J. S. D. Bacon

Comparison of ultrastructure and chemical components of cell walls of certain plant pathogenic fungi

Hyphal walls and, where possible, sclerotial walls of the plant pathogenic fungi Sclerotium cepivorum, S. rolfsii, S. tuliparum, Sclerotinia narcissicola, S.fructigena and Rhizoctonia solani have been examined by electron-microscope techniques and analytical methods, including X-ray diffraction, infrared absorption spectroscopy and paper chromatography. Infrared data, sugar analysis of hydrolysates and lytic experiments indicate that the composition of the walls of S. tuliparum differs markedly from that of other species of Sclerotium but is similar to Rhizoctonia. The other Sclerotium species are similar in wall composition to the species of Sclerotinia investigated.

A study of the microbial lysis of the cell walls of soil yeasts (Cryptococcus spp.)

Abstract The difference in the ability of lytic microorganisms to bring about dissolution of the cell walls of the soil yeasts Cryptococcus albidus and C. terreus has been examined. It was found that the composition of the cell walls, which varied according to the cultural conditions employed, determined the extent to which the walls were lysed. Thus walls from cells of C. albidus grown under conditions favourable for growth contained α- and β-glucans and chitin as major components and were lysed by two Streptomyces spp. but not by a nonfruiting myxobacterium Cytophaga johnsonii . Significant lysis of C. albidus walls by the myxobacterium as well as by the Streptomyces sp. occurred, however, when the α-glucan component was considerably reduced by growing the yeast under unfavourable conditions. Ultrastructural studies showed the absence of definite layers in the wall. The chitinous residue after chemical extraction of the walls retained the general shape of the cell and was composed of microfibrils, in contrast to the granular chitinous residues from other yeasts e.g. Saccharomyces spp.