Increase in the incidence of invasive fungal infections due to Volvariella Volvacea.

PURPOSE: We aimed to show the increasing incidence of invasive fungal infections due to Volvariella Volvacea in patients with immunosuppression. METHODS: We present a case of an invasive fungal infection caused by Volvariella volvacea, and summarize the clinical and pathological features based on this case and a review of the literature. RESULTS: A total of seven patients with IFIs due to Volvariella Volvacea have been reported in the literature. The majority of cases have been obtained between 2019 and 2022. Including our case, they all had acquired immunosuppression. The lung and brain were the most commonly affected organs. All eight of these patients received antifungal therapy, but five still died one to seven months after occurrences of IFIs. CONCLUSION: The incidence of invasive fungal infections due to Volvariella Volvacea is increasing in recent years. It mainly occurred in patients with immunosuppression, especially in patients with malignant hematological cancers, and increased mortality.

The cold - resistance mechanism of a mutagenic Volvariella volvacea strain VH3 with outstanding traits revealed by transcriptome profiling.

BACKGROUND: The straw mushroom (Volvariella volvacea) is one of the important vegetables that is popular for its delicious taste. However, the straw mushroom is sensitive to low temperature, resulting in economic loss during transportation and storage. We obtained a novel straw mushroom strain, named VH3, via ultraviolet mutagenesis. RESULTS: Our study revealed that VH3 exhibited high cold resistance compared to an ordinary straw mushroom cultivar, V23. We found that the electrolyte leakages of VH3 were always significantly lower than that of V23 treated with 4 °C for 0 h, 2 h,4 h, 8 h, 16 h, and 24 h. Before cold treatment (0 h), there were no difference of MDA contents, SOD activities, and CAT activities between VH3 and V23. At the late stage (8 h, 26 h, and 24 h) of cold treatment, the MDA contents of VH3 were lower while both the SOD and CAT activities were higher than those of V23. To investigate the potential mechanisms of VH3 cold resistance, we performed transcriptome sequencing to detect the transcriptome profiling of VH3 and V23 after 0 h and 4 h cold treatment. Transcriptome sequencing revealed that 111 differentially expressed genes (DEG) between V23 (0 h) and VH3 (0 h) (V23-0_vs_VH3-0), consisting 50 up-regulated and 61 down-regulated DEGs. A total of 117 DEGs were obtained between V23 (4 h) and VH3(4 h) (V23-4_vs_VH3-4), containing 94 up-regulated and 23 down-regulated DEGs. Among these DEGs, VVO_00021 and VVO_00017 were up-regulated while VVO_00003, VVO_00004, VVO_00010, and VVO_00030 were down-regulated in V23-0_vs_VH3-0 and VH3-4_vs_V23-4. KEGG and GO analysis revealed that the 6 DEGs were annotated to pathways related to cold stress. Besides, the GA3 content was also decreased in VH3. CONCLUSIONS: Collectively, our study first revealed that the increased cold resistance of VH3 might be caused by the expression change of VVO_00003, VVO_00004, VVO_00017, VVO_00021, and VVO_00030, and decreased GA3.

Bioconversion of bamboo shoot shells through the cultivation of the edible mushrooms Volvariella volvacea.

