predominant archaeal group in the top layer (0-5 cm bsf) sediments, and the Marine Benthic Group (MBG)-B group became predominant with depth, reaching 38.9% and 62.5% in the middle (350-355 cm bsf) and bottom (790-795 cm bsf) sediments. Some belonged to MBG-A, Miscellaneous Crenarchaeotic Group (MCG), Thermoprotei, Novel Group Crenarchaeota (NGC), Halobacteriales, MBG-E, South African Gold Mine Euryarchaeotic Group (SAGMEG). Proteobacteria was the dominant bacterial group in the top of the core, but became minor deeper within the sediments. As depth increased, Chloroflexi and candidate division JS1 became the predominant groups and reached up to 28.1%, 29.2% and 39%, 24.7%. Other sequences respectively belonged to Nitrospirae, Actinobacteria, Acidobacteria, candidate division OP8, Spirochaetes, candidate division TM6, Deferribacteres and Plantomycete.
Down-core variation in microbial abundance in sediments of HS-PC500 was consistent with the changes of methane concentration in the same core; the lower microbial abundance might be probably due to lower total organic carbon (TOC) in sediments; However, microbial diversity was relatively high and community structure varied apparently with depth; the community was dominated by clusters that was dominated in sulfate reduction condition, suggesting that microbial metabolization played very important role in the material cycle of marine sediments.