The maximal response can be observed at 101 �� 4 min. In this work, we present the first quantitative analysis of the expression dynamics of the Colicin E2 operon in E. coli. Using single cell time-lapse microscopy, we thereby distinguished between the expression dynamics of the cea gene encoding the toxin Colicin E2 and the cel gene responsible for colicin release. As described in the introduction, two different types of mRNA can be produced: long and short mRNA, but only the long mRNA also includes the cel gene. In addition, binding sites for the mRNA binding protein CsrA are present in the RBS of the cel gene, introducing post-transcriptional regulation of cel gene expression via translation inhibition by CsrA. By exchanging the cea and cel genes with fluorescent reporter genes while keeping all regulatory elements, we were addressing two questions: a) is the heterogeneous gene expression of cea and cel different and b) do we see differences in the onset of cea and cel gene expression. In contrast to our expectations, we did not observe a significant difference in cea and cel gene expression in strain EMO3-C. In addition, the onset of gene expression was similar for both genes, indicating that post-transcriptional translation inhibition of the cel gene by CsrA did not occur or was not detectable under the experimental conditions used in this study. Although, CsrA has been described to be a high abundance protein, the additional introduction of our double reporter plasmid could lead to a titration of CsrA and thereby affect inhibition of cel gene expression via CsrA in strain EMO3-C. Furthermore, two sRNAs, CsrB and CsrC have been reported to bind CsrA. Increased expression of these sRNAs could reduce the amount of free CsrA, which in turn could affect the time-point of colicin release. Nevertheless, in agreement with previous whole population studies, our single cell time-lapse microscopy data confirm that the cea and cel genes of the Colicin E2 operon are heterogeneously expressed in the stationary phase. Similarly, whole population studies of other VE-822 colicins such as Colicin K revealed that these colicins are also heterogeneously expressed, indicating a common mechanism. With induction of the Colicin E2 operon by the SOS chemical MitC, the fraction of cells expressing either cea or cel increased with the applied MitC concentration and the cells�� response times decreased PF-4217903 side effects exponentially in dependence of the MitC concentration, saturating at 60 min. These data suggested that even very low exogenous stress levels can be sensed by individual cells, but cells are not able to produce and release the colicin prior to 60 min after induction by MitC.