产α-淀粉酶菌株的分离、鉴定及酶学性质研究

Screening,Identification and Characterization of An α-amylase-Producing Bacillus subtilis XL-15

目的:筛选高产α-淀粉酶菌株,为工业生产α-淀粉酶提供储备菌株。方法:利用碘液显色法和摇瓶发酵法,从土壤中筛选产α-淀粉酶菌株;通过菌落形态、菌体特征观察和16S rDNA序列比对对菌种进行鉴定;发酵粗酶液经硫酸铵沉淀、透析脱盐后,对其酶学性质进行初步研究。结果:从土壤中筛选到一株高产α-淀粉酶菌株,枯草芽孢杆菌Bacillus subtilis XL-15。该菌株所产α-淀粉酶的最适反应温度为50℃,最适作用pH为6.5;Ca2+和Mn2+对酶有激活作用,而Cu2+、Zn2+和EDTA对酶有抑制作用;酶的动力学研究测出米氏常数Km值为1.726mg/mL。结论:该菌株是产α-淀粉酶的较好材料,且具有一定的应用前景。

Objective： Screening of α-amylase-producing strain was undertaken to provide new strains for the produce of α-amylase in industry.Methods： α-amylase-producing strains were isolated from soil samples by initial screening with iodine solution and the flasks fermentation.Then strains were identified based on partial 16S rDNA gene sequence aligned with the GenBank database and its morphological characteristics.The properties of α-amylase of the strain were examined after ammonium sulfate fraction and dialysis for desaltion.Results：An α-amylase-producing strain was isolated and identified as Bacillus subtilis- 15. The results showed that the optimum temperature and pH of the enzyme were 50℃ and 6.5 respectively, the enzyme activity was obviously inhibited by Cu^2＋ , Zn^2＋ and EDTA. While stimulated by Ca^2＋ and Mn^2＋ , its Km was 1.726mg/mL. Conclusion： This study provided a good experimental material for the further studies on α - amylase.