Strategies for Enhancing Microbial Production of 2′-Fucosyllactose, the Most Abundant Human Milk Oligosaccharide
Yuanlin Liu, Yingying Zhu, Hao Wang, Li Wan, Wenli Zhang, Wanmeng Mu
Abstract
Human milk oligosaccharides (HMOs), a group of structurally diverse unconjugated glycans in breast milk, act as important prebiotics and have plenty of unique health effects for growing infants. 2′-Fucosyllactose (2′-FL) is the most abundant HMO, accounting for approximately 30%, among approximately 200 identified HMOs with different structures. 2′-FL can be enzymatically produced by α1,2-fucosyltransferase, using GDP-l-fucose as donor and lactose as acceptor. Metabolic engineering strategies have been widely used for enhancement of GDP-l-fucose supply and microbial production of 2′-FL with high productivity. GDP-l-fucose supply can be enhanced by two main pathways, including de novo and salvage pathways. 2′-FL-producing α1,2-fucosyltransferases have widely been identified from various microorganisms. Metabolic pathways for 2′-FL synthesis can be basically constructed by enhancing GDP-l-fucose supply and introducing α1,2-fucosyltransferase. Various strategies have been attempted to enhance 2′-FL production, such as acceptor enhancement, donor enhancement, and improvement of the functional expression of α1,2-fucosyltransferase. In this review, current progress in GDP-l-fucose synthesis and bacterial α1,2-fucosyltransferases is described in detail, various metabolic engineering strategies for enhancing 2′-FL production are comprehensively reviewed, and future research focuses in biotechnological production of 2′-FL are suggested.