Figure 1. sseL::lacZ is induced in response to low phosphate, low magnesium and acidic pH environmental cues.

S. Typhimurium strains carrying sseL:lacZ were grown for 16 h at 37°C in LB, LPM (pH 7.4) LPM (pH 5.8) supplemented with 10 mM MgCl₂, and LPM (pH 5.8), and were assayed for β-galactosidase activity presented in Miller units (M.U.). Basal lacZ expression of S. Typhimurium harboring pMC1403 (vector) that was grown in LPM (pH 5.8) is also shown.