Drug resistance of enteric bacteria. VI. Introduction of bacteriophage P1CM into Salmonella typhi and formation of PldCM and F-CM elements.

Kondo, Eiko (Gunma University, Maebashi, Japan), and Susumu Mitsuhashi. Drug resistance of enteric bacteria. VI. Introduction of bacteriophage P1CM into Salmonella typhi and formation of P1dCM and F-CM elements. J. Bacteriol. 91:1787-1794. 1966.-Bacteriophage P1CM was introduced into Salmonella typhi by means of both phage infection and conjugation with Escherichia coli F(+) lysogenic for the phage. Upon incubation with a P1CM phage lysate, S. typhi and S. abony yield CM(r) cells which are lysogenic for P1CM, but S. typhimurium LT2 does not. The P1CM phage is adsorbed slightly to S. typhi, but no infectious centers are formed when the phage is plated on this strain. Tests on P1CM-adsorbing capacity of the S. typhi P1CM(+) strain and on plaque formation and transduction ability of the recovered phage from this strain indicated that the cell and the phage population did not have any special advantage over the original cell and phage population. Conjugation of S. typhi with E. coli F(+) carrying P1CM(+) gave three types of S. typhi CM(r) clones: those which carry the whole P1CM phage, those with the P1dCM element, and those with nontransferable CM(r). The second type has the F factor and is sensitive to f phages in spite of its typical behavior, serologically and biochemically, as S. typhi. It can donate the P1dCM and F(+) characters to E. coli F(-) or F(-)/P1 strains. As a consequence of conjugation with the E. coli F(+) strain, the CM(r) character of the third type of S. typhi, the nontransferable CM(r) element, acquired conjugational transferability, owing to the formation of the element, F-CM. This element can be transferred to an E. coli F(-) strain at a very high frequency (ca. 10(0)). Both the F and CM(r) determinants are jointly transduced with P1 phage and are jointly eliminated by acridine dye treatment.