Effect of Ethylenediaminetetraacetic Acid (EDTA) and Metal Ions on Growth of Staphylococcus aureus 196E in Culture Media

ABSTRACT The effects of ethylenediaminetetraacetic acid (EDTA) and its salts, alone or in combination with Mg 2+ , Fe 3+ , Zn 2+ or Ca 2+ , on growth of S. aureus strain 196E, were studied. EDTA or its Na + or K + salts (0.8–1.7 mM), but not its Ca 2+ or Fe 3+ salts, inhibited cell growth in Brain Heart Infusion broth. Bacteriostatic effects in Casamino Acids‐Yeast Extract (CasY) broth were produced by 0.17 mM EDTA. Addition of Fe 3+ , Zn 2+ , or Ca 2+ to EDTA‐containing broth eliminated inhibition at an EDTA: cation molar ratio of 1:1, while Mg 2+ required a sevenfold concentration. Data suggest that EDTA exerts its inhibitory effect by chelating calcium and/or other essential cations which form complexes with comparable stability constants with EDTA.