Composition of chromosome fragments participating in phage P22-mediated transduction of Salmonella typhimurium

Abstract

It was demonstrated quantitatively that the chromosome fragments carried by phage P22 and concerned in abortive transduction of motC- H1- flaK region of Salmonella typhimurium are heterogeneous in genetic composition. When the total number of fragments carrying motC, flaK, or both was taken as 100, those carrying motC +, motC + H1, motC + H1 flaK +, H1 flaK +, and flaK + were approximately 2, 27, 0.2, 4, and 67%, respectively. These proportions indicate that the chromosome fragments having termini between H1 and flaK are 94% and those between H1 and motC are 6%. This result was obtained from the number of trails (motile heterogenotes) produced in the transduction from a motile donor strain in phase 1 ( gp) to three kinds of nonmotile mutants in expressed or latent phase 1 ( i) on NGA medium containing both anti- gp and anti- 1.2 sera or anti- 1.2 serum for the phase 2 flagellar antigen. The three nonmotile mutants, motC244, flaK48, and motC244 flaK48, have mutational sites cotransducible with H1, and presumably satisfy the working premise that the exogenotic H1 allele in motile heterogenotes is always expressed when present and motility of the heterogenotes is inhibited by the antiserum for the phase 1 flagellar antigen of the donor.