Gyurján, I.

Nghia, N.H.

Stefanovits, P.

Turtóczky, I.

Nitrogen-fixing Azotobacter species were mixed with different strains of unicellular eukaryotic green alga, Chlamydomonas reinhardtii and the mixed cultures were maintained on nitrogen and carbohydrate free medium for over three years. The associated symbioses retained their green colour and grew sufficiently. The chlorophyll content and the photosynthetic 02-evolution of the symbioses showed that they were capable of photosynthesis. Ethylene production of mixed cultures also showed that Azotobacters could fix atmospheric nitrogen in the associative symbioses. Glutamine synthetase activity characteristic for algae was found high in symbioses. In the case of diaphorase and isocitrate dehydrogenase, an enzyme with higher mobility also exists, which was not found in both algae and bacteria. The electron micrographs showed that bacteria localized near the surface of algal cells and in the space between cells and both the bacterial and algal cells could grow and divide in the forced associations.

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