| The Qinghai-Tibet Plateau is a very typical extreme environment area. Its high altitude,low air temperatures and high UV radiation intensity make it very high research value in the ecological environment and species diversity. The microbial diversity in the representative waters of the Qinghai-Tibet Plateau is influenced by the environment of the Qinghai-Tibet Plateau, which has very high indicating effect on the ecological environment and species diversity in the waters of the Qinghai-Tibet Plateau. The research on microbial diversity in the waters of the Qinghai-Tibet Plateau has important theoretical research value on better assessment of microbial diversity and the relationship between the environmental changes and the microbial diversity in lake water ecosystems at high altitude.In this study, the microbial diversity, the environmental factors and the correlation between the microbial diversity and the environmental ecological factors in the lakes of Qinghai-Tibet plateau at different altitudes and the surface sediments in the part of the lakes were studied. The research results provided a basic scientific data for the further study on the development of microbial diversity in high altitude lakes. The samples collected from Yuncheng Saline Lake, Qinghai Lake, Nam-Co Lake and the surface sediments of Qinghai Lake were served as the study material, the microbial community species diversity, the microbial community functional diversity and the relationship between microbial community functional diversity and environmental ecological factors in the water and surface sediment samples were studied by using plate-counter method, Biolog technology and Miseq macro genome sequencing technology in this study. The main results were as follows:(1)The analysis of lake water samples at different altitudes in Qinghai-Tibet Plateau was done by using the technique of Miseq macro genome sequencing, the results showed that the microbial community richness and community diversity of Qinghai Lake in October(Q10)and in August(Q8) were the highest. And the microbial community richness and community diversity of Nam-Co Lake in April(N4) were the lowest. The similarity of microbial species in Qinghai Lake and Nam-Co Lake was analyzed, and the results showed that the microbial species was with a very high similarity, and the dominant bacteria group mainly focus on Bacteroidetes, Proteobacteria, Actinobacteria, Verrucomicrobia, Firmicutes, Planctomycetes,Cyanobacteria. The correlation between microbial diversity and environmental ecological factors was analyzed, and the results showed that the microbial community diversity was mainly affected by water temperature, UVB and pH, and negatively correlated with water temperature, UVB and pH in Qinghai Lake and Nam-Co Lake. Among them, the influence ofpH on community diversity was greatest, and the water temperature was the least.(2)The number of cultivatable microorganisms in the surface sediments of Qinghai Lake was analyzed, the results showed that the number of cultivatable bacterial and fungal colonies in the surface sediments in 0~5cm layer and 5~20cm layer were significantly influenced by the seasonal changes(P<0.05). The number of cultivatable bacterial colonies in0~5cm layer and 5~20cm layer reached the maximum value in August, which were 1.28×108CFU and 1.8×108 CFU respectively. The number of cultivatable fungal colonies in 0~5cm layer reached the maximum value in October and in 5~20cm layer reached the maximum value in June, which were 1.32×10~5 CFU and 3.58×10~5 CFU respectively.(3)The results of Biolog-ECO plate experiment showed that the functional diversity of microbial community in the surface sediments of Qinghai Lake was seasonal variation, and its size ordering was sorted as follows: August > June > October > April > May.(4)The results of Miseq macro genome sequencing of surface sediment samples from Qinghai Lake showed that the microbial community richness of the sample was the largest in May(2a), and the diversity of the samples was the largest in August(4a) in the 0~5cm layer,the microbial community richness of the sample was the largest in October(5b), and the diversity of the samples was the largest in August(4b) in the 5~20cm layer. The statistical results of dominant bacteria showed that comparing with the dominant bacteria in the 0~5cm layer, the ratio of Proteobacteria in the 5~20cm layer was higher, and the ratio of Bacteroidetes in the 5~20cm layer was lower. Both in the 0~5cm layer and the 5~20cm layer,the ratio of Acidobacteria, Actinobacteria, Firmicutes, Gemmatimonadetes and Verrucomicrobia were basically the same, and the proportion was low. During June and August, the ratio of Planctomycetes significantly increased.(5)The results of correlation analysis between the environmental ecological factors and the microbial community showed that the number of cultivatable microorganisms and the microbial community diversity were mainly influenced by water temperature, air temperature and the illumination intensity, which was positively correlated with the number of microorganisms and negatively correlated with microbial community diversity. Among them,UVB and illumination intensity had the greatest influence on the proportion of dominant bacteria, and the influence of pH was the least. |
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