Morphological and physiological properties of symbiotic cyanobacteria

Abstract

The main morphological and physiological characters of several symbiotic cyanobacterial strains, isolated from different plant—cyanobacteria associations (Anthoceros, Azolla, cycads and Gunnera) were investigated. All the strains showed heterocystous immotile filaments and motile hormogonia, typical of the genus Nostoc. In accordance with their symbiotic origin, all were found capable of photoheterotrophic growth. On the basis of the morphological and physiological properties and the phycobiliprotein content, the isolates from Azolla appeared very close to each other and quite distinct from the other cyanobionts. The latter showed many characteristics in common, such as marked tendency to produce hormogonia, synthesis of C‐phycoerythrin and rather small dimensions of the akinetes. With regard to the cycad cyanobionts, there was no correlation between the properties of the isolates and the host plants. Copyright © 1992, Wiley Blackwell. All rights reserved