Bamboo shoot shell (BSS), as agricultural waste, is mostly burned or discarded, causing serious environment pollution. In this study, the degradation and utilization of BSS by the edible fungus Volvariella Volvacea was investigated. The composition of V. volvacea fruit body was determined by HPLC-MS, GC-MS and ICP-OES. The activities of CMCase and xylanase were monitored by DNS (3,5-dinitrosalicylic acid) method. Laccase activity was assayed by the oxidation reaction of ABTS [2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)]. The degraded bamboo shoot shell powder was characterized by FTIR and SEM. The results showed that the mycelium of V. volvacea could degrade and utilize BSS for growth. The activities of carboxymethyl cellulase and laccase were increased during the cultivation. At the same time, the physical structure of the shell fiber becames porous and rough. Most of the products of decayed fibers contain alkanes, ethyl or methyl groups. Moreover, the biological efficiency (fruiting body yield) of V. volvacea cultivated on BSS was 1.52-fold higher than that of straw cultivation. The contents of total lipid, elaidic acid (C18:1n-9), total essential amino acids, total amino acids and iron in V. volvacea fruit bodies grown on BSS were 1.11, 1.66, 1.52, 1.60 and 1.30-fold higher than those of straw treatment, respectively. This study provides an effective method to solve the environmental pollution caused by BSS, and provides a new way for the potential utilization of BSS in edible fungi cultivation.

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.

Improved fruiting of the straw mushroom (Volvariella volvacea) on cotton waste supplemented with sodium acetate.

Compared with controls, treatment of the cultivation substrate for Volvariella volvacea with 0.02% NaAc at the "spraying water" stage increased the number of fruiting body primordia by 280, the mushroom yield by 16.25%, the number of fruiting bodies by 35.57%, and the biological efficiency by 16.28%. The average single mushroom weight increased by 19.33%, but there was no significant difference between treatments and controls. A correlation analysis revealed a significant (p < 0.05) positive correlation between the total yield and the number of fruiting bodies. Comparisons of the cost and profit values for the sodium acetate-treated and untreated groups revealed that the former generated a higher income for the grower. Our data indicate that sodium acetate treatment is a promising new method for increasing V. volvacea yields. A possible mechanism whereby sodium acetate increased the mushroom yield is discussed.

Analysis of synonymous codon usage patterns in the edible fungus Volvariella volvacea.

In this study, trends in synonymous codons usage of Volvariella volvecea have been first examined by analysis of complete coding sequences and gene chip data. The results showed that GC content at three codon positions are obviously different and there were several factors shaping the codon usage of V. volvacea genes, including base composition. The comparison of codon usage among four edible fungi such as V. volvacea, Agaricus bisporus, Coprinopsis cinerea, and Pleurotus ostreatus indicated that the similar codon usage pattern was used among V. volvacea, A. bisporus and P. ostreatus, but there was significantly different codon usage pattern of C. cinerea. Two arrays of optimal codons were determined by effective number of codons (ENC) values and gene chip database separately, resulting that most of the ENC-predicted optimal codons were included in the array of gene chip resulted optimal codons. This study can provide useful information for codon usage pattern analysis and gene transformation of V. volvacea.

Identification and physiological properties of a Nigerian strain of Volvariella sp. isolated from oil palm waste.

Over the years several species of edible mushrooms have been collected for consumption from different agro-wastes in Nigeria. Identification of most of these mushrooms was often by morphological descriptive methods. This study reports the morphological study, physiological study and identification of a Nigerian wild strain of Volvariella sp. (VNW) isolated from discarded oil palm waste and three Indian commercial strains V11, V245 and V247 of V. volvacea. Effect of incubation temperatures and medium pH was investigated. Molecular characterization of the strains was carried out using ITS-1 and ITS-4 primers. Results obtained showed close similarities of the Nigerian strain to the Indian strains with few morphological variations in colour, shape and appearance. Growth was observed at temperature range of 20-40 °C and pH range of 4.0-8.0 for all strains with optimum mycelia extension at 35 °C and pH 6.0. VNW recorded a significantly higher (p ≤ 0.05) mycelia extension rate at 35 °C (25.20 ± 1.80 mm/day) and pH 6.0 (40.20 ± 0.34 mm/day). Highest biomass yield was observed at pH 6.0 with V11 recording a significantly (p ≤ 0.05) higher yield (1.74 ± 0.07 g/100 mL). Increasing percentage (w/v) of CaSO4·H2O increased biomass yield of all the strains. NJ phylogenetic tree showed the Nigerian and Indian strains in the same cluster indicating evolutionary closeness than with other species of Volvariella from GenBank in a separate cluster even though they share a common ancestor. This successfully proves the identity of a Nigerian strain of Volvariella sp. VNW from oil palm waste as V. volvacea with GenBank accession number KC894923.

