Studies on biofortification of selenium in edible mushrooms

Abstract

Seven edible mushroom strains namely Agaricus bisporus (U-3) and Volvariella volvacea(Vv-4) and five strains of Pleurotus, viz. Pleurotus florida (DMRP-136), Pleurotus djamor (DMRP-205), Pleurotus sajorkaju (DMRP-112), Pleurotus citrinopileatus (DMRP-10) and Pleurotus ostreatus (DMRP-2) were cultivated on agricultural residues belonging to selenium rich and non enriched sites. All Se-rich strains were found to accumulate significantly high selenium content than respective non-Se strains, wherein Se-rich P. djamor (145.4 µg Se/gDW) was found to accumulate relatively higher total selenium content than other mushroom species and Se-rich P. citrinopileatus (26.1 µg Se/gDW) accumulated the lowest. Total soluble form of selenium in gastrointestinal extracts (GI) of P. florida as analysed by ICP-DRC-MS was found to be 105.8 ± 1.6 and#956;g/g dw, which provided an indication that 75% of selenium was appreciably bioavailable to the body. Investigation of the Se molecular fractions revealed that proteins and other high molecular weight selenium-containing molecule were hydrolyzed to peptides and low molecular weight selenocompounds (and#8804;5 kDa based on column calibration). Se speciation in the GI was dominated by selenomethioneine, which represented 73% of the sum of the detected species. Only 2% of the detected species was present as inorganic Se in the form of Se (IV). A number of other low molecular weight selenocompounds generated during the gastrointestinal digestion, accounting for 25% of the chromatographed Se, remained unidentified. Mushrooms cultivated on naturally Se-enriched substrates did not differ from controls in terms of yield and biological efficiency. Mushroom cultivated on Se-rich agricultural residues were examined for their elemental content with respect to their control.