The role of filterable forms in bacterial variability Heredity and variability of plants, animals and microorganisms

Zhitova, E.I.

Akad Nauk Sssr Moscow : 294-298


Accession: 025923529

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The filterable forms (FF) are defined as a state of bacterial existence following natural disintegration of the bacterial cells or their destruction by artificial means. From the regenerated FF the following types were recovered: cultures showing incomplete development of the cells (differentiated from the parent strain by both their morphology and their nutritional requirements) and cultures exhibiting complete development of the cells (but still differing in some respects from the parent strains). The remarkable character of the poorly growing cultures regenerated from FF consists in the lack of differentiation exhibited in common properties, notwithstanding the use of different species. This indicates a common and identical mechanism of formation, assuming that while FF are formed, the species-specific enzymatic systems - phylogenetically the more recently established - were impaired, while those fulfilling important, vital functions were preserved. Upon subsequent passage on nutrient media and later in animals, they may perish or revert to the original species, or establish variant strains. Cultures identical with the original parent strains are seldom recovered; usually cultures from filtrates exhibit changed properties classified as follows: changed antigenic properties, changed biochemical properties (reduced activity or inactivity towards carbohydrates and alcohols) and pigment-forming organisms differing in certain properties from the parent strain. The strains are usually nonvirulent, nontoxic and stable in their properties. Reversion to their initial specific properties was rarely achieved. The main trend in the course of variability upon regeneration of the FF is toward a saprophytic mode of life. The FF constitute the initial material for the formation of strains with changed properties.