The role of selenium speciation in the antagonism of selenium and toxic metals in selenium enriched mushrooms

Abstract

The consumption of edible mushrooms is a nutritional resource currently not fully utilized, that has the potential to increase the nutritional quality of large populations at marginal cost. Due to the possible presence of selenium (Se) in their composition and being bioaccumulators of metals and metalloids, the mushrooms have been the object of studies aimed at the Se enrichment for human consumption. Mushrooms are also of interest in research involving bioremediation due to the high capacity to accumulate toxic elements while cleaning their growing subtract. Additionally, Se can remediate the contamination of mushrooms with heavy metals by promoting a decrease in absorption or elimination of toxic elements, such as Hg and Cd. These observations so far are encouraging to present mushrooms as an interesting and useful food to be added to a healthy diet. However, the molecular and metabolic aspects of the antagonism between the different Se species with toxic metals, as well as the species formed after enrichment or remediation, lack the required level of knowledge, especially about elemental chemical speciation, before safe human consumption is recommended. Thus, this project aims to carry out chemical speciation studies of Se to evaluate the metabolism and bio-transformations of different Se species in white (Pleurotus ostreatus) and pink oyster mushrooms (Pleurotus djamor). This characterization of the selenium metabolism will assist in understanding the synergistic relationship between Se and toxic elements and the protective role of Se against cadmium (Cd), mercury (Hg) and lead (Pb) toxicity. For this, liquid chromatography coupled to inductively coupled plasma mass spectrometry (LC-ICP-MS) as separation and detection methods will be developed, validated and implemented. For this multiple extraction, methods will be developed and/or adapted for identification of Se species, such as common "seleno-amino acids" and inorganic Se species. The total content of selenium and different chemical forms of selenium will be monitored, as a means to evaluate the effectiveness of Se-enrichment of edible mushrooms with Se(IV) and Se(VI) added to the culture medium from a nutritional point of view, and bioconversion of Se species in the protective effect against toxic elements for environmental bioremediation purposes.