Isolation and identification of antagonistic Bacillus spp. against Verticillium dahliae: the antibacterial properties of two strains

Cotton Verticillium wilt is the most serious fungal disease in Chinese cotton production, screening for its control for stable and high yields is of great significance in China. We have isolated antagonistic Bacillus strains against Verticillium dahliae from healthy continuously-cropping cotton rhizosphere soil in Xinjiang. A total of 146 strains were obtained and 29 strains showed varied degrees of antagonism to Verticillium dahliae. Of these strains J-02 and J-29 belonged to Bacillus pumilus and the remainder are similar to B.subtilis. We found that the strongest inhibition of J-02 on Verticillium dahliae was in decline phase, J-15 instable phase and inhibition was stable in the pH range from 5~9 for J-02 and 7~9 for J-15 respectively. Strain J-02 was found to be more resistant to heat, J-15 was sensitive to temperature, but there was still an inhibition zone after 100℃ treatment J-02 inhibited the germ tube of Verticillium dahilae e-longates to form mycelium. J-15 caused mycelium of Verticillium dahliae to be deformed, and to fail to produce spores. In pot experiments, J-02 and J-15 showed acertain protective effect on cotton Verticillium wilt. In conclusion, strains J-02 and J-15 have potentials as biocontrol vectors against cotton Verticillium wilt.