Physiological characterization of the cultured and freshly isolated endosymbionts from different species of Azolla

Freshly separated and cultured symbionts of six species of Azolla—A. microphylla, A. filiculoides, A. caroliniana, A. rubra, A. mexicana, and A. pinnata—were examined for selected physiological attributes including pigments—chlorophyll, phycobiliproteins; macromolecular components—proteins, sugars and selected enzymes involved in N and P metabolism. These were then compared with the observations recorded for free living strains of Anabaena variabilis and Nostoc sp. The amount of chlorophyll a, proteins, sugars and ammonia excreted was observed to be significantly higher in freshly separated symbionts while their cultured counterparts exhibited higher activities of N-assimilation enzymes. The similarity of the symbionts to free living strains with respect to certain attributes and significant variation in others, provides a lot of interesting information on this symbiotic association and underlines the critical role played by host factors in the metabolic capabilities of the symbionts.