Life and Earth Sciences | Madrid, May 10-11, 2011
INTRODUCTIONYeasts are the microorganisms for which the most ancient written record exists. Evidence of processes in which yeasts participate appears also in archaeological findings pertaining for old civilizations. These testimonies demonstrate the long companionship between yeasts and humans. The population concentration in cities brought about by the industrial revolution in the XIX century forced a change in the ways of production of many commodities so that some processes carried out by yeasts and done previously in artisanal ways needed to be adapted to mass production. For example, the amount of yeast for bread production could no longer be satisfied by the breweries supply and this led to development of processes devoted to produce yeast as such. Simultaneously, spoilage problems in fermentations that had only been nuisances in small household activities became financially important in factories and a matter of concern for industrialists some of which had the vision to interest scientists in these problems. In this way yeasts, mainly Saccharomyces cerevisiae, became respected microorganisms. Let us not forget the contributions of those pioneers who, sometimes suffering vicious attacks by established scientists, paved the roads that have led to the current situation. A situation that allows us to examine the advances reached and the perspectives opened by the use of yeasts as models and tools. Models and tools are different concepts; as defined by the Oxford English Dictionary a Model is: "A simplified or idealized description or construction of a particular system, situation or process that is put forward as a basis for calculations, predictions or further investigation" and a Tool is defined as: "A thing with which some operation is performed; a mean of effecting something". In the use of yeasts for purposes different from their natural activities both concepts merge in a rational operational unit; the utilization of yeasts to simulate a situation found in other organisms is a use of them as model, this is often followed by their use to perform some operation with them, a use as a tool.