Antifungal Substance from Biocontrol Bacillus subtilis B29 Strain

Preliminary study on antagonistic activity of antifungal substance from biocontrol bacterium Bacillus subtilis B29 was made by analyzing the inhibitory effect of cell-free supematant to mycelium growth and conidial spore germination of Fusarium oxysporum f.cucumerinum.The results showed that the antifungal substance secreted by the strain B29 inhibited the growth of Fusarium oxysporium f.cucumerinum and conidial spore germination.The optimum fermentation conditions of antifungal substance from strain B29 were original pH7.5, 75ml/250ml at 30℃ for 120h. The antifungal substance was precipitated by (NH4)2SO4 from 30% to 70%. The crude antifungal substance of strain B29 was stable to heat at some extent, partially tolerant to proteinase K, and more sensitive to trypsinase and pepsin.