Application of photosynthetic N2-fixing cyanobacteria to the CELSS program.

The feasibility of using photosynthetic microalgae (cyanobacteria) as a subsystem component for the CELSS program, with particular emphasis on the manipulation of the biomass (protein/carbohydrate) has been addressed. Using factors which retard growth rates, but not photosynthetic electron flux, the partitioning of photosynthetically derived reductant may be dictated towards CO2 fixation (carbohydrate formation) and away from N2 fixation (protein formation). Cold shock treatment of fairly dense cultures markedly increases the glycogen content from 1% to 35% (dry weight), and presents a useful technique to change the protein/carbohydrate ratio of these organisms to a more nutritionally acceptable form.