Insight into selenium biofortification and selenite metabolic mechanism of Monascus ruber through physicochemical characterization and transcriptome analysis

Monascus spp., edible filamentous fungi, possess great potential for selenium (Se) supplementation. Here, the effects of Se bio-fortification on the growth, morphology, and biosynthesis of Monascus ruber M7 were investigated. Notably, the yield of orange and red Monascus pigments (MPs) in red yeast rice (RYR) increased by approximately 38.52% and 36.57%, respectively, under 20 μg/mL of selenite pressure. Meanwhile, citrinin (CIT), a mycotoxin, decreased from 244.47 μg/g to 175.01 μg/g. Transcriptome analysis revealed that twelve genes involved in MPs biosynthesis, specifically MpigN, MpigF, and MpigE, were significantly upregulated. Three genes involved in CIT biosynthesis were significantly downregulated. Moreover, metG (Log2FC = 1.8) and metH (Log2FC = 2.2) of the selenocompound metabolic pathway were significantly up-regulated, which may help accelerate the synthesis of methyl-selenol (CH3SeH). These findings provide insights into the mechanism of selenite metabolism in filamentous fungi, revealing a potential application for Monascus ruber in Se supplementation and functional foods.