Transcriptional response of Saccharomyces cerevisiae to low temperature during wine fermentation

Abstract

Although the yeast response to low temperature has industrial significance for baking, lager brewing and white wine fermentation, the molecular response of yeast cells to low temperature remains poorly characterised. Transcriptional changes were quantified in a commercial wine yeast, Enoferm M2, fermented at optimal (25 °C) and low temperature (12.5 °C), at two time points during fermentation of Sauvignon blanc grape juice. The transition from early to mid-late fermentation was notably less severe in the cold than at 25 °C, and the Rim15p-Gis1p pathway was involved in effecting this transition. Genes for three key nutrients were strongly influenced by low temperature fermentation: nitrogen, sulfur and iron/copper, along with changes in the cell wall and stress response. Transcriptional analyses during wine fermentation at 12.5 °C in four F1 hybrids of M2 also highlighted the importance of genes involved in nutrient utilisation and the stress response. We identified transcription factors that may be important for these differences between genetic backgrounds. Since low fermentation temperatures cause fundamental changes in membrane kinetics and cellular metabolism, an understanding of the physiological and genetic limitations on cellular performance will assist breeding of improved industrial strains.

Saccharomyces cerevisiae FLO1Gene Demonstrates Genetic Linkage to Increased Fermentation Rate at Low Temperatures

“…In contrast to SWH1 , FLO1 has a very repetitive gene structure and the allele from RM11-1a has multiple large deletions compared to S288C (see File S2). Additionally, FLO1 is very highly expressed during fermentation at 12.5° in an F 1 hybrid constructed by crossing another wine strain, Enoferm M2, with S288C (Deed et al 2015). According to standard understanding, FLO1 is not expressed in S288C because FLO8 , encoding its transcriptional regulator, has a nonsense mutation and is nonfunctional; however, there are reports of FLO1 being activated in a Flo8p-independent manner (Bester et al 2006; Shen et al 2006; Fichtner et al 2007).…”

“…Smukalla et al (2008) have shown that S288C cells engineered to express a Flo1+ flocculation phenotype also upregulate genes involved in cell wall, lipid, and sterol metabolism, which are also induced during the stress response to low temperatures (Beney et al 2001; Gasch and Werner-Washburne 2002; Beltran et al 2008; Redón et al 2011; Deed et al 2015). Additionally, genes within the DAN/TIR and PAU gene families, which have long been associated with the transcriptional response of S. cerevisiae to low temperature (Kondo and Inouye 1991; Abramova et al 2001; Homma et al 2003; Schade et al 2004), including during fermentation at low temperatures (Beltran et al 2006; Deed et al 2015), are also induced in flocculating cells (Smukalla et al 2008). Low fermentation temperatures may also favor flocculation due to reduced turbulence from the lower metabolic rate and slower CO 2 formation (Soares 2011).…”

“…In RM11-1a, the FLO8 gene is functional and Brem et al (2002) found that one-quarter of the F 1 progeny from the BY4716 × RM11-1a cross showed a flocculation phenotype (Flo1+ and Flo8+). Gene expression microarray data from Deed et al (2015) show that FLO1 transcripts in a M2 × S288C F 1 hybrid are dramatically upregulated during low temperature fermentation compared to the M2 parental reference. FLO1 was upregulated 73-fold at early fermentation (2% weight loss) and 182-fold at midlate fermentation (70% weight loss).…”

“…, high sugar, ethanol and toxic fatty acid concentrations, low pH, reduced concentrations of oxygen, and limited nitrogen. Therefore, the added stress of low fermentation temperatures requires an even greater response by S. cerevisiae , corresponding to altered transcription of ∼500–1000 genes depending on the strain and conditions used (Beltran et al 2006; Deed et al 2015). The transcriptional response to low temperature fermentation is initiated in two steps, first via the induction of cold-specific stress genes, followed by the more generalized environmental stress response and fermentation stress response (Gasch and Werner-Washburne 2002; Beltran et al 2006; Marks et al 2008; Deed et al 2015).…”

“…Therefore, the added stress of low fermentation temperatures requires an even greater response by S. cerevisiae , corresponding to altered transcription of ∼500–1000 genes depending on the strain and conditions used (Beltran et al 2006; Deed et al 2015). The transcriptional response to low temperature fermentation is initiated in two steps, first via the induction of cold-specific stress genes, followed by the more generalized environmental stress response and fermentation stress response (Gasch and Werner-Washburne 2002; Beltran et al 2006; Marks et al 2008; Deed et al 2015). It has been well documented that different S. cerevisiae strains vary greatly in their ability to grow and ferment at lower temperatures (Charoenchai et al 1998; Torija et al 2003), and it has been suggested that these phenotypic differences are due to strain differences in gene expression, particularly via variation in gene promoter regions and the expression of transcription factors (Beltran et al 2006; Chiva et al 2012; Treu et al 2014; Deed et al 2015).…”