[Research progress on structures, activities, and biosynthesis of blazeispirol compounds from Agaricus blazei]

Agaricus blazei is a rare medicinal and edible fungus with a crispy taste and delicious flavor. Both fruiting body and mycelium are rich in polysaccharides, sterols, terpenoids, peptides, lipids, polyphenols, and other active ingredients, which have strong pharmacological activities such as anti-tumor, lipid-lowering, glucose-lowering, immunomodulation, optimization of intestinal flora, and anti-oxidation. Therefore, it is a kind of fungal resource with a great prospect of edible and medicinal development. Among the reported chemical components of A. blazei, blazeispirol is a series of sterol compounds unique to A. blazei, which has a spiral structure and is different from classical steroids. It is an important active ingredient found in the mycelium of A. blazei and has significant hepatoprotective activity. It can be used as a phylogenetic and chemotaxonomic marker of A. blazei strains and is considered an excellent lead compound for drug development. According to the skeleton structure characteristics, the 17 discovered blazeispirol compounds can be divided into two types: blazeispirane and problazeispirane. In order to further explore the resource of blazeispirol compounds of A. blazei, the discovery, isolation, structure, biological activity, and biosynthetic pathways of blazeispirol compounds of A. blazei were systematically reviewed. Besides, the metabolic regulation strategies related to the fermentation synthesis of blazeispirol A by A. blazei were discussed. This review could provide a reference for the efficient synthesis and development of blazeispirol compounds, the research and development of related drugs and functional foods, and the quality improvement of A. blazei and other medicinal and edible fungi resources and derivatives.

Transcriptome and Hormonal Analysis of Agaricus bisporus Basidiome Response to Hypomyces perniciosus Infection

Agaricus bisporus (Lange) Imbach is the most widely cultivated mushroom in the world. A. bisporus wet bubble disease is one of the most severe diseases of white button mushrooms and is caused by the fungal pathogen Hypomyces perniciosus. The pathogen causes a drastic reduction in mushroom yield because of malformation and deterioration of the basidiomes. However, the mechanism of the button mushroom's malformation development after infection with H. perniciosus remains obscure. Therefore, to reveal the mechanism of A. bisporus malformation caused by H. perniciosus, the interaction between the pathogen and host was investigated in this study using histopathological, physiological, and transcriptomic analyses. Results showed that irrespective of the growth stages of A. bisporus basidiomes infected with H. perniciosus, the host's malformed basidiomes and enlarged mycelia and basidia indicated that the earlier the infection with H. perniciosus, the more the malformation of the basidiomes. Analyzing physiological and transcriptomic results in tandem, we concluded that H. perniciosus causes malformation development of A. bisporus mainly by affecting the metabolism level of phytohormones (N6-isopentenyladenosine, cis-zeatin, and N6-[delta 2-isopentenyl]-adenine) of the host's fruiting bodies rather than using toxins. Our findings revealed the mechanism of the button mushroom's malformation development after infection with H. perniciosus, providing a reference for developing realistic approaches to control mushroom diseases. Our results further clarified the interaction between A. bisporus and H. perniciosus and identified the candidate genes for A. bisporus wet bubble disease resistance breeding. Additionally, our work provides a valuable theoretical basis and technical support for studying the interaction between other pathogenic fungi and their fungal hosts.

Gastroprotective effect of hydroalcoholic extract from Agaricus blazei Murill against ethanol-induced gastric ulcer in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The use of mushrooms in medicine is quite old and the first report about the use of genus Agaricus in treatment of ulcers occurred in Byzantine period. This mushroom is widely consumed as food, tea, food supplements, as well as nutraceutical and cosmeceutical applications, being cultivated and appreciated in several countries such as Brazil, Korea, Japan and China.

AIM OF THE STUDY

This study aimed to characterize the chemical profile and the potential gastroprotective effect of hydroalcoholic extract from Agaricus blazei Murill (HEAb).

MATERIALS AND METHODS

The extract was chemically characterized by elemental analysis, UPLC-QTOF-MS^E, Nuclear Magnetic Resonance (NMR) and high-performance liquid chromatography (HPLC) techniques to elucidate the metabolites present in the extract. The quantification of phenolic compounds and the in vitro antioxidant activities were performed and the gastroprotective effect of this extract was evaluated against ethanol-induced gastric ulcer model. HEAb was administered by gavage at 5, 25 and 50 mg kg^-1 and N-acetylcysteine at 300 mg kg^-1 (positive control). Furthermore, the pathways of nitric oxide (NO), Cyclic Guanylate Monophosphate (cGMP), prostaglandins (PGs) and the involvement of ATP-sensitive K⁺ Channels were modulated.

RESULTS

Mannitol, malic acid, pyroglutamic acid, L-agaritine and L-valine were putatively identified by UPLC-QTOF-MS^E in HEAb. In addition, it was possible to identify mannitol by the intense signals in the NMR spectra, being still quantified as the main compound in the extract by HPLC. The contents of total phenols and flavonoids corroborated with the good antioxidant activity of HEAb. This study observed that HEAb at 25 and 50 mg kg^-1 had gastroprotection effect demonstrated by the reduction of histopathological parameters and the reduction of mastocytosis in the stomach of mice.

CONCLUSIONS

In this study was possible to conclude that HEAb has gastroprotective effect related to the involvement of NO and PG pathways in the ethanol-induced gastric ulcer model in mice.

Valorization of dietary edible mushrooms waste: chemical and physical properties, nutrient digestibility, microbial protein synthesis and nitrogen balance in sheep

BACKGROUND

The optimal use of feed resources must be considered by most livestock farmers. The use of low-cost agricultural by-products and the processing of these materials is one possible solution in this respect. One such compound is edible button mushroom waste (EM), a large amount of which is produced annually in the mushroom production cycle worldwide.

RESULTS

Bulk density 100 of EM was smaller than the other groups. These changes also applied to alfalfa for bulk density, which was higher than the replaced waste. The dry matter solubility of EM was higher than that of alfalfa hay, whereas the ash solubility rate for EM was greater compared to alfalfa. Replacing up to 210 g kg^-1 alfalfa with EM did not affect the production of purine derivatives, microbial protein, nitrogen excreted in urine and feces, and retained nitrogen, although the organic matter digestibility (OMD) increased, whereas the crude protein digestibility and neutral detergent fiber (NDF) decreased (P < 0.05). Fermentation potential, gas production rate, metabolizable energy and short-chain fatty acids were increased. On replacing up to 210 g kg^-1 alfalfa with EM, the diet OMD increased, whereas the crude protein and NDF digestibility decreased (P < 0.05).

CONCLUSION

EM usage in the experimental diets did not affect the production of purine derivatives, microbial protein, nitrogen excreted in urine and feces, and retained nitrogen. The physical properties, chemical composition and nutritional value of EM, as well as its low cost, show that it can be used as an alternative part of the diet forage in the ruminant's diet. © 2021 Society of Chemical Industry.

A New Biotechnology Method of Bioelements' Accumulation Monitoring in In Vitro Culture of Agaricus bisporus

Agaricus bisporus (J.E. Lange) Imbach is one the most popular species of edible mushrooms in the world because of its taste and nutritional properties. In the research, repeatability of accumulation of bioelements and biomass yield in experimentally chosen in vitro culture medium, was confirmed. The in vitro cultures were conducted on the modified Oddoux medium enriched with bioelements (Mg, Zn, Cu, Fe). The aim of the study was to create an effective method of sampling, which enabled non-invasive monitoring of metals concentrations changes in the medium, during increase of biomass in in vitro cultures. The first, indirect method of sampling was applied. The non-invasive probe (a dipper) for in vitro culture was used; hence, the highest biomass increase and metals accumulation were gained. The method also guaranteed culture sterility. The second method, a direct one, interfered the in vitro culture conditions and growth of mycelium, and as a consequence the lower biomass increase and metals' accumulation were observed. Few cases of contaminations of mycelium in in vitro cultures were observed. The proposed method of non-invasive sampling of the medium can be used to monitor changes in the concentrations of metals in the medium and their accumulation in the mycelium in natural environment. Changes in concentrations of the selected metals over time, determined by the method of atomic absorption spectrometry, made it possible to correlate the obtained results with the specific stages of A. bisporus mycelium development and to attempt to explain the mechanism of sampling metals from the liquid substrate.

