Edible Mushroom Pleurotus Ostreatus Research Articles

Structure Analysis of the MatA Locus of Sexual Compatibility in the Edible Mushroom Pleurotus ostreatus

The edible oyster mushroom Pleurotus ostreatus is one of the most cultivated species worldwide. Morphogenesis associated with the maturation of fruit bodies is controlled by two unlinked loci of sexual compatibility matA and matB with multiple alleles (tetrapolar system of sexual compatibility). Quantitative analysis of the alleles of mating compatibility loci in 17 natural isolates collected in the Moscow region was performed in mon–mon (monokaryons–monokaryon) and di–mon (dikaryon–monokaryon) crossings. Four monokaryotic testers strains which were heteroallelic at both mating type loci were obtained for each of the five natural mushroom isolates by using original technique of sterile spore prints on Petri dishes and mon–mon crossing. Twelve natural isolates were crossed via di-mon mating with the four monokaryotic testers M-38. Genetic analysis of the alleles of sexual compatibility loci in 17 natural isolates revealed multiple alleles at both loci: at least ten alleles at matA locus and eight alleles at matB locus. Structural organization analysis of the matA locus was performed in silico for homokaryotic strains PC9 and PC15 based on the whole-genome sequencing data available at DOE Joint Genome Institute. The matA locus has an extremely divergent structure: there are one copy of the homeodomain gene hd1 and one copy of the hd2 gene in the PC9 strain, whereas the matA locus of the PC15 strain is composed by two copies of hd1.1 and hd1.2 genes (class HD1 homeodomain proteins) and one copy of hd2 gene (class HD2 proteins). Comprehensive analysis of amino acid sequences of HD1 and HD2 homeodomain proteins demonstrated that the proteins have a globular structure with the nuclear localization and contain a variable N-terminus and a more conserved DNA-binding domain with a specific conserved motif WFXNXR in the third ɑ-helix. The results suggest that multiple alleles of the matA locus of sexual compatibility in basidiomycete fungi is achieved due to both different copy number of the coding hd genes within the locus and the variability of the coding gene sequences.

The use of rice husk in the substrate composition increases Pleurotus ostreatus mushroom production and quality

Rice husk is a waste generated in large quantities in various countries, although its reuse is limited due to low nutritional quality and high silica content. Therefore, this study sought to evaluate using raw or carbonized rice husks to partially substitute eucalyptus sawdust in substrates to produce the edible mushroom Pleurotus ostreatus. The substrates were formulated with proportions of 0 to 100% of eucalyptus sawdust and raw or carbonized rice husks. P. ostreatus was grown for 90 days on the substrates to evaluate mycelial growth, fresh mass production, biological efficiency, and protein and fat content. The organoleptic quality of the mushrooms produced was evaluated by sensory analysis. The substrates’ moisture, pH, and C and N contents were evaluated before and after cultivation. The substrates with 25 and 50% of raw or carbonized rice husk in a mixture with sawdust provided nitrogen and water more adequately to the fungus, improving the fresh mass production, the protein content of mushrooms, and biological efficiency (75–83%) compared to the reference substrate (100% eucalyptus sawdust), without altering the sensory quality. Given the environmental issues caused by carbonization, using raw rice husk in a mixture of up to 50% eucalyptus sawdust is recommended for P. ostreatus production.

Microbiological quality and safety of fresh mushroom products at retail level in Korea.

Several investigations and recalls have demonstrated that Listeria monocytogenes can occur on mushrooms. This study aimed to assess the microbiological quality and safety of four types of edible mushrooms (Flammulina velutipes, Pleurotus ostreatus, Pleurotus eryngii, and Agaricus bisporus) available in the Korean market, and to evaluate the prevalence of Listeria spp., including L. monocytogenes. Results revealed that out of 100 samples tested, 16% (32/200) were positive for Listeria spp. Of the Listeria-positive samples, five strains of Listeria innocua were detected. The total microbial counts ranged from 0.79 to 5.84 log CFU/g, with F. velutipes exhibiting the highest microbial load (mean 5.03 log CFU/g). These findings provide significant data for risk assessment and emphasize the need for continued monitoring of the microbiological safety of edible mushrooms.

