Anaerobic 109Cd accumulation by cadmium-resistant and -sensitive Staphylococcus aureus |
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Authors: | Zofia Tynecka Teresa Skwarek Anna Malm |
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Institution: | Department of Pharmaceutical Microbiology, Medical Academy, Lublin, Poland. |
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Abstract: | Washed cells of the cadmium-sensitive Staphylococcus aureus 17810S accumulated 109Cd under anaerobic conditions via the Mn2+ porter down delta psi in 1 or 100 mM phosphate buffer, pH 7; in washed cells of the cadmium-resistant S. aureus 17810R 109Cd accumulation was highly reduced. Nigericin did not stimulate anaerobic Cd2+ accumulation by strain 17810R in 100 mM phosphate buffer, suggesting that delta psi could energize Cd2+ efflux. In 1 mM phosphate buffer nigericin restored Cd2+ accumulation via the Mn2+ porter down delta psi in strain 17810R, indicating involvement of delta pH in Cd2+ extrusion. Increase of phosphate buffer concentration from 1 to 100 mM and addition of energy source at steady-state caused delta psi-dependent Cd2+ efflux from the nigericin-pretreated cells of strain 17810R. This suggests that the Cd2+ efflux system in S. aureus may require energy of both ATP and delta mu H+. |
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Keywords: | Staphylococcus aureus Cadmium accumulation Cadmium efflux Membrane potential pH gradient |
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