CW2M3分泌新型淀粉酶的最适条件及酶的应用条件

从原筛选的产酶菌株CW₂出发， 经多次紫外诱变、 初筛和复筛后， 获得了变异菌株CW₂M₃， 其产酶水平为原菌株的332.7％， 且具有良好的遗传稳定性. 薄层层析证明，CW₂M₃分泌的新型淀粉酶能有效地催化淀粉降解产生异麦芽低聚糖， 产物主要包括异麦芽糖、 潘糖、 异麦芽三糖等. 用正交法结合薄层层析法确定了各因素对CW₂M₃产酶水平的影响， 结果表明， 培养温度是显著因素，CW₂M₃的最适产酶条件为： 用牛肉膏培养基（牛肉膏0.7%、 蛋白胨0.7%、 NaCl 0.5%、 pH 7.0）培养， 温度40 ℃， 时间12　h. 用该酶催化淀粉转化为异麦芽低聚糖时， 酶促反应时间和温度均是显著影响因素， 酶催化淀粉降解的最适条件为: 温度65 ℃， 酶促反应1.0　h， 体系pH为7.0.

Opimization Conditions to Secrete and Utilize Neoamylase from CW2M3

Strain CW₂M₃ was mutagenised from strain bacillus thermolicheniformis CW₂ by ultraviolet ray, and the activity of secreted neoamylase by CW₂M₃ is increased by 232.7% compared with that of CW₂ under the identical conditions. Moreover, strain CW₂M₃ is genetically stabile. The results of thin layer chromatography of the products from starch catalyzed by the neoamylase demonstrate that the neoamylase can be used to catalyze starch to produce isomaltooligosaccharide, including isomaltose, panose, isomaltotriose, from starch. The optimum conditions under which the neoamylase was secreted by CW₂M₃ were confirmed by orthogonal tests. The results show that the most important parameter to secrete the neoamylase is temperature for culturingCW₂M₃ and the optimum conditions to secrete the neoamylase are as follows. The strain CW₂M₃ should be cultured in the medium of 0.7% brewis, 0.7% peptone, 0.5% NaCl, pH 7.0 at 40 ℃ for 12 h, whereas the most important parameter to utilize the neoamylase is catalytic duration and the optimum conditions to utilize the neoamylase are in pH 7.0 starch system, at 65 ℃ for 1.0 h. 