Figure 8.

Model of evolution of antibiotic resistance through epigenetic inheritance. Within an isogenic population of E. coli there is random variation in expression levels of genes. Antibiotic exposure (horizontal arrows) selects cells with gene expression patterns that allow survival. For example, elevated expression of the GadA and β-lactamase genes promote ampicillin survival. A combination of continued selection, epigenetic inheritance and stochastic variation can evolve populations with gene expression patterns providing increasing antibiotic resistance.