Acriflavine as an Effective Agent for eliminating F-factor in Escherichia coli K-12

Abstract

THE artificial elimination of F-factor in Escherichia coli K-12 was obtained by treating F+ cells in a cobalt- or nickel-containing medium¹. Of the two methods described in that communication, the direct method was difficult to apply to some strains derived from K-12, because the facility of conversion of F+ cells to F− cells varied with the strains used. On the other hand, the resistant-isolation method consistently gave F− cells, but was somewhat tedious, because the development of resistance to cobalt or nickel was very slow. Recently, however, it has been found that acrinavine is more effective for converting F+ cells into F− than cobalt or nickel and other metals (Ikoma, I., unpublished work).