Overexpression glucose dehydrogenase can promote the growth of recombinant Escherichia coli

The genes encoding glucose dehydrogenase(gdh) from Klebsiella pneumoniae and Escherichia coli were amplified by polymerase chain reaction(PCR). Subsequently,the corresponding expression vectors p ET-28a-KPgdh and p ET-28a-ECgdh were constructed and cloned into E. coli BL21,resulting in two recombinant strains E. coli(p ET-28a-KPgdh) and E. coli(p ET-28a-ECgdh). SDS-PAGE analysis showed the high level expression of both KPgdh and ECgdh upon IPTG induction. Compared with the control strain E. coli(p ET-28a)which harbored an empty vector,the recombinant strains E. coli(p ET-28a-KPgdh) and E. coli(p ET-28a-ECgdh) consumed more glucose,and the gdh activity toward glucose increased by 8.5-and 12-fold,respectively. If plasmid burden was not counted,overall these results indicated that gdh overexpression facilitated cell growth.