TABLE 3.
Expression of β-lactamases in P. aeruginosa and E. coli
| Strain and plasmid | Relevant property(ies) | β-Lactamase activitya
|
|
|---|---|---|---|
| Noninduced | Inducedb | ||
| P. aeruginosa | |||
| PAO1 | Wild type | 15.4 ± 7.8 | 162.2 ± 25.5c |
| PAOampR | ampR::aacC1 | 185.0 ± 8.9d | 126.0 ± 46.0 |
| PAOampR/pSJ06 | ampR::aacC1/ampR+ | 13.0 ± 5.0e | 169.1 ± 22.7c |
| E. coli | |||
| DH5α/pKKF0679 | ND | ND | |
| DH5α/pSJ06 | ampR+ | ND | ND |
| DH5α/pSJ02 | ampC+ | 1.4 ± 0.0f | 0.2 ± 0.1f |
| DH5α/pSJ02/pSJ06 | ampC+ampR+ | 5.9 ± 0.5g | 13.0 ± 1.6c,g |
| DH5α/pKKF0675 | poxAB+ | 19.5 ± 0.6f | 13.8 ± 2.1f |
| DH5α/pKKF0675/pSJ06 | poxAB+ampR+ | 6.9 ± 0.8h | 0.5 ± 0.2c,h |
a
One milliunit of β-lactamase is defined as 1 nanomole of nitrocefin hydrolyzed per minute per microgram of protein. ND, nondetectable.
b
Induction was carried out using 50 μg/ml and 500 μg/ml of benzylpenicillin for E. coli and P. aeruginosa, respectively.
c
P value of <0.05 compared between noninduced and induced.
d
P value of <0.05 compared between PAO1 and PAOampR.
e
P value of <0.05 compared between PAOampR and PAOampR/pSJ06.
f
P value of <0.05 in a comparison of DH5α/pKKF0679 with DH5α/pSJ02 and DH5α/pKKF0675.
g
P value of <0.05 compared between DH5α/pSJ02 and DH5α/pSJ02/pSJ06.
h
P value of <0.05 compared between DH5α/pKKF0675 and DH5α/pKKF0675/pSJ06.