Optimization of the cultivation conditions for bacteriocin production of Lactococcus raffinolactis Y-12

Objective: Lactococcus raffinolactis Y-12 was isolated from Dushan pickled Chinese cabbage, and the fermentation conditions of bacteriocin produced from it were optimized.Methods: The factors including fermentation time, temperature, initial p H, glucose and so on, that affected the yield of bacteriocin, were studied in single factor and Plackett-Burman optimization test.On the basis of single factor test and Plackett-Burman treatment, the conditions for bacteriocin production were explored by Box-Behnken design involving the peptone, glucose and initial p H at three levels in combination with response surface methodology. Results: The optimal combination of the medium constituents for bacteriocin production were as follows:fermentation temperature 35 ℃, fermentation time 36 h, inoculums concentration 2%, 10.62 g/L peptone, 31.61 g/L glucose, initial p H6.46, the other composition of MRS medium were unchange.Under the optimal condition, the inhibitory zone diameter was 16.87 mm, than before optimization ( 14.12 mm) to improve 19.5%.Conclusion: The experimental results were in agreement with the prediction values, indicated the established regression model was feasible.