Edible Basidiomycete Research Articles

Cloning of Three Aflatoxin B1 Oxidases of the Dipeptidyl Peptidase III Family and Evaluation of Their Potential for Practical Applications as Decontamination Enzymes.

Aflatoxin B1 (AFB1) produced by some Aspergillus species belongs to the most dangerous contaminants of animal feeds. Development of safe and cost efficient decontamination methods saving feed quality and nutritional value are of paramount importance. The use of recombinant AFB1-detoxifying microbial enzymes represents a promising biotechnological approach meeting the aforementioned requirements. In this study, three AFB1-degrading oxidases (AFOs) from edible basidiomycetes Cantharellus cibarius, Lentinula edodes and Pleurotus eryngii as well as AFO from Armillaria tabescens were expressed in E. coli Rosetta (DE3) and purified by immobilized metal-chelate chromatography. The stabilizing effect of the addition of glycerol and β-mercaptoethanol during protein extraction is shown. The catalytic constants of the recombinant AFOs (rAFOs) and other characteristics, which might be important for their practical application (and optimal temperature and pH, thermolability, regulation of the activity by metal ions and chelating agents, storage stability) were investigated. Among the obtained enzymes, rAFO from P. eryngii (Pe-AFO), which was characterized by the highest specific activity, thermostability and pH stability (especially at acidic pH range), the lowest Km, and relative resistance to the inhibition by phytate, showed the best AFB1-degrading efficacy. However, Pe-AFO and all other rAFOs significantly decreased the target activity during heating above 45 °C, storage frozen or lyophilization.

Combining the Elicitor Up-Regulated Production of Unusual Linear Diterpene-Derived Variants for an In-Depth Assessment of the Application Value and Risk of the Medicinal and Edible Basidiomycete Schizophyllum commune.

To better assess the practical value and avoid potential risks of the traditionally medicinal and edible basidiomycete Schizophyllum commune, which may arise from undescribed metabolites, a combination of elicitors was introduced for the first time to discover products from cryptic and low-expressed gene clusters under laboratory cultivation. Treating S. commune NJFU21 with the combination of five elicitors led to the upregulated production of a class of unusual linear diterpene-derived variants, including eleven new ones (1-11), along with three known ones (12-14). The structures and stereochemistry were determined by 1D and 2D NMR, HRESIMS, ECD, OR and VCD calculations. Notably, the elongation terminus of all the diterpenes was decorated by an unusual butenedioic acid moiety. Compound 1 was a rare monocyclic diterpene, while 2-6 possessed a tetrahydrofuran moiety. The truncated metabolites 4, 5 and 13 belong to the trinorditerpenes. All the diterpenes displayed approximately 70% scavenging of hydroxyl radicals at 50 μM and null cytotoxic activity at 10 μM. In addition, compound 1 exhibited potent antifungal activity against the plant pathogenic fungi Colletotrichum camelliae, with MIC values of 8 μg/mL. Our findings indicated that this class of diterpenes could provide valuable protectants for cosmetic ingredients and the lead compounds for agricultural fungicide development.

Fermentation of soybeans with Pleurotus cornucopiae and Pleurotus ostreatus increases isoflavone aglycones, total polyphenol content and antioxidant activity.

Edible basidiomycetes are highly active in the oxidative decomposition and polymerisation of polyphenols, and soybeans contain large amounts of isoflavones, which are polyphenol glycosides. Isoflavone aglycones exhibit weak estrogenic activities. In this study, we investigated the isoflavone content, polyphenol production, antioxidant activity and ergothioneine (EGT) content of soybeans fermented by Pleurotus cornucopiae and Pleurotus ostreatus. Isoflavone glycosides, which were abundant in unfermented soybeans, decreased, and aglycones increased on day 10 of culture in both edible basidiomycete-fermented soybeans. The total maximum polyphenol content in soybeans fermented by both mushrooms were approximately 4 times higher on day 30 to 40 of culture, than that of unfermented soybeans. P. cornucopiae-fermented soybeans showed maximum antioxidant activity on day 20 of culture, and this was approximately 6.1 times higher than that of unfermented soybeans. EGT was not detected in unfermented soybeans, whereas both fermented soybeans showed a maximum EGT content on day 20 of culture, which was especially high in P. cornucopiae-fermented soybeans. The antioxidant activity and EGT of P. cornucopiae-fermented soybeans were higher than those of P. ostreatus, suggesting that EGT was responsible for the increase in the antioxidant activity of P. cornucopiae-fermented soybeans.

