Archaeal diversity in deep-sea hydrothermal sediments from the East Pacific Rise

Archaeal diversity of deep-sea hydrothermal sediments from 3 sites on the East Pacific Rise was investigated and analyzed with polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP).Phylogenetic analyses revealed that a total of 296 random 16 S rRNA gene clones were assigned to Thaumarchaeota(47.64%),Euryarchaeota(44.93%),Crenarchaeota(6.77%) and unclassified Archaea(0.68%).Among them,the genus Nitrosopumilus belonging to the phylum Thaumarchaeota and the class Thermoplasmata belonging to the phylum Euryarchaeota were the dominant groups,representing 35.47% and 27.03% of archaeal clones,respectively.In addition,some archaeal 16 S rRNA gene sequences were affiliated with deep-sea hydrothermal vent Euryarchaeota 3,5 and 6(DHVE3,DHVE5 and DHVE6),and Marine Benthic Group B and G(MBGB and MBGE).Archaeal communities in sediments from 3 sites on East Pacific Rise were clearly distinct from each other.97 archaeal clones from S5-TVG1 site were divided to Thaumarchaeota(49.48%),Euryarchaeota(49.48%) and Crenarchaeota(1.03%).103 archaeal clones from S14-TVG10 site belonged to Thaumarchaeota(84.47%) and Euryarchaeota(15.53%).96 archaeal clones from S16-TVG12 site were assigned to Euryarchaeota(71.88%),Crenarchaeota(19.79%),Thaumarchaeota(6.25%) and unclassified Archaea(2.08%).Our results indicate that Archaea is abundant and there are a lot of novel archaeal groups in deep-sea hydrothermal sediments from 3sites on the East Pacific Rise,and the distinct community structure and diversity of Archaea in deep-sea hydrother-mal sediments suggested that the sampling area was influenced by hydrothermalism.