Polysaccharide composition of mycelium and cell walls of the fungus Penicillium roqueforti

Preliminary data on the polysaccharide composition of mycelium and cell walls of the submergedly grown fungus Penicillium roqueforti were obtained. Mild acid hydrolysis of mycelium and cell walls led to formation of glucose, mannose and galactose, whereas acid treatment under drastic conditions afforded glucosamine as the hydrolysis product of chitin, which content in the cell walls was estimated as 19%. Sequential treatment of the mycelium with hot water and 1 M NaOH at room temperature gave rise to several polysaccharide fractions, which were characterized by their monosaccharide composition. The main fraction obtained by the action of alkali, according to NMR spectroscopy, mass spectrometry and chemical methods of structural analysis data, is a linear alpha-D-glucopyranan containing blocks of (1 --> 3)-linked glucose residues interconnected by (1 --> 4)-linkages. Water-soluble polysaccharides contained linear blocks of (1 --> 5)-linked beta-galactofuranose residues, probably connected with a mannan core. The data obtained may be important for chemotaxonomy of the genus Penicillium.     

Colloidal crystal-like structure of sporopollenin in the megaspore walls of Recent Selaginella and similar fossil spores

HEMSLEY, A. R., COLLINSON, M. E. & BRAIN, A. P. R., 1992. Colloidal crystal-like structure of sporopollenin in the megaspore walls of Recent Selaginella and similar fossil spores. TEM and SEM studies of iridescent fossil Erlansonisporites and Recent Selaginella spores reveal a wall composed of three regions. The central region consists of close-packed particles in a semi-crystalline arrangement. This organization is compared with that of aggregated Iridoviridae, prolamellar bodies, lipid micelles and precious opal. Our observations suggest that the structure of this wall region (and that of the remaining regions) can be explained by derivation from colloidal mixtures. It is concluded that colloids and their precursors may play a far more significant part in spore and pollen wall structure than was previously believed.     

Some comments on the aerobiology of fungus spores

While exposure/symptom relationships are relatively well-defined for pollen allergens, such relationships have not been clearly established for airborne fungus spores due to a lack of clearly defined seasonal patterns, prevalence of world-wide cosmopolitan fungi, and serious problems with sampling and identification. Ascospores and basidiospores have been least studied with respect to aerobiology, although both are clearly allergenic. Preliminary data on allergenicity and diurnal and seasonal prevalence patterns for selected ascospore and basidiospore types are presented.     

The surface structure of saprophytic and parasitic dermatophyte spores

The surface structure of conidia and arthrospores ofMicrosporon ²)racemosum andTrichophyton winacei is described. Apart fromMicrosporon macroconidia, the spore surfaces displayed little or no ornamentation. The arrangement of verrucae on the surface ofMicrosporon conidia appears to be variable, but may be of little taxonomic importance other than as a characteristic of the genus.

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Zusammenfassung Die Oberflächenstruktur der Konidien und Arthrosporen vonMicrosporon racemosum undTrichophyton erinacei sind beschrieben. Abgesehen von den Makrokonidien vonMicrosporon zeigten die Oberflächen der Sporen geringe oder keine Ornamentation. Die Anordnung der Warzen an der Oberfläche von Makrosporenkonidien erscheint wechselvoll und sie mag von geringer Wichtigkelt sein, außer der Charakterisierung der Gattung.

     

The effect of sunlight on allergen release from spores of the fungus Alternaria

Airborne fungal spores are known carriers of allergen. Correlations between spore counts and allergen concentrations are poor. It is known that germination increases allergen release, implicating spore viability as a determinant of allergen release. During aerial dispersal, spores can be exposed to prolonged periods of ultraviolet (UV) light which can reduce viability of spores. We examined the relation between spore viability and allergen release in two experiments: firstly spores from culture were treated with a UV wavelength of 254?nm (not present in sunlight reaching the earth's surface) or autoclaved, and secondly, spores were exposed to simulated sunlight over three days. In both studies viability was measured (by germination on agar and by metabolic activity with nitro-blue tetrazolium vital stain) and allergen release by the Halogen immunoassay. The UV light reduced the proportion of spores able to germinate but did not affect metabolic activity or allergen release. Autoclaving reduced the proportion of spores releasing allergen by half (p<0.0001). Three days' exposure to simulated sunlight correlated negatively with spore germination and metabolic activity (p<0.0001), but did not affect allergen release (p=0.799). In conclusion, simulated sunlight reduced the metabolic activity and germinability of spores however the proportion releasing allergen remained unaffected. These findings suggest that spore counts may reflect allergen concentrations in the air if spores are dead or dormant. The contribution of viable spores to concentrations of airborne allergen, as well as the role of germination in allergen delivery to the respiratory tract, remains to be resolved.     

