Cultural Conditions of Heavy Metal-ion Tolerant Microorganism and Accumulation of Heavy Metal-ion into the Cells.

The cultural conditions and the intra cellular accumulation of cadmium was studied using a cadmium tolerant yeast strain B-7 which had been isolated from activated sludge collected from a zinc mining area. The organism was able to grow in a medium containing 3,000 / of cadmium-ion. (C ) Optimum conditions for the growth of the organisms were 20~22 and pH 5.0~8.0 under aerobic condition. The maximum cadmium accumulation was observed when the organism was grown at pH 6.0. The growth of B-7 was not affected by the addition of a silicone-based antifoamer, which stimulated the intra cellular accumulation of cadmium. The intra cellular cadmium accumulation started after the cell ceased to grow. One gram of cells accumulated 34.17mg of cadmium when the organism was grown in a medium containing 500 / of cadmium and 0.2%, v/v silicone-based antifoamer at 28 for 48 hours with shaking. About 73 % of the accumulated heavy metal by the organism was found in the cytoplasm.m.