Figure 2. Yersinia HPI mutants of a model urinary pathogenic E.coli strain exhibit increased or decreased yersiniabactin expression in a standard minimal media condition.

Strains were cultured in M63 minimal medium+glycerol for 18 hours at 37 C and yersiniabactin levels in the media were determined by stable isotope dilution quantification using ¹³C-labeled internal standard. Mutants strains lacking genes for transport (fyuA, ybtP, ybtQ) or a gene of unknown function (ybtX) exhibited preserved or elevated yersiniabactin levels. Results are expressed as LC-MS/MS peak area of unlabeled (¹²C) analyte to internal standard (¹³C).