Abstract
To clarify the mode of action of erythromycin on eucaryotic cells, the morphological and biochemical changes of Cochliobolus miyabeanus with erythromycin were studied and following results were obtained. (1) The potato-sucrose medium containing 2000 μg/ml of erythromycin showed 50% inhibition of this fungal growth. (2) The mycelium grown in the presence of erythromycin (2000 μg/ml) was fixed in 2% KMnO4, dehydrated by the usual method, and subjected to scanning electron microscopic observation (Hitachi SSM-II). Most of these mycelia showed morphological changes and looked like the beans of a rosary, whereas thiamphenicol and cycloheximide, which are inhibitors of protein synthesis like erythromycin, did not cause the same morphological changes. (3) Analysis of mycelia of the fractionated into soluble carbohydrate, nucleic acid, lipid, and chitin-like subsatnce showed very little differences between the mycelia grown in the presence and absence of erythromycin. (4) The enzyme activities concerned in the synthesis or decomposition of cell-wall main components (β-glucan and chitin-like substance) were not affected by the addition of erythromycin while a little inhibition of proteolytic enzyme activities was seen by the presence of erythromycin.
