Abstract: | For the first time Y. intermedia strains containing plasmids with a molecular weight of 82 MD have been detected in natural populations of urease-positive Yersinia. Such populations have been isolated from two species of birds and from the soil in the area where they have been killed (the Maritime Territory), as well as from washings from the surface of onions in a vegetable store (Chita Province). The strains, administered orally to white mice, proved to be nonpathogenic. Plasmids with a molecular weight of 82 MD are supposed to occur in natural populations of other Yersinia species. |