The Transition from Yeast-like to Chlamydospore Cells in Pullularia pullulans

Abstract

The transition from yeast-like to chlamydospore cells was induced by growing Pullularia pullulans on an unbuffered glucose medium with a limiting nitrogen source. The kinetics of cell growth and extracellular polymer production were determined. Changes in cell morphology were apparent during the whole process. Yeast-like cells became progressively enlarged before producing chlamydospores. The proportion of sugars increased at the expense of proteins and nucleic acids during the transition. Quantitative and qualitative changes in phospholipids were observed. Fatty acid unsaturation decreased as the cells grew older. Enzymic cell-wall analysis also revealed differences in the wall structures of the different forms. Protoplasts were easily prepared from yeast-like cells, but could not be produced from other cell forms.