Recombinant Expression and Bioprocess Optimization of Priestia megaterium α-Amylase and Its Impact on Dough...

α-Amylase is a key hydrolytic enzyme in starch degradation, playing a crucial role in industrial bioprocesses such as dough fermentation. However, optimizing α-amylase production remains challenging due to variations in microbial sources, culture conditions, and induction strategies. In this study, Priestia megaterium α-amylase (PmAmy) production was optimized for the first time based on the biomass/IPTG ratio in a controlled bioprocess. The impact of enzyme supplementation with equal quantity and enzymatic activity on dough fermentation was also evaluated to ensure consistent performance and effective application. Under the bioprocess conditions of 1.0 vvm airflow, 37°C, and 1000 rpm, a biomass-to-IPTG ratio was optimized as 20 g_biomass mmol_IPTG ^-1 at pH 7.0. Fed-batch fermentation was conducted at a specific growth rate of µ = 0.22 h^-1 for 22 h, yielding an α-amylase activity of 67.7 ± 4.0 U mL^-1 at a cell concentration of 22.3 ± 5.3 g L^-1 Dough fermentation trials demonstrated 99% efficiency compared to commercial α-amylase, despite PmAmy being in its primary recovery form. These findings highlight its potential for industrial baking applications. This study offers a scalable and sustainable enzyme production strategy, contributing to improved fermentation efficiency, product quality, and economic feasibility in food biotechnology.