Table 2.

In vivo nitrogenase activities of R. capsulatus B10S in the presence of urea

Nitrogen sourceNickel added (μM)Nitrogenase activitya (nmol of ethylene produced/ [mg of protein × h])
AmmoniumNone3.6 ± 1.7
SerineNone1,069.4 ± 19.6
UreaNone665.9 ± 50.2
Urea0.4941.9 ± 82.7
Urea6.0995.1 ± 85.2
Urea100.0688.6 ± 145.7
  • a In vivo nitrogenase activities were analyzed by the acetylene reduction assay as described by Wang et al. (31). The results represent the means and standard deviations of at least three independent measurements.