A new Rhizomucor miehei lipase immobilized on anhydride-hydrophobized amino supports: Optimization, characterization and application in preparing medium- and long-chain structured lipids

Medium- and long-chain triglycerides (MLCT) are a novel type of functional lipids that exhibit higher bioavailability when long-chain polyunsaturated fatty acids are esterified at the sn-2 position of the glycerol backbone. Enzyme-catalyzed synthesis of MLCT offers significant advantages, including environmental benignity, exceptional catalytic efficiency, and negligible by-product formation. Nevertheless, the inherent limitations of free enzymes in terms of recyclability and industrial implementation, remain a challenge. In this study, the hydrophobicity of the amino resin support LX-1000HAA (HAA) was modified via grafting with dodecenyl succinic anhydride (DDSA). The lipase RM was then immobilized onto the HAA-DDSA carrier via physical adsorption. The activity of the resulting immobilized lipase HAA-DDSA-RM was 1.74 times that of Lipozyme RM C and 2.13 times that of HAA-RM. Analysis of the adsorption kinetics and isotherms for lipase adsorption onto HAA-DDSA revealed that the adsorption behavior conformed to both the pseudo-second-order kinetic model and the Freundlich isotherm model. HAA-DDSA-RM was then employed in the preparation of MLCT in the reaction system comprising algal oil and capric acid. The DHA content at the sn-2 position reached 73.40% in the final product. Moreover, HAA-DDSA-RM demonstrated outstanding thermal stability, good storage stability, and superior recyclability, with 96% of its initial activity after 10 successive operational cycles. This study may provide a new approach for environmentally sustainable production of functional lipids by developing a robust immobilized lipase system.