Efficacy of supplementation of selected medicinal mushrooms with inorganic selenium salts

Effect of Selenium-Enriched Substrate on the Chemical Composition, Mineral Bioavailability, and Yield of Edible Mushrooms

Mushrooms absorb minerals from substrates in which they are cultivated, so they could be used as vehicles of minerals that are deficient in human or animal diets, such as selenium. Selenium deficiency aggravates cardiovascular diseases, diabetes mellitus, and intestinal cancer. This work presents the latest discoveries related to the production of edible mushrooms in selenium-enriched substrates and discusses their use as an alternative to supply the deficiency of this mineral in human and animal diets. Selenized mushrooms and their derived extracts present bioaccessible and bioavailable forms of selenium, as antioxidant and antitumor activity, as demonstrated in various in vitro and in vivo experiments. Consequently, the consumption of these mushrooms reduces the levels of blood cholesterol and glucose. On the other hand, growing mushrooms in selenium-enriched substrates may alter the yield and their chemical composition, and this lack of standardization is still an obstacle to the scale up of the production process. On the other hand, the use of agro-industrial by-products as substrates can enable the cultivation of enriched edible mushrooms and their commercialization.

Enrichment of Culinary-Medicinal Oyster Mushroom, Pleurotus ostreatus (Agaricomycetes), Cultivated on the Straw Substrate with Zinc and Selenium

Pleurotus ostreatus was cultivated on a commercially available wheat straw substrate enriched with Zn and Se. Various amounts of Zn (10, 50, and 100 mg) and Se (1, 5, and 10 mg) in suitable forms ((CH3COO)2Zn·2H2O, Zn(NO3)2·6H2O, and Na2SeO3·5H2O, respectively) were dissolved in 50 ml of deionized water and homogenously nebulized into the substrate block of 2.4 kg weight. The increase in the Zn content in fruiting bodies cultivated on the enriched substrate was relatively low compared with fruiting bodies cultivated on the substrate with no addition at the first flush. The application of different Zn compounds (acetate vs. nitrate) gave similar results. However, the addition of 1 mg of Se into the cultivation substrate block increased the content of Se in fruiting bodies to about 3-6 mg/kg dry matter. This content was one order of magnitude higher compared with the Se content in fruiting bodies harvested from the substrate with no Se addition (< 0.12-0.58 mg/kg dry matter). In the case of the addition of 5 mg of Se, there was a further significant increase in the content of this element to about 40-60 mg/kg dry matter.

Influence of selenium on the mycelia of the shaggy bracket fungus, Inonotus hispidus

BACKGROUND

Selenium (Se) is a needed trace element for animals and humans. Many fungi have effective mechanisms to acquire, transform and accumulate Se in organic form. In this study, the effects of inorganic Se (sodium selenite) on the medicinal fungus Inonotus hispidus was investigated.

RESULTS

Inonotus hispidus was capable of tolerating up to 3.85 mmol L^-1 selenite, at which ~85% growth inhibition was seen, with 50% growth inhibition occurring at ~1 mmol L^-1 selenite. Growth in 0.29 mmol L^-1 Se resulted in I. hispidus mycelium with 115 times higher Se levels compared to growth in standard media, and an organic Se content of 86% to total Se content. The influence of Se accumulation on morphological features of I. hispidus were examined by microscopic and scanning electron microscopic observation. These data revealed significant shrinkage and deformations of I. hispidus hyphae with decreased branching and collapse of clamp connections under higher Se stress. However, conidial production in I. hispidus increased dramatically. The influence of Se on mycelial growth could be recovered by reinoculation in standard media. Se accumulation had only minimal impacts on the yield of the potential selenocompounds such as amino acids, proteins and polysaccharides. By contrast, Se-enriched I. hispidus mycelium was of higher quality due to reduction in crude fat and total ash contents.

CONCLUSIONS

These data provide basic and applied information on the feasibility of producing selenized I. hispidus as an enriched and better quality product. © 2021 Society of Chemical Industry.

