Hs. Shin et Pl. Rogers, KINETIC EVALUATION OF BIOTRANSFORMATION OF BENZALDEHYDE TO L-PHENYLACETYLCARBINOL BY IMMOBILIZED PYRUVATE DECARBOXYLASE FROM CANDIDA-UTILIS, Biotechnology and bioengineering, 49(4), 1996, pp. 429-436
Biotransformation of benzaldehyde to L-phenylacetylcarbinol (L-PAC) as
a key intermediate for L-ephedrine has been evaluated using immobiliz
ed pyruvate decarboxylase (PDC) from Candida utilis. PDC immobilized i
n spherical polyacrylamide beads was found to have a longer half-life
compared with free enzyme. In a batch process, the immobilized PDC gen
erally produced lower L-PAC than free enzyme at the same concentration
s of substrates due to increased by-products acetaldehyde and acetoin
and reduced benzaldehyde uptake. With immobilized PDC, L-PAC formation
occurred at higher benzaldehyde concentrations (up to 300 mM) with th
e highest L-PAC concentration being 181 mM(27.1 g/L). For a continuous
process, when 50 mM benzaldehyde and 100 mM sodium pyruvate were fed
into a packed-bed reactor at 4 degrees C and pH 6.5, a productivity of
3.7 mM/h (0.56 g/L . h) L-PAC was obtained at an average concentratio
n of 30 mM (4.5 g/L). The half-life of immobilized PDC reactor was 32
days. (C) 1996 John Wiley & Sons, Inc.