【摘要】 为了提高豆豉发酵品质,采用紫外和亚硝基胍方法对产蛋白酶菌株的米曲霉进行诱变处理,以最佳诱变条件筛选得到突变菌株,使其蛋白酶活力提高38.01%,且菌株能够保持较好的遗传稳定性。进一步利用响应面分析法研究培养温度、湿度和时间对该菌株产蛋白酶活力的影响,得到最佳条件为:培养温度42.8℃、湿度84.5%、时间66.6 h,此条件下产酶模型预测值为518.63 U/g,验证实验中产酶活力值为507.87 U/g,表明预测值与实验值拟合良好,达到设计要求,显示诱变所得米曲霉突变株发酵产蛋白酶能力有较大提升。更多还原

【Abstract】 Ultraviolet(UV) and nitrosoguanidine(NTG) were employed to mutate Aspergillus oryzae from fermented soybeans to improve the product quality.The protease activity of the mutant strain was improved 38.01% compared with the original strain and the mutant could keep good hereditary stability.Response surface design was used to explore the effects of incubation temperature,incubation humidity and time on the activity of protease.Results showed that the optimal conditions were incubation temperature of 42.8 ℃,incubation humidity of 84.5% and incubation time of 66.6 h.Under these optimized conditions:the activity of protease would reach 518.63 U/g.The activity of protease of validation experiment reached 507.87 U/g,which was in agreement with the calculated value.It suggested the protease forming capacity of the Aspergillus mutant had been much improved.更多还原