Figure 3. Complementation by pcadA and analysis of ΔadiAΔspeF during growth at moderate acidic pH.

Bacteria grown overnight in LBG pH 7 were washed and diluted to OD₆₀₀ = 0.03 in M9 medium complemented with 5 mM L-lysine, 0.1% casamino acids, 0.2% glucose and adjusted to pH 4.5 with HCl. pACYC177 is a low-copy cloning vector and pcadA is pACYC177 in which the cadA gene has been introduced under control of its natural promoter. Cultures were either performed in anoxic (A) or aerobic (B) conditions and monitored by following optical density at 600 nm. Panels C and D show growth of the WT and ΔadiAΔspeF strains in the same M9 medium complemented or not with 5 mM lysine, at pH 4.5 in anoxic (C) and aerobic (D) conditions.