AUTHOR=Tan Zhilei , Yang Yihang , Wu Yannan , Yan Jiajia , Zhang Bin , Hou Ying , Jia Shiru 

TITLE=Biosynthesis of β-nicotinamide mononucleotide from glucose via a new pathway in Bacillus subtilis

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1405736

DOI=10.3389/fmicb.2024.1405736

ISSN=1664-302X

ABSTRACT=<sec id="sec1001"><title>Introduction</title><p>β-nicotinamide mononucleotide (β-NMN) is an essential precursor of nicotinamide adenine dinucleotide (NAD<sup>+</sup>) and plays a key role in supplying NAD<sup>+</sup> and maintaining its levels. Existing methods for NMN production have some limitations, including low substrate availability, complex synthetic routes, and low synthetic efficiency, which result in low titers and high costs.</p></sec><sec id="sec2001"><title>Methods</title><p>We constructed high-titer, genetically engineered strains that produce NMN through a new pathway. <italic>Bacillus subtilis</italic> WB600 was used as a safe chassis strain. Multiple strains overexpressing <italic>NadE</italic>, <italic>PncB</italic>, and <italic>PnuC</italic> in various combinations were constructed, and NMN titers of different strains were compared via shake-flask culture.</p></sec><sec id="sec3001"><title>Results</title><p>The results revealed that the strain <italic>B. subtilis PncB1-PnuC</italic> exhibited the highest total and extracellular NMN titers. Subsequently, the engineered strains were cultured in a 5-L fermenter using batch and fed-batch fermentation. <italic>B. subtilis PncB1-PnuC</italic> achieved an NMN titer of 3,398 mg/L via fed-batch fermentation and glucose supplementation, which was 30.72% higher than that achieved via batch fermentation.</p></sec><sec id="sec4001"><title>Discussion</title><p>This study provides a safe and economical approach for producing NMN on an industrial scale.</p></sec>