Oyster Mushroom Spherical Virus Crosses the Species Barrier and Is Pathogenic to a New Host Pleurotus pulmonarius.

Oyster mushroom spherical virus (OMSV) is a mycovirus with a positive-sense single-stranded RNA genome that infects the edible mushroom Pleurotus ostreatus. OMSV is horizontally transferred from an infected strain to a cured strain via mycelia. The infection results in significant inhibition of mycelial growth, malformation of fruiting bodies, and yield loss in oyster mushrooms. This study successfully transferred OMSV from P. ostreatus to Pleurotus pulmonarius. However, transmission was not successful in other Pleurotus species including P. citrinopileatus, P. eryngii, P. nebrodensis, and P. salmoneostramineus. The successful OMSV infection in P. pulmonarius was further verified with Western blot analysis using a newly prepared polyclonal antiserum against the OMSV coat protein. Furthermore, OMSV infection reduced the mycelial growth rate of P. pulmonarius. The OMSV-infected strain demonstrated abnormal performance including twisted mushrooms or irregular edge of the cap as well as reduced yield of fruiting bodies in P. pulmonarius, compared to the OMSV-free strain. This study is the first report on the infection and pathogenicity of OMSV to the new host P. pulmonarius. The data from this study therefore suggest that OMSV is a potential threat to P. pulmonarius.

Mycoprotein Production by Submerged Fermentation of the Edible Mushroom Pleurotus ostreatus in a Batch Stirred Tank Bioreactor Using Agro-Industrial Hydrolysate.

The demand for cheap, healthy, and sustainable alternative protein sources has turned research interest into microbial proteins. Mycoproteins prevail due to their quite balanced amino acid profile, low carbon footprint and high sustainability potential. The goal of this research was to investigate the capability of Pleurotus ostreatus to metabolize the main sugars of agro-industrial side streams, such as aspen wood chips hydrolysate, to produce high-value protein with low cost. Our results indicate that P. ostreatus LGAM 1123 could be cultivated both in a C-6 (glucose)- and C-5(xylose)-sugar-containing medium for mycoprotein production. A mixture of glucose and xylose was found to be ideal for biomass production with high protein content and rich amino acid profile. P. ostreatus LGAM 1123 cultivation in a 4 L stirred-tank bioreactor using aspen hydrolysate was achieved with 25.0 ± 3.4 g L-1 biomass production, 1.8 ± 0.4 d-1 specific growth rate and a protein yield of 54.5 ± 0.5% (g/100 g sugars). PCA analysis of the amino acids revealed a strong correlation between the amino acid composition of the protein produced and the ratios of glucose and xylose in the culture medium. The production of high-nutrient mycoprotein by submerged fermentation of the edible fungus P. ostreatus using agro-industrial hydrolysates is a promising bioprocess in the food and feed industry.

In vitro repress of breast cancer by bio-product of edible Pleurotus ostreatus loaded with chitosan nanoparticles

