title: NAD-independent L-lactate dehydrogenase is required for L-lactate utilization in Pseudomonas stutzeri SDM.
abstract: BACKGROUND
  Various Pseudomonas strains can use L-lactate as their sole carbon source for growth. However, the L-lactate-utilizing enzymes in Pseudomonas have never been identified and further studied.
  
  
  RESULTS
  An NAD-independent L-lactate dehydrogenase (L-iLDH) was purified from the membrane fraction of Pseudomonas stutzeri SDM. The enzyme catalyzes the oxidation of L-lactate to pyruvate by using FMN as cofactor. After cloning its encoding gene (lldD), L-iLDH was successfully expressed, purified from a recombinant Escherichia coli strain, and characterized. An lldD mutant of P. stutzeri SDM was constructed by gene knockout technology. This mutant was unable to grow on L-lactate, but retained the ability to grow on pyruvate.
  
  
  CONCLUSIONS
  It is proposed that L-iLDH plays an indispensable function in Pseudomonas L-lactate utilization by catalyzing the conversion of L-lactate into pyruvate.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Gao
authors.forename: Tianyi
authors.initials: T
authors.lastname: Jiang
authors.forename: Peipei
authors.initials: P
authors.lastname: Dou
authors.forename: Cuiqing
authors.initials: C
authors.lastname: Ma
authors.forename: Lixiang
authors.initials: L
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Kong
authors.forename: Ping
authors.initials: P
authors.lastname: Xu
mesh_terms: D000595:Amino Acid Sequence; D003067:Coenzymes / Q000378:metabolism; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009243:NAD / Q000378:metabolism; D044223:Pseudomonas stutzeri / Q000201:enzymology* / Q000378:metabolism; D017421:Sequence Analysis
chemical_list: D003067:Coenzymes; D009243:NAD; D019344:Lactic Acid; D007770:L-Lactate Dehydrogenase