Combining light strategies with recycled medium to enhance the economic feasibility of phycocyanin production with Spirulina platensis

•Indigenous Spirulina platensis shows high potential as a C-phycocyanin producer.•Combining white LED with light-dark frequency enables energy-saving C-PC production.•Using recycled medium with optimal nitrate addition can enhance C-PC production.•The C-PC productivity obtained (101.1 mg/L/d) is higher than most reported values.

C-phycocyanin (C-PC) produced from Spirulina platensis is of great commercial interest due to its healthcare properties. In this study, light sources and light-dark frequency were manipulated to enhance C-PC productivity of S. platensis. Using white LED resulted in higher C-PC production efficiency when compared to using fluorescent lamps and monochromatic LEDs. Proper adjustment of light-dark efficiency further increased C-PC production efficiency with relatively lower power consumption. In addition, using recycled medium in place of fresh medium proved to be an environmental-friendly and economic strategy for C-PC production with S. platensis. Optimal nitrate supplementation was also employed to improve the C-PC productivity. When grown under optimal culture conditions (i.e., light source, white LED; light-dark frequency, 30:30; recycled medium replacement, 50%; nitrate supplement, 45 mM), S. platensis could obtain the highest C-PC content (14.9%) and C-PC productivity (101.1 mg/L/d). This performance appears to be superior to that obtained from most related studies.