Fig. 4: Enhancement of SA production by dynamically and simultaneously controlling multiple metabolic fluxes.

a Schematic construction of layered dynamic control circuits for regulation of the SA biosynthetic pathway. b The effect of different triggering OD of QS variants driving entC-pchB expression on SA titer. Gray bars represent SA titers generated by the strains harboring partial QS circuits in the absence of the gene luxI. Red bars represent SA titers generated by the strains harboring entire QS circuits in the presence of the gene luxI. c The effect of different triggering OD of QS variants driving entC-pchB combined with different ppc downregulation levels on SA titer. d The effect of three-layered dynamic regulation strategy on SA titer in wildtype E. coli strain. The upregulation module containing SA pathway genes was controlled by the QS variant P_QS37, the downregulation module carrying the CRISPRi system was controlled by the QS variant P_QS18, and the APTA module was controlled by QS variant P_QS13, P_QS18, P_QS37, or P_QS33, respectively. e The effect of three-layered dynamic regulation strategy on SA titer in QH4 strain. The upregulation module containing SA pathway genes was controlled by the QS variant P_QS37, the downregulation module carrying the CRISPRi system was controlled by the QS variant P_QS18, the APTA module was controlled by QS variant P_QS13, P_QS18, P_QS37, or P_QS33, respectively. NA represents the SA titer generated by the control strain lacking the APTA module. Genes: tktA encodes transketolase, ppsA encodes phosphoenolpyruvate synthase, aroG encodes 3-deoxy-D-arabinoheptulosonate-7-phosphate (DHAP) synthase, aroL encodes shikimate kinase, ppc encodes phosphoenolpyruvate carboxylase, entC encodes isochorismate synthase, pchB encodes isochorismate pyruvate lyase. Metabolites: E4P D-erythrose-4-phosphate, PEP phosphoenolpyruvate. Data shown are mean ± SD (n = 3 independent experiments). Source data are provided as a Source Data file.