Pleurotus Ostreatus Mycelium Research Articles

Different volatile compounds from mycelium and sporocarp of Pleurotus ostreatus

Different volatile compounds from mycelium and sporocarp of Pleurotus ostreatus

Patterns and dynamics of 32P-phosphate and labelled 2-aminoisobutyric acid ( 14C-AIB) translocation in intact basidiomycete mycelia

Following uptake of 32P-orthophosphate and 14C-aminoisobutyric acid ( 14C-AIB) the patterns of distribution of the isotopes through intact basidiomycete mycelia were non-destructively mapped at regular intervals using a β-scanner. Analysis of the results suggests that translocation of 32P and 14C-AIB through mycelia of Pleurotus ostreatus and Schizophyllum commune occurred along a restricted number of clearly defined, but macroscopically invisible, routes through the mycelium. In contrast to this, 32P added to mycelia of Coprinus cinereus remained immobilised at the addition point. Simultaneous acropetal and basipetal translocation of 32P and 14C-AIB was observed in different regions of colonies of P. ostreatus and S. commune. Translocation of label around the periphery of colonies strongly suggested the existence of anastomoses around the colony margin. Both 32P and 14C-AIB were initially immobilised at the addition point, from which each was subsequently translocated to other parts of the mycelium. The observed translocation of nutrients could not be explained by simple diffusion alone. The velocity of translocation and the complexity of the translocation pattern of 32P were greatest in mycelia of P. ostreatus, a hardwood decomposer, followed by S. commune, a wood and litter decomposer and parasite. Translocation through mycelia of C. cinereus, a coprophilus saprophyte, was very slow. This study provides the first detailed description of nutrient translocation through intact, entire fungal mycelia over time.

Patterns and dynamics of 32P-phosphate and labelled 2-aminoisobutyric acid (14C-AIB) translocation in intact basidiomycete mycelia

Following uptake of 32P-orthophosphate and 14C-aminoisobutyric acid (14C-AIB) the patterns of distribution of the isotopes through intact basidiomycete mycelia were non-destructively mapped at regular intervals using a β-scanner. Analysis of the results suggests that translocation of 32P and 14C-AIB through mycelia of Pleurotus ostreatus and Schizophyllum commune occurred along a restricted number of clearly defined, but macroscopically invisible, routes through the mycelium. In contrast to this, 32P added to mycelia of Coprinus cinereus remained immobilised at the addition point. Simultaneous acropetal and basipetal translocation of 32P and 14C-AIB was observed in different regions of colonies of P. ostreatus and S. commune. Translocation of label around the periphery of colonies strongly suggested the existence of anastomoses around the colony margin. Both 32P and 14C-AIB were initially immobilised at the addition point, from which each was subsequently translocated to other parts of the mycelium. The observed translocation of nutrients could not be explained by simple diffusion alone. The velocity of translocation and the complexity of the translocation pattern of 32P were greatest in mycelia of P. ostreatus, a hardwood decomposer, followed by S. commune, a wood and litter decomposer and parasite. Translocation through mycelia of C. cinereus, a coprophilus saprophyte, was very slow. This study provides the first detailed description of nutrient translocation through intact, entire fungal mycelia over time.

Double-stranded RNA mycoviruses in mycelium ofPleurotus ostreatus

Double-stranded RNA mycoviruses in mycelium of<i>Pleurotus ostreatus</i>

Double-stranded RNA mycoviruses in mycelium of Pleurotus ostreatus

Mycelium of Pleurotus ostreatus var. florida with a decreased growth rate contained seven double-stranded RNA segments and isometrical virus particles with diameters of 24 and 30 nm. Mycelium with a normal growth rate lacked dsRNA. Protoclones from virus-containing mycelium contained one to seven of these dsRNA segments in varying concentrations. The exact correlation between slow growth and the presence of dsRNA molecules could not be established. Infection of virus-free protoplasts with PEG-precipitated virus particles resulted in mycelium that stably maintained the 2.4 kbp dsRNA.

Hydrolytic properties of extracellular cellulases fromPleurotus ostreatus

Pleurotus ostreatus mycelium produced extracellular cellulases when grown on ground wheat straw. No cellulase activity was detectable when glucose or aqueous extracts of vegetable material were used as substitutes for straw in culture media. The specific activity of excreted cellulases did not vary significantly by increasing the straw concentration from 1 to 6%. Chromatographic fractionation of extracellular proteins gave rise to five fractions with cellulolytic activity. The hydrolytic properties of these partially purified fractions were analysed by using several substrates (carboxymethylcellulose, cellobiose,p-nitrophenyl-β-d-cellobioside,p-nitrophenyl-β-d-lactoside). The results indicate that the cellulase system ofP. ostreatus includes at least a β-glucosidase, two endocellulases, an exoglucohydrolase and an exocellobiohydrolase.

Nuclear abnormality in the mycelia of Pleurotus ostreatus in presence of colchicine

The nuclear abnormality induced by colchicine was examined in Pleurotus ostreatus. The minute nuclei appeared when the mycelial mat was treated with the colchicine solution containing nutrients. The diameter of the minute nuclei was smaller than that of the untreated nuclei. Thus, the minute nuclei were named the ‘smaller nuclei’. They were generated after the appearance of the autopolyploid nuclei, suggesting their generation out of autopolyploid nuclei. The formation of the ‘smaller nuclei’ in the fungus resembled the micronucleation in animal cell.

