IS NATURAL GENETIC-TRANSFORMATION A MECHANISM OF HORIZONTAL GENE-TRANSFER IN YERSINIA

We investigated the capacity of different Yersinia strains with emphas is to Yersinia enterocolitica to take up and incorporate DNA. by natur al genetic transformation. Our studies were initiated by the observati on of partial homology between the virulence plasmid of a pathogenic I : enterocolitica strain (O: 3, biovar 4) and plasmids indiginous to di fferent apathogenic Y. enterocolitica biovar 1A strains revealed by hy bridization studies. Furthermore, an observation of natural genetic tr ansformation in a strain of Y. enterocolitica has been published by CA LLAHAN and KOROMA (1979). To detect an uptake and incorporation of DNA , we incubated potential recipient strains with naked DNA under varyin g experimental conditions. The parameters tested were - the recipient strain, - the markers used to detect a DNA transfer, - the condition o f the transforming DNA, - the nutrient availability, the temperature, - the growth phase, and - the influence of stress. In our experiments, we could not identify conditions under which Y. enterocolitica could be naturally transformed. We thus conclude that natural transformation is unlikely to be an important mechanism for horizontal gene transfer in Yersinia.