Comparison of Starvation-Induced Persister Cells with Antibiotic-Induced Persister Cells.

The phenotypic heterogeneity in a large population arises because of fluctuation in microenvironments and stochastic gene expressions. In this report, we isolated two types of persistent sub-populations of Vibrio cholerae, one triggered by starvation and another by antibiotics. We characterised starvation-induced (E-cells) and antibiotic-induced (P-cell) persister cells for stress tolerance, colony morphology and toxin gene expressions. Both the sub-populations differ with respect to morphology, temperature tolerance and oxidative stress tolerance. The E-cells were smaller than the P-cells and formed tiny colonies (1-2 mm). The E-cells were more sensitive to heat and oxidative stress compared with P-cells. The up-regulated genes of P-cells include, genes of antioxidant enzymes (>5 fold), cholera toxin (>26 fold) and toxin: antitoxin protein hipA (>100 fold). Upon nutrient up-shift, the E-cells recovered after lag time of 6 h. However, such lag extension was not visible during P-cell recovery, suggesting that P-cell physiology is more akin to normal cells than E-cells. This is the first comparative report on the two different persister sub-populations of V. cholerae. The E-cells and P-cells are similar regarding antibiotic tolerance. However, the sub-populations differ significantly in stress tolerance and other phenotypes studied.