高产蛋白酶纳豆芽孢杆菌的分离筛选与鉴定

Screening and Identification of a High Protease Producing Bacillus subtilis Natto Strain

以北京、大连和日本3个产地的纳豆产品为试验材料,从中筛选可用于畜禽生产的纳豆芽孢杆菌(Bacillus subtilis natto)蛋白酶高产菌株。先通过酪蛋白平板初筛得到9株芽孢杆菌,再以N1型纳豆芽孢杆菌为模式菌株,对初筛得到的菌株进行菌落和菌体形态观察、生理生化鉴定,确定有5个菌株为纳豆芽孢杆菌。测定5个菌株48 h发酵液中蛋白酶活性,结果表明:菌株NB1为蛋白酶高产菌株,发酵液中蛋白酶活性为19.41 U.mL-1,产蛋白酶特性在6代内可保持稳定。

A strain of protease producing Bacillus subtilis natto was screened from natto foods which were produced in three places. 9 Bacillus were first screened with casein plate, and 5 strains were identified to be Bacillus subtilis natto by morphological, physiological and biochemical characters with Bacillu subtilis natto N1 as the model strain. A strain named NB1 was selected with the highest protease activity （19.41 U·mL^-1） through the test of protease activity in the 48h fermenting medium among the 9 strains. The stability of its protease producing is stable in 6 generations.