Morphological, cytological and genetic analyzes of the 'sango' mutant with the defects in basidiocarp development in edible mushroom Pleurotus pulmonarius.

A spontaneous, morphological variation 'sango' was observed in the progeny of a Pleurotus pulmonarius (Fr.) Quél. wild-type basidiocarp (also known as fruiting body) collected from the field. This variant developed wart- and coral-like structures instead of normal basidiocarps. Microscopic analysis showed that the sango phenotype had defects in the differentiation of the pileus and hymenium. Basidiocarp phenotypic data analysis in the progenies revealed that the sango trait is a heritable mutation character controlled by a single recessive gene. This mutation locus was mapped on linkage group III of a previously constructed genetic linkage map by amplified fragment length polymorphism (AFLP) technique in P. pulmonarius. Four AFLP markers identified by bulked segregant analysis showed linkage to the sango mutation locus, with the genetic distance ranging from 0 to 2.1 cM. Of these markers, one marker was co-segregated with the sango mutation locus. This knowledge will be a useful foundation for practical breeding as well as for elucidating molecular mechanisms in basidiocarp development of main edible mushrooms.

Advanced Materials From Fungal Mycelium: Fabrication and Tuning of Physical Properties.

In this work is presented a new category of self-growing, fibrous, natural composite materials with controlled physical properties that can be produced in large quantities and over wide areas, based on mycelium, the main body of fungi. Mycelia from two types of edible, medicinal fungi, Ganoderma lucidum and Pleurotus ostreatus, have been carefully cultivated, being fed by two bio-substrates: cellulose and cellulose/potato-dextrose, the second being easier to digest by mycelium due to presence of simple sugars in its composition. After specific growing times the mycelia have been processed in order to cease their growth. Depending on their feeding substrate, the final fibrous structures showed different relative concentrations in polysaccharides, lipids, proteins and chitin. Such differences are reflected as alterations in morphology and mechanical properties. The materials grown on cellulose contained more chitin and showed higher Young's modulus and lower elongation than those grown on dextrose-containing substrates, indicating that the mycelium materials get stiffer when their feeding substrate is harder to digest. All the developed fibrous materials were hydrophobic with water contact angles higher than 120°. The possibility of tailoring mycelium materials' properties by properly choosing their nutrient substrates paves the way for their use in various scale applications.

Production of mycelial biomass by the Amazonian edible mushroom Pleurotus albidus

ABSTRACT Edible mushroom species are considered as an adequate source of food in a healthy diet due to high content of protein, fiber, vitamins, and a variety of minerals. The representatives of Pleurotus genus are characterized by distinct gastronomic, nutritional, and medicinal properties among the edible mushrooms commercialized worldwide. In the present study, the growth of mycelial biomass of Pleurotus albidus cultivated in submerged fermentation was evaluated. Saccharose, fructose, and maltose were the three main carbon sources for mycelial biomass formation with corresponding yields of 7.28 g L−1, 7.07 g L−1, and 6.99 g L−1. Inorganic nitrogen sources did not stimulate growth and the optimal yield was significantly higher with yeast extract (7.98 g L−1). The factorial design used to evaluate the influence of saccharose and yeast extract concentration, agitation speed, and initial pH indicated that all variables significantly influenced the production of biomass, especially the concentration of saccharose. The greater amount of saccharose resulted in the production of significantly more biomass. The highest mycelial biomass production (9.81 g L−1) was reached in the medium formulated with 30.0 g L−1 saccharose, 2.5 g L−1 yeast extract, pH 7.0, and a speed of agitation at 180 rpm. Furthermore, P. albidus manifested different aspects of morphology and physiology under the growth conditions employed. Media composition affected mycelial biomass production indicating that the diversification of carbon sources promoted its improvement and can be used as food or supplement.

Production of mycelial biomass by the Amazonian edible mushroom Pleurotus albidus.

