Effects of Salt Concentration on the Intracellular Cadmium Content of and the Cadmium Uptake by a Highly Cadmium-tolerant, Moderately HalophilicPseudomonassp.

Abstract

The intracellular cadmium (Cd) content was measured with early stationary phase cells of a highly Cd-tolerant moderately halophilic bacterium Pseudomonas sp. No. 40 cultivated in 1M and 3M NaCl medium containing 0 to 2500 μg of CdCl2/ml. It was found that the Cd contents were greatly affected by the NaCl concentration of the medium. When the bacterium was cultivated in the 1, 2, 3, and 4M NaCl medium containing 1500 μg of CdCl2/ml, the intracellular Cd content was 25.0, 4.1, 3.1, and 2.0 mg Cd per g of dry cells, respectively. The intracellular Cd content decreased with increases of NaCl concentration of the medium. The fact seems to reflect Cd-tolerance of the bacterium towards the growth in the medium of different NaCl concentration. It is worthwhile to note that the bacterium showed the highest Cd-tolerance (in 3M NaCl) and the lowest Cd content among the bacteria so far known. The bacterial cells grown in the 1M NaNO3 and 1M Na2SO4 medium accumulated 1.8–1.3 times as much Cd2+ as those in the 1M NaCl ...