title: Increased ethanol accumulation from glucose via reduction of ATP level in a recombinant strain of Saccharomyces cerevisiae overexpressing alkaline phosphatase.
abstract: BACKGROUND
  The production of ethyl alcohol by fermentation represents the largest scale application of Saccharomyces cerevisiae in industrial biotechnology. Increased worldwide demand for fuel bioethanol is anticipated over the next decade and will exceed 200 billion liters from further expansions. Our working hypothesis was that the drop in ATP level in S. cerevisiae cells during alcoholic fermentation should lead to an increase in ethanol production (yield and productivity) with a greater amount of the utilized glucose converted to ethanol. Our approach to achieve this goal is to decrease the intracellular ATP level via increasing the unspecific alkaline phosphatase activity.
  
  
  RESULTS
  Intact and truncated versions of the S. cerevisiae PHO8 gene coding for vacuolar or cytosolic forms of alkaline phosphatase were fused with the alcohol dehydrogenase gene (ADH1) promoter. The constructed expression cassettes used for transformation vectors also contained the dominant selective marker kanMX4 and S. cerevisiae δ-sequence to facilitate multicopy integration to the genome. Laboratory and industrial ethanol producing strains BY4742 and AS400 overexpressing vacuolar form of alkaline phosphatase were characterized by a slightly lowered intracellular ATP level and biomass accumulation and by an increase in ethanol productivity (13% and 7%) when compared to the parental strains. The strains expressing truncated cytosolic form of alkaline phosphatase showed a prolonged lag-phase, reduced biomass accumulation and a strong defect in ethanol production.
  
  
  CONCLUSIONS
  Overexpression of vacuolar alkaline phosphatase leads to an increased ethanol yield in S. cerevisiae.
authors.forename: Marta V
authors.initials: MV
authors.lastname: Semkiv
authors.forename: Kostyantyn V
authors.initials: KV
authors.lastname: Dmytruk
authors.forename: Charles A
authors.initials: CA
authors.lastname: Abbas
authors.affiliation: Institute of Cell Biology, NAS of Ukraine, Drahomanov Street, 14/16, Lviv 79005, Ukraine. sibirny@cellbiol.lviv.ua.
authors.forename: Andriy A
authors.initials: AA
authors.lastname: Sibirny
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000426:Alcohol Dehydrogenase / Q000235:genetics; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism*; D018533:Biomass; D000431:Ethanol / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol; D000255:Adenosine Triphosphate; D000426:Alcohol Dehydrogenase; D000469:Alkaline Phosphatase; C510355:PHO8 protein, S cerevisiae; D005947:Glucose