Research Of Molecular Ecology On Both Ammotnia Oxidizing Bacteria And Nitrite Oxidizing Bacteria In Alpine Glassland Soil Of Sanjiangyuan Natural Reserve

Sanjiangyuan Nature Reserve which is headstream of Yellow River, Yangtse River and Lantsang River, has high biodiversity and important ecological function, and is important for sustainable development of middle and lower river reaches. Meanwhile, it is very sensitive to ecological interference. The research on the distribution and regional character of soil microorganisms in this area is meaningful to evaluate its ecological environment, understand the influence of global change on this area and offer scientific data for constituting the protected policy. In this study, we detected and analyzed the soil physicochemical properties and the soil enzyme activity of thirteen samples in Sanjiangyuan Nature Reserve. Denaturing gradient gel electrophoresis (DGGE) and sequencing were used to investigate the diversity and community structure of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). Besides, the microbial diversity of AOB and NOB living in different environments and altitude, as well as the major factor of influence on the diversity were discussed. The key results from these studies are summarized as follows:Organic matter, soil N and P contents were high, and K, P and Ca contents were abundant in all samples. Activities of soil urease, sucrose, amylase, cellulase, polyphenoloxidase and catalase in four forest lands were low. Both the activities of soil sucrose, amylase, cellulase, urease, catalase and contents of water, organic matter, total N, total P were higher in soil of alpine meadow than those in soil of alpine glassland. On the contrary, the polyphenoloxidase activity, pH, and the calcium concentration were lower in soil of alpine meadow than those in soil of alpine glassland. The altitude was negatively correlated with the activities of urease, sucrose, amylase, catalase, and contents of organic matter, total P, total N.In this study, we used DGGE to reveal the AOB community structure of soil samples taken from thirteen sites in Alp prairie of Sanjiangyuan Natural Reserve. Nineteen polymorphic bands were detected in those samples with the Shannon diversity index from 1.45 to 2.40. Sequencing of those DGGE bands showed that more than 70% were highly similar to Nitrosospira sp., suggesting that Nitrosospira sp. may play important roles in this ecosystem. Also, each site had its own specific AOB populations. The CCA results indicated that, the nitrate concentrations, altitude, and C/N ratio might be the important factors to affect soil AOB communities in the Alp prairie at the Sanjiangyuan Natural Reserve.To understand the community structure of NOB in the soil of Sanjiangyuan Natural Reserve, DGGE was used to separate the amplified products and analyze the 16S rRNA gene diversity of the thirteen samples. Twenty polymorphic bands were detected in those samples with the Shannon diversity index from 1.46 to 2.31. Result of sequencing nine dominant bands showed that seven out of nine bands had high sequence similarity to the Nitrospira sp., and the others showed high sequence similarity with the uncultured bacterium isolating from DGGE bands. Canonical correspondence analysis (CCA) combining the DGGE patterns and physicochemical parameters indicated that the soil pH, moisture, the calcium and nitrate concentrations, and total P content significantly influenced the NOB community.