Fig. 1

Main biological pathways for cytidine synthesis in E. coli. Precursor synthesis is divided into the pentose phosphate pathway, glycolysis, and the TCA cycle, which provide the necessary precursors for cytidine synthesis. UMP synthesis primarily involves the production of uridylic acid (UMP). The cytidine synthesis pathway utilizes UMP as a precursor to synthesize cytidine. The boxed section in the figure highlights the gene editing aspect of this study, with the red X indicating the site of knockout [17]