Macrofungi as Medicinal Resources in Uzbekistan: Biodiversity, Ethnomycology, and Ethnomedicinal Practices.

Interest in edible and medicinal macrofungi is millennial in terms of their uses in health and food products in Central Asia, while interest in inedible and medicinal macrofungi has grown in popularity in recent years. Edible and inedible medicinal basidiomycetes were collected during field surveys from different regions of Uzbekistan. The morphological characters and similarity assessment of rDNA-Internal Transcribed Spacer sequence data were used to measure diversity and habitat associations. A number of 17 species of medicinal macrofungi of ethnomycological and medicinal interest was found associated with 23 species of trees and shrubs belonging to 11 families and 14 genera. Polyporaceae and Hymenochaetaceae were represented by the highest number of species followed by Ganodermataceae, Fomitopsidaceae, Auriculariaceae, Cerrenaceae, Grifolaceae, Phanerochaetaceae, Laetiporaceae, Schizophyllaceae, and Stereaceae. The highest number of medicinal basidiomycete species was reported in the following host genera: Acer, Betula, Celtis, Crataegus, Juglans, Juniperus, Lonicera, Malus, Morus, Platanus, Populus, Prunus, Quercus, and Salix. An updated list of edible and inedible medicinal mushrooms identified in Uzbekistan, their morphological characteristics, and phylogenetic placement are given for the first time. Information is provided on their uses in traditional and modern medicine. Their bioactive compounds and extracts can be applied as medicines, as well as food and cosmetic ingredients.

Suitability of maize crop residue fermented by Pleurotus ostreatus as feed for edible crickets: growth performance, micronutrient content, and iron bioavailability.

Small-scale farming of edible insects could help combat public health challenges such as protein energy malnutrition and anemia, but reliable low-cost feeds for insects are needed. In resource-limited contexts, where grains such as maize are prohibitively costly for use as insect feed, the feasibility of insect farming may depend on finding alternatives. Here, we explore the potential to modify plentiful maize crop residue with edible mushroom mycelium to generate a low-cost feed adjunct for the farmed two-spotted cricket, Gryllus bimaculatus. Mushroom farming, like insect agriculture, is versatile; it can yield nutritious food while increasing system circularity by utilizing lignocellulosic residues from row crops as inputs. Pleurotus ostreatus, is an edible basidiomycete capable of being cultivated on corn stover (Zea mays). Mushroom harvest results in abundant "spent" substrate, which we investigated as a candidate feed ingredient. We created six cricket feeds containing fermented Pleurotus substrate plus an unfermented control, measuring cricket mass, mortality, and maturation weekly to evaluate cricket growth performance impacts of both fungal fermentation duration and mushroom formation. Pasteurized corn stover was inoculated with P. ostreatus mycelium and fermented for 0, 2, 3, 4, or 8 weeks. Some 4 and 8-week substrates were induced to produce mushrooms through manipulations of temperature, humidity, and light conditions. Dried fermented stover (40%) was added to a 1:1 corn/soy grain mix and fed to crickets ad libitum for 44 days. The unfermented control group showed higher survivorship compared to several fermented diets. Control group mass yield was higher for 2 out of 6 fermented diets. Little variation in cricket iron content was observed via ICP-spectrometry across feeds, averaging 2.46 mg/100 g. To determine bioavailability, we conducted in vitro Caco-2 human colon epithelial cell absorption assays, showing that iron in crickets fed fruiting-induced substrates was more bioavailable than in unfruited groups. Despite more bioavailable iron in crickets reared on post-fruiting substrates, we conclude that Pleurotus-fermented stover is an unsuitable feed ingredient for G. bimaculatus due to high mortality, variability in growth responses within treatments, and low mass yield.

