Galacto-oligosaccharide production from lactose by Sirobasidium magnum CBS6803

N. ONISHI, I. KIRA AND K. YOKOZEKI. 1996. Galacto-oligosaccharide (Gal-OS) was produced from lactose by a yeast, Sirobasidium magnum CBS6803. With toluene-treated resting cells, 136 mg ml^?1 of Gal-OS was produced from 360 mg ml^?1 of lactose at 50°C for 42 h. Then, the yield of Gal-OS was increased by a culture method in which cell growth followed the enzymatic reaction : 224 mg ml^?1 of Gal-OS was produced at 30°C for 60 h. Finally, combination of the toluene-treated resting cells and glucose oxidase plus catalase was applied to improve productivity by the removal of a by-product, glucose, which inhibits the Gal-OS production, from the reaction mixture. In this case, 242 mg ml^?1 4-galactosyl-lactose. of Gal-OS was produced at 50°C for 42 h without cell growth. The structure of the major product ws identified as 4-galactosyl-laetos.