Abstract:

Dozens of strains of bacteria were isolated from the surface of fruits and the soil, they were selected through the plate confrontation method and six strains which have good antagonistic effect are obtained, among them two strains named T3 and T8 which the fermentation broth showed a significant antagonistic effect to Penicillium expansum are found. The antifungal activity of fermentation broth of T3 and T8 are studied. The stability experiment show that after treatment with 100 ℃ and two proteases, the fermentation broth of T3 performs good antagonistic effect, while antagonistic effect of the fermentation broth of T8 decreases a lot. The antifungal activity of T3 and T8 reach almost highest level after 2 days growth. It is also found that BPA was the optical medium to T3 and PDA was the optical medium to T8. The fermentation broth of two strains can cause hyphae deformity of Penicillium expansum. According to their morphological, physiological, biochemical characters, and the analysis of the sequence of 16SrDNA,T3 and T8 were preliminary identified as Bacillus subtilis, two strains of the similarity between the gene sequence is 93.45%.