来源于 Dictyoglomus sp. NZ13-RE01 的纤维二糖差向异构酶酶学性质和乳果糖制备研究

To produce lactulose efficiently, the gene encoding cellobiose 2-epimerase (CE) from Dictyoglomus sp. NZ13-RE01 was cloned into pET-28a, resulting the plasmid pET-28a-NZ13 and expressed in E. coli BL21(DE3) . The activity of recombinant NZ13-CE was 0. 53 U / mL after 24 h induction with IPTG in shaking flask, and the highest enzyme activity of 4. 3 U / mL was obtained with high cell density cultivation in 7. 5 L fermenter. NZ13-CE was purified by nickel ion affinity chromatography and biochemically characterized. The molecular mass of NZ13-CE was 45. 5 kDa, the optimal temperature and pH were 80 ℃ and 8. 0, respectively. The activity half-time of NZ13-CE was 181. 5 min at 80 ℃, and the highest conversion rate from lactose to lactulose was 52. 5% . In addition, the final ratio of epilactose only was 9% . The heterologous expression of NZ13-CE in E. coli provided a great potential for the production of lactulose.