nifH gene diversity and community structure of soil nitrogen-fixing bacteria in Hulunbeier grassland,Inner Mongolia
Polymerase chain reaction-denaturing gradient gel electrophoresis and sequence analysis were adopted to assess the nifH gene diversity and community structure of soil nitrogen-fixing bacteria in five types of grassland ( Filifolium sibiricum steppe , Stipa baicalensis steppe , Leymus chinensis steppe , S. grandis steppe , and S. kryrowi steppe) in Hulunbeier. The nifH gene diversity of nitrogen-fixing bacteria was the highest in L. chinensis steppe, followed by in S. kryrowi , S. grandis, S. baicalensis , and F. sibiricum steppes. The community composition of nitrogen-fixing bacteria differed significantly with grassland type. In L. chinensis steppe, the community composition of nitrogen-fixing bacteria had high similarity with that in S. grandis steppe, but the similarity among other three grassland types was lower than 60％. Phylogenetic analysis showed that most nitrogen-fixing bacteria were Alpha-proteobacteria of Proteobacteria, belonging to Bradyrhizobium, Mesorhizobium , Rhodopseudomonas , and Azospirillum , respectively. In the 5 grassland types, free-living nitrogen-fixing bacteria and associative nitrogen-fixer were the major ecotypes in S. kryrowi steppe, while symbiotic nitrogen-fixer was the dominant ecotype in other four grassland types.
国家科技期刊平台
NSTL
万方数据
维普
