The effect of different light spectra on selenium bioaccumulation by <i>Spirulina platensis</i> cyanobacteria in flat plate photobioreactors

Selenium (Se) plays a crucial role in human health, influencing conditions such as cancer, diabetes, and neurological disorders. With global population growth and unequal nutrient distribution threatening food security, new approaches are needed to meet the nutritional needs of the world. Se is essential for immune function, metabolism, and antioxidant defense, and in regions suffering from food insecurity and malnutrition, selenium-enriched food could offer an affordable solution. <i>Spirulina platensis</i>, microalgae, can bioaccumulate Se from its environment, enhancing its nutritional value. This study explores how different light spectra (red, white, yellow, and blue LEDs) affect Se bioaccumulation in <i>Spirulina</i> when Na₂SeO₃ is added to the culture medium in photobioreactors. The results show that red light made the highest Se bioaccumulation (0.118 mg.L^-1), followed by white, yellow, and blue light. Se addition also increased cell dry weight by 46%, 33%, 22%, and 60%, respectively, compared to photobioreactors without Se, with biomass productivity highest under red light. Furthermore, Se boosted maximum Chl α concentration, improving photosynthetic efficiency. These findings suggest that optimizing light conditions can significantly enhance the nutritional value of <i>Spirulina</i>, offering a potential solution to global hunger by providing a sustainable, selenium-enriched food source.