Table 2.
Phenotypes of P. luminescens TT01 transconjugants, overexpressing dam gene (pBB-dam) and control (pBBR1MCS-5).
| Tested phenotypesa | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Strain | Btb adsorptionb | Bioluminescencec | Antibiotic productiond | Sheep blood hemolysise | Motilityf | Lipolysis ofg | Growth rate (h−1)h | Mutation ratei | ||||
| Tween 20 | Tween 40 | Tween 60 | Tween 80 | Tween 85 | ||||||||
| TT01 WT | G | + | + | − | ++ | + | + | + | + | − | ND | ND |
| TT01+pBBR1MCS-5 | G | + | + | − | ++ | + | + | + | + | − | 0.636 | 4.80 × 10−8 |
| TT01+pBB-dam | G | + | + | − | + | + | + | + | + | − | 0.647 | 3.84 × 10−8 |
All plates were incubated for 2 days at 28°C before assays were interpreted, unless otherwise indicated. Routinely tested phenotypes on the WT strain are indicated for comparison.
Btb, bromothymol blue; G, green-blue colonies on NBTA medium.
+, Luminescence detected by visual observation in a dark room.
+, Halo size (>25 mm) of growth inhibition of Micrococcus luteus.
-, No halo of hemolysis detected
++, Large spreading area (halo size >20 mm); +, reduced spreading area (halo size < 20 mm) after 30 h of incubation.
+, Halo of precipitation; −, no halo of precipitation
Growth rate was estimated on 4 independent biological replicates, using serial dilution of the inoculum as described in the method section. Differences were not significant (p = 0.92, Student t-test). ND, not done.
Spontaneous mutation rate per CFU was assessed by quantifying the number of rifampicin-resistant CFU arising in the total population after overnight growth in liquid medium. Presented values are the mean of 3 independent experiments. Differences were not significant (p = 0.73, Student t-test).