Relative fluorescence of zmsK (p P desAB -Gfp), zmsA (p P desAB -Gfp), and Dz974 upon exposure to zeamines (+) or not (-). Bacterial strains were cultured in 96-well plates containing LS5 medium with exogenous addition of zeamines (+) or not (-), at 28 C for 48 h. After incubation, cell culture dilutions were transferred into 96-well black clear-bottom plates for measuring optical density at 600 nm (OD 600 ) and fluorescence density (excitation at 485 nm and emission at 535 nm). The fluorescence of bacterial strain was calculated by dividing its fluorescence density reading with its optical density reading. The relative fluorescence of bacterial strain was expressed as the fluorescence of bacterial strain normalized to the fluorescence of zmsK (p P desAB -Gfp) with the same treatment. The relative fluorescence is presented as mean SE, n = 3. Statistical analysis was performed using a two-tailed unpaired Student’s t test versus zmsK (p P desAB -Gfp). * P < 0.01.
