Switching of Burkholderia pseudomallei colony morphotypes in stationary condition and in the organism of experimental animals

Abstract

Aim. Сharacterization of Burkholderia pseudomallei 110 morphotypes, obtained under various cultivation conditions, studying phenotypic characteristics and switching of colony morphology after removal of stress and in the organism of experimental animals. Materials and methods. Morphotypes were induced by passage of B. pseudomallei 110 in LB, sterile river water and in Tetrahymena pyriformis cells, identified on Ashdown medium, classified according to Chantratita et al., some phenotypic characteristics have been determined. Cultures of morphotypes were stored for 6-10 months in 0,4% Nutrient agar under liquid petrolatun and colony morphology was analyzed. Results. Seven morphotypes of colonies were identified and designated I Chl, II, III Chl, IV Chl, V, VI, and VII Chl. The variability of morphotypes and their ratio depended on cultivation conditions. Morphotypes were distinguished by the activity of extracellular enzymes, mobility, characterized by increase of porin proteins production, variation in protein mass-spectrums, and decrease of virulence. From animals infected with all morphotypes was obtained I Chl morphotype; during storage, all cultures acquired the structure of morphotype VI (VII Chl) of the original strain, similar enzymatic activity and partially restored virulence. Conclusion. The morphotype VI (VII Chl) B. pseudomallei 110 under stress conditions gives rise to 5 other morphotypes that in the animals are switched to the morphotype I Chl; after removal of the stressful effect they are reverted to the initial morphological variant and its phenotypic properties are restored.