Archaeal and bacterial community structures in the anoxic sediment of Antarctic meromictic lake Nurume-Ike

Prokaryotic community structures in the anoxic sediment of the Antarctic meromictic Lake Nurume-Ike were revealed by sequence analysis of 16S rRNA gene clones. The archaeal clones obtained (205 total) consisted of only three phylotypes, and were dominantly affiliated with uncultured euryarchaeotes. Specifically, 93% of the clones were identified as marine benthic group-D archaeal phylotype. In contrast to the limited archaeal diversity, 53 phylotypes were detected within 312 bacterial clones. Major bacterial phylotypes were affiliated with α-Proteobacteria (20% of clones), d-Proteobacteria (9%), Planctmycetales (7%), and Cyanobacteria (7%). A small numbers of clones belonging to γ-Proteobacteria, Actinobacteria, Spirochaetes, Flavobacteria, and Verrucomicrobia were also found. A total of 53% of the bacterial clones, consisting of 13 phylotypes, could not be classified into any known group. These results indicated that the bacterial community of Lake Nurume-Ike sediment consisted of numerous phylogenetic groups and had a diversity comparable to the diversity of other Antarctic lakes communities previously reported. Interestingly, however, there were very few phylotypes shared between the communities of lakes Nurume-Ike and five other lakes located in the Vestfold Hills area. This is the first comprehensive study to analyze more than 500 16S rDNA clones for microbial community analysis of an Antarctic lake sediment sample, and the results significantly expand current views of bacterial diversity in Antarctic lakes.