关键词: 为提高微生物菌株β-D-葡萄糖醛酸苷酶产酶数量和活性, 缩短发酵产酶时间, 对一株鸡源饲用枯草芽孢杆菌JY24菌株产β-D-葡萄糖醛酸苷酶的发酵工艺和初步催化转化进行研究。采用单因素试验对枯草芽孢杆菌JY24菌株产β-D-葡萄糖醛酸苷酶的产酶条件及培养基成分进行筛选；采用正交试验对培养基组成进行优化分析, 采用HPLC法对酶催化黄芩苷转化试验进行初步研究。试验结果表明, 鸡源饲用枯草芽孢杆菌JY24菌株产β-D-葡萄糖醛酸苷酶最佳产酶条件：发酵时间42 h, 发酵转速240 r/min, 装液量10%, 培养基初始pH 7.0, 发酵温度35 ℃, 接种量4%；最佳产酶培养基组成：蔗糖8.0 g/L, 酵母膏11.0 g/L, 磷酸二氢钾0.38 g/L, 磷酸氢二钾0.38 g/L, 氯化钙0.27 g/L, 硝酸钾0.20 g/L, Tween-20 2.0 mL/L, 玉米浆1.0 mL/L, 黄芩苷1.5 g/L。在此最佳发酵工艺条件下, JY24菌株发酵液β-D-葡萄糖醛酸苷酶酶活性达935.50 U/mL, 较优化前提高25.68倍, 发酵产酶时间缩短2.25~12.25 d, 酶催化初步研究表明黄芩苷转化率为31.20%。

Abstract: In order to improve the enzyme quantity and activity from microbial strains, shorten fermentation time of enzyme production, this article aimed to study the optimization of fermentation process and preliminary catalytic conversion of β-D-glucuronidase from Bacillus subtilis, JY24 strain. Culture conditions for the production of β-D-glucuronidase from Bacillus subtilis JY24 strain were optimized by single factor method; the compositions of culture medium and conversion of baicalin were respectively studied by orthogonal design and HPLC. The result showed that the optimal culture conditions were: fermentation time, 42 h; rotational speed, 240 r/min; 50 mL culture in 500 mL liquid volume; initial culture medium, pH 7.0; temperature, 35 ℃； inoculation amount, 4％. The optimal compositions of medium were: sucrose, 8.0 g/L; yeast extract, 11.0 g/L; KH2PO4 , 0.38 g/L; K2HPO4 , 0.38 g/L; CaCl2 , 0.27 g/L; KNO3, 0.20 g/L; tween-20, 2.0 mL/L; corns steep, 1.0 mL/L; baicalin, 1.5 g/L. Under the optimized fermentation process, the enzyme activity of β-D-glucuronidase of Bacillus subtilis JY24 strain could reach 935.50 U/mL, which was 25.68 times higher than that before optimization, and the fermentation time for enzyme production was greatly shortened by 2.25-12.25 d. The preliminary results of catalytic conversion showed that the conversion rate of baicalin was 31.20%.

Key words: feed, Bacillus subtilis, β-D-glucuronidase, fermentation process, orthogonal design, bioconversion