![]() Therefore, knowledge of the bioenergetic status of azospirilla is necessary for a more complete understanding of the bacterial-plant interaction.Īccording to the chemiosmotic theory, cells store energy generated during respiration by forming both a charge gradient (membrane potential, ΔΨ) and a chemical gradient across a membrane system. These activities rely on the bioenergetic status of the cell. ![]() Some relevant issues in this research are the survival of azospirilla in various soil environments, their colonisation of plant roots and their ability to retain ammonia as free-living diazotrophs. Currently, there is interest in improving the nitrogen nutrition of the plant by the transfer of newly fixed bacterial nitrogen, which has both economic and environmental advantages. Sodium motive force from environment to inside the cellĭiazotrophic azospirilla associate with the roots of agronomically important cereals such as wheat. These chemiosmotic parameters may explain both the poor distribution of Azospirillum in acid soils and their requirement for sodium in alkaline environments. We propose that a sodium motive force can be generated and utilised for metabolic processes in A. brasilense motility was sensitive to amiloride and benzamil, inhibitors of Na +-driven flagellar motors. Intracellular sodium is kept very low relative to the medium, generating a large sodium motive force of about −180 mV at pH 7. These results prompted a study of the sodium motive force. This proton motive force appears to be insufficient to drive metabolic processes such as cell growth and flagellar rotation in neutral and alkaline media. The calculated proton motive force was maximal at −220 mV in pH 5.0 medium, decreasing to zero at pH 8.8. Internal pH was also well regulated at about 7.4 from pH 6–8. It maintained a stable but relatively low membrane potential (ΔΨ) of about −85 mV in conditions typical of aerated soil solutions. ![]() Some biophysical features of the diazotroph Azospirillum brasilense Sp7-S were studied. ![]()
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