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. 

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