| The fermentation condition of the Lactobacillus ALAC-3 to produce inhibiting yeast substance was studied, which was isolated from traditional fermentation food in Inner Mongolia. In this study, the best medium was chosen from eight culture media. Then the best components and its volume were confirmed by Single-Factor experiments and Orthogonal experimental design. The culture time, culture temperature and initial pH of medium were optimized using Box-Behnken design and response surface methodology. The results were showed as follows:(1) The carbon source and nitrogen source significantly affected the production of inhibiting substance, and metal ion and growth factor did not. The best medium was composed as follows:25 g/L of sucrose,20 g/L of peptone-beef extract-yeast extract (2:1:1),0.1 mol/L of K+-Mg2+-Mn2+(10:3:1),2 ml/L of ethanol as growth factor.(2) In all of culture parameters, culture time and temperature had significant effects on inhibiting activity, and inoculum size and initial pH did not have significant effects. The regression equation was obtained:inhibition zone(mm)=34.78-0.063*A-0.17*B +2.95*C+0.17*A2-0.073*B2-5.76*C2-0.16*A*B+0.20*A*C-0.12*B*C, R2= 0.997. The optimal conditions was culture time of 30 hours, culture temperature of 31℃, initial pH of 6.6.(3) Under the best conditions, the response value (diameter of inhibition zone) was 35.14 mm, increased by 17.5% than that before optimization. |
