东南极达尔克冰川-183m深处冰层融水细菌多样性研究

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

摘要:

【目的】目前对于南极冰层微生物研究较少，而且研究手段多为纯培养和高通量测序，对于其中的微生物群落多样性仍知之甚少。本研究拟研究东南极达尔克冰川冰层中微生物群落组成。【方法】采用纯培养法、单细胞分选和高通量测序3种方法对东南极达尔克冰川冰层微生物进行研究，探究该生境中微生物的群落组成。【结果】从达尔克冰川中分离出10门19纲94属。其中，变形菌门(Proteobacteria)为优势菌门，α-变形菌纲(Alphaproteobacteria)为优势纲，鞘氨醇单胞菌属(Sphingomonas)为优势属，结果显示冰层中存在较为丰富的微生物多样性。其中，纯培养法分离出25株细菌。单细胞分选方法分离得到24株细菌。高通量测序共得到55 183条序列，聚类出116个操作分类单元(operational taxonomic unit, OTU)。3种研究方法得出的优势种群不尽相同。通过单细胞分选和纯培养法共获得7株细菌，它们与数据库最近源16S rRNA基因序列的相似度小于98.65%，其中有2株菌株与最近源16S rRNA基因序列的相似度小于95.00%，推测可能有2个潜在新属，5个潜在新种。【结论】本研究通过纯培养法、单细胞分选以及高通量测序3种方法对东南极达尔克冰川冰层微生物多样性进行研究发现，该生境中细菌多样性复杂。对比3种方法，其各有优势和局限性。这意味着结合使用多种研究方法研究微生物多样性，可获得更加全面的微生物群落组成。研究结果可为挖掘南极微生物资源提供数据基础。

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.