开菲尔粒中高产蛋白酶菌株的筛选及培养基优化

Screening of High Protease-producing Bacteria of Kefir Grians and Optimization of Fermentation Media

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。

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.