Elevated polysaccharide production by mutants of the fungus Aureobasidium pullulans

Abstract Two mutants of the fungus Aureobasidium pullulans ATCC 42023 were isolated that exhibited elevated polysaccharide production. Both mutants were isolated using a combination of chemical mutagenesis and resistance to growth inhibitors. It was found that both mutants elaborated higher polysaccharide levels after 7 days of growth on corn syrup or sucrose, respectively, compared to ATCC 42023. The dry weights of the mutant cells were found not to differ greatly from those of the parent cells whether corn syrup or sucrose served as the carbon source. The pullulan content of the polysaccharide synthesized by the mutants or parent cells on sucrose was consistently lower than polysaccharide synthesized on corn syrup. Using corn syrup as a carbon source, the pullulan content of the polysaccharide elaborated by the parent was higher than either mutant. The inverse was found to occur with respect to pullulan content when the strains were grown on sucrose as a carbon source.