Magnetic lipase B from <i>Candida antarctica</i> (CALB) biocatalyst for integrated valorization of tilapia by‐products and biodiesel biorefining

Abstract The immobilization of lipase B from Candida antarctica (CALB) on an amino‐epoxy functionalized magnetic support (Fe 3 O 4 ‐PEI‐DGEBA) resulted in a highly stable and efficient biocatalyst for biofuel production from tilapia oil. The synthesized support was characterized using scanning electron microscopy, transmission electron microscopy, X‐ray fluorescence spectroscopy, Fourier transform infrared (FTIR), thermogravimetric analysis, and vibrating sample magnetometry, confirming the successful immobilization and preservation of the magnetic core. The immobilized CALB exhibited superior catalytic performance, achieving a 97% immobilization yield, remarkable thermal and pH stability, and retaining over 80% activity after 120 days of storage. Additionally, it maintained high esterification efficiency over 10 reuse cycles, demonstrating its industrial applicability. Molecular docking and molecular dynamics simulations revealed that immobilization enhanced CALB's substrate selectivity, favoring long‐chain saturated fatty acids through hydrophobic interactions with residues such as Leu140, Ala141, and Val154. Hybrid molecular mechanics and quantum mechanics simulations identified the nucleophilic attack step as the rate‐limiting stage of the esterification process, with an energy barrier of 17.5 kcal mol −1 , aligning with the enzyme's optimized catalytic efficiency post‐immobilization. The biodiesel produced 98.8% conversion efficiency, with key FTIR and nuclear magnetic resonance signals confirming successful esterification. However, its viscosity exceeded ASTM and ANP standards, suggesting the need for blending with lower‐viscosity biofuels. These findings highlight Fe 3 O 4 ‐PEI‐DGEBA@CALB as a promising biocatalyst for sustainable biofuel production, combining high stability, reusability, and efficiency, with potential applications in green chemistry and industrial biocatalysis.