A new approach for breeding low-temperature-resistant Volvariella volvacea strains: Genome shuffling in edible fungi.

Volvariella volvacea is difficult to store fresh because of the lack of low-temperature resistance. Many traditional mutagenic strategies have been applied in order to select out strains resistant to low temperature, but few commercially efficient strains have been produced. In order to break through the bottleneck of traditional breeding and significantly improve low-temperature resistance of the edible fungus V. volvacea, strains resistant to low temperature were constructed by genome shuffling. The optimum conditions of V. volvacea strain mutation, protoplast regeneration, and fusion were determined. After protoplasts were treated with 1% (v/v) ethylmethylsulfonate (EMS), 40 Sec of ultraviolet (UV) irradiation, 600 Gy electron beam implantation, and 750 Gy60 Co-γ irradiation, separately, the lethality was within 70%-80%, which favored generating protoplasts being used in following forward mutation. Under these conditions, 16 strains of V. volvacea mutated by EMS, electron beam, UV irradiation, and 60 Co-γ irradiation were obtained. The 16 mutated protoplasts were selected to serve as the shuffling pool based on their excellent low-temperature resistance. After four rounds of genome shuffling and low-temperature resistance testing, three strains (VF1 , VF2 , and VF3 ) with high genetic stability were screened. VF1 , VF2 , and VF3 significantly enhanced fruit body shelf life to 20, 28, and 28 H at 10 °C, respectively, which exceeded 25%, 75%, and 75%, respectively, compared with the storage time of V23, the most low-temperature-resistant strain. Genome shuffling greatly improved the low-temperature resistance of V. volvacea, and shortened the course of screening required to generate desirable strains. To our knowledge, this is the first paper to apply genome shuffling to breeding new varieties of mushroom, and offers a new approach for breeding edible fungi with optimized phenotype.

Endoglucanase enzymatic modification of kraft pulp during recycling.

OBJECTIVE: To investigate the cellulose modification process on kraft pulp during recycling by mono-endoglucanase. RESULTS: Pichia pastoris expressing endoglucanase, EG1, was grown in a 10 l fermenter yielding a high carboxymethyl cellulase (CMCase) activity of 340 U mg(-1). EG1-mediated modification of kraft pulp resulted in a paper sheet with the tensile index and burst index increased by 10 and 6.5 %, respectively. The kink index (indicating abrupt bends in fibres) of the enzyme-treated group decreased sharply by 45 % after the first recycling, compared with a reduction of only 1 % in the control group. Furthermore, EG1 treatment decreased the growth of crystallinity from 73.5 to 73.2 % and crystal size from 7.45 to 7.21 nm, which alleviated paper aging. CONCLUSION: Endoglucanase EG1 modifies the interfacial properties of fibers, which affects fibre morphology during the recycling process and improves the technical properties of the resulting pulp and paper.

A specific type of cyclin-like F-box domain gene is involved in the cryogenic autolysis of Volvariella volvacea.

Cryogenic autolysis is a typical phenomenon of abnormal metabolism in Volvariella volvacea. Recent studies have identified 20 significantly up-regulated genes via high-throughput sequencing of the mRNAs expressed in the mycelia of V. volvacea after cold exposure. Among these significantly up-regulated genes, 15 annotated genes were used for functional annotation cluster analysis. Our results showed that the cyclin-like F-box domain (FBDC) formed the functional cluster with the lowest P-value. We also observed a significant expansion of FBDC families in V. volvacea. Among these, the FBDC3 family displayed the maximal gene expansion in V. volvacea. Gene expression profiling analysis revealed only one FBDC gene in V. volvacea (FBDV1) that was significantly up-regulated, which is located in the FBDC3 family. Comparative genomics analysis revealed the homologous sequences of FBDV1 with high similarity were clustered on the same scaffold. However, FBDV1 was located far from these clusters, indicating the divergence of duplicated genes. Relative time estimation and rate test provided evidence for the divergence of FBDV1 after recent duplications. Real-time RT-PCR analysis confirmed that the expression of the FBDV1 was significantly up-regulated (P < 0.001) after cold-treatment of V. volvacea for 4 h. These observations suggest that the FBDV1 is involved in the cryogenic autolysis of V. volvacea.

