Fig 4.

Nonheritability nature of S. mutans persister phenotype. An overnight culture of UA159 WT strain was diluted to the early logarithmic phase and immediately treated with ofloxacin (20 μg/ml) for 24 h. The surviving cells were then regrown into fresh antibiotic-free THYE broth until the stationary phase was reached and then diluted to early logarithmic phase and immediately treated with ofloxacin (20 μg/ml) for 24 h. The procedure was repeated three times. The results showed that persisters are phenotypic variants of the parental strain that arise in a clonal population of genetically identical cells.