Mating-Type Locus Organization and Mating-Type Chromosome Differentiation in the Bipolar Edible Button Mushroom Agaricus bisporus

In heterothallic basidiomycete fungi, sexual compatibility is restricted by mating types, typically controlled by two loci: PR, encoding pheromone precursors and pheromone receptors, and HD, encoding two types of homeodomain transcription factors. We analysed the single mating-type locus of the commercial button mushroom variety, Agaricus bisporus var. bisporus, and of the related variety burnettii. We identified the location of the mating-type locus using genetic map and genome information, corresponding to the HD locus, the PR locus having lost its mating-type role. We found the mip1 and β-fg genes flanking the HD genes as in several Agaricomycetes, two copies of the β-fg gene, an additional HD2 copy in the reference genome of A. bisporus var. bisporus and an additional HD1 copy in the reference genome of A. bisporus var. burnettii. We detected a 140 kb-long inversion between mating types in an A. bisporus var. burnettii heterokaryon, trapping the HD genes, the mip1 gene and fragments of additional genes. The two varieties had islands of transposable elements at the mating-type locus, spanning 35 kb in the A. bisporus var. burnettii reference genome. Linkage analyses showed a region with low recombination in the mating-type locus region in the A. bisporus var. burnettii variety. We found high differentiation between β-fg alleles in both varieties, indicating an ancient event of recombination suppression, followed more recently by a suppression of recombination at the mip1 gene through the inversion in A. bisporus var. burnettii and a suppression of recombination across whole chromosomes in A. bisporus var. bisporus, constituting stepwise recombination suppression as in many other mating-type chromosomes and sex chromosomes.

Effect of conservation methods on the bioaccessibility of bioelements from in vitro-digested edible mushrooms

BACKGROUND

The release of bioelements from edible mushrooms (Agaricus bisporus, Cantharellus cibarius, and Imleria badia) was examined using in vitro simulated gastrointestinal digestion to assess their health-promoting potential. The following samples were tested: fresh, frozen, dried in a food dryer, dried in the sun, and lyophilized. The samples were incubated in gastric juice (pepsin, NaCl, HCl) and in intestinal juice (NaHCO₃ , pancreatin, bile salts) with the aim of verifying the bioaccessibility of the bioelements and the digestibility of mushrooms. Four bioelements that are essential for the human body were studied: Mg, Zn, Cu, and Fe.

RESULTS

It was found that Mg was extracted in the highest amounts from the sun-dried A. bisporus (1.620 g kg^-1 d.w.). In the case of microelements, the lyophilized fruiting bodies of I. badia released Zn in the highest quantities (0.180 g kg^-1 d.w.). Lyophilization and sun-drying methods were more advantageous than other methods. Fresh material was a more valuable source of bioelements than frozen material.

CONCLUSION

Our results showed that edible mushrooms have a high content of bioelements that are easily bioaccessible, which indicates their health-promoting properties. © 2020 Society of Chemical Industry.

Generation of Iron-Independent Siderophore-Producing Agaricus bisporus through the Constitutive Expression of hapX

Agaricus bisporus secretes siderophore to uptake environmental iron. Siderophore secretion in A. bisporus was enabled only in the iron-free minimal medium due to iron repression of hapX, a transcriptional activator of siderophore biosynthetic genes. Aiming to produce siderophore using conventional iron-containing complex media, we constructed a recombinant strain of A. bisporus that escapes hapX gene repression. For this, the A. bisporushapX gene was inserted next to the glyceraldehyde 3-phosphate dehydrogenase promoter (pGPD) in a binary vector, pBGgHg, for the constitutive expression of hapX. Transformants of A. bisporus were generated using the binary vector through Agrobacterium tumefaciens-mediated transformation. PCR and Northern blot analyses of the chromosomal DNA of the transformants confirmed the successful integration of pGPD-hapX at different locations with different copy numbers. The stable integration of pGPD-hapX was supported by PCR analysis of chromosomal DNA obtained from the 20 passages of the transformant. The transformants constitutively over-expressed hapX by 3- to 5-fold and sidD, a key gene in the siderophore biosynthetic pathway, by 1.5- to 4-fold in mRNA levels compared to the wild-type strain (without Fe³⁺), regardless of the presence of iron. Lastly, HPLC analysis of the culture supernatants grown in minimal medium with or without Fe³⁺ ions presented a peak corresponding to iron-chelating siderophore at a retention time of 5.12 min. The siderophore concentrations of the transformant T2 in the culture supernatant were 9.3-fold (−Fe³⁺) and 8-fold (+Fe³⁺) higher than that of the wild-type A. bisporus grown without Fe³⁺ ions, while no siderophore was detected in the wild-type supernatant grown with Fe³⁺. The results described here demonstrate the iron-independent production of siderophore by a recombinant strain of A. bisporus, suggesting a new application for mushrooms through molecular biological manipulation.

Influence of cellulose nanocrystals gellan gum-based coating on color and respiration rate of Agaricus bisporus mushrooms

The edible coating has been used for covering fruits and vegetables, bringing surface protection, and extending product shelf-life. Due to the outstanding properties, nanomaterials have become a part of the packaging/coating new generation, demonstrating improvements in the barrier capacity of materials starting from construction products to the food industry. In the food industry, on the other hand, Agaricus bisporus mushrooms have a limited shelf-life from 1 to 3 days because of their high respiration rate and enzymatic browning. With the aim to reduce these two parameters and prevent rapid senescence, the objective of this study was to incorporate a natural source of nanomaterials (cellulose nanocrystals (CNCs) into a gellan gum-based coating and sprayed the surface of the mushrooms with the coating material. To evaluate the effect of CNCs, oxygen consumption, carbon dioxide production rate, and color change were recorded during the mushroom storage at 4 ± 1 °C. Results showed that all coatings were able to decrease total color change (ΔE) of mushrooms from 12 to 8 at day 10 when the coating was applied in all samples compared to control. In addition, significant differences were observed in the respiration rate when CNCs were added to the mushrooms. Oxygen consumption results exhibited a 44 mL O2 /kg · day production at day 5 with 20% CNCs compared to 269 mL O2 /kg · day observed in noncoated samples. This trend was similarly observed in the carbon dioxide production rate. PRACTICAL APPLICATION: With this research, it was remarkable to see the presence of CNCs in the coating solution reduced the respiration rate and increased the shelf-life of mushrooms. Similar applications can be industrially scaled-up to protect fruits and vegetables by CNCs-based coating or packaging materials. A variety of sustainable materials are available nowadays that serve as packaging matrix, and scientists are working on expanding the compatibility of these nanomaterials. In addition, it has been studied that CNCs enhance the degradation of polymers, an effort that many companies are making to reduce the environmental impact in their products.

Cycling in degradation of organic polymers and uptake of nutrients by a litter-degrading fungus

Wood and litter degrading fungi are the main decomposers of lignocellulose and thus play a key role in carbon cycling in nature. Here, we provide evidence for a novel lignocellulose degradation strategy employed by the litter degrading fungus Agaricus bisporus (known as the white button mushroom). Fusion of hyphae allows this fungus to synchronize the activity of its mycelium over large distances (50 cm). The synchronized activity has a 13-h interval that increases to 20 h before becoming irregular and it is associated with a 3.5-fold increase in respiration, while compost temperature increases up to 2°C. Transcriptomic analysis of this burst-like phenomenon supports a cyclic degradation of lignin, deconstruction of (hemi-) cellulose and microbial cell wall polymers, and uptake of degradation products during vegetative growth of A. bisporus. Cycling in expression of the ligninolytic system, of enzymes involved in saccharification, and of proteins involved in nutrient uptake is proposed to provide an efficient way for degradation of substrates such as litter.

