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Abstract
Leakage of 260 mμ-absorbing cell constituents from Pseudomonas aeruginosa was enhanced with increasing concentrations of Polysorbate 80 up to a characteristic maximum at 0·125 %. This relationship applied at 4°, 18° or 37° at bacterial concentrations between 1 × 108 and 9 × 108/ml. and for three strains of this organism, but did not apply with Escherichia coli. Uptake of a fluorescent dye was also greatest at 0·125 % Polysorbate 80. Increasing concentration of NaCl in the suspending liquid progressively decreased leakage. In buffer between pH 5·7 and 9·5, the low degree of leakage varied insignificantly. Polysorbate-treated organisms consistently leaked more readily and also showed greater percentage viability losses on rapidly changing the pH, temperature or NaCl concentration of the suspending solution. There was little correlation between loss of viability and leakage. There was a correlation between loss of viability and the magnitude of the sudden change in any of the colligative properties of the organism’s environment. Uptake of Polysorbate from aqueous solution at 20° was rapid. These results supported the hypothesis that Polysorbate 80 had an immediate effect on the permeability barrier of the cell.
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