Figure 2. Amino acid-dependent growth of the eleven GFP-labeled biosensors.

Each biosensor was cultivated in minimal medium, to which increasing concentrations of the required focal amino acid have been added. Cell growth was measured either turbidometrically (OD_{600 nm}, ▪) or as relative fluorescence units (RFU, Δ) after 18 h (histidine, arginine, tryptophan, isoleucine, methionine, phenylalanine, tyrosine, proline and lysine) or 24 h (leucine and threonine) of cultivation. Means (±95% confidence interval) of four replicates are given.