Enhancing submerged fermentation of Antrodia camphorata by low-frequency alternating magnetic field

This work aimed to investigate the impact of low-frequency (30–300 kHz) alternating magnetic field (LF-AMF) on enhancing submerged fermentation of Antrodia camphorata (A. camphorata), a basidiomycete fungus. This study assessed mycelial biomass, active metabolites, microstructure, cytomembrane fluidity, and molecular mechanism. Under optimal magnetic treatment conditions, the mycelial biomass and the yields of polysaccharides and triterpenoids increased by 15.88, 24.26, and 26.85% at laboratory level and 8.99, 20.81, and 29.91% at scale-up level, respectively, compared with the control. The microstructures displayed that the magnetically treated mycelium showed a rough, loose, and wrinkled surface morphology, a slightly thinner cell wall, and enlarged vesicle and mitochondrial volume compared with the control. The cytomembrane fluidity increased over the magnetic exposure time. Transcriptomic analysis revealed that LF-AMF treatment enhanced the mycelium growth of A. camphorata by significantly up-regulating gene expression related to amino acid metabolism and synthesis and cell growth. Additionally, unigenes involved in RNA transport and endocytosis were up-regulated in response to magnetic stimulation to promote the accumulation of the active metabolites. Industrial relevanceA. camphorata is a precious edible medicinal basidiomycete with various pharmaceutical activities and high commercial value. However, the wild fruiting bodies of A. camphorata are scarce and expensive due to the host specificity and slow growth rate in nature. Our findings indicated that LF-AMF-assisted-submerged fermentation could be considered an effective way to produce A. camphorata mycelia at laboratory and scale-up levels, achieving efficient, high-quality, and large-scale production of precious edible fungus.

Biotransformation of Wastes of Essential Oil Industry by Strains Agaricus bisporus (J.E. Lange) Imbach, Lentinula edodes (Berk.) Pegler, and Pleurotus ostreatus (Jacq.) P. Kumm

The aim of the present work was to explore insights into the possibility of cultivating the mycelium of the edible basidiomycetes, i.e., Agaricus bisporus (J.E. Lange) Imbach, Lentinula edodes (Berk.) Pegler, and Pleurotus ostreatus (Jacq.) P. Kumm. on wastes produced from lavender, sage, mint, and rose. To achieve this goal, we assessed the growth and development of strains on various substrates, a component analysis of the biomass of strains, initial essential oil raw materials after processing, and raw materials after exposure to the mycelium of basidial fungi strains. The wastes of essential oil production can be transformed with the help of edible basidiomycetes (A. bisporus, L. edodes, P. ostreatus) into a valuable fodder product enriched with proteins and vitamins and with good organoleptic properties. The best of the tested substrates was the green mass of mint after successive distillation and extraction. The conversion of solid waste from lavender, rose, sage, and mint processing depends on the types of strains. The high accumulation of octen-3-ol (up to 1.38 g/kg of the substrate) by P. ostreatus was confirmed by its organoleptic evaluation. The results suggested the cultivation of edible mushroom mycelium on the solid waste of mint, lavender, and sage processing could produce high-grade (enriched in proteins and vitamins) biomass for the purpose of fodder. These by-products could serve as a basis for the creation of cultivation technology for champignon, shiitake, and oyster mushrooms as food products using secondary resources of essential oil production.