Despite advances in early detection and therapy, cancer still is a significant health challenge with the highest priority for investigation. Breast cancer represents the most common cancerous disease among women in the world. The study’s purpose is to estimate the cytotoxic activity of the edible mushroom Pleurotus ostreatus extract (PE), chitosan nanoparticles (ChNPs), and PE loaded with ChNPs (PELChNPs), as well as to identify the molecular docking of the cytotoxicity of methyl gallate (MG) as a main component of the PE against breast cancer (MCF-7) cell line. High-performance liquid chromatography (HPLC) analysis of PE exhibited the existence of various phenolic and flavonoid compounds such as MG, gallic acid, chlorogenic acid, hesperetin, naringenin, rutin, and cinnamic acid. The proliferation of the MCF-7 cell line was inhibited at 1, 3.9, and 62.50 µg/mL of PELChNPs, PE, and ChNPs, respectively. PELChNPs were more effective against the MCF-7 cell line than PE, particularly at low concentrations. For instance, at 7.8 µg/mL of PELChNPs and PE, the inhibitory % of MCF-7 proliferation was 20.59±1.75% and 8.57±0.59%, respectively. At 15.6 µg/mL of PELChNPs and PE, the inhibitory % of MCF-7 proliferation was 51.37±1.09% and 25.18±1.64%, respectively. While there is slight difference in the inhibition % of MCF-7 cells (98.64±0.21 and 97.22±0.16%) at high concentration 500 µg/mL of PELChNPs and PE, respectively. IC50 was 15.25 ± 0.54 µg/mL, 46.27 ± 1.94 µg/mL, and 337.38 ± 13.68 µg/mL against MCF-7 cell line of PELChNPs, PE, and ChNPs, respectively. The value of IC50 documented the efficacy of PELChNPs compared with the IC50 (5.91 ± 0.43 µg/mL) of Vinblastine sulfate. Noticeable distortions were observed in the MCF-7 cell line mainly treated with PELChNPs, followed by PE alone. While ChNPs exhibited less effect on the morphology of the MCF-7 cell line. Antioxidant activity of ChNPs, PE, and PELChNPs was evaluated compared with Trolox, which reflected IC50 = 118.33 ± 4.02, 85.63 ± 3.96, 36.80 ± 2.52 and 24.74 ± 0.45 µg/mL. Methyl gallate binding interactions were assessed using molecular docking with the MOE-Dock tool against the target crystal structures of Breast cancer cell line 3HB5. The results shed light on how molecular modeling techniques can inhibit methyl gallate with possible uses in treating breast cancer.

Structure Analysis of the <i>MatA</i> Locus of Sexual Compatibility in the Edible Mushroom <i>Pleurotus ostreatus</i>

The edible oyster mushroom Pleurotus ostreatus is one of the most cultivated species worldwide. Morphogenesis associated with the fruit bodies maturation is controlled by two unlinked loci of sexual compatibility matA and matB with multiple alleles (tetrapolar system of sexual compatibility). Quantitative analysis of the alleles of mating compatibility loci in 17 natural isolates collected in the Moscow region was performed in mon-mon (monokaryon – monokaryon) and di-mon (dikaryon – monokaryon) crossings. Four monokaryotic testers strains which were heteroallelic at both mating type loci were obtained for each of the five natural mushroom isolates by using original technique of sterile spore prints on Petri dishes and mon-mon crossing. Twelve natural isolates were crossed via di-mon mating with the four monokaryotic testers M-38. Genetic analysis of the alleles of sexual compatibility loci in 17 natural isolates revealed multiple alleles at both loci: at least 10 alleles at matA locus and eight alleles at matB locus. Structural organization analysis of the matA locus was performed in silico for homokaryotic strains PC9 and PC15 based on the genome sequencing data available at DOE Joint Genome Institute. The matA locus is proved to be of extremely divergent structure: there are one copy of the homeodomain gene hd1 and one copy of the hd2 gene in the PC9 strain, whereas the matA locus of the PC15 strain is composed by two copies of hd1.1 and hd1.2 genes (class HD1 homeodomain proteins) and one copy of hd2 gene (class HD2 proteins). Comprehensive analysis of amino acid sequences of HD1 and HD2 homeodomain proteins demonstrated that the proteins have a globular structure with the nuclear localization and contain a variable N-terminus and the more conservative DNA-binding domain with a specific conservative motif WFXNXR in the third ɑ-helix. The results approve the opinion that multiple alleles of the matA locus of sexual compatibility in basidiomycete fungi is achieved by different copies’ number of the coding hd genes within the locus, as well as by the variability of the coding gene sequences.

Edible and medicinal mushrooms (Pleurotus ostreatus, Ustilago maydis, Ganoderma lucidum) reduce endoplasmic reticulum stress and inflammation in adipose tissue of obese Wistar rats fed with a high fat plus saccharose diet.

