. 2001 Mar;183(5):1610–1620. doi: 10.1128/JB.183.5.1610-1620.2001

TABLE 5.

Nitrogenase activity in K. pneumoniae strains with pCH7 (R. rubrum draTG) and its response to NH₄Cl in the presence of 50 μM IPTG in the derepression medium

Strains	Chromosomal genotype^a	Gene(s) on plasmids^b	Nitrogenase activity^c
Strains	Chromosomal genotype^a	Gene(s) on plasmids^b	Initial	40 min after NH₄Cl was added (%)^d
UN5522	wt	draTG	810	34 (4)
UN5523	glnB	draTG	760	250 (33)
UN5524	glnK	draTG	<10	<10
UN5525	wt	draTG, nifA	1,000	10 (1)
UN5526	glnB	draTG, nifA	750	190 (25)
UN5527	glnK	draTG, nifA	800	1,100 (138)

wt, wild type.

draTG was from R. rubrum; nifA was from K. pneumoniae.

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 five replicate assays from different individually grown cultures. The deviation is <15%.

NH₄Cl was added at a final concentration of 10 mM. The percentage of initial nitrogenase activity that remained after NH₄Cl treatments is given in parentheses.