HPLC-ICP-MS speciation of selenium in Se-cultivated Flammulina velutipes

Selenium is an essential micronutrient required at trace levels for human health, and dietary intake is the only source of selenium, which appears mainly in the form of selenocompounds. In this study, Flammulina velutipes was grown for 80 days in standard medium containing selenite, and the level of total selenium in the organism was then determined by inductively-coupled plasma mass spectrometry (ICP-MS). In Se-cultivated F. velutipes, selenium was mainly distributed in the water-soluble form and the content of soluble selenium-containing species in Se-cultivated F. velutipes was 47.10 mg kg^?1, accounted for 72.5% of the total selenium content. The water-soluble proteins in F. velutipes were extracted and precipitated by different ammonium sulfate saturation concentrations. Size-exclusion high performance liquid chromatography (SEC-HPLC) analysis of these proteins revealed the presence of at least six selenium-containing protein species, with molecular weights ranging from 9000 to 74,000 Da, Selenium-containing proteins represented about 7.0% of the total soluble selenium. The result of this study suggested that Se-cultivated F. velutipes could potentially be considered as a selenium supplement for human.