Dynamic Regulation of Transporter Expression to Increase L-Threonine Production Using L-Threonine Biosensors

The cytotoxicity of overexpressed transporters limits their application in biochemical production. To overcome this problem, we developed a feedback circuit for L-threonine production that uses biosensor to regulate transporter expression. First, used IPTG-induced rhtA regulation, exporter, simulate dynamic regulation improving production, and the results show it had significant advantages compared with constitutive overexpression rhtA. further construct auto-regulation, three sensing promoters, PcysJ, PcysD, PcysJH, were characterized gradually decreasing strength. expression threonine-activated promoter considerably increased (21.19 g/L) beyond attainable by (8.55 g/L). Finally, autoregulation method was regulating rhtB rhtC improve achieve high titer 26.78 g/L (a 161.01% increase), yield 0.627 g/g glucose, productivity 0.743 g/L/h shake-flask fermentation. This study analyzed detail influence on For first time, confirmed dynamically levels can efficiently promote using end-product biosensor.