Genomic Characterisation of Mushroom Pathogenic Pseudomonads and Their Interaction with Bacteriophages

Bacterial diseases of the edible white button mushroom Agaricus bisporus caused by Pseudomonas species cause a reduction in crop yield, resulting in considerable economic loss. We examined bacterial pathogens of mushrooms and bacteriophages that target them to understand the disease and opportunities for control. The Pseudomonastolaasii genome encoded a single type III protein secretion system (T3SS), but contained the largest number of non-ribosomal peptide synthase (NRPS) genes, multimodular enzymes that can play a role in pathogenicity, including a putative tolaasin-producing gene cluster, a toxin causing blotch disease symptom. However, Pseudomonasagarici encoded the lowest number of NRPS and three putative T3SS while non-pathogenic Pseudomonas sp. NS1 had intermediate numbers. Potential bacteriophage resistance mechanisms were identified in all three strains, but only P. agarici NCPPB 2472 was observed to have a single Type I-F CRISPR/Cas system predicted to be involved in phage resistance. Three novel bacteriophages, NV1, ϕNV3, and NV6, were isolated from environmental samples. Bacteriophage NV1 and ϕNV3 had a narrow host range for specific mushroom pathogens, whereas phage NV6 was able to infect both mushroom pathogens. ϕNV3 and NV6 genomes were almost identical and differentiated within their T7-like tail fiber protein, indicating this is likely the major host specificity determinant. Our findings provide the foundations for future comparative analyses to study mushroom disease and phage resistance.

Imidacloprid dissipation, metabolism and accumulation in Agaricus bisporus fruits, casing soil and compost and dietary risk assessment

An improved understanding of imidacloprid (IMI) metabolism and accumulation in casing soil or compost-mushroom systems will help to optimise the safe use of IMI for agricultural pest control in Agaricus bisporus cultivation. In this study, the dissipation, metabolites and accumulation of IMI in casing soil or compost-A. bisporus systems were investigated. The results show that the IMI dissipation half-lives at doses of 10 and 50 mg kg^-1 were 65 d and 59 d in casing soil and 6.6 d and 6.2 d in compost, respectively during the cultivation period. Three IMI metabolites were observed in casing soil during cultivation of mushrooms. Urea-imidacloprid (IMI-urea) was a major metabolite, accounting for more than 59%. In compost, the main metabolite in the first 5 days was IMI-urea, from 5 to 10 days olefin-imidacloprid (IMI-ole) and 6-chloronicotinic acid (6-CNA) were both the most prominent compounds, and after 10 days 6-CNA alone. At 50 mg kg^-1 dose, IMI and the metabolites (IMI-urea, IMI-ole) were detected in the fruiting body with IMI applied to casing soil and only the metabolite 6-CNA was detected in fruiting body with IMI applied to compost. The bio concentration factors (BCFs) of IMI-ole and IMI-urea were higher than of IMI and 6-CNA, and the BCFs had no obvious relationship with log K_ow. Furthermore, the potential dietary risk of IMI in A. bisporus was acceptable when application rates in casing soil or compost was up to 50 mg kg^-1. Our study supports a safe use of IMI as agricultural pest control in A. bisporus cultivation.

Critical Factors Involved in Primordia Building in Agaricus bisporus: A Review

The button mushroom Agaricus bisporus is an economically important crop worldwide. Many aspects of its cultivation are well known, except for the precise biological triggers for its fructification. By and large, for most basidiomycete species, nutrient availability, light and a drop in temperature are critical factors for fructification. A. bisporus deviates from this pattern in the sense that it does not require light for fructification. Furthermore its fructification seems to be inhibited by a self-generated factor which needs to be removed by microorganisms in order to initiate fruiting. This review explores what is known about the morphogenesis of fruiting initiation in A. bisporus, the microflora, the self-inhibitors for fruiting initiation and transcription factors involved. This information is subsequently contrasted with an overall model of the regulatory system involved in the initiation of the formation of primordia in basidiomycetes. The comparison reveals a number of the blank spots in our understanding of the fruiting process in A. bisporus.

Ultrasound enhanced production of mycelia and exopolysaccharide by Agaricus bitorquis (Quél.) Sacc. Chaidam

Agaricus bitorquis (Quél.) Sacc. Chaidam (ABSC), is a kind of rare edible macrofungi with a variety of biological ingredients, especially its polysaccharides. However, the low yield limits the popularity and promotion of rare edible macrofungi as well as its macrofungi polysaccharides. Hence, developing a positive and effective cultivation method is of great importance. Herein, an efficient ultrasonic (US) stimulation strategy was developed to improve mycelial growth and exopolysaccharides (EPS) biosynthesis from ABSC in submerged cultivation without light. A time design was employed to illustrate the effect of various process parameters including duration, starting point and times of US irradiation on ABSC productivity. 5 min US treatment for once upon ABSC after fermentation for 48 h could significantly improve EPS production and mycelia growth by above 26% and 15.03%, respectively. Furthermore, six times of 5 min US treatment could make the amount of EPS reach 218.78 ± 17.09 mg/g, which was 2.52-fold higher than that of the control. Moreover, the enhanced effect induced by US was further expounded by fermentation kinetics. Besides, the US treatment could increase mycelia permeability, change structure and reduce mycelial diameter to promote mass transfer, resulting in the improvement of EPS production and mycelia accumulation. The results demonstrated that the present proposed US intensification approach could be useful to boost up the fermentation of ABSC, which possibly applied to yield increase and fermentation product acquisition of macrofungi.

Isolation, characterization, and plant growth-promoting activities of endophytic fungi from a wild orchid Vanda cristata

Endophytism is one of the widely explored phenomena related to orchids and fungi. Endophytic fungi assist plants by supplementing nutrient acquisition, and synthesis of plant growth regulators. Vanda cristata is an epiphytic orchid that has a great diversity of endophytic fungi. Endophytic fungi were isolated from roots, stems, and leaves of V.cristata and identified by both morphological and molecular study. Furthermore, the isolated endophytic fungi were subjected to auxin synthesis, phosphate solubilization, ammonia synthesis, and elicitor growth test for understanding their growth-promoting effect in a qualitative and quantitative manner. Altogether, 12 different endophytic fungi were isolated from roots, stems, and leaves of V. cristata of which most species belonged to Ascomycota. Unidentified II fungi were found to be most effective for auxin synthesis and phosphate solubilization while Agaricus bisporous and Mycolepto discus were most effective for ammonia synthesis. We have tested the plant growth-promoting activity of the twelve isolated endophytic fungi on Cymbidium aloifolium protocorms (12 weeks old). All the endophytic fungi showed growth-promoting activity. Plant growth of Cymbidium aloifolium was found higher on the MS medium supplemented with all fungal elicitors. Fungal elicitor CVS4, however, showed the highest plant growth-promoting activity toward C. aloifolium.

Genome Survey and Transcriptome Analysis on Mycelia and Primordia of Agaricus blazei

Agaricus blazei, a type of edible straw-rotting mushroom with somewhat sweet taste and fragrance of almonds, has attracted considerable scientific and practical attention. High-throughput Illumina PE150 and PacBio RSII platform were employed to generate a genomic sequence. De novo assembly generated 36 contigs with 38,686,133 bp in size, containing 10,119 putative predicted genes. Additionally, we also studied transcriptional regulation of the mycelia and the primordia for exploration of genes involved in fruiting body formation. Expression profiling analysis revealed that 2,164 genes were upregulated in mycelia and 1,557 in primordia. Functional enrichment showed that differentially expressed genes associated with response to stress, ribosome biogenesis, arginine biosynthesis, and steroid biosynthesis pathway were more active in fruiting body. The genome and transcriptome analysis of A. blazei provide valuable sequence resources and contribute to our understanding of genes related to the biosynthesis pathway of polysaccharide and benzaldehyde, as well as the fruiting body formation.

Odorants from the Thermal Treatment of Hydrolyzed Mushroom Protein and Cysteine Enhance Saltiness Perception

Innovative approaches to develop flavors with high sensory appeal are critical in encouraging increased consumer preference and adoption of low sodium foods. Gas chromatography-olfactometry, coupled with stable isotope dilution assays and sensory experiments, led to the identification of the odorants responsible for an enhancement in saltiness perception of chicken broth prepared with thermally treated enzymatically hydrolyzed mushroom protein and cysteine, then reacted under kitchen-like cooking conditions. Comparative aroma extract dilution analysis revealed 36 odorants with flavor dilution factors between a range of 1 and 256. Sixteen odorants were quantitated and odor activity values (OAVs) calculated. Important odorants included 2-furfurylthiol (coffee, OAV 610), 1-(2-furyl)ethanethiol (meaty, OAV 78), 3-sulfanylpentan-2-one (catty, OAV 42), sotolon (maple, OAV 20), indole (animal, OAV 8), 2-methyl-3-(methyldithio)furan (meaty, OAV 3), and p-cresol (barnyard, OAV 1). An odor simulation model was evaluated in two consumer sensory studies. These studies confirmed that the addition of the aroma model increased the perceived saltiness of low sodium chicken broth (p < 0.05).

