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 - H 1- 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 + H 1, motC + H 1 flaK + , H 1 flaK + , and flaK + were approximately 2, 27, 0.2, 4, and 67%, respectively. These proportions indicate that the chromosome fragments having termini between H 1 and flaK are 94% and those between H 1 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, motC 244, flaK 48, and motC 244 flaK 48, have mutational sites cotransducible with H 1, and presumably satisfy the working premise that the exogenotic H 1 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.