Developing a Chromochloris zofingiensis Mutant for Enhanced Production of Lutein under CO 2 Aeration.

Microalgae are competitive and commercial sources for health-benefit carotenoids. In this study, a Chromochloris zofingiensis mutant ( Cz-pkg ), which does not shut off its photosystem and stays green upon glucose treatment, was generated and characterized. Cz-pkg was developed by treating the algal cells with a chemical mutagen as N -methyl- N' -nitro- N -nitrosoguanidine and followed by a color-based colony screening approach. Cz-pkg was found to contain a dysfunctional cGMP-dependent protein kinase (PKG). By cultivated with CO 2 aeration under mixotrophy, the mutant accumulated lutein up to 31.93 ± 1.91 mg L -1 with a productivity of 10.57 ± 0.73 mg L -1 day -1 , which were about 2.5- and 8.5-fold of its mother strain. Besides, the lutein content of Cz-pkg could reach 7.73 ± 0.52 mg g -1 of dry weight, which is much higher than that of marigold flower, the most common commercial source of lutein. Transcriptomic analysis revealed that in the mutant Cz-pkg , most of the genes involved in the biosynthesis of lutein and chlorophylls were not down-regulated upon glucose addition, suggesting that PKG may regulate the metabolisms of photosynthetic pigments. This study demonstrated that Cz - pkg could serve as a promising strain for both lutein production and glucose sensing study.