Bacterial diversity in the meltwater at -183 m depth of the Dalk Glacier in eastern Antarctica

Abstract:

[Objective] Currently, there are few studies on microorganisms in Antarctic ice cores, and the available studies mostly employ the pure culture and high-throughput sequencing methods, with limited knowledge about the microbial diversity. We studied the microbial community composition of the meltwater at -183 m depth of the Dalk Glacier in eastern Antarctica, aiming to provide a reference for the development of extremophiles in Antarctica. [Methods] we employed the culture, single-cell sorting, and high-throughput sequencing methods to study the microbial community composition in the meltwater at -183 m depth of the Dalk Glacier. [Results] We obtained bacterial isolates belonging to 94 genera, 19 orders of 10 phyla, in which Proteobacteria, Alphaproteobacteria, and Sphingomonas were the dominant phylum, order, and genus, respectively. This result indicated high microbial diversity in the meltwater. The culture, single-cell sorting, and high-throughput sequencing yielded 25 bacterial strains, 24 bacterial strains, and 55 183 sequences (116 operational taxonomic units), respectively. The dominant taxa were different among the three methods. By the culture and single-cell sorting methods, we identified 7 bacterial strains with the 16S rRNA gene identity less than 98.65% compared with their closest relatives in GenBank, of which two strains had the identity less than 95.00% identity. Accordingly, we inferred that there may be two potential new genera and five potential new species. [Conclusion] We studied the microbial diversity in the meltwater of the Dalk Glacier in eastern Antarctica by using the culture, single-cell sorting, and high-throughput sequencing method and discovered rich bacterial species in the meltwater. Each method has its own advantages and limitations. This means that when studying microbial diversity, more comprehensive information about the composition of the microbial community can be obtained by combining different methods. The results of this study can serve as a reference for further research on the genetic resources in Antarctica.