The feasibility of mass cultivation of Porphyridium

The feasibility of growing Porphyridium biomass outdoors was investigated. Laboratory studies indicated that although the optimum temperature for growth is 25°C no damage to the photosynthetic activity can be detected after exposure of the organism to higher temperatures, up to 35°C. Also, high O₂ evolution activity was observed even at relatively high cell concentrations. No inhibition of O₂ evolution was detected at high light intensity, i.e. 2000 μE m^-2 s^-1. In cultures grown outdoors an output rate of up to 22 g dry wt m^-2 day^-1 was obtained for several weeks. The biomass contained, on a dry weight basis, up to 40% polysaccharides and about 1·5% arachidonic acid. The cultures were maintained essentially monoalgal for over 3 months. The biomass can be readily removed from the medium by autoflocculation.