Efficient bioconversion of high-concentration d -fructose into d -mannose by a novel N -acyl- d -glucosamine 2-epimerase from Thermobifida halotolerans

The synthesis of mannose is of great value because it is the only glyconutrient used for clinical applications. Here, we performed the enzymatic bioconversion of d -fructose to d -mannose using a recombinant thermostable N -acyl- d -glucosamine 2-epimerase (ThMI) from a Thermobifida halotolerans engineered strain. The enzymatic bioconversion produced 180 g L −1 d -mannose from high-concentration d -fructose (500 g L −1 ) in 1 h by recombinant ThMI, resulting in a maximum bioconversion ratio of 35.8%. The recombinant resting cells at a density of 10 OD 600 produced 157 g L −1 d -mannose from 500 g L −1 d -fructose in 1 h. These results suggest that the novel biocatalyst system developed in this study can be applied for large-scale industrial production of d -mannose.