Abscisic acid and its synthetic analog in relation to growth and nitrogenase activity of Azotobacter chroococcum and Nostoc muscorum.

The plant hormone abscisic acid as well as its synthetic analog LAB 173711 significantly increased the nitrogenase activity of the bacterium Azotobacter chroococcum and the cyanobacterium Nostoc muscorum. The effect depended on the concentration of the substances (0.001-10 mg/L) and the age of the cultures. The biomass of the organisms was not significantly influenced.