초록
<P><I>Lactobacillus plantarum</I> CCTCC M209102 efficiently produces γ-aminobutyric acid (GABA) from <SMALL>L</SMALL>-glutamate, in which glutamate decarboxylase and pyridoxal kinase are involved in the transformation. Pyridoxal kinase catalyzes ATP-dependent phosphorylation of pyridoxal to produce pyridoxal-5′-phosphate, which is the cofactor required for glutamate decarboxylase to biotransform GABA from <SMALL>L</SMALL>-glutamate. <I>Corynebacterium glutamicum</I> G01 is a good producer of <SMALL>L</SMALL>-glutamate from glucose. However, it cannot yield GABA from <SMALL>L</SMALL>-glutamate due to the absence of glutamate decarboxylase and pyridoxal kinase. In this work, to realize the efficient one-step preparation of GABA from glucose without exogenous pyridoxal-5′-phosphate, the metabolic module from <SMALL>L</SMALL>-glutamate to GABA based on glutamate decarboxylase and pyridoxal kinase in <I>L. plantarum</I> was grafted into <I>C. glutamicum</I>. To further improve the GABA production, the pathways to by-product pools of <SMALL>L</SMALL>-arginine, <SMALL>L</SMALL>-proline and <SMALL>L</SMALL>-lysine were blocked using the insertional mutation technique. The engineered <I>C. glutamicum</I> APLGGP carrying <I>arg</I>B::<I>tacgad</I>, <I>pro</I>B::<I>tacgad</I> and <I>dapA</I>::<I>tacplk</I> could efficiently convert glucose into GABA in one-step without an exogenous co-factor. In fed-batch cultures, the recombinant <I>C. glutamicum</I> APLGGP produced 70.6 g L<SUP>−1</SUP> GABA at 30 °C and 70 h through a two-stage pH control strategy. To our knowledge, this is the highest reported GABA production using glucose as a substrate, and this designed <I>C. glutamicum</I> should be an excellent candidate for producing GABA on an industrial scale. This work is expected to pave the way to redesign the bioreactor for efficient one-step biosynthesis of GABA from glucose without an exogenous co-factor.</P><BR><BR><P>Graphic Abstract</P><P>Efficient one-step production of γ-aminobutyric acid from glucose without an exogenous cofactor pyridoxal-5′-phosphate was realized by the designed <I>Corynebacterium glutamicum</I>.<BR><IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4gc00607k'><BR></P>