Immobilization of Candida rugosa Lipase on Magnetic Biosilica Particles: Hydrolysis and Transesterification Studies

Biodiesel is a renewable fuel used mainly in diesel engines. At the present time, biodiesel is largely produced by acid or alkali transesterification reactions. A hot spring water algae isolate "Kamptonema formosum" was cultivated at three different temperatures, and the algae oil was extracted using chloroform and methanol (v/v, 1/1 ratio) as the solvent. The maximum amount of algal biomass (1.86 g/L) was obtained at 25 degrees C, and the extracted oil was found to be 48.7% of the total dry biomass. Diatomic earth particles (Biosilica) were magnetized via thermal co-precipitation reaction, and then it was grafted with polydopamine (MBioSi@PDA). The lipase was covalently immobilized on the surface of the MBioSi@PDA via Schiff's base reaction. The immobilization conditions were optimized and 3.0 mg/mL as the initial lipase concentration in the immobilization medium was found to be the most favorable. At this lipase concentration, the amount of the immobilized lipase on the MBioSi@PDA particles and immobilization yield were found to be 81.9 mg/g and 67.9%, respectively. The MBioSi@PDA@lipase particles were used for conversion of K. formosum oil into biodiesel, and the conversion yield was found as 91.2% under optimum conditions. The fatty acid methyl ester (FAME) compositions of the alga oil were identified using a gas chromatography-mass spectrometry (GC-MS). K. formosum oil mainly composed of the required fatty acids (i.e., 16 and 18 carbon long-saturated and unsaturated fatty acids) for biodiesel synthesis, and these were advantageous for synthesis of biodiesel from the algal oil.