Edible mushroom species are considered as an adequate source of food in a healthy diet due to high content of protein, fiber, vitamins, and a variety of minerals. The representatives of Pleurotus genus are characterized by distinct gastronomic, nutritional, and medicinal properties among the edible mushrooms commercialized worldwide. In the present study, the growth of mycelial biomass of Pleurotus albidus cultivated in submerged fermentation was evaluated. Saccharose, fructose, and maltose were the three main carbon sources for mycelial biomass formation with corresponding yields of 7.28gL(-1), 7.07gL(-1), and 6.99gL(-1). Inorganic nitrogen sources did not stimulate growth and the optimal yield was significantly higher with yeast extract (7.98gL(-1)). The factorial design used to evaluate the influence of saccharose and yeast extract concentration, agitation speed, and initial pH indicated that all variables significantly influenced the production of biomass, especially the concentration of saccharose. The greater amount of saccharose resulted in the production of significantly more biomass. The highest mycelial biomass production (9.81gL(-1)) was reached in the medium formulated with 30.0gL(-1) saccharose, 2.5gL(-1) yeast extract, pH 7.0, and a speed of agitation at 180rpm. Furthermore, P. albidus manifested different aspects of morphology and physiology under the growth conditions employed. Media composition affected mycelial biomass production indicating that the diversification of carbon sources promoted its improvement and can be used as food or supplement.

Characterization of the wzc gene from Pantoea sp. strain PPE7 and its influence on extracellular polysaccharide production and virulence on Pleurotus eryngii.

To characterize of the pathogenicity gene from the soft rot pathogen Pantoea sp. PPE7 in Pleurotus eryngii, we constructed over 10,000 kanamycin-resistant transposon mutants of Pantoea sp. strain PPE7 by transposon mutagenesis. One mutant, Pantoea sp. NPPE9535, did not cause a soft rot disease on Pleurotus eryngii was confirmed by the pathogenicity test. The transposon was inserted into the wzc gene and the disruption of the wzc gene resulted in the reduction of polysaccharide production and abolished the virulence of Pantoea sp. strain PPE7 in P. eryngii. Analysis of the hydropathic profile of this protein indicated that it is composed of two main domains: an N-terminal domain including two transmembrane α-helices and a C-terminal cytoplasmic domain consisting of a tyrosine-rich region. Comparative analysis indicated that the amino acid sequence of Wzc is similar to that of a number of proteins involved in the synthesis or export of polysaccharides in other bacterial species. Purified GST-Wzc was found to affect the phosphorylation of tyrosine residue in vivo. These results showed that the wzc gene might play an important role in the virulence of Pantoea sp. strain PPE7 in P. eryngii.

Abiotic and biotic degradation of oxo-biodegradable plastic bags by Pleurotus ostreatus.

In this study, we evaluated the growth of Pleurotus ostreatus PLO6 using oxo-biodegradable plastics as a carbon and energy source. Oxo-biodegradable polymers contain pro-oxidants that accelerate their physical and biological degradation. These polymers were developed to decrease the accumulation of plastic waste in landfills. To study the degradation of the plastic polymers, oxo-biodegradable plastic bags were exposed to sunlight for up to 120 days, and fragments of these bags were used as substrates for P. ostreatus. We observed that physical treatment alone was not sufficient to initiate degradation. Instead, mechanical modifications and reduced titanium oxide (TiO2) concentrations caused by sunlight exposure triggered microbial degradation. The low specificity of lignocellulolytic enzymes and presence of endomycotic nitrogen-fixing microorganisms were also contributing factors in this process.

Pleurotus ostreatus biofilms exhibit higher tolerance to toxicants than free-floating counterparts.

The MBEC(TM)-High Throughput Assay based on the Calgary Biofilm Device was used to produce and to characterize Pleurotus ostreatus biofilms. Hydroxyapatite coating of pegs was required to enable biofilm attachment; biofilm amounts and homogeneity of distribution were markedly improved upon removal of non-sessile biomass after 48 h from inoculation. Scanning electron microscopy showed surface-associated and multi-layered growth stabilized by the presence of an extracellular matrix (ECM). Biofilms had higher contents of total sugars and ECM than their free-floating counterparts. Tolerance to Cr(VI) in the former was about twice that of the latter as inferred by the respective inhibitory concentrations (48.4 vs 24.1 mM and 114.5 vs 61.0 mM in 4- and 7-d-old cultures, respectively). Biofilms also displayed superior olive-mill wastewater (OMW) treatment efficiency along 5 consecutive batches leading to chemical oxygen demand and total phenol removals higher than 50 and 90%, respectively. Laccase activity peaks in biofilm cultures grown on OMW were significantly higher than those in free-floating cultures.

Pleurotus ostreatus biofilm-forming ability and ultrastructure are significantly influenced by growth medium and support type.

