SCREENING AND FERMENTATION OF ENDO-ALPHA-N-ACETYLGALACTOSAMINIDASE-S,A MUCIN-HYDROLYZING ENZYME FROM STREPTOMYCES ACTING ON THE GALNAC-O-SER (THR) LINKAGE

Soil microorganisms were examined for their ability to grow on porcine gastric mucin as a sole source of carbon and energy. Streptomyces sp. OH-11242 thus selected was found to produce endo-alpha-N-acetylgalact osaminidase (endo-GalNAc-ase S), together with several mucin-degrading glycosidases. Endo-GalNAc-ase S is a new enzyme capable of hydrolyzin g the innermost GalNAc-O-Ser (Thr) linkage of the mucin molecule. Stud ies on the fermentation conditions necessary for its production reveal ed that the enzyme was induced by mucin but the induction was inhibite d by glucose and other easily assimilable carbon sources, as well as b y complex nitrogen sources. Addition of palmitate, lambda-carrageenan, or crude mucin to a mucin-based production medium enhanced enzyme pro duction and mycelial growth. When the initial mucin concentration of t he production medium was increased, the maximum titer of endo-GalNAc-a se S produced in the culture both also increased, while the cultivatio n time giving the peak enzyme titer was prolonged. As a result of the studies, increased and reproducible production of endo-GalNAc-ase S wa s achieved, reaching 42 units/ml in a 100-ml culture and 31 units/ml i n an 800-ml culture with 2 and 1.5% purified mucin, respectively, as t he major carbon source.