Recent advances in metabolic engineering of Escherichia coli for riboflavin biosynthesis

Escherichia coli has emerged as a promising microbial platform for industrial riboflavin (RF) biosynthesis, enabled by systematic metabolic engineering of its well-characterized genetic system. This minireview synthesizes key strategies for enhancing RF production, focusing on: (i) Precursor optimization through reinforced pentose phosphate pathway flux (elevating ribulose-5-phosphate) and deregulated purine biosynthesis (boosting GTP availability); (ii) Pathway engineering via rib operon overexpression coupled with feedback inhibition relief through ribF modulation and FMN riboswitch deletion; (iii) Competitive flux minimization by redirecting carbon from acetate formation and catabolic side-reactions; and (iv) Cellular robustness enhancement through NADPH/ATP cofactor balancing and stress tolerance engineering. Complementary bioreactor parameter control including defined media formulations, temperature profiling, and dynamic pH/dissolved oxygen regulation has proven critical for translating laboratory-scale genetic improvements to high-titer production. Recent advances in CRISPR-based genome editing, multi-omics-guided pathway optimization, and antibiotic-free plasmid stabilization demonstrate E. coli's growing viability as a sustainable RF cell factory, with future progress hinging on integrated systems metabolic engineering approaches.