Biosynthesis of L-ascorbic acid (vitamin C) by Saccharomyces cerevisiae

Saccharomyces cerevisiae cells incubated with D-glucose (D-Glc), D-galactos e or D-mannose (D-Man) synthesised D-erythroascorbic acid (D-EAA) but not L -ascorbic acid (L-AA). Accumulation of D-EAA was observed in cells incubate d with D-arabinose (D-Ara) whilst accumulation of L-AA occurred in cells in cubated with L-galactose (L-Gal), L-galaclono-1,4-lactone and L-gulono-1,4- lactone. When S. cerevisiae cells were incubated with D-[U-C-14]Glc, D-[U-C -14]Man or L-[1-C-14]Gal, incorporation of radioactivity into L-AA was obse rved only with L-[l-C-14]Gal. Pre-incubation of yeast cells with D-Ara subs tantially reduced the incorporation of L-[l-C-14]Gal into L-AA. Our results indicate that, under appropriate conditions, yeast cells can synthesise L- AA via the pathway naturally used for D-EAA biosynthesis. (C) 2000 Federati on of European Microbiological Societies. Published by Elsevier Science B.V . All rights reserved.