本文通过构建克隆文库和基因测序的方法研究了西南印度洋真光层海水中固氮细菌nifH基因的多样性。从构建的2个nifH基因克隆文库中共获得76条有效序列,其中46条来自CTD13-30 m文库,分属10个OTUs;30条来自CTD13-125 m文库,分属8个OTUs。系统发育分析结果显示,研究站位nifH基因序列主要分布于Cluster I和Cluster III两个分支,其中Cluster I中包含蓝细菌和变形菌两个分支,蓝细菌以Group B为优势类群,并未获得束毛藻和Group A的nifH基因序列。此外还有少数nifH基因序列分布于Cluster II。总体来看,西南印度洋固氮生物基因与大西洋的亲缘关系更近;固氮生物的多样性较为丰富,受环境条件的影响,群落结构与其它热带、亚热带寡营养海域具有明显的不同。
Abstract
Our knowledge on diazotrophs is limited in the Indian Ocean, which is considered an important source of biological N2 fixation of the global ocean. Phylogenetic diversity of nifH genes in the southwest Indian Ocean was studied through cloning and sequencing methods. After sequences were checked, two nifH gene libraries were established. Overall, 76 nifH gene sequences are recovered from Station CTD13, including 46 nifH gene sequences of 10 OTUs from libraries CTD13-30 m, and 30 nifH gene sequences of 8 OTUs from libraries CTD13-125 m, respectively. Results of phylogenetic analysis show that most nifH gene sequences fall into Cluster I and III, only 3 recovered nifH gene sequences are grouped with Cluster II. In Cluster I, most of nifH gene sequences cluster with unicellular cyanobacteria Group B, while in Cluster III, most nifH gene sequences are closely related with uncultured clone from active sludge. No nifH gene sequences clustered with Trichodesmium are recovered, which may be attributed to low water temperature. In general, diazotroph community in the southwest Indian Ocean is different from those in tropical and subtropical oligotrophic ocean.
关键词
固氮生物 /
nifH基因 /
多样性 /
西南印度洋
Key words
diazotroph /
nifH gene /
diversity /
the southwest Indian Ocean
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基金
国家自然科学基金项目资助(41206104); 国际海域资源调查与开发“十二五”课题资助(DY125-11-E-03)
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