Poster Presentation 2-19

A Genomic Analysis of the Dynamic Adaptation of the Yeast Saccharomyces cerevisiae to High Concentration of Produced Ethanol

Marlène Cot,³ Sandrine Alfenore,³ Cameleyre Xavier,³ Véronique le Berre,^1,2 Serguei Sokol,² Sylvain Jasson,⁴ Jean-Louis Uribelarrea,¹ Carole Molina-Jouve,¹ Gérard Goma,¹

Jean François,^1,2 Stéphane Guillouet¹ and Laurent Benbadis^1*

¹Centre de Bioingenierie Gilbert Durand

UMR CNRS5504, UR INRA 792

Département de Génie Biochimique et Alimentaire

INSA – 135 av de Rangueil

31077 TOULOUSE Cedex – France

Phone: +33 (0) 561559420

Fax: +33 (0) 561559400

E-mail: laurent.benbadis@insa-tlse.fr

²Transcriptome - Biopchips plateform of Genopole Toulouse

³CRITT Bio-Industrie, 135 Avenue de Rangueil, F-31077 Toulouse, France

⁴INRA, Chemin Borde Rouge, F-31326, Castanet-Tolosan

The aim of this project is to identify genes involved in ethanol adaptation mechanisms discovered during ethanol fermentation to define relevant genetic targets for metabolically engineering yeast to improve its performance. The expression changes that occurred during an original fermentation process (that allows the yeast S. cerevisiae to produce in less than 45 h more than 150 g/l ethanol (i.e. 18.9°GL), was quantified using DNA chip technology at six different time-points during fed-batch fermentation.

A global functional analysis of the expression changes revealed 300 genes during the growth phase and 600 genes during the uncoupling phase. A clustering analysis was applied and allowed identification of the expression changes of two major groups of genes. One characterized the declining growth phase and concerned down-regulated genes involved in protein synthesis, transcription and transduction. The second group characterized the uncoupling phase after the growth arrest and gathered up-regulated genes involved in central metabolism, redox balance and phospholipid, fatty acid and sterol metabolism. Further studies are focusing on lipid composition of the cells to reveal changes in lipid content that might correlate to the observed expression changes of genes.