title: Quantifying the individual effects of ethanol and temperature on the fitness advantage of Saccharomyces cerevisiae.
abstract: The presence of Saccharomyces cerevisiae in grape berries and fresh musts is usually very low. However, as fermentation progresses, the population levels of this species considerably increase. In this study, we use the concept of fitness advantage to measure how increasing ethanol concentrations (0-25%) and temperature values (4-46 °C) in wine fermentations affects competition between S. cerevisiae and several non-Saccharomyces yeasts (Hanseniaspora uvarum, Torulaspora delbrueckii, Candida zemplinina, Pichia fermentans and Kluyveromyces marxianus). We used a mathematical approach to model the hypothetical time needed for S. cerevisiae to impose itself on a mixed population of the non-Saccharomyces species described above. This approach also took into consideration the influence of environmental factors and the initial population levels of S. cerevisiae (0.1, 1.0 and 10.0%). Our results suggest that Saccharomyces niche construction via ethanol production does not provide a clear ecological advantage (at least not until the ethanol concentration exceeds 9%), whereas a temperature rise (above 15 °C) does give S. cerevisiae a considerable advantage. The initial frequency of S. cerevisiae considerably influences the time it needs to impose itself (until it reaches a final frequency of 99% in the mixed culture), the lowest time values being found at the highest initial frequency. In light of these results, the application of low temperatures in the wine industry could favor the growth and survival of non-Saccharomyces species for a longer period of time.
authors.affiliation: Departament de Bioquímica i Biotecnologia, Facultat de Enologia, Universitat Rovira i Virgili, C/Marcel·lí Domingo, s/n, 43007 Tarragona, Spain.
authors.forename: Z
authors.initials: Z
authors.lastname: Salvadó
authors.forename: F N
authors.initials: FN
authors.lastname: Arroyo-López
authors.forename: E
authors.initials: E
authors.lastname: Barrio
authors.forename: A
authors.initials: A
authors.lastname: Querol
authors.forename: J M
authors.initials: JM
authors.lastname: Guillamón
mesh_terms: D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D007218:Industrial Microbiology; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors; D014920:Wine / Q000032:analysis* / Q000382:microbiology
chemical_list: D000431:Ethanol