Production of d-mannose from d-glucose by co-expression of d-glucose isomerase and d-lyxose isomerase in Escherichia coli

BACKGROUNDd-Mannose is not only the epimer of d-glucose at the C-2 position, but also the aldose isomer of d-fructose. Because of its physiological properties and health benefits, d-mannose has attracted public interest. It has been confirmed that d-mannose has broad applications in food, cosmetics, and pharmaceutical industries. According to the Izumoring strategy, d-glucose isomerase (d-GI) and d-lyxose isomerase (d-LI) play important roles in the conversions of d-fructose from d-glucose and of d-mannose from d-fructose respectively. In this study, a one-step enzyme process of d-mannose production from d-glucose has been constructed by co-expression of the d-GI from Acidothermus cellulolyticus and d-LI from Thermosediminibacter oceani in Escherichia coli BL21(DE3) cells. RESULTSThe co-expression system exhibits maximum activity at pH 6.5 and 65 degrees C with Co2+ supplement. It is relatively thermostable at less than 65 degrees C. When the reaction reaches equilibrium, the ratio of d-glucose, d-fructose, and d-mannose is approximately 34 : 49.6 : 16.4. By using this co-expression system, about 60.0 g L-1 d-mannose is obtained from 400 g L-1 d-glucose in 8 h. CONCLUSIONThis co-expression of d-GI and d-LI system provides a novel and efficient approach for d-mannose production. (c) 2018 Society of Chemical Industry