Purification and Properties of an Esterase from Bacillus licheniformis and it’s Application in Synthesis of Octyl Acetate

Abstract

Background: Esterase plays a major role in the degradation of natural materials, industrial pollutants and also provides an immense contribution to the eco-friendly approaches in various industrial applications. Objective: In the present study, extracellular esterase from bacterial isolate Bacillus licheniformis was purified, characterized and used in the synthesis of octyl acetate. Methods: Purification of esterase from Bacillus licheniformis was achieved using Sephadex G-75 column chromatography. Gas chromatography was used to analyze the octyl acetate synthesis. Results: The enzyme was salted out using ammonium sulphate precipitation and 60-70% saturation gave maximum specific activity of the enzyme during precipitation. A purification fold of 6.46 and yield of 9.69% was achieved when esterase from Bacillus licheniformis was purified using Sephadex G-75 column chromatography. Native as well as SDS-PAGE analysis gave a single band of 42 kDa. This showed that the enzyme was purified to homogeneity and it was a monomer with molecular weight of 42 kDa. Biochemical characterization of the enzyme revealed that it had optimum temperature of 45°C in 0.1 M Tris-HCl buffer of pH 8.0. On optimizing different parameters, such as molar ratio of reactants, incubation time, temperature, and amount of protein, the % yield of octyl acetate was found to be 77.3%. Conclusion: In this work, simple method was used to purify esterase and the enzyme was further used in producing esters/products of commercial value within a reasonably short period of 12 h with a maximum yield of 77.3%.