Optimization of the fermentation conditions for the production of antigugal protein by strain Bacillus polymyxa against Verticillium dahliae

In order to increase the quantity of antifungal protein from Bacillus polymyxa 7-4,the strain was cultured under different conditions.Through single factor experiments,the suitable carbon source,nitrogen source and inorganic salt were chosen.The optimal composition of media was determined by orthogonal experiments.The optimization of fermentation factors,such as initial pH,fermentation temperature and fermentation time,was made by single factor experiments.By orthogonal design,the optimal proportions of fermentation medium were glucose 5.0%,soy peptone 5.0%,MnSO4 0.02%,MgSO4·7H2O 0.10%.By single factor experiments,the optimal fermentation condition was initial pH 7.5 and inoculum age of 10～12 hours,shaking flask fermentation temperature is 30℃ for 48 hours under the conditions,the most quantity of antifungal protein was obtained.After optimization,diameter of inhibition zone was increased by 50.4%.