Cloning and Expression Analysis of Vvlcc3, a Novel and Functional Laccase Gene Possibly Involved in Stipe Elongation.

Volvariella volvacea, usually harvested in its egg stage, is one of the most popular mushrooms in Asia. The rapid transition from the egg stage to elongation stage, during which the stipe stretches to almost full length leads to the opening of the cap and rupture of the universal veil, and is considered to be one of the main factors that negatively impacts the yield and value of V. volvacea. Stipe elongation is a common phenomenon in mushrooms; however, the mechanisms, genes and regulation involved in stipe elongation are still poorly understood. In order to study the genes related to the stipe elongation, we analyzed the transcription of laccase genes in stipe tissue of V. volvacea, as some laccases have been suggested to be involved in stipe elongation in Flammulina velutipes. Based on transcription patterns, the expression of Vvlcc3 was found to be the highest among the 11 laccase genes. Moreover, phylogenetic analysis showed that VvLCC3 has a high degree of identity with other basidiomycete laccases. Therefore, we selected and cloned a laccase gene, named Vvlcc3, a cDNA from V. volvacea, and expressed the cDNA in Pichia pastoris. The presence of the laccase signature L1-L4 on the deduced protein sequence indicates that the gene encodes a laccase. Phylogenetic analysis showed that VvLCC3 clusters with Coprinopsis cinerea laccases. The ability to catalyze ABTS (2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) oxidation proved that the product of the Vvlcc3 gene was a functional laccase. We also found that the expression of the Vvlcc3 gene in V. volvacea increased during button stage to the elongation stage; it reached its peak in the elongation stage, and then decreased in the maturation stage, which was similar to the trend in the expression of Fv-lac3 and Fv-lac5 in F. velutipes stipe tissue. The similar trend in expression level of these laccase genes of F. velutipes suggested that this gene could be involved in stipe elongation in V. volvacea.

Structural Variation (SV) Markers in the Basidiomycete Volvariella volvacea and Their Application in the Construction of a Genetic Map.

Molecular markers and genetic maps are useful tools in genetic studies. Novel molecular markers and their applications have been developed in recent years. With the recent advancements in sequencing technology, the genomic sequences of an increasingly great number of fungi have become available. A novel type of molecular marker was developed to construct the first reported linkage map of the edible and economically important basidiomycete Volvariella volvacea by using 104 structural variation (SV) markers that are based on the genomic sequences. Because of the special and simple life cycle in basidiomycete, SV markers can be effectively developed by genomic comparison and tested in single spore isolates (SSIs). This stable, convenient and rapidly developed marker may assist in the construction of genetic maps and facilitate genomic research for other species of fungi.

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.

The combination of high oxygen and nanocomposite packaging alleviated quality deterioration by promoting antioxidant capacity and phenylpropane metabolism in Volvariella volvacea.

Volvariella volvacea is a highly perishable mushroom that severely affects its postharvest commercial value. This study aimed to investigate the impact of high oxygen (O2) levels combined with nanocomposite packaging on the shelf-life quality of V. volvacea. Results showed that treatment with high concentrations of O2 (80% and 100% O2) and nanocomposite packaging effectively delayed the quality deterioration of V. volvacea, resulting in better postharvest appearance, higher firmness, lower weight loss, malondialdehyde (MDA) content, and leakage of membrane electrolytes. Further analysis revealed the combination treatments ameliorated oxidative stress by inducing antioxidant enzymes and the glutathione-ascorbate (GSH-AsA) cycle at both enzymatic and transcriptional levels, thereby activating the antioxidant system. Additionally, the treatments enhanced activities of key enzymes in phenylpropane metabolism, leading to a reduction in the decrease of total phenolics and flavonoids. This work provides new insights into the development of postharvest technologies to prolong the storage life of V. volvacea.

