FIG 2.

YbtPQ is not required for Ybt synthesis in UPEC. Yersiniabactin production was determined from the culture supernatants of UTI89 strains using quantitative liquid chromatography-tandem mass spectrometry methods. While salicylate synthesis-deficient strain UTI89 ΔybtS showed a decreased level of Ybt production, the level of Ybt production by strain UTI89 ΔybtPQ::Kan^r showed no difference from that by the wild type. UTI89 ΔybtPQ::Kan^r/pybtPQ showed an increased level of Ybt synthesis compared to that of the wild type. Results are shown as means ± SDs (n = 3). **, P < 0.005; ***, P < 0.0005; NS, not significant.