Fig. 3

Intracellular metabolite pools in response to nitrogen limitation. Intracellular metabolite concentrations were measured and dry weight normalized after one and nine hours at C/N = 150 and nine hours at C/N = 10. Average fold change from three replicates each of (a) nitrogen containing metabolites and (b) non-nitrogen containing metabolites was calculated at nine hours for C/N = 150 vs. C/N = 10 (black bars) and for C/N = 150 at 9 vs. 1 h (grey bars). *significantly changing intracellular metabolites (p < 0.01). Arginine hydrolyzes to ornithine during chemical derivatization for GC-MS, thus ornithine represents a pooled value for intracellular ornithine and arginine