MUTANT OF ANABAENA SP CA WITH OXYGEN-SENSITIVE NITROGENASE ACTIVITY

Studies on the O2 protection mechanism for nitrogenase in a mutant (PM10) of Anabaena sp. CA indicated that the ability to protect nitrogenase from O2 was functionally impaired. Growth rates of PM10 were substantially improved when cells were cultured under microaerobic conditions. Nitrogenase activity was totally inhibited by exposure to O2 for 30 min; partial restoration of activity was attained when cell suspensions were subsequently made microaerobic. Experiments in which induction of nitrogenase activity was followed indicated that the synthesis of the O2 protection mechanism was temporally separated from synthesis of heterocysts and nitrogenase. © 1979.