Sensitivity of Pseudomonas stutzeri to EDTA: effects of growth parameters and test conditions

EDTA is highly toxic for Pseudomonas stutzeri. The bactericidal effect is not significantly attenuated by treatment of the cells at 0 degrees C rather than 25 degrees C, nor by osmotic stabilisation of the treated cells. The few surviving cells are not genetically resistant, but resistance to EDTA (and to some cationic antibiotics) can be induced by growing organisms in magnesium-limited media. Under these conditions, there is increased production of a protein of molecular mass about 20 kD. Comparable results have been reported for Pseudomonas aeruginosa. The mode of action of EDTA on these pseudomonads is discussed.