Physiological studies of exopolysaccharide production from the basidiomycete Pleurotus sp. florida

Pleurotus spp. Mycelia Enriched in Magnesium and Zinc Salts as a Potential Functional Food

Worldwide, mushrooms belonging to the Pleurotus spp. such as P. citrinopileatus, P. djamor, and P. pulmonarius are highly valued not only for their taste and aroma but also for their health-promoting properties. These species are rich in bioelements, vitamins, and above all, compounds that exhibit immunostimulatory activity. Therefore, in this study, we aimed to determine the effect of the supplementation of culture media using inorganic Mg and Zn salts. This is the first study to establish the bioavailability of the selected elements (Mg and Zn) and anions (Cl⁻, SO₄²⁻) from the enriched biomass by means of the extraction of lyophilized mycelium into artificial digestive juices. The following salts were added to the liquid Oddoux medium: ZnSO₄·7H₂O, ZnCl₂, MgSO₄·7H₂O or MgCl₂·6H₂O. The bioelements, anions and organic compounds in the obtained biomass were determined. The addition of Zn and Mg salts to the media increased the production of biomass by 30% and increased the bioaccumulation of the inorganic salts. Maintaining in vitro cultures under optimized and controlled conditions produced mycelium with a better composition and health properties than otherwise. Such enriched biomass may be classified as potential functional foods, aiding in overcoming deficiencies of elements and organic compounds with biological activity in humans.

Exopolysaccharides from Basidiomycota: Formation, isolation and techno-functional properties

This Mini Review gives an overview of and respective references for the production and properties of exopolysaccharides from Basidiomycota in submerged cultivation. Media and conditions that are usually applied in laboratory culture are summarized, and the lack of studies related to up-scaling is addressed. Procedures for isolation and purification of the exopolysaccharides from the fermentation media are reviewed, and challenges related to exopolysaccharide quantification are discussed. Finally, the techno-functional properties of the respective exopolysaccharides, and potential applications in foods are addressed.

A polysaccharide fraction extracted from Pleurotus ostreatus mycelial biomass inhibit Sarcoma 180 tumor

Fungi of Pleurotus genus have attracted a great interest due to their medicinal properties such as anti-inflammatory, antimicrobial and antitumor. These properties are attributed mainly to polysaccharides synthesized by Pleurotus. This work aimed to study the mycelial growth of P. ostreatus in submerged culture, evaluating the influence of the initial concentration of substrate (20 and 40 g/L of glucose) and the pH (4 and 6) on kinetic parameters of production of biomass. The effectiveness of different doses (10, 30 and 50 mg/kg) of a mycelium polysaccharide fraction extracted from P. ostreatus in reducing Sarcoma 180 development in mice was also verified. In the range of this study, maximum concentration of mycelial biomass (about 12.8 g/L) was obtained using 40.0 g/L of glucose, at pH 4.0. The total biomass productivity (Px) was not significantly affected by substrate concentration and pH, reaching values of 0.034 g/L.h. Sarcoma 180 tumor weight was reduced in 74.1, 75.5 and 53.7% when 10, 30 and 50 mg/kg were administered, respectively. These results show the high antitumor potential of intracellular polysaccharide fraction of mycelial biomass of P. ostreatus, particularly at lower doses of 10 and 30 mg/kg.

Preparation of intracellular proteins from a white-rot fungus surrounded by polysaccharide sheath and optimization of their two-dimensional electrophoresis for proteomic studies

