Reduction of acetylene by stationary cultures of free-living Rhizobium sp. under atmospheric oxygen levels.

The reduction of acetylene to ethylene by stationary (non-shaking) cultures of free-living rhizobia under atmospheric oxygen levels has been demonstrated. Under these conditions the development of the activity is inhibited by 10 mM NH4Cl and about 20% of oxygen is required for maximal activity. When the stationary cultures were shaken, oxygen concentrations of 1% and higher were found to be inhibitory. Specific activities of 20 and 40 nmol of acetylene reduced h-1 mg-1 protein were observed.