Fermentation Conditions of Antagonistic Strain XL12 against Alternaria alternate

In order to increase the quantity of antifungal protein from Bacillus subtilis XL12,the strain was cultured under different conditions.The optimization of fermentation factors,such as the C/N proportion of basic medium,inoculation amount,initial pH,fermentation temperature and fermentation time,was made by single factor experiments.The result showed that the optimal fermentation condition was initial pH 6.95~7.05 and shaking flask in 220 r·min-1speed,fermentation temperature was 30~35℃ for 72 hours,premise of which the C/N ration is 30∶1,inoculation amount is 0.5%,under the conditions,the most quantity of antifungal protein was obtained by the 70%(NH4)2SO4salting out supernatant fluid of strain XL12 fermentation.