This early laboratory study treated yeast and bacteria with uranyl nitrate and found that uranium binds reversibly to proteins and inhibits glucose fermentation and oxidation while leaving the oxidation of acetate, ethanol and some acids untouched. Phosphate, ATP or citrate released the inhibition in living yeast at neutral pH. The authors concluded that uranium acts by binding to the protein part of the cell membrane.
Key numbers
- Glucose fermentation and oxidation in living yeast were inhibited by 7.7 micrograms of uranium per mg dry weight of cells (Summary, p. 178).
- At saturation one yeast cell held 7.06 x 10^8 uranium molecules (Summary, p. 178).
Methods (brief)
Manometric measurement of oxygen uptake and fermentation in yeast and bacterial suspensions and in isolated enzyme systems, with and without uranyl nitrate and added phosphate, citrate or ATP; protein binding was tested with plasma albumin and ultrafiltration.
Evidence fitness
Supports a mechanistic statement that uranyl ions bind proteins and can inhibit glucose metabolism at the cell surface. It does not support human dose-response, dietary exposure or toxicity thresholds.
Limitations
Microorganisms and isolated enzymes only, very high concentrations relative to environmental exposure, and methods from 1948.
Related evidence
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