基于pufM基因的乌梁素海富营养化湖区好氧不产氧光合细菌系统发育多样性分析

Phylogenetic Diversity of Aerobic Anoxygenic Phototrophic Bacteria in Eutrophic Zone of Lake Ulansuhai Based on Gene pufM

摘要:

好氧不产氧光合细菌(AAPB)的多样性在海洋中已经广泛研究, 但在富营养化湖泊中却研究甚少。通过构建和分析AAPB光合中心合成中的关键基因pufM克隆文库, 以期揭示乌梁素海富营养化湖区AAPB分布及其系统发育多样性, 探讨其在富营养化湖泊中的功能和作用。对乌梁素海红圪卜湖区水体文库中的52个克隆子进行分析, 产生了28个OTU, 文库覆盖度达到71.4%, 反映出文库有较好的代表性。同源性和系统发育分析结果表明, 乌梁素海红圪卜湖区AAPB有较高的多样性, 与我们之前所发现的同一湖区总细菌多样性较低形成鲜明对比。所获得的序列分属7个亚群, 即γ-Proteobacteria (44.2%, 含Group-1, -2和-3共3个亚群)、β-Proteobacteria (21.2%)、Rhodobacter-like (7.69%)及2个未知亚群unknown Group-1 (21.2%)和Group-2 (5.77%)。其中γ-Proteobacteria占到总克隆的44.2%, 在低盐的乌梁素海环境中出现高比例的γ-Proteobacteria之前并未见类似报道, 并且乌梁素海中存在一些可能是富营养化湖泊特有的AAPB。这表明AAPB可能在富营养化湖泊生态系统的维持和稳定中有重要作用。

Abstract:

The diversity of aerobic anoxygenic phototrophic bacteria (AAPB) has been well examined in marine habitats, but that in eutrophic lake are little known. Gene pufM is related to biosynthesis of photosynthetic reaction center and is widely used in diversity analysis of AAPB. This study constructed and analyzed pufM gene library, to reveal the distribution and phylogenetic diversity of AAPB and discuss their role of AAPB in eutrophic zone of Lake Ulansuhai. 52 clones of the library were obtained, analyzed and clustered into 28 operational taxonomic units (OTUs). Coverage analysis showed that the library coverage value was of 71.4%, which indicated that the clone library could provide a fine inventory of AAPB diversity in the lake. Phylogenetic and statistical analysis of clone library revealed a higher AAPB diversity in the lake, which has a sharp contrast with lower total bacteria diversity of the same lake according to our previous study. Sequences obtained in this study belonged to seven subgroups, namely γ-Proteobacteria (44.2%, including Group-1, -2 and -3), β-Proteobacteria (21.2%), Rhodobacter-like (7.69%) and unknown Group-1 (21.2%) and Group-2 (5.77%). Higher proportion of γ-Proteobacteria in lower salinity lake like Ulansuhai, has not been reported before. Some unique AAPB ecotypes were probably related to eutrophic lake habitat. This suggested that AAPB play an important role in maintenance and stability of eutrophic lake ecosystems.