考察纳豆杆菌在7.5 L发酵罐中分批发酵产纳豆激酶的条件,纳豆激酶酶活采用四肽底物测定.结果表明:纳豆杆菌生长和产酶的适宜条件不一致.发酵过程中发酵罐搅拌转速控制为500 r/min不变,0～12h时控制pH为8.0、温度为37℃；12～36 h调整pH为7.0、温度为30℃；16 h时补加外源C源,连续发酵36 h.该过程中发酵液中比酶活最高达到3232 U/mL,与摇瓶发酵相比,比酶活提高了58％.%In order to investigate the effects of fermentation conditions of nattokinaseline i. e. agitation speed, temperature, pH, fermentation time, feeding and phase control) , the fermentation was carried out in a 7. 5 L fermenter. The enzyme activity of NK was determined by the tetra-peptide ( Suc-Ala-Ala-Pro-Phe-pNA) as substrate. The results showed that the appropriate conditions of Bacillus subtillis natto growth and enzyme production were inconsistent. The agitation speed was controlled at 500 r/min in the fermentation process, and three stages were studied, i. e. pH 8. 0, temperature 37 t at 0 - 12 h, pH 7. 0, temperature 30 ? at 12 -36 h, adding carbon source after 16 h, then a continuous fermentation for 36 h. The enzyme fibrinolytic activity reached 3 232 U/mL, which was increased by 58% in contrast with that of liquid fermentation in flask.
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