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Spent mushroom substrate (SMS) is the residual biomass generated after harvesting the fruitbodies of edible/medicinal fungi. Disposal of SMS, the main by-product of the mushroom cultivation process, often leads to serious environmental problems and is financially demanding. Efficient recycling and valorization of SMS are crucial for the sustainable development of the mushroom industry in the frame of the circular economy principles. The physical properties and chemical composition of SMS are a solid fundament for developing several applications, and recent literature shows an increasing research interest in exploiting that inherent potential. This review provides a thorough outlook on SMS exploitation possibilities and discusses critically recent findings related to specific applications in plant and mushroom cultivation, animal husbandry, and recovery of enzymes and bioactive compounds.

Treatment and disposal of wineries and olive-oil mills waste is usually associated with complex processes, which are often of limited wide-scale applicability. Olive-leaves plus two-phase olive mill waste (OLW) or grape marc plus wheat straw (GMW) were assessed as substrates for the cultivation of the choice edible mushroom Pleurotus citrinopileatus. GMW led to increased mushroom biological efficiency and shorter production cycles. Antioxidant activities, triterpenic acids, free amino acids, lovastatin and ergosterol were significantly higher in fruitbodies from GMW; the latter compound was positively correlated with squalene concentrations in substrates. Glucans, resveratrol and fatty acids content showed minor differences among mushrooms from the three substrates examined, whereas ergothioneine was significantly higher in fruitbodies grown on OLW. High correlations were noted for oleanolic, ursolic and amino acid content in mushrooms and their respective substrates. Moreover, FTIR spectra revealed variations in fruitbodies content in bioactive compounds which were associated with the substrates used., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A variety of bioactive compounds, constituents of edible mushrooms, in particular β-glucans, i.e., a group of β-d-glucose polysaccharides abundant in the fungal cell walls, have been linked to immunomodulating, anticancer and prebiotic activities. The aim of the study was the investigation of the genoprotective effects of edible mushrooms produced by Pleurotus eryngii , Pleurotus ostreatus and Cyclocybe cylindracea (Basidiomycota). Mushrooms from selected strains of the species mentioned above were fermented in vitro using faecal inocula from healthy volunteers. The cytotoxic and anti-genotoxic properties of the fermentation supernatants (FSs) were investigated in Caco-2 human colon adenocarcinoma cells. The FSs were cytotoxic in a dose-dependent manner. Non-cytotoxic concentrations were used for the genotoxicity studies, which revealed that mushrooms' FSs have the ability to protect Caco-2 cells against tert-butyl hydroperoxide ( t -BOOH), a known genotoxic agent. Their global metabolic profiling was assessed by 1 H-NMR spectroscopy. A total of 37 metabolites were identified with the use of two-dimensional (2D) homo- and hetero-nuclear NMR experiments. Multivariate data analysis monitored the metabolic variability of gut microbiota and probed to biomarkers potentially associated with the health-promoting effects of edible mushrooms.

Alterations of gut microbiota are evident during the aging process. Prebiotics may restore the gut microbial balance, with β-glucans emerging as prebiotic candidates. This study aimed to investigate the impact of edible mushrooms rich in β-glucans on the gut microbiota composition and metabolites by using in vitro static batch culture fermentations and fecal inocula from elderly donors (n = 8). Pleurotus ostreatus , P. eryngii , Hericium erinaceus and Cyclocybe cylindracea mushrooms derived from various substrates were examined. Gut microbiota composition (quantitative PCR (qPCR)) and short-chain fatty acids (SCFAs; gas chromatography (GC)) were determined during the 24-h fermentation. P. eryngii induced a strong lactogenic effect, while P. ostreatus and C. cylindracea induced a significant bifidogenic effect ( p for all <0.05). Furthermore, P. eryngii produced on wheat straw and the prebiotic inulin had comparable Prebiotic Indexes, while P. eryngii produced on wheat straw/grape marc significantly increased the levels of tested butyrate producers. P. ostreatus , P. eryngii and C. cylindracea had similar trends in SCFA profile; H. erinaceus mushrooms were more diverse, especially in the production of propionate, butyrate and branched SCFAs. In conclusion, mushrooms rich in β-glucans may exert beneficial in vitro effects in gut microbiota and/or SCFAs production in elderly subjects.