Structural characterization and anti-oxidant activity of polysaccharide HVP-1 from Volvariella volvacea.

In this study, a novel homogeneous polysaccharide (HVP-1) was purified from the Volvariella volvacea. Its structural characteristics and anti-oxidant activity in vitro were further evaluated. The results revealed that HVP-1 was composed of mannose, glucose, galactose and arabinose in a molar ratio (mol %) of 55.37: 15.74: 25.20: 3.69. Its main chain consisted of →4)-ß-D-Galp-(1→, →6)-α-D-Glcp-(1→, →3)-α-D-Glcp-(1→, →4)-ß-D-Manp-(1→ and →3,6)-ß-D-Manp-(1→. The branched structure α-L-Araf-(1→, →2)-ß-D-Glcp-(1→ and →6)-ß-D-Manp-(1→ were connected to →3,6)-ß-D-Manp-(1→ through the O-3 position. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that HVP-1 had porous sheet-like structure with a triple helix conformation. Anti-oxidant activity experiments showed that HVP-1 alleviated H2O2-induced oxidative damage by reducing the accumulation of reactive oxygen species, increasing the activity of related enzymes in cells, and activating the Nrf2/HO-1 signaling pathway. These results suggested that HVP-1 had the potential to be used as a natural anti-oxidant in functional foods and pharmaceuticals.

[Effect of VvLaeA on the growth and development of Beauveria bassiana].

It is unclear how VvLaeA functions in regulating the growth and development of Volvariella volvacea (Bull. ex. Fr.) Sing.. Firstly, bioinformatics analysis of VvLaeA was carried out in this study. Subsequently, the Vvgpd promoter and the open reading frame (ORF) fragment of VvlaeA were amplified and fused by polymerase chain reaction (PCR). The fusion fragment was cloned into the pK2 (bar) plasmid. The recombinant construct pK2(bar)-OEVvlaeA was transfected into Beauveria bassiana by Agrobacterium tumefaciens-mediated transformation. Finally, the growth and development of the transformants were examined. The results showed that VvLaeA shared a low homology with similar proteins in other fungi. Compared with the wild type, the colony diameter of the transformant was significantly increased. However, the pigment deposition, conidial yields and germination rates were significantly decreased. The overexpression strains were more sensitive to stresses than that of the wild type. Further studies showed the conidial cell wall properties of the transformants were altered, and the expressions of genes related to the conidial development were significantly down-regulated. Collectively, VvLaeA increased the growth rate of B. bassiana strains and negatively regulated the pigmentation and conidial development, which shed a light for the functional identification of straw mushroom genes.

Impact of high pressure pre-treatment and hot water extraction on chemical properties of crude polysaccharide extract obtained from mushroom (Volvariella volvacea).

An examination of the process of extracting crude polysaccharides from Volvariella volvacea solely through hot water treatment (HWE) at 60, 80, and 100 °C and through an approach involving high pressure processing (HPP) at 200, 400, and 600 MPa followed by HWE. The physiological properties of the polysaccharides could be explained by the structural analysis performed via FT-IR spectroscopy and NMR spectroscopy, which revealed the extract composition of the protein-bound polysaccharides connected by ß-glycosidic bonds. Under the extraction conditions investigated in this current study, the recommended extraction condition was a combination of HPP (600 MPa, 10 min) and HWE (60 °C, 2 h). This condition gave high crude polysaccharide yields (with a 2-12% increase), and ß-glucan content (with a 15-20% increase) without disrupting the ß-glycosidic bond, as compared to using HWE alone. High pressure extraction could be an alternative technique for reduced extraction temperatures of active compounds from mushrooms.

