TABLE 2.
Hydrogenase activities of the wild-type B10 and hupT BSE8 strains from R. capsulatus, complemented with wild-type and mutant hupT genesa
| Growth condition | Fructose | Hydrogenase activity (μmol of reduced MB h−1 mg of protein−1) in strain:
|
|||||
|---|---|---|---|---|---|---|---|
| B10
|
BSE8
|
||||||
| pAC394 (wild-type HupT) | pAC395 (H217N HupT) | pAC396 (PASΔHupT) | pAC394 (wild-type HupT) | pAC395 (H217N HupT) | pAC396 (PASΔHupT) | ||
| Anaerobiosis | |||||||
| −H2 | − | 9 ± 1 | 15 ± 1 | 12 ± 1 | 26 ± 1 | 34 ± 2 | 54 ± 1 |
| + | 11 ± 2 | 11 ± 1 | 13 ± 2 | 7 ± 1 | 32 ± 1 | 48 ± 3 | |
| +H2 | − | 25 ± 1 | 28 ± 1 | 34 ± 4 | 29 ± 1 | 43 ± 1 | 40 ± 9 |
| + | 18 ± 1 | 18 ± 1 | 21 ± 2 | 25 ± 1 | 39 ± 4 | 27 ± 2 | |
| Aerobiosis | |||||||
| −H2 | − | 10 | 11 | NDb | 19 ± 1 | 66 ± 11 | 72 ± 4 |
| + | 5 | ND | ND | 7 ± 1 | 81 ± 5 | 61 ± 1 | |
| +H2 | − | 45 ± 5 | 36 ± 4 | 42 ± 5 | 58 ± 3 | 67 ± 6 | 65 ± 8 |
| + | 44 ± 2 | 36 ± 3 | 44 ± 9 | 50 ± 3 | 54 ± 9 | 60 ± 12 | |
a
Cells were grown overnight in 10-ml tubes under anaerobiosis under light (−H2, MN medium; +H2, MG medium) or in 20-ml flasks containing 3 ml of MN medium under aerobiosis (±10% H2) in the dark. Where indicated, fructose (3 mM) was added at the beginning of growth. Hydrogenase activity was assayed with methylene blue and was expressed as micromoles of reduced MB per hour per milligram of protein. The results represent the means of at least three independent measurements ± standard errors.
b
ND, not determined.