TABLE 4 .
Relative copy number of aadB in recA::Tc isolates with increased tobramycin resistance
| Strain | aadB relative copy no.b | MIC (µg/ml) |
|---|---|---|
| recA::Tc | 2.49a | 8 |
| hetR-recA-1-1 | 3.34 | 16 |
| hetR-recA-1-2 | 3.15 | 64 |
| hetR-recA-1-3 | 2.85 | 16 |
| hetR-recA-1-4 | 2.64 | 32 |
| hetR-recA-1-5 | 2.63 | 16 |
| hetR-recA-1-10 | 2.72 | 96 |
a
The recA::Tc control sample was used as a control in three independent experiments; the value shown represents the average relative copy number across the three experiments.
b
Relative copy number of aadB normalized to aacA4 was measured using gDNA isolated from a recA transposon mutant and 6 independently isolated derivatives with increased tobramycin resistance. Data shown are from a single sample for each strain. None of the tobramycin-resistant recA::Tc isolates exhibit increased copy number of aadB, suggesting that gene amplification of aadB in wild-type cells is RecA dependent.