转氨酶产生菌的筛选鉴定及其摇瓶发酵条件的优化

Screening, Identification and Fermentation Optimization of Aminotransferase-producing Strain

摘要:

从土壤中分离到1株具有支链氨基酸转氨酶活性, 且亮氨酸转氨酶活性较高的菌株WJ44。通过观察形态特征、生理生化实验以及16S rRNA序列的比对和系统发育分析, 鉴定其为蜡状芽孢杆菌(Bacillus cereus)。经过对产酶条件的优化, 确定最佳摇瓶产酶条件为：葡萄糖20 g/L, 蛋白胨15 g/L, 牛肉膏5 g/L, 玉米浆15 g/L, KH2PO4 3 g/L, MgSO4·7H2O 0.5 g/L, 初始pH 7.0, 培养温度37℃, 装液量20 mL/250 mL三角瓶, 摇床转速200 r/min。WJ44菌株在最佳产酶条件下培养10 h其亮氨酸转氨酶酶活即可达到45.787 U/mL, 菌体干重8.643 g/L, 分别比原来提高了54%与10%, 是一株产酶和生长性能较佳的菌株。

Abstract:

A strain named as WJ44 with capability of producing branched-chain aminotransferase was isolated from the soil, the enzyme activity is especially high when used leucine as a substrate. According to the physiological characteristics, biochemical characteristics and 16S rRNA sequence of WJ44, the strain was identified as Bacillus cereus. The optimal carbon source and nitrogen source were also determined as 20 g/L glucose, 15 g/L tryptone and 5 g/L beef extract, respectively. The optimal proportion of other component in the medium is corn steep liquor 15 g/L, KH2PO4 3 g/L, MgSO4·7H2O 0.5 g/L. The optimum original pH value is 7.0, the cultural temperature is 37℃,