Biosynthesis of Se-methyl-seleno-l-cysteine in Basidiomycetes fungus Lentinula edodes (Berk.) Pegler

BACKGROUND The aim of the current study was to investigate whether the Basidiomycetes fungus Lentinula edodes can biosynthesize Se-methyl-seleno-l-cysteine, a seleno-amino acid with strong anticancer activity, and to optimize the culture conditions for its biosynthesis. We hypothesize that preparations obtained from Se-methyl-seleno-l-cysteine-enriched mycelia from this medicinal mushroom would possess stronger cancer-preventive properties than current preparations. RESULTS By optimizing the concentration of selenium in the culture medium, we increased the mycelial concentration of Se-methyl-seleno-l-cysteine from essentially non-detectable levels to 120 µg/g dry weight. Significantly elevated levels of this amino acid also correlated with significant (twofold) inhibition of mycelial growth. Increases in the concentration of mycelial Se-methyl-seleno-l-cysteine appeared to be highly correlated with the enhanced biosynthesis of selenomethionine and total selenium content in mycelium. CONCLUSIONS We have demonstrated that in L. edodes, enhanced biosynthesis of this non-protein amino acid eliminates excess selenium.