Abstract:

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% CaCO₃ 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.

Key words: D-1,2,4-butanetriol, biosynthesis, mixed carbon source, optimization of culture conditions