Activation of Two Different Resistance Mechanisms in Saccharomyces cerevisiae upon Exposure to Octanoic and Decanoic Acids

• Published in: Applied and Environmental Microbiology 2010-11, Vol.76 (22), p.7526-7535
• Main Authors: Legras, J.L, Erny, C, Le Jeune, C, Lollier, M, Adolphe, Y, Demuyter, C, Delobel, P, Blondin, B, Karst, F
• Format: Article
• Language: English
• Subjects: Acidity; Antifungal Agents - toxicity; Biological and medical sciences; Caprylates - toxicity; decanoic acid; Decanoic Acids - toxicity; Drug Resistance, Fungal; esters; ethanol; Fatty acids; Fermentation; Fundamental and applied biological sciences. Psychology; gene activation; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Fungal - drug effects; genes; Genetics and Molecular Biology; Genotype & phenotype; grape must; Life Sciences; Microbiology; octanoic acid; Oxidation; Oxidative stress; resistance mechanisms; Saccharomyces cerevisiae; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae Proteins - metabolism; stress response; Stress, Physiological; toxicity; transcription factors; transcriptome; transporters; Vegetal Biology; Yeast
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.01280-10

Medium-chain fatty acids (octanoic and decanoic acids) are well known as fermentation inhibitors. During must fermentation, the toxicity of these fatty acids is enhanced by ethanol and low pH, which favors their entrance in the cell, resulting in a decrease of internal pH. We present here the characterization of the mechanisms involved in the establishment of the resistance to these fatty acids. The analysis of the transcriptome response to the exposure to octanoic and decanoic acids revealed that two partially overlapping mechanisms are activated; both responses share many genes with an oxidative stress response, but some key genes were activated differentially. The transcriptome response to octanoic acid stress can be described mainly as a weak acid response, and it involves Pdr12p as the main transporter. The phenotypic analysis of knocked-out strains confirmed the role of the Pdr12p transporter under the control of WAR1 but also revealed the involvement of the Tpo1p major facilitator superfamily proteins (MFS) transporter in octanoic acid expulsion. In contrast, the resistance to decanoic acid is composite. It also involves the transporter Tpo1p and includes the activation of several genes of the beta-oxidation pathway and ethyl ester synthesis. Indeed, the induction of FAA1 and EEB1, coding for a long-chain fatty acyl coenzyme A synthetase and an alcohol acyltransferase, respectively, suggests a detoxification pathway through the production of decanoate ethyl ester. These results are confirmed by the sensitivity of strains bearing deletions for the transcription factors encoded by PDR1, STB5, OAF1, and PIP2 genes.