葡萄糖-木糖共利用对重组大肠杆菌合成D-1,2,4-丁三醇的影响

Effects of Glucose-xylose Co-utilization on the Synthesis of D-1,2,4-Butanetriol by Recombinant Escherichia coli

研究共利用葡萄糖、木糖对重组大肠杆菌合成D-1,2,4-丁三醇(BT)的影响,并优化混合底物时重组菌株合成丁三醇的培养条件。通过敲除影响磷酸转移酶系统(PTS)运行的基因,构建共利用葡萄糖-木糖的合成BT重组菌株,考察了mtfA敲除及mlc过表达菌株MJ133k-ΔmtfA-PTMXM的摇瓶培养条件。结果显示:分别敲除基因ptsG、mtfA和pgi,可使菌株能同时利用木糖及葡萄糖并促进BT合成。菌株MJ133k-ΔmtfA-PTMXM合成BT的培养基及培养条件为:采用1.5×LB培养基,加入10 g/L CaCO_(3)以控制pH,发酵温度33℃,装液量为60 mL/250 mL;6 h时分别加入葡萄糖5 g/L及木糖20 g/L,24 h再次加入5 g/L葡萄糖,BT合成量达3.36 g/L,是未修饰菌株培养条件优化前BT合成量的4.15倍。表明葡萄糖、木糖共利用有效促进了重组大肠杆菌合成BT。

The purpose of this study is to investigate the effects of co-utilization of glucose and xylose on D-1,2,4-butanetriol(BT)biosynthesis by recombinant Escherichia coli,and to optimize the culture condition for BT production when glucose and xylose were used as mixed carbon source.By knocking out the genes affecting glucose phosphotransferase system(PTS),a series of BT-synthesized E.coli that could co-utilize a mixture of glucose and xylose were constructed,the shake-flask culture conditions of mtfA knockout and mlc overexpression strain MJ133k-ΔmtfA-PTMXM were optimized.The results showed that the strains with the genes of ptsG,mtfA and pgi deleted respectively used glucose and xylose simultaneously,and BT biosynthesis was improved.The culture conditions of strain MJ133k-ΔmtfA-PTMXM synthesizing BT was as follows:1.5×LB was used as culture medium,in which 1%CaCO_(3) was added to maintain pH stable,culture temperature was kept at 33℃,medium volume of 60 mL was used in 250 mL flask.Twenty gram per liter xylose was added to the medium at 6 h and 5 g/L glucose was added twice at 6 h and 24 h respectively.The yield of BT reached 3.36 g/L,which was 4.15 times higher compared to that by original strain.In conclusion,co-utilization of glucose and xylose effectively improves BT production by the recombinant E.coli.