Detergent-compatible Lipase from Aspergillus niger: Statistical Optimization, Purification, Characterization, and...

In the present study, RSM was used to optimize production parameters, yielding optimal conditions of pH 7, inoculum volume of 4.5 mL, incubation time of 96 h, and temperature of 50 °C, resulting in maximum enzyme production and the highest enzyme activity of 17.3 U/mL. Optimization increased the enzyme yield 1.8-fold compared to the unoptimized con-ditions. The quadratic model was significant (p = 0.04) and had an adequate precision of 6.82 and an R2 of 0.7684. External validation runs confirmed model reliability (observed activity of 16.9 ± 0.6 U/mL, a 2.3 % deviation from the predicted value). Lipase was purified using ammonium sulfate precipitation, dialysis, ion-exchange chromatography, and gel filtration chromatography, yielding a 4.07-fold purification with 45.90 % recovery. Biochemical characterization of the purified lipase revealed a Km of 2.14 mM and a Vmax of 204 U/mL, indicating moderate substrate affinity and effective catalysis. The low Km supports activity at low substrate concentrations typical of wash conditions, and high Vmax enables rapid stain removal. The purified lipase improved de-tergent performance, as demonstrated by a stain-removal test, in which the enzyme-containing detergent removed stains more effectively than the non-enzyme detergent. Heat-inactivated lipase controls confirmed that stain removal was enzymatic. In the visual representation, percent stain removal from cotton cloth showed that the lipase-containing detergent removed stains more ef-fectively than locally available ones. This study demonstrated the production of fungal lipases, highlighting their potential as promising candidates for detergent applications, pending further industrial-scale validation.