长江流域好氧不产氧光合异养细菌的空间分布及其影响因素

Spatial Distribution and Environmental Factors that Influence Aerobic Anoxygenic Photosynthetic Bacteria in the Yangtze River Basin

为探讨长江流域水体微生物和光合异养细菌基因丰度的空间分布特征及其对环境因子的响应机制,于2016年10月沿长江流域干流和主要一级支流进行了采样调查。利用分子生物学技术,分析长江流域干流和主要一级支流水体微生物16S rRNA基因和好氧不产氧光合异养细菌(Aerobic Anoxygenic Phototrophic Bacteria,AAPB)puf M基因丰度的空间分布特征,并探讨了其环境驱动机制。结果表明,流域内16S rRNA基因丰度为0.02×10^(6)~811.78×10^(6)copies/L,变幅高达40 589倍;puf M基因在各样品中均有分布,丰度为0.62×10^(2)~250.86×10^(2)copies/L,变幅高达405倍,16S rRNA基因和puf M基因丰度均无明显的空间变化规律。研究区16S rRNA和puf M基因丰度与水体浮游植物及浮游藻类活动负相关,表现出明显的竞争关系,岩溶水库坝前采样点的AAPB相对丰度明显高于其他采样点。相比地表河,岩溶水库环境更有利于AAPB生存,其平缓流速有利于AAPB形成集群或聚合物沉降,岩溶水库沉积较多的有机质为AAPB提供了充足的有机质底物。研究结果可为后续长江流域内碳循环相关的生态作用研究提供参考。

This study explored the spatial distribution of micro-organisms and the abundance of aerobic anoxygenic phototrophic bacteria(AAPB)in the mainstream and primary tributaries of the Yangtze River basin as well as their response to environmental factors.In October 2016,water and micro-organism samples were collected at 14 sampling sites in the mainstream and primary tributaries of Yangtze River and water quality parameters at each sampling site were monitored simultaneously.Molecular biological techniques were used in this study to determine the abundance of the micro-organism 16S r RNA gene and AAPB puf M gene.The abundance of the 16S rRNA gene ranged from 0.02×10^(6)copies/L to811.78×10^(6)copies/L(a variation of factor 40589).The puf M gene ranged from 0.62×10^(2) copies/L to250.86×10^(2) copies/L(factor 405).Neither gene displayed obvious rules of spatial variation.The 16S r RNA and the puf M genes competed with the phytoplankton and algal communities,based on the negative correlation of gene abundance with environmental factors indicating phytoplankton and algal activity.However,the relative abundance of AAPB at the sampling site above the karst reservoir dam was significantly higher than that at other sampling sites,indicating that the karst environment is more conducive to AAPB survival than typical rivers.The low flow velocity is conducive to AAPB cluster formation and settling,and the organic matter deposited in the reservoir provides sufficient substrate for AAPB growth.The results of this study fill the research gap on AAPB distribution in the Yangtze River basin and provide a basis for subsequent research on the role of AAPB in carbon cycling in the river basin.