产β-半乳糖苷酶芽孢杆菌的筛选及产酶条件的优化

Screening of Bacillus Producing β-galactosidase and Optimization of Its Enzyme Production Conditions

[目的]筛选产β-半乳糖苷酶的芽孢杆菌并对其产酶条件进行优化。[方法]从土壤中筛选出一株具有β-半乳糖苷酶活性的菌株,对其进行鉴定并对其发酵产酶条件进行优化。[结果]该菌株被初步鉴定为巨大芽孢杆菌。该菌株的最佳碳源是乳糖,最佳氮源是牛肉膏和蛋白胨,Na+对产酶有明显的促进作用。当乳糖含量为1.20%,牛肉膏含量为0.63%,蛋白胨含量为1.04%时,该菌株所产β-半乳糖苷酶酶活可达3.68 U/ml。初始pH值为8.0,培养温度为45℃,接种量为2%,振荡培养17 h,该菌株所产β-半乳糖苷酶的酶活最高,为5.49 U/ml。[结论]该菌株在高温条件下生长旺盛,适宜生长pH值范围广,在生产实践中具有一定的应用价值。

[Objective] The aim was to screen the bacillus producing β-galactosidase and optimize its conditions for enzyme production.[Method] A strain with β-galactosidase activity was screened from the soil.The strain was identified and its conditions for enzyme production was optimized.[Result] The strain was identified preliminarily as Bacillus megaterium.The optimum carbon source of the strain was lactose and optimum nitrogen sources were beef extract and peptone.Na＋ had obvious promotion for its enzyme production.When the lactose content was 1.20% and beef extract content was 0.63% and when the peptone content was 1.04%,the enzyme activity of the strain producing β-galactosidase could be reached to 3.68 U/ml.When the initial pH value was 8.0,the culture temperature was 45 ℃,the inoculation amount was 2% and the shaking culture time was 17 h,the activity of β-galactosidase produced by the strain was highest,being 5.49 U/ml.[Conclusion] The strain grew vigorous under the high temperature and its pH range suitable for growing was wide,which had certain application value in practice.