Relationships of microorganisms and plants represent a fundamental scientific problem . This is due to the fact that the scope of this relationship is very wide - from pathogenesis to symbiosis. The mechanism of interaction between microorganisms and plants is a subject of particular interest. Studies in recent decades have shown that nodule bacteria and phytopathogenic microorganisms have a complex , multi-step process of interaction with plants, ending in the first case with the formation of nodules on the roots of leguminous plants, where localized nodule bacteria and the process of fixation of molecular nitrogen , and in the second - occurrence of the source of infection and disease plants. Previously it was thought that the internal tissues of plants almost sterile and can be inhabited only by phytopathogenic microorganisms , with the defeat of the plant. However , in further studies it was found that the roots and stems of the plants have inside a large number of various microorganisms of the genera Bacillus, Pseudomonas, Klebsiella, Enterobacter. They are called endophytic bacteria , ie bacteria that live in the inner tissues of plants without causing them harm. Further investigation showed the specificity of endophytic bacteria with various plants. Therefore, the use of endophytic bacteria to create microbiological agents allow more fully realize the biotechnology potential of both plants and microorganisms. Claimed area of research is new to Russia, and is being developed in a number of industrialized countries, the EU and the United States ("Molecular Microbial Ecology of the Rhizosphere"; FJ De Bruijn [Ed]; Wiley / Blackwell; 1328 p.). Results of the research will be published in leading international and Russian periodicals and included in the specialized courses for undergraduate and graduate students.