中文摘要：

研究了水/离子液体两相体系中重组毕赤酵母Pichia pastoris GS115（r-PGUS-P）全细胞转化甘草酸（GL）生成单葡萄糖醛酸基甘草次酸（GAMG）的反应。确定最适反应体系为离子液体[BMIM]PF6/水（2∶8,体积比）,最适缓冲液pH、反应温度、底物浓度和细胞加入量分别为5.4、45℃、6.0mmol.L-1和8.0g.L-1。在此条件下反应58h,产物GAMG得率和化学键选择性分别为69.6%和67.2%,与纯水相反应体系相比,分别提高了12.4%和12.61%。离子液体循环使用7次后,回收利用率为93.47%。产物GAMG和副产物甘草次酸（GA）在此两相体系中得到有效分离,为后续产物分离带来便利。

英文摘要：

Glycyrrhizin （GL）, the biologically active compounds of liquorice, can be hydrolysed to glycyrrhetic acid 3-O-mono-β-D-glucuronide （GAMG） by whole cells containing β-D-glucuronidase. GAMG is widely used in the pharmaceutical and food industries due to its stronger physiological functions, higher biological activity, more favorable sweetness, and lower caloric value as compared with GL. The recombinant Pichia pastoris （r-PGUS-P） designated in this work expressing β-D-glucuronidase, was used as a whole-cell biocatalyst catalyzing GL to GAMG in non-aqueous solvents systems. The results showed that r-PGUS-P gave the highest yield of GAMG in 1-butyl-3-methylimidazolium hexafluorophosphate （ [BMIM] PF6 ）/water （2 ： 8, vol） biphasic system. The optimal conditions of this reaction were determined as follows： optimum pH, substrate concentration, temperature and cell content were 5.4, 6.0 mmol- L 1, 45℃, and 8.0 g . L-1, respectively. Under these optimized conditions, 69.6% yield of GAMG and 67.2% of the chemical bond selectivity was achieved after 58 h reaction time, increase by 12.4% and 12.61%, respectively against aqueous phase. Simultaneously, the ionic liquid [BMIM]PF6 also remained at higher recovery percentage of about 93.47% during repeated use for Especially, product GAMG and byproduct glycyrrhetinic acid （GA） got separated automatically that brought convenience for the separation and purification of GAMG. reaction biphasie cycles. system