Yoshimura F, Nikaido H
J Bacteriol. 1982 Nov;152(2):636-42. doi: 10.1128/jb.152.2.636-642.1982.
Pseudomonas aeruginosa is usually resistant to a wide variety of antibacterial agents, and it has been inferred, on the basis of indirect evidence, that this was due to the low permeability of its outer membrane. We determined the permeability of P. aeruginosa outer membrane directly, by measuring the rates of hydrolysis of cephacetrile, cephaloridine, and various phosphate esters by hydrolytic enzymes located in the periplasm. The permeability to these compounds was about 100-fold lower than in the outer membrane of Escherichia coli K-12. Also, we found that the apparent Km values for active transport of various carbon and energy source compounds were typically higher than 20 microM in P. aeruginosa, in contrast to E. coli in which the values are usually lower than 5 microM. These results also are consistent with the notion that the P. aeruginosa outer membrane indeed has a low permeability to most hydrophilic compounds and that this membrane acts as a rate limiting step in active transport processes with high Vmax values.
铜绿假单胞菌通常对多种抗菌剂具有抗性，基于间接证据推测，这是由于其外膜通透性较低所致。我们通过测量周质中水解酶对头孢乙腈、头孢菌素和各种磷酸酯的水解速率，直接测定了铜绿假单胞菌外膜的通透性。这些化合物在铜绿假单胞菌外膜中的通透性比大肠杆菌K-12外膜低约100倍。此外，我们发现，与大肠杆菌中通常低于5 microM的值相比，铜绿假单胞菌中各种碳源和能源化合物主动转运的表观Km值通常高于20 microM。这些结果也与以下观点一致，即铜绿假单胞菌外膜对大多数亲水性化合物确实具有低通透性，并且该膜在具有高Vmax值的主动转运过程中充当限速步骤。
