Effect of temperature on yield and night biomass loss in Spirulina platensis grown outdoors in tubular photobioreactors.

Outdoor experiments carried out in Florence, Italy (latitude 43.8° N, longitude 11.3 ° E), using tubularphotobioreactors have shown that in summer the average net productivity of a Spirulina platensis culturegrown at the optimal temperature of 35 C was superior by 23 % to that observed in a culture grown at25 C. The rates of night biomass loss were higher in the culture grown at 25 C (average 7.6 % of totaldry weight) than in the one grown at 35 C (average 5%). Night biomass loss depended on thetemperature and light irradiance at which the cultures were grown, since these factors influenced thebiomass composition. A net increase in carbohydrate synthesis occurred when the culture was grown ata low biomass concentration under high light irradiance or at the suboptimal temperature of 25 C.Excess carbohydrate synthesized during the day was only partially utilized for night protein synthesis.