The potency of Monascus purpureus to achieve the transformation from inorganic selenium into organic selenium during the fermentation process

Selenium (Se), as an essential element for the human body, cannot be produced by itself, making Se-rich products research a current hotspot. Microorganisms are common Se-rich carriers and previous experiments mainly focused on yeast and lactic acid bacteria, lacking mold. In this study, the total Se and organic Se content in Monascus purpureus (M. purpureus) were determined by a liquid chromatography-atomic fluorescence spectrometry after fermentation, applying inorganic sodium selenite as exogenous Se. The research results indicated that M. purpureus successfully converted inorganic Se into organic Se, with an organic Se to total Se ratio of 30.50%, 36.14%, 39.94%, 46.18%, and 53.00% at 2, 4, 6, 8, and 10 mg/L sodium selenite, respectively. The proportion of Se-protein (28.04%-47.33%) was highest in organic Se, especially water-soluble Se-protein, followed by Se-polysaccharide (3.80%-5.07%) and Se-nucleic acid (1.84%-3.07%). Furthermore, Se-enriched treatment did not significantly alter the morphology or structure of M. purpureus, while enriching the types and content of volatile components in the fermentation broth. Thus, this study was expected to lay the foundation for the development and utilization of Se-rich M. purpureus products.