engleski

The influence of the Zn ions on the survival rate of Francisella tularensis subsp. holarctica LVS strain in water

Francisella tularensis is a gram-negative facultative intracellular bacterium that resists harsh environment. The genus Francisella contains five species: F. tularensis, F. philomiragia, F. hispaniensis, F. noatunensis and F. novicida. Two subspecies of F. tularensis, tularensis (Type A) and holarctica (Type B) cause most cases of the illness in humans. An attenuated Type B strain, the live vaccine strain (LVS), was developed in the former Soviet Union and has been extensively used in research laboratories. Despite its name, LVS is not licensed for human vaccination due to safety and efficacy concerns. It has been shown that Francisella is able to survive in water and mud for more than a year. Few cases of tularemia reported in rural parts of Balkan and eastern countries were caused by the consumption of contaminated water, resulting in oropharyngeal form of the disease. The effective regulation of metal ion homeostasis is essential for the growth of microorganisms in the environment, and is associated with the ability of pathogenic bacteria to invade their hosts. To gain a better insight into zinc acquisition by Francisella we studied the effects of different concentrations of Zn ions (0.1 μM ; 0.8 μM ; 0.1 mM ; 0.5 mM and 1.0 mM) on the survival and replication of F. tularensis subsp. holarctica LVS strain in water by CFU. The concentrations of 0.1 mM, 0.5 mM and 1.0 mM of Zn ions decreased the growth of F. tularensis subsp. holarctica in water over time. Since the best survival of Francisella was achieved with concentration of 0.8 µM of Zn ions in water, we measured the aquisition of this ions by bacteria during 5 days.

Francisella; zinc; metal ions

nije evidentirano