Oxidative damage from repeated tissue isolation for subculturing causes degeneration in Volvariella volvacea.

The fungal fruiting body is the organized mycelium. Tissue isolation and mycelium succession are common methods of fungal species purification and rejuvenation in the production of edible mushrooms. However, repeated succession increases strain degeneration. In this study, we examined the effect of repeated tissue isolation from Volvariella volvacea fruitbodies on the occurrence of degeneration. The results showed that less than four times in succession improved production capacity, however, after 12 successions, the traits indicating strain degeneration were apparent. For instance, the density of aerophytic hyphae, hyphal growth rate and hyphal biomass were gradually reduced, while the hyphae branching was increased. Also, other degenerative traits such as prolonged production cycles and decreased biological efficiency became evident. In particular, after 19 successions, the strain degeneration became so severe no fruiting bodies were produces anymore. Meanwhile, with the increase in successions, the antioxidant enzyme activity decreased, reactive oxygen species (ROS) increased, the number of nuclei decreased, and the mitochondrial membrane potential decreased along with morphological changes in the mitochondria. This study showed that repeated tissue isolation increased oxidative damage in the succession strain due to the accumulation of ROS, causing cellular senescence, in turn, degeneration in V. volvacea strain.

Structural Characteristics and Multiple Bioactivities of Volvariella volvacea Polysaccharide Extracts: The Role of Extractive Solvents.

The chemical structures and functional properties of plant-based polysaccharides are critically influenced by extractive solvents, but their roles are not clear. In this study, the structural characteristics and multiple bioactivities of Volvariella volvacea polysaccharides (VVPs) subjected to water (VVP-W), alkalis (sodium hydroxide, VVP-A), and acids (citric acid, VVP-C) as extractive solvents are investigated systematically. Of the above three polysaccharides, VVP-W exhibited the highest molecular weights, apparent viscosity, and viscoelastic properties. Functional analyses revealed that VVP-C had an excellent water-holding capacity, foaming properties, and emulsifying capacity, while VVP-A exhibited a promising oil-holding capacity. Moreover, VVP-C displayed strong inhibitory effects on α-amylase and α-glucosidase, which could be attributed to its content of total phenolics, proteins, and molecular weights. These findings have important implications for selecting the appropriate extraction techniques to obtain functional polysaccharides with targeted bioactive properties as food additives.

Effects of in vitro simulated digestion and fecal fermentation of polysaccharides from straw mushroom (Volvariella volvacea) on its physicochemical properties and human gut microbiota.

Herein, the fermentation and digestion behavior of Volvariella volvacea polysaccharide (VVP) were examined through the in vitro simulation experiment. The results revealed that succeeding the simulated salivary gastrointestinal digestion, the molecular weight of VVP was reduced by only 8.9 %. In addition, the reducing sugar, uronic acid, monosaccharide composition and Fourier transform infrared spectroscopy characteristics of VVP did not change significantly, which indicate that saliva-gastrointestinal could not digest VVP. However, 48 h of fecal fermentation of VVP dramatically reduced its molecular weight by 40.4 %. Furthermore, the molar ratios of the monosaccharide composition altered considerably due to the degradation of VVP by microorganisms and the metabolysis into different short-chain fatty acids (SCFAs). Meanwhile, the VVP also raised the proportion of Bacteroidetes to Firmicutes and promoted the proliferation of some beneficial bacteria including Bacteroides and Phascolarctobacterium, whereas it inhibited the growth of unfavorable bacteria such as Escherichia-shigella. Therefore, VVP has the potential to have a positive influence on health and hinder diseases by improving the intestinal microbial environment. These findings provide a theoretical foundation to further develop Volvariella volvacea as a healthy functional food.