Ultrahigh-Pressure Liquid Chromatography-Quadrupole-Time-of-Flight Mass Spectrometry-Based Metabolomics Reveal the Mechanism of Methyl Jasmonate in Delaying the Deterioration of Agaricus bisporus

Conquering rapid postripeness and deterioration of Agaricus bisporus is quite challenging. We previously observed that methyl jasmonate (MeJA) pretreatment postponed the deterioration of A. bisporus, but the mechanism is unknown. Here, a nontargeted metabolomics analysis by ultrahigh-pressure liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS/MS) revealed that MeJA increased the synthesis of malate by inhibiting the decomposition of fumarate and cis-aconitate. MeJA maintained energy supply by enhancing ATP content and energy charge level and improving hexokinase and glucose-6-phosphate dehydrogenase activities as well. These results promoted ATP supply by maintaining glycolysis, the TCA cycle, and the pentose phosphate pathway. In addition, we revealed that the delayed deterioration was attributed to MeJA treatment which stimulated the energy status of A. bisporus by reducing the respiration rate and nutrient decomposition, thus maintaining energy production. Our results provide a new insight into the role of MeJA treatment in delaying deterioration of A. bisporus through ATP production and supply.

Selenium-rich mushrooms cultivation on a wheat straw substrate from seleniferous area in Punjab, India

Intensive rice-wheat cultivation cycle in Northern belt of India in general and in the State of Punjab in particular results in large volumes of straw and other post-harvest residue annually. The agricultural area, bordering the districts of Nawanshahr and Hoshiarpur, is popularly known as the seleniferous belt of India. The agri-residues, generated in seleniferous region of this state, are observed to contain significantly high concentration of selenium (Se). The present study was aimed to evaluate the Se uptake by different mushroom species: Pleurotus sajor-caju, Pleurotus ostreatus, Pleurotus citrinopileatus, Agaricus bisporus, and Volvariella volvacea, cultivated on Se-rich wheat and paddy straw from the seleniferous region. Wheat (Pleurotus species and A. bisporus) and paddy straw (V. volvacea) was inoculated with the mycelium spawn and left for 7-20 days, depending on the species, to grow. Control mushrooms were grown analogously using the agricultural residues from non-seleniferous area of the State of Punjab. All fruiting bodies were collected and analyzed in triplicate. Se was quantified using inductively coupled plasma sector field mass spectrometry. The Se accumulation was high in all species under study, being the highest in A. bisporus (1396 μg/g vs. 46.8 μg/g in controls - dry weight) and V. volvacea (231 μg/g vs. 3.77 μg/g - dry weight). The observed biological efficiency and total yield for all mushroom species showed good and unaltered productivity in Se-rich conditions, if compared to the controls. The Se-rich mushrooms can be prospective Se-supplements sourcing and biofortified foods, providing readily bioavailable and accessible Se for the diets deficient of this biologically essential element.

Boolean-chemotaxis of logibots deciphering the motions of self-propelling microorganisms

We demonstrate the feasibility of a self-propelling mushroom motor, namely a 'logibot', as a functional unit for the construction of a host of optimized binary logic gates. Emulating the chemokinesis of unicellular prokaryotes or eukaryotes, the logibots made stimuli responsive conditional movements at varied speeds towards a pair of acid-alkali triggers. A series of integrative logic operations and cascaded logic circuits, namely, AND, NAND, NOT, OR, NOR, and NIMPLY, have been constructed employing the decisive chemotactic migrations of the logibot in the presence of the pH gradient established by the sole or coupled effects of acid (HCl-catalase) and alkali (NaOH) drips inside a peroxide bath. The imposed acid and/or alkali triggers across the logibots were realized as inputs while the logic gates were functionally reconfigured to several operational modes by varying the pH of the acid-alkali inputs. The self-propelling logibot could rapidly sense the external stimuli, decide, and act on the basis of intensities of the pH triggers. The impulsive responses of the logibots towards and away from the external acid-alkali stimuli were interpreted as the potential outputs of the logic gates. The external stimuli responsive self-propulsion of the logibots following different logic gates and circuits can not only be an eco-friendly alternative to the silicon-based computing operations but also be a promising strategy for the development of intelligent pH-responsive drug delivery devices.

An Exploration into the Bacterial Community under Different Pasteurization Conditions during Substrate Preparation (Composting-Phase II) for Agaricus bisporus Cultivation

Substrate preparation (i.e., composting) for Agaricus bisporus cultivation is the most critical point of mushroom production. Among many factors involved in the composting process, the microbial ecology of the system is the underlying drive of composting and can be influenced by composting management techniques. Pasteurization temperature at the beginning of phase II, in theory, may influence the bacterial community and subsequently the "selectivity" and nutrition of the final substrate. Therefore, this hypothesis was tested by simulation in bioreactors under different pasteurization conditions (57 °C/6 h, 60 °C/2 h, and 68 °C/2 h), simulating conditions adopted by many producers. Bacterial diversity, based on 16S ribosomal RNA obtained by high-throughput sequencing and classified in operational taxonomic units (OTUs), was greater than previously reported using culture-dependent methods. Alpha diversity estimators show a lower diversity of OTUs under a high-temperature pasteurization condition. Bacillales order shows a relatively higher OTU abundance under a high-pasteurization temperature, which also was related to high ammonia emission measurements. On the other hand, beta diversity analysis showed no significantly changes in the bacterial community structure under different conditions. Agaricus bisporus mycelium growth during a standard spawn run period was significantly slower in the compost pasteurized at high temperature. Since the bacterial community structure was not greatly affected by different pasteurization conditions but by-products left (e.g., ammonia) at the end of compost conditioning varied, further studies need to be conducted to determine the functional role of the microbial communities found during substrate preparation for Agaricus bisporus cultivation.

Liquid chromatography-mass spectrometry method for evaluating the dissipation dynamics of cyromazine and its metabolite in Agaricus bisporus and dietary risk assessment

Providing guidance on the reasonable use of pesticide in agricultural production is of particular importance for ensuring food safety. In the present study, a field trial was performed to study the dissipation and accumulative pattern of cyromazine (CA) and its metabolite in Agaricus bisporus (A. bisporus) cultivation. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was first developed and validated for the determination of CA and melamine (MEL) in the casing soil and fruiting body. During the cultivation period, the dissipation rates of CA in the casing soil were between 51.57 and 63.48% at three dose groups. The fruiting body presented higher accumulation ability for MEL compared with CA. The terminal residues of MEL never exceeded the maximum residue limits (MRLs) in food. In addition, the intake health risk from the CA and MEL residues in the fruiting body were negligible to humans. This study will help to provide valuable guidance on the application strategies of CA in A. bisporus cultivation.

Remediation capacity of Cd and Pb ions by mycelia of Imleria badia, Laetiporus sulphureus, and Agaricus bisporus in vitro cultures

The goal of this study was to evaluate cadmium and lead accumulation ability of in vitro cultures biomass containing selected edible mushroom species derived from the environment (Laetiporus sulphureus, Imleria badia) and those of commercial origin (Agaricus bisporus). Atomic absorption spectrometry was used to evaluate the content of Cd(II) and Pb(II) on the medium supplemented with Cd(II) or Pb(II), each of them at the same concentration of 5·10^-5 M. The highest concentration of Cd(II) ions was determined in the biomass from L. sulphureus in vitro cultures, while the highest concentration of Pb(II) ions was found in the biomass from A. bisporus in vitro cultures. The greatest Cd(II) and Pb(II) accumulation ability in mycelium per dry weight was shown for L. sulphureus. Among the test species, biomass of A. bisporus showed the lowest ability for the bioaccumulation of Cd(II); however, comparable ability for the remediation of Pb(II) was provided by the biomasses from A. bisporus and I. badia in vitro cultures. The results confirm the possibility of using these mushroom species for remediation and indicate the relationship between bioaccumulation of heavy metals and the test species.

