title: [Modification of carbon flux in Sacchromyces cerevisiae to improve L-lactic acid production].
abstract: OBJECTIVE
  We developed an engineered Sacchromyces cerevisiae strain to produce L-lactic acid efficiently by using glucose as carbon source.
  
  
  METHODS
  For construction of the strain CEN. PK2-1C [LDH], we integrated an LDH gene coding L-lactic acid dehydrogenase from bovine into the genome of S. cerevisiae via homologous recombination and meanwhile knocked out a PDC1 gene coding pyruvate decarboxylase. The carbon fluxes were led into L-Lactic acid. We analyzed the Km value of these key enzymes to NADH and over-expressed an NADH oxidase (nox) from Streptococcus pneumoniae into the cytoplasm for the construction of S. cerevisiae CEN. PK2-1C [LDH] -nox.
  
  
  RESULTS
  Compared to the initial strain, the yield of L-lactic acid in CEN. PK2-1C [LDH] fermentation broth increased from 0 g/L to 15 g/L and the concentration of ethanol decreased from 27.3 g/L to 16.2 g/L. Compared to CEN. PK2-1C [LDH], the yield of L-lactic acid in CEN. PK2-1C [LDH] -nox fermentation broth increased from 15 g/L to 20 g/L and the concentration of ethanol decreased from 16.2 g/L to 8.2 g/L.
  
  
  CONCLUSIONS
  The carbon metabolic flux was redistributed to efficient accumulation of L-lactic acid through two-sided control that heterologous expression of the gene LDH and decreasing the ratio of NADH/NAD+.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China. liangzhao1@hotmail.com
authors.forename: Liangliang
authors.initials: L
authors.lastname: Zhao
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Jingwen
authors.initials: J
authors.lastname: Zhou
authors.forename: Liming
authors.initials: L
authors.lastname: Liu
authors.forename: Guocheng
authors.initials: G
authors.lastname: Du
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D000818:Animals; D002244:Carbon / Q000378:metabolism*; D002417:Cattle; D005285:Fermentation; D005818:Genetic Engineering; D007770:L-Lactate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D019344:Lactic Acid / Q000096:biosynthesis*; D011767:Pyruvate Decarboxylase / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D019344:Lactic Acid; D002244:Carbon; D007770:L-Lactate Dehydrogenase; D011767:Pyruvate Decarboxylase