Thermal Cycling Cascade Biocatalysis of myo-Inositol Synthesis from Sucrose

myo-Inositol belongs to the vitamin B group (vitamin B8) and is widely used in the drug, cosmetic, and food and feed industries. It is produced by acid hydrolysis of phytate, but this method suffers from costly feedstock and serious phosphorus pollution. Here a four-enzyme pathway containing thermophilic sucrose phosphorylase, phosphoglucomutase, inositol 1-phosphate synthase, and inositol monophosphatase was designed to convert sucrose to inositol and fructose. To enable the use of enzymes with different optimal temperatures and thermostabilities, we developed a thermal cycling cascade biocatalysis that can selectively add less-thermostable sucrose phosphorylase immobilized on cellulose-containing magnetic nanoparticles into the cold enzyme cocktail or remove it from the hot enzyme cocktail by using a magnetic field (ON/OFF) switch. A series of exergonic reactions push the overall reaction forward, resulting in a high product molar yield (0.98 mol of inositol/mol of sucrose). This cascade biocatalysis platform could open a door to the large-scale production of less-costly inositol and upgrade sucrose to a value-added nutraceutical and functional sweetener.