Selection oflonmutants inEscherichia coliby treatment with phenothiazines

Abstract

SUMMARYGrowth ofE. coliK12 in the presence of chlorpromazine or promethazine resulted in the appearance of a special kind of mutational change with a frequency of 5–10%. These cells were UV-sensitive and very mucoid in their colony formation. The strains were characterized as colanic acid producing on the basis of phage m-59 sensitivity and we tentatively conclude that these mutants are Lon−.In another series of experiments drug treatment ofE. colifailed to yield significant numbers of auxotrophs and the back mutation rate of a number ofS. typhimuriumHis−strains was not significantly increased.