ORIGINAL ARTICLE Correlation between cell lipid content, gene expression and fermentative behaviour of two Saccharomyces cerevisiae wine strains G. Zara 1 , L. Bardi 2 , S. Belviso 3 , G.A. Farris 1 , S. Zara 1 and M. Budroni 1 1 Dipartimento di Scienze Ambientali Agrarie e Biotecnologie Agroalimentari, Universita ` degli studi di Sassari, Sassari, Italy 2 C.R.A. Istituto Sperimentale per la Nutrizione delle Piante, SOP di Torino, Torino, Italy 3 Dipartimento di Chimica Generale ed Organica Applicata, Universita ` degli studi di Torino, Torino, Italy Introduction Stuck and slow fermentations have been recently ranked by the American Vineyard Foundation as the fourth most important enological concern to winemakers. Although mathematical models have been proposed in order to pre- dict stuck or slow fermentations, the diagnosis of the prob- lem cannot currently be carried out until the fermentation rate is seen to decrease (Bisson 1999). Several causes associ- ated with the chemical composition of must and oenologi- cal practices could be responsible for an incomplete fermentation (Bisson 1999). In particular, nitrogen and oxygen deficiencies are of major importance and have been the subject of several studies (Manginot et al. 1998; Cramer et al. 2002; Bohlscheid et al. 2007). Recently, some authors have underlined the importance of the lipid content of grape must for a correct and complete fermentation (Belviso et al. 2004; Luparia et al. 2004). Indeed, fatty acids and sterols are essential for yeast cell viability, fermentative ability and adaptation to temperature shifts and ethanol presence in the medium (Quinn et al. 1989; Vigh et al. 1998; Chi and Arneborg 1999; Aguilera et al. 2006). Lipid biosynthesis takes place in the cytoplasm, and acetyl-CoA is required (Parks 1978; Schweizer 1984). When mitochon- drial activity is absent, acetyl-CoA is produced in the cyto- plasm from acetate and CoA by Acs1p and Acs2p which Keywords fermentative behaviour, gene transcription, lipids, quantitative RT-PCR, Saccharomyces cerevisiae. Correspondence Marilena Budroni, Dipartimento di Scienze Ambientali Agrarie e Biotecnologie Agroalimentari, Universita ` degli studi di Sassari, Viale Italia, 39, 07100 Sassari, Italy. E-mail: mbudroni@uniss.it 2007 ⁄ 0353: received 6 March 2007, revised 6 September 2007 and accepted 7 September 2007 doi:10.1111/j.1365-2672.2007.03608.x Abstract Aim: To verify a possible correlation between cell lipid composition, expression of key genes in lipid metabolism and fermentative behaviour of Saccharomyces cerevisiae wine strains. Methods and Results: The fermentative abilities of two commercial wine strains of S. cerevisiae were tested under stressful conditions. Cell number, glu- cose and fructose concentrations, expression of ACS1, ACS2, ACC1, OLE1, ERG9, ERG10, ARE1 and ARE2 and lipid content were evaluated. The strain that failed to complete the fermentation had lower amounts of C16:1 and C16:0 fatty acids at the beginning of fermentation (0 h) and late logarithmic phase (72 h). While the amount of C18:1 in this strain was lower than that in the strain that completed the fermentation at 0 h, same levels were observed for both strains at 72 h. The sterol levels were generally higher in the strain that failed to complete the fermentation. Gene expression generally increased from the beginning of the fermentation to the late logarithmic phase in both strains. Conclusion: A positive correlation between good fermentative ability, elevated fatty acid content and ACC1 gene expression has been identified. Significance and Impact of the Study: The cell lipid content at the time of inoculum and expression of ACC1 gene of starter strains should be carefully considered in order to identify the possible stuck ⁄ sluggish fermentations. Journal of Applied Microbiology ISSN 1364-5072 906 Journal compilation ª 2007 The Society for Applied Microbiology, Journal of Applied Microbiology 104 (2008) 906–914 ª 2007 The Authors