The influence of the form and concentration of inorganic nitrogen supplied on nitrogen uptake by Ankistrodesmus falcatus

Summary

The unicellular green alga Ankistrodesmus falcatus shows preferential uptake of ammonium when grown in media containing both ammonium and nitrate. However, kinetic studies on ammonium and nitrate uptake from the growth medium indicate that simple Michaelis-Menten kinetics do not hold. Uptake resembles the multiphasic system frequently observed in higher plants for a range of inorganic and organic substances^{4, 6}. At least four discontinuous phases are observed when cells are incubated at inorganic nitrogen levels of 0–1.5 mM nitrate or 0–5 mM ammonium, and this has important implications in the use of this organism in the biological treatment of nitrogen loaded effluents.