Study On Immobilization Of Candida SP.99-125Lipase Upon Hydrophobic Matrix

Due to the special characteristics of lipases, the synthetic utility and stability of lipases can be greatly improved when lipase is immobilized upon hydrophobic matrix. In this paper, different hydrophobic matrixes were employed to immobilized lipase from Candida sp.99-125obtained in our lab.Candida lipase was immobilized by physical adsorption onto different macroporous adsorption styrene resins. Immobilization effect and catalytic ability of lipase adsorbed on different resins were studied. A98.9%degree of immobilization was achieved when the adsorption procedure was performed in the presence of heptane. The lipolytic activity, esterification activity and the activity recovery of lipase adsorbed on resin in heptane was4.07,2.23and3.43times higher than that of lipase adsorbed in sodium phosphate buffer, respectively. Effect of immobilization conditions on esterification activity and thermal stability was investigated using weakly polar resin AB-8as carrier. The catalytic properties of immobilized lipase in the production of biodiesel in low aqueous media were studied while using non polar resin NKA as carrier. As lipase was adsorbed on NKA in heptane to produce biodiesel, the batch conversion rate reached97.3%. After19consecutive batches, the conversion rate remained70.2%.Hydrophilic cotton membrane was successfully reacted with different functional reagents in order to get hydrophobic cotton membrane. Relative lipolytic activity and relative esterification activity of lipase adsorbed on diverse hydrophobic cotton were researched. When lipase adsorbed on hydrophobic cotton reacted by octylbromide and1-hexadecanol, the relative esterification activity of lipase was1.25and1.32higher than that of lipase immobilized on hydrophilic cotton, respectively. In synthesis of biodiesel from soybean oil using broth adsorbed on hydrophobic cotton reacted by octylbromide,1-octylalcohol,1-decanao, and l-hexadecanol,better conversion rate of biodiesel within five batches was got.Candida sp.99-125lipase was entrapped in organic-inorganic sol-gel powder prepared by polymerization of tetramethoxysilane(TMOS) and propyltrimethoxysilane(PTMS). PEG(MW=20000) and HC1were used as additive and catalyst during the sol-gel process, respectively. The optimal preparation conditions were studied, which were PTMS/TMOS molar ratio=4:1, R value (water/silane molar ratio)=20, enzyme loading=3.71%(w/w) of silane precursor,1-1.5mg PEG/mg lipase and hydrolysis time of silane precursor=35min. The specific activity of immobilized lipase was2.02times higher than that of non-immobilized lipase under the optimal water content in esterification reaction system. The esterification activity of immobilized lipase retained59.1%of the initial activity after2h incubation under100℃, and the activity of immobilized lipase remained almost unchanged after8consecutive batches of each12h reaction.