The Diversity And Abundance Of Archaea In The Sediments Of Northern Continental Slope Of South China Sea

South China Sea belongs to western Pacific,and it is the third largest marginal sea in the world,it contains large amount of resources,such as petroleum and gas hydrate,playing a very important role in economy and politcs.The research of archaea diversity and abundance in sediment at northern continental slope of South China Sea is the basis to understand archaeal microbial global biogeochemical cycles.Archaea are recognized as key players participating in the global biogeochemical cycles in marine sediment.Archaeal diversity in the sediments of three areas at the northern continental slope of SCS was surveyed using high-through sequencing for 16S ribosomal RNA gene.The major archaeal groups in the sediments include Bathyarchaeota,Thermoplasmata,Woesearchaeota(DHVEG-6),Thaumarchaeota(Marine Group I),Lokiarchaeota and Marine Hydrothermal Vent Group(MHVG),also with low abundance of AK8,Marine Benthic Group A and Terrestrial Hot Spring Crenarchaeota Group(THSCG).Anaerobic methane oxidation(AOM)microbes,mainly ANME-1,ANME-2ab and ANME-2c were also found in the potential gas(methane)hydrate zone.Methyl coenzyme-M reductase alpha subunit(mcrA)gene,which encodes the key enzyme in methane metabolism,was also recovered from these sites,implying potentially active archaea mediated methane cycling.Quantitative PCR results showed that the abundance of bacterial 16S rRNA gene,archaeal 16S rRNA gene and mcrA gene were 10~5-10~7 copies/g(wet weight),10~5-10~6copies/g(wet weight)and 10~3-10~5 copies/g(wet weight),respectively.All together,these results revealed high diversity of archaea and rich microbial recourses in SCS sediments,layed the foundation for further analysis and understanding of archaea mediated carbon cycling in the sediments of SCS.