Chemical Characterization and Bioactive Properties of the Edible and Medicinal Honey Mushroom Armillaria mellea (Agaricomycetes) from Serbia

Honey mushroom, Armillaria mellea, is an edible and medicinal lignicolous basidiomycete. In this study, we investigated the chemical composition and bioactive properties of its methanolic and acetonic extracts. The chemical characterization of extracts was done with the HPLC-DAD-MS/MS method. The results showed that potassium was the most abundant mineral; chlorogenic acid was the most abundant polyphenol; malic acid was the most abundant organic acid; and among carbohydrates, the most abundant were sorbitol, glucose, fructose, and saccharose. Antioxidative activity was assessed by DPPH (IC50 of the methanolic extract was 608.32 μg/mL and of the acetonic extract 595.71 μg/mL) and reducing power assays (the results ranged between 0.034 and 0.102 μg/mL). Total phenolic content was determined as gallic acid equivalent (methanolic extract: 4.74 mg GAE/g; acetonic extract: 5.68 mg GAE/g). The microdilution assay was used to evaluate the antimicrobial activity of the extracts, and the results ranged from 1.25 to 20 mg/mL. The antidiabetic effect of the extracts was tested by the α-amylase (the results ranged from 34.90% to 41.98%) and α-glucosidase assays (the results were in the range of 0.55-2.79%). The neuroprotective activity was explored by the acetylcholinesterase inhibition assay (the results were in the range of 1.94-7.76%). The microtetrazolium assay was used to investigate the cytotoxic activity of the extracts (the IC50 values ranged from 212.06 to > 400 μg/mL). Although some results suggest that some activities of the extracts are relatively moderate, the honey mushroom can still be considered an excellent source of food and bioactive compounds with medicinal value.

Immunomodulatory activity of extracts from five edible basidiomycetes mushrooms in Wistar albino rats

Mushrooms are nutritious foods that are widely cultivated all over the world. They are rich in a range of compounds linked to improving functions of the immune system including carotenoids, alkaloids, lectins, enzymes, folates, fats, organic acids, minerals, polysaccharides, phenolics, proteins, tocopherols, terpenoids, and volatile compounds. In this study we investigated, the immunomodulatory activity in rats of the aqueous extracts of five of the most common edible mushrooms belonging to Family Basidiomycota-white-rot fungi including, Lentinula edodes, Agaricus bisporus, Pleurotus ostreatus, Pleurotus columbinus, and Pleurotus sajor-caju. Male Wistar albino rats were assigned to thirteen groups and Immunosuppression was induced by oral administration of dexamethasone (0.1 mg/kg), followed by oral administration of the mushroom extracts at low (200 mg/kg) and high (400 mg/kg) doses. A positive control group received the immune stimulant Echinacea extract Immulant® at (30 mg/kg), while the negative control group received only saline. From each animal, in each group, blood samples were collected after 15 days for complete blood counts and for measurement of immunologic parameters, including lysozyme activity, nitric oxide (NO) production and serum cytokines including tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ) and interleukin 1 beta (IL-1β) levels. Results have shown that white blood cells (WBCs) and lymphocytic counts were significantly boosted by high doses of each of the five mushroom extracts (207–289% increase for WBC and 153–175% for lymphocytes) with a significant increase in lysozyme activity (110–136% increase), NO concentration (159–232% increase) and cytokines as compared to the negative control group. Histopathological examination of the rats' spleen and thymus tissues has shown marked lymphocytic proliferation that was more obvious at the higher doses. In conclusion, our results showed that the five edible mushroom extracts revealed significant immunostimulatory effects preclinically particularly, at the higher doses (400 mg/kg) which can be considered the effective dose.

Virome of Three Termite Species from Southern Vietnam.

Modern metagenomic approaches enable the effective discovery of novel viruses in previously unexplored organisms. Termites are significant ecosystem converters and influencers. As with the majority of tropical forest insects, termites are studied insufficiently, and termite virome remains especially understudied. Here, we studied the virome of lichenophagous and mycophagous termites (Hospitalitermes bicolor, Macrotermes carbonarius and Odontotermes wallonensis) collected in the Cat Tien National Park (Vietnam). We assembled four full genomes of novel viruses related to Solemoviridae, Lispiviridae, Polycipiviridae and Kolmioviridae. We also found several contigs with relation to Chuviridae and Deltaflexiviridae that did not correspond to complete virus genomes. All the novel viruses clustered phylogenetically with previously identified viruses of the termites. Deltaflexi-like contigs were identified in the fungi-cultivating M. carbonarius and showed homology with viruses recently discovered in the edible basidiomycete mushrooms.

