Figure 5.

Nitrate utilization promotes S. Typhimurium growth under low-oxygen conditions. (a) S. Typhimurium WT strain was cultured in N-minimal medium in the presence of 0, 15, 30, or 45 mM nitrate for 6 h. The growth promotion index (GPI) of nitrate was calculated according to the OD₆₀₀ of the bacterial culture supplemented with nitrate divided by that without nitrate. (b) S. Typhimurium WT strain was cultured in N-minimal medium in the presence or absence of 30 mM nitrate for 6 h with different oxygen levels. (c) S. Typhimurium WT strain was cultured in N-minimal medium under low-oxygen or normal-oxygen conditions with different carbon sources (35 mM glucose, 70 mM pyruvate, or 70 mM lactate) in the presence or absence of 30 mM nitrate. Absorbance of the bacterial suspension at 600 nm (OD₆₀₀) was measured at 6 h. (a–c) Data were generated from three independent experiments and are presented as mean ± SD. p-values were determined using unpaired Student’s t-test (* p < 0.05; ** p < 0.01; ns, not significant).