The Construction of an In Vitro Synthetic Enzymatic Biosystem that Facilitates Laminaribiose Biosynthesis from Maltodextrin and Glucose

: Laminaribiose is a reducing disaccharide linked by a β-1,3 glycosidic bond; it is also a precursor for building blocks in the pharmaceutical industry, a powerful germinating agent and antiseptic, as well as a potential prebiotic. In this study, an in vitro enzymatic biosystem composed of α-glucan phosphorylase, laminaribiose phosphorylase, isoamylase, and 4-glucanotransferase is designed for the one-pot synthesis of laminaribiose from low-cost maltodextrin and glucose. Through condition optimization, 51 mM laminaribiose is produced from 10 g L-1 maltodextrin (55.5 mM glucose equivalent) and 90 mM glucose. The product yield based on maltodextrin is 91.9%. To investigate the industrial potential of this in vitro enzymatic biosystem, the production of laminaribiose from high concentrations of substrates is also examined, and 179 mM laminaribiose is produced from 50 g L-1 of maltodextrin and 450 mM glucose. This in vitro enzymatic biosystem comprised of thermophilic enzymes can drastically decrease the manufacturing cost of laminaribiose and provide a green method for the production of other disaccharides using phosphorylases.