beta-D-galactosidase activity in streptococci of serological group B.

Group B streptococci isolated from humans differed significantly in beta-D-galactosidase-activity from those of bovine mastitis. This could be demonstrated in a relatively simple and rapid test using a fluorogenic 4-methylumbelliferyl-beta-D-galactoside conjugate. Only 10 (12%) of 82 group B streptococcal cultures from human produced beta-D-galactosidase. On the other hand, 74 (96%) of 77 "bovine" cultures formed this enzyme. Thus, beta-D-galactosidase activity could be used as an additional marker for the differentiation between group B streptococci of human and bovine origin.