南极普里兹湾可培养浮游细菌群落结构研究

针对南极普里兹湾内达恩利角附近海域的3个测站共12份海水样品,采用寡营养培养基分离培养极地浮游细菌,通过PCR方法获取其中95株细菌的16S rRNA基因序列。序列分析结果表明,分离获得的95株细菌分属α-变形杆菌纲(Alphaproteobactia)、γ-变形杆菌纲(Gammaproteobacteria)和拟杆菌门(Bacteroidetes)3个类群下的35个不同分类单元,其中α-变形杆菌纲为优势细菌,在不同水层中所占的比例为52.6%—62.5%。通过Shannon多样性指数分析发现,南极普里兹湾陆架区测站P2-14多样性指数较陆坡区两测站P2-11和P2-8的高,细菌多样性与浮游植物量和生产力水平呈现正相关。表层细菌Shannon多样性指数最低,50 m水层最高,100和200 m水层多样性指数变化不明显,真光层水体中细菌垂直分布与营养盐和溶解氧浓度存在关联。此外,采用寡营养陈海水培养基,还获得了一些与已报道的16S rRNA基因序列相似性较低的菌株,它们代表了微生物新物种,可能也是南极真光层特有的细菌。研究工作表明,南极普里兹湾真光层水体中蕴藏着丰富的浮游细菌资源,它们有待保护、开发和利用。

COMMUNITY COMPOSITION OF ANTARCTIC BACTERIOPLANKTON ISOLATED FROM THE PRYDZ BAY,ANTARCTICA

Twelve sea water samples of three stations from the Antarctic Prydz Bay, near Cape Darnley, were collected. Based on the oligographic media, totally 95 strains of antarctic bacterioplankton were isolated. The 16S rRNA gene sequences were determined and analyzed. The isolates fell into three lineages: Alphaproteobactia, Gammaproteobacteria and Bacteroidetes. The sequences were assigned to 35 operational taxonomic units (OTUs) based on sequence analysis. The results revealed that the Alphaproteobactia was the dominant bacterial groups and the proportions were 52.6~62.5% in different layers. Analysis using shannon diversity index indicated that station P2-14 located in continental shelf was higher than station P2-11 and P2-8 located in Slope area. There was a positive correlation between the bacteria diversity and biomass as well as productivity of phytoplankton. Shannon diversity index of the surface is the lowest, and Shannon diversity index of 50 m layer is highest. There was no difference of Shannon diversity index between 100 and 200 m layers. Bacteria vertical distribution is correlated to the nutrient concentration and dissolved Oxygen. In addition, some strains isolated from oligographic media showed low affiliation with the sequences from the described species (less than 97 %), suggesting the presence of some novel taxa and the specific strains in antarctic euphotic layer. Therefore as it is revealed in this study, the bacterioplankton resources are rich in antarctic euphotic layer. Massive unknown microorganism deserve further studying and exploration as valuable resources．