title: Enhancement of L-valine production in Bacillus licheniformis by blocking three branched pathways.
abstract: OBJECTIVE
  Bacillus licheniformis WX-02 is used for the production of many valuable chemicals. Here, we have sought to improve L-valine production by blocking the metabolic pathways related to branched-chain amino acids.
  
  
  RESULTS
  The synthesis genes of L-leucine (leuA) and L-isoleucine (ilvA) were deleted to obtain mutant strains. L-Valine yields of WX-02ΔleuA and WX-02ΔilvA reached 33.2 and 21.1 mmol/l, respectively, which are 22 and 14 times higher than the wild-type WX-02 (1.53 mmol/l). After further deletion of L-lactate dehydrogenase gene (ldh) from WX-02ΔleuA, the productivity reached 0.47 mmol/l h, an increase of 19 %.
  
  
  CONCLUSIONS
  We provide a possibility to over-produce L-valine using genetically-modified B. licheniformis using remodeling of the biosynthetic pathway to L-valine.
authors.affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, Wuhan, 430062, People's Republic of China.
authors.forename: Chengwen
authors.initials: C
authors.lastname: Liang
authors.forename: Yanli
authors.initials: Y
authors.lastname: Huo
authors.forename: Gaofu
authors.initials: G
authors.lastname: Qi
authors.forename: Xuetuan
authors.initials: X
authors.lastname: Wei
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.forename: Shouwen
authors.initials: S
authors.lastname: Chen
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000378:metabolism*; D001407:Bacillus / Q000235:genetics* / Q000378:metabolism*; D017353:Gene Deletion; D060847:Metabolic Engineering / Q000379:methods*; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D014633:Valine / Q000096:biosynthesis*
chemical_list: D000597:Amino Acids, Branched-Chain; D014633:Valine