Production of a surface active bacterial lipase using spent cooking oil for waste valorization

Abstract Anthropogenic pollution and the necessity for sustainable waste valorization strategies. Synthetic detergents are widely used, but they can also cause environmental pollution and ecological impacts. Detergent formulations containing enzymes can reduce the need for potentially hazardous chemical additives. Microbial green lipases are an environmentally friendly option for detergent applications. Spent cooking oil is a potential low-cost substrate for the production of lipases. Among 34 native bacterial isolates recovered from an oil-contaminated environment, Klebsiella sp. EGHK-10 was selected based on its higher lipase activity. Submerged fermentation at 30 °C for 24 h with 1% spent cooking oil as substrate supplemented with 0.1% tryptone and Tween 80 resulted in maximum lipase production (11.746 U/mL/min). The concentrated crude lipase exhibited surface-active properties, as demonstrated by an oil displacement diameter of 66.7 mm. Following concentration, the enzyme preparation showed a final recovery of 11.592%. Maximum enzyme activity was observed at 40 °C and pH 8.0 and was enhanced in the presence of Fe²⁺, Ba²⁺, and sodium dodecyl sulfate (SDS). The enzyme showed partial inhibition in the presence of oxidizing agents. The estimated Km and Vmax values were 2.396 mM and 104.167 µmol/min, respectively, while the activation energy was 23.694 kJ/mol. The concentrated crude lipase enhanced the removal of used car oil stains from fabric when combined with Pril detergent. This study demonstrates the potential for valorizing spent cooking oil as a low-cost substrate for the production of a bacterial lipase with promising surface-active and detergent-related properties. The concentrated crude lipase was compatible with Pril detergent and enhanced qualitative oil-stain removal, supporting its potential as a sustainable enzyme additive for detergent-related applications. Further quantitative cleaning studies under practical washing conditions are required to validate its applicability in commercial detergent formulations.