Enhancement of astaxanthin accumulation using black light in Coelastrum and Monoraphidium isolated from Malaysia

Microalgae are important microorganisms which produce potentially valuable compounds. Astaxanthin, a group of xanthophyll carotenoids, is one of the most powerful antioxidants mainly found in microalgae, yeasts, and crustaceans. Environmental stresses such as intense light, drought, high salinity, nutrient depletion, and high temperature can induce the accumulation of astaxanthin. Thus, this research aims to investigate the effect of black light, also known as long-wave ultraviolet radiation or UV-A, as a stressor on the accumulation of astaxanthin as well as to screen the antioxidant property in two tropical green algal strains isolated from Malaysia, Coelastrum sp. and Monoraphidium sp. SP03. Monoraphidium sp. SP03 showed a higher growth rate (0.66 day(-1)) compared to that of Coelastrum sp. (0.22 day(-1)). Coelastrum sp. showed significantly higher accumulation of astaxanthin in black light (0.999 g mL culture(-1)) compared to that in control condition (0.185 g mL(-1)). Similarly, Monoraphidium sp. SP03 showed higher astaxanthin content in black light (0.476 g mL culture(-1)) compared to that in control condition (0.363 g mL culture(-1)). Coelastrum sp. showed higher scavenging activity (30.19%) when cultured in black light condition, indicating a correlation between the antioxidant activity and accumulation of astaxanthin. In this study, black light was shown to possess great potential to enhance the production of astaxanthin in microalgae.

Automated summary

This research investigates the impact of black light as a stressor on the accumulation of astaxanthin in two tropical green algal strains. The study found that both Coelastrum sp. and Monoraphidium sp. SP03 showed significantly higher levels of astaxanthin accumulation under black light conditions, with Coelastrum sp. exhibiting higher scavenging activity. The results suggest that black light has the potential to enhance the production of astaxanthin in microalgae.