Enhanced Production,\nEnzymatic Activity, and Thermostability\nof an α‑Amylase from Bacillus amyloliquefaciens in Lactococcus lactis

A novel α-amylase gene (BAA) from Bacillus\namyloliquefaciens was cloned into Lactococcus\nlactis, designing two recombinant α-amylases\nto facilitate extracellular secretion. Following optimizing the expression\nconditions, the highest yield of BAA (88.12 mmol/L) was achieved upon\n36 h induction and 5 ng/mL nisin concentration. Determining the enzymatic\nproperties of BAA revealed its poor stability and activity at high\ntemperatures, hindering its widespread application. Therefore, we\nused computer-aided design to generate a mutant, S275L, which exhibited\nsignificantly improved activity and thermostability: an 18.7% increase\nin enzymatic activity (3767.38 U/mg), a 10 °C increase in optimal\ntemperature, and a 49.2% improvement in stability at 60 °C. Molecular\ndynamics simulations and force analysis confirmed these enhancements.\nFinally, the mutant S275L’s potential was further analyzed\nfor starch hydrolysis on poultry feed. Therefore, the mutant S275L\nholds promising as an enzyme agent for enhanced feed digestibility\nand quality.