The Azolla-Anabaena azollae Relationship

Abstract

The heterocystous blue-green alga, Anabaena azollae, was isolated from the leaf cavities of the water fern, Azolla caroliniana, where it occurs as an endophyte. The isolated alga was capable of light dependent CO2 fixation and acetylene reduction. Aerobic dark acetylene reduction occurred and was dependent upon endogenous substrates.