Biofortification of Three Cultivated Mushroom Species with Three Iron Salts—Potential for a New Iron-Rich Superfood

Mushrooms fortified with iron (Fe) can offer a promising alternative to counter the worldwide deficiency problem. However, the factors that may influence the efficiency of fortification have not yet been fully investigated. The aim of this study was to compare the effects of three Fe forms (FeCl₃ 6H₂O, FeSO₄ 7H₂O, or FeHBED) in three concentrations (5, 10, or 50 mM) for three mushroom species (Pleurotus eryngii, P. ostreatus, or Pholiota nameko) on their chemical composition, phenolic compounds, and organic acid production. The most effective metal accumulation of all the investigated species was for the 50 mM addition. FeCl₃ 6H₂O was the most favorable additive for P. eryngii and P. nameko (up to 145 and 185% Fe more than in the control, respectively) and FeHBED for P. ostreatus (up to 108% Fe more than in control). Additionally, P. nameko showed the highest Fe accumulation among studied species (89.2 ± 7.51 mg kg⁻¹ DW). The creation of phenolic acids was generally inhibited by Fe salt supplementation. However, an increasing effect on phenolic acid concentration was observed for P. ostreatus cultivated at 5 mM FeCl₃ 6H₂O and for P. eryngii cultivated at 5 mM FeCl₃ 6H₂O and 5 mM FeSO₄ 7H₂O. In the case of organic acids, a similar situation was observed. For P. ostreatus, FeSO₄ 7H₂O and FeHBED salts increased the formation of the determined organic acids in fruiting bodies. P. eryngii and P. nameko were characterized by a much lower content of organic acids in the systems supplemented with Fe. Based on the obtained results, we recommend starting fortification by preliminarily indicating which form of the element is preferred for the species of interest for supplementation. It also seems that using an additive concentration of 50 mM or higher is most effective.

The protective role of selenium against uptake and accumulation of cadmium and lead in white oyster (Pleurotus ostreatus) and pink oyster (Pleurotus djamor) mushrooms

Mushrooms are bioaccumulators and have been used to produce Se-enriched foods. However, these fungi can also bioaccumulate potentially toxic metals, producing food dangerous to human health. It is known that co-exposure to Se plays a protective role against metal accumulation and toxicity in some organisms due to its antioxidant properties. Thus, this study aimed to evaluate the protective effect of Se(IV) and Se(VI) on elemental uptake and accumulation as well as proteins and protein-bound Se, Cd, and Pb distribution in Pleurotus mushrooms. Pink oyster and white oyster mushrooms showed high ability to bioaccumulate Se (19-205 µg g^-1), Cd (4.5 to 18.8 µg g^-1), and Pb (1.6 to 7.0 µg g^-1). Growth substrate supplementation with Se(IV) or Se(VI) decreased the Cd total concentration in mushrooms by 4 to 89%, while Se(VI) increased the Pb total concentration by 9% to 187%, compared to growth in absence of Se. It was found that despite molecular weights distributions of mushrooms grown on Se(IV) and Se(VI)-supplemented substrates being similar, Se(VI) supplementation favoured Se interaction with proteins of medium molecular weight (17-44 kDa), when compared to supplementation with Se(IV). Therefore, we propose the supplementation of growth substrates with Se(VI) to reduce eventual Cd accumulation and produce Se-enriched oyster mushrooms.

Polymer Nanocomposites of Selenium Biofabricated Using Fungi

Nanoparticle-reinforced polymer-based materials effectively combine the functional properties of polymers and unique characteristic features of NPs. Biopolymers have attained great attention, with perspective multifunctional and high-performance nanocomposites exhibiting a low environmental impact with unique properties, being abundantly available, renewable, and eco-friendly. Nanocomposites of biopolymers are termed green biocomposites. Different biocomposites are reported with numerous inorganic nanofillers, which include selenium. Selenium is a micronutrient that can potentially be used in the prevention and treatment of diseases and has been extensively studied for its biological activity. SeNPs have attracted increasing attention due to their high bioavailability, low toxicity, and novel therapeutic properties. One of the best routes to take advantage of SeNPs' properties is by mixing these NPs with polymers to obtain nanocomposites with functionalities associated with the NPs together with the main characteristics of the polymer matrix. These nanocomposite materials have markedly improved properties achieved at low SeNP concentrations. Composites based on polysaccharides, including fungal beta-glucans, are bioactive, biocompatible, biodegradable, and have exhibited an innovative potential. Mushrooms meet certain obvious requirements for the green entity applied to the SeNP manufacturing. Fungal-matrixed selenium nanoparticles are a new promising biocomposite material. This review aims to give a summary of what is known by now about the mycosynthesized selenium polymeric nanocomposites with the impact on fungal-assisted manufactured ones, the mechanisms of the involved processes at the chemical reaction level, and problems and challenges posed in this area.

