Elevated accumulation of lutein and zeaxanthin in a novel high-biomass strain Dunaliella sp. ZP-1 through EMS mutagenesis

Abstract Background Dunaliella algae, such as Dunaliella salina rich in β-carotene and Dunaliella bardawil is rich in lutein and α-carotene, have been used in aquaculture, supplements, cosmetics and feed industries. The genus Dunaliella is diverse and secretive, so characterization of novel strains and breeding new varieties through mutagenesis technology will promote natural carotenoid bioproduction. Results Salt stress test demonstrated microalgae strain ZP-1 was a halotolerant strain. Morphology observation and phylogeny analysis indicated this unicellular green algae ZP-1 was a member of the genus Dunaliella . Biomass of ZP-1 in RAM medium is up to 2.45 g/L, showing an advantage over the common Dunaliella algae in terms of yield. Furthermore, a screen on ethyl methanesulfonate mutant library generated from this high-biomass strain was conducted to improve natural carotenoid productivity. A mutant strain selected through morphology observation combined with carotenoid quantification by HPLC was nominated as turn yellow dunaliella 4 ( tyd4 ). The mutant tyd4 displayed an increased lutein productivity by 28.55% and an increased zeaxanthin productivity by 22.19%. Biomass of tyd4 was promoted by 17.40% through continuous culture under red light. Application of exogenous 1.0 µM melatonin on the mutant tyd4 lead to increased cell density and improved biomass. Conclusions The results together support that EMS mutagenesis was an effective breeding approach for improvement of Dunaliella sp. ZP-1, which was a high-biomass microalgae exhibiting potential to some extent overcome the bottleneck of low biomass of current commercial Dunaliella strains. The mutant tyd4 had higher contents of both lutein and zeaxanthin, whose yield could be further elevated by red light and melatonin at lab-scale culture. Our study provided new algae resources for scientific research and technical reference to bioproduction of natural carotenoids.