Enhancement of phycocyanin and carbohydrate production from Spirulina platensis growing on tofu wastewater by employing mixotrophic cultivation condition

The high carbohydrate content of readily commercialized microalgae, Spirulina platensis, has gained more attention since it could be utilized as a source of bioethanol. However, the high cost of cultivation needs to be pressed to lower the bioethanol price. The purpose of this study was to study the potency of Spirulina platensis growing in tofu wastewater (TWW) as C-phycocyanin (CPC) and carbohydrate feedstock under mixotrophic conditions. S. platensis was cultivated on different TWW fractions and different organic carbon sources. Box-behnken response surface methodology was employed to optimize organic carbon concentration, UV-C irradiation, and FeEDTA addition. Results showed that glucose addition on 15% TWW accelerates carbohydrate and C-PC productivity. Box-behnken RSM revealed that 0.67 g/L glucose, 5 min UV-C irradiation time, and 10 mg/L FeEDTA resulted in high carbohydrate (49.94 mg/L/d) and C-PC (26.93 mg/ L/d) productivity. Interaction of glucose and UV-C irradiation significantly enhances carbohydrate and C-PC productivity.