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

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.