Improved Foods Using Enzymes from Basidiomycetes

Within the kingdom of fungi, the division Basidiomycota represents more than 30,000 species, some with huge genomes indicating great metabolic potential. The fruiting bodies of many basidiomycetes are appreciated as food (“mushrooms”). Solid-state and submerged cultivation processes have been established for many species. Specifically, xylophilic fungi secrete numerous enzymes but also form smaller metabolites along unique pathways; both groups of compounds may be of interest to the food processing industry. To stimulate further research and not aim at comprehensiveness in the broad field, this review describes some recent progress in fermentation processes and the knowledge of fungal genetics. Processes with potential for food applications based on lipases, esterases, glycosidases, peptidases and oxidoreductases are presented. The formation and degradation of colourants, the degradation of harmful food components, the formation of food ingredients and particularly of volatile and non-volatile flavours serve as examples. In summary, edible basidiomycetes are foods—and catalysts—for food applications and rich donors of genes to construct heterologous cell factories for fermentation processes. Options arise to support the worldwide trend toward greener, more eco-friendly and sustainable processes.

Isolation, Structural Properties, and Bioactivities of Polysaccharides from Mushrooms Termitomyces: A Review

Termitomyces are well-known wild edible and medicinal basidiomycete mushrooms. The frequent consumption of Termitomyces stimulated studies on their health-promoting properties. Numerous health benefits of Termitomyces are associated with the main categories of components in Termitomyces, polysaccharides. Although the homopolysaccharides β-glucans are believed to be the major bioactive polysaccharides of Termitomyces, other heteropolysaccharides also possess biological activities. In this review, the extraction methods, chemical structures, and biological activities of polysaccharides from Termitomyces were thoroughly reviewed. The polysaccharides from different species of Termitomyces differ in molecular weight, monosaccharide composition, and linkages of constituent sugars. The health-promoting effects, including antioxidation, ulcer-healing and analgesic properties, immunomodulation, hypolipidemic and hepatoprotective effects, and antidiabetic properties of Termitomyces polysaccharides were summarized and discussed. Further studies were needed for a better understanding of the relationship between the fine chemical structure and health-promoting properties. This review provides a theoretical overview for future studies and utilization of Termitomyces polysaccharides.

Armillaria luteo-virens Sacc Ameliorates Dextran Sulfate Sodium Induced Colitis through Modulation of Gut Microbiota and Microbiota-Related Bile Acids.

Armillaria luteo-virens Sacc (ALS) is a rare wild Chinese medicinal and edible basidiomycete. However, its protective effect on intestinal functions and the underlying mechanism is still unknown. This work explored the improvement of dextran sulfate sodium (DSS)-induced colitis by ALS. ALS supplementation markedly improved colitis symptoms, gut barrier integrity, and goblet loss in DSS-treated mice. In addition, ALS inhibited colonic inflammation through the inhibition/activation of the mitogen-activated protein kinases/NF-κB signaling pathway. The 16S rRNA gene-based microbiota analysis revealed that ALS altered the gut microbiota composition, decreasing the richness of Enterobacteriaceae and increasing the abundance of Lactobacillaceae. The bile-acid-targeted metabolomic analysis showed that ALS recovered the microbial bile acid metabolism in the gut, enabling the activation of the farnesoid X receptor signaling by these acids, thus maintaining the intestinal homeostasis. Importantly, broad-spectrum antibiotic treatment reduced the efficacy of ALS-induced protection from colitis. Overall, our findings suggest that ALS may represent a novel approach in the nutritional intervention to prevent colitis.

Investigation on the uptake of ciprofloxacin, chloramphenicol and praziquantel by button mushrooms

Button mushrooms are widely produced edible basidiomycetes. Commercially, they are cultivated on substrates containing fermented horse manure and chicken feces. Since pharmacologically active substances (PAS) might be introduced into the food chain via animal treatment, their residues may be present in manure used for mushroom growth. Previous studies in plants have demonstrated an uptake of PAS from the agricultural environment. The present study was performed to investigate the presence of PAS in button mushrooms. For analysis, a multi-analyte method for the detection of 21 selected PAS using liquid chromatography tandem-mass spectrometry was developed, successfully validated and applied to commercially available button mushrooms. Traces of chloramphenicol were detected in two of 20 samples. Additionally, in a mushroom cultivation experiment an uptake of ciprofloxacin, chloramphenicol and praziquantel was conducted. Throughout the whole experiment, praziquantel was present in quantifiable amounts in mushrooms and in high quantities in soil.

