Über die Aufnahme von radioaktivem Phosphorisotop P32 15 durch Colibakterien

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Abstract
The uptake of P (an important component of nucleoproteins) from various culture media by Escherichia coli, using a radioisotope technic was determined. Uptake of p32 from a radioactive nutrient broth averaged 4% but some individual values were as high as 10% of the P32 present. In mixtures of broth and synthetic medium this average percentage rose to 6.5; in P-poor broth to 15% and finally in a synthetic medium containing only 27 [mu]g P per cc. up to 35%. There was a positive correlation between growth of E. coli and its p32 uptake. Further expts. showed that 3% of the P32 available was taken up by diffusion alone, excluding mere adsorption on the cell membrane. After 46 hours "resting" metabolism at a temp. of 5[degree]C, the compounds into which the p32 was converted no longer dialyze. However, dialysis yields over 40% of p32 absorbed from a phosphate buffer, only about 4% after 3 washings with dist. water. In bacteria killed by formalin or heat no back-dialysis of P32 occurs. Technics are described.

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