GALACTO-OLIGOSACCHARIDE PRODUCTION USING A RECYCLING CELL-CULTURE OF STERIGMATOMYCES-ELVIAE CBS8119

Addition of small amounts of Fe2+, Zn2+, Cu2+ and thiamine-HCl to the culture medium was required for promoting the galacto-oligosaccharide (Gal-OS)-producing activity of Strerigmatomyces elviae CBS8119, when t he concentration of yeast extract in the medium was lowered to 0.1 g l (-1). Galacto-oligosaccharide production using a recycling cell cultur e was performed in a medium containing 360 mg ml(-1) of lactose supple mented with optimal concentrations of Fe2+ (1.5 mg l(-1) oT FeSO4 . 7H (2)O), Zn2+ (15 mg l(-1) of ZnSO4 ..7H(2)O), Cu2+ (0.5 mg l(-1) of CuS O4 . 5H(2)O) and thiamine-HCl (1 mg l(-1)). Galacto-oligosaccharide pr oduction was maintained at high levels during six cycles of production , with the amount of Gal-OS produced in each cycle being more than 216 mg ml(-1) (weight yield of more than 60%).