The impact of the cells' physiological status, density, and nutrient availability on the formation of persisters were also determined, which were isolated and screened using the antibiotic Gentamicin at a dose of 100 milligrams per liter (mg/L). The researchers found that the physiological status differences between strains brought by culture preparation methods—specifically, plate-grown versus broth-grown—did not impact persister formation. However, higher persister ratios were found when cell density increased.

Next, the formation of persister cells under simulated packinghouse conditions was tested by artificially inoculating stainless steel coupons with L. monocytogenes suspending in media with decreasing nutrient levels: brain heart infusion broth (1,366 mg/L of oxygen), produce-washing water with various organic loads (1,332 mg/L O2 and 652 mg/L O2), and sterile Milli-Q water. The pathogen survived in all suspensions at 4 °C with 85 percent relative humidity for seven days, although two of the three strains saw persister cell levels decline in nutrient-poor media over time. Persister populations decreased along with total viable cells, demonstrating the impact of available nutrients on the formation of persisters.

Finally, the chlorine sensitivity of L. monocytogenes persister cells was evaluated and compared with regular L. monocytogenes cells. Results showed that, despite their increased tolerance to gentamicin, the persisters were more susceptible to the chlorine treatment (100 mg/L for 2 minutes) than the regular cells.