摘要： 为进一步了解和认识APB及其在盐碱湖中的生态功能及其作用机制,通过构建和分析不产氧光合细菌bchY基因克隆文库,揭示其中不产氧光合细菌的多样性、群落结构及其与生存环境的关系。样品采自内蒙古浑善达克沙地盐碱度较高的扎格斯台和达格淖2个湖的水样,提取了样品总DNA。以bchY作为检测APB的通用标记,用PCR扩增方法构建了其bchY文库,并对扩增产物进行了测序与系统发育分析。结果表明,达格淖湖和扎各斯台湖均为富营养化盐碱湖,且两湖盐度相差很大。利用bchY文库中核酸序列对应的氨基酸序列进行分析,两文库覆盖度均达93.0%以上,代表性较强,共得到108条bchY编码的氨基酸序列,以cutoff=0.03和0.12分别在种和属水平进行同源性和系统发育分析,在cutoff=0.03分为17个OTUs。两湖的多样性指数(Shannon-Weaver和Simpson)和均匀度指数(Evenness)较接近,其种群多样性程度和均匀程度比较相似,但二者的Chao1都不太高,说明两湖APB的多样性较低,种群不丰富。达格淖湖的Margalef指数较高,说明前者物种数目比后者多。两湖的不产氧光合细菌均属Alphaproteobacteria纲,最优势菌群均为Roseibacterium elongatum。同源性及系统发育性分析表明,达格淖湖和扎各斯台湖中不产氧光合细菌的主要类型为AAPB-like类群、多样性低。

关键词: 盐碱湖, 不产氧光合细菌(APB), bchY基因, cutoff值, OTUs, 系统发育分析, 多样性, 基因克隆文库

Abstract: Reports about research on the diversity of Anoxygenic phototrophic bacteria(APB)in haloalkaline lakes are too rarely.This experiment constructed and analyzed Anoxygenic phototrophic bacteria bchY gene library of Dagenao Lake and Zagesitai Lake to reveal the diversity and community structure of APB in two lakes and their relation with living environment for the sake of understanding APB and their ecology function and its mechanism.The water samples were collected from the Dagenao Lake and Zagesitai Lake which have higher salinity in Hunshandake desert in Inner Mongolia,and their total DNA were extracted.Their bchY libraries were constructed by PCR amplification method using bchY as standard marker for the detection of APB,the amplification products were sequenced and the phylogenetic analysis has been carried out.The results showed that Dagenao Lake and Zagesitai Lake were Eutrophical haloalkaline lakes and the salinity of two lakes was obviously different.Analysis of the amino acid sequences encoded by bchY nucleotide sequences in two libraries discovered that the coverages of two lakes were over 93% and strongly representative.108 amino acid sequences encoded by bchY were obtained from the two libraries totally and these sequences were divided into 17 operational taxonomic units(OTUs)with the cutoff value of 0.03 and analyzed the similarity and phylotype composition under the genus(0.12)and species(0.03)lever.The diversity index and evenness index of two lakes were too approaching,therefore the diversity and evenness of species in two lakes were very similar,while their Chao1 values were law,indicated that the diversities of APB in two lakes were relatively low and the species were not too abundant.The Margalef index of Dagenao Lake was more higher,which indicated that the number of species in Dagenao Lake was more than Zagesitai Lake.In both libraries all of APB belonged to Alphaproteo bacteria class,and the predominant OTUs was Roseibacterium elongatum, diversity of APB in two lakes were similar and lower.Analysis of the similarity and phylotype composition revealed that the main type of APB was AAPB-like group,and the diversity of APB was lower.This study provided theoretical foundation and basis for understanding APB and their ecological role and function.

Key words: Haloalkaline lake, Anoxygenic phototrophic bacteria(APB), bchY gene, Cutoff value, OTUs, Analysis of phylotype composition, Diversity, Gene library

中图分类号: 

• Q938.1