title: Kluyveromyces lactis and Saccharomyces cerevisiae, two potent deacidifying and volatile-sulphur-aroma-producing microorganisms of the cheese ecosystem.
abstract: Cheese flavour is the result of complex biochemical transformations attributed to bacteria and yeasts grown on the curd of smear-ripened cheeses. Volatile sulphur compounds (VSCs) are responsible for the characteristic aromatic notes of several cheeses. In the present study, we have assessed the ability of Kluyveromyces lactis, Kluyveromyces marxianus and Saccharomyces cerevisiae strains, which are frequently isolated from smear-ripened cheeses, to grow and deacidify a cheese medium and generate VSCs resulting from L-methionine degradation. The Kluyveromyces strains produced a wider variety and higher amounts of VSCs than the S. cerevisiae ones. We have shown that the pathway is likely to be proceeding differently in these two yeast genera. The VSCs are mainly generated through the degradation of 4-methylthio-oxobutyric acid in the Kluyveromyces strains, in contrast to the S. cerevisiae ones which have higher L-methionine demethiolating activity, resulting in a direct conversion of L-methionine to methanethiol. The deacidification activity which is of major importance in the early stages of cheese-ripening was also compared in S. cerevisiae and Kluyveromyces strains.
authors.affiliation: Moorepark, Teagasc Research Center, Fermoy, Ireland, UK.
authors.forename: Dafni-Maria
authors.initials: DM
authors.lastname: Kagkli
authors.forename: Roselyne
authors.initials: R
authors.lastname: Tâche
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Cogan
authors.forename: Colin
authors.initials: C
authors.lastname: Hill
authors.forename: Serge
authors.initials: S
authors.lastname: Casaregola
authors.forename: Pascal
authors.initials: P
authors.lastname: Bonnarme
mesh_terms: D002474:Cell-Free System; D002611:Cheese; D003470:Culture Media; D017753:Ecosystem; D005285:Fermentation; D005524:Food Technology / Q000379:methods; D005656:Fungal Proteins / Q000737:chemistry; D007716:Kluyveromyces / Q000378:metabolism / Q000502:physiology*; D007773:Lactates / Q000737:chemistry; D007785:Lactose / Q000737:chemistry; D008697:Methane / Q000737:chemistry; D008715:Methionine / Q000737:chemistry; D009812:Odorants; D012441:Saccharomyces cerevisiae / Q000378:metabolism / Q000502:physiology*; D013455:Sulfur / Q000737:chemistry*; D013457:Sulfur Compounds / Q000737:chemistry; D013997:Time Factors
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D007773:Lactates; D013457:Sulfur Compounds; D013455:Sulfur; D008715:Methionine; D007785:Lactose; D008697:Methane