Study on chemical constituents of an edible mushroom Volvariella volvacea and their antitumor activity in vitro.

Phytochemical investigation of the fruiting body of Volvariella volvacea led to the isolation of a new furanone, 2(5H)-furanone-4-propionic acid named volvafuranone A (1), together with twelve known compounds (2-13). Compounds 2-7, 9-11 were isolated from this mushroom for the first time. The isolated compounds were assessed for their cytotoxicity against four human tumour lines (SGC-7901, PC-3M, MCF-7, HepG-2), and the results showed that compound 2, 3, 12, 13 have significant cytotoxicity with IC50 values of 5.90 µM (HepG-2), 20.72 µM (HepG-2), 27.98 µM (PC-3M) and 23.15 µM (PC-3M), respectively.

Identification of dihydro-ß-ionone as a key aroma compound in addition to C8 ketones and alcohols in Volvariella volvacea mushroom.

The volatile compounds of Volvariella volvacea mushroom were investigated by solvent assisted flavor evaporation (SAFE)/gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), odor activity value (OAV), combined with aroma reconstitution and omission. The results showed that a total of 63 compounds were detected after SAFE extraction. A total of 26 compounds were determined after GC-O and 17 compounds whose OAV greater than 1 were subjected to reconstitution and omission experiments. The results showed that dihydro-ß-ionone, 1-octen-3-one, 1-octen-3-ol, γ-undecalactone, 3-octanol, 2-octanone, hexanal, 2-methylbutanal, camphene, carvone, 2-nonanone, and phenylacetaldehyde have been successfully identified as the key aroma compounds. More significantly, dihydro-ß-ionone as a key aroma compound was first found in Volvariella volvacea mushroom.

Identification of umami-tasting peptides from Volvariella volvacea using ultra performance liquid chromatography quadrupole time-of-flight mass spectrometry and sensory-guided separation techniques.

Mushroom peptides produced by high-pressure cooking from Volvariella volvacea were found to retain and enhance the umami taste. Three tasty peptides were identified as Ala-Ser-Asn-Met-Ser-Asp-Leu (ASNMSDL), Tyr-Tyr-Gly-Ser-Asn-Ser-Ala (YYGSNSA) and Leu-Gln-Pro-Leu-Asn-Ala-His (LQPLNAH) by UPLC-Q-TOF-MS, after a series of separation methods of ultrafiltration, gel filtration chromatography and reverse phase high-performance liquid chromatography. Each fractionation step is based on the results of sensory evaluation. ASNMSDL and LQPLNAH have umami taste with threshold values of 10.19 and 12.63 mmol/L, respectively. In addition, these two peptides also showed umami-enhancing properties with a threshold estimated at 13.58 and 18.95 mmol/L, respectively. Furthermore, the peptides showed better sensory taste than mixtures of their constituent amino acids. After separation and purification, the content of taste peptides in Volvariella volvacea is about 1.4%.

Phenolics, tocopherols and fatty acid profiling of wild and commercial mushrooms from Pakistan.

Mushrooms can be used as nutraceutical or functional foods to maintain and promote good health. In the present study, wild Ganoderma lucidum and four commercial mushrooms, Pleurotus ostreatus, Volvariella volvacea, Hericium erinaceus and Lentinus edodes, collected from Pakistan were screened for phenolics, tocopherols and fatty acid contents. High performance liquid chromatography analysis of phenolic acids showed that chlorogenic acid, ferulic acid, gallic acid, p-Coumaric and caffeic acids were observed in selected mushrooms. H. erinaceus contained high amounts of chlorogenic acid (11.49±0.1 µ/g of dry weight) and ferulic acid (7.84±0.7 µg/g of dry weight). γ-tocopherol and lutein were present in all studied mushrooms. Lutein contents were higher in H. erinaceus (2.42±0.087 µg/g of DW) followed by V. volvacea> P. ostreatus> L. edodes. γ-tocopherol was observed in the range of 74.25±3.01 to 29.65±1.2 µg/g of dry weight. GC/MS analysis of fatty acids showed that linoleic acid (18’:2n6c), oleic acid (18’:1n9c), palmitic acid (C16:0), stearic acid (C18:0), linolenic acid (18’:3n3) and nonadecanoic acid (C19-0), were the main fatty acids found in selected mushrooms. The unsaturated fatty acids were predominated over saturated fatty acids. It is concluded that selected mushrooms are good sources of antioxidant compounds and unsaturated fatty acids.

