A Rapid Cell Volume Assay for Fungitoxicity Using Fungus Spores

In investigations of the physiology of spores of the cellulolytic fungus Myrothecium verrucaria, it was observed that rapid swelling and germina-tion occur in the presence of sugar and yeast extract. This swelling is not a purely osmotic phenomenon but is rather a typical growth process since more or less parallel increases in dry weight occur. Increases in cell volume of the order of 4 to 6 fold occur in about three hours and can be measured easily by centrifugation. Since the rate of swelling is markedly affected by toxic substances, it was reasoned that an ex-tremely rapid bioassay for fungitoxic compounds could be based on this inhibition of swelling. The time for screening or evaluating such compounds