title: Rapid derepression of in vitro nitrogenase activity in a Rhizobium strain which nodulates legumes and the nonlegume Parasponia.
abstract: Using defined media and controlled gaseous conditions in vitro nitrogenase activity, as monitored by acetylene reduction, was detected after 16 hours of derepression. Specific activity of nitrogenase increased progressively over a period of 100 hours. The method used here utilises rapidly agitated cultures of Rhizobium strain ANU289, incubated at 28°C at cell densities of ca. 1×10(9) cells ml(-1). The optimal medium for rapid derepression contained basic physiological salts with 3 mM glutamate and 50 mM sodium succinate being the only carbon and nitrogen additives. The gas phase was kept constant by a continuous flow of an air-nitrogen mixture with oxygen being maintained at 0.2%. The described culture system provides the opportunity to observe the regulation of nitrogenase activity in a near-chemostat situation.
authors.affiliation: Botany Department, Faculty of Science, Australian National University, Canberra ACT, Australia.
authors.forename: H K
authors.initials: HK
authors.lastname: Mahanty
authors.forename: P M
authors.initials: PM
authors.lastname: Gresshoff