PRODUCTION OF GALACTO-OLIGOSACCHARIDE FROM LACTOSE BY STERIGMATOMYCES-ELVIAE CBS8119

Our stock cultures were screened for microorganisms that can produce g alacto-oligosaccharide (Gal-OS) from lactose. Of the 574 strains of ba cteria and yeasts tested, Sterigmatomyces elviae CBS8119, Rhodotorula minuta IFO879, and Sirobasidium magnum CBS6803 were found to be effici ent producers of Gal-OS from lactose and S. elviae CBS8119 was selecte d as a representative, high-level producing strain, With toluene-treat ed resting S. elviae CBS8119 cells, 135 mg of Gal-OS per mi was produc ed from 360-mg/ml lactose, During this reaction, the by-product glucos e was found to inhibit Gal-OS production. Therefore, in order to remov e the glucose from the reaction mixture, a culture method in which cel l growth followed the enzymatic reaction was devised, which increased the yield of Gal-OS considerably because of the consumption of glucose for cell growth. Under such conditions, 232 mg of Gal-OS per mi was p roduced from 360-mg/ml lactose after incubation at 30 degrees C for 60 h. The structure of the major product was identified as O-beta-D-gala ctopyranosyl-(1-->4)-O- beta-D-galactopyranosyl-(1-->4)-D-glucopyranos e (4'-galactosyl-lactose) by C-13 nuclear magnetic resonance spectrosc opy.