OBSERVATION OF ALCOHOLIC FERMENTATION IN ACANTHAMOEBA-CASTELLANII BY MEANS OF NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

Acanthamoeba castellanii is a small soil amoeba which is found as a trophozoite where the cells grow and reproduce, and as a cyst in which cells are metabolically dormant. Using nuclear magnetic resonance spectroscopy (NMR), we have observed alcoholic fermentation in this organism. Alcohol dehydrogenase (ADH) activity and lactate dehydrogenase (LDH) activity are very low in the cells at the beginning of the logarithmic growth phase (<10 units) but increase rapidly with cell density. During the stationary phase, alcoholic fermentation is quantitatively more important than lactic fermentation. LDH activity varies between 20 and 50 units while that of ADH ranges from 40 to 120 units. During encystment, the cells can meet their increased energetic needs by alcoholic fermentation. Under these conditions, up to 10% of the dry weight of the cells can be transformed into alcohol. Intracellular substrates are used for alcohol fermentation.