Ammonium-nitrogen assimilation and nitrogen fixation in azospirillum lipoferum and azospirillum brasilense

1990 ◽  
Vol 10 (5) ◽  
pp. 411-417
Author(s):  
B. T. Shawky
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Nitrogen Assimilation ◽  
Ammonium Nitrogen ◽  
Azospirillum Lipoferum

Pectin decomposition and associated nitrogen fixation by mixed cultures of Azospirillum and Bacillus species

1992 ◽  
Vol 38 (8) ◽  
pp. 794-797 ◽  
Author(s):  
K. M. Khammas ◽  
P. Kaiser
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Nitrogenase Activity ◽  
Bacillus Species ◽  
Azospirillum Lipoferum ◽  
Pectin Degradation ◽  
Efficient Utilization ◽  
Fermentation Products ◽  
Pure Cultures ◽  
Azospirillum Amazonense

Cocultures of different Azospirillum species with Bacillus polymyxa or Bacillus subtilis allow the efficient utilization of pectin as carbon and energy sources for nitrogen fixation. The nitrogenase activity obtained with cocultures was as high as 30–80 nmol C2H4 h−1 mL−1, a much higher value than that obtained with pure cultures of either Azospirillum (up to 13 nmol C2H4 h−1 mL−1) or B. polymyxa (up to 2 nmol C2H4 h−1 mL−1) alone. To establish to what extent each partner contributed to nitrogenase activity, acetylene reduction was assayed as a function of time and it was also measured on Azospirillum cultivated in the cultures filtrates of the Bacillus. The results suggested that the nitrogenase activity was mostly produced by Azospirillum. The nitrogenase activity occurred at the expense of the degradation and fermentation products of the pectin. The new pectinolytic species, Azospirillum irakense, utilized both degradation and fermentation products of pectin, whereas the nonpectinolytic strains (Azospirillum brasilense, Azospirillum lipoferum, Azospirillum amazonense) utilized only the fermentation products of pectin, including acetic and succinic acids. These cocultures can be considered as metabolic associations, where the Bacillus produces degradation and fermentation products of pectin, which can be used by Azospirillum species. Key words: cocultures, nitrogen fixation, pectin degradation, Azospirillum, Bacillus, metabolic association.

Temperature sensitivity of nitrogen fixation in Azospirillum spp.

1992 ◽  
Vol 38 (12) ◽  
pp. 1238-1241 ◽  
Author(s):  
Anil K. Tripathi ◽  
Walter Klingmüller
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Nitrogenase Activity ◽  
Lacz Fusion ◽  
Optimum Growth ◽  
Azospirillum Lipoferum ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
The Impact ◽  
Key Words Temperature

Azospirillum brasilense and Azospirillum lipoferum showed optimum acetylene-reducing activity at 25 and 30 °C, respectively, although both the bacteria grew optimally at 35 °C. Azospirillum halopraeferens displayed optimum growth and acetylene-reducing activity at 40–41 °C. Our experiments indicated that expression of nif genes was generally more sensitive to temperature than was nitrogenase activity. The NifA-dependent activation of a heterologous nifH–lacZ fusion was used to assess the impact of temperature on native NifA activity of A. brasilense and A. lipoferum. Maximum NifA activity was observed at 25 °C in A. brasilense and at 30 °C in A. lipoferum. Key words: temperature, nitrogen fixation, nifH–lacZ fusion, NifA activity, Azospirillum.

Nitrogen Fixation and Nitrate Respiration by A zospirillum brasilense

1983 ◽  
Vol 38 (7-8) ◽  
pp. 571-577 ◽  
Author(s):  
Hermann Bothe ◽  
Gislene Barbosa ◽  
Johanna Dobereiner
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reduction ◽  
Azospirillum Brasilense ◽  
Nitrate Respiration ◽  
Present Communication ◽  
Reaction Proceeding ◽  
Physiological Properties ◽  
Assimilatory Nitrate Reduction

The O2- sensitivitiy of N2-fixation by the carotenoid forming strain Azospirillum brasilense Cd and the colourless strain Sp 7 is compared in the present communication. As no difference in the reaction is observed with both strains, it is concluded that carotenoids do not protect nitrogenase from damage by O2. Azospirillum spp. have also been shown to perform NO3-- dependent N2-fixation. The physiological properties of this reaction are described in more detail in the present communication. Evidence is presented that NO3-- dependent N2-fixation is a transitory reaction, proceeding only as long as the enzymes of assimilatory nitrate reduction are synthesized by the cells.

Sign in / Sign up

Export Citation Format

Share Document