The microelectrophoretic technique has been used in conjunction with chemical and enzymic treatments to investigate the surface composition of fungal spores. The surface reactions of some cationic fungicides are also considered. Simple carboxyl surfaces, amino-carboxyl surfaces, complex phosphate-containing surfaces, and a surface free of ionogenic material have been identified. The spores of closely related species frequently have widely different surface compositions. Stabilised fungal protoplasts have an amino-carboxyl surface probably derived from protein or lipoprotein. Electrophoretic measurements carried out in the presence of sodium dodecyl sulphate showed lipid to be absent from most of the spores examined. Thin-layer and gas-liquid chromatography showed that lipid on the spore surface differed from lipid extracted from the spore wall. Surface and wall fatty acids had similar major components but the corresponding hydrocarbons differed both quantitatively and qualitatively. A superficial polyphosphate layer on the surface of Penicillium expansum conidia has been demonstrated by microelectrophoresis and confirmed by chemical analysis. The layer is absent from freshly formed spores and its composition is dependent on the phosphate content of the medium. A rodlet layer beneath the polyphosphate is free of cutin and, unlike similar structures on bacterial spores, does not consist of a unique protein. In contrast to the polyphosphate layer the rodlets form an integral part of the wall. A toxic concentration of the surface-active fungicide dodine completely neutralises the charge on protoplasts but has no detectable effect on cell walls. There is no evidence that the toxic reaction is at the spore surface; changes at the protoplast membrane are more likely to be the cause of death.
|Date of Award||1971|