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

Summary

This research explored how shiitake mushrooms can produce a cancer-fighting compound called Se-methyl-seleno-L-cysteine when grown with selenium. The findings could lead to more effective natural cancer prevention supplements. Impacts on everyday life: • Could lead to improved cancer-prevention supplements • Demonstrates how common mushrooms can be enhanced for better health benefits • Shows potential for creating safer, natural forms of selenium supplements • Provides new understanding of how mushrooms process minerals for human benefit • Could influence future dietary recommendations for cancer prevention

Background

Selenium is a key nutrient in cancer chemoprevention, with its bioavailability and toxicity depending on its chemical form. Se-methyl-seleno-L-cysteine (MeSeCys) has shown superior efficacy in preventing and treating cancer compared to other selenium compounds. Lentinula edodes (shiitake mushroom) is known for its medicinal properties, particularly its antitumor activity through immune system activation. The researchers hypothesized that enriching L. edodes with organic selenium compounds could enhance its anticancer properties.

Objective

To investigate whether the Basidiomycetes fungus Lentinula edodes can biosynthesize Se-methyl-seleno-L-cysteine and to optimize the culture conditions for its biosynthesis. The researchers aimed to create selenium-enriched mushroom preparations with enhanced cancer-preventive properties.

Results

By optimizing selenium concentration in the culture medium, researchers increased mycelial Se-methyl-seleno-L-cysteine levels from non-detectable to 120 μg/g dry weight. This increase correlated with enhanced selenomethionine biosynthesis and total selenium content. Higher selenium levels (>15 μg/mL) in the medium inhibited mycelial growth, with optimal Se-methyl-seleno-L-cysteine production occurring at 20 μg/mL selenium concentration.

Conclusion

The study demonstrated that L. edodes can biosynthesize Se-methyl-seleno-L-cysteine as a mechanism to eliminate excess selenium. Enhanced biosynthesis of this non-protein amino acid correlated with significant growth inhibition. The findings suggest this could be a detoxification method used by the fungus when exposed to high selenium levels.
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