High-Level Production of <scp>l</scp>-Fucose by Plasmid-Free or Antibiotic-Independent Metabolically Engineered <i>Escherichia coli</i> Strains
Jiawei Meng, Yingying Zhu, Zhen Lu, Wenli Zhang, Tao Zhang, Wanmeng Mu
Abstract
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.