Enhanced ergothioneine production in Pleurotus tuber-regium through submerged fermentation optimization and selenium-driven mechanistic insights

Ergothioneine (EGT) production in Pleurotus tuber-regium was significantly enhanced through Na 2 SeO 3 -induced oxidative stress, in combination with optimized carbon sources and precursor amino acids. Initially, glucose and rhamnose (20 g/L each) as dual carbon sources increased EGT synthesis. Supplementation with 0.75 mM cysteine and 1 mM methionine further promoted EGT biosynthesis by providing essential precursors. Additionally, the introduction of 0.3 mM Na 2 SeO 3 induced oxidative stress, leading to an EGT accumulation of 4.68 mg/g dry weight (DW) in the mycelium and a yield of 35.27 mg/L, representing a 4.25-fold and 162% increases compared to the control, respectively. RNA-Seq analysis revealed that selenium exposure triggered the upregulation of genes involved in antioxidant defense, reinforcing redox homeostasis and driving EGT accumulation. This study highlights the mechanistic role of selenium in modulating antioxidant pathways, offering a promising strategy for enhancing EGT production in the nutraceutical and biotechnological fields.