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. 2015 Apr 15;83(5):1830–1844. doi: 10.1128/IAI.03016-14

FIG 6.

FIG 6

SCVs are more resistant to H2O2 than wild-type bacteria. (A) The survival of wild-type SH1000 S. aureus (○) or a derived SCV isolate (□) during exposure to 30 mM H2O2 was determined by quantifying CFU. Survival of the SCV was significantly greater (P < 0.05) than that of the wild type at the 45- and 60-min time points. (B) Survival of three independently isolated, menadione-auxotrophic SCVs from cultures without (TSB) or with H2O2 or paraquat (para) was determined after 60 min of exposure to 30 mM H2O2. The survival of the wild type after 60 min is shown for comparison. The survival of all SCV isolates was significantly greater than that of the wild type. (C) Survival of independently isolated SCVs with auxotrophy for hemin (H), CO2 (C), menadione (M), fatty acids (F), or where auxotrophy has not been established (?) after 60 min in 30 mM H2O2. (D) Survival of wild-type or various, independently isolated menadione-auxotrophic SCVs from cultures without oxidants, grown in the absence (−) or presence (+) of menadione. Supplementation of SCV but not wild-type cultures with menadione significantly reduced survival in the presence of H2O2. (E) Growth of S. aureus SH1000 in the presence of the electron-transport chain inhibitor HQNO (Gro) promotes resistance to H2O2 relative to growth in TSB only (Ctl) or growth in TSB, followed by addition of HQNO to bacteria 5 min prior to H2O2 exposure (Post). (F) Survival of the USA300 wild-type strain and derived deletion mutants lacking hemB or menD after incubation in 25 mM H2O2. Survival of the SCVs was significantly greater than WT. (G) Survival after incubation in 25 mM H2O2 of USA300 hemB and menD mutant strains transformed either with pCL55 or PCL55 containing the hemB (phemB) or menD (pmenD) coding sequences. Survival of complemented strains was significantly lower than that of mutants transformed with vector alone (pCL55). (H) Survival of a clinical menadione-auxotrophic SCV (CX003SCV) and derived revertant (CX003WT) with the wild-type phenotype after incubation in 30 mM H2O2. Survival of the SCV was significantly greater than wild-type after 60 min. Significance was determined by using a Student t test corrected for multiple comparisons via the Bonferroni method and declared significant when P < 0.05.