中文摘要：

【目的】研究烟草成熟期的根际及非根际土壤硝化细菌群落结构和多样性。【方法】运用PCR-DGGE技术对攀枝花市盐边县主要烟区采集的5个烟草根际土样和5个非根际土样进行分析。【结果】所有样品的DGGE图谱表明：各个土壤的硝化细菌群落结构和多样性有较大差异。根际土壤的多样性指数（H）、丰度（S）及均匀度（EH）并非都高于非根际土壤,这可能与烟草成熟期根系分泌物对硝化细菌的抑制有关。不同的土壤类型间的硝化细菌结构有较大的差异。回收的DGGE条带序列结果显示,大部分与冰川、溶岩等极端环境中非培养硝化螺菌属（Nitrospira sp.）相近,而小部分与目前尚未可知的非培养硝化细菌相近。【结论】成熟期的烟草根际土壤中硝化细菌多样性程度总体优于非根际土壤。

英文摘要：

【Objective】The objective of the study is to evaluate the community structure and diversity of nitrobacteria community in rhizosphere and non-rhizosphere soils at tobacco mature stage.【Method】Five tobacco rhizosphere soil samples and five non-rhizosphere soil samples were collected from the main tobacco-producing areas of Panzhihua Yanbian County and analyzed by PCR-DGGE technology.【Result】DGGE analysis showed that nitrobacteria community structure and diversity were different among different soils.Overall,the rhizosphere diversity index（H）,abundance（S） and evenness（EH） were not all higher than those of non-rhizosphere soil,which might be related to rhizosphere secretion at tobacco mature stage which had an inhibitory effect on nitrobacteria.Moreover,the nitrobacteria community structures in different soil samples had a great difference.The recovery DGGE strip series showed that most of them were similar to Nitrospira sp.of the extreme environment such as glacier,or dissolution rock,while small of them were closely related to uncultivated nitrobacteria.【Conclusion】The diversity of nitrobacteria in the mature tobacco rhizosphere soils was higher than that of non-rhizsphere soils.