Bio-ceramic, mesoporous cuttlebone of Sepia officinalis is an ideal support for the immobilization of Bacillus subtilis AKL13 lipase: optimization, adsorption, thermodynamic and reaction kinetic studies

Abstract

Mesoporous cuttlebone powder of Sepia officinalis (CBP) was characterized and used as matrix for the immobilization of Bacillus subtilis AKL 13 lipase (BsL). Particle size and surface area of the matrix used for enzyme immobilization were 89.95 µm and 1.631 m2 g−1, respectively. Remarkable thermostability (54% of weight loss at 700 °C) of CBP was determined in TGA profile. The lipase immobilization process parameters were sequentially optimized by response surface methodology followed by artificial neural network and genetic algorithm. The maximum lipase loading capacity of CBP was 255 mg g−1 of support. Immobilized lipase (CBP-BsL) showed maximum specific activity of 5808 U mg−1 of protein in p-nitrophenol palmitate hydrolysis. Adsorption isotherm study revealed that the binding of lipase on the surface of CBP was Langmuir and the binding was physical adsorption. CBP-BsL showed lower activation energy (51.4 KJ mol−1) and higher thermal stability with half-lives of 13.3 h at 50 °C. Higher activity retention in nonpolar solvents and 69% of operational stability after 15 cycle of reaction were measured.