Continuous non-destructive determination of nitrogenase activity in microbial cultures

Abstract

The dinitrogen fixing enzyme nitrogenase (nitrogen:(acceptor) oxidoreductase) (EC 1.7.99.2) is monitored by its ability to reduce acetylene to ethylene. Low, non-inhibitory concentrations of acetylene (~10−7 mol/litre) are mixed with the gas flow aerating microbial cultures, and acetylene and ethylene in the effluent gas are determined by gas chromatography. The procedure is safe, simple and is carried out in situ without disturbing the growing culture. Transient changes in nitrogenase activity are easily detected. The technique may be automated.