Multi-enzyme systems and recombinant cells for synthesis of valuable saccharides: Advances and perspectives

Saccharides have recently attracted considerable attention because of their biological functions and potential applications in the pharmaceutical, cosmetic and food industries. Over the decades, a large amount of enzymes involved in saccharide synthesis have been discovered and characterised with the aid of available genome sequences. The advancement of metabolic engineering and synthetic biology strategies facilitated the artificial pathway design and construction for production of multiple sugars in vitro and in vivo based on those characterized enzymes. This review presented a panoramic view of enzymes related to saccharide synthesis and gave the detailed information. Furthermore, we provide an extensive overview of the recent advances in the construction of cell-free reaction systems and engineering of microbial cells for the production of natural or unnatural saccharides. In addition, the future trends in the synthesis of sugars with high structural diversity through the combination of multiple pathways are presented and evaluated.