Factors influencing protein synthesis in Spirulina platensis in outdoor culture

Outdoor experiments using photobioreactors have shown that the protein synthesis in Spirulina platensis can be influenced by environmental factors like light intensity, oxygen concentration in the culture, and temperature. (i) It was observed that in Spirulina platensis cultures having a low cellular concentration, the nitrate uptake was completely suppressed when the light intensity reached about 800 W/m2. During the night, the nitrate uptake resumed so that the carbohydrates stored during the day were used for the biosynthesis of protein and other cell constituents. (ii) The biomass produced in long tubular circuits in which the oxygen concentration can reach values over 0.7 atm, had a lower protein content than biomass produced in shorter ones. (iii) Temperature also influenced the protein content of Spirulina biomass: the culture grown at a constant temperature of 25 °C had a lower protein content that one grown at 35 °C.