以从自然界中筛选的野生芽孢杆菌XLG-1为出发菌株,通过紫外线诱变及紫外线-氯化锂复合诱变筛选出高产中温α-淀粉酶的优异菌株XLG-51,经鉴定为枯草芽孢杆菌(Bacillus subtilis)。初步研究了其所产的α-淀粉酶的酶学性质:通过SDS-starch-PAGE电泳与酶谱分析得该酶分子质量为60 ku左右,最适作用温度为60℃,最适作用pH范围为5.0～6.5,且在最适条件下具有较强的稳定性。以该菌株为生产菌进行5 L罐发酵实验,产酶达5298 U/mL。
A α-amylase producing strain was isolated and identified as Bacillus subtilis.After the treatments of UV and UV-LiCl,a high-producing α-amylase mutant(XLG-51) was obtained.Further study showed that the α-amylase produced by XLG-51 was fairly thermo stable and acid stable,and the optimum temperature and pH were 60℃ and 5.5 respectively.SDS-starch-PAGE electrophoresis and enzymography analysis revealed that the enzyme had a molecular weight of about 60 ku.Furthermore,the experiment was amplified on 5 L fermentor and the yield of enzyme activity was 5298 U/mL.