Obesity is an increasing global public health problem. A strategy to treat obesity is the use of functional foods. Edible and medicinal mushrooms contain diverse bioactive compounds showing important antihyperlipidemic, antioxidant, and prebiotic properties. We analysed the effects of adding (10%) of Pleurotus ostreatus (Po, basidiomata), Ganoderma lucidum (Gl, basidiomata), or Ustilago maydis (Um, galls), milled, to a high fat plus saccharose diet (HFD + S) for 6 months in a model of obesity with Wistar rats. We assessed weight gain, body composition, lipid parameters, endoplasmic reticulum stress (proteins and inflammatory markers: BiP, XBP-1, JNK, p-JNK, TNF-α), and adiponectin in subcutaneous adipose tissue (SAT). The consumption of edible and medicinal mushrooms decreased weight gain (-17.2-30.1%) and fat mass (-23.7-43.1%), maintained fat-free mass, reduced levels of serum biochemical parameters (TC: -40.1-44.1%, TG: -37.7-51.6%, LDL-C: -64.5-71.1%), and prevented adipocyte hypertrophy (-30.9-36.9%) and collagen deposition (-70.9-73.7%) in SAT. Compared with the HFD + S group, mushroom consumption by Wistar rats significantly reduced the expression of proteins associated with endoplasmic reticulum stress and inflammation (BiP: -72.2-88.2%; XBP-1: -71.5-81.8%; JNK: -71.2-90.0%; p-JNK: -37.3-81.0%; TNF-α: -80.7-91.5%), whereas significantly increased adiponectin protein expression (246.4-654.2%) in SAT. These effects outperformed those obtained through the commercial lipid-lowering drug atorvastatin, contributing synergistically to prevent further obesity-related dysfunctions, such as insulin resistance derived from inflammation and ER stress in adipose tissue. Bioactive compounds from edible, functional and medicinal mushrooms represent new emerging therapies for obesity treatments using natural products.

Phenolic Content, Antibacterial and Antioxidant Potential of Several Edible Agaricomycetes Mushrooms Sold in Public Bazaar in Bolu, Turkey

Edible mushrooms are important natural foods that have been used since ancient times due to their delicious taste, high nutritional value, and various biological activities. In this study, antibacterial (against 10 different human pathogens) and antioxidant potentials (free radical scavenging activity and total phenol-flavonoid content) of 13 different wild-growing and the most popular edible mushrooms (Lactarius salmonicolor, L. deliciosus, L. volemus, L. piperatus, Boletus edulis, Marasmius oreades, Agaricus campestris, Tricholoma terreum, Hydnum repandum, Coprinus comatus, Ramaria sp., Cantharellus cibarius, and Pleurotus ostreatus) sold in a public bazaar in Bolu-Turkey were evaluated. Strong antibacterial capacities were observed with all tested Lactarius species, as well as M. oreades, A. campestris, T. terreum, H. repandum, and Ramaria sp. Significant antibacterial potentials of T. terreum and C. comatus against Staphylococcus epidermidis, Serratia marcescens, and Proteus vulgaris were observed for the first time. H. repandum strongly inhibited all tested Gram-positive bacteria (Staphylococcus aureus, S. epidermidis, and Streptococcus pyogenes). It was remarkable to reveal strong growth inhibition of M. oreades against S. aureus (29.33 ± 1.11 mm) for the first time. The highest total phenolic content was revealed with L. delicious (193.42 ± 0.77 mg GAE/g dw and 198 ± 0.79 mg TAE/g dw), while L. salmonicolor had the highest total flavonoid content (358.33 ± 15.27 mg CE/g dw). B. edulis demonstrated the strongest antioxidant activity with the lowest IC50 value (4.48 ± 0.04 μg/mL). Moreover, L. deliciosus and M. oreades also had high antioxidant potential with the lowest IC50 values (4.76 ± 0.01 μg/mL and 4.77 ± 0.02 μg/mL, respectively). Total phenolic contents of tested mushrooms were highly correlated with their antioxidant capacities. L. delicious is the most well-known and the most delicious mushroom sold in Bolu's public bazaar. The obtained results for this mushroom were notable in terms of the greatest total phenol-flavonoid content and strong antioxidant capability. The antioxidant capacity and polyphenol content of L. deliciosus, M. oreades, H. repandum, A. campestris, and B. edulis, as well as their antibacterial activity, were quite outstanding, and our findings demonstrated the importance of these mushrooms as nutraceutical products.

