β-D-Galactosidase and phospho-β-D-galactosidase in staphylococci:distribution and inducer specificity

Abstract

Thirty-three strains of 9 Staphylococcus species were examined for the existence of β-D-galactosidase (βG) and phospho-β-D-galactosidase (PβG) . All these strains were positive in lactose fermentation (Lac^+) . PβG activity was detected in strains of S. aureus, S. epidermidis, S. haemolyticus, S. Ientus and S. hominis, while p G was found in strains of S. saprophyticus, S. capitis, S. simulans and S. intermedius. Lactose-negative (Lac^-) mutants defective in these activities could be isolated with several representative strains. PβG synthesis in S. aureus and S. epidermidis was induced by lactose, galactose and galactose-6-phosphate, while that in S. Ientus was induced by lactose and galactose. Synthesis of βG was induced by lactose and methyl-β-D-thiogalactoside in S. saprophyticus, but only by lactose in S. simulans and S. intermedius.