宁武亚高山湖泊细菌群落的时空格局及驱动机制

Spatio-temporal Patterns of Microbial Communities and Their Driving Mechanisms in Subalpine Lakes,Ningwu,Shanxi

受人类活动和气候变化的影响,亚高山湖泊生态系统日趋退化,导致微生物群落生物多样性和结构改变.本研究以宁武亚高山湖泊公海(GH)水体细菌群落为研究对象,通过Q-PCR和DGGE技术分析了不同季节和不同深度的水体中细菌群落多样性分布格局,探究细菌群落的时空动态及其多样性维持机制.结果表明,温度(T)、酸碱度(p H)、溶解氧(DO)、电导率(EC)、盐度(SAL)和铵态氮(NH4+)在每个月的不同采样深度间均有显著差异.细菌群落丰度具有明显的时空动态,其中8月的丰度最高,11月最低;在水体中层(2、4和6 m)的丰度较高,表层和底层(0 m和8 m)相对较低.细菌群落α多样性指数在各月份和不同深度间均有显著性差异,从4~12月整体上呈现先减少后增加的趋势.相似性分析(PERMANOVA)结果表明,不同深度之间细菌群落的空间分布格局明显不同(P<0.001).冗余分析(RDA)和方差分解(VPA)结果表明在不同深度下,细菌群落多样性格局是环境选择和扩散限制共同作用的结果,但是环境选择的相对作用更强,其中水体无机氮(NO3-、NO2-和NH4+)浓度是主要的影响因子.总之,宁武亚高山湖泊公海中细菌群落多样性有明显的时空分布格局,环境选择作为主要因素驱动了细菌群落的多样性格局.

Human activities and climate change cause the degradation of subalpine lake ecosystems,which induce the shift of microbial community structure. The spatio-temporal dynamics and the diversity maintenance mechanisms of bacterial communities in Gonghai Lake in Ningwu,Shanxi,were investigated by using Q-PCR and DGGE. The results showed that the temperature),p H,dissolved oxygen,electrical conductivity salinity,and ammonium nitrogen( NH4+) contestation were significantly different among the different sampling depths during different months. Bacterial abundance was the highest in August and the lowest in November,and the abundance was higher in the middle water layer( 2 m,4 m,and 6 m depths),but relatively low in the surface layer and bottom layer( 0 m and 8 m depths,respectively). The α diversity index of bacterial communities had significant differences among the different months and depths,and showed an initial decreasing trend and then an increasing trend from April to December. A PERMANOVA test showed that the spatial distribution of bacterial communities was significantly different among depths( P < 0. 001). The results of redundancy analysis and variation partitioning indicated that environmental selection and diffusion limitation had an effect on the maintenance of the diversity patterns of bacterial communities at the different depths of GH. However, the relative effect of environmental factors was stronger,of which the concentration of NO3-,NO2-,and NH4+were the main influencing factors. In conclusion,the bacterial communities in GH subalpine lake showed clear spatio-temporal distribution patterns,and environmental variables had a significant effect on shaping the community diversity.