An overview of the present status and prospects of gnotobiology along with a role of normal microflora studied using laboratory animals with controlled microflora (gnotobiotes) is presented. The principal elements of gnotobiotechnology as well as possibilities of its using in both experimental and clinical investigations are analyzed. A multifaceted role of normal microflora in the host physiology and pathology prejudge the increasing importance of gnotiological models in various fields of biology and medicine, such as the development of new generations probiotics. An assessment and characteristics of selected microbial strains, host-microbe interactions etc. An organization of further complex gnotobiotic research is of prospective value.

Bacterial translocation (BT) is both pathology and physiology phenomenon. In healthy newborns it accompanies the process of establishing the autochthonous intestinal microbiota and the host microbiome. In immunodeficiency it can be an aethio-pathogenetic link and a manifestation of infection or septic complications. The host colonization resistance to exogenous microbic colonizers is provided by gastrointestinal microbiota in