iTRAQ-based quantitative proteome revealed metabolic changes of Flammulina velutipes mycelia in response to cold stress.

Temperature is one of the pivotal factors influencing mycelium growth and fruit-body formation of Flammulina velutipes. To gain insights into hyphae growth and fruit-body formation events and facilitate the identification of potential stage-specific biomarker candidates, we investigated the proteome response of F. velutipes mycelia to cold stresses using iTRAQ-coupled two-dimensional liquid chromatography tandem mass spectrometry (2D LC-MS/MS) technique. Among 1198 proteins identified with high confidence, a total of 63 displayed altered expression level after cold stress treatments. In-depth data analysis reveals that differentially expressed proteins were involved in a variety of cellular processes, particularly metabolic processes. Among the 31 up-regulated proteins, 24 (77.42%) were associated with 22 specific KEGG pathways. These up-regulated proteins could possibly serve as potential biomarkers to study the molecular mechanisms of F. velutipes mycelia response to cold stresses. These data of the proteins might provide valuable evidences to better understand the molecular mechanisms of mycelium resistance to cold stress and fruit-body formation in fungi. BIOLOGICAL SIGNIFICANCE: Low-temperature is one of the pivotal factors in some Flammulina velutipes industrial processes influencing mycelium growth, inducing primordia and controlling fruit-body development. Preliminary study has indicated that effectively regulating cultivation could augment the yield by controlling optimal cold stress level on mycelia. However, we are still far from understanding the molecular and physiological mechanisms of adaptation of these fungi at cold stress. In the present study, the experiments reported above were undertaken to investigate chronological changes of protein expression during F. velutipes mycelia in response to cold stress by using iTRAQ-coupled 2D LC-MS/MS technique. This result would provide new insights to the underlying mycelium growth and fruit-body formation mechanisms of basidiomycetes under cold stress.

Flammulina velutipes: An option for "alperujo" use.

BACKGROUND: Two-phase olive-mill wastes (or "alperujo") exhibit highly phytotoxic properties, mainly due to phenols. A valuable option for alperujo is its agricultural use, provided that no phytotoxic effects occur. AIMS: The present investigation was aimed at evaluating the efficacy of two strains of the lignin-degrading fungus Flammulina velutipes to colonize alperujo in order to produce edible mushrooms and to achieve its detoxification. METHODS: Some important cultural characters related to mushroom production (earliness, biological efficiency and quality of basidiomes) were estimated. The production of lignocellulolytic enzymes, phenol removal and detoxification of the substrate was evaluated. RESULTS: High biological efficiencies (70.8%) were obtained at 12°C with F. velutipes strain BAFC 670/06 in a substrate containing poplar wood shavings and 90% of alperujo. The nature of the substrate did not seem to exert an important influence on pileus and stem morphology; nevertheless shortest stems were observed at higher temperatures. Endo-ß-1,4-glucanase, endo-ß-1,4-xylanase, laccase and Mn-peroxidase activities were detected in the extracts recovered from the solid-state cultures. Both F. velutipes strains were effective in removing the phenolic compounds. The initial concentration in the substrate with 90% alperujo was reduced in the case of F. velutipes BAFC 1763 by 84.31%, and 40.15% by F. velutipes BAFC 670/06. Germinability experiments on Raphanus sativus, showed that alperujo phytotoxicity was significantly reduced by F. velutipes cultures. CONCLUSIONS: The experimented changes by the spent mushroom substrate resulting from F. velutipes cultivation with high amount of alperujo would allow its reuse for agricultural purposes.

Removal of Cu2+ ions from aqueous solution by the abandoned mushroom compost of Flammulina velutipes.

The abandoned mushroom compost of Flammulina velutipes, a cheap and easy by-product to get, was used as biosorbent for removing copper ions from aqueous solution. Batch experiments were carried out to investigate the effect of contact time, solution pH, biomass dosage, initial concentration of Cu2+ ions and temperature on biosorption efficiency. The maximum sorption capacity could be reached at pH 5.0 in 60 min. Langmuir, Freundlich, and Redlich- Peterson isotherm models were used to fit the experimental data and their model parameters were evaluated. The calculated qm based on Langmuir equation was 35.608 mg g(-1) at 288 K, 48.711 mg g(-1) at 298 K, and 42.330 mg g(-1) at 308 K, respectively. The kinetics were discussed by pseudo- first order and pseudo-second order models, and the result showed that the latter was more suitable. The thermodynamics of biosorption was also investigated, and the biosorption process was feasible, spontaneous and endothermic in nature.

Comparative genomics of the mating-type loci of the mushroom Flammulina velutipes reveals widespread synteny and recent inversions.

BACKGROUND: Mating-type loci of mushroom fungi contain master regulatory genes that control recognition between compatible nuclei, maintenance of compatible nuclei as heterokaryons, and fruiting body development. Regions near mating-type loci in fungi often show adapted recombination, facilitating the generation of novel mating types and reducing the production of self-compatible mating types. Compared to other fungi, mushroom fungi have complex mating-type systems, showing both loci with redundant function (subloci) and subloci with many alleles. The genomic organization of mating-type loci has been solved in very few mushroom species, which complicates proper interpretation of mating-type evolution and use of those genes in breeding programs. METHODOLOGY/PRINCIPAL FINDINGS: We report a complete genetic structure of the mating-type loci from the tetrapolar, edible mushroom Flammulina velutipes mating type A3B3. Two matB3 subloci, matB3a that contains a unique pheromone and matB3b, were mapped 177 Kb apart on scaffold 1. The matA locus of F. velutipes contains three homeodomain genes distributed over 73 Kb distant matA3a and matA3b subloci. The conserved matA region in Agaricales approaches 350 Kb and contains conserved recombination hotspots showing major rearrangements in F. velutipes and Schizophyllum commune. Important evolutionary differences were indicated; separation of the matA subloci in F. velutipes was diverged from the Coprinopsis cinerea arrangement via two large inversions whereas separation in S. commune emerged through transposition of gene clusters. CONCLUSIONS/SIGNIFICANCE: In our study we determined that the Agaricales have very large scale synteny at matA (∼350 Kb) and that this synteny is maintained even when parts of this region are separated through chromosomal rearrangements. Four conserved recombination hotspots allow reshuffling of large fragments of this region. Next to this, it was revealed that large distance subloci can exist in matB as well. Finally, the genes that were linked to specific mating types will serve as molecular markers in breeding.

Selenium accumulation in mycelia of Flammulina velutipes during fermentation determined by RP-HPLC.

A method to estimate the content of selenium in organics was introduced based on reversed phase-high performance liquid chromatography (RP-HPLC).The maximum absorption peak of piazselenol was at 330 nm and the optimized temperature and pH value were 40 degrees C and 2.8, respectively. The minimum detection concentration of selenium(IV) was 0.06 microg/mL and the measurable range was 0.12-12.0 microg/mL. The organic selenium accumulation in golden needle mushroom (Flammulina velutipes) mycelia was obtained by subtracting the amount of inorganic selenium from that of total selenium. The organic selenium accumulation of various inoculation amounts showed that organic selenium accumulation in a unit volume of the fermentation broth was positively related the inoculation amount. Compared with the methods reported previously, the method used here is simple, reliable and less toxic.