Changes in mineral composition of six strains of Pleurotus after substrate modifications with different share of nitrogen forms

The chemical characteristics of substrate are one the most significant factors influencing the growth and development of cultivated mushroom species. The aim of this study was to determine the mineral composition of six Pleurotus species (P. cistidiosus, P. djamor, P. ostreatus, P. ostreatus var. florida, P. pulmonarius and P. sajor-caju) growing on three wheat straw substrates with the addition of agricultural fertilizer rich in ammonium and with addition of salt solution rich in nitrates. Significant differences in the concentration of Al, Ca, Cu, Ir, Ni, Ru, Sn and Te were observed in all substrates used in this experiment. Cultivation on chemically-enriched substrates did not result in changes in yield with the exception of P. sajor-caju, which had a lower yield when grown on ammonium-rich substrate. No macroscopic alterations in fruit bodies were observed for any species regardless of the applied substrate. A higher concentration of selected elements was not correlated with their higher content in particular mushroom species, or such a relationship was present only in selected mushroom species. The efficiency of element accumulation depends on their concentration in the substrate (positive values of rs), although the mushroom species and the nitrogen form concentration may also have a significant impact (negative rs values). The obtained results show that cultivation of different Pleurotus strains on substrates enriched with a different share of ammonium and nitrate may cause changes in their mineral composition in spite of the similarity in the concentration of the majority elements in substrates.

Mineral Composition of Three Popular Wild Mushrooms from Poland

The region of Warmia and Mazury is characterized by the special diversity and richness of its natural environment, including large forest complexes, where wild mushrooms are commonly collected and consumed. This study aimed to examine the differences in mineral content (calcium, magnesium, sodium, potassium, iron, zinc, copper, manganese) of three species of mushrooms collected in north-eastern Poland. The research material consisted of dried samples of king bolete (Boletus edulis), bay bolete (Boletus badius), and chanterelle (Cantharellus cibarius) collected in the region of Warmia and Mazury. The content of the above-mentioned elements in mushroom fruit bodies was determined using the flame atomic absorption spectrometry (acetylene-air flame) and the emission technique (acetylene-air flame) for sodium and potassium. For the majority of micro- and macroelements, the studies confirmed the presence of significant differences in their content, depending on the species of fungi. The studied mushrooms cover a significant percentage of daily demand for many of the minerals. This concerns mainly copper, zinc, and potassium, although none of the species was a good source of calcium and sodium. Among the analyzed mushrooms, chanterelle is the best source of most minerals.

Selenium biofortification in Hericium erinaceus (Lion's Mane mushroom) and its in vitro bioaccessibility

Hericium erinaceus is a traditional edible mushroom. Selenium (Se) is an essential trace element for humans and other mammals. To develop a Se biofortification strategy for H. erinaceus, the effects of selenate, selenite, and selenomethionine (SeMet) on Se uptake and mushroom growth were investigated. Selenium bioaccessibility and the major Se species present in Se-enriched H. erinaceus were tested in vitro . The H. erinaceus growth was efficiently affected by SeMet than by selenite and selenate. Selenium concentrations in fruiting bodies increased with substrate Se concentration and disturbed accumulation of other microelements. Substrate Se was absorbed and transformed into organic forms. The major Se species in Se-enriched fruiting bodies was SeMet (>63.9%). During in vitro gastrointestinal digestion tests, 51% of total Se was released, and selenocystine (SeCys₂ ) (90%) and Se-methylselenocysteine (MeSeCys) (76%) were more easily digested than SeMet (51%). H. erinaceus is suggested as a novel dietary source of supplemental bioavailable Se.

