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Abstract
SUMMARY: The effects of alkali metal ions on the growth of Escherichia coli have been compared with those for Staphylococcus aureus (pyogenes). Only rubidium could substantially support the growth of both organisms. The efficiency of rubidium as a growth promoter varied with both the potassium and rubidium content of the medium. The uptake of potassium and rubidium during the growth of E. coli was examined using radio-isotopes as tracers, and the velocities of uptake, the accumulation and internal concentrations of these cations were calculated. Potassium was taken up rapidly early in growth and this uptake was inhibited by rubidium, which itself was taken up, and in greater amounts than potassium. Escherichia coli differed from S. aureus in that the former readily leaked both cations when growth slowed down. Rubidium leaked out early in growth only to be taken up again. The two ions appeared to compete for influx and efflux.
- Accepted:
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