攀枝花干热河谷区不同海拔高度农田土壤nirS型反硝化细菌的群落结构分析

Community Structure Analysis of nirS Denitrifying Bacteria in Farmland Soil at Different Altitudes in the Dry-hot Valley of Panzhihua

    摘要
  • 摘要:
      目的  探明攀枝花干热河谷地区不同海拔高度农田土壤的反硝化细菌群落结构和丰度特征。
      方法  以攀枝花干热河谷地区1600 m、1800 m和2000 m三个海拔高度的农田土壤为研究材料，通过末端限制性片段长度多态性（T-RFLP）技术分析不同海拔高度农田土壤的nirS型反硝化细菌群落结构和丰度。
      结果  不同海拔梯度农田土壤pH均小于7，土壤有机碳、全氮、速效钾和铵态氮的含量随海拔升高而降低，碱解氮、有效磷和硝态氮含量随海拔升高先增加后降低；群落结构丰富度随海拔增加呈上升趋势，而香侬指数和均匀度呈现出先上升后下降的趋势；T-RFLP分析结果显示，35 bp的T-RFs相对丰度最大，随海拔增加而减少，其次是40 bp的T-RFs，随海拔增加而增加；系统发育分析显示，β-变形菌门为该区域优势反硝化细菌；冗余分析结果显示，土壤硝态氮和有效磷是驱动该区域土壤nirS型反硝化细菌群落组成的主要因子。
      结论  攀枝花干热河谷区不同海拔高度农田土壤中的nirS型反硝化细菌群落结构变化明显 (P < 0.05)，且受土壤硝态氮和有效磷显著影响(P < 0.05)。研究结果可为深入认识干热河谷地区农田土壤反硝化细菌对海拔高度的响应机制提供理论依据。

     

    Abstract:
      Objective  The community composition and diversity of nirS denitrifying bacteria in the farmland soil will be determined at different altitudes in the dry-hot valley area of Panzhihua, so as to provide the basis for further study of nitrogen cycle and soil fertility in this area.
      Method  Farmland soils were collected from the altitudes of 1600 m, 1800 m and 2000 m in Panzhihua dry-hot valleys (DHV), and terminal restriction fragment length polymorphism (T-RFLP) technique was used to analyze the nirS denitrifying bacterial community composition and diversity.
      Result  Soil pH was all less than 7 under different elevation gradients, and the contents of soil organic carbon, total nitrogen, available potassium and ammonium nitrogen decreased along the increase of altitude, while those of available nitrogen, available phosphorus and nitrate nitrogen were increased firstly and then decreased. The richness of nirS denitrifying bacterial community increased with the increase of altitude while the Shannon index and evenness showed a trend of first increasing and then decreasing. The results of T-RFLP analysis showed that 35bp T-RFs was the dominant nirS denitrifying bacteria and its relative abundance decreased with the increase of altitude. 40bp T-RFs was the second largest one and enhanced with the increase of altitude. Phylogenetic analysis showed that β-Proteobacteria was the main denitrifying bacteria. Redundant analysis showed that soil nitrate nitrogen and available phosphorus were the most important factors in shaping the nirS-type denitrifying bacteria community composition.
      Conclusion  The nirS-type denitrifying bacterial communities in the farmland soil at different altitudes in the dry-hot valley of Panzhihua varied significantly (P < 0.05), and significantly related to soil nitrate nitrogen and available phosphorus. Totally, the findings of this study might provide a theoretical basis for deeply comprehending the response mechanism of soil denitrifying microorganisms to soil properties at different altitudes in this dry-hot valley area.

     

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