Enhanced Production of Astaxanthin without Decrease of DHA Content inAurantiochytrium limacinumby Overexpressing Multifunctional Carotenoid Synthase Gene

Aurantiochytrium limacinumproduces both docosahexaenoic acid (DHA) and astaxanthin, respectively. Organisms that produce these industrially important materials more efficiently than microalgae are currently needed. In this study, we overexpressed a putative homolog ofCarS, which is involved in synthesizing the astaxanthin precursor, beta-carotene, inA. limacinumto increase carotenoid synthesis with the goal of obtaining strains that produce large amounts of both DHA and carotenoids. AlCarS transformants #1 and #18 produced significantly increased amounts of astaxanthin as assessed according to culture (up to 5.8-fold) and optical density (up to 9.3-fold). The improved astaxanthin production of these strains did not affect their DHA productivity. Additionally, theirCarSexpression levels were higher than those of the wild-type strain, suggesting thatCarSoverexpression enhanced beta-carotene production, which in turn improved astaxanthin productivity. Although cell yields were slightly decreased, these features will be valuable in health food, medical care, and animal feed fields.

Automated summary

The study successfully increased astaxanthin production in Aurantiochytrium limacinum without affecting DHA productivity by overexpressing the CarS gene. The astaxanthin yield was increased by 5.8 to 9.3 times, showing potential value in the fields of food, healthcare, and animal feed.