天山乌鲁木齐河源一号冰川表面粉尘蓝细菌群落结构及其系统发育

Community structure and phylogenetic analysis of cyanobacteria in cryoconite from surface of the Glacier No.1 in the Tianshan Mountains

摘要:

摘要:【目的】揭示天山乌鲁木齐河源一号冰川表面粉尘中蓝细菌多样性、群落结构及其系统发育，为科学评价冰川表面及相关环境中功能微生物的地球化学循环作用提供参考依据。【方法】采用两对蓝细菌16Sr RNA基因特异引物扩增并构建克隆文库，基于序列相似性归类OTU并统计多样性，代表OTU序列与NCBI、RDP数据库比对后构建系统发育树。【结果】天山一号冰川表面粉尘101个蓝细菌克隆序列基于97%的相似性被划分为12个OTU，shannon多样性指数为1.522，系统发育分析显示主要隶属于颤蓝细菌目 (Oscillatoriales)和色球蓝细菌目(Chroococcales)。Oscillatoriales包括席蓝细菌属(Phormidium)、微鞘蓝细菌属(Microcoleus)、伪鱼腥蓝细菌属(Pseudanabaena)和颤蓝细菌属(Oscillatoria)4个属，其中Phormidium占绝对优势，68个克隆序列划分为4个OTU，其它3个属的序列较少。Chroococcales仅有1个克隆，与亚球形管胞蓝细菌(Chamaesiphon subglobosus)亲缘关系很近。此外，发现一号冰川表面粉尘的速效磷、速效钾含量是冰川退缩前沿50 m－500 m距离土壤的2－5倍，硝态氮达到10－20倍，有机质含量达到3－9倍，显著高于冰川前沿环境。【结论】天山一号冰川表面粉尘蓝细菌的多样性指数相对较高，以隶属于Phormidium属的成员占绝对优势，对其生态学作用需进一步深入探究。

Abstract:

Abstract:［Objective］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．［Methods］ 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). ［Results］ 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.［Conclusion］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．