Acute toxicity of 16 water-soluble chemicals to the fungus Geotrichum candidum measured by reduction in glucose uptake.
A method for the estimation of chemical inhibition of glucose uptake by the fungus Geotrichum candidum was developed. Inhibition of glucose uptake was measured in cultures of germinated spores of G. candidum treated for 4 hr with 16 different water-soluble chemicals. The assay was performed in microtitre trays. Under control conditions the fungus had a glucose uptake of 200-230 mug/ml (non-inhibited cultures). The glucose assay was linear up to 600 mug glucose/ml with a detection limit of 12.2 mug glucose/ml. All of the chemicals inhibited glucose uptake. IC(50) values were extrapolated from dose-response curves. The IC(50) values ranged from 0.006 (mercuric chloride) to 1500 mM (methanol). A highly significant correlation between IC(50) values in the fungal test and human lethal blood concentrations (r = 0.83) was found for the 16 chemicals. A significant correlation was also found between IC(50) from the assay with the fungus and the minimal inhibition concentration in bacteria (r = 0.78) and IC(50) values obtained with [(3)H]proline incorporation in cell cultures (r = 0.87).
Jacobsen
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Department of Life Sciences and Chemistry, Roskilde University, Box 260, DK-4000 Roskilde, Denmark.