title: Enhancement of acetoin production in Candida glabrata by in silico-aided metabolic engineering.
abstract: BACKGROUND
  Acetoin is a promising chemical compound that can potentially serve as a high value-added platform for a broad range of applications. Many industrial biotechnological processes are moving towards the use of yeast as a platform. The multi-auxotrophic yeast, Candida glabrata, can accumulate a large amount of pyruvate, but produces only trace amounts of acetoin. Here, we attempted to engineer C. glabrata to redirect the carbon flux of pyruvate to increase acetoin production.
  
  
  RESULTS
  Based on an in silico strategy, a synthetic, composite metabolic pathway involving two distinct enzymes, acetolactate synthase (ALS) and acetolactate decarboxylase (ALDC), was constructed, leading to the accumulation of acetoin in C. glabrata. Further genetic modifications were introduced to increase the carbon flux of the heterologous pathway, increasing the production of acetoin to 2.08 g/L. Additionally, nicotinic acid was employed to regulate the intracellular NADH level, and a higher production of acetoin (3.67 g/L) was obtained at the expense of 2,3-butanediol production under conditions of a lower NADH/NAD+ ratio.
  
  
  CONCLUSIONS
  With the aid of in silico metabolic engineering and cofactor engineering, C. glabrata was designed and constructed to improve acetoin production.
authors.forename: Shubo
authors.initials: S
authors.lastname: Li
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.forename: Nan
authors.initials: N
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China. mingll@jiangnan.edu.cn.
authors.forename: Liming
authors.initials: L
authors.lastname: Liu
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D000093:Acetoin / Q000378:metabolism*; D000095:Acetolactate Synthase / Q000235:genetics / Q000378:metabolism; D002072:Butylene Glycols / Q000378:metabolism; D041221:Candida glabrata / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D060847:Metabolic Engineering; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D009243:NAD / Q000378:metabolism; D009525:Niacin / Q000494:pharmacology; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic
chemical_list: D002072:Butylene Glycols; D009243:NAD; D009525:Niacin; D000431:Ethanol; C026978:2,3-butylene glycol; D002244:Carbon; D000093:Acetoin; D000095:Acetolactate Synthase; D002262:Carboxy-Lyases; C023746:acetolactate decarboxylase
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