Bacillus flexus β-淀粉酶低pH值突变体的构建及在麦芽糖制备中的应用  

Construction of Lower Optimum pH Mutants of Bacillus flexus β-Amylase and Its Application in Maltose Production

作　　者：亓旭辉 吴敬[1,2] 王蕾[1,2] 陈晟[1,2] QI Xuhui;WU Jing;WANG Lei;CHEN Sheng(State Key Laboratory of Food Science and Technology,Jiangnan University,Wuxi 214122,China;Key Laboratory of Industrial Biotechnology,Ministry of Education,Jiangnan University,Wuxi 214122,China)

机构地区：[1]食品科学与技术国家重点实验室,江南大学,江苏无锡214122 [2]江南大学工业生物技术教育部重点实验室,江苏无锡214122

出　　处：《食品与生物技术学报》2019年第10期105-110,共6页Journal of Food Science and Biotechnology

基　　金：国家杰出青年科学基金项目(31425020);江苏省产学研前瞻性联合研究项目(BY2015019-32);江苏高校优秀科技创新团队项目(2015);111计划(111-2-06)

摘　　要：工业上将β-淀粉酶与其他淀粉水解酶进行复配可获得高纯度的麦芽糖浆。相对于目前常用的植物来源β-淀粉酶,微生物β-淀粉酶具有生产工艺简单、不受原料限制、质量稳定、纯度高等优势,但其最适作用pH多为6.0~8.0,难以与其他淀粉水解酶(pH多为4.5~5.5)进行复配。本实验室前期获得的弯曲芽孢杆菌β-淀粉酶其最适pH值为7.0,本研究在此β-淀粉酶基础上构建T47K,Y164K,L396K三个突变体,其最适pH由突变前的7.0分别下降为6.0,4.5,5.5,其中L396K的最适温度也由突变前的50℃提高为60℃。以马铃薯淀粉(10%w/v)为底物进一步对L396K制备麦芽糖的转化条件进行探索与优化。结果表明,在反应初始pH为5.5,温度60℃,β-淀粉酶加酶量为100 U/g干淀粉时麦芽糖最大转化率达到80.2%,符合高纯度麦芽糖浆的生产要求。Beta-amylase and other starch hydrolases were complexed to produce high purity maltose syrup in industry.Compared with plantβ-amylase,the microbialβ-amylase has the advantages of high purity,little limitation with the raw materials,and the suitability for large-scale production.However,the optimum pH of the microbialβ-amylase is 6.0~8.0,which is difficult to complex with other starch hydrolases.In the pvious study,the optimum pH of Bacillus flexusβ-amylase was 7.0.In the present study,three B.flexusβ-amylse mutants T47K,Y164K,L396K were constructed and the optimal pH were changed from 7.0 to 6.0,4.5 and 5.5 respectively.At the same time,the optimum temperature of L396K was increased from 50℃to 60℃.The production conditions of maltose using L396Kβ-amylase was also optimized.When using potato starch(10%w/v)as the substrate under the condition of pH 5.5 and temperature 60℃,the yield of maltose reached 80.2%,which satisfied the production requirement of high purity maltose syrup.

关 键 词：Β-淀粉酶 定点突变 麦芽糖 弯曲芽孢杆菌 酶转化 

分 类 号：Q814.9[生物学—生物工程]