Optimization of fermentation conditions for antiaflatoxin ingredient by marine actinomycete strain MA03 using sweat potato residue with response surface methodology

Marine actinomycete strain MA03 produced some active ingredient with antiaflatoxin activities. To obtain the optimal fermentation conditions and develop the reutilization of sweet potato residue,the strain MA03 was cultured in the liquid medium supplemented with sweet potato residue. Three main factors(the concentration of sea water,the concentration of(NH4)2SO4and the inoculum size) affected the yield of antiaflatoxin ingredients were screened by Plackett-Burman designed using Design-Expert 8.0.6. Steepest ascent experiments involving these three factors were performed for approaching their optimal response region,and then Box-Behnken design was used to optimize the critical internal factors. Finally,the optimal concentration of the variables were determined as follows:sea water 0.64%,(NH4)2SO43.47‰,inoculum size 8.44%,sweet potato residue 3%,sucrose 2%,Mg SO40.1‰,initial p H 8.5,fermentation temperature 28℃ and fermentation time 10 d. The antiaflatoxin rate was predicted as 97.62% under this condition. This model was confirmed subsequently,and the antiaflatoxin rate was 96.24% ±0.38%,which was close to the predicted value. These results indicated that this predicted model had high reliability,and could be used in optimization of antiaflatoxin ingredient production of marine actinomycete strain MA03.