TEMPERATURE AS AN IMPORTANT FACTOR AFFECTING PRODUCTIVITY AND NIGHT BIOMASS LOSS IN SPIRULINA-PLATENSIS GROWN OUTDOORS IN TUBULAR PHOTOBIOREACTORS

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-degrees-C was superior by 23% to that observed in another culture grown at 25-degrees-C. The rates of night biomass loss were higher in the culture grown at 25-degrees-C (average 7.6% of dry weight) than in the one grown at 35-degrees-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-degrees-C. The excess of carbohydrate synthesized during the day was only partially utilized for night protein synthesis.