AIMS: To investigate the effect of support and growth medium (GM) on Pleurotus ostreatus biofilm production, specific metabolic activity (SMA) and ultrastructure. METHODS AND RESULTS: Biofilms were developed on membranes covering a broad range of surface properties and, due to the applicative implications of mixed biofilms, on standard bacterial GM in stationary and shaken culture. Hydrophilic (glass fibre, Duran glass and hydroxyapatite) and mild hydrophobic (polyurethane, stainless steel, polycarbonate, nylon) supports were more adequate for biofilm attachment than the hydrophobic Teflon. Among the GM, sucrose-asparagine (SA) was more conducive to biofilm production than Luria-Bertani and M9. GM was more influential than support type on biofilm ultrastructure, and a high compactness was evident in biofilms developed on SA. Biofilms on Duran glass were more efficient than planktonic cultures in olive-mill wastewater treatment. CONCLUSIONS: The main effects of support and GM variables and their binary interactions on both biofilm production and SMA were all highly significant (P < 0·001): thus, the magnitude of the effect of each variable strongly depended on the level of the other one. SIGNIFICANCE AND IMPACT OF THE STUDY: There is a lack of basic information regarding physiology and ultrastructure of P. ostreatus biofilms. To our knowledge, this is the first attempt to fill this gap, thus representing a basis for future studies.

Microscopia de epifluorescência para a determinação de biomassa micelial em substrato de cultivo sólido particulado / Epifluorescense microscopy for the determination of mycelial biomass in particulated solid substrate cultivation / Microscopia de pifluorescencia para la determinación de biomasa micelial en sustrato de cultivo solido particulado

A determinação de biomassa micelial fúngica crescida em substratos de cultivo sólido particulado (SCSP) é ainda um desafio devido à dificuldade de separação do micélio e o substrato. O objetivo deste trabalho foi avaliar a técnica de microscopia de epifluorescência para determinação da biomassa micelial de Pleurotus ostreatus em SCSP. Para determinação da exatidão da metodologia P. ostreatus foi crescido em meio líquido de extrato de malte e; a biomassa micelial foi separada por centrifugação, liofilizada e moída. Concentrações conhecidas do pó do micélio foram misturadas ao SCSP, composto de bagaço de cana de açúcar e fibra de soja, previamente autoclavado. Em seguida, a biomassa micelial foi determinada por microscopia de epifluorescência. Para promover a variação da biomassa micelial a ser determinada por microscopia de epifluorescência, SCSP adicionado de diferentes concentrações de ferro foram utilizados para o crescimento do fungo. Concluiu- -se que a técnica apresenta baixa precisão e exatidão, o que implica na necessidade de maiores estudos para aplicação desta técnica para a determinação de biomassa micelial crescida em SCSP.

Determination of fungal mycelial biomass grown on solid substrate cultivation (SSC) is still a challenge due to the difficulty in separating mycelium and substrate. The objective of this study was to evaluate the epifluorescence microscopy to determine the mycelial biomass of Pleurotus ostreatus grown in SSC. P. ostreatus was grown in malt extract liquid medium and mycelial biomass was separated by centrifugation. It was then lyophilized and milled. Mycelial powder was added at known concentrations to SSC composed of sugarcane bagasse and soy fiber, previously autoclaved. Mycelial biomass was determined by epifluorescence microscopy. In order to promote mycelial biomass variation for the determination by epifluorescence microscopy, SSC added at different iron concentrations was used for fungus growth. It was concluded that the technique has low precision and accuracy, which implies the need for further studies in order to apply this technique for the determination of mycelial biomass grown in SSC.

La determinación de biomasa micelial fúngica crecida en sustratos de cultivo sólido particulado (SCSP) es todavía un reto debido a la dificultad de separación del micelio y el sustrato. El objetivo de este estudio fue evaluar la técnica de microscopía de epifluorescencia para determinación de la biomasa micelial de Pleurotus ostreatus en SCSP. Para determinación de exactitud de la metodología P. ostreatus se cultivó en medio líquido de extracto de malta y; la biomasa micelial separada por centrifugación, liofilizada y molida. Concentraciones conocidas del polvo del micelio fueron mezcladas al SCSP, compuesto de bagazo de caña de azúcar y fibra de soya, previamente tratado en autoclave. A continuación, la biomasa micelial a ser determinada por microscopía de epifluorescencia. Para promover la variación de la biomasa micelial a ser determinada por microscopía de epifluorescencia, SCSP añadida con diferentes concentraciones de hierro fueron utilizados para el crecimiento del hongo. Se concluye que la técnica presenta baja precisión y exactitud, lo que implica en la necesidad de realizar más estudios para aplicación de esta técnica para la determinación de biomasa micelial crecida en SCSP.

