TABLE 2.
Chemotaxis of A. brasilense wild-type strain and cheBR, cheB, and cheR mutants in a temporal gradient assay
| Strain | Response time (s) (mean ± SD)
|
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Malatea
|
Succinate
|
Fructose
|
Galactose
|
Oxygen
|
||||||
| +b | −c | + | − | + | − | + | − | + | − | |
| Wild type | 56 ± 6 | 43 ± 3 | 52 ± 7 | 41 ± 4 | 63 ± 8 | 45 ± 3 | 34 ± 8 | 26 ± 4 | 33 ± 4 | 28 ± 2 |
| cheBR mutant | NRd | NR | NR | NR | NR | >300 | 38 ± 5 | >300 | NR | NR |
| cheB mutant | NR | NR | NR | NR | NR | NR | 82 ± 7 | NR | NR | NR |
| cheR mutant | NR | >300e | NR | NR | NR | NR | NR | NR | NR | NR |
a
Cells were grown with the chemical to be tested as an attractant or repellent and prepared as described in Materials and Methods.
b
+, addition of attractant. The chemicals were tested at a final concentration of 10 mM.
c
−, removal of attractant. The chemical concentration was reduced from 10 mM to 2.5 mM (final).
d
NR, no response, i.e., no change in the swimming bias of cells upon addition or removal of the chemoeffector tested.
e
Cells responded to the removal of the chemoeffector by changing the swimming bias but did not adapt within 300 s of observation.