Effect of pH and inorganic salts on penicillinase formation in Staphylococcus aureus.

Leitner, Felix (Michael Reese Hospital, Chicago, Ill.) and Sidney Cohen. Effect of pH and inorganic salts on penicillinase formation in Staphylococcus aureus. J. Bacteriol. 83:314-323. 1962.-Staphylococcus aureus strain 55-C-1 exhibited a progressive increase in penicillinase activity as the pH of its growth medium dropped from 6.0 to 4.7. At pH 4.7, the increase in enzymic activity was inhibited markedly by Ca(++), somewhat less by Mg(++), and moderately by NaCl, KCl, and NH(4)Cl. Inhibition by NaH(2)PO(4) was greater than by NaCl. Growth at the same pH, in small concentrations of Fe(NH(4))(2)(SO(4))(2) (10(-5) to 10(-6)m), elevated penicillinase activity strikingly, an effect shared to a lesser degree with FeCl(3), CoCl(2), and, very slightly, MnCl(2). The available evidence indicated that the changes in enzymic activity were the result of changes in rate of formation of the enzyme.