Improving carbohydrate accumulation in Chlamydomonas debaryana induced by sulfur starvation using response surface methodology

Sodium Bicarbonate (NaHCO3) Increases Growth, Protein and Photosynthetic Pigments Production and Alters Carbohydrate Production of Spirulina platensis

Improving the biochemical status of Spirulina platensis will enhance the functional properties of this microalgae. The present study investigated the effects of adding NaHCO₃ to the culture medium on the growth rate and biochemical composition, particularly the coproduction of proteins, carbohydrates, and photosynthetic pigments of S. platensis. Spirulina platensis was grown in different NaHCO₃ concentrations (0-16 g L^-1). NaHCO₃ positively affected the biomass production. The growth of S. platensis and biochemical compound content increased with an increase in the NaHCO₃ concentration. The microalgae biomass grown on NaHCO₃ also contained higher amounts of protein (64.20 ± 4.18% w w^-1) and photosynthetic pigments (phycocyanin and chlorophyll a, b, and total). Protein productivity was especially enhanced by approximately 6-25% (from 0.006 ± 0.0030 to 0.025 ± 0.0031 mg L^-1 day^-1) with the addition of NaHCO₃ compared to the control. In contrast, the content of carbohydrates and antioxidant compounds (phenolic, polyphenol oxidase, and peroxidase activities) decreased with culture age and an increase in the NaHCO₃ concentration. These results suggest that S. platensis uses NaHCO₃ as a carbon source for photosynthesis, biomass production, and acts as a metabolic energy carrier toward the synthesis of proteins and photosynthetic pigments, which are more energy-consuming metabolites than carbohydrates. The addition of NaHCO₃ to the culture media is a potentially useful strategy toward improving the protein and photosynthetic pigment productivity of S. platensis.