Auxotrophic requirement for sporangiospore--yeast transformation of Dimorphomyces diastaticus strain C 12.

The filamentous microorganism tentatively known as Dimorphomyces diastaticus originally isolated from fermenting soursop extract, in contradistinction grew in the considiogeneous form in glucose-ammonium sulphate-basal salts buffered medium which induced polar budding yeast cells of another dimorphic microorganism, D. pleomorphis (1). Further experiments using this medium showed that a number of growth factors including inositol, thymine and uracil separately incorporated inducted yeast morphology. Carbon substrates gave rise to polar budding yeast cells in the following order: galactose, malic acid, maltose, but mycelial fragments were preponderant in the reverse order. There was no growth with citric acid as substrate. With maltose-substrate and uracil incorporation in buffered basal salts medium, only polar budding yeast cells were induced, while granular particles abound with thymine supplementation. It was concluded that D. diastaticus strain C12 auxotrophically required a dissacharide, maltose, and pyrimidine base, uracil, for sporangiospore-yeast transformation in buffered ammonium sulphate-basal salts medium, pH 3.5.