Regulation of Respiratory Pathway and Electron Transport Chain in Relation to Senescence of Postharvest White Mushroom (Agaricus bisporus) under High O2/CO2 Controlled Atmospheres

In order to study the respiration metabolism mechanism based on the generation of adenosine triphosphate (ATP) and reactive oxygen species (ROS) and nitric oxide (NO) by the electron transport chain (ETC) of the white mushroom under high O₂/CO₂ controlled atmospheres, the treatments of 100% O₂, 80% O₂ + 20% CO₂, 60% O₂ + 40% CO₂, and 40% O₂ + 60% CO₂ at 2 ± 1 °C were employed and natural air was used as the control. ATP and energy charge can maintain the membrane integrity and function, life activities, and physicochemical reactions of higher plants. The results showed that the 80% O₂ + 20% CO₂ treatment inhibited the respiration rate, embden-meyerhof-parnas or glycolysis pathway, and ROS and NO contents. It significantly delayed the reduction of the ATP content and energy charge level, tricarboxyfic-acid-cycle and cytochrome pathway proportion, and their key enzymes activity and gene expression. It also maintained a high phosphopentose pathway and moderate alternative pathway. Results indicated that the 80% O₂ + 20% CO₂ prolonged the storage time of mushrooms to 24 days and retarded the senescence through retaining the higher energy, suppressing the ROS contents, enhancing the endurance capability in adversity, and regulating the respiration pathways and ETC metabolism.

Characterization of three pyranose dehydrogenase isoforms from the litter-decomposing basidiomycete Leucoagaricus meleagris (syn. Agaricus meleagris)

Multigenicity is commonly found in fungal enzyme systems, with the purpose of functional compensation upon deficiency of one of its members or leading to enzyme isoforms with new functionalities through gene diversification. Three genes of the flavin-dependent glucose-methanol-choline (GMC) oxidoreductase pyranose dehydrogenase (AmPDH) were previously identified in the litter-degrading fungus Agaricus (Leucoagaricus) meleagris, of which only AmPDH1 was successfully expressed and characterized. The aim of this work was to study the biophysical and biochemical properties of AmPDH2 and AmPDH3 and compare them with those of AmPDH1. AmPDH1, AmPDH2 and AmPDH3 showed negligible oxygen reactivity and possess a covalently tethered FAD cofactor. All three isoforms can oxidise a range of different monosaccarides and oligosaccharides including glucose, mannose, galactose and xylose, which are the main constituent sugars of cellulose and hemicelluloses, and judging from the apparent steady-state kinetics determined for these sugars, the three isoforms do not show significant differences pertaining to their reaction with sugar substrates. They oxidize glucose both at C2 and C3 and upon prolonged reaction C2 and C3 double-oxidized glucose is obtained, confirming that the A. meleagris genes pdh2 (AY753308.1) and pdh3 (DQ117577.1) indeed encode CAZy class AA3_2 pyranose dehydrogenases. While reactivity with electron donor substrates was comparable for the three AmPDH isoforms, their kinetic properties differed significantly for the model electron acceptor substrates tested, a radical (the 2,2'-azino-bis[3-ethylbenzothiazoline-6-sulphonic acid] cation radical), a quinone (benzoquinone) and a complexed iron ion (the ferricenium ion). Thus, a possible explanation for this PDH multiplicity in A. meleagris could be that different isoforms react preferentially with structurally different electron acceptors in vivo.

[The development of Agaricus bisporus wet bubble disease and the nuclear phase of pathogen]

OBJECTIVE

We studied the dynamic nuclear behavior of Hypomyces perniciosus on axenic culture and its disease progression after infection on different growth stages of Agaricus bisporus.

METHODS

Infection process was initiated by inoculating different stages of A. bisporus fruit body, and different depths of compost and casing soil with H. perniciosus. Disease progression was studied by observing symptoms on the fruit body using light microscopy and scanning electron microscopy. The nuclear behavior of H. perniciosus was determined by observation using fluorescence light microscopy after binding of DNA specific fluorochrome dye (DAPI:4, 6-Diamidino-2-phenylindole dihydrochloride) to the nuclei.

RESULTS

Inoculating H. perniciosus on different depths of compost and casing soil resulted in different disease rate as follows:on the surface of casing soil>in the center of casing soil>between the casing soil and the compost>in the center of compost. H. perniciosus can infect any stage of fruit body development, when young primordial (up to 3 mm) was infected, large, irregular and tumorous fungal masses were formed. H. perniciosus directly penetrated A. bisporus without the formation of appressorium-like structures. The germination of the conidia led to a necrotic brown lesion symptom on A. bisporus at the beginning stages of disease development. The mycelium of A. bisporus plasmolysed, hydropically degenerated, cytoplasmolysed, emptied of mycelium cytosol and eventual death as the disease advanced. H. perniciosus produced two types of conidia. Group I conidia had no septa, colorless and smooth containing one nucleus. Group II didymoconidium had septa, containing two nuclei, separated by septa. The first round of mitosis occurred in conidia with no nucleus in the germinal tube. Another kind of asexual spore for thicker cell wall wart convex chlamydospore, chlamydospore had two cells. The upper cell had two nuclear while the basal cell had one or two nuclear, when germinated, it produced one or two germinal tubes. The number of nuclear in the germinal tube was irregular, usually contained 0 to 2 nuclear.

CONCLUSION

H. perniciosus can infect any part of the A. bisporus fruit body and can cause tremendous cytology changed. If we perform single spore isolation to do genetic analysis, one must isolate conidia with no septa.

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.

The Agaricus blazei-Based Mushroom Extract, Andosan™, Protects against Intestinal Tumorigenesis in the A/J Min/+ Mouse

Background

The novel A/J Min/+ mouse, which is a model for human Familial Adenomatous Polyposis (FAP), develops spontaneously multiple adenocarcinomas in the colon as well as in the small intestine. Agaricus blazei Murill (AbM) is an edible Basidiomycetes mushroom that has been used in traditional medicine against cancer and other diseases. The mushroom contains immunomodulating β-glucans and is shown to have antitumor effects in murine cancer models. Andosan^™ is a water extract based on AbM (82%), but it also contains the medicinal Basidiomycetes mushrooms Hericeum erinaceus and Grifola frondosa.

Methods and findings

Tap water with 10% Andosan^™ was provided as the only drinking water for 15 or 22 weeks to A/J Min/+ mice and A/J wild-type mice (one single-nucleotide polymorphism (SNP) difference), which then were exsanguinated and their intestines preserved in formaldehyde and the serum frozen. The intestines were examined blindly by microscopy and also stained for the tumor-associated protease, legumain. Serum cytokines (pro- and anti-inflammatory, Th1-, Th2 -and Th17 type) were measured by Luminex multiplex analysis. Andosan^™ treated A/J Min/+ mice had a significantly lower number of adenocarcinomas in the intestines, as well as a 60% significantly reduced intestinal tumor load (number of tumors x size) compared to control. There was also reduced legumain expression in intestines from Andosan^™ treated animals. Moreover, Andosan^™ had a significant cytotoxic effect correlating with apoptosis on the human cancer colon cell line, Caco-2, in vitro. When examining serum from both A/J Min/+ and wild type mice, there was a significant increase in anti-tumor Th1 type and pro-inflammatory cytokines in the Andosan^™ treated mice.

Conclusions

The results from this mouse model for colorectal cancer shows significant protection of orally administered Andosan^™ against development of intestinal cancer. This is supported by the finding of less legumain in intestines of Andosan^™ treated mice and increased systemic Th1 cytokine response. The mechanism is probably both immuno-modulatory and growth inhibition of tumor cells by induction of apoptosis.

Inhibitory mechanisms of glabridin on tyrosinase

Tyrosinase is an oxidase that is the rate-limiting enzyme for controlling the production of melanin in the human body. Overproduction of melanin could lead to a variety of skin disorders. Glabridin, an isoflavan, isolated from the root of Glycyrrhiza glabra Linn, has exhibited several pharmacological activities, including excellent inhibitory effects on tyrosinase. In this paper, the inhibitory kinetics of glabridin on tyrosinase and their binding mechanisms were determined using spectroscopic, zebrafish model and molecular docking techniques. The results indicate that glabridin reversibly inhibits tyrosinase in a noncompetitive manner through a multiphase kinetic process with the IC50 of 0.43μmol/L. It has been shown that glabridin had a strong ability to quench the intrinsic fluorescence of tyrosinase mainly through a static quenching procedure, suggesting a stable glabridin-tyrosinase complex may be generated. The results of molecular docking suggest that glabridin did not directly bind to the active site of tyrosinase. Moreover, according to the results of zebrafish model system, glabridin shows no effects on melanin synthesis in zebrafish but presents toxicity to zebrafish embryo. The possible inhibitory mechanisms, which will help to design and search for tyrosinase inhibitors especially for glabridin analogues, were proposed.

