Metal induced inhibition of growth, heterocyst differentiation, carbon fixation and nitrogenase activity of Nostoc muscorum: Interaction with EDTA and calcium

Abstract

The effects of different concentrations of chromium and lead on survival, growth, heterocyst production, carbon fixation and acetylene reduction of Nostoc muscorum have been studied. Approximately 50% of the algae survived at 68.0 and 72.0 μM concentrations of chromium and lead, respectively. Chromium proved to be more toxic than lead because its sublethal concentration inhibited approximately 82% 14CO2 uptake and 64% acetylene reduction; however, the inhibition of these processes by lead was only 15% and 36%, respectively. Toxicity was found to be reversed by calcium but not by EDTA. It is suggested that calcium plays an important role in ameliorating metal toxicity in Nostoc muscorum.