Ni Xuejiao, Qi Xing'e, Gu Yanling, Zheng Xiaoji, Dong Juan, Ni Yongqing, Cheng Guodong
Wei Sheng Wu Xue Bao. 2014 Nov 4;54(11):1256-66.
The purpose of this study is to characterize the community composition and phylogenetic analysis of cyanobacteria from supraglacial cryoconite of the Glacier No. 1 in the Tianshan Mountains, China.
We amplified 16S rRNA genes from the extracted cryoconite DNA by PCR with 2 pairs of cyanobacteria-specific primers. Amplificon was used to construct 16S rRNA genes clone library. The estimation of species richness, diversity indices, and rarefaction curve of the 16S rRNA genes library were determined based on representative phylotypes (OTUs).
Analysis of 16S rRNA gene sequences allowed grouping of 101 clones into 12 phylotypes (OTUs) using a cut-off of 97% identity. The phylogenetic analysis revealed that most of sequences affiliated to the order Oscillatoriales and Chroococcales except that three were unclassified. The clone library was dominated by representatives of the order Oscillatoriales (81% of the total clones), and the most abundant organisms within this order were in the genus Phormidium (68 clones) including clones grouping into four phylotypes. The only clone of Chroococcales was closely related to the genus Chamaesiphon with 97% similarity. In addition, comparison of soil chemical properties between different habitats indicated that supraglacial cryoconite supported significantly higher the content of available phosphorus and potassium, nitrate nitrogen and organic matter compared with the forefield of the Glacier No. 1.
The diversity index of cyanobacteria were relatively high in supraglacial cryoconite of the Glacier No. 1 in the Tianshan Mountains. The community structure was dominated by members of the genus Phormidium. This study may enrich our knowledge on biogeochemical processes and ecological distribution of cyanobacterial populations in glacial ecosystem.
本研究旨在对中国天山一号冰川表碛冰尘中的蓝藻进行群落组成特征分析及系统发育分析。
我们用2对蓝藻特异性引物通过聚合酶链式反应（PCR）从提取的冰尘DNA中扩增16S rRNA基因。扩增产物用于构建16S rRNA基因克隆文库。基于代表性系统发育型（操作分类单元，OTUs）确定16S rRNA基因文库的物种丰富度估计值、多样性指数和稀疏曲线。
16S rRNA基因序列分析允许使用97%的同一性阈值将101个克隆分为12个系统发育型（OTUs）。系统发育分析表明，除了3个未分类的序列外，大多数序列隶属于颤藻目和色球藻目。克隆文库以颤藻目代表为主（占总克隆数的81%），该目中最丰富的生物是席藻属（68个克隆），包括分为4个系统发育型的克隆。色球藻目的唯一克隆与裂须藻属密切相关，相似度为97%。此外，不同生境土壤化学性质的比较表明，与一号冰川前缘相比，表碛冰尘中有效磷、钾、硝态氮和有机质的含量显著更高。
天山一号冰川表碛冰尘中蓝藻的多样性指数相对较高。群落结构以席藻属成员为主。本研究可能丰富我们对冰川生态系统中蓝藻种群生物地球化学过程和生态分布的认识。
