Nicotinamide Mononucleotide Production in Metabolically Engineered Saccharomyces cerevisiae

Area of Science:

• Biotechnology
• Metabolic Engineering
• Yeast Fermentation

Background:

• Nicotinamide adenine dinucleotide (NAD+) is vital for cellular energy and metabolism.
• Nicotinamide mononucleotide (NMN) is a direct NAD+ precursor with antiaging potential.
• Microbial NMN production offers a sustainable alternative to chemical synthesis.

Purpose of the Study:

• To optimize NMN production in Saccharomyces cerevisiae.
• To compare the efficacy of constitutive (TEF1) versus inducible (GAL1) promoters for NMN biosynthesis.
• To enhance intracellular NMN and NAD+ yields through genetic engineering and media optimization.

Main Methods:

• Engineered yeast strains (S. cerevisiae BY4742) to express human nicotinamide phosphoribosyl transferase (h-NAMPT) and yeast PRS genes.
• Utilized TEF1 (constitutive) and GAL1 (inducible) promoters for gene expression.
• Optimized fermentation conditions using rich R-SD medium.

Main Results:

• Constitutive TEF1 promoter yielded higher intracellular NMN and NAD+ than the GAL1 promoter.
• The scTEF2g strain achieved a record 151.71 mg/L intracellular NMN from nicotinamide in flask fermentation.
• This represents a 3-fold increase in NMN yield compared to control strains.

Conclusions:

• Promoter selection is crucial for maximizing NMN production in yeast.
• Optimized yeast fermentation presents a viable platform for NMN biosynthesis.
• This study achieved the highest reported intracellular NMN yield in recombinant yeast from nicotinamide.