响应面法优化红曲米中凝乳酶高产菌株的发酵条件

Optimization of the fermentation conditions of high chymosin-producing strain from red kojic rice with response surface methodology

对从红曲米中分离得到的产凝乳酶能力强的菌株M5传代菌株的液态发酵培养基及产酶条件进行优化。首先进行单因素实验得到适宜的氮源为(NH4)2SO4、酪蛋白,无机盐为FeSO4、KH2PO4,适宜的接种量为1%,培养温度为30℃,培养时间为5d,发酵培养基初始pH为6.0。在此基础上通过Plackett-Burman实验筛选出对酶活影响显著的三个因素:(NH4)2SO4含量、培养时间和培养温度。再用Box-Behnken响应曲面实验对三个显著因素进行优化。结果表明,产酶的最佳培养基组分:(NH4)2SO40.53%、FeSO40.05‰、KH2PO40.05%、干酪素0.5%、葡萄糖2%、接种量1%。最佳发酵条件为:培养温度31.3℃、摇床转速为180r/min、培养时间113h、pH6.0。基于响应曲面优化的产凝乳酶培养基组成与发酵条件效果显著,供试菌株M5传代菌株所产凝乳酶活性由45.34SU/mL提高到190.68SU/mL。

The chymosin-producing medium and fermentation conditions of M5 reproduction strain from red kojic ric was optimized. First,the single factor test showed that the suitable nitrogen source was （NH4）2SO4 and casein, inorganic salt was FeSO4 and KH2PO4,inoculums was 1% ,culture temperature was 30℃ ,incubation time was 5d,fermentation medium initial pH was 6.0. The main factors effected chymosin activity was （NH4）2SO4 incubation time and culture temperature by Plackett-Burman method and the optimum conditions of the main factors were determined by means of response surface analysis. The highest yield of milk-clotting enzyme was achieved by using （NH4） 2SO4 （0.53%）, FeSO4 （0.05%o）, KH2PO4 （0.05%）, casein （0.5%）, glucose （ 2% ）, inoculums （ 1% ）. Fermentation conditions were： culture temperature 31.3℃, speed 180r/min, incubation time 113h, pH6.0. Results based on the response surface were obvious. Chymosin activity increased from 45.34SU/mL to 190.68SU/mL.