Ageritin from Pioppino Mushroom: The Prototype of Ribotoxin-Like Proteins, a Novel Family of Specific Ribonucleases in Edible Mushrooms.

Ageritin is a specific ribonuclease, extracted from the edible mushroom Cyclocybe aegerita (synonym Agrocybe aegerita), which cleaves a single phosphodiester bond located within the universally conserved alpha-sarcin loop (SRL) of 23–28S rRNAs. This cleavage leads to the inhibition of protein biosynthesis, followed by cellular death through apoptosis. The structural and enzymatic properties show that Ageritin is the prototype of a novel specific ribonucleases family named ‘ribotoxin-like proteins’, recently found in fruiting bodies of other edible basidiomycetes mushrooms (e.g., Ostreatin from Pleurotus ostreatus, Edulitins from Boletus edulis, and Gambositin from Calocybe gambosa). Although the putative role of this toxin, present in high amount in fruiting body (>2.5 mg per 100 g) of C. aegerita, is unknown, its antifungal and insecticidal actions strongly support a role in defense mechanisms. Thus, in this review, we focus on structural, biological, antipathogenic, and enzymatic characteristics of this ribotoxin-like protein. We also highlight its biological relevance and potential biotechnological applications in agriculture as a bio-pesticide and in biomedicine as a therapeutic and diagnostic agent.

Antifungal Basidiomycete Extracts with Phytosanitary Potential

Excessive use of chemical fungicides continues to drive research towards biological alternatives, as natural products are enjoying increasing interest in many areas and have the potential to control biological agents that cause various diseases in agricultural crops. On the other hand, the biodiversity of Basidiomycetes fungi is well recognized as an untapped source of potential bioactive of natural origin, with original chemical and biological characteristics, having prospective activities of medical and biological interest. These macro-fungi are among the main biological agents used to fight against phy-topathogenic fungi. The present study was carried out to evaluate the anti-fungal activity of ethyle acetate extracts of 16 edible and no edible basidiomycetes. These mushrooms are: Lactarius zonarioides, Amanita proxima, A.virosa, Agaricus bisporus, Suillus mediterraneensis, Coprinus atramentari-us, Pleurotus pulmonarius, P. eryngi, P. dryinus, P. ostreatus, Lepiota sp., Cortinarius orellanus, Boletus sp., Xerocomus sp., Armillaria mellea, and Trametes quercina. Their phytosanitary potential was tested against three phytopathogenic fungi: Aspergillus niger; Fusarium oxysporum f.sp. albedinis and Verticillium dahliae Kleb. The chemical extraction by the apparatus Soxhlet was used to obtain ethyl acetate extracts from different basidiocarps, and the disc diffusion method was done in order to achieve antifungal activity. The results showed that; among the studied extracts; those of A. proxima, A. virosa, Xerocomus sp. and Trametes quercina have a potential antifungal activity compared with standard Fluconazol. These results clearly indicated that basidiomycete extracts are a reservoir of bioactive components of antimicrobial fungal metabolites, which could be used for the devel-opment of new agents against phytopathogenic fungi.

Complete mitochondrial genome of the edible Basidiomycete mushroom Thelephora aurantiotincta (Aphyllophorales: Thelephoraceae) from China

The complete mitochondrial genome of Thelephora aurantiotincta, an edible Basidiomycete mushroom species with ecological and economic value is reported in this study. The whole genome is a circular molecule 50,672 bp in length and encodes 42 genes as follows: 15 protein-coding genes, two rRNA genes and 25 tRNA genes. The A, T, C, G contents in the genome are 35.60%, 35.31%, 13.89%, and 15.20%, respectively. Phylogenetic analysis revealed a close relationship between T. aurantiotincta and T. ganbajun. This is the first complete mitochondrial genome for T. aurantiotincta that will be useful for providing basic genetic information for this important species.