Ultrasound-Assisted Extraction of Polysaccharides from Volvariella volvacea: Process Optimization and Structural Characterization.

The aims of the present study were to optimize the operational parameters to maximize the yield of ultrasound-assisted polysaccharide extraction from Volvariella volvacea (straw mushroom) fruiting bodies by using for the first time one-factor-at-a-time and three-level Box-Behnken factorial designs. A maximum polysaccharide yield of 8.28 ± 0.23% was obtained under the optimized conditions of ultrasound power of 175 W, extraction temperature of 57 °C, extraction time of 33 min, and the ratio of liquid to raw material of 25:1, respectively. Compared to the hot-water extraction, the ultrasound-assistance favored the extraction of polysaccharides from V. volvacea for its higher polysaccharide yield and efficiency. Further preliminary polysaccharide structural characterization indicated that ultrasound treatment affected the monosaccharide compositions and ratios, and molecular weight range of polysaccharides extracted from V. volvacea.

N- and C-terminal truncations of a GH10 xylanase significantly increase its activity and thermostability but decrease its SDS resistance.

XynII from Volvariella volvacea has high sodium dodecyl sulfate (SDS) resistance, with the potential for industrial applications under harsh conditions. It consists of a single glycoside hydrolase family 10 (GH10) catalytic domain but contains an additional unique 10 and 4 amino acid residues at the N- and C-terminus, respectively. In this study, five XynII derivatives with N- and/or C-terminus deletions were constructed to determine the effects of these regions on enzyme activity, substrate specificity, thermostability, and SDS resistance. Our results revealed that N- and/or C-terminal truncations significantly increased enzyme activity and thermostability, but reduced SDS resistance. Specifically, the XynIIΔNC4 mutant had 2.53-fold more catalytic efficiency (k cat/K m) towards beechwood xylan than wild-type and 3.0-fold more thermostability (t 1/2 [55°C]). XynIIΔNC4 displayed 3.33-, 4.38-, 1.37-, and 1.98-fold more activity against xylotriose, xylotetraose, xylopentaose, and xylohexaose, respectively, than XynII did. However, its half-life (t 1/2) in 4 % SDS was only 1.72 h, while that of XynII was 4.65 h. Circular dichroism analysis revealed that deletion of N- and C-terminal segments caused minor changes in secondary structure. Our observations suggest that the extra N- and C-terminal segments in wild-type XynII evolved to strengthen the interaction between these regions of the protein, making the local structure more rigid and reducing structural flexibility. In this way, N- and C-terminal truncations increased the thermostability and activity of XynII on different xylans and linear xylooligosaccharides, but reduced its resistance to SDS.

Screening of biological, morphological, and molecular characteristics of single-spore isolate collections of the straw mushroom, Volvariella volvacea (higher Basidiomycetes) from India.

Of the 2 parent strains and 6 single-spore isolates (SSIs) used in this study, the SSIs BBSR-007 and BBSR-002 of the culinary-medicinal straw mushroom Volvariella volvacea exhibited superior growth characteristics on different growth media. These also took less time until first harvest (days after spawning), gave higher numbers of fruiting bodies per unit weight of substrate, and provided a higher mushroom yield on composted substrate. The fruiting body weight of isolate BBSR-007 was significantly higher compared to BBSR-002. On pasteurized paddy straw, the SSI BBSR-007 had a higher mushroom yield than BBSR-002. The contents of dry matter, protein, and other elements (sodium, potassium, and calcium) were on par in both the parent strains and different SSIs, except SSI OE-55-08, which had highest dry matter, protein content, and potassium/-to-odium ratio. In amplified ribosomal DNA restriction analysis, the SSIs did not show any distinctness, whereas in amplified fragment length polymorphism, the SSI OE-55-08 of parent strain OE-55 formed a separate clade; of 4 SSIs of strain OE-274, the SSI BBSR-003 formed a separate clade than other SSIs. The genetically distinct SSI OE-55-08 produced the highest numbers of fruit bodies per unit weight of substrate and exhibited the highest amounts of dry matter and protein in its fruit bodies. Another slightly distinct SSI, BBSR-003, formed white aerial mycelia on growth substrate, and its fruit bodies exhibited the highest levels of sodium and calcium.

