Glutamate Synthase from Azospirillum Brasilense: Partial Purification and Characterization

Glutamate synthase (E.C.1.4.1.13) has been detected in Azospirillum Brasilense Sp6. The enzyme activity was tested under different growth conditions, the specific activity of the enzyme being higher when the microorganism was grown under limiting concentrations of ammonia. Azospirillum Brasilense Sp6 exhibits also glutamate dehydrogenase activity (E.C.1.4.1.2): the maximum specific activity was found with an excess of ammonia in the growth medium. Thus, as shown for other nitrogen fixing microorganisms, the levels of the two enzymes are inversely correlated, their physiological role in the route of nitrogen metabolism strictly depending on the availability of ammonia in the growth culture.