Production of a capsular polysaccharide by a marine filamentous fungus

The spent seawater medium of 4-day-old-cultures of the filamentous marine fungus Leptosphaeria albopunctata had a high viscosity after the fungus was collected by high-speed centrifugation. Microscopic examination of uncentrifuged mycelium suspended in India ink revealed that the viscosity resulted from capsular material. These capsules became disassociated from the mycelium during centrifugation. Precipitation of the medium of centrifuged cultures with 95% ethyl alcohol yielded a highly anthrone-positive polysaccharide material, composed of large amounts of glucose and minute amounts of mannose. Time course studies of the nutritional requirements for capsular polysaccharide production revealed that the capsular material was produced in large amounts, and on a wide variety of sugars, during the period of rapid growth, but was quickly degraded and presumably remetabolized in older cultures. The amount of capsular material produced was enhanced by NaCl concentrations above that of artificial seawater, and KCl could be substituted for NaCl. The salts MgCl(2) and CaCl(2) were also required for capsule production by L. albopunctata, although growth was obtained in cultures without added amounts of these constituents. The possible role of these salts in the metabolism of the fungus is discussed.

Chemical composition of hyphal and sclerotial walls of Sclerotium rolfsii Sacc

The chemical components of the sclerotial and hyphal walls of the fungus Sclerotium rolfsii Sacc. are compared. Sclerotial walls contain a melanin-like pigment which is absent from hyphal walls. They are also higher in non-hydro-lyzable residue, in lipids, and in ash content. In both walls, glucose, mannose, and glucosamine are found after acid hydrolysis. Acid hydrolysates of sclerotial and hyphal walls contain 10 and 13 amino acids, respectively, L-arginine, L-serine, and L-proline being absent from sclerotial walls. The possible role of some of these components in the resistance of the sclerotia to biological and chemical degradation is discussed.

Hyphal cell wall structure of two species of Pythium

Hyphal cell walls were prepared by ultrasonication. Glucose was the only sugar detected in both species. Evidence was obtained indicating that the Pythium butleri Subram. glucan is beta 1,2-linked, and that the glucan of Pythium myriotylum Drechsler is beta 1,4-linked. Sixteen amino acids were detected in P. butleri cell wall hydrolysates. Four of these amino acids were absent from P. myriotylum preparations. Similar quantities of lipid were found in both species. The significance of these data for fungal classification is discussed.

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