Extracellular expression and efficient purification of a functional recombinant Volvariella volvacea immunomodulatory protein (FIP-vvo) using Pichia pastoris system.

The fungal immunomodulatory proteins (FIPs) are a new protein family identified from several edible and medical mushrooms and play an important role in antitumor, anti-allergy and immunomodulating activities. A gene encoding the FIP-vvo was cloned from the mycelia of Volvariella volvacea and recombinant expressed in the Pichia pastoris expression system. SDS-PAGE, amino acid composition and circular dichroism analyses of the recombinant FIP-vvo (reFIP-vvo) indicated that the gene was correctly and successfully expressed. In vitro assays of biological activities revealed that the reFIP-vvo exhibited similar immunomodulating capacities as native form. The reFIP-vvo significantly stimulated the proliferation of mouse spleen lymphocytes and apparently enhanced the expression level of IFN-γ released from the mouse splenocytes. Taken together, the FIP-vvo gene from V. volvacea has been integrated into the yeast genome and expressed effectively at a high level (about 410mg/L), it was capable of agglutinating sheep and rat red blood cells. The reFIP-vvo possessed very similar biological activities to native FIPs, suggesting its potential application as a food supplement or immunomodulating agent in pharmaceuticals and even medical studies.

[Sequence characterization and differential expression of a glutathione S-transferase gene vv-gto1 from Volvariella volvacea].

OBJECTIVE: Based on the analysis of omics data of Volvariella volvacea, a gene encoding glutathione S- transferase (GSTs) named vv-gtol was obtained. To reveal the role of GSTs in the growth and development in edible fungi, the structure, the sequence characters and the expression profile of a GST gene vv-gto1 of Volvariella volvacea were analyzed. METHODS: ZOOM software was used to map sequencing read (reads) from genome and transcriptome against the splicing sequence of genome, to confirm the complete length and the accuracy of the gene sequence, and to visualize gene structure. The MEGA 5.1 was used to do the multiple sequence alignment and phylogenetic tree analysis. Real time fluorescent quantitative PCR was used to determine the expression levels of vv-gtol at different growth periods of Volvariella volvacea. RESULTS: The full sequence of vv-gtol covered 2083 bp, containing 11 exons and 10 introns, and encoded a protein with 356 amino acids. 5'UTR was 305 bp which contains one intron region, and 3'UTR was 86bp. Two intron retentions could be recognized during RNA processing, and the transcripts formed by the intron retention could not translate the correct conservative functional domains. The full-length of vv-gtol had more than 50 accurate positioning genome sequencing reads, suggesting that genome sequencing and assembly results are accurate and reliable. The phylogenetic tree showed that GTO1 of Volvariella volvacea belonged to the subclass I of the Omega class of glutathione S-transferase superfamily, and had the closest relationship with GTO1 and GTO2 in Phanerochaete chrysosporium. The analysis of digital gene expression profiling, fluorescence quantitative PCR and proteomics showed that vv-gtol had the highest expression level in the heterokaryotic hyphae. CONCLUSIONS: This is the first time to obtain a gene encoding glutathione S-transferase from Volvariella volvacea which belongs to Omega class. Our study showed that the gene may play an important role during the special biological functions of heterokaryotic hyphae. This study also suggested that Volvariella volvacea heterokaryotic hyphae in H1521 had stronger resistance ability than other samples. In addition, vv-gto1 could form different alternative splicesome to regulate gene transcription and translation, and ultimately affect the function of the protein.

A novel neutral xylanase with high SDS resistance from Volvariella volvacea: characterization and its synergistic hydrolysis of wheat bran with acetyl xylan esterase.

