The Functional Characterization of the 6-Phosphogluconate Dehydratase Operon in 2-Ketogluconic Acid Industrial Producing Strain JUIM01.

Genus bacteria mainly consume glucose through the Entner-Doudoroff (ED) route due to a lack of a functional Embden-Meyerhof-Parnas (EMP) pathway. In the present study, a 6-phosphogluconate dehydratase () operon in the ED route was well investigated to find its structural characteristics and roles in the regulation of glucose consumption and 2-ketogluconic acid (2KGA) metabolism in the industrial 2KGA-producer JUIM01. The operon contained four structural genes of , , , and , encoding 6-PG dehydratase Edd, glucokinase Glk, response regulatory factor GltR, and histidine kinase GtrS, respectively. A promoter region was observed in the 5'-upstream of the gene, with a transcriptional start site located 129 bp upstream of the gene and in a pseudo-palindromic sequence of 5'-TTGTNACAA-3' specifically binding to the transcription factor HexR. The knockout of the gene showed a remarkably negative effect on cell growth and re-growth using 2KGA as a substrate, beneficial to 2KGA production, with an increase of 8%. The deletion of had no significant effect on the cell growth or glucose metabolism, while showing an adverse impact on the 2KGA production, with a decrease of 5%. The outputs of the present study would provide a theoretical basis for 2KGA-producer improvement with metabolic engineering strategies and the development and optimization of as the chassis cells.