Intrinsic insensitivity to cadmium of the L-lactate oxidizing system in staphylococcoccus aureus

Starved cells of cadmium-sensitive Staphylococcus aureus 17810S accumulated 109Cd via the Mn2+ porter energized by the membrane potential (delta psi) generated by L-lactate oxidation. However, Cd2+ accumulation did not result in inhibition of respiration and consequent generation of electrochemical proton gradient (delta muH+) via the respiratory chain. Thus, delta muH(+)-consuming processes, such as ATP synthesis and [14C]glutamate transport proceeded normally, despite the presence of Cd2+ in the cytoplasm. The mechanism of the intrinsic cadmium-insensitivity of the L-lactate oxidizing system is discussed.