A neutral xylanase (XynII) from Volvariella volvacea was identified and characterized. Unlike other modular xylanases, it consists of only a single GH10 catalytic domain with a unique C-terminal sequence (W-R-W-F) and a phenylalanine and proline-rich motif (T-P-F-P-P-F) at N-terminus, indicating that it is a novel GH10 xylanase. XynII exhibited optimal activity at pH 7 and 60 °C and stability over a broad range of pH 4.0-10.0. XynII displayed extreme highly SDS resistance retaining 101.98, 92.99, and 69.84 % activity at the presence of 300 mM SDS on birchwood, soluble oat spelt, and beechwood xylan, respectively. It remained largely intact after 24 h of incubation with proteinase K at a protease to protein ratio of 1:50 at 37 °C. The kinetic constants K(m) value towards beechwood xylan was 0.548 mg ml⁻¹, and the k(cat)/K(m) ratio, reflecting the catalytic efficiency of the enzyme, was 126.42 ml mg⁻¹ s⁻¹ at 60 °C. XynII was a true endo-acting xylanase lacking cellulase activity. It has weak activity towards xylotriose but efficiently hydrolyzed xylans and xylooligosaccharides larger than xylotriose mainly to xylobiose. Synergistic action with acetyl xylan esterase (AXEI) from V. volvacea was observed for de-starched wheat bran. The highest degree of synergy (DS 1.42) was obtained in sequential reactions with AXEI digestion preceding XynII. The high SDS resistance and intrinsic stability suggested XynII may have potential applications in various industrial processes especially for the detergent and textile industries and animal feed industries.

Lead accumulation in the straw mushroom, Volvariella volvacea, from lead contaminated rice straw and stubble.

Straw mushrooms were grown on lead contaminated rice straw and stubble. Study materials were dried, acid digested, and analyzed for lead using flame atomic absorption spectrophotometry. The results showed the highest lead concentration in substrate was 445.350 mg kg⁻¹ in Treatment 3 (T3) and the lowest was BD (below detection) in Treatment 1 (T1). The maximum lead content in straw mushrooms was 5.072 mg kg⁻¹ dw in pileus of T3 and the minimum lead content in straw mushrooms was BD in egg and mature (stalk and pileus) stage of T1. The lead concentration in straw mushrooms was affected by the age of the mycelium and the morphology of mushrooms. Mushrooms' lead uptake produced the highest accumulation in the cell wall. Some lead concentrations in straw mushrooms exceeded the EU standard (>3 mg kg⁻¹ dw).

A ß-glucan from the alkaline extract of a somatic hybrid (PfloVv5FB) of Pleurotus florida and Volvariella volvacea: structural characterization and study of immunoactivation.

A water soluble polysaccharide isolated from the alkaline extract of the somatic hybrid mushroom (PfloVv5FB), obtained through protoplast fusion between Pleurotus florida and Volvariella volvacea strains was found to contain d-glucose only. Structural investigation was carried out using acid hydrolysis, methylation analysis; periodate oxidation, and NMR studies ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HSQC, and HMBC). On the basis of the above mentioned experiments the structure of the repeating unit of the polysaccharide was established as: This polysaccharide exhibited strong immunoactivation of macrophages, splenocytes as well as thymocytes.

Sequence and comparative analysis of the MIP gene in Chinese straw mushroom, Volvariella volvacea.

The mitochondrial intermediate peptidase (MIP) gene is conserved in fungi. It is linked closely with the mating-type A (mtA) gene. In this study, a fragment of the MIP gene in Volvariella volvacea (Bull. ex Fr.) Singer was first cloned by homologue-based cloning technology. Subsequently, the entire MIP DNA sequence (PYd21-MIP) was obtained after the fragment was compared with the genomic data through BLAST analysis. The PYd21-MIP sequence appeared to be homologous with the MIP gene in other fungi. Phylogenetic analysis of PYd21-MIP and other MIP sequences from diverse fungi agreed with the current organism phylogeny. Analysis of protein domains by InterProScan software and motif searching demonstrated that PYd21-MIP encodes a homologous MIP protein. These data support the hypothesis that the PYd21-MIP protein is a Hog-MIP protein homologue from V. volvacea.

Heteroglycan from an alkaline extract of a somatic hybrid mushroom (PfloVv1aFB) of Pleurotus florida and Volvariella volvacea: structural characterization and study of immunoenhancing properties.

