從市售納豆健康食品中分離篩選出可生產納豆激酶 ( Nattokinase ) 的菌株A,藉由液態搖瓶培養生產納豆激酶,其最適條件以3%黃豆粉、3% 葡萄糖,並額外添加0.5% CaCO3、 0.5% KH2PO4和0.1% MgSO4‧7H2O為培養基,在溫度37℃、180 rpm的條件下進行培養,經醱酵培養48小時之後得到酵素最佳活性值27 U/mL。 批次醱酵試驗結果指出,接種10%的種菌液,以1 vvm 之通氣量,配合300 rpm 的攪拌速度,於37℃下進行放大培養,結果指出菌株A於培養第42 小時出現最佳之酵素活性 ( 81.3 U/mL )。 饋料批次醱酵分為兩階段,第一階段以葡萄糖為主,目的是要提高細胞濃度,接著以黃豆粉為氮源以及酵素生產的誘導劑,在醱酵培養第48 小時出現最佳之酵素活性 ( 330 U/mL )。 在酵素的pH穩定性及溫度穩定性實驗中,粗酵素液之最穩定的pH值在6.0〜7.0,將粗酵素一保存在4℃,1個月後,仍可維持65%的活性。
Abstract We isolate a strain A from natto purchased from the local market. It was employed for the production of nattokinase by shaking culture at 180 rpm and 37 C. The optimum medium for the shaking culture was (g/l) : 3% soybean flour, 3% glucose, 0.5% CaCO3, 0.5% KH2PO4, 0.1% MgSO4.7 H2O. The nattokinase activity of 27 unit/ml was achieved after 48 h shaking culture. The batch fermentation was performed using the same medium as the shaking culture at 300 rpm, 1 vvm of aeration, 37 C. 81.3 unit/ml of nattokinase activity was achieved after 42 h cultivation. Fed-batch fermentation was initialized by using the batch fermentation. Various concentrations of glucose, yeast extract and soybean flour were employed to formulate the feeding medium. 330 unit/ml nattokinase was achieved after 48 h cultivation for the fed-batch fermentation. The crude enzyme was stable at pH 6~7, and 65 % activity retained for the crude enzyme stored at 4 C for 1 month.