Dynamic Regulation of the l-Proline Pathway for Efficient l-Arginine Production in Escherichia coli

Abstract

l-Arginine, a semiessential amino acid crucial for human health, has broad applications in cosmetics, nutraceuticals, feed, and pharmaceuticals. In this study, we developed an Escherichia coli strain with enhanced l-arginine production by deregulating negative feedback, enhancing the synthesis pathway, and increasing precursor and cofactor availability. The engineered strain achieved titers of 6.41 g/L in shake flasks and 63.9 g/L with a yield of 0.31 g/g of glucose in a 5 L fermenter. Blocking the competitive l-proline synthesis pathway elevated the l-arginine titer to 9.36 g/L but reduced the biomass. To fine-tune l-proline synthesis without exogenous l-proline, we developed a dynamic regulatory method for proB gene control. The final strain, harboring proB driven by a temperature-sensitive promoter, achieved 65.6 g/L l-arginine with a yield of 0.42 g/g glucose in a 5 L fermenter. Balancing growth and production through dynamic regulation of the l-proline pathway presents a viable strategy for refining l-arginine bioproduction.