The word "bacteria" is habitual to hearing, but, as a rule, is used in negative sense. Meanwhile, these microorganisms are not only harmful, but also useful. They are called "natural hospital attendants".
1. Bacteria (from drevnegrech. - the stick) is subspecies of the microscopic organisms consisting, as a rule, of one cage. The science which is engaged in studying bacteria (bacteriology) knows about ten thousand species of bacteria today. Actually, them it is much bigger, presumably not less than one million. Other name of bacteria – microbes.
2. For the first time bacteria were seen in an optical microscope by Dutch Antoni van Levenguk in 1676, however detailed studying a bacteriological cage began only in the thirties took place centuries with the invention of an electronic microscope.
3. In bacteriology there are several branches. In medicine and veterinary science the microbiologists study pathogenic and useful bacteria, their influence on immunity level; develop and test various medicines for prevention or treatment of viral diseases of people and animals. In agriculture investigate influence of bacteria on structure and fertility of the soil. In the industrial sphere the bacteriology investigates processes of formation of alcohols, acids and so forth.
4. The world is literally populated with bacteria: they live in the soil, in water and in a human body. Any chemical process in a human body does not do without participation of these microorganisms. For example, for processing of food during chewing oral cavity bacteria, "are responsible" for digestion and processing – the bacteria which are contained in gastric juice, and making organism microflora. The immunity which is our protection against viruses and infections consists of useful bacteria.
5. Microbes "help" also in kitchen, for example, with preparation of yeast dough (yeast is lactic bacteria), kvass, curdled milk, kefir, wine (acetic bacteria), etc. However same microscopic "kids" are the reason of damage of products (emergence of a mold, decayed).