title: A recombinant Saccharomyces cerevisiae strain overproducing mannoproteins stabilizes wine against protein haze.
abstract: Stabilization against protein haze was one of the first positive properties attributed to yeast mannoproteins in winemaking. In previous work we demonstrated that deletion of KNR4 leads to increased mannoprotein release in laboratory Saccharomyces cerevisiae strains. We have now constructed strains with KNR4 deleted in two different industrial wine yeast backgrounds. This required replacement of two and three alleles of KNR4 for the EC1118 and T73-4 backgrounds, respectively, and the use of three different selection markers for yeast genetic transformation. The actual effect of the genetic modification was dependent on both the genetic background and the culture conditions. The fermentation performance of T73-4 derivatives was clearly impaired, and these derivatives did not contribute to the protein stability of the wine, even though they showed increased mannoprotein release in vitro. In contrast, the EC1118 derivative with both alleles of KNR4 deleted released increased amounts of mannoproteins both in vitro and during wine fermentation assays, and the resulting wines were consistently less susceptible to protein haze. The fermentation performance of this strain was slightly impaired, but only with must with a very high sugar content. These results pave the way for the development of new commercial strains with the potential to improve several mannoprotein-related quality and technological parameters of wine.
authors.affiliation: Department of Microbiology, Instituto de Fermentaciones Industriales (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gonzalez-Ramos
authors.forename: Eduardo
authors.initials: E
authors.lastname: Cebollero
authors.forename: Ramon
authors.initials: R
authors.lastname: Gonzalez
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005285:Fermentation; D005516:Food Microbiology; D017353:Gene Deletion; D005800:Genes, Fungal; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D010641:Phenotype; D011134:Polysaccharides / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D014157:Transcription Factors; D014170:Transformation, Genetic; D014920:Wine / Q000382:microbiology*
chemical_list: D008562:Membrane Glycoproteins; D011134:Polysaccharides; C085451:SMI1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C025363:mannoproteins