Correlation of Pathogenicity and Calcium dependency of Yersinia pseudotuberculosis and Yersinia Enterocolitica with their plasmid content

Abstract

Derivatives of Yersinia pseudotuberculosis and Y. enteroco/itica were selected by surface plat-ing of the wild type strains on blood agar base containing MgClz and sodium oxalate (magnesium oxalate agar). Some of these derivatives lacked the 42 megadalton (Mdal) plasmid and possess the 36 Mdal plas-mid. whereas. others lacked both kinds of plasmid. Lack of calcium dependency for growth at 37*C and lack of pathogenicity of the derivatives were demonstrated aI1d indicated that the genetic information for calcium dependency and pathogenicity was carried on the 42 Mdal plasmid of the two species. Whereas, the role (roles) of 36 Mdal plasmid (if any) were not obvious.