2011年夏季北极王湾细菌群落结构分析及浮游细菌丰度检测

BACTERIAL COMMUNITY COMPOSITION AND ABUNDANCE OF PLANKTONIC BACTERIA IN ARCTIC KONGSFJORDEN IN THE SUMMER OF 2011

采用PCR-DGGE方法,对2011年夏季北极王湾表层海水及沉积物细菌的群落分析结果表明,沉积物中的细菌多样性指数高于海水。深水站位(S1和S3)的沉积物细菌群落不但与浮游细菌群落存在差异,并且与浅水站位(S5)也存在差异。位于湾口、湾内的浮游细菌群落组成也存在一定差异。测序结果显示,王湾海洋细菌的多样性组成包括α-变形细菌、γ-变形细菌、δ-变形细菌、放线菌、拟杆菌及厚壁菌等类群。基于定量PCR方法的检测结果表明,位于湾口、湾内的浮游细菌丰度相似,但湾内玫瑰杆菌支系的丰度明显低于湾口。研究结果表明,与湾口相比,王湾湾内的细菌群落受陆源性淡水输入的影响明显,不但表现在细菌群落的多样性组成上,也表现在某些特定细菌类群的数量分布上。

Bacteria are one of major components of the marine food web and play an important role in marine ecosystems. High abundance of bacteria has been reported in Kongsfjorden, a typical Arctic fjord on the northwestern coast of Svalbard. Freshwater input from glaciers inevitably affects the bacterial communities in Kongsfjorden during the summer season. Community fingerprint analysis of surface water and sediment samples collected in the summer of 2011 was performed using a polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE） approach. Sediment bacterial communities showed a higher diversity index than communities in surface seawater. Because of the influence of terrestrial freshwater input, communities in sediments from stations deeper than 200 m differed from communities in surface seawaters and communities in sediments from stations shallower than 40 m. Differences in planktonic bacterial community compositions were also observed between the inner and outer part of the fjord. Sequences of DGGE bands fell into six major lineages of the domain Bacteria, including or, ~/, and Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. In contrast to a similar abundance of planktonic bacteria between the outer and inner part of Kongsfjorden on quantitative PCR （QPCR） assay, there was a higher abundance of the Roseobacter Clade in the outer part compared with the inner part of the fjord. Results suggest that compared with the outer part, the inner part of Kongsfjorden is more affected by terrestrial freshwater input, resulting in differences in bacterial community composition as well as in abundance of specific bacterial species. In addition, comparison with a similar investigation in the summer of 2007 showed lower diversity of planktonic bacteria in 2011. Whether this finding reflects the response of bacterial communities in Kongsfjorden to global climate change remains uncertain.