Directional Mining and Thermostability Modification of Novel Acid-Resistant Maltogenic Amylase from Lactobacillus paralimentarius

Due to the low pH and high temperature in dough rising and baking processes of starchy foods, high thermostability and acidic resistance have become the most important characteristics for commercial maltogenic amylase as a baking antiaging additive. Therefore, a novel maltogenic amylase from Lactobacillus paralimentarius, exhibiting an activity of 274.79 U·mg–1 under optimal conditions at 50 °C and pH 5.0, was screened through EnzymeMiner-assisted preliminary screening, microbial sources-assisted reselection, and structure analysis-assisted final selection, which was based on the bioinformatics. Data-driven rational design was carried out to construct a mutation library for the improvement of thermostability; the optimal reaction temperature and activity of mutant A375P/S257P were increased to 65 °C and 430.15 U·mg–1, respectively, while the half-life at 60 °C increased by 7.09-fold. The structural analysis indicated that the formation of new hydrogen bonds and the increase in rigidity reduce the free energy of mutant A375P/S257P, thereby further enhancing its thermostability.