title: Evolution-based strategy to generate non-genetically modified organisms Saccharomyces cerevisiae strains impaired in sulfate assimilation pathway.
abstract: OBJECTIVE
  An evolution-based strategy was designed to screen novel yeast strains impaired in sulfate assimilation. Specifically, molybdate and chromate resistance was used as selectable phenotype to select sulfate permease-deficient variants that unable to produce sulfites and hydrogen sulfide (H(2) S).
  
  
  RESULTS
  Four Saccharomyces cerevisiae parent strains were induced to sporulate. After tetrad digestion, spore suspensions were observed under the microscope to monitor the conjugation of gametes. Then, the cell suspension was inoculated in tubes containing YPD medium supplemented with ammonium molybdate or potassium chromate. Forty-four resistant strains were obtained and then tested in microvinifications. Three strains with a low sulfite production (SO2 < 10 mg l(-1)) and with an impaired H2S production in grape must without added sulfites were selected.
  
  
  CONCLUSIONS
  Our strategy enabled the selection of improved yeasts with desired oenological characteristics. Particularly, resistance to toxic analogues of sulfate allowed us to detect strains that unable to assimilate sulfates.
  
  
  CONCLUSIONS
  This strategy that combines the sexual recombination of spores and application of a specific selective pressure provides a rapid screening method to generate genetic variants and select improved wine yeast strains with an impaired metabolism regarding the production of sulfites and H2S.
authors: Department of Agricultural and Food Sciences (DipSAA), University of Modena and Reggio Emilia, Reggio Emilia, Italy. luciana.devero@unimore.it
authors: L
authors: L
authors: De Vero
authors: L
authors: L
authors: Solieri
authors: P
authors: P
authors: Giudici
mesh_terms: D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism; D005075:Biological Evolution; D006862:Hydrogen Sulfide / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*; D013447:Sulfites / Q000378:metabolism; D013458:Sulfur Dioxide / Q000378:metabolism; D013461:Sulfur Oxides / Q000378:metabolism; D027843:Vitis / Q000378:metabolism; D014920:Wine / Q000382:microbiology; D015003:Yeasts / Q000378:metabolism
chemical_list: D027321:Anion Transport Proteins; D013431:Sulfates; D013447:Sulfites; D013461:Sulfur Oxides; D013458:Sulfur Dioxide; C022702:sulfate permease; D006862:Hydrogen Sulfide