SURVIVAL OF BURKHOLDERIA PSEUDOMALLEI IN CELLS OF TETRAHYMENA PYRIFORMIS CILIATE INFUZORIAN: EFFECT ON TETRAHYMENA ENCYSTMENT ACTIVITY

Objective of the study was to model the interaction of Burkholderia pseudomallei with Tetrahymena pyriformis in vitro and investigate the changes in the population composition of the protozoa when co-cultured with a microorganism.Materials and methods. B. pseudomallei 110, C141, 57576, 107 strains differing in virulence for BALB/c mice were used. The axenic culture of T. pyriformis was incubated with microorganisms in 100 to 1 ratio, at 28 °C, in LB. Samples of co-cultures were examined using light microscopy, by counting the number of trophozoites and cysts in the population. Dynamics of multiplication of B. pseudomallei cultures associated with T. pyriformis was determined through seeding bacteria on a dense nutrient medium to count the grown colonies.Results and conclusions. B. pseudomallei in association with T. pyriformis is ingested by protozoan cells; it multiplies in them and stimulates protozoa encystment. Hereby virulent strain B. pseudomallei 110 induces encystment of T. pyriformis on days 2–4 and complete cell destruction within 7–8 days. Avirulent strain, B. pseudomallei 107, induces full encystment on day 7; significant part of the cysts remains intact on day10. Dynamics of B. pseudomallei growth, co-cultured with T. pyriformis is characterized on day 1 by distinct decrease in the number of viable bacterial cells and increase in it within following 24 hours. Bacteria concentration curves depend on the virulence of the strain: maximum level of B. pseudomallei 110 replication is observed after 48 hours, while that of B. pseudomallei 107 – not less than after 7–8 days

Burkholderia pseudomallei Morphotypes that Form in vitro under Stress Conditions

Objective of the study was to determine diversity of the morphotypes formed in vitro from the initial morphological variant of B. pseudomallei 110 under stressful conditions and to study some phenotypic characteristics of them. Materials and methods. Virulent strain Burkholderia pseudomallei 110 of Australian serotype was used. Burkholderia cultures were added to the axenic culture of Tetrahymena pyriformis in LB broth and sterile river water in the ratio of 100: 1 and incubated at 28 °C; the passage of monocultures and cultures in protozoa cells was repeated at intervals of 3–4 days. Morphotypes were identified on Ashdown’s medium after cultivation for 3–4 days at 32 °C, photographs were analyzed based on classification of Chantratita et al. In all morphotypes the activity of extracellular enzymes and virulence were determined on the model of golden hamsters. Results and conclusions. Seven B. pseudomallei 110 colony morphotypes were identified. Four of them with characteristics of I, III, IV and VII morphotypes, described by Chantratita et al., were named Chl (Chantratita like variant). The study of morphotypes in different samples revealed a variation in them, depending on the culture medium (LB broth or water), and their different ratios in individual samples. The greatest number of morphological variants (4 out of 7) was formed during the passage of the monocultures of B. pseudomallei 110 in LB broth; in water the initial culture was almost entirely (95 %) transformed into morphotype I Chl. Under other conditions of cultivation the dominant V morphotype was formed, and in the presence of protozoa it was combined predominantly with I Chl. Morphotypes differed in the production of extracellular enzymes, motility and reduced virulence

BIOLOGICAL SAFETY: ANALYSIS THE CONTEMPORARY STATE OF THE SYSTEM OF TRAINING SPECIALISTS IN RUSSIAN FEDERATION

The review expounds the main content issues of biological safety in the modern period. Theproblems of postgraduate education in the field of biological safety through professional retraining and advanced training programs, as well as training of highly qualified specialists were discussed. The need to form a separate specialty “Biological Safety”for specialists in medical and biological profiles was noted

Phenotypic Peculiarities of Pathogenic <i>Burkholderia</i> Mutants Resistant to Fluoroquinolones and Cephalosporins

Examined were phenotypic peculiarities of mutants of Burkholderia phylogenetically-related pathogenic species (B. pseudomallei, B. mallei, B. cepacia) resistant to fluoroquinolones and cephalosporins. It was shown that strains with PfxR (OfxR), CfzR markers acquire high multi-drug resistance to antibiotics of different classes. Strain resistance changes under blocking influence of verapamil - inhibitor of calcium membrane channels. Mutant strains differ in production of extracellular enzymes (proteases, lecithinase, lipase) and virulence

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

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