Complementation of the selleck kinase inhibitor sucB and ubiF mutants with the functional sucB and ubiF genes restored the wild-type level susceptibility to the antibiotics in both MIC and MBC tests, whereas the mutants transformed with vector control remained susceptible to the antibiotics like the mutants alone (Table 1). To determine the susceptibility of stationary phase cultures of the sucB and ubiF mutants to various antibiotics, the stationary phase cultures with log phase cultures as a control were exposed to ampicillin and gentamicin and the survival of the mutants at different

time points was assessed. Antibiotic exposure of the log phase and stationary phase cultures showed that both the sucB and ubiF mutants were more susceptible than the parent strain to ampicillin and gentamicin. For log phase cultures,

both sucB and ubiF mutants were completely killed after ampicillin (100 μg mL−1) or gentamicin (20 μg mL−1) exposure for 1 day, whereas a portion of the parent control strain BW25113 cells survived (Table 2). Complementation of the mutants restored the level of persisters to the wild-type level in the antibiotic exposure DAPT ic50 assays. For stationary phase cultures, both the sucB and ubiF mutants were initially killed to the same extent as the parent strain BW25113 during the first 3-day ampicillin (100 μg mL−1) or gentamicin (40 μg mL−1) exposure, but both mutants showed lower level of persisters than the parent strain after 6 days or longer (Table 3). Again, complementation of the sucB and ubiF mutants restored the level of persisters to that of the parent strain, whereas the mutants transformed with vector control behaved

like the mutants alone in having lower number of persisters (Table 3). It is worth noting that the sucB and ubiF mutants alone without antibiotics did not lose significant viability compared with those exposed to antibiotics in the exposure assay, Ribonucleotide reductase indicating that the decreased persister survival in the mutants is genuine and not due to a nonspecific loss of viability in the absence of antibiotics during the exposure time period (see Table 2). This has been found to be true in other experiments of this study. Overnight stationary phase cultures of the sucB and ubiF mutants and their complemented strains along with the parent strain BW25113 were exposed to H2O2 at 12.5, 25, 50 and 100 mM for 4 h and the number of persisters was assessed on LB plates. The sucB mutant was much more susceptible to peroxide than the ubiF mutant and the parent strain, as the sucB mutant was completely killed by H2O2 at 25 mM and above (not shown). The ubiF mutant was more sensitive to H2O2 than the parent strain at 100 mM, as the ubiF mutant had no surviving bacteria.