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Fig. 3 | Microbial Cell Factories

Fig. 3

From: Metabolic engineering of Escherichia coli for optimized biosynthesis of nicotinamide mononucleotide, a noncanonical redox cofactor

Fig. 3

Pathway combination and strain modification improved NMN+ production. NadV homologs were co-overexpressed with and without F. tularensis NadE* in wild type and ΔpncC cells. In wild type cells, introducing F. tularensis NadE* and NadV homologs only resulted in low levels of NMN+ accumulation. Disrupting the NMN+ degrading-enzyme PncC greatly increased intracellular NMN+ levels. When the NadV homologs were expressed without F. tularensis NadE*, intracellular NMN+ levels decreased for all candidates except H. ducreyi. In some cases, only expressing NadV caused a significant growth detriment (shown as n.d.). Of the NadV homologs tested, R. solanacearum NadV demonstrated the highest intracellular NMN+ production of ~ 1.5 mM in ΔpncC cells, a 130-fold increase over the cell’s basal level when expressed with F. tularensis NadE*. Cells were grown in 2xYT medium supplemented with 1 mM nicotinamide at 30 °C for 4 h. NMN+ concentration was determined by LC-MS. Ft Francisella tularensis, Hd Haemophilus ducreyi, Rs Ralstonia solanacearum, Ss Synechocystis sp., SynE Synechococcus elongatus, n.d not determined due to poor growth

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