Carboxymethylcellulose and poly(vinyl alcohol) used as a film support for lipases immobilization
Lipases from 10 different sources were immobilized on poly(vinyl alcohol) (PVA), carboxymethycellulose (CMC) and poly(vinyl alcohol):carboxymethycellulose blend (50:50% m/m) and used as biocatalysts in esterification reactions of carboxylic acids with n-pentanol in organic media. Among the tested lipases, higher yields in n-pentyl laurate were obtained when lipases from Mucor javanicus (MJL) or Rhyzopus oryzae (ROL) were immobilized in CMC, PVA and CMC:PVA blend (70–99%). ROL was selected in the following experiments. The influence of ROL loading in the supports showed that 50 mg lipase/0.5 g support is sufficient to obtain the ester in quantitative yield (99%). The effect of temperature (25–50 °C) was also evaluated, and the highest yields (99%) were obtained after ROL was immobilized in the above supports. Lower yields were obtained using the enzyme in a free form (6–33%) regardless of the temperature. The influence of organic solvent was also considered for this reaction using ROL/free, ROL/PVA and ROL/CMC systems. Higher yields (99%) were obtained when non-polar solvents were used. ROL supported in PVA, CMC and CMC:PVA blend could be reused, at least, 10 times during an 80-day period, keeping its enzyme activity and macroscopic properties (yields in the range of 77–99%). Using ROL in a free form, ROL lost its activity completely after six reactional cycles. The influence of acyl donor was also studied using an ROL/PVA system and n-hexane as an organic solvent. A dependence on carbon number of the alkyl chain was observed. Higher yields (99%) were observed for fatty acids with more than 10 carbon atoms. These results showed that polymers such as PVA, CMC and CMC:PVA blends can be used successfully as alternative materials for lipase immobilization.
Journal: Process Biochemistry - Volume 40, Issue 8, July 2005, Pages 2677–2682