Enhanced production of phomapyrrolidone a through culture-condition optimization and morphological regulation in Didymella sp. FATR0054

Phomapyrrolidone A (Ppd A) is a hirsutellone-type macrocyclic alkaloid derived from marine fungi, exhibiting significant activity against triple-negative breast cancer (TNBC). However, its low fermentation yield has limited further drug development. This study established a systematic optimization strategy integrating medium optimization, mycelial morphology regulation, and computational fluid dynamics (CFD) to enhance Ppd A production by the marine-derived filamentous fungus Didymella sp. FATR0054. Medium composition and fermentation parameters were optimized, increasing shake-flask production from 4.52 mg/L to 289.36 mg/L. The process was successfully scaled up in a 5-L bioreactor. Exogenous co-supplementation further increased production by 26% to 365 mg/L. Morphological regulation proved critical for productivity. Mechanical pre-grinding of the seed culture reduced mycelial pellet diameter to approximately 1 mm, creating compact and uniform pellets. This increased Ppd A production to 389.25 mg/L, representing an 86-fold improvement. CFD analysis of the interactions among the flow field, fungal pellet diameter distribution, and product formation identified 450 rpm as a candidate operating compromise for the current 5-L bioreactor, based on the simulated spatial uniformity of the Ppd A concentration field, local energy dissipation, and pellet fragmentation. This study establishes an integrated fermentation intensification strategy combining experimental optimization and flow-field modeling for large-scale production of Ppd A and process regulation in filamentous fungal fermentation.