title: Deletion of odhA or pyc improves production of γ-aminobutyric acid and its precursor L-glutamate in recombinant Corynebacterium glutamicum.
abstract: OBJECTIVE
  To enhance γ-aminobutyric acid (GABA) production in recombinant Corynebacterium glutamicum, metabolic engineering strategies were used to improve the supply of the GABA precursor, L-glutamate.
  
  
  RESULTS
  C. glutamicum ATCC13032 co-expressing two glutamate decarboxylase genes (gadB1 and gadB2) was constructed in a previous study Shi et al. (J Ind Microbiol Biotechnol 40:1285-1296, 2013) to synthesize GABA from endogenous L-glutamate. To improve its L-glutamate supply, new strains were constructed here. First, the odhA and pyc genes were deleted separately. Then, a gadB1-gadB2 co-expression plasmid was transferred into ΔodhA, Δpyc, and ATCC13032, resulting in recombinant strains SNW201, SNW202, and SNW200, respectively. After fermenting for 72 h, GABA production increased to 29.5 ± 1.1 and 24.9 ± 0.7 g/l in SNW201 and SNW202, respectively, which was significantly higher than that in SNW200 (19.4 ± 2.6 g/l). The GABA conversion ratios of SNW201 and SNW202 reached 0.98 and 0.96 mol/mol, respectively.
  
  
  CONCLUSIONS
  The recombinant strains SNW201 and SNW202 can be used as candidates for GABA production.
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China, flyingwangnan@126.com.
authors: Nannan
authors: N
authors: Wang
authors: Yalan
authors: Y
authors: Ni
authors: Feng
authors: F
authors: Shi
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D048230:Corynebacterium glutamicum / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D055786:Gene Knockout Techniques; D005968:Glutamate Decarboxylase / Q000235:genetics; D018698:Glutamic Acid / Q000378:metabolism*; D060847:Metabolic Engineering; D011994:Recombinant Proteins / Q000235:genetics; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase