纳豆芽孢杆菌的分离鉴定及纳豆激酶高产菌株的筛选

Indentification and screening of high nattokinase activity producing strains of Bacillus subtilis Natto

分别从北京、大连和日本三个产地的纳豆食品中分离纯化得到了9个具有纳豆芽孢杆菌典型菌落特征的芽孢杆菌单菌落,与模式菌株纳豆芽孢杆菌N1株分别从菌落形态、个体形态和生理生化试验三方面进行对比鉴定,结果表明,其中5株芽孢杆菌为纳豆芽孢杆菌。将这5株纳豆芽孢杆菌分别在酪素平板上划线初选,得到了298株具有蛋白酶活力的菌株,从中筛选出活性最高的5株命名为:NB、NC、ND、NE和NF,测定各株发酵液的纳豆激酶酶活力,结果表明NB、NC和ND3株具有较高纳豆激酶活性,酶活力分别达到了1041.37、1125.13和1804.64IU·mL-1。

Nine Bacillus subtilis strains were isolated from three Natto food produced in Beijing, Dalian and Japan, respectively. Compared with model strain Bacillus subtilis Natto N1, five strains were identified as Bacillus subtilis Natto according to their morphological, physiological and biochemical characters. Five highest protease activity strains named NB, NC, ND, NE and NF were screened by casein-plate method from 298 strains of protease-producing strains. Finally, NB, ND and NE were selected from the examined strains for their high level of nattokinase-producing activity. The nattokinase activity of these three strains were up to 1 041.37, 1 125.13 and 1 804.64 IU .mL^-1, respectively.