Fig. 6
From: A rapid and efficient strategy for combinatorial repression of multiple genes in Escherichia coli
Combinatorial repression of PEP-consuming genes to optimize the biosynthesis of NeuAc. (A) The biosynthesis pathway of NeuAc. The blue arrows indicate the biosynthesis pathway of NeuAc. The “×” indicates the metabolic pathways that have been knocked out by the DN5 strain. The red arrows indicate the CRISPRi targeting genes designed for repression; (B) The effect of combinatorial repression of PEP-consuming genes on NeuAc production. PlacO1 expresses sgRNA-pta targeting pta. PLtetO−1 expresses sgRNA-ptsI targeting ptsI. ParaBAD expresses sgRNA-pykA targeting pykA. “-” indicates that no inducer is added, and “+” indicates that the inducer is added. Strains without sgRNA targeting any genes were used as controls. Different combinations of inducers were added when the strain was transferred to the shake flask. After 48 h of fermentation in shake flasks, the titers of NeuAc were measured. Data are expressed as means (± s.d.) from three independent experiments