Immobilization of lipase enzyme extracted from thermophilic Bacillus licheniformis 14T local isolate

Abstract

Background: Currently, lipase enzymes are considered important bio-catalysts in many industries due to their unique properties in catalyzing various types of reactions in aqueous solutions. By targeting hydrocarbons in the oil, lipase enzymes contribute to the breakdown of hydrocarbons, reducing the environmental impact of oil spills and facilitating the remediation of contaminated areas.Methods: A thermostable lipase from local isolate Bacillus licheniformis 14T has been immobilized on four different supports that include the inactivated chitosan beads, activated chitosan beads with glutaraldehyde, inactivated chitosan-alginate beads, and activated chitosan-alginate beads with glutaraldehyde.Results The purified free lipase enzyme exhibited the highest enzymatic activity at 34.6 units/ml, surpassing all immobilized enzymes. Specific activity increased to 96.25 and 79.03 unit/mg protein for activated chitosan beads and activated chitosan-alginate beads, while decreasing to 52.95 and 46.05 unit/mg protein for inactivated chitosan beads and inactivated chitosan-alginate beads compared to the free enzyme. Optimal conditions for the immobilized enzyme differed, with the highest enzyme activity achieved after 60 minutes at 60°C and pH 8, reaching 48.6, 70.23, 43.12, and 61.2 units/ml on various supports, contrasting with the free enzyme's peak activity after 30 minutes at 50°C and pH 7.Conclusions: Immobilizing the lipase enzyme increases the specific activity of the immobilized enzyme on the supports of activated chitosan beads with, also the immobilization process led to a change in the optimal conditions for the activity of the immobilized enzyme compared with the optimal conditions of free enzyme.Keywords: Lipase; Bacillus licheniformis; Immobilization; Chitosan; Alginate