Growth performance of Scenedesmus sp. AQUAMEB-57. Ankistrodesmus sp. AQUAMEB-33, and Synechococcaceae AQUAMEB-32 cultivated at different light intensities.

Abstract

Increasing air pollutants significantly contributes to climate change, requiring innovative mitigation strategies. Microalgae provide a promising solution by absorbing CO₂ and pollutants like nitrogen oxides (NO_x), sulfur oxides (SO_x), and ammonia from agricultural and industrial emissions, while also generating biomass for biofuels and animal feed. This study investigated the effects of light intensity on the growth and biochemical composition of Scenedesmus sp. AQUAMEB-57, Ankistrodesmus sp. AQUAMEB-33, and Synechococcaceae AQUAMEB-32 cultivated in photobioreactors under two batch and continuous culture conditions. Scenedesmus sp. reached the highest cell concentration (8 × 10⁶ cells ml^-1) at 200 µmol photons m^-2s^-1, while Ankistrodesmus sp. and Synechococcaceae peaked at 300 µmol photons m^-2s^-1. Dry biomass was highest for all species at 300 µmol photons m^-2s^-1. Scendesmus sp showed the highest protein content (15.6%) at a light intensity of 200 µmol photons m^-2s^-1, Ankistrodesmus sp. (17.2%) at 300 µmol photons m^-2s^-1, and Synechococcaceae (23.5%) at 100 µmol photons m^-2s^-1. Maximum carbohydrate content for Scenedesmus sp., Ankistrodesmus sp., and Synechococcaceae was 56.0%, 20.5%, and 18.4%, respectively, at 300 µmol photons m^-2s^-1. C16/C18 fatty acids significantly increased as light intensity was raised from 100 to 200 µmol photons m^-2s^-1. The findings show that light intensity impacts growth rates and biochemical profiles, varying by species and cultivation mode. Continuous systems yield higher biomass than batch systems, emphasizing the need for optimized strategies to enhance algal productivity. This research enhances understanding of microalgal growth dynamics, offering insights into optimizing conditions for improved biomass yield and supporting sustainable biofuel production and other valuable products.