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

Abstract

AbstractBackgroundDunaliellaalgae, such asDunaliella salinarich in β-carotene andDunaliella bardawilis rich in lutein and α-carotene, have been used in aquaculture, supplements, cosmetics and feed industries. The genusDunaliellais 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 genusDunaliella. Biomass of ZP-1 in RAM medium is up to 2.45 g/L, showing an advantage over the commonDunaliellaalgae 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 asturn yellow dunaliella 4(tyd4). The mutanttyd4displayed an increased lutein productivity by 28.55% and an increased zeaxanthin productivity by 22.19%. Biomass oftyd4was promoted by 17.40% through continuous culture under red light. Application of exogenous 1.0 µM melatonin on the mutanttyd4lead to increased cell density and improved biomass. Conclusions The results together support that EMS mutagenesis was an effective breeding approach for improvement ofDunaliellasp. ZP-1, which was a high-biomass microalgae exhibiting potential to some extent overcome the bottleneck of low biomass of current commercialDunaliellastrains. The mutanttyd4had 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.