Dissociation of Mycobacterium bovis: Morphology, Biological Properties and Lipids

Abstract

The article presents the results of investigations concerning the cleavage of avirulent cells from the virulent epizootic strain Mycobacterium bovis (M. bovis) during the 20 month storage at low positive temperatures (2-3°C). It was preceded by a 116-fold reinoculation of the suspension of the virulent culture into a dense nutrient medium. Mycobacteria of the detected colonies have acquired new features and properties. It was noted that in the second and subsequent generations, mycobacteria appeared in the form of non-acid resistant grains and short rod-shaped bacteria and L-forms of the protoplastic (spheroplastic) type. The change in morphology was accompanied by the emergence in mycobacteria of the ability to be grown on chemically simple nutrient media. Different morphological forms of mycobacteria were found in the elective dense nutrient medium at 3°C and 37°C cultivation: at 3°C irrespective of the initial morphological forms, non-acid-resistant short rod-shaped bacteria and grains were generated in dynamics; at 37°C-L-shaped protoplastic (spheroplastic) type and elementary small bodies. The appearance of the latter in culture has changed the nature of its growth. It is shown that qualitative processes of morphological forms of the biological cycle of mycobacteria occur on the background of quantitative changes in the chemical composition, in particular lipids. The content of total lipids decreased, at the stability of the quality of the fractions of total lipids. Differences in the ratio of unsaturated to saturated fatty acids in pathogenic and non-pathogenic mycobacteria have been established. Long-chain acids with a content of 26-27 carbon atoms, regardless of the temperature of cultivation, disappeared in the dissociative forms. The biological cycle of the development of dissociative M. bovis at different temperatures of cultivation with properties distinct from the parent strain, characterizes the wider possibilities of the investigated microorganism as it is known today.

Influence of Sitophilus oryzae on biological properties of Mycobacterium bovis

“…However, despite the absence of visible clinical and anatomical pathology changes in guinea pigs, it was possible to isolate mycobacteria from their internal organs. The obtained data do not contradict the study of Tkachenko et al (2020), which describes the absence of an infectious process in laboratory animals infected with dissociative forms of M. bovis after long-term storage. As is known, mycobacteria that have lost their virulent properties can survive and replicate in the macroorganism without causing immunopathological processes.…”

“…A typical example of the variability of the causative agent of tuberculosis is the dissociation of mycobacteria. Dissociative forms of M. bovis are characterized by a change in the metabolic processes of the bacterial cell, which contributes to a wide range of survival of the microbe in the external environment (Tkachenko et al, 2020).…”

Особливості Інфікування Жуків Мікобактеріями Та Їх Вплив На Життєздатність Збудника

“…Здатність мікобактерій до адаптації у навколишньому середовищі, мінливості та існування в різних морфологічних формах ускладнюють діагностику туберкульозу [5,6]. Крім того, макроорганізм може переносити збудника інфекції латентно, без прояву клінічних ознак.…”

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“…A typical example of the variability of the causative agent of tuberculosis is the dissociation of mycobacteria. Dissociative forms of M. bovis are characterized by a change in the metabolic processes of the bacterial cell, which contributes to a wide range of survival of the microbe in the external environment (Tkachenko et al, 2020). As a result of adaptation to the conditions of existence, the pathogen has an expansive range of biological and mechanical vectors.…”