l-Fucose is an important monosaccharide unit that exists in various biomasses, especially in microalgae. Microbial l-fucose using metabolically engineered strains has attracted attention due to its high yield and industrial feasibility. Previously, we engineered Escherichia coli MG1655 to efficiently produce 2′-fucosyllactose by genomic integration. Herein, this plasmid-free strain was further engineered to produce l-fucose by integrating a specific α-l-fucosidase gene and deleting the l-fucose degradation pathway. Its effectiveness of l-fucose biosynthesis by plasmid-free and inducer-free fermentation was demonstrated by both shake-flask and fed-batch cultivation with titers of 2.74 and 21.15 g/L, respectively. The precursor GDP-l-fucose supply was strengthened to obviously enhance l-fucose biosynthesis by introducing a single plasmid expressing four pathway genes. The hok/sok system was introduced to promote the plasmid stabilization without antibiotic. The final engineered strain efficiently could produce l-fucose without antibiotics, with titers of 6.83 and 35.68 g/L by shake-flask and fed-cultivation cultivation, respectively.

中文翻译：

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通过无质粒或不依赖抗生素的代谢工程大肠杆菌菌株高水平生产 L-岩藻糖

l-岩藻糖是一种重要的单糖单元，存在于各种生物质中，尤其是微藻中。使用代谢工程菌株生产的微生物L-岩藻糖因其高产率和工业可行性而引起人们的关注。此前，我们改造了大肠杆菌MG1655，通过基因组整合高效生产 2′-岩藻糖基乳糖。在此，该无质粒菌株被进一步改造，通过整合特定的α - l-岩藻糖苷酶基因并删除l-岩藻糖降解途径来生产l-岩藻糖。通过摇瓶和补料分批培养证明了其通过无质粒和无诱导物发酵进行l-岩藻糖生物合成的有效性，效价分别为 2.74 和 21.15 g/L。通过引入表达四个途径基因的单个质粒，加强了前体GDP- l-岩藻糖的供应，从而显着增强了l-岩藻糖的生物合成。引入hok / sok系统以促进质粒稳定，无需抗生素。最终的工程菌株可以在不使用抗生素的情况下高效生产l-岩藻糖，摇瓶培养和流加培养的滴度分别为6.83和35.68 g/L。