Biosynthesis of diisooctyl 2,5‐furandicarboxylate by Candida antarctica lipase B (CALB) immobilized on a macroporous epoxy resin

Abstract

Diisooctyl 2,5‐furandicarboxylate (DEF), an ester derivative of 2,5‐furandicarboxylic acid (FDCA, a bio‐based platform chemical), resembles the physical and chemical properties of phthalates. Due to its excellent biodegradability, DEF is considered a safer alternative to the hazardous phthalate plasticizers. Although FDCA esters are currently mainly produced by chemical synthesis, the enzymatic synthesis of DEF is a green, promising alternative. The current study investigated the biosynthesis of DEF by Candida antarctica lipase B (CALB) immobilized on macroporous resins. Out of five macroporous resins (NKA‐9, LX‐1000EP, LX‐1000HA, XAD‐7HP, and XAD‐8) evaluated, the LX‐1000EP epoxy resin was identified as the best carrier for CALB, and the XAD‐7HP weakly polar resin was identified as the second best. The optimal immobilization conditions were as follows: CALB (500 μL) and LX‐1000EP (0.1 g) were incubated in phosphate butter (20 mM, pH 6.0) for 10 h at 35°C. The resulting immobilized CALB (EP‐CALB) showed an activity of 639 U/g in the hydrolysis of p‐nitrophenyl acetate, with an immobilization efficiency of 87.8% and an activity recovery rate of 56.4%. Using 0.02 g EP‐CALB as the catalyst in 10 mL toluene, and the molar ratio of 2,5‐dimethyl furanediformate (1 mmol/mL) and isooctyl alcohol (4 mmol/mL) that was 1:4, a DEF conversion rate of 91.3% was achieved after a 24‐h incubation at 50°C. EP‐CALB had similar thermal stability and organic solvent tolerance compared to Novozym 435, and both were superior to CALB immobilized on the XAD‐7HP resin. EP‐CALB also exhibited excellent operational stability, with a conversion rate of 52.6% after 10 repeated uses. EP‐CALB could be a promising alternative to Novozym 435 in the biomanufacturing of green and safe plasticizers such as DEF.