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

Due to the two-dimensional effect of selenium (Se) to health, which form of Se is most effective for increasing the bioaccessible Se content in P. ostreatus and whether these products have potential health risks are worth considering. Three Se supplements were applied at different application rates into substrates for cultivating P. ostreatus. The total content and speciation of Se in P. ostreatus fruit bodies were analyzed, and the bioaccessibility of Se was determined via an in vitro physiologically based extraction test (PBET). Results showed that P. ostreatus had the highest utilization efficiency with selenite, followed by Se yeast and selenate. Organic Se (46%-90%) was the major Se speciation in P. ostreatus regardless applied Se species. Although the Se bioaccessibility of the gastrointestinal digestion of P. ostreatus was high (70%-92%), the estimated daily intake and target hazard quotient values are all within the safe ranges. Se-enriched P. ostreatus can be safely used as a dietary source of Se for increasing Se intake.

Transcriptional profiling of Auricularia cornea in selenium accumulation

Auricularia cornea is a widely cultivated edible fungus with substantial nutritive value. This study aimed to enrich the multifunctional bionutrient element selenium in A. cornea to improve its quality and explore the accumulation of selenium in the fungus using high-throughput RNA-Seq technology. In general, the treatment group with a 100 µg/g supply of selenium outperformed the other treatment groups in terms of high yield, rich crude polysaccharides and a high total selenium concentration. Additional evidences demonstrated the budding and mature phases were two typical growth stages of A. cornea and were important for the accumulation of selenium. Therefore, the budding and mature phase tissues of A. cornea in the treatment group with a 100 µg/g supply of selenium were used for transcriptome analysis and compared to those of a control group that lacked additional selenium. A total of 2.56 × 105 unigenes from A. cornea transcriptome were assembled and annotated to five frequently used databases including NR, GO, KEGG, eggNOG and SwissProt. GO and KEGG pathway analysis revealed that genes involved in metabolic process and translation were up-expressed at the budding stage in response to selenium supplementation, including amino acid metabolism, lipid metabolism, ribosome. In addition, the differential gene expression patterns of A. cornea suggested that the up-expressed genes were more likely to be detected at the budding stage than at the mature stage. These results provide insights into the transcriptional response of A. cornea to selenium accumulation.

Arsenic and Other Elemental Concentrations in Mushrooms from Bangladesh: Health Risks

Mushroom cultivation has been increasing rapidly in Bangladesh. Arsenic (As) toxicity is widespread in the world and Bangladesh faces the greatest havoc due to this calamity. Rice is the staple food in Bangladesh and among all the crops grown, it is considered to be the main cause of As poisoning to its population after drinking water. Consequently, rice straw, an important growing medium of mushrooms in Bangladesh, is known to have high As content. The objective of this study was, therefore, to determine the concentrations of As in mushrooms cultivated in Bangladesh and to assess the health risk as well. It also considered other elements, including Cd, Cr, Co, Cu, Pb, Mn, Hg, Ni, and Zn concentrations in mushrooms from Bangladesh. The mean concentrations (mg/kg) of As, Cd, Cr, Co, Cu, Pb, Mn, Hg, Ni, and Zn in mushrooms were 0.51, 0.38, 0.28, 0.01, 13.7, 0.31, 11.7, 0.12, 0.28, and 53.5, respectively. Based on the dietary intake of mushrooms, the weekly intakes of As, Cd, Cr, Co, Cu, Pb, Mn, Hg, Ni, and Zn from mushrooms for adults were 0.0042, 0.0030, 0.0024, 0.0001, 0.1125, 0.0019, 0.1116, 0.0011, 0.0023, and 0.4734 mg, respectively. Due to the low concentrations of As and other trace elements observed in mushrooms from Bangladesh, as well as relatively lower consumption of this food in people’s diet, it can be inferred that consumption of the species of mushrooms analysed will cause no toxicological risk.

