title: Rhizopus oryzae lipase immobilized on hierarchical mesoporous silica supports for transesterification of rice bran oil.
abstract: The tunable textural properties of self-oriented mesoporous silica were investigated for their suitability as enzyme immobilization matrices to support transesterification of rice bran oil. Different morphologies of mesoporous silica (rod-like, rice-like, and spherical) were synthesized and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption-desorption isotherms. The surface area, pore size, and ordered arrangement of the pores were found to influence the immobilization and activity of the enzyme in the mesopores. The immobilization in rod-like silica was highest with an immobilization efficiency of 63 % and exhibited minimal activity loss after immobilization. Functionalization of the mesoporous surface with ethyl groups further enhanced the enzyme immobilization. The free enzyme lost most of its activity at 50 °C while the immobilized enzyme showed activity even up to 60 °C. Transesterified product yield of nearly 82 % was obtained for 24 h of reaction with enzyme immobilized on ethyl-functionalized SBA-15 at an oil:methanol ratio of 1:3. Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectrometry (GC-MS) were used to characterize the transesterified product obtained. The reusability of the immobilized enzyme was studied for 3 cycles.
authors.affiliation: Centre for Nanotechnology and Advanced Biomaterials, School of Chemical and Biotechnology, SASTRA University, Thanjavur, 613401, India.
authors.forename: Prashanth
authors.initials: P
authors.lastname: Ramachandran
authors.forename: Guru Krupa
authors.initials: GK
authors.lastname: Narayanan
authors.forename: Sakthivel
authors.initials: S
authors.lastname: Gandhi
authors.forename: Swaminathan
authors.initials: S
authors.lastname: Sethuraman
authors.forename: Uma Maheswari
authors.initials: UM
authors.lastname: Krishnan
mesh_terms: D000327:Adsorption; D001709:Biotechnology; D004800:Enzymes, Immobilized / Q000737:chemistry; D004951:Esterification; D005656:Fungal Proteins / Q000737:chemistry*; D008049:Lipase / Q000737:chemistry*; D010938:Plant Oils / Q000737:chemistry*; D016062:Porosity; D012233:Rhizopus / Q000737:chemistry / Q000201:enzymology*; D000073879:Rice Bran Oil; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D010938:Plant Oils; D012822:Silicon Dioxide; D008049:Lipase; D000073879:Rice Bran Oil