In vitro evaluation of methanol extracts of edible fungi Pleurotus ostreatus and Lentinula edodes against Rhyssomatus nigerrimus Fahraeus.

The study aimed to evaluate the insecticidal activity of extracts of edible mushrooms Pleurotus ostreatus and Lentinula edodes against Rhyssomatus nigerrimus. Methanol:water extracts (70:30) of P. ostreatus and L. edodes were made and evaluated in two in vitro tests (exposure and immersion toxic effect) against R. nigerrimus. Subsequently, the toxicity test of the extracts against Artemia salina was evaluated. These extracts were subjected to colorimetric tests and gas chromatography-mass spectrometry. The results showed a mortality effect against R. nigerrimus of 50% for the P. ostreatus 2 extracts at a concentration of 20% in the immersion test. Likewise, in the toxic effect test, 90% mortality was observed after five days of exposure to a concentration of 10%. On the other hand, for the toxicity test, the extract that showed the values with the highest mortality against A. salina was P. ostreatus, starting with 80% mortality at 100μg/mL. The functional groups present in the extracts were saponins, coumarins, and alkaloids. Furthermore, the presence of more than 7 compounds in the mushroom extracts evaluated is reported. This study demonstrates the insecticidal activity of P. ostreatus and L. edodes fungal extracts and indicates the importance of using different in vitro tests to elucidate the mechanism of action for future studies.

Functional Characterization of Laccase Isozyme (PoLcc1) from the Edible Mushroom Pleurotus ostreatus Involved in Lignin Degradation in Cotton Straw.

Fungal laccases play important roles in the degradation of lignocellulose. In this study, the laccase producing cotton straw medium for Pleurotus ostreatus was optimized by single-factor and orthogonal experiments, and to investigate the role of Lacc1 gene, one of the laccase-encoding genes, in the degradation of cotton straw lignin, an overexpression strain of Lacc1 gene was constructed, which was analyzed for the characteristics of lignin degradation. The results demonstrated that the culture conditions with the highest lignin degradation efficiency of the P. ostreatus were the cotton straw particle size of 0.75 mm, a solid-liquid ratio of 1:3 and containing 0.25 g/L of Tween in the medium, as well as an incubation temperature of 26 °C. Two overexpression strains (OE L1-1 and OE L1-4) of Lacc1 gene were obtained, and the gene expression increased 12.08- and 33.04-fold, respectively. The results of 1H-NMR and FTIR analyses of significant changes in lignin structure revealed that Lacc1 gene accelerated the degradation of lignin G-units and involved in the cleavage of β-O-4 linkages and the demethylation of lignin units. These findings will help to improve the efficiency of biodelignification and expand our understanding of its mechanism.

Structural and Functional Analysis of Peptides Derived from KEX2-Processed Repeat Proteins in Agaricomycetes Using Reverse Genetics and Peptidomics.