The functions and properties of fungal sheath, an extracellular polysaccharide produced by many white-rot fungi, have been studied. However, the strong adherence of the sheath to fungal hyphae had been a major impediment in preparing intracellular proteins from the fungi and analyzing their cellular responses. To overcome this issue, we developed a rapid and easy method to remove the polysaccharide sheath using a selective lignin degrader, Ceriporiopsis subvermispora, which produces large sheath amounts in the presence of a lignin-derived aromatic compound. Using this approach, we achieved thorough removal of sheath and cell disruption using beads and a solution with a high protein-solubilizing power, which enabled the efficient extraction of intracellular proteins from C. subvermispora surrounded by sheath. In addition, for proteomic analysis, we investigated whether these extracted proteins were compatible with two-dimensional electrophoresis. By efficiently concentrating on protein solubilization in the first dimension and using a stacking gel in the second dimension, we successfully obtained a high-resolution proteome map of C. subvermispora. We also used the same proteins for fluorescence two-dimensional difference gel electrophoresis to obtain the quantitative protein expression profiles. These steps demonstrated that two-dimensional electrophoresis-based proteomics can be used to clarify the composition of intracellular proteins from sheath-producing white-rot fungi.

Isolation and characterization of extracellular polysaccharide Thelebolan produced by a newly isolated psychrophilic Antarctic fungus Thelebolus

The present investigation is on a newly isolated psychrophilic Antarctic filamentous Ascomycetous fungus that has been identified as Thelebolus sp. and given the designation of Thelebolus sp. IITKGP-BT12. The culture was primarily identified through morphological studies, and was further confirmed by 18S rRNA sequencing (GenBank Accession No. KC191572), which revealed its close relatedness with Thelebolus microsporus. The exopolysaccharide (EPS) produced (1.94 g L(-1)) by the fungus was isolated, purified and characterized as glucan having an average molecular mass of 5×10(5)Da. The structure of EPS was determined by gas chromatography with tandem mass spectrometry (GC-MS/MS), Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) studies ((1)H, (13)C and HSQC). NMR analysis indicated the presence of (1→3)-linked β-d-glucan backbone with (1→6)-linked branches of β-d-glucopyranosyl units. Antiproliferative activity of EPS was demonstrated in B16-F0 cells, with IC50 of 275.42 μg m L(-1). Flow cytometry analysis and DNA fragmentation studies revealed that the cytotoxic action of the EPS mediated apoptosis in cancer cells. This is the first ever report on bioactive EPS thelebolan from Thelebolus sp.

Alternative medium for production of Pleurotus ostreatus biomass and potential antitumor polysaccharides

Pleurotus species are recognized for producing beta-glucans with important medicinal properties as a constituent of the cellular wall of the fruiting body or of the mycelium. The aims of this work were to select a culture medium that maximized the production of biomass and polysaccharides produced by Pleurotus ostreatus DSM 1833 and to evaluate the selected medium in two values of initial oxygen transfer rate -K(L)a (10.2 and 19.3 h(-1)). A 2* *4 factorial design was constructed to evaluate the supplementation of wheat extract with corn steep liquor--CSL (10 or 20 g L(-1)), yeast extract--YE (2 or 5gL(-1)), ammonium sulfate--AS (0 or 5 g L(-1)) and glucose (20 or 40 g L(-1)). In terms of maximum productivity in biomass and global productivity in polysaccharides, the best values were obtained when 5 g L(-1) of YE and 40 g L(-1) of glucose were used. In terms of maximum concentration of biomass, the best results were obtained when 20 g L(-1) of CSL and 40 g L(-1) of glucose were used. The best results in terms of production of biomass and polysaccharides were achieved when lower initial K(L)a (10.2 h(-1)) was used.

Characterisation of the extracellular polysaccharides produced by isolates of the fungus Acremonium

Solid state (13)C NMR studies of the extracellular glucans from the fungi Acremonium persicinum C38 (QM107a) and Acremonium sp. strain C106 indicated a backbone of (1-->3)-beta-linked glucosyl residues with single (1-->6)-beta-linked glucosyl side branches for both glucans. Analyses of enzymatic digestion products suggested that the average branching frequency for the A. persicinum glucan (66.7% branched) was much higher than that of the Acremonium sp. strain C106 glucan (28.6% branched). The solid state (13)C NMR spectra also indicated that both glucans are amorphous polymers with no crystalline regions, and the individual chains are probably arranged as triple helices.

