Figure 4

Growth of the wild-type and ∆nnaR, ∆glnR, ∆nnaR–attB::_phspnnaR, ∆glnR-attB:: _pglnRglnR M. smegmatis strains on solid medium: Middlebrook 7H10/OADC, Yeast Nitrogen Base Agar without nitrogen source and Yeast Nitrogen Base Agar with sodium nitrate (10 mM) (A). The images are examples of three biologically independent experiments. (B) Growth kinetics and survival of the wild-type and ∆nnaR, ∆glnR, ∆nnaR–attB::_phspnnaR, ∆glnR-attB::_phspnnaR M. smegmatis strains on nitrogen-limiting Sauton’s medium containing sodium nitrate (10 mM) and sodium nitrite (5 mM). The kinetics of growth were evaluated by measuring the absorbance at 600 nm at the indicated time points. The number of viable cells at 24 hours was counted by the CFU method. The displayed values are the average ± standard deviation from three independent experiments. The statistical significance was determined using Student’s t-test (*p < 0.03): for ∆nnaR, ∆glnR, ∆glnR–attB::_phspnnaR p < 0.001 (CFU on sodium nitrate), for ∆nnaR, ∆glnR, ∆glnR–attB::_phspnnaR p < 0.001 (CFU on sodium nitrite).