Yeast is the key component in the creation ethanol, an environmentally friendly fuel produced through the use of fermentation . This is the process of growing certain yeasts in order to produce various chemical compounds, like ethanol. Bacteria are members of a large group of microorganisms with a very simple cell structure. Some bacteria manufacture their own food, others live in association with other organisms and some live on organic matter. One of the most important uses of bacteria is as tools to study inheritance and expression of genetic trails.
Bacteria are everywhere.
Researchers have even discovered bacteria in solid rock many kilometres below the earth's surface, in hot springs and in salty water. These bacteria survive even though there is very little organic material available to them. Viruses are extremely tiny organisms which contain genetic information, but which cannot reproduce on their own. To reproduce, they must invade the cells of another organism and use the cells' reproductive machinery. Viruses are parasites of animals, plants and some bacteria-they must use the cells of these other organisms in order to live.