三江源地区高寒草甸土壤氨氧化细菌多样性研究

目的：利用16SrDNA-PCR—DGGE方法首次对青藏高原核心区三江源自然保护区的高寒草甸样地的土壤氨氧化细菌进行了多样性研究。方法：从土壤中抽提微生物总DNA，运用巢式PCR扩增氨氧化细菌16SrRNA基因的V3可变区，结合DGGE（denaturing gradient gel electrophoresis）技术分析样品氨氧化细菌群落组成，并利用相关性分析探讨了群落结构多样性与环境因子的联系。结果：4个样地（玉树S1；囊谦S2；治多S3和S4）共检测到14个多态性条带，多样性指数为1．69～2．00。相关性分析显示多样性指数与海拔、C／N呈负相关，与NO3-呈显著正相关。结论：海拔、C／N及NO3-可能是影响土壤氨氧化细菌多样性的重要因子。

Diversity of Ammonia-oxidizing Bacteria in Alpine Meadow Soil of Sanjiangyuan Natural Reserve

Objective： To study diversity of ammonia-oxidizing bacteria in alpine meadow soil of Sanjiangyuan Natural Reserve in the core area of Qinghai-Tibet Plateau by denaturing gradient gel electrophoresis （DGGE） with PCR-amplification of 16S rRNA genes. Methods： Fourteen polymorphic bands were detected in the four samples with the Shannon diversity index from 1.69 to 2.00. In addition, the AOB diversity index was negatively correlated with the altitude and C/N ratio and positively correlated with the nitrate concentrations. Community genomic DNAs were extracted and used as templates for PCR amplification of the V3 region of the 16S rRNA genes using AOB specific primers. DGGE was used to separate amplified products. Results： A total of fourteen polymorphic bands were detected in those four samples with 9, 9, 7 and 6, respectively for sample S 1, S2, S3 and S4. The Shannon, s diversity indices, which are based on both the number of bands and the intensity of each band, were 1.69 to 2.00 for those four samples with the lowest diversity in S4 and the highest diversity in S 1 of those AOB communities. A correlation analysis （CA） of the AOB diversity index of soil microbial communities and soil physicochemical properties showed that the AOB diversity was positively correlated with the nitrate concentrations （r = 0.874）, and negatively correlated with the altitude （r = - 0.915）, and the ratio of total carbon/total nitrogen （C/N） （r = - 0.813）. Conclusion： The nitrate concentrations, altitude, and C/N ratio might be the important factors to shape soil AOB communities in the Alp prairie at the Sanjiangyuan Natural Reserve. This study provides insights into our understanding of AOB diversity and nitrification potential as well as effects of environmental factors on AOB diversity in alp prairie soil.