Soluble Nitrogenase from Vegetative Cells of the Blue-Green Alga Anabaena cylindrica

Abstract

REPORTS of nitrogen fixation by blue-green algal species have, in the main, been restricted to members of the orders Nostocales and Stigonematales1. Unless they are grown in the presence of large concentrations of free ammonium ions, all the species produce characteristic types of cells called heterocysts. The correlation between the ability of a species to fix nitrogen and the possession of heterocysts has led to the suggestion that the heterocyst is the site of nitrogen fixation in blue-green algae2. © 1970 Nature Publishing Group.