Phenotypic (Phenomic) Lag in Bacteria

Abstract

A strain of Escherichia coli was exposed to ultra-violet light and then subjected to penicillin in minimal medium either directly, after washing, or after incubation in nutrient broth followed by washing. Auxotrophic mutants were recovered in all instances with frequencies increasing in the order of treatments listed. The relation of these findings, and of related observations reported in the literature, is discussed in connection with the question of the length of phenotypic lag. It is concluded that there is no evidence that compels the interpretation that the phenotypic expression of a genetic change requires a long time, or even one division, for its completion.