Comparative Studies On Microbial Diversity And Adaptability Of Cyanobacteria In The Different Altitude Lake Of Qinghai-Tibet Plateau

Microbial diversity is the wealth of all mankind, which is the major issue of concernedby all of humanity. Study and protecting microbial diversity is not only to protect andpreserve the global ecological balance and the coordination of ecosystem diversity, but also toutilize the germplasm resources and produce the biological products that benefit for mankind.The degree of microbial diversity is effected by the relationship among micro-organisms andthe interaction between organisms and their environment. The researches on microbialdiversity of Qinghai-Tibet plateau in China are focused on the snow, the ice of the glacier, thefrozen soil and microorganisms in alpine meadow, it is very rare that the study on themicrobial diversity of high elevation lakes.In this study, the seasonal changes of culturable micro-organisms and the total seasonalvariation of all micro-organisms in different altitude lakes of Tibetan plateau were researchedby the methods of microbiological culture, construction of16SrDNA clone library,biochemical analysis, took the different lakes at different altitude as research target, themicrobes in these lakes as material, the relationship among microbes and relation betweenmicrobial diversity and the various ecological factors were analyzed to reveal the effectmechanism of ecological factors to microbial diversity in Qinghai-Tibet plateau Lakes.The research results showed that the number of culturable microorganisms reached themax at August in different altitude lakes, Qinghai Lake and Namco Lake on the Tibetanplateau. The number of culturable microorganisms in Qinghai Lake reached800×107CFU/mland the maximum number of culturable micro-organisms in Namco reached1450×107CFU/ml.The number changes of culturable microorganisms in different altitudes lakes onQinghai-Tibet Plateau were associated with environmental factors. At first, the numberchanges of culturable microorganisms in Qinghai Lake had a significant positive correlationwith light and temperature. The number changes of culturable microorganisms in NamcoLake had a significant positive correlation with water temperature. The climatic andenvironmental factors have a greater impact on culturable microbial diversity in the high-altitude lakes in the Qinghai-Tibet Plateau, which indicated that the climate factors may be animportant adjustment mechanism to maintain its microbe diversity steady-state. The seasonalvariation of ecological factor in different altitude lakes of Qinghai-Tibet Plateau was thebell-shaped change and the change of ecological factors caused by the elevation gradientwas very different.The research results showed that there were some differences in the dominant species inthe three experimental lakes. In the high altitude lakes, the main dominant species wasProteobacteria and Bacteroidetes. The microbial community structure of contrast lakeyuncheng salt lake was Cyanobacteria7.53%, Proteobacteria (alpha and gamma-)9.68%,Actinomycetes8.6%, Bacteroidetes and the other4.35%, Unclassified69.89%, themicrobial community structure of Qinghai lake was Proteobacteria (alpha, beta, gamma-)25.49%, Cyanobacteria1.96%, Actinomycetes1.96%, Bacteroidetes7.84%, Unclassified 62.75%and the microbial community structure of Namtso lake was Proteobacteria (alpha,beta)12.5%, Bacteroidetes19.32%, Verrucomicrobia5.68%, Cyanobacteria3.41%,Actinomycetes3.41%, other1.14%, Unclassified54.55%.The research results also showed that the Cyanobacterias in the high-altitude lakes had abetter ability to adapt to UV-B stress. We found that the contents of ultraviolet shielding andabsording material, such as Scytonemin, MAAs and algal blue protein in the Cyanobacterias ofhigh-altitude lakes were higher than that in the Spirulina of lower altitude, which irradiated byUV-B stress after training. At the same time, Cyanobacterias, isolated from the high-altitudelakes, was more sensitive to UV-B stress response than others.