Fig 3.

H₂O₂ sensitivity in the wild-type P. stewartii (DC283), the crtB∷Mar2xT7 (crtB) mutant, and the crtB∷Mar2xT7/pMOJ14 (crtB/crtB⁺) complemented strain. Mid-log-phase cells were treated with H₂O₂ to a final concentration of 40 mM for 30 min. Controls were left untreated with H₂O₂. CFU were enumerated, and the percent growth inhibition was normalized to that for the untreated control. The crtB∷Mar2xT7 (crtB) mutant was significantly more sensitive to H₂O₂ treatment than WT DC283. H₂O₂ tolerance was fully restored when a wild-type copy of crtB was supplied in trans on plasmid pMOJ14 in strain crtB∷Mar2xT7/pMOJ14 (crtB/crtB⁺).