Dynamics of the Saccharomyces cerevisiae Transcriptome during Bread Dough Fermentation

Abstract

The behavior of yeast cells during industrial processes such as the production of beer, wine, and bioethanol has been extensively studied. In contrast, our knowledge about yeast physiology during solid-state processes, such as bread dough, cheese, or cocoa fermentation, remains limited. We investigated changes in the transcriptomes of three genetically distinct Saccharomyces cerevisiae strains during bread dough fermentation. Our results show that regardless of the genetic background, all three strains exhibit similar changes in expression patterns. At the onset of fermentation, expression of glucose-regulated genes changes dramatically, and the osmotic stress response is activated. The middle fermentation phase is characterized by the induction of genes involved in amino acid metabolism. Finally, at the latest time point, cells suffer from nutrient depletion and activate pathways associated with starvation and stress responses. Further analysis shows that genes regulated by the high-osmolarity glycerol (HOG) pathway, the major pathway involved in the response to osmotic stress and glycerol homeostasis, are among the most differentially expressed genes at the onset of fermentation. More importantly, deletion of HOG1 and other genes of this pathway significantly reduces the fermentation capacity. Together, our results demonstrate that cells embedded in a solid matrix such as bread dough suffer severe osmotic stress and that a proper induction of the HOG pathway is critical for optimal fermentation.

Transcriptional response of Saccharomyces cerevisiae to low temperature during wine fermentation

“…Therefore, it is likely that these functional categories as a whole are important for cold adaptation and follow a more general stress response that is conserved from strain to strain. Similar results were obtained in a transcriptomic study of three genetically diverse S. cerevisiae strains during bread dough fermentation (Aslankoohi et al 2013). Despite differences in genetic background, strains fermented in bread dough induced pathways related to nutrient deprivation, namely carbon and nitrogen, as well as stress-related genes.…”

Evolution of moonlighting proteins: insight from yeasts

“…In the case of Hxk2 from S. cerevisiae, it will be necessary to delineate its structural requirements to interact with Mig1 and perhaps with other proteins that participate in catabolite repression. In baker's yeast strains, too, quantitative differences between the transcriptomes of industrial strains and those of other strains during dough fermentation have been described [48]. Another question to answer is whether the continued use of S. cerevisiae by humans might have influenced the moonlighting properties of Hxk2.…”

Artisanal cachaça and brewer's spent grain as sources of yeasts with promising biotechnological properties

“…The deletion of the HOG gene is an example of possible gene alteration, resulting in the reduction in fermentative capacity (Aslankoohi et al . ).…”

“…The massive cell production can represent an unnecessary energy loss, once there is a consistent cell production under normal fermentation conditions with cell recycling, reaching between 50 and 80 kg yeast for each m 3 of ethanol produced industrially (Aslankoohi et al . ; Lopes et al . ).…”