[The colicin selection of the S forms of representatives in the Enterobacteriaceae family]

A method based on a lower sensitivity of S forms to colicines, in comparison with R forms, was used for the selection of S forms of bacteria from dissociated cultures of E. coli O.124:K72, S. sonnei, and S. flexneri. The cultures are inoculated in nutrient agar from the external segment of the zone of bacterial growth suppression by colicines D, E1, and V+m, where the content of S forms is relatively higher at the expense of death of R forms. The content of S forms in the resultant cultures of different strains was 1.7 to 31.1 times higher that in the initial cultures.