A new Klebsiella planticola strain (Cd-1) grows anaerobically at high cadmium concentrations and precipitates cadmium sulfide

Heavy metal resistance by bacteria is a topic of much importance to the bio remediation of contaminated soils and sediments. We report here the isolati on of a highly cadmium-resistant Klebsiella planticola strain, Cd-1, from r educing salt marsh sediments. The strain grows in up to 15 mM CdCl2 under a wide range of NaCl concentrations and at acidic or neutral pH. In growth m edium amended with thiosulfate, it precipitated significant amounts of cadm ium sulfide (CdS), as confirmed by x-absorption spectroscopy. In comparison with various other strains tested, Cd-1 is superior for precipitating CdS in cultures containing thiosulfate. Thus, our results suggest that Cd-1 is a good candidate for the accelerated bioremediation of systems contaminated by high levels of cadmium.