Bioactivities of fungal peptides are of interest for basic research and therapeutic drug development. Some of these peptides are derived from "KEX2-processed repeat proteins" (KEPs), a recently defined class of precursor proteins that contain multiple peptide cores flanked by KEX2 protease cleavage sites. Genome mining has revealed that KEPs are widespread in the fungal kingdom. Their functions are largely unknown. Here, we present the first in-depth structural and functional analysis of KEPs in a basidiomycete. We bioinformatically identified KEP-encoding genes in the genome of the model agaricomycete Coprinopsis cinerea and established a detection protocol for the derived peptides by overexpressing the C. cinerea KEPs in the yeast Pichia pastoris. Using this protocol, which includes peptide extraction and mass spectrometry with data analysis using the search engine Mascot, we confirmed the presence of several KEP-derived peptides in C. cinerea, as well as in the edible mushrooms Lentinula edodes, Pleurotus ostreatus, and Pleurotus eryngii. While CRISPR-mediated knockout of C. cinerea kep genes did not result in any detectable phenotype, knockout of kex genes caused defects in mycelial growth and fruiting body formation. These results suggest that KEP-derived peptides may play a role in the interaction of C. cinerea with the biotic environment and that the KEP-processing KEX proteases target a variety of substrates in agaricomycetes, including some important for mycelial growth and differentiation. IMPORTANCE Two recent bioinformatics studies have demonstrated that KEX2-processed repeat proteins are widespread in the fungal kingdom. However, despite the prevalence of KEPs in fungal genomes, only few KEP-derived peptides have been detected and studied so far. Here, we present a protocol for the extraction and structural characterization of KEP-derived peptides from fungal culture supernatants and tissues. The protocol was successfully used to detect several linear and minimally modified KEP-derived peptides in the agaricomycetes C. cinerea, L. edodes, P. ostreatus, and P. eryngii. Our study establishes a new protocol for the targeted search of KEP-derived peptides in fungi, which will hopefully lead to the discovery of more of these interesting fungal peptides and allow a further characterization of KEPs.

Fortification of soy milk with prebiotic natural ß-glucan derived from edible mushrooms Pleurotus ostreatus and Agaricus bisporus

Comparative analysis of two catalytically distinct endoglucanases from Aspergillus nidulansBaljit Kaur, H.S. Oberoi, B.S. Chadha

Risk Assessment of Heavy Metals Occurrence in Two Wild Edible Oyster Mushrooms (Pleurotus spp.) Collected from Rajaji National Park.

This study aimed at assessing the concentration of six heavy metals (Cd, Cr, Cu, Fe, Mn, and Zn) in two wild edible oyster mushrooms (Pleurotus ostreatus and Pleurotus djamor) collected from Rajaji National Park in Haridwar, India. For this purpose, mushroom samples were collected from selected locations (forest, residential, tourist, industrial areas, and transportation activities) from June 2021 to July 2022 and subsequently analyzed for selected heavy metals using atomic absorption spectroscopy (AAS). Results showed that both Pleurotus spp. had significantly varying (p < 0.05) concentrations of heavy metals. However, P. ostreatus showed relatively higher concentration levels of these metals compared to P. djamor. The mean concentrations (mg/kg dry weight) of the Cd, Cr, Cu, Fe, Mn, and Zn in P. ostreatus and P. djamor were 0.10 and 0.08, 0.87 and 0.64, 16.19 and 14.77, 28.49 and 27.15, 9.93 and 8.73, and 18.15 and 15.76, respectively. As indicated by the multivariate analysis tools i.e., principal component analysis (PCA) and hierarchical cluster analysis (HCA), the locations near the residential, industrial, and transportation activities had higher concentration levels of heavy metals. Moreover, the health risk studies using the target hazard quotient (THQ < 1) showed no significant health risk as the consumption of both Pleurotus spp., except for at one location, had high-traffic activities. The findings of this study provide vital information about the occurrence of potentially toxic heavy metals in wild edible Pleurotus spp. in Rajaji National Park in Haridwar, India representing a safeguard for mushroom consumers.

Bio-directed Chemical Study of Pleurotus ostreatus Spent Substrate and Its Nematicidal Activity.

