纳木错湖水体固碳微生物数量、群落结构及其驱动因子

湖泊是微生物固碳的主要生态系统之一,但青藏高原湖泊水体固碳微生物群落的研究还罕见报道。以纳木错为例,采用定量PCR和克隆文库方法,研究湖水中cbbL ID基因丰度和固碳微生物群落组成,并分析其与环境参数的关系。结果显示:纳木错湖水中存在较高丰度的cbbL ID类型固碳微生物,从表层到底层呈增加趋势,T2点底层达到最高值(6.37×10~8拷贝L~(-1)湖水)。cbbL ID类型固碳微生物共分四个类群,即不等鞭毛类(Stramenopiles),定鞭藻纲(Haptophyceae),蓝藻(Cyanobacteria)和隐藻门(Cryptophyta)。其中占主要的是Stramenopiles和Haptophyceae。Stramenopiles类群的多样性较高(含7个纲,13个科),其他类群只有1个科。相关性分析表明Stramenopiles和Haptophyceae出现频率存在显著的负相关关系(P0.01)。湖水深度和pH与湖水cbbL ID基因丰度显著相关(P0.05,P0.01)。叶绿素含量与Stramenopiles和Haptophyceae出现频率显著相关(P0.01)。

Abundance, community structure, and the driving factors of Carbon fixing microorganisms in the Nam Co Lake

Lakes are one of the main ecosystems for carbon fixation; however, the microbial community for carbon fixation in the lakes of the Tibetan Plateau have rarely been reported. In this study, the Nam Co Lake was chosen to study the abundance of cbbL ID genes and their composition using quantitative PCR and a clone library method. We also discuss their relationship with environmental parameters. The results showed that there was a high abundance of the cbbL ID gene in the Nam Co Lake, and there was an increasing trend from the surface to the bottom, and the highest amount was in the bottom sample of T2 (6.37×10⁸ copies/L water). The community was mainly composed of Stramenopiles and Haptophyceae, and a few Cyanobacteria and Cryptophyta appeared on individual layers. The Stramenopiles group had a higher diversity (including 7 classes and 13 families) than that of the other groups, and there was only 1 family of another taxa. A correlation analysis showed there was a significant negative correlation (P<0.01) of the occurrence frequency of Stramenopiles and Haptophyceae. Water depth and pH had a significant correlation with cbbL ID gene abundance (P<0.05, P<0.01, respectively). Chlorophyll content had a significant correlation with the occurrence frequency of Stramenopiles and Haptophyceae.