title: Production of succinic acid at low pH by a recombinant strain of the aerobic yeast Yarrowia lipolytica.
abstract: Biotechnological production of weak organic acids such as succinic acid is most economically advantageous when carried out at low pH. Among naturally occurring microorganisms, several bacterial strains are known to produce considerable amounts of succinic acid under anaerobic conditions but they are inefficient in performing the low-pH fermentation due to their physiological properties. We have proposed therefore a new strategy for construction of an aerobic eukaryotic producer on the basis of the yeast Yarrowia lipolytica with a deletion in the gene coding one of succinate dehydrogenase subunits. Firstly, an original in vitro mutagenesis-based approach was proposed to construct strains with Ts mutations in the Y. lipolytica SDH1 gene. These mutants were used to optimize the composition of the media for selection of transformants with the deletion in the Y. lipolytica SDH2 gene. Surprisingly, the defects of each succinate dehydrogenase subunit prevented the growth on glucose but the mutant strains grew on glycerol and produced succinate in the presence of the buffering agent CaCO(3). Subsequent selection of the strain with deleted SDH2 gene for increased viability allowed us to obtain a strain capable of accumulating succinate at the level of more than 45 g L(-1) in shaking flasks with buffering and more than 17 g L(-1) without buffering. The possible effect of the mutations on the utilization of different substrates and perspectives of constructing an industrial producer is discussed.
authors.affiliation: Russian State Collection of Industrial Microorganisms, State Research Institute of Genetics and Selection of Industrial Microorganisms, 1-st Dorozhny pr., 1, Moscow, Russia.
authors.forename: Tigran V
authors.initials: TV
authors.lastname: Yuzbashev
authors.forename: Evgeniya Y
authors.initials: EY
authors.lastname: Yuzbasheva
authors.forename: Tatiana I
authors.initials: TI
authors.lastname: Sobolevskaya
authors.forename: Ivan A
authors.initials: IA
authors.lastname: Laptev
authors.forename: Tatiana V
authors.initials: TV
authors.lastname: Vybornaya
authors.forename: Anna S
authors.initials: AS
authors.lastname: Larina
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Matsui
authors.forename: Keita
authors.initials: K
authors.lastname: Fukui
authors.forename: Sergey P
authors.initials: SP
authors.lastname: Sineoky
mesh_terms: D000332:Aerobiosis; D002119:Calcium Carbonate / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D050296:Microbial Viability; D016296:Mutagenesis; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D019802:Succinic Acid / Q000378:metabolism*; D025062:Yarrowia / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D019802:Succinic Acid; D013385:Succinate Dehydrogenase; D002119:Calcium Carbonate; D005947:Glucose; D005990:Glycerol