abstract |
PURPOSE:To produce galacto-oligosaccharide in high yield and selectivity, by culturing a microbial strain belonging to Cryptococcus genus, separating novel beta-galactosidase A from the cultured microbial cell and using the enzyme for the production of the saccharide. CONSTITUTION:A microbial strain belong to Cryptococcus genus and capable or producing novel beta-galactosidase A [e.g. Cryptococcus laurentii var laurentii OKN-4 (FERM P-7629)] is cultured in a conventional medium containing a carbon source, a nitrogen source, an inorganic salt, etc., at about 20-40 deg.C and about 2-9 pH. The carbon source contains lactose as a component. beta- Galactosidase produced in the microbial cell is separated by conventional separation and purification means. The enzyme has an optimum pH of 4-5 and an optimum temperature of 50-60 deg.C, is inhibited with mercury ion, glucose, etc., and has a molecular weight of about 200,000 measured by gel-filtration. |