title: Improved bioethanol production in an engineered Kluyveromyces lactis strain shifted from respiratory to fermentative metabolism by deletion of NDI1.
abstract: In this paper, we report the metabolic engineering of the respiratory yeast Kluyveromyces lactis by construction and characterization of a null mutant (Δklndi1) in the single gene encoding a mitochondrial alternative internal dehydrogenase. Isolated mitochondria of the Δklndi1 mutant show unaffected rate of oxidation of exogenous NADH, but no oxidation of matrix NADH; this confirms that KlNdi1p is the only internal NADH dehydrogenase in K. lactis mitochondria. Permeabilized cells of the Δklndi1 mutant do not show oxidation of matrix NADH, which suggests that shuttle systems to transfer the NADH from mitochondrial matrix to cytosol, for being oxidized by external dehydrogenases, are not functional. The Δklndi1 mutation decreases the chronological life span in absence of nutrients. The expression of KlNDI1 is increased by glutathione reductase depletion. The Δklndi1 mutation shifts the K. lactis metabolism from respiratory to fermentative: the Δklndi1 strain shows reduced respiration rate and increased ethanol production from glucose, while it does not grow in non-fermentable carbon sources such as lactate. The biotechnological benefit of the Δklndi1 mutant for bioethanol production from waste cheese whey lactose was proved.
authors.affiliation: Grupo de Investigación EXPRELA, Departamento de Bioloxía Celular e Molecular, Facultade de Ciencias, Universidade da Coruña, Campus de A Coruña, 15071-, A Coruña, Spain.
authors.forename: María Isabel
authors.initials: MI
authors.lastname: González-Siso
authors.forename: Alba
authors.initials: A
authors.lastname: Touriño
authors.forename: Ángel
authors.initials: Á
authors.lastname: Vizoso
authors.forename: Ángel
authors.initials: Á
authors.lastname: Pereira-Rodríguez
authors.forename: Esther
authors.initials: E
authors.lastname: Rodríguez-Belmonte
authors.forename: Manuel
authors.initials: M
authors.lastname: Becerra
authors.forename: María Esperanza
authors.initials: ME
authors.lastname: Cerdán
mesh_terms: D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D017353:Gene Deletion; D005947:Glucose / Q000378:metabolism*; D007716:Kluyveromyces / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods*; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*
chemical_list: D009243:NAD; D019344:Lactic Acid; D000431:Ethanol; D010088:Oxidoreductases; D005947:Glucose