Optimizing pH and Light for Enhanced Carotenoid Synthesis and Antioxidant Properties in Sub‐Aerial Cyanobacteria

Carotenoid, natural pigments, synthesized by plants and microbes are now much favored in global markets due to the awareness of their putative health benefits, and a wide array of commercial applications. There is a diversity of natural and synthetic carotenoid, but only a few of them are commercially produced, including carotenes (β-carotene and lycopene) and xanthophylls (astaxanthin, canthaxanthin, lutein, zeaxanthin, and capsanthin). However, for commercial production, plants and algae are more favored than cyanobacteria because of their much less carotenoid synthesis than land plants; although they are well known for producing commercially important carotenoid. But with advances in optimization of their carotenoid production, cyanobacteria can be used as a potential source of carotenoid production in the future allowing us to exploit its various applications. Hence, this study investigated the effects of pH and light conditions on carotenoid production in the sub-aerial cyanobacterium Desertifilum dzianense ON358232.1. The results revealed that the highest carotenoid synthesis occurred under alkaline conditions (pH 9) and red-light exposure, significantly increasing compared to the control (pH 7.2, white light). UV-Vis and FTIR analyses confirmed the presence of β-carotene as the primary carotenoid, demonstrating strong antioxidant potential. The study's findings highlight the optimal environmental parameters for enhancing carotenoid yield, which can be applied for industrial and pharmaceutical uses due to their antioxidant properties.