[关键词]
[摘要]
采用脱脂乳粉平板初筛法,从开菲尔粒中分离得到10株有明显水解圈的蛋白酶产生菌,对脱脂牛奶平板上透明圈/菌落直径比(HC)>2.00的KX-1、Kx-3、Kx-7三株菌通过时间-酶活曲线进行复筛,得到酶活最高(发酵30 h、酶活146.43 U/mL)的菌株Kx-7。利用单因素试验对培养基进行优化,在此基础上利用Plackett-Burman (PB)试验设计法对影响蛋白酶活性的重要因素进行筛选,结果表明果糖,酪蛋白和Triton X-100,3个因素对产酶影响显著。
[Key word]
[Abstract]
Ten strains,which could produce protease and had obvious hydrolysis circles on defatted milk powder plate,were isolated from Kefir Grians. Three strains KX-1, Kx-3, Kx-7, which ratio of transparent circle diameter to colony diameter was higher than 2.00 on defatted milk plate,were used to be isolated again through time-enzyme activity curve. The strain Kx-7 had the strongest protease activity (reached 146.43 U/mL) when fermented for 30 h. Single factor experiments were used to optimize the medium at first followed with the most important factors selection with Plackett-Burnan (PB) design. The results revealed that three important factors (fructose, casein and Triton X-100) had significant effects on protease production from Kx-7.
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[基金项目]
科技部"十二五"科技支撑计划项目(2012BAD28B07);上海市科委科技开发项目(12DZ2281400)