Oxygen - Factors Influencing Functions of Nitrogenase
Oxygen is a strong inhibitor of N2-fixation because it blocks both the synthesis as well as the activity of nitrogenase. There are N2-fixers which are anaerobes and there are those which are aerobes. The problem of oxygen in anaerobes is taken care of by their very anaerobic mode of nutrition. The problem is really with aerobes like Azotobacter which require oxygen to fix nitrogen and grow at the expense of nitrogen.