Enzymatic transesterification of soybean oil with ethanol using lipases immobilized on highly crystalline PVA microspheres

• Published in: Biomass & bioenergy 2013-12, Vol.59, p.218-233
• Main Authors: Bergamasco, Juliana, de Araujo, Marcelo V., de Vasconcellos, Adriano, Luizon Filho, Roberto A., Hatanaka, Rafael R., Giotto, Marcus V., Aranda, Donato A.G., Nery, José G.
• Format: Article
• Language: English
• Subjects: amino acids; biocatalysts; Bioconversions. Hemisynthesis; bioenergy; Biological and medical sciences; Biomass; Biotechnology; crystal structure; enzyme activity; Enzyme immobilization; esters; ethanol; Fatty acid ethyl esters (FAEE); fatty acids; Fundamental and applied biological sciences. Psychology; hydrogen bonding; immobilized enzymes; Methods. Procedures. Technologies; Poly(vinyl) alcohol; Polymeric support; polyvinyl alcohol; Rhizomucor miehei; soybean oil; spectroscopy; synergism; transesterification; triacylglycerol lipase
• ISSN: 0961-9534; 1873-2909
• DOI: 10.1016/j.biombioe.2013.09.006

Polyvinyl alcohol (PVA) microspheres with different degree of crystallinity were used as solid supports for Rhizomucor miehei lipase immobilization, and the enzyme-PVA complexes were used as biocatalysts for the transesterification of soybean oil to fatty acid ethyl esters (FAEE). The amounts of immobilized enzyme on the polymeric supports were similar for both the amorphous microspheres (PVA4) and the high crystalline microspheres (PVA25). However, the enzymatic activity of the immobilized enzymes was depended on the crystallinity degree of the PVA microspheres: enzymes immobilized on the PVA4 microspheres have shown low enzymatic activity (6.13 U mg−1), in comparison with enzymes immobilized on the high crystalline PVA25 microspheres (149.15 U mg−1). A synergistic effect was observed for the enzyme-PVA25 complex during the transesterification reaction of soybean oil to FAEE: transesterification reactions with free enzyme with the equivalent amount of enzyme that were immobilized onto the PVA25 microspheres (5.4 U) have yielded only 20% of FAEE, reactions with the pure highly crystalline microsphere PVA25 have not yielded FAEE, however reactions with the enzyme-PVA25 complexes have yielded 66.3% of FAEE. This synergistic effect of an immobilized enzyme on a polymeric support has not been observed before for transesterification reaction of triacylglycerides into FAEE. Based on ATR-FTIR, 23Na- and 13C-NMR-MAS spectroscopic data and the interaction of the polymeric network intermolecular hydrogen bonds with the lipases residual amino acids a possible explanation for this synergistic effect is provided. [Display omitted] •Rhizomucor miehei lipase was immobilized on PVA microspheres (PVA4, PVA12, PVA25).•Polymer-enzyme complex was characterized by XDR, SEM, ATR-FTIR, 13C-CPMAS-NMR, 23Na-MAS-NMR.•Polymer-enzymes (PVA12 and PVA25) enzymes yielded considerable amount of ethyl esters.•Synergistic effect was observed for the polymer-enzyme complexes with high crystallinity (PVA25).