2010年夏季白令海浮游细菌的多样性和群落组成分析

摘要

海洋浮游细菌在海洋生态系统的运行中起着关键性的生物地球化学作用.利用2010年夏季第4次北极考察获得的白令海不同深度水样,运用变性梯度凝胶电泳技术以及克隆建库等方法,来了解白令海中浮游细菌的多样性和群落组成等信息.结果表明:在白令海海盆区B07站位的50 m处,其浮游细菌的香农多样性指数是最高的,为2.61;香农多样性指数最低的是B07站位的3 m处,为1.99.白令海海盆区的细菌多样性变化比陆架区要大,有可能与海洋环境的复杂变化有关.通过克隆测序,鉴定出的浮游细菌类群分为4大类:α-变形杆菌、β-变形杆菌、γ-变形杆菌和拟杆菌.其中γ-变形杆菌所占的比例最大,为53％,是白令海中的优势种群；拟杆菌其次,为37％.这些浮游细菌在白令海中的分布情况为:γ-变形杆菌和拟杆菌存在于3个位点的所有水层中,α-变形杆菌只存在于B07站位的50 m和100m水层中,β-变形杆菌除B13站位的0m处外,存在于其他站位的所有水层中.白令海B断面3个站位的温度随着深度的增加而降低,盐度随着深度的增加而升高.大体上白令海海盆区(B07站位)的硝酸盐、磷酸盐和硅酸盐浓度比陆架区(B15和B13站位)高,陆架区的铵盐浓度较海盆区高.%Marine bacterioplankton play a key biogeochemical role in the marine ecosystem.To investigate the diversity and community composition of bacterioplankton in the Bering Sea (Arctic Ocean),we collected samples from different depths during the Fourth Chinese National Arctic Research Expedition (2010 summer).Samples were analyzed using DGGE and clone libraries were constructed.In the basin area of the Bering Sea,the Shannon diversity index of bacterioplankton was highest (2.61) from B07-50 m,and lowest (1.99) from B07-3 m.There was greater variability in bacterial diversity within the basin than on the shelf of the Bering Sea,possibly related to complex changes in the marine environment.Through cloning and sequencing,the bacterioplankton was divided into four main phylogenetic groups:Alphaproteobacteria,Betaproteobacteria,Gammaproteobacteria and Bacteroidetes.Gammaproteobacteria dominated the samples,accounting for 53％ of all bacteria,with another 37％ identified as Bacteroides.The four groups varied in their spatial distribution,Gammaproteobacteria and Bacteroidetes were found at three sites(B07,B13 and B15),Alphaproteobacteria only existed in samples from 50 m and 100 m at B07,and Betaproteobacteria was found in all three sites,except for surface waters of B13.Temperature decreased and salinity increased with depth at the three stations in the B section of the Bering Sea.Generally,nitrate,phosphate and silicate concentrations were greater in the basin area (B07 station) than in the shelf area (B15 and B13 station).Conversely,ammonia concentration was greater in the shelf area than in the basin.