Elution of loosely bound acid phosphatase from Staphylococcus aureus.

Strains of Staphylococcus aureus from the International-Blair and the Seto-Wilson series of phage propagating strains were examined for acid phosphatase activity. This enzyme was found to occur in varying amounts in three different fractions: free (6 to 60%), loosely bound (25 to 82%), and firmly bound (0 to 46%). Propagating strain 3A, because of its high activity, was chosen for further study. The rate of enzyme production paralleled cell growth in Trypticase Soy Broth, but followed a biphasic pattern in a semisynthetic casein acid-hydrolysate medium with glyceryl phosphate. Maximal elution of acid phosphatase in the loosely bound fraction, presumably from the surface of cells, occurred in the alkaline pH range. From log-phase cells, elution was maximally effected with buffered 1.0 M KCl (pH 7.5), but stationary-phase cells required twice the concentration of KCl.