Isolation and characterization of Lysobacter Enzymogene PS15 for Protease Production: Optimization Using Response Surface Methodology

In this study, a novel protease-producing strain, Lysobacter enzymogenes PS15, was successfully isolated from soil and identified through biochemical characterization and 16S rRNA gene sequencing. A sequential optimization strategy was employed to enhance protease yield. The one-factor-at-a-time (OFAT) method first determined an effective nutrient composition of 1.5% dextrose, 1.25% peptone, and 0.6% NaCl, and served as a screening tool to determine the suitable operational ranges for pH (6-8), temperature (34-46 °C), incubation time (12-60 h), and inoculum volume (0.25-3.25 %). These ranges were subsequently optimized using response surface methodology (RSM) using a central composite rotatable design (CCRD). The model predicted a maximum protease activity of 36.62 U mL ^-1 , which was experimentally confirmed at 35.09 U mL ^-1 under the optimal conditions (pH 7.0, 39 °C, 47 hours, and 2.3% inoculum volume). The crude enzyme exhibited optimal performance at 40 °C and pH 8, maintaining stability up to 45 °C. This work represents the first RSM-based optimization of protease production from L. enzymogenes , establishing its strong potential for diverse applications, including proteinaceous waste degradation and biocatalysis.