Fig 2. Endogenous urea is not utilized as a nitrogen source.

(A) S. aureus arginine catabolism and nitrogen flow (nos encodes nitric oxide synthase, arcA1/arcA2 encodes arginine deiminases, rocF encodes arginase, ureABCEFGD encodes urease, and glnA encodes glutamine synthetase). (B) JE2 WT was cultured in CDM containing ¹⁵N-serine whereas both JE2 WT and JE2 Δure were cultured in CDM containing ¹⁵N-arginine. The intracellular ¹⁵N-glutamine levels were measured by NMR (n = 5/strain, mean ± SEM). Statistical significance was assessed using one-way ANOVA followed by Tukey's post-test; *** P < 0.001; ns, not significant. (C) WT and Δure were cultured in CDM with ¹⁵N-arginine, and the extracellular ¹⁵N-urea levels were measured by NMR (n = 5/strain, mean ± SEM).