Temperature as an important factor affecting productivity and night biomass loss in Spirulina platensis grown outdoors in tubular photobioreactors

Abstract

Outdoor experiments using tubular photobioreactors have shown that in summer the average net productivity of a Spirulina platensis culture grown at the optimal temperature of 35°C was superior by 23% to that observed in another culture grown at 25°C. The rates of night biomass loss were higher in the culture grown at 25°C (average 7·6% of dry weight) than in the one grown at 35°C (average 5% of dry weight). We found that the night biomass loss was dependent on the temperature and light irradiance at which the cells were grown, since these factors influence the biomass composition. A net increase in carbohydrate synthesis was observed when the cells were grown under high light irradiance or at the suboptimal temperature of 25°C. The excess of carbohydrate synthesized during the day was only partially utilized for night protein synthesis.