Figure 3. Inhibition of E. coli growth by serine and cysteine.

E. coli MG1655 cells were grown at 34°C in M9 minimal medium [29] supplemented with 10 µg/ml thiamine and either 0.4% glycerol and four amino acids (Gly+AA) or 0.4% glucose (Glc). Indicated amounts of L-serine or L-cysteine were added after 2 hours of growth. Relative growth rate was determined as the difference between the optical density of the culture at 600 nm after 3.5 h and 5 h of growth, normalized to the value of a control culture grown without serine or cysteine. Adaptation precision for serine and cysteine was replotted from Fig. 1B.