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

Abstract

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 1 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 1 in the aqueous-organic twophase system could be reused, and NAD 1 cycling numbers of 3040 were obtained after repeated operation for 40 h.

Experimental and Theoretical Analysis of Phase Equilibria in a Two-phase System Used for Biocatalytic Esterifications

“…1 Á/3. The first conclusion, which can be derived from the experimental results, is that the partitioning behavior of the two polar reactants cannot be described by constant partition coefficients as is commonly done in the field of biocatalysis in aqueous Á/organic two-phase systems (Antczak et al ., 2001;Dias et al ., 1991;Ferreira-Dias and da Fonseca, 1995;Frense et al, 1996;Monot et al ., 1991;Mustranta et al ., 1993;Suye et al ., 2002;Wehtje and Adlercreutz, 1997;Wu et al, 2002;Yang and Robb, 1994). Compared to the literature, low concentration levels were used in our experiments.…”

“…In the field of biocatalysis with aqueous Á/organic two-phase systems, constant partition coefficients, representing the ratio of the reactant concentration in the organic phase to that in the aqueous phase, are most frequently employed to characterize the partitioning behavior of reactants (Antczak et al ., 2001;Dias et al ., 1991;Ferreira-Dias and da Fonseca, 1995;Frense et al ., 1996;Monot et al ., 1991;Mustranta et al ., 1993;Suye et al ., 2002;Wehtje and Adlercreutz, 1997;Wu et al ., 2002;Yang and Robb, 1994). However, Eggers et al (1989) stated that only in very dilute systems can partition coefficients be assumed to be constant while in non-ideal solutions the partition coefficients are a function of concentration.…”

ADH-catalysed hexanol oxidation with fully integrated NADH regeneration performed in microreactors connected in series

“…Acetaldehyde was used as a substrate for the coenzyme regeneration because of its low price and high specicity of the ADH towards it. [23][24][25] Three different microreactor systems for the biocatalytic hexanol oxidation with simultaneous coenzyme regeneration (namely, single microreactor chip, two microreactor chips connected in series, and three microreactor chips connected in series) were investigated and compared.…”

ADH based NAD+ regeneration in a microreactor

“…Enzyme alcohol dehydrogenase (ADH) isolated from baker's yeast was used while the same enzyme was employed as the biocatalyst in the hexanal production process . Acetaldehyde was used as a substrate for coenzyme regeneration because of its low price and the high specificity of ADH towards it . Disadvantages of the selected reaction system are the possibility of enzyme deactivation both by substrate, acetaldehyde, and the product, ethanol, instability (possibility of self‐condensation in the solution) and volatility of acetaldehyde .…”