Composition of bacterial communities in deep-sea sediments from the South China Sea, the Andaman Sea and the Indian Ocean

Abstract

The bacterial diversity of deep-sea sediments collected from the South China Sea (B111), the Andaman Sea (ADM), and the Indian Ocean (P10) was investigated through the construction of 16S recombinant deoxyribonucleic acid (DNA) clone libraries for sequencing. The structure of the bacterial community and their phylogenetic relationships were analyzed using the Mothur software. The nutrient and heavy metal content of the sediments were also analyzed. In total, 263 valid sequences were obtained from 300 sequenced clones. There were 151 operational taxonomic units (OTUs) that belong to Actinobacteria, Proteobacteria, Planctomycetes, Bacteroidetes, Gemmatimonadetes, Nitrospira, Chloroflexi, Acidobacteria, WS3, BRC1, OD1, and numerous unclassified bacteria. The Chao1 and Shannon indices showed that B111 had the highest diversity, but P10 had the richest OTUs. The P < 0.05 value of the parsimony index, LIBSHUFF, and weighted UniFrac analyses indicated important distinctions in the structure and diversity of the bacterial communities. These differences are related to the nutrient and heavy metal content of the sediments. The present study clearly demonstrates the wide bacterial diversity in deep-sea sediments from the South China Sea, the ADM, and the P10, including a large number of unknown bacteria. Due to the different geographical locations of the sediments, the structures of their bacterial communities are also remarkably distinct. Key words: Deep-sea sediments, bacterial diversity, bacterial community structure.