The Effect of Ethidium Bromide Mutagenesis on Dimorphism, Extracellular Metabolism and Cytochrome Levels in Aureobasidium pullulans

Abstract

Treatment of the dimorphic fungus Aureobasidium pullulans with ethidium bromide resulted in the production of several mutants, cultures of which produce an increased proportion of yeast-like cells. A comparison of several mutant isolates with the wild type suggested that the yeast-like cell is responsible for the production of the polysaccharide, pullulan. Mutation was also shown to affect other metabolic patterns, e.g. the reduced accumulation of extracellular ethanol by the mutant. The cytochrome components of the respiratory chain in the wild type were examined by whole-cell spectrophotometry and compared with those of the mutants; the latter had a decreased cytochrome content.