title: Relationship between ethanol and oxidative stress in laboratory and brewing yeast strains.
abstract: Ethanol is a chemical stress factor that inhibits cellular growth and determines metabolic changes leading to reduction of cell viability during fermentation and yeast storage. To determine the effect of time, temperature and ethanol during storage of brewing yeasts we have monitored viability of cells stored for 72 h, at 6 °C or 12 °C, in the presence of various ethanol concentrations. Under the conditions tested, 6 °C is the most favourable temperature to store brewing yeast creams emphasizing the importance of a tight temperature control in the storage vessels. Because W210 is less resistant to storage in the presence of ethanol than W34/70, the optimal storage parameters obtained under our laboratory conditions vary significantly. The ale strain is sensitive to storage under ethanol concentrations higher than 5% (v/v) for more than 48 h at 6 °C whereas at the same temperature the lager strain tolerates ethanol up to 7.5% (v/v) for 72 h. Also, the viability assays indicate that the antioxidant protein Yap1 is an important factor to storage resistance of BY4741 laboratory strain. To investigate the molecular mechanisms underlying tolerance of brewing yeast strains to ethanol, we have performed phenotypic analysis, localization studies and have monitored the activation of antioxidant and protection genes as well as the intracellular contents of glycogen and trehalose. Overall, our data suggest that the ale strain W210 has a defective antioxidant defence system and that ethanol may induce the antioxidant defences as well as glycogen and trehalose protection mechanisms in laboratory and brewing yeast strains.
authors.affiliation: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República - Estação Agronómica Nacional, 2780-157 Oeiras, Portugal; "Dunarea de Jos" University of Galati, Food Science and Engineering Faculty, Domneasca Street, No. 111, 800201 Galati, Romania.
authors.forename: Iulia
authors.initials: I
authors.lastname: Bleoanca
authors.forename: Ana Rita Courelas
authors.initials: AR
authors.lastname: Silva
authors.forename: Catarina
authors.initials: C
authors.lastname: Pimentel
authors.forename: Claudina
authors.initials: C
authors.lastname: Rodrigues-Pousada
authors.forename: Regina de Andrade
authors.initials: Rde A
authors.lastname: Menezes
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001515:Beer / Q000382:microbiology*; D000431:Ethanol / Q000494:pharmacology*; D005285:Fermentation; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014199:Trehalose / Q000378:metabolism
chemical_list: D000975:Antioxidants; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C086677:YAP1 protein, S cerevisiae; D000431:Ethanol; D006003:Glycogen; D014199:Trehalose; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase
keywords: Antioxidant responses; GPH1; Glycogen; SOD1; TPS1; Trehalose; W210; W34/70; Yap1; Yeast storage