Assessment of speciation and in vitro bioaccessibility of selenium in Se-enriched Pleurotus ostreatus and potential health risks

Authors: ZHOU, FEI - Northwest Agricultural & Forestry University; DINH, QUANG - Northwest Agricultural & Forestry University; YANG, WENXIAO - Northwest Agricultural & Forestry University; XUE, MINGYUE - Northwest Agricultural & Forestry University; Banuelos, Gary; LIANG, DONGLI - Northwest Agricultural & Forestry University

Submitted to: Ecotoxicology and Environmental Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2019
Publication Date: 9/16/2019
Citation: Zhou, F., Dinh, Q.T., Yang, W., Xue, M., Banuelos, G.S., Liang, D. 2019. Assessment of speciation and in vitro bioaccessibility of selenium in Se-enriched Pleurotus ostreatus and potential health risks. Ecotoxicology and Environmental Safety. https://doi.org/10.1016/j.ecoenv.2019.109675.
DOI: https://doi.org/10.1016/j.ecoenv.2019.109675

Interpretive Summary: Selenium (Se) is essential for mammals and has many critical biological functions. To enhance Se intake in Se-deficient humans, Se has been applied to planted soils to produce Se-enriched food products. The question remains as to which form of Se is most efficient for increasing Se content and bioaccessible Se in the edible product. In this study, inorganic and organic forms of Se were sprayed at different application rates onto growing substrate used for cultivating mushroom. After 45-70 days, the total Se content and speciation of Se in mushroom fruit bodies were analyzed, and the bioaccessible Se was determined via a simulated gastrointestinal digestion test. Results showed that mushroom accumulated the greatest amount of Se with application of selenite, followed by Se yeast (selenomethionine), and then selenate. In the mushroom, organic forms of Se were the major species of Se identified with all Se treatments. Importantly, the bioaccessible Se was high for all Se treatments. Thus, Se-enriched mushrooms can be produced with application of Se, and the mushroom can be considered as a dietary source of Se for increasing Se intake in Se-deficient regions throughout the world.

Technical Abstract: Selenium (Se) is an essential micronutrient for mammals. It is an important component of the antioxidant defense system and thyroid hormone metabolism process. In many parts of the world, e.g., China, hundreds of millions of the population are Se-deficient. In such areas, enriching crops with Se via biofortification strategies is a safe and efficient way to increase Se intake of residents. In this biofortification study, Na2SeO4, Na2SeO3, and Se yeast (selenomethionine) were selected as Se sources to be used for growing Se-enriched mushrooms. Each source of Se was respectively sprayed into the substrate for growing mushroom (P. ostreatus) at different application rates (i.e., 0.1, 0.5, 1.0, 2.5, and 5.0 mg of Se per kilogram of fresh weight of substrate). After 45 and 70 days of growth, the mushrooms were harvested and the total content, speciation, and bioaccessibility of Se were determined in the Se-enriched P. ostreatus fruit bodies. The total Se concentrations in fruit bodies of P. ostreatus treated with no Se (control), Na2SeO3, Na2SeO4, and Se yeast increased with increasing rate of Se application, irrespective of form applied. Concentrations ranged from low to high as follows for the three different forms and concentrations of Se applied: 1.14–48.50 (selenite), 1.20–32.04 mg/kg DW (selenomethonine), and 0.97–18.18 (selenate), respectively. Organic forms of Se (more than 50% as selenomethionine) were the major species of Se identified in the mushrooms. With all three sources of Se, the bioaccessibility of Se ranged from 70%–92% in the gastrointestinal digestion test fractions of the selected samples. Both Se concentrations and Se biaoccessibility were significantly enhanced in the fruit bodies of P. ostreatus with increased application concentration of Se (p<0.05). The Se-enriched P. ostreatus with enhanced total Se content and bioaccessible Se may be an ideal dietary Se source for increasing daily intake of Se in humans with normal human consumption. Further studies are needed for evaluating risk assessment of such Se-enriched products.