氮肥对小麦田土壤nirS型反硝化细菌多样性的影响

Diversity of nirS-type denitrifying bacteria under different nitrogen fertilizer management in wheat soil

【目的】研究施用无机氮肥对小麦田土壤nirS型反硝化细菌多样性的影响。【方法】通过构建反硝化细菌亚硝酸盐还原酶nirS基因克隆文库,采用限制性片段长度多态性(Restriction Fragment Length Polymorphism,RFLP)技术分析了施氮肥处理和不施氮肥处理土壤中nirS型反硝化细菌的多样性。【结果】两种处理各自分别得到了27个可操作分类单元(Operational Taxa Units,OTUs),其中有9个OTUs在两个处理中相同。虽然两种处理中nirS反硝化细菌的香农-威纳指数,Simpon指数,丰富度指数,均匀度指数相近,但是土壤的OTU类型发生了很大变化。通过对施氮肥处理nirS文库中11个代表性nirS克隆子的序列分析,有10个克隆子与数据库中的nirS序列的相似度在73%～95%之间,有1个序列在数据库中找不到相似序列。【结论】施氮肥在短期内显著改变了土壤中nirS型反硝化细菌群落结构的构成。

[ Objective] To study the effect of inorganic nitrogen fertilizer on nirS-type denitrifiers＇ community in the wheat soil. [Methods] We constructed nirS gene libraries of two different treatments of soil： soil fertilized with inorganic nitrogen fertilizer （B-UN） and without nitrogen fertilizer （B-NN）. And we used restriction fragment length polymorphism （RFLP） method to analyze the nirS-type denitrifiers＇ diversity. [Results] There were 27 operational taxa units （OTUs） in each treatment after Msp I and Afa I digestion and only nine OTUs existed in both treatments. The ecological indexes such as Shannon-Wiene index, Simpon index, richness index and evenness index of two different soils were nearly equivalent. However, significant difference was found between the OTU clusters from clone libraries of different treatments. Eleven representative clones were sequenced. The similarities of ten sequences were from 73 % to 95 % to the sequences of the database. There was one sequence which had no similar nucleotide identities in database. [ Conclusion] The application of inorganic nitrogen fertilizer altered significantly the nirS-type denitrifiers＇ community in the wheat soil.