The growth characteristics of Saccharomycopsis lipolytica: morphology and induction of mycelium formation

When Saccharomycopsis lipolytica was grown on minimal medium supplemented with glucose or n-hexadecane, all the cells of the culture remained in the yeast form. In complex medium, a mixed morphology of yeast and mycelial forms appeared. If the cells were grown on minimal medium supplemented with N-acetylglucosamine as the carbon source, a reproducible system for the production of mycelium was obtained. Neither temperature, pH, nor several other carbon sources were able to induce a reproducible yeast–mycelial transition. Mycelium formation is maximal after 12–15 h of incubation (in the presence of N-acetylglucosamine) and decreases with longer incubating times when N-acetylglucosamine is exhausted. During mycelium formation a considerable increase took place in dry weight; the cell numbers, however, remained almost constant between 12–15 h. Electron microscopy shows mycelium with a smooth surface, a great amount of mitochondria and a low degree of branching.