01745naa a2200205 a 450000100080000000500110000800800410001902400440006010000210010424501050012526000090023052011320023965000170137165300150138865300160140365300220141970000170144170000190145877300620147721351722021-10-08       1981    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1007/BF004059152DOI1 aVOLPON, A. G. T.  aPhysiology of nitrogen fixation in Azospirillum lipoferum Br 17 (ATCC 29709).h[electronic resource]  c1981  aChanges of cellular activities during batch cultures with Azospirillum lipoferum strain Br 17 (ATCC 29 709) were observed within the growth cycle, at optimal pO2 (0.002-0.003 atm). The relative growth rate for cells growing with N2 as sole nitrogen source during log phase was u=0.13 h-1 and the doubling time was 5.3 h. Nitrogenase activity was not accompanied by hydrogen evolution at any growth stage, and a very active uptake hydrogenase was demonstrated. The hydrogenase activity increased towards the end of the growth period when glucose became limiting and N2 fixation reached its maximal specific activity. Oxygen consumption and oxygen tolerance at the various growth stages, increased simultaneously with the uptake hydrogenase activity indicating a possible role of this enzyme in an oxygen protection mechanism of A. lipoferum nitrogenase. The efficiency of nitrogen fixation expressed as mg total nitrogen fixed in cells and supernatant per g glucose consumed, was 20 at the early log phase and increased to 48 at the late log phase. About 25% of the total fixed nitrogen was recovered in the culture supernatant.  aAzospirillum  aEfficiency  aHydrogenase  aOxygen protection1 aDE POLLI, H.1 aDOBEREINER, J.  tArchives of Microbiologygv. 128, n. 4, p. 371-375, 1981.