Effect of molybdenum starvation and tungsten on the synthesis of nitrogenase components in Klebsiella pneumonia.

Klebsiella pneumoniae M5a1 grows well in the presence or absence of molybdenum in media containing excess NH(4) (+). However, growth on N(2) is completely dependent on the presence of molybdenum in the medium. Tungstate competes with the molybdate requirement during growth on N(2). In molybdenum-depleted medium, neither protein component of nitrogenase is active and neither component can be detected antigenically. These data provide evidence that molybdenum is an inducer of nitrogenase synthesis.