Abstract: H/C(transparent circle diameter/colony diameter) taken as indicator,nine protease-producing strains were isolated from the Japanese traditional natto food,which cultured in soybean milk powder mixed with milk powder.Folin-phenol method used for detecting the protease activity of the fermented supernatant,and the highest protease activity strain H2 was selected,which was identified as Bacillus subtilis sub.natto according to morphological and physiological characteristics.In order to investigate the effect of initial medium pH,temperature,broth content,inoculation amount and seed age on protease activity of H2 strain,single factor experiment has been done.The results showed that the best conditions were: initial medium pH7,incubation temperature 40 ℃,broth content 40 mL/250 mL,3% inoculation amount and seed age 25h.
王素英,田立丹,沈亚薇,等. 纳豆菌的分离、鉴定及产蛋白酶液态发酵条件的优化[J]. 食品与发酵工业, 2011, 37(06): 74-77.
Wang Su-ying,Tian Li-dan,Shen Ya-wei,et al. Isolation and Identification of Natto Bacteria and Optimization of Liquid-Fermentation Conditions for Protease Producing[J]. Food and Fermentation Industries, 2011, 37(06): 74-77.