Speciation of selenium in pleurotus ostreatus and lentinula edodes Mushrooms

Abstract

Pleurotus ostreatus and Lentinula edodes are two of the most commercialized mushrooms species in the world and exhibit the potential to accumulate selenium (Se). The form of Se in the protein extracts of P. ostreatus and L. edodes mushrooms enriched with Se has been investigated with the aim of obtaining a protein extract with high concentrations of selenomethionine (SeMet). For an approach to the speciation of Se incorporated in P. ostreatus proteins, size exclusion high performance liquid chromatography was used in combination with inductively coupled plasma mass spectrometry (SEC-HPLC-ICP-MS) and two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Se-enriched mushrooms of P. ostreatus and L. edodes were used. The proteins were extracted with phosphate buffer, borate buffer and solubili-zation buffer (2DE) and were purified by acetone precipitation. The extracts were analyzed by reversed phase high performance liquid chro-matography in combination with inductively coupled plasma mass spectrometry (RP-HPLC-ICP-MS). The efficiency of the extraction of Se compounds varied according to the buffer type and the species of fungus. The 2DE buffer was the most efficient, reaching a recovery of 60% and 30% of all Se in the protein extracts of to P. ostreatus and L. edodes, respectively. The main form of Se in the protein extracts was Se-Met. The Se concentration was higher in P. ostreatus than in L. edodes. The P. ostreatus protein extracts with 2DE buffer represent a great potential for obtaining biomass proteins with high SeMet concentrations on an industrial scale. The 2D-PAGE analyses revealed the presence of eight Se-containing proteins. The nutritional value of protein biomass containing SeMet presently has a high potential to be explored by pharmaceutical industries.