scholarly journals Oxygen concentration, nitrogenase activity and heterocyst frequency in the leaf cavities ofAzolla filiculoidesLam

1989 ◽  
Vol 59 (3) ◽  
pp. 283-287 ◽  
Author(s):  
M. Grilli Caiola ◽  
A. Canini ◽  
D. Moscone
Keyword(s):  
Oxygen Concentration ◽  
Nitrogenase Activity ◽  
Heterocyst Frequency

scholarly journals Sensitivity to Oxygen of Nitrogenase Activity in Rhizobium Strain ANU289 of the Non-legume Parasponia (Ulmaceae)

1984 ◽  
Vol 37 (2) ◽  
pp. 31 ◽  
Author(s):  
S S Mohapatra ◽  
PM GresshoffA
Keyword(s):  
Carbon Source ◽  
Gas Phase ◽  
Cell Density ◽  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Nitrogenase Activity ◽  
Rhizobium Strain ◽  
Low Oxygen ◽  
Liquid Cultures ◽  
Low Oxygen Tension

Nitrogenase activity can be detected in Rhizobium strain ANU289 of Parasponia in shaken liquid cultures. A combination of consistently low oxygen tension and appropriate cell density was found to be essential for rapid initiation and high specific rates (in the range of 50-60 nmoles of ethylene per milligram protein per hour). In the presence of succinate as carbon source and an oxygen concentration of 0�25% (v/v) in the gas phase, nitrogenase activity developed after incubation for 24 h. The requirement for an oxygen concentration in the range of O� 1 to 0�35% for derepression indicated a lack of any inherent tolerance to higher oxygen levels and thus suggests that plant-derived mechanisms are responsible for protection by oxygen in the nodule.

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