Produção de lacase de fungos basidiomicetos por fermentação submersa com cascas de café / Laccase production from basidiomycetes by submerged fermentation with coffee hurks / Producción de lacase de hongos basidiomicetos por fermentación sumergida con cascaras de café

Cascas de café são fonte de carboidratos e nutrientes que podem ser bioconvertidos em produtos de interesse como enzimas. Lacases são cobre polifenol oxidases que oxidam compostos fenólicos, enquanto reduzem oxigênio molecular à água e; sua baixa especificidade a substratos permite sua aplicação em várias áreas como indústria têxtil, de alimentos e biorremediação. Os objetivos desse trabalho foram avaliar a capacidade de produção de lacase de três linhagens de fungos basidiomicetos (Lentinula edodes U6/1, Pleurotus ostreatus U6/9 e Pleurotus florida U6/10) por fermentação submersa com cascas de café e avaliar o uso de cobre como indutor dessa enzima. A casca de café mostrou ser um bom substrato para produção de lacases e das três linhagens testadas Pleurotus ostreatus (U6/9) foi a mais produtiva (22,5 U mL-1). A melhor fonte de nitrogênio para produção de lacases de Pleurotus ostreatus (U6/9) foi o extrato de levedura na concentração de 9 g/L (20 U mL-1). A adição de 150 μM de CuSO4 resultou na indução significativa na produção de lacases nessa linhagem (21 U mL-1) no 12° dia de cultivo.

Coffee husks are a source of carbohydrates and nutrients that may be bioconverted into products of interest, such as enzymes. Laccases are copper polyphenol oxidases that oxidize phenolic compounds while reducing molecular oxygen to water. Laccase’s low specificity to substrates allows its application in several areas such as textiles, food processing and bioremediation industries. The aims of this study were to evaluate the potential to produce laccase from three strains of basidiomycetous fungi (Lentinula edodes U6/1, Pleurotus ostreatus U6/9, and Pleurotus florida U6/10) by submerged fermentation with coffee husks, and to evaluate the use of copper as an inducer of the enzyme. Coffee husk proved to be a good substrate for laccase production, with Pleurotus ostreatus (U6/9) being the most productive strain (22.5 U mL-1). The best source of nitrogen for laccase production of Pleurotus ostreatus (U6/9) was yeast extract 9 g/L (20 U mL-1). The addition of CuSO4 (150 μM) resulted in significant induction of laccase (21 U mL-1) on the 12th day of cultivation.

Cáscaras de café son fuente de carbohidratos y nutrientes que pueden ser bioconvertidos en productos de interés, tales como enzimas. Lacases son cobre polifenol oxidasas que oxidan compuestos fenólicos, mientras reducen el oxígeno molecular a el agua y; su baja especificidad a sustratos permite su aplicación en diversas áreas, como la industria textil, de alimentos y de biorremediación. Los objetivos de este estudio fueron evaluar la capacidad de producción de lacase de tres linajes de hongos basidiomicetos (Lentinula edodes U6/1, Pleurotus ostreatus U6/9 y Pleurotus florida U6/10) por fermentación sumergida con cáscaras de café, y evaluar el uso del cobre como inductor de esta enzima. La cáscara de café resultó ser un buen sustrato para la producción de lacases y, de las tres linajes probadas, Pleurotus ostreatus (U6/9) fue la más productiva (22,5 U mL-1). La mejor fuente de nitrógeno para la producción de lacases de Pleurotus ostreatus (U6/9) fue el extracto de levadura a una concentración de 9 g L-1 (20 U mL-1). La adición de 150 μM de CuSO4 resultó en la inducción significativa de Cáscaras de café son fuente de carbohidratos y nutrientes que pueden ser bioconvertidos en productos de interés, evadura a una concentración de 9 g L-1 (20 U mL-1). La adición de 150 μM de CuSO4 resultó en la inducción significativa de la producción de lacases en esa linaje (21 U mL-1), en el 12º día de cultivo.

Influence of calcium and silicon supplementation into Pleurotus ostreatus substrates on quality of fresh and canned mushrooms.

