Ammonium assimilation in Azospirillum brasilense under saline stress

Azospirillum brasilense growth was reduced to 66% by 300 mM NaCl, at 24 h of culture, reaching control values at 48 h. A. brasilense responded to saline stress elevating the intracellular concentration of glutamate at 24 h, and of K+ at 48 h. These results imply that saline stress affects several cellular functions of A. brasilense. The bacteria manifest saline tolerance under these experimental conditions and one of the osmoadaptation strategies included the accumulation of glutamate. This investigation was carried out to determine the role of the ammonium assimilation enzymes in contributing to saline tolerance. The results obtained showed that the major pathway for ammonium assimilation in A. brasilense was the glutamine synthetase/NADPH-glutamate synthase (GOGAT) route.