TABLE 2.

Effects of carbon starvation on expression of AST in wild-type S. typhimurium and its crp::Tn10 and argR::Tn10 derivatives

Genotypec	Supplementa	Sp act (nmol/mg/min)b
Wild type	0.2% Glucose	<0.1
	0.2% Glucose+Arg	<0.1
	0.03% Glucose	53 (4)
	0.03% Glucose+Arg	68 (2)
crp::Tn10	0.03% Glucose	<0.1
	0.03% Glucose+Arg	<0.1
argR::Tn10	0.03% Glucose	<0.1
	0.03% Glucose+Arg	<0.1

^aCells were grown in minimal medium (6) containing 20 mM (NH₄)₂SO₄ at 37°C. The final concentration of glucose in the culture was either 0.2% for carbon excess or 0.03% for carbon starvation. Cultures supplemented with 0.03% glucose ceased growth at an optical density of 0.5 at 600 nm and were harvested 2 h after glucose depletion. Arginine (Arg) was added at 20 mM. During logarithmic growth, the doubling time for the wild type and its argR derivative was 50 min whereas the doubling time for the crp derivative was 75 min. 

^bSee footnote b of Table 1. 

^cThe crp::Tn10 locus from strain PP1037 (Salmonella Genetic Stock Center) was introduced into the wild type by phage P22 transduction. The argR::Tn10 derivative was previously characterized (15).