南极普利兹湾夏季海冰不同层次细菌丰度及多样性

Bacterial diversity within different sections of summer sea-ice samples from the Prydz Bay,Antarctica

【目的】为了解南极普利兹湾夏季海冰不同层次中细菌群落丰度及组成。【方法】利用荧光原位杂交技术对海冰不同层次中细菌进行定量研究,通过构建16S rRNA基因文库对海冰不同层次中细菌进行多样性分析,并结合环境因子进行相关性分析。【结果】荧光原位杂交结果表明,细菌占海冰总细胞数比例随着海冰层次下降呈现上升趋势,初步推断可能受海冰中总有机碳,总有机氮以及磷酸盐影响所致。16SrRNA基因文库分析结果表明,上、中、底3个海冰分层样品获得的16 S rRNA基因序列归属于γ-变形细菌纲(γ-Proteobacteria),α-变形细菌纲(α-Proteobacteria)以及拟杆菌门(Bacteroidetes),多数16S rRNA基因序列与分离培养自海洋环境、南北极海冰菌株的16S rRNA基因序列相似性较高(90%-99%);在海冰底部样品中未检测到拟杆菌门;海冰不同层次中,细菌组成呈现些微的差异性,可能由铵离子在海冰不同层次的分布造成。【结论】海冰底部细菌数量最丰富。在海冰中,γ-变形细菌纲为优势类群。

[Objective] In order to assess bacterial abundance and diversity within three different sections of summer sea-ice samples collected from the Prydz Bay,Antarctica.[Methods] Fluorescence in situ hybridization was applied to determine the proportions of Bacteria in sea-ice.Bacterial community composition within sea ice was analyzed by 16S rRNA gene clone library construction.Correlation analysis was performed between the physicochemical parameters and the bacterial diversity and abundance within sea ice.[Results] The result of fluorescence in situ hybridization shows that bacteria were abundant in the bottom section,and the concentration of total organic carbon,total organic nitrogen and phosphate may be the main factors for bacterial abundance.In bacterial 16S rRNA gene libraries of sea-ice,nearly complete 16S rRNA gene sequences were grouped into three distinct lineages of Bacteria（γ-Proteobacteria,α-Proteobacteria and Bacteroidetes）.Most clone sequences were related to cultured bacterial isolates from the marine environment,arctic and Antarctic sea-ice with high similarity.The member of Bacteroidetes was not detected in the bottom section of sea-ice.The bacterial communities within sea-ice were little heterogeneous at the genus-level between different sections,and the concentration of NH4＋ may cause this distribution.[Conclusion] The number of bacteria was abundant in the bottom section of sea-ice.Gamma-proteobacteria was the dominant bacterial lineage in sea-ice.