Engineering strategies for simultaneous enhancement of C-phycocyanin production and CO₂ fixation with Spirulina platensis

Spirulina platensis produces nutraceutical product C-phycocyanin (C-PC) and simultaneously mitigates CO₂ emissions during its growth. Using a designed flat-type photobioreactor, the S. platensis biomass production was markedly enhanced, leading to a CO₂ removal rate and a biomass concentration of 0.23g/L/d and 2.25g/L, respectively. The cell growth, CO₂ fixation rate and C-PC production of S. platensis were investigated when it was cultivated under different irradiation conditions. As the light intensity increased from 100 to 700μmol/m²/s, the overall biomass productivity, CO₂ consumption rate and maximal C-PC productivity increased significantly to 0.74, 1.53 and 0.11g/L/d, respectively. After determining the suitable light intensity, the nitrogen concentration was also adjusted to further enhance the performance of CO₂ fixation and C-PC production. The results show that with an optimal nitrogen concentration of 0.045M, the CO₂ consumption rate and maximal C-PC productivity were further increased to 1.58 and 0.13g/L/d, respectively.