Fig 6.

Frequency of horizontal DNA transfer in cell-to-cell mating. (A) Horizontal DNA transfer into H. pylori wild-type strain 26695 and 26695-REd in mating with H. pylori strains with different methylation activities. H. pylori wild-type strain 26695 or 26695-REd with double genetic markers (Cm^r Str^r) as recipients were mated with H. pylori strains 26695, J99, JP26, or J166, each containing a single genetic marker (Km^r) in the vacA locus, as donors. The numbers of transformants positive for all three phenotypes (Km^r, Cm^r, and Str^r) were determined, and the frequency of horizontal DNA transfer to the H. pylori wild-type and the REd strain was determined. (B) Horizontal DNA transfer from H. pylori wild-type strain 26695 and 26695-REd in mating with H. pylori strains. H. pylori wild-type strain 26695 or 26695-REd with a single genetic marker (Cm^r) in the ureAB locus as donors were mated with H. pylori strains 26695, J99, JP26, or J166, each containing double genetic markers (Km^r Str^r) as recipients. The numbers of transformants positive for all three phenotypes (Km^r, Cm^r, and Str^r) were determined, and the frequency of horizontal DNA transfer from the H. pylori wild type and the REd mutant to each recipient strain was determined.