Fig. 2
Development, test and optimization of the l-threonine biosensor. A Sequence analysis of promoters. Sequence analysis of PcysK, PcysJ, PcysD, and PcysP promoters, highlighting the binding site of CysB protein. B Fluorescence values of the sensor at 0, 10, 20, and 30 g/L l-threonine concentration after deletion of the binding site of CysB protein in promoters PcysD, PcysJ, PcysP, and PcysK. C Schematic diagram of the pSensor biosensor structure. D Characterization of the performance of biosensors pSensor and PcysK-egfp. The x-axis represents different concentrations of l-threonine, and the y-axis represents the change in intracellular green fluorescence intensity after induction. E Identification of the response range of the biosensor pSensor to l-threonine