Few data exist about the effect of substrates' elemental content on the respective concentrations in cultivated mushrooms, on the degradation of lignocellulosics or on production parameters. Sixteen elements (14 metals and 2 metalloids) were measured by inductively coupled plasma mass spectrometry (ICP-MS) in Pleurotus ostreatus and Cyclocybe cylindracea mushrooms, and in their seven cultivation substrates composed of various plant-based residues. Results revealed a high variability in elemental concentration among substrates which generally led to significant differences in the respective mushroom contents. High bioconcentration factors (BCFs) were noted for Cd, Cu, Mg and Zn for both species in all substrates. BCF of each element was variously affected by substrates' pH, crude composition, and P and K content. Significant positive correlations were demonstrated for Cu, Fe, Mn and Li concentrations vs. a decrease of cellulose and hemicellulose in P. ostreatus substrates, and vs. mushrooms' biological efficiency. In the case of C. cylindracea , Be, Mg and Mn concentrations were positively correlated with the decrease of hemicellulose in substrates, while a significant positive correlation was also recorded vs. mushroom productivity. Finally, it was found that 15% to 35% of the daily dietary needs in Mg, Se and Zn could be covered by mushroom consumption.

Chlorophyllum accommodates lamellate agaricoid species as well as sequestrate angiocarpic taxa, which do not form a monophyletic lineage within the genus. To clarify phylogenetic affinities and delimit species boundaries among sequestrate representatives of the genus, we analyzed historical and contemporary material from a broad geographic range, encompassing North America, southern Africa, eastern Asia, the Greek and Iberian peninsulas, and the Mediterranean islands of Cyprus and Lesvos. Six sequestrate lineages of Chlorophyllum were identified, which appear to have evolved in at least three independent gasteromycetation events. Multigene analysis of the nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and portions of the nuc 28S rDNA (28S), RNA polymerase II second largest subunit ( rpb2 ), and translation elongation factor 1-α ( tef1 ) genes revealed the presence of a previously undescribed species, introduced here as Chlorophyllum levantinum , sp. nov. Its sister species C. lusitanicum , previously known only from Spain, is shown to have a wider distribution throughout the Mediterranean basin. A South African collection of Secotium gueinzii , a poorly known taxon described in 1840 and seldom appearing in literature since, was also shown to nest within Chlorophyllum . An epitype for this rare species is designated, Secotium becomes a priority synonym of Chlorophyllum , and nomenclatural implications are discussed. The phylogenetic placement of C. arizonicum is confirmed after successful sequencing of the century-old holotype and an undescribed sister lineage of this species detected. Emended descriptions of sections Chlorophyllum, Endoptychorum , and Sphaerospororum are provided to reflect current results, along with updated descriptions and extensive imagery for all known sequestrate taxa of Chlorophyllum .

In Italy, the National Agency for the Evaluation of the University System and Research (ANVUR) carries out a systematic evaluation of the "Third Mission" activities of universities and research bodies. In this perspective, universities already engaged in research on medicinal mushrooms and on their potential applications in the industrial sector set the frame for collaboration with large, well-reputed private companies. In Italy, one of the major problems of mycotherapy is related to lack of certification and the dubious origin/identity of mushroom extracts used by the industry. Hence, products deriving from medicinal mushrooms that are in trade do not often meet the required quality criteria. In this paper, a multipartner collaboration is presented, which aims at the bottom to top development of nutraceutical products from Pleurotus mushrooms in agreement to science-to-business (S2B) marketing.

Six wild edible mushroom species, Agaricus bisporus, A. bitorquis, A. gennadii, Coprinus comatus, Psathyrella candolleana and Volvopluteus gloiocephalus, were collected from the Greater Athens area (Greece), together with their soil substrates (two depth-layers) for studying bioaccumulation of heavy metals in a densely populated urban environment. Total and bioavailable Cr, Cu, Fe, Mn, Ni, Pb and Zn concentrations in soils were assessed along with their respective concentrations in mushrooms, and were evaluated in conjunction with soil properties, including K, P and Na content, CaCO 3 equivalent percentage, mechanical composition, pH and organic matter. In particular, Cu, Pb, Zn and Ni displayed a high variability in their total and bioavailable concentrations measured in the upper soil layer. Relatively high Pb and Ni contents were measured in mushrooms, while Cu, Zn, Fe and Mn concentrations varied considerably. No significant correlations were detected between total concentrations of heavy metals in soils and mushrooms, whereas bioavailable fractions for several metals were significantly correlated with their respective content in A. bisporus, C. comatus, P. candolleana and V. gloiocephalus. K, Na and P concentrations in soils were associated to the content of several metals in fruit-bodies. The effect of soil texture on metals accumulation by mushrooms was species-dependent since high correlations were found for V. gloiocephalus and C. comatus only. Interactions between metals content in fruit-bodies seem to be species-specific except for Ni vs. Fe and Mn vs. Fe, which are positively correlated in all cases. Overaccumulation of metals in fruit-bodies was established only in respect to the bioavailable fractions of Cu, Mn, Zn and Ni in soil. The levels of toxicity for Pb were exceeded in mushrooms of five species, whereas the rest of the heavy metals (with the exception of Cu) were detected at lower contents than their recommended dietary allowances or tolerable upper intake levels., (Copyright © 2019. Published by Elsevier B.V.)

