Synthesis of geranyl acetate in non-aqueous media using immobilized Pseudomonas cepacia lipase on biodegradable polymer film: Kinetic modelling and chain length effect study

Pseudomonas cepacia lipase (PCL) was immobilized on ternary blend biodegradable polymer made up of polylactic acid (PLA), chitosan (CH), and polyvinyl alcohol (PVA). Immobilized biocatalyst was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), % water content, protein and lipase activity assay. The lipase activity assay showed enhanced activity of immobilized lipase than crude lipase. Higher half life time (t1/2) and lower deactivation rate constant (Kd) was found for the n-hexane among various tested solvent. Influence of various reaction parameters on enzyme activity were studied in detail. When geraniol (1 mmol) and vinyl acetate (4 mmol) in toluene (3 mL) were reacted with 50 mg immobilized lipase at 55 °C; then 99% geraniol was converted to geranyl acetate after 3 h. Various kinetic parameters such as rmax, Ki(A), Km(A), Km(B) were determined using non-linear regression analysis for ternary-complex and Bi-Bi ping-pong mechanism. The kinetic study showed that reaction followed ternary-complex mechanism with inhibition by geraniol. Activation energy (Ea) was found to be lower for immobilized lipase (13.76 kCal/mol) than crude lipase (19.9 kCal/mol) indicating better catalytic efficiency of immobilized lipase. Immobilized biocatalyst demonstrated 4 fold increased catalytic activity than crude lipase and recycled five times.