Cultivation strategy to stimulate high carbohydrate content in Spirulina biomass

This study focused on verifying if production of Spirulina biomass with high carbohydrate content is stimulated by reduced supply of nitrogen associated to addition of NaHCO3 or CO2 at different flow rates and times of injection. For this purpose, addition of 0.25 g L-1 of NaNO3 allowed Spirulina to accumulate up to 49.3% (w w(-1)) of carbohydrates with the highest amount of CO2 (0.3 vvm injected for 5 min). This value reached 59.1% (w w(-1)) when NaHCO3 was the carbon source. Meanwhile, biomass concentration achieved 0.81 and 0.97 g L-1, respectively. In contrast, protein content was inversely proportional to carbohydrate accumulation in the experiments. Thus, this study represents an important step to define cultivation conditions to enhance carbohydrate content in Spirulina. The carbohydrate-rich biomass could be further fermented to produce bioethanol.