TABLE 3.
Glycine betaine and proline betaine uptake activities in S. meliloti wild-type (GMI211) and betS mutant (UNA316) strainsa
| Growth conditions | Uptake activity (nmol/min/mg of protein)
|
|||
|---|---|---|---|---|
| Glycine betaine
|
Proline betaine
|
|||
| GMI211 | UNA316 | GMI211 | UNA316 | |
| Control | 3.9 ± 0.1 | 3.6 ± 0.6 | 1.1 ± 0.2 | 1.0 ± 0.1 |
| + Glycine betaine (1 mM) | 10.5 ± 0.9 | 10.6 ± 0.8 | 2.0 ± 0.3 | 1.9 ± 0.2 |
| + NaCl (0.3 M) | 18.4 ± 1.4 | 7.0 ± 1.0 | 7.2 ± 0.4 | 3.0 ± 0.5 |
| + NaCl (0.3 M) + glycine betaine (1 mM) | 20.0 ± 4.0 | 7.7 ± 0.6 | 7.8 ± 0.9 | 3.6 ± 0.5 |
a
Cells were grown for 16 h in low-osmolarity MCAA medium (control) or in MCAA medium supplemented as indicated. Uptake measurements were done at a final substrate concentration of 40 μM. Values are means from duplicates of three independent cultures, and standard deviations are also shown.