title: Zinc Oxide Nanoparticles Supported Lipase Immobilization for Biotransformation in Organic Solvents: A Facile Synthesis of Geranyl Acetate, Effect of Operative Variables and Kinetic Study.
abstract: The present study describes grafting of zinc oxide (ZnO) nanoparticles with polyethyleneimine (PEI) followed by modification with glutraldehyde used as the bridge for binding the enzyme to support. The prepared nanocomposites were then characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy, utilized for synthesis of geranyl acetate in n-hexane. Among all the three prepared nanocomposites (ZnO + PEI, ZnO + PEI + SAA, ZnO + PEI + GLU), Candida rugosa lipase immobilized on ZnO-PEI-GLU was found to be best for higher ester synthesis. The operating conditions that maximized geranyl acetate resulted in the highest yield of 94 % in 6 h, molar ratio of 0.1:0.4 M (geraniol/vinyl acetate) in the presence of n-hexane as reaction medium. Various kinetic parameters such as V max, K i(G), K m(G), and K m(VA) were determined using nonlinear regression analysis for order bi-bi mechanism. The kinetic study showed that reaction followed order bi-bi mechanism with inhibition by geraniol. Activation energy (E a ) was found to be lower for immobilized lipase (12.31 kJ mol(-1)) than crude lipase (19.04 kJ mol(-1)) indicating better catalytic efficiency of immobilized lipase. Immobilized biocatalyst demonstrated 2.23-fold increased catalytic activity than crude lipase and recycled 20 times. The studies revealed in this work showed a promising perspective of using low-cost nanobiocatalysts to overcome the well-known drawbacks of the chemical-catalyzed route.
authors.affiliation: Environmental Genomics and Proteomics Lab, BRD School of Biosciences, Sardar Patel Maidan, Satellite campus, Sardar Patel University, Sardar Patel Maidan, P.O. Box # 39, Vallabh Vidyanagar, Anand, 388 120, Gujarat, India.
authors.forename: Vrutika
authors.initials: V
authors.lastname: Patel
authors.affiliation: Environmental Genomics and Proteomics Lab, BRD School of Biosciences, Sardar Patel Maidan, Satellite campus, Sardar Patel University, Sardar Patel Maidan, P.O. Box # 39, Vallabh Vidyanagar, Anand, 388 120, Gujarat, India.
authors.forename: Chandani
authors.initials: C
authors.lastname: Shah
authors.affiliation: Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Anand, 388 120, Gujarat, India.
authors.forename: Milind
authors.initials: M
authors.lastname: Deshpande
authors.affiliation: Environmental Genomics and Proteomics Lab, BRD School of Biosciences, Sardar Patel Maidan, Satellite campus, Sardar Patel University, Sardar Patel Maidan, P.O. Box # 39, Vallabh Vidyanagar, Anand, 388 120, Gujarat, India. datta_madamwar@yahoo.com.
authors.forename: Datta
authors.initials: D
authors.lastname: Madamwar
mesh_terms: D000085:Acetates / Q000138:chemical synthesis* / Q000737:chemistry; D000080462:Acyclic Monoterpenes; D001711:Biotransformation; D002175:Candida / Q000201:enzymology; D002384:Catalysis; D004798:Enzymes / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000737:chemistry*; D007700:Kinetics; D008049:Lipase / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013729:Terpenes / Q000138:chemical synthesis* / Q000737:chemistry; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D000085:Acetates; D000080462:Acyclic Monoterpenes; D004798:Enzymes; D004800:Enzymes, Immobilized; D012997:Solvents; D013729:Terpenes; C432872:geranyl acetate; D008049:Lipase; D015034:Zinc Oxide
keywords: Biosynthesis; Geranyl acetate; Immobilization; Lipase; Polyethyleneimine