Table I Summary of tobramycin MIC assays for P. aeruginosa mutantsa
Genotype and allelesStrainsTob MIC (μg/ml)
WTMPAO10.5–1
ftsH gene deletionΔftsH0.03–0.06
ibpA in-frame deletionΔibpA0.5–1
ibpA gene inactivation with lux insertibpA-lux0.5–1
Control containing lux insertPKH1810.5–1
Control for Tn insertionPA33030.5–1
clpB single mutant, Tn 1076(2565)clpB (PW8651)1
clpB single mutant, Tn 1076(2565)clpB (PW8652)1
PA0779 single mutant, Tn 2245(2400)PA0779 (PW2411)1
PA0779 single mutant, Tn 1351(2400)PA0779 (PW2414)1
PA0779 single mutant, Tn 1345(2400)PA0779 (PW2413)1
hslV single mutant, Tn 223(534)hslV (PW9487)0.25
hslV single mutant, Tn 168(534)hslV (PW9485)0.5
hslV single mutant, Tn 244(534)hslV (PW9486)0.5–1
double mutant ibpA/clpBibpA/PW8651 (1,2,3)0.5, 0.5, 0.5
double mutant ibpA/clpBibpA/PW8652 (1,2,3)0.5, 0.5, 0.5
double mutant ibpA/PA0779ibpA/PW2411 (1,2,3)0.5, 0.5, 0.5
double mutant ibpA/PA0779ibpA/PW2414 (1,2,3)0.5, 0.5, 0.5
double mutant ibpA/PA0779ibpA/PW2413 (1,2,3)0.5–1, 0.5, 0.5
double mutant ibpA/hslVibpA/PW9487 (1,2,3)0.25, 0.25, 0.25
double mutant ibpA/hslVibpA/PW9485 (1,2,3)0.25, 0.25, 0.25
double mutant ibpA/hslVibpA/PW9486 (1,2,3)0.25, 0.25, 0.25
  • a The sequence-verified transposon insertion mutants (Tn) are as reported in Held et al. (17), and information of mutant-specific insertion sites (gene lengths), e.g. 1,076(2,565) and library names, e.g. clpB (PW8651) are indicated in the table. Two lines of ibpA/clpB mutants, three lines of ibpA/PA0779, and ibpA/hslV were examined. For each double mutant line, three independent transformants (1,2,3) were assayed. Tobramycin MIC was defined as the lowest antibiotic concentration preventing the lawn growth of the spotted cells. A listing of a range of concentration levels indicates that a very thin lawn was observed at the lower concentration and this lawn was entirely abolished at the higher concentration in the range. See Figure S8 for additional details.