With age, the number of bacterial cells in the intestine gradually reaches 100 trillion, which exceeds the number of the body’s own cells in an adult by 10 times. At the same time, due to the small size of bacteria, the entire microbiota weighs up to 2 kg and fits in the large intestine.
About 60% of the contents of the rectum are microorganisms, the colonies of which grow on the fibers of plant food (fiber), using them as food and a skeleton, thereby forming a lumpy consistency of feces. Despite the significant number of bacteria, their interaction with the human body has long been considered by scientists strictly within the framework of commensalism, in which the microorganism benefits from the relationship, and the macroorganism receives neither benefit nor harm. However, with the development of genotyping methods, the concept of microbiota has changed significantly.
It was found that the species diversity of microbiota reaches 300-700 species of microorganisms, and their total genome consists of 10 million genes, which is 300 times greater than the human genome. Such a summation of the genes of the microbiome and a comparison of their number with that in humans is not just a catchword. Many bacterial genes functionally complement the human nuclear genome, and the interspecies interaction of microorganisms is so close that some species literally cannot live without each other.
Recent discoveries in this direction have made it possible to talk about the mutually beneficial relationship between man and the microbiota, and the set of its genes is called the microbiome or the third human genome. To illustrate, I will give a specific example.Поділитися цим: