Two strains, Saccharomyces cerevisiae and Bacillus mucilaginosus, are investigated in their abilities to endure heavy metal ions in this study. Meanwhile, the biosorption capacities of Cd2+ and Zn2+ by Saccharomyces cerevisiae and Bacillus mucilaginosus have been researched through altering the cultivating and biosorption conditions. Besides, the two microorganisms have been adapted in Cd2+and Zn2+mediums as to improve their biosorption capa(:ities.'fhe result indicates that the highest tolerant concentrations of Saccharomyces cerevisiae to Cd2 and Zn2+ are 50-60mg·L-1 and 300mg·L-1 or so respectively; While the highest tolerant concentrations of Bacillus mucilaginosus to Cd2 and Zn2+ are about 100mg·L-1 and 100-110mg-L"1 respectively.The biosorption capacities of the two microorganisms have been tested by changing adsorption time, initial pH, cell dosage and the initial Cd2 and Zn2+ concentrations. The result indicates that under the adsorption conditions of Cd2+ and Zn2+ 5mmol·L-1,14.98g dry cell·L-1 and 19.97gdry cell·L-1, the adsorption rates of Cd2 and Zn2+ by Saccharomyces cerevisiae are 93.15% and 84.00% respectively; While under the adsorption conditions of Cd2+ and Zn2+ 5mmol·L-1,40.0g dry cell·L-1 and 29.8g dry cell·L-1, the adsorption rates of Cd2 and Zn2+by Bacillus mucilaginosus are 87.45% and 97.50% respectively.After seven and nine generations'metal ion adaptations to Saccharomyces cerevisiae, the tolerance to Cd2+ and Zn2+.can be obviously improved and its biosorption capacity of Cd2+ can be improved as well; While After eight and nine generations'metal ion adaptations to Bacillus mucilaginosus, its biosorption capacity of Cd2+and Zn2+can both be improved.
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