Efficient Repeated Use of Alcohol Dehydrogenase with NAD + Regeneration in an Aqueous-organic Two-phase System

Bioconversion of cinnamyl alcohol to cinnamaldehyde was carried out in an aqueous-organic two-phase reaction system by the repeated use of horse liver alcohol dehydrogenase (HLADH) and NAD + with coenzyme regeneration. Both HLADH and the coenzyme were efficiently entrapped in the aqueous phase, while the substrate was supplied successively from the organic phase and the product was accumulated in the organic phase. Optimum conditions for cinnamaldehyde production in the aqueous-organic two-phase system were also examined, including substrate concentration, pH, and organic solvent type. Under suitable conditions, both HLADH and NAD + in the aqueous-organic two-phase system could be reused, and NAD + cycling numbers of 3040 were obtained after repeated operation for 40 u h.