FIG. 3.
Irreversible φ80 adsorption. aroB strains expressing TonB at various levels were grown as indicated in Materials and Methods and assayed for the ability to irreversibly adsorb bacteriophage φ80 as previously described (27), with 3 × 108 cells and φ80 at a multiplicity of infection of 1.0. Values are presented as the percentage of phage remaining following the indicated incubation; thus, the lower the value, the higher the relative TonB activity. Relative transport rates, calculated with the data collected at 0 and 10 min and expressed as 107 PFU adsorbed per minute, are as follows: KP1270/pACYC184 (TonB = 1), 1.6 ± 0.3; KP1414/pACYC184 (TonB =1), 1.9 ± 0.2; KP1406/pACYC184 (TonB = 0), 0.2 ± 0.2; KP1406/pKP325 (TonB = 0.12), 0.9 ± 0.4; KP1408/pKP325 (TonB = 0.004), −0.1 ± 0.2; and KP1406/pKP299 (TonB = 2.5), 0.7 ± 0.2.