重组地衣芽胞杆菌全细胞催化合成淫羊藿次苷D2

Synthesis of icariside D2 by whole-cell biocatalysis of recombinant Bacillus licheniformis

分别利用糖基转移酶YjiC、YdhE、YojK的过表达载体电转化地衣芽胞杆菌DW2,相应获得重组菌株ID02、ID03和ID04,并借助pgcA和gtaB基因强化菌株ID02中的UDP-葡萄糖代谢途径来获得重组菌株ID05,研究了基因改造及发酵条件对淫羊藿次苷D2产量的影响。结果表明,YjiC、YdhE、YojK均可糖基化酪醇合成淫羊藿次苷D2,且三者酶催化活性依次减弱;强化UDP-葡萄糖代谢途径并不能促进淫羊藿次苷D2的合成;经正交试验优化后的发酵培养基中NH 4Cl为3 g/L、磷酸缓冲盐为75 mmol/L,菌株ID02在此条件下发酵48 h时相应的淫羊藿次苷D2的产量可达到4010 mg/L。

Electrotransformation was performed on Bacillus Licheniformis DW2 to obtain recombinant strain ID02,ID03 and ID04 by using overexpression vectors of glycosyltransferase YjiC,YdhE and YojK,respectively,and the recombinant strain ID05 was formed through enhancing the metabolic pathway of UDP-glucose in the strain ID02 with pgcA and gtaB genes.Then the influences of genetic modifications and fermentation conditions on the production of icariside D2 were investigated.The results show that YjiC,YhdE and YojK all can convert tyrosol to icariside D2 via glycosylation,and YjiC exhibits the highest enzymatic activity,followed by YdhE and YojK.In addition,the enhancement of the metabolic pathway for UDP-glucose does not further increase icariside D2 production.Under the optimum fermentation medium conditions(NH 4Cl at 3 g/L and phosphate buffered saline at 75 mmol/L)obtained by orthogonal tests,the production of icarisde D2 can reach 4010 mg/L when the strain ID02 is fermented for 48 h.