Enhanced d-pantothenic acid biosynthesis by plasmid-free Escherichia coli through sodium pyruvate addition combined with glucose and temperature control strategy.

This article focuses on enhancing the production of d-pantothenic acid (d-PA), a vital vitamin used in feed, pharmaceutical, and food industries, through fermentation using a plasmid-free recombinant Escherichia coli strain (DPAN19). The study optimized the fermentation medium via Plackett–Burman and Box–Behnken designs, achieving a 39.5% increase in d-PA titer in shake flasks. Further improvements were made in a 5-liter fermenter by implementing a two-stage temperature control strategy, a two-stage glucose feeding regimen, and supplementation with sodium pyruvate, culminating in a d-PA titer of 72.90 g l⁻¹. These integrated fermentation strategies demonstrate potential for cost-effective industrial-scale d-PA production without the use of plasmids, antibiotics, or inducers, and provide a reference framework for optimizing microbial synthesis of related metabolites.