In the present study, the nematicidal activity of the chemical fractionation of the spent substrate of the edible mushroom Pleurotus ostreatus against eggs and L3 larvae of Haemonchus contortus was evaluated. The hydroalcoholic extract of the spent substrate was subjected to a bipartition with ethyl acetate giving two fractions: one aqueous (F. Ac) and one organic (F. AcOET). Both fractions were evaluated against eggs and L3 larvae at different concentrations (5, 2.5, 1.25, 0.625 and 0.3125mg/mL) and 2% methanol, PBS and thiabendazole (5mg/mL) as controls. Chemical fractionation of F. AcOET was performed in open column chromatography where 76 fractions were obtained and when analyzed by thin layer chromatography (TLC) were grouped into 11 mixtures (R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11). These mixtures were evaluated at 10mg/mL against eggs and L3 larvae. The data obtained were analyzed by ANOVA and a Tukey test in the SAS V9 program. The results showed that, in the evaluation of F. AcOET and F. Ac, for the inhibition of egg hatching, the highest percentages were 78.80 and 76.89% at 5mg/mL, respectively. As for the percentage of larval mortality, F. AcOET obtained 60.91 and F. Ac 29.77% at 5mg/mL. The results of the evaluations of the mixtures showed that mixtures R4, R5 obtained 100 and 95.41% larval mortality and mixtures R6 and R7 presented 100% inhibitory activity of egg hatching, so these were analyzed by gas chromatography mass spectrometry finding compounds such as vanillin, β-sitosterol, ρ-methyl ρ-hydroxycinnamate and ρ-hydroxybenzaldehyde. The results of the present study demonstrate that the spent substrate of P. ostreatus has potential anthelmintic activity against H. contortus. Moreover, by reusing and taking advantage of this substrate, its environmental pollution effects can be reduced.

In silico identification of potential inhibitors of MPS1 from edible mushroom (Pleurotus ostreatus) to prevent aneuploidy and tumorigenesis

In silico identification of potential inhibitors of MPS1 from edible mushroom (Pleurotus ostreatus) to prevent aneuploidy and tumorigenesis

Detection of autophagy-related structures in fruiting bodies of edible mushroom, Pleurotus ostreatus.

Autophagy is involved in various fungal morphogenetic processes. However, there are limited reports regarding the role of autophagy in mushroom fruiting body formation. The purpose of this study was to reveal the autophagy-related structures in mushroom-forming fungi. The edible mushroom Pleurotus ostreatus was used in this study. Transmission electron microscopy revealed double-membrane bounded structures containing cytoplasmic components in the fruiting bodies of this fungus. Some of these double-membrane structures were observed to interact with the vacuoles. Additionally, curved flat cisternae of various lengths were detected in the cytoplasm. The shape, size and thickness of the limiting membrane of the double-membrane structures and the flat cisternae corresponded well with those of the autophagosomes and the isolation membranes, respectively. Regarding autophagosome formation, a membrane-bound specific zone was detected near the isolation membrane, which appeared to expand along the novel membrane. This is the first detailed report showing autophagy-related structures in P. ostreatus and provides a possible model for autophagosome formation in these filamentous fungi.

Preliminary Studies on the Effects of Oyster Mushroom Spherical Virus China Strain on the Mycelial Growth and Fruiting Body Yield of the Edible Mushroom Pleurotus ostreatus.

Simple SummaryOyster mushroom spherical virus (OMSV) is a positive-sense single-stranded RNA mycovirus which is associated with a devastating oyster mushroom die-back disease. However, little is known about its classification, and the effects of OMSV infection on its fungal host remain unclear. In the present study, we present the molecular evidence that virus isolates from the P. ostreatus 8129 strain in China represent a new strain of OMSV, named OMSV-Ch. Phylogenetic analysis based on the putative replication protein (RP) suggest that the OMSV may belong to a new yet-to-be-established genus of the Tymoviridae. Using single hyphal tip cultures combined with high-temperature treatment, we obtained the OMSV-Ch-cured P. ostreatus strain. Preliminary studies indicate that OMSV-Ch infection can significantly inhibit mycelial growth, cause malformation symptoms, and reduce the yield of the fruiting bodies of the edible mushroom P. ostreatus. Furthermore, OMSV-Ch can horizontally transfer to a virus-cured strain.Oyster mushroom spherical virus (OMSV) is a positive-sense single-stranded RNA mycovirus which is associated with a devastating oyster mushroom die-back disease. However, little is known about its diversity, and the effects of OMSV infection on its fungal host are not well understood. In this study, we determined the nearly complete nucleotide sequence of OMSV isolated from cultivated oyster mushrooms in China. Sequence analysis suggested that the virus represents a new strain of OMSV (referred to here as OMSV-Ch). A GenBank BLAST search of the genomic sequences demonstrated that the OMSV-Ch had the highest identity (74.9%) with the OMSV from Korea (OMSV-Kr). At the amino acid–sequence level, these two strains shared 84.1% identity in putative replication protein (RP) and 94.1% identity in coat protein (CP). Phylogenetic analysis based on RP showed that OMSV-Ch clustered with OMSV-Kr, closely related to Tymoviridae. Phylogenetic analysis based on both the RP and CP showed that OMSV had a distant clade relationship with tymoviruses, marafiviruses, and maculaviruses. We obtained the OMSV-Ch-free Pleurotus ostreatus strain via single hyphal tip cultures combined with high-temperature treatment. Preliminary studies indicate that OMSV-Ch can significantly inhibit mycelial growth, cause malformations of the fruiting bodies, and reduce the yield of P. ostreatus. Co-cultivation resulted in horizontal transmission of the OMSV-Ch to a virus-cured strain. The findings of our study contribute to the prevention and control of mycoviral diseases in the future.

