Abstract: Soil bacteria were isolated from the rhizosphere of Stipa plants in alpine grassland of Qinghai province, China. Antifungal activity of the isolated bacteria was determined using the plate confrontation method for Alternaria solani, Fusarium avenaceum, Phoma foveata and Colletotrichum coccodes, and the bacteria were identified by 16S rDNA sequence analysis. The results showed that 23 strains of bacteria were isolated, and 17 of these strains could be sub-cultured. The soil bacteria count was between 6.4×10⁶ and 36×10⁶ cfu·g^-1. Four bacterial strains (17.39% of isolated taxa) designated 4T1, 5T1, 10T1 and 10T3 had an antagonistic effect on more than one tested fungus, and the degree of inhibition was between 46.68% and 75.71%. Strain 10T1 had a notably strong antifungal effect, with the inhibition levels to A. solani, F. avenaceum, P. foveata and C. coccodes being 67.14%, 68.57%, 61.43% and 75.71%, respectively. The size of this strain ranged between 3.79 μm×0.85 μm and 10.50 μm×2.37 μm and the organism is Gram-positive, and rod-shaped. Combining information about culture characteristics, morphological characteristics and 16S rDNA sequence analysis, the 17 strains of soil bacteria isolated were identified as belonging to 7 genera and 12 species, of which Bacillus was the dominant genus. Of the strains isolated, 8 strains (47.05% of isolated strains), were identified as Bacillus. In summary, several isolated soil bacteria from the rhizosphere of Stipa plants in the alpine grassland of Qinghai, displayed significant antifungal activity and could potentially provide microbial resources for the development of biocontrol agents.

Key words: alpine grassland, soil bacteria of rhizosphere, screening, antagonistic function, identification