DIGESTION OF SACCHAROMYCES-CEREVISIAE BY ACANTHAMOEBA-CASTELLANII

The digestion of Saccharomyces cerevisiae by Acanthamoeba castellanii, at different times after feeding, has been examined by cytochemical techniques at electron microscope level and by measurement of yeast viability. The measurement of viability, combined with cytochemistry is presented as a novel method of examining the progress of digestion. Particular attention has been given to the temporal development of digestion. Vacuoles, probably primary lysosomes, have been identified containing acid phosphatase activity within minutes of feeding and these accumulate around and fuse with phagocytic vacuoles. Acid phosphatase levels in the digestive vacuoles appeared highest at 20 to 40 minutes. Yeast digestion was observed and yeast viability began to decline at this time. Mixing of autophagic and heterophagic material was also observed. At least half of the yeast population was still viable after 90 minutes. Our method (p-nitrophenyl phosphate) of enzyme localization has demonstrated plasma membrane associated acid phosphatase activity. © 1979 Springer-Verlag.