Fermentation is the process of anaerobic decomposition of carbohydrates into simple connection with the release of energy that takes place with the participation of some microorganisms or a selection of these enzymes. One example of fermentation is alcohol fermentation caused by yeast and consists in decomposition of Sugars into alcohol and carbon dioxide. Also known lactic, butyric acid, acetic acid fermentation and others the Ability of microorganisms to cause fermentation with the accumulation of specific products used in industry to mass production of these substances (such as alcohol fermentation for receiving alcohol; lactic acid is in the production of yogurt and so on). On the property of some pathogens to brivati certain carbohydrates based methods of cultivation of bacterial cultures and identification of pathogens.

Fermentation is a process of decomposition of organic substances (mainly carbohydrates) under the action of enzymes produced by microorganisms. As respiration, fermentation includes redox transformations substrate associated with the release of energy. But, unlike respiration, fermentation does not produce water and carbon dioxide, and ends with the accumulation of non-completely oxidized products (alcohol, lactic acid, butyric acid and others). Under the fermentation is usually understood anaerobic process, however, this group of transformations several conditionally are also acetic acid and citrate "fermentation", although leading to the accumulation of organic acids, but committed necessarily in the presence of oxygen.
Fermentation was known in ancient times" it was used for cooking wine and vinegar. However, only in the second half of the 19th century it was determined that alcoholic fermentation linked with the livelihood of yeast (see) and is the process that provides the body with energy in the absence of oxygen. Understanding the biochemical essence of this phenomenon became possible after discharge from yeast cells fermentation systems. In 1897 Buchner (that is, Buchner) rubbed yeast with quartz sand and Tripoli and after filtration under pressure got a cell-free juice, can cause fermentation. Buchner believed that the juice contains the enzyme shimasu. Subsequently, A. N. Lebedev has proposed a new, simpler method of preparation of yeast cell-free juice. "Juice Lebedev," or "maceration juice, get dry yeast in the thermostat at the temperature of 25-30°, followed by treatment with water for 2 hours at temperature 35 degrees and filtering.
Simasa is a complex set of enzymes catalyzing the successive transformations fermentable substrate. Alcoholic fermentation is expressed total reaction equation:
It passes through a number of stages, including a mandatory part of phosphoric acid, education phosphoric esters of carbohydrates and their transformations, which is the process of oxidation, i.e., the removal of hydrogen from organic substrate. The released energy is partially disposed of in the form of rich energy ties adenosinetriphosphoric acid, which can be easily used by the cell. In this biological sense fermentation is a process that provides "life without air."
Taking into account the energy efficiency of alcoholic fermentation overall reaction equation becomes:
where ADF - by acid and ATP - adenosinetriphosphoric acid.
The difference between different types of fermentation is the substrate fermentation, and which of intermediate products is the transfer of hydrogen oxidation. If alcoholic fermentation education alcohol is the result of the transfer of hydrogen to acetaldehyde, when lactic acid fermentation recovery exposed pyruvic acid, butyric acid at fermentation due to a lack of hydrogen acceptors part of it is allocated in molecular form:
Three above-mentioned kinds of fermentation are basic. All other types are a combination of both. When acetic acid "fermentation"occurring in equation2N5OH+O2→With2N4O2+H2O, acetate, accumulated in large quantities, not an end product; the depletion of alcohol he further oxidized acetic acid bacteria to CO2 and H2o When citrate "fermentation" education of citric acid from sugar closely connected with the breathing process. Currently, it is shown that the accumulation of citric acid plesnevami mushrooms is only one link in the complex chain of oxidative transformations of di - and tricarboxylic acids, called citrate cycle (see biological Oxidation).
Education citric acid occurs only as long, while the supply of substrate is not exhausted. With full use of sugar accumulated citric acid undergoes a deeper oxidation. Significant accumulation of citric acid in the cultures of fungi enables to use them in the technique for obtaining of citric acid from sugar. Practical application is found with other types of fermentation.
Alcoholic fermentation is used for industrial production of alcohol. As raw material use products containing starch, potato, maize, cereals, and also a waste of sugar production and wood industry. For starch saccharification pretreated amylase malt. Fermentation lead on clean yeast cultures characterized by stability to high levels of alcohol. Different yeast races are used for the production of beer b grape wine. In baking use compressed yeast is a mixture of several races of yeast. Formed during fermentation alcohol and CO2 loosen the dough and cause it to rise, and by-products B. give the bread a peculiar taste and aroma. Important technical importance obtaining glycerin modified by alcohol B. Alcoholic fermentation can also be used in clinical tests. In the study of biological liquids on the content of sugar (glucose and fructose) use the so-called fermentation test, namely, that at addition of yeast, sugar is subjected to fermentation emitting CO2 (detected by the absorption of alkali) and ethyl alcohol, the existence of which is recognized by the formation of iodoform in reaction with iodine in an alkaline environment.
Lactic b is caused by microorganisms, widespread in nature. They are contained in many fruits and vegetables, rye flour, malt, silage, etc. But the primary environment for their development is milk, where under the influence they formed lactic acid comes the collapse of casein. For protection from souring milk is subjected to pasteurization, which causative agents of lactic fermentation die. The most widely lactic acid B. used in the manufacture of yogurt, yogurt, acidophilus etc. of acido-Lactic bacteria that can live in the intestines, suppress it putrefactive microflora.
Butyric acid B. excited by a group of anaerobic bacteria found in soil, air, polluted water, clusters decomposing plant residues. Butyric acid bacteria form resistant spores that can withstand boiling for several minutes. They are sensitive to acid and therefore their activity is manifested where lactic fermentation excluded (pasteurized milk) or strongly suppressed (raw milk during prolonged storage at cold). Characteristic features of butyric acid b - emission gas, sharp smell of butyric acid, purchase a product unpleasant taste. In canned canned products and cheeses you experience swelling. This b may develop in crude flour, giving it a bitter taste.