A systems biology perspective of wine fermentations

Abstract

The yeast Saccharomyces cerevisiae is an important industrial microorganism. Nowadays, it is being used as a cell factory for the production of pharmaceuticals such as insulin, although this yeast has long been utilized in the bakery to raise dough, and in the production of alcoholic beverages, fermenting the sugars derived from rice, wheat, barley, corn and grape juice. S. cerevisiae has also been extensively used as a model eukaryotic system. In the last decade, genomic techniques have revealed important features of its molecular biology. For example, DNA array technologies are routinely used for determining gene expression levels in cells under different physiological conditions or environmental stimuli. Laboratory strains of S. cerevisiae are different from wine strains. For instance, laboratory yeasts are unable to completely transform all the sugar in the grape must into ethanol under winemaking conditions. In fact, standard culture conditions are usually very different from winemaking conditions, where multiple stresses occur simultaneously and sequentially throughout the fermentation. The response of wine yeasts to these stimuli differs in some aspects from laboratory strains, as suggested by the increasing number of studies in functional genomics being conducted on wine strains. In this paper we review the most recent applications of post-genomic techniques to understand yeast physiology in the wine industry. We also report recent advances in wine yeast strain improvement and propose a reference framework for integration of genomic information, bioinformatic tools and molecular biology techniques for cellular and metabolic engineering. Finally, we discuss the current state and future perspectives for using 'modern' biotechnology in the wine industry.

Peculiar H + Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation

“…Numerous genes have been reported to be up-or downregulated, revealing the possible implication of several pathways, such as the regulatory HOG and TOR pathways (8,31), transcription machinery and RNA processing (28), protein trafficking and vacuolar function and transport (5,37), peroxisome import protein machinery (34), and lipid membrane and wall biosynthesis (15). However, most of these studies were centered on active growing cells, with less attention being paid to late stages of fermentation.…”

Biological Demalication and Deacetification of Musts and Wines: Can Wine Yeasts Make the Wine Taste Better?

“…In fermentation or refermentation, multiple stress conditions are imposed on the yeast cell such as high osmolarity; low pH; sulfur dioxide (SO 2 ); ethanol toxicity; temperature variations; increasing nitrogen limitation; and elevated acetic acid concentrations. All of these stress conditions may lead to reduced cellular growth, cellular death and, consequently, stuck fermentations [14,[66][67][68].…”

DNA Arrays

“…Whole-genome expression profiling can measure the transcriptional gene response to conditions or treatments of interest in a single assay, such as chemical or environmental agents (Jelinsky and Samson 1999;Jelinsky et al 2000;Gasch et al 2000;Hughes et al 2000a;Pizarro et al 2007). In an experiment that studied varied environmental conditions, the authors actually found that while a large set of genes showed similar response to almost all conditions studied, others were specialized for specific responses (Gasch et al 2000).…”

“…Given the utility of DNA arrays in investigating how interesting genes change their expression throughout a biological process, several attempts were carried out in wine yeasts at the beginning of the twenty-first century (reviewed in Pérez-Ortín et al 2002b;Pizarro et al 2007). Once more, the yeast S. cerevisiae was the first microorganism in which wild living strains (different from the model strain used for the array probes design) of industrial interest were studied using this powerful technique.…”

“…), low nitrogen content and presence of inhibitors such as sulphite and, later, nitrogen and carbon sources starvation and high ethanol concentration (up to 15% v/v) (reviewed in Attfield 1997 andPizarro et al 2007). It is worth mentioning that during the whole wine production process, from the preparation of active dry yeast to biological ageing (if required), the plethora of stress situations to which cells are subjected is even wider.…”