%0 Journal Article %A HEWINSON, R. GLYN %A LANE, DAVID C. %A SLACK, MARY P. E. %A NICHOLS, WRIGHT W. %T The Permeability Parameter of the Outer Membrane of Pseudomonas aeruginosa Varies with the Concentration of a Test Substrate, Cephalosporin C %D 1986 %J Microbiology, %V 132 %N 1 %P 27-33 %@ 1465-2080 %R https://doi.org/10.1099/00221287-132-1-27 %I Microbiology Society, %X SUMMARY: The permeability parameter (C) for the movement of cephalosporin C across the outer membrane of Pseudomonas aeruginosa was measured using the widely accepted method of Zimmermann & Rosselet. In one experiment, the value of C varied continuously from 4∙2 to 10∙8 cm3 min−1 (mg dry wt cells)−1 over a range of concentrations of the test substrate, cephalosporin C, from 50 to 5 μm. Dependence of C on the concentration of test substrate was still observed when the effect of a possible electric potential difference across the outer membrane was corrected for. In quantitative studies of β-lactam permeation the dependence of C on the concentration of β-lactam should be taken into account. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-132-1-27