西藏纳木错沿岸表层水体浮游细菌群落结构及生态功能预测

Structure of bacterioplanktonic community and ecological function prediction in coastal surface water of Nam Co lake, Tibet

浮游细菌群落对高原湖泊变化具有高度响应性,并且会影响高原湖泊生境的地球化学平衡。因此,了解高原湖泊中浮游细菌群落的分布特征,阐明其在高原湖泊生态系统中的生态功能具有重要科学意义。2021年5月对纳木错沿岸浮游细菌群落分布特征进行了调查研究,并采用16S rDNA高通量测序技术对样品进行分析,通过α-多样性指数分析浮游细菌群落的差异性,通过共现网络分析浮游细菌群落之间的相互作用,利用Pearson相关系数衡量理化因子与α-多样性指数的相关性,采用冗余分析(RDA)探讨水体理化因子对浮游细菌群落结构的影响,并基于PICRUSTt2对纳木错浮游细菌进行功能预测。结果表明:浮游细菌群落主要由变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)、蓝细菌门(Cyanobacteria)和厚壁菌门(Firmicutes)组成,其中变形菌门相对丰度最高,主要包括γ-变形菌纲(Gamma-proteobacteria)和α-变形菌纲(Alpha-proteobacteria);噬氢菌属(Hydrogenophaga)和嗜冷菌属(Algoriphagus)为相对优势菌属。α-多样性指数表明,纳木错浮游细菌群落比较丰富。共现网络节点间关系以正相关为主;总溶解固体量(TDS)和盐度(Sal)是影响纳木错浮游细菌群落结构的关键因子。功能预测结果显示,纳木错浮游细菌群落功能主要涉及代谢、遗传信息处理、环境信息处理等6类生物代谢通路,以及膜运输、氨基酸代谢、碳水化合物代谢等46个子功能。综上所述,纳木错浮游细菌群落结构在各样点间存在一定差异,浮游细菌在门级水平上类群间相互作用主要为协同作用,其群落结构是多个因子共同作用的结果。研究阐明了纳木错浮游细菌群落组成和功能及其与环境因子的相互联系,可为当地生态环境保护提供科学依据。

It is of great scientific significance to understand the distribution characteristics of the bacterioplankton in the plateau lakes and clarify its ecological function of the plateau lake ecosystem. In May 2021, we investigated bacterial community in Nam Co lake samples were analyzed by 16S rDNA high-throughput sequencing technology, and the difference of bacterial community was analyzed by α-diversity index. The interaction among bacterial communities was analyzed by co-occurrence network. The correlation between environmental factors and α-diversity index was measured by Pearson correlation coefficient. Redundancy analysis(RDA) was used to investigate the relationship between physicochemical factors and bacterial community structure. Function of bacterioplankton in Nam Co lake was predicted based on PICRUSTt2. The results showed that bacterial community was mainly composed of Proteobacteria, Bacteroidetes, Actinobacteria, Cyanobacteria and Firmicutes. The relative abundance of Proteobacteria was the highest, mainly including Gamma-proteobacteria and Alpha-proteobacteria. Hydrogenophaga and Algoriphagus are the relative dominant species. The α-diversity index showed that the bacterial community was rich in Nam Co lake. The correlation among nodes of Nam Co lake co-occurrence network is mainly positive. Total dissolved salts(TDS) and salinity(Sal) were the key factors affecting the bacterial community structure. Functions of bacterioplankton in Nam Co lake mainly involved 6 metabolic pathways, such as metabolism, genetic information processing and environmental information processing and 46sub-functions of membrane transport, amino acid metabolism, carbohydrate metabolism, etc. In conclusion, bacterial community structure in Nam Co lake was different among various sites. At the phylum level, the interaction among bacterial groups was mainly synergistic, and the bacterial community structure in Nam Co lake was the result of multiple factors. This study clarified the composition and function of bacterioplankton in Nam Co lake and its relationship with environmental factors, providing scientific reference for the protection of ecological environment of plateau lakes.