The construction of an in vitro synthetic enzymatic biosystem that facilitates laminaribiose biosynthesis from maltodextrin and glucose.

Laminaribiose is a reducing glucobiose 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 was designed for the one-pot synthesis of laminaribiose from low-cost maltodextrin and glucose. Through condition optimization, 51 mM laminaribiose was produced from 10 g/L maltodextrin (55.5 mM glucose equivalent) and 90 mM glucose. The product yield based on maltodextrin was 91.9%. To investigate the industrial potential of this in vitro enzymatic biosystem, the production of laminaribiose from high concentrations of substrates was also examined, and 179 mM laminaribiose was produced from 50 g/L 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.