纳豆激酶液体发酵条件的优化

Optimization of Liquid Fermentation Conditions of Nattokinase

以纳豆枯草芽孢杆菌(Bacillus subitilis natto)为出发菌株,对其液体发酵生产纳豆激酶(Nattokinase,NK)的培养基组成(碳源、氮源、碳氮比和金属离子组成)和培养条件(温度、pH值,发酵时间、接种量和装液量)对产酶量的影响进行了研究。结果表明:液体发酵培养基的最佳碳源为木糖,浓度为1.5%;最佳氮源为大豆蛋白胨,浓度为2.0%;添加无机盐组分为MgSO40.05%、CaCl20.02%、K2HPO4/KH2PO40.1%/0.1%。发酵培养的最佳温度为37℃,pH 7.0时有利于菌体产酶,最适装液量为100 mL/250mL,接种量以2%为最佳,最适种龄为18 h;发酵周期为3 d。通过优化培养基和发酵条件,产酶量达到1 081 U/mL。

Liquid fermentation for nattokinase by Bacillus subitilis natto BSN was investigated. The components of its culture medium including carbon source, nitrogen source, the ratio of carbon source to nitrogen source and ion composition were studied. The results showed that the fermentation conditions included temperature, initial pH value, fermentation time, inoculation quantity and volume of the medium. To fermentative medium, the best carbon source was xylose 1.5 %, and the best nitrogen source was soya peptone 2.0% .The components of inorganic salts were MgSO4 0.05%, CaCl2 0.02%, and K2HPO4/ KH2PO4 0.1%/0.1%. 37℃ was the most suitable temperature for the production of NK. The strain had the biggest speed of growth and the highest yield of NK under pH7. The volume of media was 100 mL/ 250 mL which was chosen for the most gross production of NK. 2% of 18 h-old inoculum was the best condition for NK＇s production. After the system optimization, the yield of nattokinase of 1 081 U/mL was obtained at the optimized medium and optimized conditions.