文摘
The strain Bacillus subtilis B2 isolated from a Chinese traditionally fermented food was capable of producing ¦Á-glucosidase inhibitor (AGI). On the basis of single-factor experiments, the optimum culture conditions using okara as the substrate were achieved by response surface methodology (RSM). The experimental results lead to the conclusion that the highest yield of AGI was reached at the fermentation time 65.6 h, fermentation temperature 39.0 ¡ãC, Okara concentration 4.5 % and pH 7.11. A second-order model developed for the production of AGI prediction exhibits a F-value of 15.8 and a high value for the coefficient of determination (R2 = 0.933). Under these conditions, the AGI activity of the broth reached 29.4. In comparison with the highest AGI activity (24.3) obtained at the one-factor-at-a-time fermentation condition, the AGI activity increased by 21 % . The AGI in the fermentation broth of B. subtilis B2 was also partially purified and determined by HPLC-ELSD. One of effective AGI, deoxynojirimycin (DNJ) has been proved in the fermentation broth, which indicated that the fermented okara might be considered as one of the promising materials for producing the food-derived DNJ products.