A water soluble heteroglycan, isolated from the alkaline extract of the fruit bodies of the somatic hybrid mushroom (PfloVv1aFB), raised through protoplast fusion between the strains of Pleorutus florida and Volverilla volvacea, was found to consist of (1→3)-, (1→6)-, (1→3,4)-linked, and terminal ß-D-Glcp along with (1→2,6)-α-D-Galp and terminal α-D-Manp in a relative proportion of approximately 1:1:1:1:1:1. This polysaccharide exhibited strong immunostimulating activity of macrophages as well as splenocytes and thymocytes. Structural investigation was carried out using sugar analysis, methylation analysis; periodate oxidation study, and NMR experiments ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above mentioned experiments, the structure of the repeating unit of the polysaccharide was established as: [formula see text].

Glucans from alkaline extract of a hybrid mushroom (backcross mating between PfloVv12 and Volvariella volvacea): structural characterization and study of immunoenhancing and antioxidant properties.

Two different glucans (water-soluble PS-I, water-insoluble PS-II) were isolated from the alkaline extract of the fruit bodies of hybrid mushroom. PS-I was found to consist of only (1→6)-linked ß-D-glucopyranose. PS-II was composed of terminal, (1→3,4)-linked, and (1→3)-linked ß-D-glucopyranosyl moieties in a molar ratio of nearly 1:1:1. PS-I showed macrophages, splenocytes, and thymocytes activation as well as antioxidant property. On the basis of sugar analysis, methylation analysis, and NMR studies ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC), the structure of the repeating unit of these glucans were established as:

A (1-->6)-beta-glucan from a somatic hybrid of Pleurotus florida and Volvariella volvacea: isolation, characterization, and study of immunoenhancing properties.

A water-soluble immunoenhancing polysaccharide was isolated from the aqueous extract of fruit bodies of somatic hybrid (Pflo Vv5 FB), obtained through protoplast fusion between Pleurotus florida and Volvariella volvacea strains. On the basis of acid hydrolysis, the polysaccharide was found to contain glucose only. Methylation analysis, periodate oxidation along with (1)H, DEPT-135, and (13)C NMR spectroscopy, including two-dimensional TOCSY, DQF-COSY, NOESY, ROESY, 1H,13C-HMQC, and HMBC experiments showed that the polysaccharide was a (1-->6)-beta-d-glucan, which was not a constituent of any of the parent mushrooms previously reported. This glucan stimulated the macrophages, splenocytes, and thymocytes.

Secondary metabolites of Volvariella bombycina and their inhibitory effects on melanogenesis.

Four compounds were isolated from the broth culture of Volvariella bombycina and they were identified as ergosta-4,6,8(14),22-tetraene-3-one (1), ergosterol peroxide (2), indole-3-carboxaldehyde (3) and indazole (4) by interpretation of spectroscopic data. Among them, compound 2 exhibited melanogenesis inhibitory effect in cultured B16 mouse melanoma cells.

Composition of transgenic Volvariella volvacea tolerant to cold stress is equivalent to that of conventional control.

Transgenic Volvariella volvacea strains, which are tolerant to cold stress, were generated by the stable insertion of antifreeze protein gene isolated from budworm into the genome of a conventional variety V23 of V. volvacea. As a part of the safety assessment program, transgenic V. volvacea strains were compared to a nontransgenic near-isogenic V. volvacea strain V23 grown contemporaneously by applying the principle of substantial equivalence. Compositional analyses were conducted by measuring proximates, amino acids, fatty acids, minerals, vitamins, 5'-nucleotides, nucleic acid, and antinutrients such as tannin and cyanide in V. volvacea strains harvested at egg-shaped stage. Results of the comparisons indicate that these transgenic strains are compositionally equivalent to the conventional control.

NMR and MALDI-TOF analysis of a water-soluble glucan from an edible mushroom, Volvariella diplasia.

A polysaccharide (Fr. II) has been isolated from the hot aqueous extract of the fruit bodies of an edible mushroom, Volvariella diplasia. The polysaccharide contains glucose only. On the basis of total acid hydrolysis, methylation analysis, NMR studies ((1)H, (13)C, 2D-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC), and MALDI-TOFMS analysis, the structure of the repeating unit of the polysaccharide was established as formula see text.