Background: Concentrations of 16 rare earth elements (REEs) and two actinides were determined for the first time both in cultivated mushrooms and in their production substrates by inductively coupled plasma mass spectroscopy. Moreover, the effect of REEs on cultivation parameters and composition of the final product was assessed, together with their potential use for authentication purposes., Results: The concentrations of REEs varied greatly among seven cultivation substrates and correlated with measurements in Cyclocybe cylindracea mushrooms; no such correlation was established in Pleurotus ostreatus. Reduction of hemicellulose, cellulose, and lignin in substrates during P. ostreatus cultivation was positively correlated with REE concentrations, which also affected the production performance depending on the species examined. In all cases, a negative correlation was established between bioconcentration factors (BCF) in mushrooms and REE content in substrates, while the effect of substrate composition on BCF values varied according to the element studied. The estimated daily intake values of REEs through mushroom consumption was at much lower levels than those reported as potentially harmful for human health., Conclusion: The content of REEs in cultivation substrates and in mushrooms revealed that the bioaccumulation of elements differed in each fungus. The nature/origin of substrates seemed to affect the concentration of REEs in mushrooms to a considerable extent. © 2018 Society of Chemical Industry., (© 2018 Society of Chemical Industry.)

Environmentally acceptable disposal of olive cultivation residues (e.g., olive prunings; olive pruning residues (OLPR)) and olive mill wastes is of paramount importance since they are generated in huge quantities within a short time. Moreover, olive mill wastewater (OMW) or sludge-like effluents ("alperujo"; two-phase olive mill waste (TPOMW)) are highly biotoxic. Hericium erinaceus is a white-rot fungus which produces choice edible mushrooms on substrates rich in lignocellulosics, and its suitability for the treatment of olive by-products was examined for the first time. Fungal growth resulted in a notable reduction of OMW's pollution parameters (i.e., 65 % decolorization, 47 % total phenolic reduction, and 52 % phytotoxicity decrease) and correlated with laccase and manganese peroxidase activities. Solid-state fermentation of various mixtures of OLPR, TPOMW, and beech sawdust (control) by H. erinaceus qualified OLPR in subsequent cultivation experiments, where it exhibited high mushroom yields and biological efficiency (31 %). Analyses of proximate composition and bioactive compound content revealed that mushrooms deriving from OLPR substrates showed significantly higher crude fat, total glucan, β-glucan, total phenolics, and ferric-reducing antioxidant potential values than the control. H. erinaceus demonstrated the potential to detoxify OMW and bioconvert OLPR into high-quality biomass, and hence, this fungus could be successfully exploited for the treatment of such by-products.

Two-phase olive mill waste (TPOMW, "alperujo") is a highly biotoxic sludge-like effluent of the olive-oil milling process with a huge seasonal production. One of the treatment approaches that has so far received little attention is the use of TPOMW as substrate for the cultivation of edible mushrooms. Fifteen fungal strains belonging to five species (Basidiomycota), that is, Agrocybe cylindracea, Pleurotus cystidiosus, P. eryngii, P. ostreatus, and P. pulmonarius, were evaluated for their efficacy to colonize media composed of TPOMW, which was used either raw or composted in mixtures with wheat straw in various ratios. Qualified strains exhibited high values of biological efficiency (e.g., 120-135% for Pleurotus spp. and 125% for A. cylindracea) and productivity in subsequent cultivation experiments on substrates supplemented with 20-40% composted TPOMW or 20% raw TPOMW. Only when supplementation exceeded 60% for raw TPOMW, a negative impact was noted on mushroom yields which could be attributed to the effluent's toxicity (otherwise alleviated in the respective composted TPOMW medium). Earliness and mushroom size as well as quality parameters such as total phenolic content and antioxidant activity did not demonstrate significant differences versus the control wheat-straw substrate. The substrates hemicellulose content was negatively correlated with mycelium growth rates and yields and positively with earliness; in addition, cellulose: lignin ratio presented a positive correlation with mycelium growth and mushroom weight for A. cylindracea and with earliness for all species examined. TPOMW-based media revealed a great potential for the substitution of traditional cultivation substrates by valorizing environmentally hazardous agricultural waste.