BIOCATALYTIC APPROACH FOR THE PRODUCTION OF VALUE-ADDED COMPOUNDS AND COFACTOR REGENERATION USING THE MEMBRANE REACTOR

摘要

The possibilities of developing biobased products as well as viable and biorefinary applications havebeen expanding. S. cerevisiae may be used as a raw material for enzyme production. Using the latter biomassfeedstock, alcohol dehydrogenase (ADH) among other enzymes may be obtained. This work focused on thestereoselective reduction of ketones to form chiral alcohols using ADH, a NAD(H)-dependent oxidoreductase. Therequired coenzymes were regenerated during the catalysis. Evaluations were made in a discontinuous process: thekinetic constants for ADH in reference to acetophenone (K_M=1.04 mM and V_(MAX)= 1.47 U) and 2-hexanone(K_M=1.38 mM and V_(MAX)= 1.05×10~(-1) U); the effect of the temperature on the enzyme′s activity was also evaluatedwithin the range from 25°C up to 50°C. The continuous bioconversion consisted of either oxidative or reductivereaction under the following condition: phosphate buffer (10 mM; pH 7.0 or 6.0), 1-phenylethanol or 2-hexanol (10mM) and acetophenone or 2-hexanone (10 mM); β-NAD or β-NADH (1mM) and ADH (150 U). The reactor was fedcontinuously under a specific feeding rate of 2 mL.h~(-1). The average of the formation of 1-phenylethanol was 3.1 mMwhereas for 2-hexanol, it was 3.6 mM. ADH responded accordingly to a substrate-coupled procedure using themembrane reactor.