A partially 3-O-methylated (1-->4)-linked alpha-D-galactan and alpha-D-mannan from Pleurotus ostreatoroseus Sing

The two main water-soluble extracellular polysaccharides produced by the basidiomycete fungus Pleurotus ostreatoroseus Sing were isolated and purified. They were characterized using 13C, 1H, and 1H, 13C HMQC NMR spectroscopy, methylation analysis, and Smith degradation. One was a mannan having a main chain of (1-->6)-linked alpha-D-mannopyranosyl residues, almost all of which were branched at O-2 with side chains of different lengths, containing 2-O- and 3-O-linked mannopyranosyl units. The other was a partially 3-O-methylated (1-->4)-linked alpha-D-galactopyranan, a structure that has not been previously described.

Screening of basidiomycetes for the production of exopolysaccharide and biomass in submerged culture

Fifty-six strains of Basidiomycetes, including native Brazilian fungi isolated from different ecosystems and edible mushrooms, were screened for production of exopolysaccharides and biomass in submerged culture. Agaricus sp. (CCB 280) and Oudemansiella canarii (Jungh.) Hohn (CCB 179) were the highest exopolysaccharide producers (6.01 and 3.54 g dry w./l respectively) after 7 days of incubation. The best producer of biomass was Schizophyllum commune Fr.:Fr. (CCB 473) with 16.68 g dry w./l in 14 days of incubation. When the culture filtrate was submitted to freezing prior to polysaccharide precipitation, a gelatinous fraction was formed.

Electron and fluorescence microscopy of extracellular glucan and aryl-alcohol oxidase during wheat-straw degradation by Pleurotus eryngii

The ligninolytic fungus Pleurotus eryngii grown in liquid medium secreted extracellular polysaccharide (87% glucose) and the H2O2-producing enzyme aryl-alcohol oxidase (AAO). The production of both was stimulated by wheat-straw. Polyclonal antibodies against purified AAO were obtained, and a complex of glucanase and colloidal gold was prepared. With these tools, the localization of AAO and extracellular glucan in mycelium from liquid medium and straw degraded under solid-state fermentation conditions was investigated by transmission electron microscopy (TEM) and fluorescence microscopy. These studies revealed that P. eryngii produces a hyphal sheath consisting of a thin glucan layer. This sheath appeared to be involved in both mycelial adhesion to the straw cell wall during degradation and AAO immobilization on hyphal surfaces, with the latter evidenced by double labelling. AAO distribution during differential degradation of straw tissues was observed by immunofluorescence microscopy. Finally, TEM immunogold studies confirmed that AAO penetrates the plant cell wall during P. eryngii degradation of wheat straw.

Structural characterization of extracellular polysaccharides produced by fungi from the genus Pleurotus

The extracellular polysaccharides produced in liquid cultures of the ligninolytic fungi Pleurotus cornucopiae, P. eryngii, P. floridanus, P. ostreatus, P. pulmonarius and P. sajor-caju showed similar composition and structure. They included a minor water-soluble fraction, containing D-glucose, D-mannose, D-galactose and protein (rich in amide- and hydroxyl-containing residues which can be involved in protein-polysaccharide linkages). The structural analysis of this fraction mainly showed alpha-(1-->4)-linked glucose units. The structure of the major fraction (amounting to more than 80% of the total extracellular polysaccharide) was investigated in detail. Its low solubility was attributed to the high M(r). For its characterization a procedure of progressive dissolution and dialysis was set up. The methylation analysis showed that it was a (1-->3)-beta-D-glucan and that approximately 25% of the total units were C-6 branched. This result was confirmed by the intensities of the signals assigned to C-3 and C-6, free and substituted, in 13C-NMR spectra. Additional studies showed linear polysaccharides after one-cycle Smith degradation or after glucan acetolysis. Both results, as well as glucose release after the latter treatment, indicated that the C-6 linked side chains are constituted by single glucose residues, on every second or third unit of the main chain of the (1-->3)-beta-D-glucan.