Supplements of gypsum (calcium source), pumice (silicon source) and pumice sulfate (silicon and calcium source) into substrates for oyster mushrooms (Pleurotus ostreatus) were searched for their effects on production as well as qualities of fresh and canned mushrooms. The addition of pumice up to 30% had no effect on total yield, size distribution and cap diameters. The supplementation of gypsum at 10% decreased the total yield; and although gypsum at 5% did not affect total yield, the treatment increased the proportion of large-sized caps. High content (>10%) of pumice sulfate resulted in the lower yield. Calcium and silicon contents in the fruit bodies were not influenced by supplementations. The centrifugal drip loss values and solid content of fresh mushrooms, and the percentage of weight gained and firmness of canned mushrooms, cultivated in substrates supplemented with gypsum, pumice and pumice sulfate were significantly (p≤0.05) higher than those of the control. Scanning electron micrographs revealed the more compacted hyphae of mushroom stalks supplemented with silicon and/or calcium after heat treatment, compared to the control. Supplementation of P. ostreatus substrates with 20% pumice was the most practical treatment because it showed no effect on yield and the most cost-effective.

Investigation of growth responses in saprophytic fungi to charred biomass.

We present the results of a study testing the response of two saprophytic white-rot fungi species, Pleurotus pulmonarius and Coriolus versicolor, to charred biomass (charcoal) as a growth substrate. We used a combination of optical microscopy, scanning electron microscopy, elemental abundance measurements, and isotope ratio mass spectrometry ((13)C and (15)N) to investigate fungal colonisation of control and incubated samples of Scots Pine (Pinus sylvestris) wood, and charcoal from the same species produced at 300 degrees C and 400 degrees C. Both species of fungi colonise the surface and interior of wood and charcoals over time periods of less than 70 days; however, distinctly different growth forms are evident between the exterior and interior of the charcoal substrate, with hyphal penetration concentrated along lines of structural weakness. Although the fungi were able to degrade and metabolise the pine wood, charcoal does not form a readily available source of fungal nutrients at least for these species under the conditions used in this study.

[Morphogenesis and ultrastructure of basidiomycetes Agaricus and Pleurotus mitochondria].

Mitochondrial morphogenesis in 31 strains of 9 species of Agaricus--A. arvensis Schaeff., A. bisporus (Lange) Imbach, A. bitorquis (Quel.) Sacc., A. campestris L., A. excellens (F. H. Moller) F. H. Moller, A. macrocarpus (F. H. Möller) F. H. Möller, A. silvaticus Schaeff., A. silvicola (Vittad.) Peck, A. xanthodermus Genev--and 2 strains of Pleurotus--P. ostreatus (Jacg.) P. Kumm., P. pulmonarius (Fr.) Quel.--has many common features in mitochondria distribution under favorable growth conditions (type 1) and in reconstruction of chondriom (fission or fragmentation) under unfavorable growth conditions and aging (type 2). The first type of mitochondria distribution was observed in heterokaryotic mycelium of some Agaricus strains and Pleurotus grown in agar medium during 7-14 days, and also in submerged mycelium of some Agaricus strains and Pleurotus. The second type of mitochondria distribution was observed in homokaryotic Agaricus strains under condition of starvation, in aging mycelium (28 days of growth), and in submerged mycelium of most of Agaricus strains. The first type of chondriom consists of small granular mitochondria in the apical cells and long snake-like network in subapical cells, and restores almost completely the mitochondrial network in the aging mycelium cells. The second type of chondriom consists of small granular mitochondria in all cells of mycelium. The surface of chondriom type 2 mitochondrial membrane was usually closely associated with ribosomes and changed crists. Such mycelium cells in A. bisporus strain Bs94 were TUNEL positive. So, the types of mitochondria morphogenesis in the Agaricus and Pleurotus mycelium cells are similar at different time and growth conditions and depend on complex of physiological and biochemical process in the mycelium cells.

Accumulation and localization of cesium in edible mushroom (Pleurotus ostreatus) mycelia.

The characteristics of Cs accumulation and localization in edible mushrooms were examined using the mycelia of Pleurotus ostreatus-Y1. Scanning electron microscope images revealed the existence of white spots, and energy dispersive X-ray microanalyzer analysis indicated the presence of larger amounts of Cs and P in these spots in mycelia cultured on medium containing 25 mM CsCl. The (137)Cs activities in the mycelia were approximately 4-6 times higher than those in water used for (137)Cs elution. Higher Cs concentrations in the sediment fraction including vacuolar pellets were obtained compared to the upper fractions. It was observed that yellowish spots caused by the fluorescence of 4',6-diamidino-2-phenylindole (DAPI)-stained polyphosphate were localized in the mycelia. The higher fluorescence intensity of the yellowish-grained spots was measured in comparison with other regions in the mycelium. These results suggested that Cs in the mycelia was trapped by polyphosphate in vacuoles or other organelles.

Microscopic observations of the early development of Pleurotus pulmonarius fruit bodies.

