TABLE 4.
NH4+ response in R. rubrum glnD mutants
| Strain | Chromosomal genotype | Plasmid | Nitrogenase activity (units) before and after NH4Cl additiona
|
||
|---|---|---|---|---|---|
| Initial | 10 min after | 40 min after | |||
| UR2 | Wild type | None | 300 | <10 | <10 |
| UR1332 | ΔglnD3::aacC1 (opposite) | pUX1224 (5′ region of glnD) | 130 | <10 | <10 |
| UR1333 | ΔglnD4::aacC1 (same) | pUX1224 | 160 | <10 | <10 |
a
Nitrogenase activity was derepressed in MN− under illumination and assayed before NH4Cl addition (initial) and 10 min and 40 min after NH4Cl (10 mM) addition. Each unit of nitrogenase activity is expressed as nanomoles of ethylene produced per hour per milliliter of cells at an optical density at 600 nm of 1. Each activity value is from at least 10 replicate assays from different individually grown cultures. The standard deviation is about 10 to 15%.