TABLE 2.
Susceptibility to group A and B colicins and phage φ80
| Straina | Phenotype | Susceptibility tob:
|
||
|---|---|---|---|---|
| ColA | ColB | φ80 | ||
| W3110(pBAD24) | ExbB+ ExbD+ TolQ+ TolR+ | 7, 7, 7 | 7, 7, 7 | 8, 8, 8 |
| RA1051(pBAD24) | ExbB− ExbD− TolQ− TolR− | R, R, R | R, R, R | R, R, R |
| RA1003(pBAD24) | ExbB− ExbD− TolQ+ TolR+ | 7, 7, 6 | 5, 5, 4 | 7, 6, 6 |
| RA1034(pRA002) | ExbB− ExbD− TolQ+ pRA002+ | 6, 6, 6 | 6, 6, 7 | 7, 7, 6 |
| RA1035(pBAD24) | ExbB+ ExbD+ TolQ− TolR− | R, R, 3 | 7, 8, 7 | 7, 8, 9 |
| RA1045(pRA002) | ExbB+ ExbD− TolQ− pRA002+ | R, R, R | R, R, R | 4, 4, 2 |
| RA1044(pBAD24) | ExbB− ExbD+ TolQ+ TolR− | R, R, R | R, R, R | R, R, R |
| RA1045(pBAD24) | ExbB+ ExbD− TolQ− TolR− | R, R, R | R, R, R | R, R, R |
| RA1046(pBAD24) | ExbB− ExbD+ TolQ− TolR− | R, R, R | R, R, R | R, R, R |
| RA1034(pBAD24) | ExbB− ExbD− TolQ+ TolR− | R, R, R | R, R, R | R, R, R |
| RA1051(pRA002) | ExbB− ExbD− TolQ− pRA002+ | R, R, R | R, R, R | R, R, R |
Most strains carried plasmid pBAD24; the exceptions were the strains which carried plasmid pRA002, which encodes TolR. Cells were grown at 37°C with aeration in LB broth supplemented with 100 μg ml−1 ampicillin to mid-exponential phase (an A550 of 0.4, as determined with a Spectronic 20 spectophotometer with a path length of 1.5 cm) and then plated in T-top medium supplemented with 100 μg ml−1 ampicillin and 0.01% (wt/vol) l-arabinose on similarly supplemented T-medium plates. Colicin and phage dilutions were added as 5-μl aliquots, and the plates were incubated at 37°C for 18 h and then scored for clearing.
The values are the highest numbers of dilutions (fivefold dilutions for colicins and 10-fold dilutions for φ80) of the agent that resulted in an evident zone of clearing in the cell lawn. R indicates resistance (i.e., no clearing) with the undiluted colicin or phage stock. The values for three platings are shown for each strain-agent pair.