Effect of supplementing crop substrate with defatted pistachio meal on Agaricus bisporus and Pleurotus ostreatus production

BACKGROUND

This work assesses the agronomic performance of defatted pistachio meal, after oil extraction, as a nutritional substrate supplement when growing the mushroom species Agaricus bisporus (Lange) Imbach and Pleurotus ostreatus (Jacq.) P. Kumm. Materials were applied at different doses at spawning. Along with non-supplemented substrates, commercial nutritional supplements were used as controls. Proximate analysis of mushrooms is also considered.

RESULTS

For the cultivation of champignon, defatted pistachio meal has provided larger mushrooms (unitary weight and cap diameter) with firmer texture and greater content in dry weight and protein, without significant alterations in quantitative parameters. For Pleurotus ostreatus, the supplement led to significant yield increase, even providing up to 34.4% of increment compared to non-supplementation with meal, reaching a biological efficiency of 129.9 kg dt(-1) , when applied to the 15 g kg(-1) compost dose. Supplementation has also been conducted to increase dry weight, protein and fibre within carpophores and to decrease the energy value. Defatted pistachio meal has similar or better results compared to the commercial supplements used as reference.

CONCLUSIONS

Compost supplementation with defatted pistachio meal in A. bisporus concerns mainly the quantitative parameters (size, texture, dry weight and protein). Based on the results obtained, this technique has greater potential of development for P. ostreatus commercial crops, basically due to expected increases in production, with a direct impact on benefits and crop profitability. © 2015 Society of Chemical Industry.

Bioremediation of multi-polluted soil by spent mushroom (Agaricus bisporus) substrate: Polycyclic aromatic hydrocarbons degradation and Pb availability

This study investigates the effect of three spent Agaricus bisporus substrate (SAS) application methods on bioremediation of soil multi-polluted with Pb and PAH from close to a shooting range with respect natural attenuation (SM). The remediation treatments involve (i) use of sterilized SAS to biostimulate the inherent soil microbiota (SSAS) and two bioaugmentation possibilities (ii) its use without previous treatment to inoculate A. bisporus and inherent microbiota (SAS) or (iii) SAS sterilization and further A. bisporus re-inoculation (Abisp). The efficiency of each bioremediation microcosm was evaluated by: fungal activity, heterotrophic and PAH-degrading bacterial population, PAH removal, Pb mobility and soil eco-toxicity. Biostimulation of the native soil microbiology (SSAS) achieved similar levels of PAH biodegradation as SM and poor soil detoxification. Bioaugmented microcosms produced higher PAH removal and eco-toxicity reduction via different routes. SAS increased the PAH-degrading bacterial population, but lowered fungal activity. Abisp was a good inoculum carrier for A. bisporus exhibiting high levels of ligninolytic activity, the total and PAH-degrading bacteria population increased with incubation time. The three SAS applications produced slight Pb mobilization (<0.3%). SAS sterilization and further A. bisporus re-inoculation (Abisp) proved the best application method to remove PAH, mainly BaP, and detoxify the multi-polluted soil.

Induction of lcc2 expression and activity by Agaricus bisporus provides defence against Trichoderma aggressivum toxic extracts

Laccases are used by fungi for several functions including defence responses to stresses associated with attack by other fungi. Laccase activity changes and the induction of two laccase genes, lcc1 and lcc2, in Agaricus bisporus were measured in response to toxic extracts of medium in which Trichoderma aggressivum, the cause of green mould disease, was grown. A strain of A. bisporus that shows resistance to the extracts showed higher basal levels and greater enzymatic activity after extract exposure than did a sensitive strain. Furthermore, pre-incubation of T. aggressivum extract with laccases reduced toxicity. Faster induction and greater numbers of lcc2 transcripts in response to the extract were noted in the resistant strain than in the sensitive strain. The timing and increase in lcc2 transcript abundance mirrored changes in total laccase activity. No correlation between resistance and lcc1 transcription was apparent. Transcript abundance in transformants with a siRNA construct homologous to both genes varied widely. A strong negative correlation between transcript abundance and sensitivity of the transformant to toxic extract was observed in plate assays. These results indicated that laccase activity and in particular that encoded by lcc2 contributes to toxin metabolism and by extension green mould disease resistance.

Fate of Carbohydrates and Lignin during Composting and Mycelium Growth of Agaricus bisporus on Wheat Straw Based Compost

In wheat straw based composting, enabling growth of Agaricus bisporus mushrooms, it is unknown to which extent the carbohydrate-lignin matrix changes and how much is metabolized. In this paper we report yields and remaining structures of the major components. During the Phase II of composting 50% of both xylan and cellulose were metabolized by microbial activity, while lignin structures were unaltered. During A. bisporus’ mycelium growth (Phase III) carbohydrates were only slightly consumed and xylan was found to be partially degraded. At the same time, lignin was metabolized for 45% based on pyrolysis GC/MS. Remaining lignin was found to be modified by an increase in the ratio of syringyl (S) to guaiacyl (G) units from 0.5 to 0.7 during mycelium growth, while fewer decorations on the phenolic skeleton of both S and G units remained.

Dose-Response Effect of Sunlight on Vitamin D2 Production in Agaricus bisporus Mushrooms

The dose response effect of UV-B irradiation from sunlight on vitamin D2 content of sliced Agaricus bisporus (white button mushroom) during the process of sun-drying was investigated.Real-time UV-B and UV-A data were obtained using a high-performance spectroradiometer. During the first hour of sunlight exposure, the vitamin D2 content of the mushrooms increased in a linear manner, with concentrations increasing from 0.1 μg/g up to 3.9 ± 0.8 μg/g dry weight (DW). At the subsequent two measurements one and 3 h later, respectively, a plateau was reached. Two hours of additional exposure triggered a significant decline in vitamin D2 content. After just 15 min of sun exposure and an UV-B dose of 0.13 J/cm(2), the vitamin D2 content increased significantly to 2.2 ± 0.5 μg/g DW (P < 0.0001), which is equivalent to 17.6 μg (704 IU) vitamin D2 per 100 g of fresh mushrooms and comparable to levels found in fatty fish like the Atlantic salmon.

Implications of polluted soil biostimulation and bioaugmentation with spent mushroom substrate (Agaricus bisporus) on the microbial community and polycyclic aromatic hydrocarbons biodegradation

Different applications of spent Agaricus bisporus substrate (SAS), a widespread agro-industrial waste, were investigated with respect to the remediation of a historically polluted soil with Polycyclic Aromatic Hydrocarbons (PAH). In one treatment, the waste was sterilized (SSAS) prior to its application in order to assess its ability to biostimulate, as an organic amendment, the resident soil microbiota and ensuing contaminant degradation. For the other treatments, two bioaugmentation approaches were investigated; the first involved the use of the waste itself and thus implied the application of A. bisporus and the inherent microbiota of the waste. In the second treatment, SAS was sterilized and inoculated again with the fungus to assess its ability to act as a fungal carrier. All these treatments were compared with natural attenuation in terms of their impact on soil heterotrophic and PAH-degrading bacteria, fungal growth, biodiversity of soil microbiota and ability to affect PAH bioavailability and ensuing degradation and detoxification. Results clearly showed that historically PAH contaminated soil was not amenable to natural attenuation. Conversely, the addition of sterilized spent A. bisporus substrate to the soil stimulated resident soil bacteria with ensuing high removals of 3-ring PAH. Both augmentation treatments were more effective in removing highly condensed PAH, some of which known to possess a significant carcinogenic activity. Regardless of the mode of application, the present results strongly support the adequacy of SAS for environmental remediation purposes and open the way to an attractive recycling option of this waste.

