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. 2012 Sep 13;7(9):e44797. doi: 10.1371/journal.pone.0044797

Figure 2. Bacterial growth in tryptophan-free medium with additional L-tryptophan or 1-L-MT.

Figure 2

(A) Staphylococcus aureus was cultured in medium with denoted supplementation of L-trp (black), D-trp (blue), 1-L-MT (red) or 1-D-MT (green) (100 µg/mL each). After 18 h, bacterial growth was determined photometrically. Asterisks indicate significant increase of bacterial growth compared to the 1-L-MT group (p<0.05). (B) Long-term culture of Staphylococcus aureus. Bacteria were cultured within tryptophan-free culture medium with or without L-tryptophan or 1-L-MT (100 µg/mL each) and bacterial growth within each culture was determined after 18 h photometrically. Thereafter, the bacterial culture was diluted in PBS serially and 10 µl were used to infect new tryptophan-free culture medium, according to 10–100 CFU/well. Asterisks mark no significant difference (p<0.05) in the 1-MT group, compared to tryptophan. (C) Different bacterial strains were grown in tryptophan-free medium with additional L-tryptophan or 1-L-MT (100 µg/mL each) for 18 h. Asterisks mark no significant difference (p<0.05) in the 1-MT group, compared to tryptophan.. All data are given as bacterial growth, determined by optical density at 620 nm, +/− SEM of triplicates of three independent experiments (A) or +/− SD of duplicates of one representative experiment (B, C).