Fig 7.
Acid resistance of a ΔphoPQ23 mutant containing rhamnose-regulated arginine decarboxylase. Ty2, χ11500 (ΔadiA-adiC), χ8444 (ΔphoPQ), and χ11622 (ΔphoPQ PrhaBAD adiAC) were grown to the stationary phase in EGA medium containing 0.1% rhamnose and then challenged with EG medium containing 1 mM arginine at pH 3.0 for 4 h (A) or pH 2.5 for 1 h (B). Survival in all assays was monitored by plating on LB agar containing all necessary supplements. The data shown are the means and SEM from three independent assays. Pairs of data marked with an asterisk are significantly different (P < 0.05).