Enhanced gibberellic acid production in Fusarium fujikuroi through ARTP-EMS mutagenesis and fermentation optimization

Gibberellic acid (GA₃) is an important plant growth regulator with rising agricultural demand, yet its industrial production via submerged fermentation using Fusarium fujikuroi remains limited by low space-time yield. In this study, a high-yield mutant was generated through atmospheric and room-temperature plasma (ARTP) and ethyl methanesulfonate (EMS) mutagenesis, coupled with lovastatin-based screening. Process optimization, including early nitrogen supplementation, late-stage pH control, and a two-stage temperature-agitation strategy, further enhanced GA₃ synthesis. The mutant (strain 9) achieved a GA₃ titer of 2.483 g/L in a 5-L bioreactor, a 33.38% increase over the parent strain. Additionally, solid-state fermentation using wheat bran as substrate and 60% (w/w) initial moisture yielded 6.5 g/kg dry substrate. These results demonstrate an effective approach for strain improvement and fermentation optimization, providing a foundation for industrial-scale GA₃ production by F. fujikuroi.