For a long time, the strains Bifidobacterium bifidum 1, Bifidobacterium bifidum 791, and Bifidobacterium longum 379 have been successfully used as probiotic producers; the conclusions about the possibility of their use, their role and functions in the human body were made empirically based on indirect signs. At present, high-tech equipment and modern research methods allow to conduct a complete study of the properties and characterization of strains; it is regulated by modern regulatory documents. In our work we applied the classical bacteriological method, MALDI TOF mass spectrometry method, NGS whole genome sequencing. The analysis of 27 clones of the strains revealed that they have typical morphological properties and stable biochemical profiles; the lists of ionized protein masses (so-called "strain markers") were determined. The whole genomes of strains deposited by us in GenBank in 2015-2017 were analyzed for the first time; we found that they do not contain pathogenicity genes, integrated plasmids, determinants of transmissible antibiotic resistance, and belong to phylogenetic clusters formed by probiotic-producing strains. It was shown that B. bifidum 1 and B. bifidum 791 have a pronounced ability to consume glycans of intestinal mucus, while B. longum 379 can efficiently consume plant glycans. The genomes of B. bifidum 791 and B. longum 379 strains contain genes for the synthesis of the most important neurometabolites of tryptophan and folic acid; the genome of B. bifidum 791 strain contains genes for the synthesis of lasso peptide and flavucin, class I lantibiotics with a wide spectrum of antimicrobial and antiviral activity.