Microsome-bound alcohol oxidase catalyzed production of carbonyl compounds from alcohol substrates

High yield conversion of a wide range of alcohol substrates to their corresponding aldehydes was demonstrated using a microsomal alcohol oxidase (AOx) from Aspergillus terreus. The microsome bound AOx preparation was then immobilized into polyurethane foam matrix following a simple adsorption technique. The successful immobilization of the enzyme into the foam matrix was demonstrated microscopically and by biological staining. The enzyme loading was measured as ∼2.02 U mg−1 (76.6 mg protein %) of polyurethane foam. The optimum activity of the immobilized enzyme was detected in the pH range 7.0–8.0. The catalytic activity of the immobilized AOx was utilized for the production of n-heptanal. A maximum n-heptanal yield of 20.7 ± 1.2% (w/w) was achieved at a substrate concentration of 10 mM n-heptanol; beyond this concentration substrate dependent inhibition of the catalytic reaction was observed. The operational stability of the immobilized enzyme was determined and found to be ∼60% of the initial activity till the fifth reaction cycle, thus providing high cumulative yield of the product. The deactivation (kd) and half-life time (t1/2) of the immobilized enzyme were 5.17 × 10−5 min−1 and ∼9 days, respectively. The results demonstrated the potential application of the polyurethane foam immobilized microsomal AOx-based environmentally benign biocatalytic process for the production of industrially important n-heptanal.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► High yield production of carbonyl compounds using microsome-bound AOx catalyses was established. ► The AOx catalyzed production of carbonyls was achieved in environmentally benign conditions. ► The microsome bound AOx was successfully immobilized in polyurethane foam matrix. ► The synthesis of industrially important n-heptanal was achieved by polyurethane foam immobilized AOx catalytic process. ► High operational stability of the immobilized enzyme was demonstrated.