Presently, we are aware that the bifidus bacterium genus includes 32 species. Initially they were identified by Henry Tisser, a disciple of I.I. Mechnikov, in 1899. In 1905 I.I. Mechnikov made the first attempt to use the bifidus bacteria for treatment of acute diarrhea. These days the food products containing bifidus bacteria are assigned to the functional nutrition.
B.bifidum, B.infantis, B.breve, B.longum and B.adolescentis are most important for the human gastrointestinal tract. New varieties such as B.lactis, B.inopintanum, B.denticolens, etc. have been recently discovered. Bifidus bacteria form the acetic and lactic acids but not carbon dioxide. The comfort temperature of their growth is 37-40 °C, pH = 6.5-7.0. The bifidus bacteria growth inhibited in the presence of oxygen is promoted by bicarbonates, carbohydrates and carbon dioxide. Bifidus bacteria incorporate the strictly anaerobic bacteria constituting the major part of the obligate parietal and abdominal autoflora of the large intestine of children and adults.
Being in the permanent and tight interaction with the large intestine mucosae the bifidus bacteria form an important link of the colonization resistance system of the gastrointestinal tract. The species composition of bifidus flora generally depends on the nature of diet. The expressed protective activity of bifidus bacteria results from their high adhesiveness to the large intestine mucosa. The bifidus bacterium dominance in the intestines provides the organism protection against the pathogenic microflora, which is particularly true for infants. Bifidus bacteria produce acids, lysozyme, bacteriocins, alcohol and thus prevent penetration of microbes in the upper gastrointestinal tract. Facilitating the formation of nonspecific resistance, the bifidus flora produces no noticeable antigenic action on the systemic immunity (R. Freter, 1974). It has been proved that bifidus bacterium autostrains of mother and child feature the best adhesiveness [N.A. Sinitsina (1986), M.F. Deschekina et al (1993)].