纳豆激酶液态发酵条件的研究

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,0～12 h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3 232 U/mL,与摇瓶发酵相比,比酶活提高了58%。

Study on liquid fermentation of nattokinase

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 ℃ 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.