Eliminatory action of glycine on drug resistance of Escherichia coli K12 harboring an R factor.

Glycine, known to inhibit the synthesis of a peptidoglycan component of the bacterial cell wall, was effective in eliminating drug resistance of Escherichia coli K12 JE2100 strain harboring the R100–1 factor, although in lower frequencies than that of sodium dodecyl sulfate (SDS). The action of glycine was found to be less effective on the same R factor in JE177 strain, and not effective on the F factor in W6. Infection of R factors from R+ cells to R– cells was found to take place in the glycine broth as efficiently as in broth without glycine. This might result in lowering the apparent efficiency of the action of glycine on those plasmids. The segregation patterns of drug-susceptible clones obtained by the glycine treatment were different from those obtained after the SDS treatment. These results coupled with other evidences suggest that the mode of action of glycine on R+ cells may be different from those of other curing agents and may involve mechanisms other than selection of R– or drug-susceptible segregants that are present in R+ culture.