Optimization of microbial thermostable lipase production from mesophilic bacteria Serratia marcescens scl1

A thermostable lipase-producing bacterium, Serratia marcescens scl1, previously isolated from medicinal industrial effluent in West Bengal, India, was employed for the optimization of thermostable lipase production under controlled laboratory conditions. The study systematically evaluated the influence of physicochemical and nutritional parameters on enzyme yield. Optimal lipase production was achieved at 35°C and pH 7.0 using 1.0% olive oil as a lipidic carbon source, 1.0% starch as a non-lipidic carbon source, and 1.0% yeast extract as an organic nitrogen source. Among inorganic nitrogen sources, 1.0% lysine and 1.0% ammonium nitrate were found to significantly enhance enzyme synthesis. Process optimization further revealed that maximum thermostable lipase activity was obtained at an agitation speed of 150 rpm, an incubation period of 24 hours, and an inoculum concentration of 4.0%. The supernatant collected after centrifugation at 8000 rpm for 8 minutes exhibited the highest extracellular enzyme activity. Metal ion supplementation with MgCl₂ and surfactant addition of Tween 80 further stimulated lipase production. The optimized conditions substantially improved thermostable lipase yield from S. marcescens scl1, highlighting its potential as a robust biocatalyst for industrial applications in biotransformation, detergent formulation, and biodiesel synthesis.