Table 3

Effect of the constitutive expression of amtB on growth of an S. typhimurium gltB mutant strain at different pH values and ammonium concentrations

Strain[NH4+],* mMpH 7 pH 6
510.5510.5
SK2633575863606566
 (wild type)
SK3390626362656864
 (wild type/Ptac-amtB)
SK306265105160111700≈1,130
 (gltB)
SK339168106160105360450
 (gltB/Ptac-amtB)
SK310960636866115142
 (gltB gdhp515)
SK33926468697088108
 (gltB gdhp515/Ptac-amtB)
  • Data are doubling time (min). Cells were grown in NC medium with glucose as carbon source and ammonium as sole nitrogen source. The glucose concentration was 0.4% at 5 mM ammonium and 0.2% at lower ammonium concentrations. Isopropyl β-d-thiogalactoside was present at 1 mM. 

  • * [NH4+ + NH3]. 

  • The lesion is ΔgltB824 (31).