Evaluation of Stimulating Effect of Biogenic Amine Serotonin on Capsule-Like Substance of Francisella Tularensis

Abstract

Aim. Evaluate the effect of serotonin on morphometric and topographic characteristics of cells of vaccine strain of F. tularensis 15 NIIEG (Cap+) and its non-capsule variant F. tularensis KM-9 (Cap ). Materials and methods. Analysis was carried out by methods of densitomorphometry and atomic-force microscopy. Results. Cultivation of F. tularensis 15 NIIEG (Cap+) in FT agar has shown that in the presence of serotonin the thickness of capsule-like substance, surrounding bacterial cells, has increased on average 3 times and was 95.1±0.56 nm against 31.7±0.18 nm in control (without serotonin). During similar cultivation of F. tularensis KM-9 (Cap") such phenomenon was noted detected. Capsule-like substance of tularemia microbe was established to play an important role in biofilm formation. Conclusion. The data obtained prove an importance of phenotype of tularemia microbe and allow to assume a special role of serotonin in the processes of formation of biofilm community, in which the bacteria are protected from damaging factors of the environment.