High-Yield Synthesis of 2′-Fucosyllactose from Glycerol and Glucose in Engineered Escherichia coli

2 '-Fucosyllactose (2 '-FL) is vital for the growth and development of newborns. In this study, we developed a synthesis pathway for 2 '-FL in Escherichia coli BL21 (DE3). Then, we optimized the solubility of alpha-1,2-fucosyltransferase, thereby enhancing the production yield of 2 '-FL. Based on this finding, we further enhanced the expression of guanosine inosine kinase Gsk and knocked out the isocitrate lyase regulator gene iclR. This strategy reduced the formation of byproduct acetate during the metabolic process and alleviated carbon source overflow effects in the strain, resulting in further improvement of the yield of 2 '-FL. In a 3 L bioreactor, employing fed-batch fermentation with glycerol and glucose as substrates, the engineered strain BWLAI-RSZL exhibited impressive 2 '-FL titers of 121.9 and 111.56 g/L, along with productivity levels of 1.57 and 1.31 g/L/h, respectively. The reported 2 '-FL titers reached a groundbreaking level, irrespective of the carbon source employed (glycerol or glucose), highlighting the significant potential for large-scale industrial synthesis of 2 '-FL.