Single cell analysis of Escherichia coli outer membrane porin composition in response to nutrient depletion

Characterization of outer membrane integrity into isoclonal population of Escherichia coli using fluorescent probe specific to cell viability: propidium iodide (PI) staining; combined to FACS cytometry and proteomic studies of sorted subpopulations. The results tend to reveal two distincts cellular strategies: Cells positively probed by PI offer a high outer membrane protein (OMP) content, indicating nutrient competence in response to substrate limitative conditions. Unprobed cells, characterized by a low OMPs rate, could suffer from growth arrest and develop stress responses (Crp, Cra, RpoS,RpoN, RpoH-dependent).