Multi-elemental analysis of Lentinula edodes mushrooms available in trade

The present study investigated the content of 62 elements in the fruiting bodies of Lentinula edodes (Shiitake mushroom) cultivated commercially in Poland on various substrates from 2007-2015. The general mean content (mg kg^-1 dry weight (DW)) of the studied elements ranked in the following order: K (26,335) > P (11,015) > Mg (2,284) > Ca (607) > Na (131) > Zn (112) > Fe (69) > Mn (33) > B (32) > Rb (17) > Cu (14.5) > Al (11.2) > Te (2.9) > As (1.80) > Cd (1.76) > Ag (1.73) > Nd (1.70) > Sr (1.46) > Se (1.41) > U (1.11) > Pt (0.90) > Ce (0.80) > Ba (0.61) > Co (0.59) > Tl (0.58) > Er (0.50) > Pb (0.42) > Li (0.40) > Pr (0.39) > Ir (0.37) > In (0.35) > Mo (0.31) > Cr (0.29) > Ni (0.28) > Sb (0.26) > Re (0.24) > Ti (0.19) > Bi (0.18) > Th (0.12) > La (0.10) = Pd (0.10) > Os (0.09) = Zr (0.09) > Rh (0.08) > Ho (0.07) > Ru (0.06) > Sm (0.04) = Eu (0.04) = Tm (0.04) > Gd (0.03) > Sc (0.02) = Y (0.02) > Lu (0.01) = Yb (0.01) = V (0.01). The contents of Au, Be, Dy, Ga, Ge, Hf, and Tb were below the limits of detection (0.02, 0.02, 0.01, 0.01, 0.01, 0.01, 0.02 mg kg^-1 respectively). The concentrations of Al, As, B, Ba, Ca, Cd, Cr, Er, Fe, In, Lu, Mn, Nd, Sr, Ti, Tm, and Zr were comparable over the period the mushrooms were cultivated. The study revealed that Lentinula edodes contained As and Cd at levels potentially adverse to human health. This highlights the need to monitor these elements in food products obtained from this mushroom species and ensure that only low levels of these elements are present in cultivation substrates.

Cultivation of Agaricus bisporus enriched with selenium, zinc and copper

BACKGROUND

Agaricus bisporus (white button mushroom) is an important culinary and medicinal species of worldwide importance. The present study investigated for the first time whether it may be grown on substrates supplemented with Se alone or in combination with Cu and/or Zn (0.1-0.8 mmol L^-1 ) to produce fruiting bodies of increased nutritional value.

RESULTS

As found, substrate supplementation did not affect yielded biomass up to 0.6 mmol L^-1 element concentrations regardless of the cultivation model. At 0.8 mmol L^-1 Se + Cu and Se + Zn supplementation biomass comparable with controls still developed. The accumulation of trace elements in the fruiting bodies generally increased over the concentration gradient reaching its maximum at 0.6 mmol L^-1 (for Se + Zn and Se + Cu + Zn) and 0.8 mmol L^-1 (for Se and Se + Cu). The organic Se constituted the greatest share in total Se quota. As calculated, each 10 g of dried fruiting bodies of A. bisporus obtained from 0.6 or 0.8 mmol L^-1 supplementation would represent 342-469% of the Recommended Daily Allowance (RDA) for Se, 43.4-48.5% for Cu and 5.2-5.8% for Zn.

CONCLUSION

Considering inexpensive methods of A. bisporus cultivation, global popularity and use of this mushroom, its biofortification with Se, Cu and Zn could have a practical application in deficiency prevention and assisted treatment. © 2016 Society of Chemical Industry.

Bioaccumulation of metals and metalloids in medicinal plant Ipomoea pes-caprae from areas impacted by tsunami

Tsunami events may have an enormous impact on the functioning of aquatic and terrestrial ecosystems by altering various relationships with biotic components. Concentrations of acid-leachable fractions of heavy metals and metalloids in soils and plant samples from areas affected by the December 2004 tsunami in Thailand were determined. Ipomoea pes-caprae, a common plant species growing along the seashore of this region, and frequently used in folk medicine, was selected to assess the presence of selected elements. Elevated amounts of Cd, Pb, Zn, and As in soil samples, and Pb, Zn, As, Se, Cr, and Ni in plant samples were determined from the tsunami-impacted regions for comparison with reference locations. The flowers of Ipomoea pes-caprae contained the highest amounts of these metals, followed by its leaves, and stems. In addition, its bioaccumulation factor (BAF) supports this capability of high metal uptake by Ipomoea pes-caprae from the areas affected by the tsunami in comparison with a reference site. This uptake was followed by the translocation of these elements to the various plant components. The presence of these toxic metals in Ipomoea pes-caprae growing in contaminated soils should be a concern of those who use this plant for medicinal purposes. Further studies on the content of heavy metals and metalloids in this plant in relation to human health concerns are recommended.