Dietary cerebrosides in seven edible mushrooms: One step detection, quantification, and Si-SPE assisted isolation

Cerebrosides are important high-value dietary molecules with unique biological functions which are found extensively in mushrooms. However, tedious detection/extraction methods and lack of adequate reports led mushrooms to be an under-utilized cerebroside source. In this study, two of glycosphingolipids, cerebrosides B and E were identified and further confirmed from seven edible mushrooms (Pleurotus eryngii, Agaricus bisporus, Hypsizygus marmoreus, Pleurotus ostreatus, Agrocybe aegerita, Flammulina velutipes and Lentinus edodes) by high-resolution tandem mass spectrometry and hydrogen-1/carbon-13 nuclear magnetic resonance. A rapid method using high-performance liquid chromatography coupled with an evaporative light-scattering detector (HPLC-ELSD) was explicitly developed to detect and isolate cerebrosides from edible fungal matrices. The developed method accurately quantified cerebrosides B (0.15–1.05 mg/g, dry matter) and E (0.18–1.80 mg/g, dry matter), thus verified its applicability. Furthermore, silica solid-phase extraction was established to obtain cerebroside-rich extracts from shiitake mushroom (>46 %, peak area %) and was later advanced to semi-preparative HPLC, which led to the isolation of cerebroside molecules (>98 % purity, peak area %). The current work presents a one-step, cost-effective, sensitive HPLC-ELSD method that accurately quantified cerebrosides from edible mushrooms and can be easily adapted for other fungal species.

Growth and proximate composition of Pleurotus ostreatus cultivated on green bocaiuva pulp substrates with different nitrogen sources

The aim of this work was to evaluate the growth and the proximate composition of the mycelium-based bocaiuva pulp with the edible mushroom Pleurotus ostreatus on green bocaiuva flour added with different sources of nitrogen (urea, ammonium nitrate and sulfate ammonia). Growth was monitored by kinectics. At the end, the proximate composition of the best three treatments (dehydrated green bocaiuva pulp and water, T1; dehydrated green bocaiuva pulp and ammonium nitrate, T3; and green bocaiuva pulp/wheat bran and ammonium nitrate, T7) was determined. Ammonium nitrate was the nitrogen source that showed the greatest growth in both substrates (T3:8.33 cm and T7:7.67 cm) in relation to the other treatments (4.67 to 7.17 cm), with emphasis on the green bocaiuva pulp. The substrate with green bocaiuva pulp and water was the one that showed the highest growth (7.50 cm), which was close to the treatment with mixed substrate and ammonium nitrate (7.67 cm). The treatment with the green bocaiuva pulp and ammonium nitrate (T3) was highlighted due to its significant increase in proteins (9.42 g 100 g-1) and fibers (5.21 g 100 g-1), and decrease in carbohydrates (9.52 g 100 g-1), in comparison to the other treatments T7 (8.94, 2.16, and 5.99 g 100 g-1, respectively) and T1 (2.78, 4.33, and 2.28 g 100 g-1, respectively). The product obtained from the growth of P. ostreatus in green bocaiuva pulp presents promising perspectives to be utilized as raw material for the development of new food products with added nutritional value.