Challenges doi: 10.15389/agrobiology.2015.1.3rus doi: 10.15389/agrobiology.2015.1.3eng BACTERIAL MICROORGANISMS ASSOCIATED WITH THE PLANT TISSUE CULTURE: IDENTIFICATION AND POSSIBLE ROLE (review) S.E. DUNAEVA1, Yu. <...> S. OSLEDKIN2 Morskaya, St. Petersburg, 190000 Russia, e-mail dunaevase@mail.ru; Podbel’skogo, St. Petersburg, 196608 Russia A b s t r a c t Effective sterilization of plant explants and antiseptics rules compliance do not exclude the presence of so-called covert (endophytic) bacteria in in vitro cultures. <...> But the role of these bacteria in tissues cultures has been not enough studied whereas it was related to the explants regeneration capacity and the possibility of animal and human cells transformation under in vitro cultivation. <...> Bacterial strains pathogenic to humans can be stably maintained in cultivated tissues and ex vitro plants. <...> The broadening of bacterial environments creates ecological and genetic risks leading to necessity of careful monitoring of endophytic communities in plants used as raw food and at use of in vitro technologies in practical plant growing and food production. <...> Two methods of identification are the most widespread: more available traditional one that does not allow detecting non-cultured forms (its base is the use of cultural and morphological characteristics as well as chemical and biochemical reactions) and molecular-genetic one. <...> At the second approach different 16S rRNA sequences are studied using metagenomic DNA and appropriate specific primers; these sequences have conserved sites identical for all prokaryotes and variable ones suitable for species specific regions identification. <...> Internal transcribed spacers (ITS) are being mainly used to distinguish the microorganisms at the species level and even at strains one. <...> Taxonomy of in vitro cultures’ bacterial endophytes indicates to their diversity and absence of specific composition as for cultures of plants belonging to different taxa as for different plant organs explants. <...> Among identified endophytic bacteria potentially useful for intact plants , pathogenic for humans, e.g. , , and and others were found as well as those , spp. <...> At in vitro plant cultivation durable symptomless bacterial presence is caused on the one hand by bacterial growth repression with factors accompanying plant explants cultivation (pH, temperature below bacterial optimum, activation of the defense mechanisms), and on the other <...>