Actinobacterial diversity in the deep-sea sediments of the South China Sea

Abstract:

[Objective] The purpose of the study was to analyze the actinobacterial diversity in the deep-sea sediments of the South China Sea by using culture-independent and culture-dependent approach. [Methods] Actinobacteria-specific 16S rRNA gene clone library was constructed. Representative clones selected based on the restriction fragment length polymorphism analysis were sequenced and placed into operational taxonomic unit (OTU) groups according to the 16S rRNA gene sequence similarity. Diversity statistics were analyzed using SPADE analysis software. Eight media were used to isolate actinobacteria strains from 11 sediment samples. 16S rRNA gene sequences of the representatives were sequenced to analyze phylogenetic diversity of the actinobacteria. [Results] Forty and ninety-nine positive clones were obtained from the two libraries and placed into 16 and 34 OTUs respectively. Both two libraries contained class Actinobacteria, Acidimicrobiia, Nitriliruptoria and Thermoleophilia. The dominant population of site N40-4 and N63-4 were order Streptomycetales and Nitriliruptorales respectively. Forty-one strains were obtained by the culture-dependent approach. Analysis of the 16S rRNA gene sequences of 19 representative strains showed that these strains belong to 10 different genera and 12 different species. [Conclusion] The deep-sea sediments of the South China Sea harbor abundant and diverse actinobacteria. The result also implied that there may be large numbers of unknown actinobacterial groups.