Spatio-Temporal Patterns And Driving Mechanism Of Bacterial Communities Biodiversity In Lakes,Ningwu,Shanxi

The lakes ecosystem in North China are decaying impacted by human activities and climate change,leading to corresponding change of biodiversity and structure of microbial communities.Further study on the mechanism of the impact of environmental factors on the diversity and function of microbial communities can provide a basis for clarifying the response mechanism of lake ecosystem to climate change and human activities.The spatial-temporal dynamics and the diversity maintenance mechanism of bacterial communities in mountain lakes in Ningwu,Shanxi,were investigated by using high-throughput sequencing,q-PCR and DGGE.The spatial-temporal dynamics and driving mechanism of denitrifying bacteria communities abundance in lake communities were investigated by q-PCR with the denitrifying genes?nirK and nirS?as markers.The results show that:?1?the physical and chemical parameters of water were significantly diffirent among the lakes?P<0.05?,most of which had the same trends in different seasons.The p H value of PPH was the lowest?6.864?,while the organic carbon content was the highest?27.856 mg/L?;the ion concentration of GH was highest,while that of MYH lake was relatively low.?2?the?-diversity index of bacterial communities showed significant differences between seasons and sites,which were mainly related to the ?P<0.05?.The composition of bacterial communities in different lakes and seasons was significantly different,which was mainly affected by the pattern of bacterial communities structure in lakes was obviously affected by environment selection and diffusion restriction,and environment selection is the main driving force,among which nitrogen concentration,DO,electrical conductivity?EC?and temperature?T?were the main factors affecting the diversity of bacterial communities in lakes.?3?in Gonghai lake,the abundance of bacterial communities had significant spatio-temporal dynamic characteristics.The highest abundance in copies m L^-1;the surface layer and bottom layer?0 m and 8 m?are relatively ommunities showed significant differences between months and depths?P<0.05?,and showed a trend of initial decreasing and then increasing from April to December.The results of PERMANOVA analysis showed that the?-diversity of bacterial communities was significantly different among depths?P<0.001?.The results of redundancy analysis and variance decomposition showed that the?-diversity pattern of bacterial communities was resulted from both environmental selection and dispersal limitation,and the relative effect of environmental selection was stronger,in which the concentration of inorganic nitrogen was the main influencing factors.?4?the abundance?copy number?of nirK and nirS genes in the lakes ndicating that the abundance of denitrifying bacteria communities encoding nirK and nirS was higher in the lakes of Ningwu.The abundance of nirK gene was significantly higher than that of nirS gene in all lakes,which indicated that the bacterial communities with nirK gene might play a more important role in the reduction of nitrite than that with nirS gene.?5?the dynamic characteristics and driving mechanism of denitrifying bacteria abundance.There was a significant difference in the abundance of denitrifying bacteria communities containing nirK and nirS functional genes among the three lakes?P<0.05?.The abundance of denitrifying bacteria communities in each lake had significant seasonal variation?P<0.05?.This change is mainly related to environmental factors.The results of stepwise oncentrations in different seasons had the most significant effect on denitrifying bacterial communities?P<0.05?.This showed that although most of the denitrifying microbial communities containing nirK and nirS genes were positively correlated with each other,their responses to environmental factors were different,which reflecting the differences in the adaptive mechanism of these bacteria communities to environmental changes.This study provides data support for revealing the response mechanism of subalpine lake ecosystem to climate change and human activities,and is of great significance for management of inland lake water resource and sustainable utilization.