Search For Bacterial Alpha 1,2-Fucosyltransferasesfor Whole-Cell Biosynthesis Of 2 '-Fucosyllactose In Recombinant Escherichia Coli

2'-Fucosyllactose (2'-FL) is the most abundant human milk oligosaccharide and is important for infant nutrition and health. Because 2'-FL has potential as a functional ingredient in advanced infant formula and as a prebiotic in various foods, a cost-effective method for 2'-FL production is desirable. alpha 1,2-Fucosyltransferase (alpha 1,2-FT) is one of the key enzymes enabling the microbial biosynthesis of this complex sugar. However, the alpha 1,2-FTs reported so far for the whole-cell biosynthesis of 2'-FL originate from pathogens, posing a potential hurdle for approval as a food production method depending on countries. In this study, 10 alpha 1,2-FT genes from bacteria of biosafety level one were identified, and the main features of the deduced amino acid sequences were characterized. Four codon-optimized alpha 1,2-FT genes were synthesized and introduced into Escherichia coil Delta L M15 strain containing the plasmid pBCGW encoding guanosine 5'-diphosphate-L-fucose biosynthetic enzymes. Among the four genes, 2'-FL was produced only by the alpha 1,2-FT from Thermosynechococcus elongates (Te2FT). Bifidobacterium thermacidophilum alpha 1,2-FT (Bt2FT) showed high expression but was not active in E. coli Delta L M15. The other two alpha 1,2-FTs were not expressed to a detectable level. During batch flask fermentation of Te2FT-expressing E. coli Delta L M15 cells, 0.49 g/L 2'-FL was obtained after 72 h of induction. This is comparable to the values previously reported for alpha 1,2-FTs from Helicobacter pylori and Bacteroides fragilis.