Archaeal communities in the deep-sea sediments of the South China Sea revealed by Illumina high-throughput sequencing

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Archaea have important roles in global biogeochemical circulation. Although archaeal diversity and their ecological significance in deep-sea environments in the South China Sea (SCS) have been investigated, archaeal communities in deep-sea sediments below 2000 m water depth in the SCS are not well documented. The objective of our work was to investigate archaeal community structure in the four sediments (named as SCS2, SCS5, SCS8, and SCS10) collected from the SCS below 2000 m water depth. Illumina high-throughput sequencing was employed to reveal archaeal community structure. Archaeal communities were evaluated with QIIM software. Archaeal communities in the four sediments were dominated by Thaumarchaeota (55%), Bathyarchaeota (24%), Woesearchaeota (6%), Nanohaloarchaeota (4%), and Euryarchaeota (3%). Thaumarchaeota were abundant in the four samples. However, in SCS10, this phylum was almost exclusively represented. We revealed for the first time the presence of Nanohaloarchaeota in SCS2, SCS5, and SCS8. Comparative analysis showed that (1) the archaeal communities varied between the samples and (2) the samples varied between the samples. The detected archaea in each sample are known to be potentially participating in the carbon, nitrogen, and sulfur cycles, and methane metabolism. We present a comparative picture of archaeal communities, augmenting the current knowledge on archaeal diversity in deep-sea sediment environments in the SCS.