Uptake and transformation of arsenic during the vegetative life stage of terrestrial fungi

Many species of terrestrial fungi produce fruiting bodies that contain high proportions of arsenobetaine (AB), an arsenic compound of no known toxicity. It is unknown whether fungi produce or accumulate AB from the surrounding environment. The present study targets the vegetative life stage (mycelium) of fungi, to examine the role of this stage in arsenic transformations and potential formation of AB. The mycelia of three different fungi species were cultured axenically and exposed to AB, arsenate (As(V)) and dimethylarsinoyl acetic acid for 60 days. Agaricus bisporus was additionally exposed to hypothesized precursors for AB and the exposure time to As(V) and dimethlyarsinic acid was also extended to 120 days. The mycelia of all fungi species accumulated all arsenic compounds with two species accumulating significantly more AB than other compounds. Few biotransformations were observed in these experiments indicating that it is unlikely that the mycelium of the fungus is responsible for biosynthesizing AB.

The protective effect of Agaricus blazei Murrill, submerged culture using the optimized medium composition, on alcohol-induced liver injury

Agaricus blazei Murrill (ABM), an edible mushroom native to Brazil, is widely used for nonprescript and medicinal purposes. Alcohol liver disease (ALD) is considered as a leading cause for a liver injury in modern dietary life, which can be developed by a prolonged or large intake of alcohol. In this study, the medium composition of ABM was optimized using response surface methodology for maximum mycelial biomass and extracellular polysaccharide (EPS) production. The model predicts to gain a maximal mycelial biomass and extracellular polysaccharide at 1.047 g/100 mL, and 0.367 g/100 mL, respectively, when the potato is 29.88 g/100 mL, the glucose is 1.01 g/100 mL, and the bran is 1.02 g/100 mL. The verified experiments showed that the model was significantly consistent with the model prediction and that the trends of mycelial biomass and extracellular polysaccharide were predicted by artificial neural network. After that, the optimized medium was used for the submerged culture of ABM. Then, alcohol-induced liver injury in mice model was used to examine the protective effect of ABM cultured using the optimized medium on the liver. And the hepatic histopathological observations showed that ABM had a relatively significant role in mice model, which had alcoholic liver damage.

Structural characterization of a water-soluble polysaccharide from the fruiting bodies of Agaricus bisporus

An edible fungal polysaccharide termed as ABP was obtained by extraction with hot water, and followed successive chromatographic purification using DEAE-Sepharose Fast Flow column and Sephacryl S-300 High-Resolution column. A symmetrical peak was obtained on high-performance size-exclusion chromatography with an average molecular weight of 5.17 × 104 Da, which was named ABP, and its main components were D-glucose and D-mannose. Based on the study of methylation analysis, along with FT-IR, GC, GC-MS, 1D 1H and 13C NMR and 2D NMR (H-HCOSY, TOCSY, HMQC, and NOESY), its chemical structure was featured with a repeating unit (1→6) linking β-D-Glcp as the main backbone with (1→4)-linked α-D-Manp units. The structure of the mainly repeating units of ABP was established as: →6)-β-D-Glcp-(1→4)-α-D-Manp(1→6)-β-D-Glcp-(1→6)-β-D-Glcp-(1→.

[Antiviral properties of basidiomycetes metabolites]

The data on the antiviral action of the Ganoderma lucidum, Lentinus edodes, Grifola frondosa, Agaricus brasiliensis and other basidiomycetes metabolites are summurized. The metabolites of these species of basidiomycetes exhibit a direct antiviral effect on herpes simplex virus types I and II, human immunodeficiency virus (HIV), hepatitis B virus, vesicular stomatitis virus, influenza virus, Epstein-Barr virus, and others. Moreover, metabolites of basidiomycetes increased antiviral immunity.

Cadmium and lead bioavailability and their effects on polycyclic aromatic hydrocarbons biodegradation by spent mushroom substrate

Bioremediation of mixed metal-organic soil pollution constitutes a difficult task in different ecosystems all around the world. The aims of this work are to determine the capacity of two spent mushroom substrates (Agaricus bisporus and Pleurotus ostreatus) to immobilize Cd and Pb, to assess the effect of these metals on laccase activity, and to determine the potential of spent A. bisporus substrate to biodegrade four polycyclic aromatic hydrocarbons (PAH): fluorene, phenanthrene, anthracene, and pyrene, when those toxic heavy metals Cd and Pb are present. According to adsorption isotherms, spent P. ostreatus and A. bisporus substrates showed a high Pb and Cd adsorption capacity. Pb and Cd interactions with crude laccase enzyme extracts from spent P. ostreatus and A. bisporus substrates showed Cd and Pb enzyme inhibition; however, laccase activity of A. bisporus presented lower inhibition. Spent A. bisporus substrate polluted with PAH and Cd or Pb was able to biodegrade PAH, although both metals decrease the biodegradation rate. Spent A. bisporus substrate contained a microbiological consortium able to oxidize PAH with high ionization potential. Cd and Pb were immobilized during the bioremediation process by spent A. bisporus substrate. Consequently, spent A. bisporus substrate was adequate as a multi-polluted soil bioremediator.

Packed bed column studies on lead(II) removal from industrial wastewater by modified Agaricus bisporus

Agaricus bisporus showed best performance in removing Pb(II) with a biosorption capacity of 86.4 mg g(-1) after modification with NaOH. In this work, the removal of Pb(II) from wastewater has been conducted in column mode. The metal removal was dependent on the flow rate, initial metal concentration, and bed height. The experimental data obtained from the biosorption process was successfully correlated with the Bohart-Adams, Thomas, and Yoon-Nelson models. Five biosorption-desorption cycles yielded 95.34%, 92.27%, 90.13%, 86.75%, and 81.52% regeneration, respectively. Pb(II) could be effectively removed from industrial wastewater; some metal ions and organics were also removed concomitantly, and the obtained effluent had characteristics of better quality. The results confirmed that modified A. bisporus could be applied for the removal of heavy metals from industrial wastewater in a continuous column process.

Carbohydrate utilization and metabolism is highly differentiated in Agaricus bisporus

BACKGROUND

Agaricus bisporus is commercially grown on compost, in which the available carbon sources consist mainly of plant-derived polysaccharides that are built out of various different constituent monosaccharides. The major constituent monosaccharides of these polysaccharides are glucose, xylose, and arabinose, while smaller amounts of galactose, glucuronic acid, rhamnose and mannose are also present.

RESULTS

In this study, genes encoding putative enzymes from carbon metabolism were identified and their expression was studied in different growth stages of A. bisporus. We correlated the expression of genes encoding plant and fungal polysaccharide modifying enzymes identified in the A. bisporus genome to the soluble carbohydrates and the composition of mycelium grown compost, casing layer and fruiting bodies.

CONCLUSIONS

The compost grown vegetative mycelium of A. bisporus consumes a wide variety of monosaccharides. However, in fruiting bodies only hexose catabolism occurs, and no accumulation of other sugars was observed. This suggests that only hexoses or their conversion products are transported from the vegetative mycelium to the fruiting body, while the other sugars likely provide energy for growth and maintenance of the vegetative mycelium. Clear correlations were found between expression of the genes and composition of carbohydrates. Genes encoding plant cell wall polysaccharide degrading enzymes were mainly expressed in compost-grown mycelium, and largely absent in fruiting bodies. In contrast, genes encoding fungal cell wall polysaccharide modifying enzymes were expressed in both fruiting bodies and vegetative mycelium, but different gene sets were expressed in these samples.

Main phenolic compounds of the melanin biosynthesis pathway in bruising-tolerant and bruising-sensitive button mushroom (Agaricus bisporus) strains

Browning is one of the most common postharvest changes in button mushrooms, which often results in economic losses. Phenolic compounds, which are associated with browning, were extracted from the nonbruised and bruised skin tissue of various button mushrooms with a sulfite-containing solution and analyzed with UHPLC-PDA-MS. In total, 34 phenolic compounds were detected. Only small differences in the total phenolic content between bruising-tolerant and -sensitive strains were observed. The contents of γ-L-glutaminyl-4-hydroxybenzene (GHB) and γ-L-glutaminyl-3,4-dihydroxybenzene (GDHB) correlated with bruising sensitivity; for example, R(2) values of 0.85 and 0.98 were found for nonbruised brown strains, respectively. In nonbruised skin tissue of the strains with brown caps, the GHB and GDHB contents in sensitive strains were on average 20 and 15 times higher, respectively, than in tolerant strains. GHB and GDHB likely participate in the formation of brown GHB-melanin, which seemed to be the predominant pathway in bruising-related discoloration of button mushrooms.