From observations made by light microscopy, transmission electron microscopy, environmental-scanning and cryoscanning electron microscopy we conclude that the expansion of the young fruit body of Pleurotus pulmonarius involves considerable vacuolation of hyphae but no marked inflation of cell dimensions. There is evidence for an extensive extracellular matrix (ECM), the components of which must be under the control of the hyphae which the ECM surrounds. However the ECM in these fruit bodies is a dilute material. It is easily lost during specimen preparation and is evident only when certain techniques are used to preserve the fluid surface of the hyphae. Observations of the hyphal and fruit body structures with a range of conventional microscopic techniques are crucial to complement the information obtained through physiological and molecular studies for understanding the cellular changes that occur during mushroom development.

[Comparative analysis of Pleurotus ostreatus natural isolates].

A comparative analysis is performed of the polymorphism of the Pleurotus ostreatus (Fr.) Kumm naturally occurring strains isolated from the natural substrates found in two geographically remote Russian natural preserves, the Central Arboreal Biosphere Tver State Preserve (CABTSP) and the Moscow State University Zvenigorod Biological Station (ZBS, Moscow oblast), and within the city of Moscow. The results of the frequency analysis for the isozyme loci alleles and for the sexual and vegetative incompatibility groups are presented; the genetic structure and the interpopulation relations among 58 P. ostreatus dikaryotic strains are estimated. The natural samples from the Moscow and Tver oblasts are shown to have a high degree of polymorphism with a genetic differentiation of 0.743; in spite of their territorial remoteness, they are, however, actively exchanging genetic material. The natural fungal isolates form two reproductively isolated groups.

[Ultrastructure of the cell wall in vegetative mycelia of Agaricus bisporus (Lange) Imbach]. / Osobennosti ul'trastruktury kletochnoi stenki vegetativnogo mitseliia Agaricus bisporus (Lange) Imbach.

A comparative description of the cell wall ultrastructure was made for vegetative mycelia in Agaricus bisporus, other species of Agaricus, and Pleurotus ostreatus. Apart from well known ultrastructural features of cell walls of the examined strains, inclusions of different kinds were observed. The cell wall thickness varied in different Agaricus strains. Maximum differences between the examined strains were 1.4 times. The cell wall thickness in P. ostreatus strains was by 3 to 4 times less than that in Agaricus strains. Using electron micrographs, a brief description of mycelia and A. bisporus basidia ultrastructure was composed.

Simple staining detects ultrastructural and biochemical differentiation of vegetative hyphae and fruit body initials in colonies of Pleurotus pulmonarius.

AIMS: To know the ultrastructural and biochemical differences of vegetative hyphae and fruit body initials in colonies of Pleurotus pulmonarius. METHODS AND RESULTS: Feulgen reagent was used to detects differentiation of hyphae. The intracellular laccases, proteases and beta-1,3-glucanases activity, content of cytoplasmic protein, glycogen and glucans in the cell wall were evaluated in hyphae of fruit body initials and in vegetative hyphae. The thickness of hyphal walls of the vegetative hyphae was also evaluated. Substantial biochemical changes were observed in hyphae of different zones of the fruiting colony. Hyphae at the periphery had thinner walls than in the centre of the colony. CONCLUSION, SIGNIFICANCE AND IMPACT OF THE STUDY: Staining correlated with the enzymatic activity, protein, glycogen and glucans, in mycelium and in fruit body initials. The implications are that hyphal maturity in P. pulmonarius involves storage of glucans, in part at least, in the form of a thickened hyphal wall.

Influence of the substrate on the ultrastructure of Pleurotus pulmonarius fruit body primordia.

Pleurotus pulmonarius fruit body primordia (FBP) formed on potato extract agar (PEA) and wheat straw-based media (WS) were studied. When grown on PEA, FBP hyphae had a large number of vacuoles and less stainable cytoplasmic material. In contrast, when grown on WS, there was abundant cytoplasmic material and fewer vacuoles. FBP grown on WS had a more well-defined mushroom shape than those grown on PEA. The average hyphal diameters on PEA and WS were 4.15 and 3.52 micro m, respectively; the average hyphal lengths were 11.75 and 11.80 micro m, respectively. The control mechanisms regulating formation of the normal shape and size of FBP might be more dependent on the amount of cytoplasmic material than on the physical volume of the hyphal compartment. Since the ultrastructure of the hyphal compartment, which makes up the substance of the FBP, depends on the substrate in which the FBP has been grown, the composition of the substrate may be important for manipulating the nutritive and organoleptic characteristics of the mushroom crop.