In nitrogen-poor environments,diazotrophic bacteriaplay avital role for an increased input of metabolically activenitrogen [2]. Their ability to use the nitrogenase enzymecomplex to convert atmospheric dinitrogen into ammonia iskey not only fortheir own survival but also for enriching thepool of biologically active nitrogen in their habitat. Nitrogenase enzyme is extremely sensitive to oxygen, anddifferent strategies have evolved in different biologicalsystems to protect this enzyme from irreversible degradation