Natural resources of zeaxanthin are extremely limited. A Chlorella zofingiensis mutant (CZ-bkt1), which could accumulate high amounts of zeaxanthin, was generated and characterized. CZ-bkt1 was achieved by treating the algal cells with a chemical mutagen followed by a color-based colony-screening approach. CZ-bkt1 was found to consist of a dysfunctional carotenoid ketolase, leading to the accumulation of zeaxanthin rather than to its downstream ketocarotenoid astaxanthin. Light irradiation, glucose, NaCl, and nitrogen deficiency all induced CZ-bkt1 to accumulate zeaxanthin. CZ-bkt1 accumulated zeaxanthin up to 7.00 ± 0.82 mg/g when induced by high-light irradiation and nitrogen deficiency and up to 36.79 ± 2.23 mg/L by additional feeding with glucose. Furthermore, in addition to zeaxanthin, CZ-bkt1 also accumulated high amounts of β-carotene (7.18 ± 0.72 mg/g or 34.64 ± 1.39 mg/L) and lutein (13.81 ± 1.23 mg/g or 33.97 ± 2.61 mg/L). CZ-bkt1 is the sole species up to date with the ability to accumulate high amounts of the three carotenoids that are essential for human health.
Keywords: Chlorella zofingiensis; carotenoid; lutein; microalgae; zeaxanthin.