Stickstoff-Ausscheidung durch N 2-fixierende Blaualgen, III / Nitrogen Excretion by Nitrogen Fixing Blue-green Algae, III : Verwertung des ausgeschiedenen Stickstoffs durch Grünalgen / Utilization of the Excreted Nitrogen by Green Algae

The total combined nitrogen (850 //mol N/1) excreted by the nitrogen fixing blue-green alga, A nabaena cylin drica, during growth in an artificial nutrient medium, was subsequently utilized to a different degree by various green algae. Two species of filamentous green algae, Chlorhormidium spec, (strain I) and Chlorhorm idium spec, (strain II), proved to be most suitable: When grown in the above nitrogen-enriched medium after removal of A nabaena cylindrica, they lowered the nitrogen level in the medium from 850 to 460 - 600//mol N/1 within 29 days. When another nitrogen fixing blue-green alga, Anabaena solitaria, was grown under unsterile conditions in mixtures of freshwater and seawater with trace elements (Fe, Mn, and Mo) added, nitrogen levels of 1000 - 1060 //mol N/1 were obtained. These levels were subsequently lowered to 530 - 570 //mol N/1 by the two species of Chlorhorm idium . Under appropriate growth conditions, the combined nitrogen excreted by Anabaena solitaria can possibly be utilized as a nitrogen source for green algae