Promising Biomolecules with High Antioxidant Capacity Derived from Cryptophyte Algae Grown under Different Light Conditions

SIMPLE SUMMARY: In recent decades, the demand for natural and sustainable bioproducts has risen markedly. Accordingly, microalgae have received much attention as a promising biological resource with great industrial potential, since the microalgal production of biologically active compounds can be boosted by changing their cultivation conditions. Light is one of the key factors in the photosynthetic process, which directly affects cell division and the production of biochemical compounds. This study investigated the effect of light color and the species-specific capability of cryptophyte algae to produce phycoerythrin, phenolic compounds, and exopolysaccharides. The produced biomolecules were further studied for their antioxidant activity. The results showed that changes in light quality significantly affect the biochemical compositions of cryptophyte algae. Moreover, species-specific responses to changes in light quality were identified. The quantity and quality of derived biomolecules from the studied cryptophytes are remarkable and indicate that cryptophytes could be considered promising candidates for producing natural biochemical products for practical applications in various industry sectors, such as food, pharmacy, and cosmetics. ABSTRACT: The accumulation and production of biochemical compounds in microalgae are influenced by available light quality and algal species-specific features. In this study, four freshwater cryptophyte strains (Cryptomonas ozolinii, C. pyrenoidifera, C. curvata, and C. sp. (CPCC 336)) and one marine strain (Rhodomonas salina) were cultivated under white (control), blue, and green (experimental conditions) lights. Species-specific responses to light quality were detected, i.e., the color of light significantly affected cryptophyte biomass productivity and biochemical compositions, but the optimal light for the highest chemical composition with high antioxidant capacity was different for each algal strain. Overall, the highest phycoerythrin (PE) content (345 mg g(−1) dry weight; DW) was reached by C. pyrenoidifera under green light. The highest phenolic (PC) contents (74, 69, and 66 mg g(−1) DW) were detected in C. curvata under control conditions, in C. pyrenoidifera under green light, and in C. ozolinii under blue light, respectively. The highest exopolysaccharide (EPS) content (452 mg g(−1) DW) was found in C. curvata under the control light. In terms of antioxidant activity, the biochemical compounds from the studied cryptophytes were highly active, with IC(50) -values < 50 µg mL(−1). Thus, in comparison to well-known commercial microalgal species, cryptophytes could be considered a possible candidate for producing beneficial biochemical compounds.