In silico characterization of laccase gene isoforms of edible and medicinal basidiomycetes

Laccases are part of the family of ligninolytic enzymes and have played essential roles in several biological filamentous fungi processes, including fruiting body formation and lignin degradation. This study aimed to identify and characterize laccase genes in silico of several basidiomycete strains. The applied guaiacol oxidation test allowed the selection of seven out of 11 strains with ligninase activity, which were used for DNA extraction and amplification of the copper-binding region. A single amplicon of approximately 450 bp, was produced by all selected strains and they were further sequenced. Sequence analysis has suggested the presence of a new subdivision of the laccase genes. Clustering analysis confirmed the existence of two groups: cluster A with six strains and singleton B with U8-11 strain. The structural predictions of the U8-11 protein were dissimilar compared to other proteins described in our study due to the absence of the ALAVIN motif and, therefore, the U8-11 amino acid sequence was separated in a different cluster.

Biosynthesis of pleasant aroma by enokitake (Flammulina velutipes) with a potential use in a novel tea drink

Western consumers prefer tea products with little or no green flavor. Accordingly, edible basidiomycetes have been addressed as an innovative tool to naturally aromatize tea infusion to mask or reduce green flavor. After submerged fermentation of green tea infusion with basidiomycetes, multiple pleasant odor impressions were perceived which significantly differed from the characteristic green and floral odor of the substrate. Among twenty-nine screened fungi, enokitake (Flammulina velutipes) was regarded as an ideal species to potentially drive a sensorial tea drink because of its appealing nutty and chocolate-like flavor and a rapid fermentation process (16 h). To better understand flavor formation during fermentation as perceived by sensory evaluation, the flavor profile was decoded by direct immersion – stir bar sorptive extraction – gas chromatography – mass spectrometry – olfactometry. During the fermentation, a series of key odorants of the non-fermented tea infusion imparting green and floral were decreased, while compounds responsible for the nutty and chocolate-like aroma increased. Enokitake biosynthesized the sensory-relevant compound 2-ethyl-3,5-dimethylpyrazine, which has not been reported in basidiomycetes yet. We assume that vitamin B1 and sodium acetate are potential precursors in enokitake. In parallel, the accumulation of various alkylpyrazines (2,5-dimethylpyrazine, 2,3,5-trimethylpyrazine, and 2-ethyl-3,6-dimethylpyrazine) has been observed as well.

Valorization of low-cost, carbon-rich substrates by edible ascomycetes and basidiomycetes grown on liquid cultures.

Three ascomycetes (Morchella vulgaris AMRL 36, M. elata AMRL 63, Tuber aestivum AMRL 364) and four basidiomycetes strains (Lentinula edodes AMRL 124 and 126, Agaricus bisporus AMRL 208 and 209) were screened for their ability to grow on liquid static flask cultures of glucose, glycerol, molasses and waste flour-rich hydrolysates with C/N ratio of 20 and produce biomass, exopolysaccharides and lipids. The profile of lipid fatty acids was also assessed. Selected strains were furthermore cultivated in C/N=50. Results showed that substrate consumption, biomass formation and secondary metabolites production were strain, substrate and C/N ratio dependent. The maximum biomass (X), lipid (L) and exopolysaccharides (EPS) values noted were Xmax=25.2g/L (C/N=20; molasses) and Lmax=6.51g/L (C/N=50; rice cereal hydrolysates) by T. aestivum strain AMRL 364 and EPSmax=2.41g/L by M. elata strain AMRL 63 (C/N=50; molasses), respectively. When C/N ratio of 50 was applied, biomass, lipid production and substrate consumption seem to be negatively affected in most of the trials. The adaptation and capability of the mushroom strains to be cultivated on substrates based on agro-industrial waste streams and infant food of expired shelf date offers the opportunity to set a circular oriented bioprocess.