Isolation and identification of nitrogen fixation strains from rhizosphere of Kentucky bluegrass

The nitrogen free culture medium (NFM) was employed for isolating and purifying nitrogen-fixing bacteria strains from Kentucky bluegrass rhizosphere. Twenty one pure cultures of nitrogen-fixing bacteria strains were obtained and their physiological and biochemical characters were determined in this study. The result indicated that the strains ranking in Azoobacter, Pseudomonas, Bacillus, and Enterobacter. The physiological characters of them were rhabditiform and near-spherical, and few strains (N1,N5,N8,N16) produced gemma. For these nitrogen-fixing bacteria strains, the catalase and lysozyme tests showed positive and the hydrolyzed pectin and indole test showed negative. All strains cannot survive in the pH 5.7 nutrient broth. Most of strains were aerobes except with N13 and N14.