Factorial optimization of upstream process in Spirulina platensis for growth and carotenoid production

The filamentous cyanobacterium Spirulina platensis is well known for its unique blend of nutraceuticals and bio-pigments that can be used in the food, pharmaceutical, and cosmetic industries. In this study, nutritional and environmental parameters for Spirulina platensis were optimized using Response Surface Methodology (RSM), to enhance biomass accumulation and carotenoid production. Six variables viz. nitrate, phosphate, NaCl concentration, light intensity, light duration, and temperature were systematically varied to determine conditions maximizing growth and pigment yield. The optimal growth conditions for the cyanobacterium included culture media (Zarrouk's medium) with 2.57 g L^-1 nitrate, 1.22 g L^-1 phosphate, and 2.37 g L^-1 NaCl followed by incubation at a light intensity of 2295.45 Lux for 17.73 h at a temperature of 26.81 °C, leading to 62.5% increase in growth (OD₆₆₀) compared to the control. Highest carotenoid content (4.50 µg mL⁻¹, 80% above control) was achieved at 1 g L⁻¹ nitrate, 0.5 g L⁻¹ phosphate, and 2.37 g L⁻¹ NaCl, with light at 1977.27 Lux for 19.35 h and 28.03 °C. Model validation showed high composite desirability (0.84-0.91), confirming predictive accuracy. Ultra-performance liquid chromatography identified zeaxanthin, antheraxanthin, β-carotene, and carotenoid esters including zeaxanthin dibutyrate, zeaxanthin dicaprate, and astaxanthin dibutyrate, highlighting the enhanced diversity and commercial value of pigments produced under optimized conditions. These findings demonstrated that targeted modulation of culture parameters can significantly improve both the quantity and quality of carotenoids in Spirulina platensis, supporting its potential as a high-value pigment source for food, nutraceutical, and cosmetic industries.

The online version contains supplementary material available at 10.1007/s13205-025-04545-6.