Fig. 2

Fluorescence intensity of L. lactis (LAC; red), Lb. plantarum (PLA; blue) and E. coli (ECO; green) expressing IRFP713. a Fluorescence intensity was normalized to OD₆₀₀ = 1.0. Growth media of corresponding bacteria (GM17 M17 medium with 0.5 % glucose, LB lysogeny broth, MRS De Man, Rogosa and Sharpe medium) were used as negative controls. b Fluorescence intensity of bacterial cells as a function of optical density (cell concentration). Correlation coefficients (R²) for individual curves are depicted in corresponding colors. FU fluorescence units, OD ₆₀₀ optical density