부산대학교 도서관

N 2 fixation is an extremely O 2 -sensitive process. N 2 -fixing bacteria (diazotrophs) have therefore evolved a variety of strategies by which they maintain an active nitrogenase in the presence of atmospheric O 2 and, in some cases, of O 2 generated photosynthetically. In this review, the effects of O 2 on nitrogenase activity and synthesis are described, as are the mechanisms by which diazotrophs limit O 2 damage to nitrogenase. These mechanisms are classified as behavioural strategies, physical barriers or physiological and biochemical strategies. Individual diazotrophs frequently employ a combination of these. In addition, the particular problems faced by the O 2 -evolving cyanobacteria are discussed.