Persister cells form based on low ribosome content in Escherichia coli

Persister cells survive severe stresses, including antibiotics, starvation, heat, oxidative conditions, and phage attack, by entering a dormant physiological state. They arise without genetic change and can resume growth once the stress is removed and nutrients are available. Critically, upon resuscitation, disease-causing persister cells can reconstitute infections. Although it is known that persister cells resuscitate in proportion to their ribosome content, it has remained unclear whether ribosome levels also influence the formation of persister cells. Here, we used fluorescence-activated cell sorting (FACS) to fractionate exponentially growing Escherichia coli cells into four populations spanning low to high ribosome levels and demonstrated, via antibiotic survival assays with both ampicillin and ciprofloxacin, that cells with low ribosome content form persister cells approximately 80-fold (ampicillin) and 50-fold (ciprofloxacin) more frequently than cells with population-average ribosome levels. These findings show that persister cell formation is inversely proportional to ribosome abundance. Cells with low ribosome levels are less metabolically active and therefore less capable of initiating stress responses like most cells; instead, they enter a dormant state in which antibiotic target activity is reduced, thereby promoting persister formation.