[Structure-functional organization of bifidobacteria]

Regularities in the development of bifidobacterial populations were studied at cellular and subcellular levels. The population development of Bifidobacterium adolescentis MC-42 and B. bifidum no. 1 was shown to be accompanied by morphological cell differentiation. A scheme of morphological transformations of bifidobacterial cells in the developmental cycle of populations is proposed. Multiplication occurs via reversion of transitory rod-shaped and coccoid forms into repeatedly budding and dichotomously branching multiseptate filaments, which, under certain conditions, fragment with the formation of differentiated reproductive forms. The morphological differentiation of bifidobacterial cells in the developmental cycle of populations correlates with changes in the cell ultrastructure. Physiologically active proliferating cells contain an intracyto-plasmic mesosomal complex, chains of polyribosomes connected with membrane structures, and abundant polyphosphate and polyglucoside inclusions. Bifidobacterial populations are highly organized mycelium-type structures, whose integrity is provided for by the cohesion of the cells. Intercellular contacts are accomplished via cell wall fusion, capsules, and cordlike and globular structures.