Glycerol enhanced simultaneous selenite bioremediation and astaxanthin biosynthesis in Haematococcus lacustris

Selenium (Se) is an essential trace element with nutritional and functional significance; however, elevated concentrations of inorganic Se, particularly selenite, can cause toxicity in aquatic systems. Haematococcus lacustris, a microalga renowned for its production of astaxanthin, offers a dual approach for Se biotransformation and the synthesis of bioactive compounds. This study explores the influence of glycerol-driven biotransformation on inorganic Se uptake, selenium biotransformation, and astaxanthin accumulation. Our results indicate that glycerol supplementation significantly enhances Se bioaccumulation and facilitates its conversion from inorganic into organic Se compounds with reduced toxicity. Concurrently, astaxanthin synthesis is markedly increased, driven by synergistic interactions between Se stress and metabolic adjustments under the treatment of glycerol. Molecular analyses further reveal the co-regulation of metabolic pathways that underpin Se biotransformation and carotenoid biosynthesis. These findings highlight the potential of H. lacustris for developing Se-enriched functional foods and supplements while advancing sustainable biorefinery strategies, offering promising applications in environmental remediation and resource recovery.