Aim: To study morpho-physiologic characteristics of clinical biofilm-forming strains of Staphylococcus aureus and S. epidermidis suppressed by metabolites of lactobacilli, which produce bacteriocin-like substances.
Materials and methods: Two clinical biofilm-forming strains of S. aureus and one strain of S. epidermidis were used. Strains Lactobacillus plantarum L3 and L. fermentum 97 were used as producers of bactericidal metabolites. Ability of staphylococci to form biofilms was studied after their growth during 18 h at 37 degrees C in beef-extract broth with subsequent registration of biofilms attached to walls and bottom of polystyrene plate and stained by 0.1% alcohol solution of crystal violet. Ultrastructural changes in target cells were visualized by electron microscopy.
Results: Suppressive effect of lactobacilli metabolites on formation of biofilms by staphylococci was established. Ultrasructural changes, which characterize disorganization of vital processes such as mitosis, synthesis of DNA and peptidoglycan layer, were revealed in target cells. Formation and detachment of peptidoglycan globules from cell wall surface externally were noted.
Conclusion: Metabolites of lactobacilli are able to suppress formation of biofilms and induce ultrastructural changes in S. aureus and S. epidermidis, which lead to their destruction.