Background

Zeaxanthin is a natural xanthophyll carotenoid that is widely produced by plants, algae and microorganisms and plays a critical role in the prevention of age-related eye diseases, such as macular degeneration and cataracts. Zeaxanthin is also used in the food, pharmaceutical and nutraceutical industries because of its strong antioxidant and anti-cancer properties. To date, zeaxanthin has been primarily produced by extraction from natural resources, especially plants, which is costly and environmentally unfriendly. The biosynthesis of zeaxanthin by microorganisms has been reported in lots of works to provide another potential route for zeaxanthin production.

Scope and approach

In this review, we discuss the zeaxanthin biosynthetic pathway, naturally occurring zeaxanthin-accumulating microorganisms containing bacteria and microalgae, the optimization of fermentation conditions using these microorganisms, and zeaxanthin production using microbial cells factory constructed by metabolic engineering. The different metabolic engineering strategies and the zeaxanthin-accumulating level of the reviewed wild and engineered microorganisms are also considered. Furthermore, this work presents perspectives concerning the microbial production of zeaxanthin, especially the trends to construct the metabolically engineered microorganisms for zeaxanthin production.

Key findings and conclusions

To date, all the reported wild zeaxanthin-accumulating microorganisms belong to either bacteria or microalgae, while most of the reported engineering microorganisms for zeaxanthin production are Escherichia coli or yeast. A feasible strategy for zeaxanthin production is the use of metabolic engineering to construct a zeaxanthin-accumulating microbial cells factories followed by the optimization of fermentation with the engineered strain. Besides the simple overexpression of the biosynthesizing genes, the dynamic regulation of the constructed pathway has also been used for zeaxanthin production by metabolic engineering. Construction of better microbial cells factories which produce more zeaxanthin will profit from the breakthrough of the following fields: Introduction of higher plant zeaxanthin biosynthesizing genes into microorganisms; Characterization of novel zeaxanthin pathway genes from the wild microorganisms producing high level of zeaxanthin; Deep investigation of the farnesyl diphosphate formation pathway; Construction of microbial host with weak antioxidative capacity.

中文翻译：

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微生物对玉米黄质的生物技术生产

背景

玉米黄质是一种天然的叶黄素类胡萝卜素，由植物，藻类和微生物广泛产生，在预防与年龄有关的眼部疾病（如黄斑变性和白内障）中起着至关重要的作用。玉米黄质也因其强大的抗氧化剂和抗癌特性而被用于食品，制药和营养保健品行业。迄今为止，玉米黄质主要是通过从自然资源特别是植物中提取而生产的，这既昂贵又对环境不利。在许多工作中已经报道了微生物对玉米黄质的生物合成，以提供另一种潜在的玉米黄质生产途径。

范围和方法

在这篇综述中，我们讨论了玉米黄质的生物合成途径，天然存在的含有细菌和微藻类的玉米黄质累积微生物，使用这些微生物的发酵条件的优化以及使用通过代谢工程建造的微生物细胞工厂生产玉米黄质的方法。还考虑了不同的代谢工程策略和所审查的野生和工程微生物的玉米黄质积累水平。此外，这项工作提出了关于玉米黄质的微生物产生的观点，特别是构建用于玉米黄质产生的代谢工程微生物的趋势。

主要发现和结论

迄今为止，所有报告的野生玉米黄质积累微生物都属于细菌或微藻类，而大多数报告的玉米黄质生产工程微生物是大肠杆菌。或酵母。玉米黄质生产的可行策略是使用代谢工程来构建玉米黄质积聚的微生物细胞工厂，然后使用工程菌株优化发酵。除了生物合成基因的简单过表达以外，构建途径的动态调节也已通过代谢工程用于玉米黄质的生产。建立更好的生产玉米黄质的微生物细胞工厂将得益于以下领域的突破：将更高的植物玉米黄质生物合成基因引入微生物；从产生高水平玉米黄质的野生微生物中鉴定玉米黄质新途径基因；对法呢基二磷酸形成途径的深入研究；