Yeast

Yeasts are mushrooms and, like algae and bacteria, belong the single-celled plants making them the simplest microorganisms in the world of plants. The conversion of the sugar into alcohol is accomplished by yeasts. They multiply by separating eviscerated cells. The energy is provided by the sugar, which is dissolved in the grape must as glucose and fructose. At high temperatures, the yeasts multiply rapidly and cause a stormy fermentation.