Growth of Y. pestis strains at 37 °C across PMH2-DIP gradient plates (0–100 μM DIP). The results represent the mean from two independent experiments of incremental growth across the gradient by 48 h of incubation. Error bars, sd. Strains: YbtT++, KIM6-2072(pYbtT-H6) positive control; YbtT-S94A, KIM6-2072(pYbtT-S94A-H6); YbtT-H230A, KIM6-2072(pYbtT-H230A-H6); YbtT−, KIM6-2072 (ΔybtT2072) negative control; YbtT-G92A, KIM6-2072(pYbtT-G92A-H6); YbtT-G96A, KIM6-2072(pYbtT-G96A-H6); Ybt+, KIM6+ positive control.