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Basic physiological functions of the intestinal bacterial flora

 
, medical expert
Last reviewed: 11.04.2020
 
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According to the theory of balanced nutrition, the colonization of the bacterial flora of the digestive tract of higher organisms is an undesirable and to some extent harmful side effect. However, the bacterial flora of the gastrointestinal tract is not only not harmful, but necessary for the normal development of the physiological functions of the macroorganism, and its phylogenetic and ontogenetic development is closely related to the biocenosis of microorganisms.

The microflora of the digestive apparatus also affects its functional characteristics. In particular, bacterial enterotoxins significantly affect intestinal permeability. In most cases, the enzymatic activity of the small intestine in non-microbial organisms is higher than in conventional organisms. Nevertheless, there are reports that the level of disaccharidase activity of the small intestine of non-microbial and common rats is the same. The information about pancreatic enzymes is also contradictory. According to one data, their activity in non-microbial animals is higher than in ordinary animals, according to others - it is the same. Finally, it should be noted that dysbacteriosis leads to a decrease in the enzymatic activity of the small intestine and, accordingly, to violations of the membrane digestion.

Intestinal microflora determines the attitude towards the immune defense of the body. Two mechanisms of local immunity are being discussed. The first is to inhibit the adhesion of bacteria to the intestinal mucus mediated by local antibodies, including IgA. The second mechanism is to control the number of a certain bacterial population located on the surface of the intestinal mucosa, due to the presence of antibacterial antibodies in this area. Compared to conventional animals, non-microbial organisms contain only 10% of cells producing IgA, which participates in local immunity. It was demonstrated that the content of total protein, alpha, beta and gamma globulins in blood plasma in non-microbial animals is lower than in normal animals. In the absence of an ordinary microflora with normal phagocytosis in micro-macrophages, the hydrolysis of antigens slows them down.

It should, however, be borne in mind that anaerobic fermentation also produces (more often as individual products) formic, succinic and lactic acids and some hydrogen. The determination of hydrogen is widely used to diagnose diseases of the small and especially large intestine.

Thus, the bacterial flora of the gastrointestinal tract is a kind of trophic homeostat, or trophostat, which ensures the destruction of excess food components and the formation of missing foods. In addition, some products of its vital activity participate in the regulation of a number of macroorganism functions. Therefore, maintenance of normal bacterial flora in the body becomes one of the most important tasks of optimizing nutrition and vital activity of higher organisms, including humans.

The bacterial population of the intestinal mucosa significantly differs from the cavitary in terms of both composition and biochemical characteristics. In our laboratory in 1975 it was shown that among the bacterial population of the small intestine mucosa there are almost no hemolyzing forms that are widely represented in the cavity population. Already at that time we suggested that the mucosal population is autochthonous and largely determines the composition of the cavity population. At the same time, it was found that with a change in diet and diseases, there are more severe violations of the mucosal population, rather than cavitary.

The idea of II. Mechnikov on the expediency of suppressing the intestinal bacterial flora must now be subjected to a fundamental revision. Indeed, as already noted, the comparison of conventional and non-microbial organisms allowed us to conclude that the latter in the metabolic, immunological and even neurological respect are defective and sharply differ from the usual ones.

As already noted, the symbiosis of micro- and macroorganisms is probably an ancient evolutionary acquisition and is already observed at the level of primitive multicellular organisms. In any case, during the evolution of most multicellular organisms a symbiosis with bacteria of certain types arose.

In fact, bacterial flora is a necessary attribute of the existence of complex organisms. The latter, according to modern ideas, should be viewed as a single system of a higher hierarchical level than a single individual. In this case, the macroorganism in relation to microorganisms fulfills the function of the dominant and regulator of the whole system as a whole. Between it and symbionts there is an exchange of metabolites, which contain nutrients, various inorganic components, stimulants, inhibitors, hormones and other physiologically active compounds. Suppression of bacterial flora of the intestine often leads to a shift in the metabolic balance of the body.

Thus, at present it becomes clear that in the metabolic sense the organism is a superorganismic system consisting of a dominant multicellular organism and a specific bacterial polyculture, and sometimes Protozoa.

Endoecosystems have the capacity for self-regulation and are sufficiently stable. At the same time, they have some critical limits of sustainability, behind which their irreparable violation occurs. Normal endoecology can be disturbed by specific and nonspecific effects, which leads to a dramatic change in the flow of bacterial metabolites. Violation of the composition of the bacterial population of the intestine was found, in particular, with a change in the composition of the diet, with diseases of the gastrointestinal tract, under the influence of various extreme factors (for example, under stress, including emotional, under special conditions, etc.). Dysbacteriosis occurs for various reasons, in particular due to the use of antibiotics.

Thus, various variants and links of those trophic chains, which we traditionally refer only to external macroecosystems, were found in the digestive canal.

Antibiotics - widely and repeatedly used means of treatment of people and various agricultural animals. It should be thought that in this case, even with an initially normal microflora, it can be partially or completely destroyed, and then replaced by a random one, as a result of which a variety of forms and degrees of disturbance can occur. However, often such disorders can begin much earlier due to unfavorable conditions arising from the non-optimal flora obtained at birth. Thus, already today there are questions about the ways of constructing and restoring the optimal microflora, that is, microecology, and endoecology of the organism.

It should be noted that, in all likelihood, in the future, maternity homes will have ideal bacterial polycultures. The latter and should (perhaps with feeding or otherwise) be vaccinated to children. It is not excluded that these polycultures will be collected from the most healthy mothers. It should also be identified whether the optimum polycultures in different countries are identical or should be different due to climatic and other characteristics of life of different groups of people.

trusted-source[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14]

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