Fig. 3. (A) Appropriate reactions for up-regulation (top) and down-regulation (bottom) predicted by the proposed systemic approach under phototrophic condition. (B) An overview of the metabolic pathways influencing NADH production; the reactions indicated by green arrows are suitable candidates for up-regulation, whereas red dashed lines should be down-regulated. Besides, reactions that do not contribute to NADH enhancement were shown with the black dotted line. (C) Acetate consumption via ACS, and series reactions of ACKr_f and PTAr_b. The suffixes _f and _b were used for reactions that occurred in the forward and backward directions, respectively. The entire name of all reactions and metabolites was given in the Supplementary file (Tables S3 and S4).