The fine structure of frozen-etched bacillus cereus spores

Summary The fine structure of Bacillus cereus spores was studied using the freeze-etching technique and compared with that already described in chemically fixed cells. Although the basic structures did not appear different, the freeze-etching technique permitted the examination of membrane surfaces and their involvement in sporulation. In this respect, some membranes were found to be covered with small 120 Å particles believed to represent multi-enzyme complexes, while other membranes appeared relatively smooth.One feature revealed by the freeze-etching technique and not demonstrated in chemically fixed cells, was the presence of relatively large (500 Å) vesicular structures. In many instances these vesicles were closely associated with different layers or membranes in the developing spore. While the role of these vesicular structures is as yet undetermined, their possible connection with the lytic process which liberates the spore from the sporangium, is discussed.     

Relation of the heat resistance of bacterial spores to chemical composition and structure II. Relation to cortex and structure

The relation between the amount of cortex, measured as total hexosamine, as diaminopimelic acid and as muramic lactam, and the heat resistance of spores of five different strains of Bacillus stearothermophilus was studied. Electron micrographs of thin sections of the spores were made to relate the structure of the spores to chemical and thermal characteristics. It was found that the amount of the cortex was significantly related to heat resistance of the spores. Strains with more electron-dense and better organized cortices were found to express higher heat resistance.     

The cell walls of Pseudomonas aeruginosa. General composition

1. Cell walls of Pseudomonas aeruginosa were prepared and analysed. 2. Separate preparations were found to be reproducible, e.g. the phosphorus contents of all batches lay in the range 2.0-2.1%. 3. Ninhydrin-positive compounds in hydrolysates accounted for 43-46% of the cell wall and 79-87% of the nitrogen of the cell wall. Examination of the results for individual ninhydrin-positive compounds showed that 5-15% of the cell wall was murein and about 30% protein. 4. Trypsin treatment of crude cell-wall preparations preferentially liberated arginine, lysine and leucine, but it was not clear whether these arose from cell-wall or cytoplasmic proteins.     

Splash dispersal of fungus spores and fungicides in the laboratory and greenhouse

A laboratory technique is described for the production of drops of simulated rain in which fungal spores were suspended. When such drops containing conidia of Botrytis fabae impacted on a target leaf the secondary droplets produced infections on receptor broad bean leaves. The capacity of fungicides applied to the target leaf to redistribute in secondary splash droplets was examined in terms of the infectivity of the spores in the droplets. The extent to which a copper fungicide reduced infection on the receptor leaves was related to the level and tenacity of the fungicide deposit on the target leaf. The effect of wetting agents on the redistribution of this fungicide could probably be explained by their influence on the tenacity of the initial deposit. In general the capacity of different fungicides to inhibit infection by the secondary droplets was related to the inherent toxicity of the fungicides to B. fabae. Implications of the dispersal of spores and fungicides by rain splash are briefly considered with reference to field conditions.     

Relation of the heat resistance of bacterial spores to chemical composition and structure. II. Relation to cortex and structure

The relation between the amount of cortex, measured as total hexosamine, as diaminopimelic acid and as muramic lactam, and the heat resistance of spores of five different strains of Bacillus stearothermophilus was studied. Electron micrographs of thin sections of the spores were made to relate the structure of the spores to chemical and thermal characteristics. It was found that the amount of the cortex was significantly related to heat resistance of the spores. Strains with more electron-dense and better organized cortices were found to express higher heat resistance.