Anaerobically digested food waste in compost for Agaricus bisporus and Agaricus subrufescens and its effect on mushroom productivity

BACKGROUND

Source-separated food waste is increasingly being treated by means of hygienisation followed by anaerobic digestion. The fibrous digester residue (digestate) is a potential mushroom substrate, while heat from the biogas can provide steam for the cultivation process. Using bag experiments the present study explored digestate as a full substitute for chicken manure conventionally used in mushroom composts.

RESULTS

After mixing, a rapid temperature development in the compost was stimulated by a small amount of chicken manure, as aerobic microbial seeding. Mechanical elimination of lumps was essential for full mycelial colonisation. Three straw digestate composts had Agaricus bisporus mushroom yields above 370 g kg⁻¹ substrate. The optimal compost water content was 600 g kg⁻¹ at inoculation, and high digestate content (up to 500 g kg⁻¹ by dry weight) did not affect yield for this species. High yields of A. subrufescens (200 g kg⁻¹) were related to drier composts of lower digestate content (more straw) and lower pH values at inoculation.

CONCLUSION

Digestate successfully substituted chicken manure in straw composts without affecting mushroom yields for both species. There were no clear differences between straw digestate and control composts in terms of mushroom dry matter, size, nitrogen or ash content.

Changes in reactive oxygen species production and antioxidant enzyme activity of Agaricus bisporus harvested at different stages of maturity

BACKGROUND

The edible mushroom Agaricus bisporus is more prone to senescence than most other vegetables. However, the senescence of A. bisporus before harvesting is often ignored. In this study the changes in reactive oxygen species (ROS) production and antioxidant enzyme activity of A. bisporus harvested at four different stages of maturity were investigated.

RESULTS

The firmness of A. bisporus decreased from 6.22 to 5.12 N. Respiration rate increased from 540.65 to 609.82 mg CO2 kg⁻¹ fresh weight (FW) h⁻¹. Browning degree increased from 0.42 to 0.71, showing a positive correlation with polyphenol oxidase activity. For ROS production, superoxide radical production rate increased from 0.51 to 1.16 nmol g⁻¹ FW s⁻¹. Hydrogen peroxide content increased from 0.81 to 1.39 nmol g⁻¹ FW and then decreased rapidly to 0.68 nmol g⁻¹ FW. Malondialdehyde content increased from 1.58 to 2.64 nmol g⁻¹ FW. For antioxidant enzymes, superoxide dismutase and peroxidase activities decreased significantly at stage 4, whereas a significant increase in catalase activity was found at stages 3 and 4.

CONCLUSIONS

The balance between ROS and antioxidants was destroyed at stage 4, causing extensive senescence of mushroom tissues. Thus A. bisporus should be harvested at stage 3.

Chemical characterisation and speciation of organic selenium in cultivated selenium-enriched Agaricus bisporus

The selenium concentration in Agaricus bisporus cultivated in growth compost irrigated with sodium selenite solution increased by 28- and 43-fold compared to the control mushroom irrigated solely with water. Selenium contents of mushroom proteins increased from 13.8 to 60.1 and 14.1 to 137 μgSe/g in caps and stalks from control and selenised mushrooms, respectively. Selenocystine (SeCys; detected as [SeCys]2 dimer), selenomethionine (SeMet), and methyl-selenocysteine (MeSeCys) were separated, identified and quantified by liquid chromatography-electrospray ionisation-mass spectrometry from water solubilised and acetone precipitated proteins, and significant increases were observed for the selenised mushrooms. The maximum selenoamino acids concentration in caps and stalks of control/selenised mushrooms was 4.16/9.65 μg/g dried weight (DW) for SeCys, 0.08/0.58 μg/g DW for SeMet, and 0.031/0.10 μg/g DW for MeSeCys, respectively. The most notable result was the much higher levels of SeCys accumulated by A. bisporus compared to SeMet and MeSeCys, for both control and selenised A. bisporus.

Capacity for colonization and degradation of horse manure and wheat-straw-based compost by different strains of Agaricus subrufescens during the first two weeks of cultivation

The potential of Agaricus subrufescens strains to colonize and transform horse manure and wheat-straw-based mushroom compost under the physico-chemical conditions typically used for Agaricus bisporus was assessed. Lignocellulolytic activities, H2O2 production and substrate transformation (assessed via CP/MAS NMR of (13)C) for certain A. subrufescens strains were similar or even greater than those obtained for an A. bisporus strain used as control. Moreover, the functional diversity of the microbial communities of the substrate was not altered by the growth of A. subrufescens after 2weeks. These findings obtained with mesocosms simulating the incubation phase of the mushroom production process hold promise for the improvement of cultivation of this tropical Agaricus species on European standard mushroom compost.

The 1.6 Å crystal structure of pyranose dehydrogenase from Agaricus meleagris rationalizes substrate specificity and reveals a flavin intermediate

Pyranose dehydrogenases (PDHs) are extracellular flavin-dependent oxidoreductases secreted by litter-decomposing fungi with a role in natural recycling of plant matter. All major monosaccharides in lignocellulose are oxidized by PDH at comparable yields and efficiencies. Oxidation takes place as single-oxidation or sequential double-oxidation reactions of the carbohydrates, resulting in sugar derivatives oxidized primarily at C2, C3 or C2/3 with the concomitant reduction of the flavin. A suitable electron acceptor then reoxidizes the reduced flavin. Whereas oxygen is a poor electron acceptor for PDH, several alternative acceptors, e.g., quinone compounds, naturally present during lignocellulose degradation, can be used. We have determined the 1.6-Å crystal structure of PDH from Agaricus meleagris. Interestingly, the flavin ring in PDH is modified by a covalent mono- or di-atomic species at the C(4a) position. Under normal conditions, PDH is not oxidized by oxygen; however, the related enzyme pyranose 2-oxidase (P2O) activates oxygen by a mechanism that proceeds via a covalent flavin C(4a)-hydroperoxide intermediate. Although the flavin C(4a) adduct is common in monooxygenases, it is unusual for flavoprotein oxidases, and it has been proposed that formation of the intermediate would be unfavorable in these oxidases. Thus, the flavin adduct in PDH not only shows that the adduct can be favorably accommodated in the active site, but also provides important details regarding the structural, spatial and physicochemical requirements for formation of this flavin intermediate in related oxidases. Extensive in silico modeling of carbohydrates in the PDH active site allowed us to rationalize the previously reported patterns of substrate specificity and regioselectivity. To evaluate the regioselectivity of D-glucose oxidation, reduction experiments were performed using fluorinated glucose. PDH was rapidly reduced by 3-fluorinated glucose, which has the C2 position accessible for oxidation, whereas 2-fluorinated glucose performed poorly (C3 accessible), indicating that the glucose C2 position is the primary site of attack.

Evaluation of the individuality of white rot macro fungus for the decolorization of synthetic dye

INTRODUCTION

A biosorbent was developed by simple dried Agaricus bisporus (SDAB) and effectively used for the biosorption of cationic dyes, Crystal Violet and Brilliant Green.

MATERIALS AND METHODS

For the evaluation of the biosorbent system, all the batch equilibrium parameters like pH, biomass dose, contact time, and temperature were optimized to determine the decolorization efficiency of the biosorbent. The maximum yields of dye removal were achieved at pH 4.0 for Crystal Violet (CV) and pH 5.0 for Brilliant Green (BG), which are closer to their natural pH also.

RESULT AND DISCUSSION

Equilibrium was established at 60 and 40 min for CV and BG, respectively. Pseudo first-order, pseudo second-order, and intraparticle-diffusion kinetic models were studied at different temperatures. Isotherm models such as Freundlich, Langmuir, and Dubinin-Radushkevich were also studied. Biosorption processes were successfully described by Langmuir isotherm model and the pseudo second-order kinetic model.

CONCLUSIONS

The biosorption capacity of A. bisporus over CV and BG were found as 21.74 and 12.16 mg gm(-1). Thermodynamic parameters indicated that the CV and BG dye adsorption onto A. bisporus is spontaneous and exothermic in the single and ternary systems. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used for the surface morphology, crystalline structure of biosorbent, and dye-biosorbent interaction, respectively. This analysis of the biosorption data confirmed that these biosorption processes are ecofriendly and economical. Thus, this biomass system may be useful for the removal of contaminating cationic dyes.