TABLE 4.
Average growth yields of wild-type and exonuclease null mutant cells
| Strain | Presence or mutation ofa:
|
Average yield (fold) (±SD)b | |||
|---|---|---|---|---|---|
| xonA (ExoI) | recJ (RecJ) | xseA (ExoVII) | exoX (ExoX) | ||
| Wild type | + | + | + | + | 223 ± 103 |
| xonA strain | − | + | + | + | 3.5 ± 1.1 |
| recJ strain | + | − | + | + | 4.0 ± 3.2 |
| xseA strain | + | + | − | + | 2.6 ± 0.5 |
| yobC strain | + | + | + | − | 1,458 ± 710 |
| xonA yobC strain | − | + | + | − | 2.3 ± 1.4 |
| xonA xseA strain | − | + | − | + | 2.0 ± 0.2 |
| recJ xseA strain | + | − | − | + | 1.4 ± 1.1 |
| xonA recJ yobC strain | − | − | + | − | 2.9 ± 0.6 |
| xonA xseA yobC strain | − | + | − | − | 2.3 ± 1.4 |
| xonA recJ xseA yobC strain | − | − | − | − | 3.0 ± 2.7 |
a
+, presence of a gene; −, mutation of a gene. Experiments were performed several times for each mutant (n = 2 to 4).
b
Cells were grown in M63 minimal medium supplemented with 0.1% ultra-pure sonicated salmon sperm DNA as the sole source of carbon and energy. Growth yields were determined by dividing the number of cells after 48 h of incubation by the number of cells at inoculation. SD, standard deviation.