Abstract
Deinoxanthin, a xanthophyll derived from Deinococcus species, is a unique organic compound that provides greater antioxidant effects compared to other carotenoids due to its superior scavenging activity against singlet oxygen and hydrogen peroxide. Therefore, it has attracted significant attention as a next-generation organic compound that has great potential as a natural ingredient in a food supplements. Although the microbial identification of deinoxanthin has been identified, mass production has not yet been achieved. Here, we report, for the first time, the development of an engineered extremophilic microorganism, Deinococcus radiodurans strain R1, that is capable of producing deinoxanthin through rational metabolic engineering and process optimization. The genes crtB and dxs were first introduced into the genome to reinforce the metabolic flux towards deinoxanthin. The optimal temperature was then identified through a comparative analysis of the mRNA expression of the two genes, while the carbon source was further optimized to increase deinoxanthin production. The final engineered D. radiodurans strain R1 was able to produce 394 ± 17.6 mg/L (102 ± 11.1 mg/g DCW) of deinoxanthin with a yield of 40.4 ± 1.2 mg/g sucrose and a productivity of 8.4 ± 0.2 mg/L/h from 10 g/L of sucrose. The final engineered strain and the strategies developed in the present study can act as the foundation for the industrial application of extremophilic microorganisms.
Highlights
Xanthophylls are oxygenated carotenoids that have received significant interest as an ingredient in natural foods due to their association with beauty and health
According to a previous report, deinoxanthin biosynthesis is initiated through the methylerythritol 4-phosphate (MEP) pathway, and the carotenoid γ-carotene is utilized as a core backbone at the end of the synthesis process
Unique structural features that lead to superior antioxidant performance are created via enzymatic modifications such as hydroxylation, desaturation, and ketolation mediated by 1,2-hydratase (CruF), carotenoid 30,40 - desaturase (CrtD), carotenoid ketolase (CrtO), and carotene 2-βhydroxlyase (DR2473) (Figure S1) [22]
Summary
Xanthophylls are oxygenated carotenoids that have received significant interest as an ingredient in natural foods due to their association with beauty and health. Xanthophylls have distinctive structural features such as terminal hydroxy groups, ketones, aldehyde, and epoxy groups that provide superior radical scavenging activity compared with carotenes such as β-carotene and lycopene [1,2,3]. Over the last few decades, significant research progress has been made on the microbial production of xanthophylls using microalgae, yeast, and other microorganisms. The biosynthetic pathway for astaxanthin, zeaxanthin, and lutein, which are widely used as dietary supplements, has been discovered in various microorganisms [4,5,6]. (3R)-saproxanthin and (3R,20 S)myxol, which enhance lipid peroxidation activity compared with β-carotene, were isolated from the marine bacterial strains 04OKA-13-27 and YM6-073, respectively [7]. Another study reported the isolation of siphonaxanthin, which is considered a promising anti-cancer compound, from green algae within the order Siphonales [8]
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