Arsenic and cadmium resistance in environmental isolates of Yersinia enterocolitica and Yersinia intermedia

Environmental strains of Yersinia enterocolitica representing biotype 1A la ck virulence plasmid (pYV) and are regarded as non-pathogenic. Though these occupy a diverse range of environmental niches, nothing is known about the ir resistance to heavy metals. The minimal inhibitory concentrations (MICs) of various metal ions, namely Ag+, Cu2+, Zn2+, Cd2+, As5+, and As3+, for s trains of Yersinia enterocolitica (biotype 1A) and Yersinia intermedia (bio types 1, 2, and 4), isolated from sewage effluents or pork, were determined . All isolates were resistant (MICs 2.5-5 mM) to Cd2+. The MICs of arsenic varied with bacterial strain and the chemical species of the arsenic used. For the majority of the strains, however, it was between 5-10 mM of Na2HAsO 4. 7H(2)O and NaAsO2, and 0.625-2.5 mM of As2O3. Except for one isolate, MI Cs of Ag+, Cu2+, and Zn2+ for these strains were in the range of 0.3-0.625 mM.