响应面法优化巨大芽孢杆菌Y103产普鲁兰酶的培养条件

Optimization of fermentation conditions for pullulanase production by Bacillus megaterium Y103 using response surface methodology

在玉米秸秆腐殖质土壤中筛选分离得到一株巨大芽孢杆菌(Bacillus megaterium)Y103,采用单因素试验、响应面法优化巨大芽孢杆菌Y103产普鲁兰酶的培养条件。结果表明,最佳培养基配方为糯米淀粉8.5 g/L,酵母膏13.3 g/L,蛋白胨26.7 g/L,KH2PO40.5 g/L,MgSO4·7H2O 0.1 g/L,MnSO4·7H2O 0.05 g/L,NaCl 2.0 g/L。最佳发酵条件为初始pH8.8,发酵温度21℃,发酵时间55 h。在最优条件下,普鲁兰酶酶活力为(0.77±0.03)U/mL,是优化前的3.21倍。该酶的最适作用温度为50℃,最适pH为8.0,其水解普鲁兰糖的产物中有大量麦芽三糖和麦芽六糖,表明其为一种新颖的II型普鲁兰酶,在洗涤剂、高麦芽糖浆和麦芽六糖的生产中有着潜在的巨大利用价值。

A strain of Bacillus megaterium Y103 was screened from the corn stalk humus soil,and the fermentation conditions for pullulanase production by B.megaterium Y103 were optimized by single factor experiments and response surface methodology.The results showed that the optimized medium formula was waxy rice starch 8.5 g/L,yeast extract 13.3 g/L,peptone 26.7 g/L,KH2PO40.5 g/L,MgSO4·7H2O 0.1 g/L,MnSO4·7H2O 0.05 g/L,and NaCl 2.0 g/L.The optimal fermentation conditions were as follows:initial pH 8.8,temperature 21℃,and time 55 h.Under the optimal fermentation conditions,the pullulanase activity reached(0.77±0.03)U/ml,which was 3.21 times that of before optimization.The optimal reaction temperature and pH of the pullulanase was 50℃and 8.0,respectively.A large amount of maltotriose and maltohexaose were found in the products of pullulan hydrolysis,which indicated that pullulanase was a novel pullulanase type II with great potential utilization value in the production of detergents,high malt syrups and maltohexose.