Effect of staurosporine on growth and hyphal morphology of Pleurotus ostreatus

Staurosporine is a strong inhibitor of protein kinases. At low concentrations, this antibiotic inhibited the growth of both protoplasts and mycelium of Pleurotus ostreatus. Its minimum inhibitory concentrations were 6.5 μM and 9.6 μM for protoplasts and mycelium, respectively. At a lower concentration (0.54 μM), it caused swelling of hyphal tips and subapical regions while some hyphae became stubby and bulbous. The phenomena were compared with the morphological effects of polyoxin D, which is a competitive inhibitor of chitin synthase. The results suggest the involvement of protein kinases(s) in regulation of apical growth of fungi.

Purification and characterization of protein kinase C from Pleurotus ostreatus

Protein kinase C (PKC) from Pleurotus ostreatus mycelium (Basidiomycotina) was purified by affinity chromatography using activated agarose (Affigel 15) coupled with the protein kinase inhibitor N-(2-aminoethyl)-5-isoquinolinesulphonamide hydrochloride. Using buffer containing 2·0 M-arginine. PKC activity eluted as a single peak corresponding to a protein with apparent molecular mass of approximately 68000 Da as estimated by SDS-PAGE. The enzyme was not stimulated by Ca2+ alone, and activation by phosphatidylserine (PS) was significant only at 10−6 M-Ca2+. However, the activity was enhanced by the addition of 1,2-dioctanoyl-sn-glycerol in the presence of PS and Ca2+. Additionally, although sensitivity was lower than for mammalian PKC, the enzyme was activated by a tumour-promoting phorbol ester, phorbol-12-myristate 13-acetate (PMA). The saturation concentration of PMA was 50 g ml−1, which was 5 × 103 times the value for mammalian PKC.

Differently-induced extracellular phenol oxidases from Pleurotus ostreatus

Pleurotus ostreatus mycelium was grown in the presence of tobacco and wheat straw juices, ground wheat straw and acid-precipitable polymeric lignin with the aim of increasing the production of extracellular enzymes potentially implicated in lignin degradation. The highest production of diphenol oxidases was obtained when culture broths were supplemented with solid straw or tobacco juice; cellulase and veratryl alcohol oxidase were produced in detectable amounts in the presence of solid straw and in the absence of any inducer, respectively. No lignin peroxidase was found under any growth condition. Chromatographic fractionation of extracellular proteins and kinetic analysis of partially purified fractions showed that, in the absence of inducers, o-, p- and m-diphenol oxidases could be detected in column eluates, whereas all the inducers tested increased selectively the production of o-diphenol oxidases.

Dearomatization of lignin derivatives by fungal protocatechuate 3,4‐dioxygenase immobilized on porosity glass

Protocatechuate 3,4-dioxygenase (see protocatechuate: oxygen 3,4-oxidoreductase, EC 1.13.11.3) was isolated from the mycelium of Pleurotus ostreatus (induced with p-hydroxybenzoic acid) and immobilized on controlled porosity glass beads. Four fractions of Na-lignosulfonates (varying in M(r), after chromatography on Sephadex G-50) were treated with the immobilized enzyme. The products after incubation showed the same M(r) as the untreated fractions, but their light absorption at 280 nm considerably decreased. These studies indicate that dioxygenase causes partial dearomatization of lignin macromolecule.

Chemical composition of Pleurotus ostreatus mycelial biomass

Mycelium of the edible mushroom Pleurotus ostreatus was cultivated in submerged culture. A glucose-based synthetic medium and a peat extract-based complex medium were employed as nutrient sources in shake-flask fermentations. Mycelial biomass was analysed for total carbohydrates, crude fiber, nitrogen, total lipids, fatty acids, ash, amino acids and mineral composition. The results of the mycelial biomass composition analysis were compared with those of the mushroom fruiting bodies composition analysis. The P. ostreatus mycelium grown in the peat extract-based medium was characterized by a high protein content, a favorable amino acid composition and high concentrations of essential fatty acids and minerals that permit its consideration as a potential food.

Exogenous regulators in the mycelium of Pleurotus ostreatus after exogenous application.

The mycelium of the fungus Pleurotus ostreatus was cultured on a synthetic medium with growth regulators. Best growth was observed on media with 100 ppm IAA, 200 ppm GA3 and 200 ppm of kinetin. Growth of terminal hyphae and the appearance of colonies differed characteristically. Auxin bio-assays showed that the content of substances in younger mycelium slowly increased during cultivation without conspicuous changes in the medium. After exogenous application of IAA the content of auxins in younger mycelium increased and the content of IAA decreased gradually in the culture medium. Gibberellin bio-assays showed their content in the mycelium fell during cultivation and while it increased in the medium. Application of GA3 to the medium leads to a significant increase in these substances in the young mycelium and in the medium their level remains the same. Cytokinin bio-assays showed their content to vary during cultivation. An addition to kinetin to the nutrient medium results in an increase of cytokinins in the mycelium while in the medium the level of cytokinins is maintained. Addition of one substance thus influences the levels of other endogenous regulators.