TABLE 2.
Nitrogenase activity and nifH::gusA expression of Azoarcus sp. strain BH72 wild-type, BHGLBS (glnB), BHGLKK (glnK), and BHGLKKBS (glnBK) strains grown microaerobically in SM medium supplemented with 10 mM NH4Cl or KNO3a
| Genotype | N source | Nitrogenase activity (nmol of C2H4/mg of protein) | nifH::gusA expression (Miller units) in 1%/20% O2 |
|---|---|---|---|
| Wild type | NH4Cl | n.d. | 80 ± 10/<50 |
| KNO3 | n.d. | 120 ± 10/<50 | |
| N2 | 10,430 ± 530 | 7,200 ± 200/n.dm. | |
| glnB | NH4Cl | n.d. | 100 ± 10/<50 |
| KNO3 | n.d. | 150 ± 20/<50 | |
| N2 | 9,240 ± 150 | 6,320 ± 410/n.dm. | |
| glnK | NH4Cl | n.d. | 90 ± 10/<50 |
| KNO3 | n.d. | 140 ± 10/<50 | |
| N2 | 9,460 ± 460 | 6,910 ± 390/n.dm. | |
| glnBK | NH4Cl | 70 ± 10 | 710 ± 30/<50 |
| KNO3 | 4,010 ± 360 | 2,860 ± 60/700 ± 60 | |
| N2 | 7,320 ± 410 | 7,100 ± 450/n.dm. |
a
Data were obtained from three parallel measurements from two independent experiments and are given with standard deviations. n.d., not detected; n.dm., not determined (cells did not grow under atmospheric O2 concentrations (20%) with N2 as the sole nitrogen source).