Transcriptome analysis of the thermotolerant yeast Kluyveromyces marxianus CCT 7735 under ethanol stress
The thermotolerant yeast Kluyveromyces marxianus displays a potential to be used for ethanol production from both whey and lignocellulosic biomass at elevated temperatures, which is highly alluring to reduce the cost of the bioprocess. Nevertheless, contrary to Saccharomyces cerevisiae, K. marxianus cannot tolerate high ethanol concentrations. We report the transcriptional profile alterations in K. marxianus under ethanol stress in order to gain insights about mechanisms involved with ethanol response. Time-dependent changes have been characterized under the exposure of 6% ethanol and compared with the unstressed cells prior to the ethanol addition. Our results reveal that the metabolic flow through the central metabolic pathways is impaired under the applied ethanol stress. Consistent with these results, we also observe that genes involved with ribosome biogenesis are downregulated and gene-encoding heat shock proteins are upregulated. Remarkably, the expression of some gene-encoding enzymes related to unsaturated fatty acid and ergosterol biosynthesis decreases upon ethanol exposure, and free fatty acid and ergosterol measurements demonstrate that their content in K. marxianus does not change under this stress. These results are in contrast to the increase previously reported with S. cerevisiae subjected to ethanol stress and suggest that the restructuration of K. marxianus membrane composition differs in the two yeasts which gives important clues to understand the low ethanol tolerance of K. marxianus compared to S. cerevisiae.
KeywordsKluyveromyces marxianus Transcriptome Ethanol stress Membrane
This study was supported by the Brazilian Agencies CNPq (National Science and Technology Development Council), CAPES (Coordination for the Improvement of Higher Education Personnel), and FAPEMIG (Foundation for Research Support of the State of Minas Gerais). The work carried out at Universidade da Coruña was cofunded from Xunta de Galicia (Consolidación D.O.G. 10-10-2012. Contract no. 2012/118 and D.O.G 12-20-2016 Contract no ED431C-2016-012) cofinanced by FEDER. The work performed at University of Tartu was funded by European Research Council (project SynBioTEC) and Estonian Research Council (grant PUT1488). The authors thank the Center for Analysis of Biomolecules of Universidade Federal de Viçosa for the equipment and software used in this study.
RHSD, MLM, and NMV executed the bench procedures. PJL, PMPV, and JCV performed the bioinformatics procedures. JCV, PJL, and WBDS analyzed the data. MIGS and MEC supervised the work at the Spanish laboratory and contributed to data interpretation. JCV, MCTA, PJL, and WBDS wrote the manuscript. WBDS designed and supervised the overall of research project. All authors have read and approved the final version of the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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