The biosorption characteristic of Pt(Ⅳ) onto Providencia vermicola and Shewanella oneidensisMR-1 was reported. Firstly, the effects of p H and ionic strength on the adsorption by two microorganisms were studied. It was found that the adsorption capacity was highest at pH 2.0 and the adsorption capacities were 58.62 and 72.20 mg/g, respectively. With the increase of ionic strength, the adsorption in Providencia vermicola enlarged but declined in Shewanella oneidensis. In the binary solution of Pt(Ⅳ) and Pd(Ⅱ...