Selenium biofortification ofPleurotusspecies and its effect on yield, phytochemical profiles, and protein chemistry of fruiting bodies

Abstract

Selenium is considered an essential component of a balanced diet due to its antioncogenic and antioxidative properties. Highly popular edible mushrooms belonging to the genus Pleurotus (Oyster mushrooms) were biologically fortified with selenium by exploiting their saprophytic ability. Selenium-rich wheat straw, generally wasted or burned by farmers, was used for cultivation of three species of Pleurotus: P. florida, P. ostreatus, and P. sajor-caju. Atomic Absorption Spectroscopy of harvested fruiting bodies exhibited over a 100-fold increase in bio-accumulation of selenium compared to control samples. P. florida preferred selenium-rich substrate over the normal straw as exhibited by increased yield on selenium-rich straw. Total protein content and antioxidant profiles of Se-rich mushroom extracts also improved significantly. Vibrational Infra-Red Spectroscopy analysis confirmed alteration of flexibility and unfolding of proteins extracted from Se-rich fruit bodies compared to the control, indicating bond formations between selenium and amino acids. The extracts and proteins from selenium enriched as well as control Pleurotus species also showed inhibitory potential towards common pathogens. Practical applications The Se-rich wheat straw can be a useful though underutilized substrate for cultivation of Se-biofortified oyster mushrooms besides enhancing their protein content. The oyster mushrooms cultivated on Se-rich wheat straw vary in their Se-accumulation potentials. Thus, greater health benefits can be obtained by choosing specific Se-rich oyster mushroom species. The Se-proline can be one of the alternate Se-species besides Se-cysteine and Se-methionine. Se-biofortification of oyster mushrooms is feasible by cultivation on Se-rich agricultural waste such as wheat straw which otherwise is burnt by the farmers resulting in air pollution.