“Friend or foe” microbial recognition for selection criteria of oral cavity microsymbiont antagonists

Lactoflora viewed from associative symbiosis standpoint will allow for a comprehensive study of the various functions of these bacteria that determine the mechanisms of integrative interactions of microbiota with human body. The aim of the study: to search for effective antagonists targeting pathogens that cause oral cavity and periodontal inflammatory diseases based on “friend or foe” microbial recognition. The study involved 19 volunteers. Clinical material samples collected from patients were examined in the Laboratory of Microbiome, Regenerative Medicine and Cell Technologies at the Tyumen State Medical University. The smears from the inflammatory tissues of the oral mucosa were analyzed using standard bacteriological method. Biofilm formation was examined using the modified macrometric method. Metabolite output and “friend or foe” microbial recognition in the oral microsymbiocenosis were carried out according to the method, with its activity not including metabolites-related effect serving as a control. Microsymbionts-related biofilm formation as a universal physiological function was selected as a system-forming factor in microsymbiocenosis establishment. Lactobacillus spp. were chosen as the study object as normobiota and because they are found in both studied biotopes and can serve as a basis for new probiotics. Streptococcus spp., Staphylococcus aureus, Candida аlbicans were chosen as the associative microbiota as the etiological factors of inflammatory diseases in oral cavity and periodontal tissues. It was experimentally proven that the metabolic products of Lactobacillus spp. obtained from the oral cavity and pre-incubated with same biotope Streptococcus spp. (separately with each) significantly increased the activity of biofilm formation of the latter suggesting increased or preserved adaptive capabilities as an indicator of «relevant» microsymbionts for lactobacilli (p < 0.05). Metabolic products derived from Lactobacillus spp., obtained from two study biotopes, pre-incubated with metabolites of Staphylococcus aureus, Candida аlbicans, significantly reduced biofilm-forming activity of pathogens (p < 0.05). A decrease in film-forming activity is a marker of microsymbiont “foreignness” for lactobacilli during formation of bacterial-fungal associations. Lactobacillus spp., isolated from the gastrointestinal tract, are antagonists of Streptococcus mutans, Streptococcus mitis, Streptococcus uberis. And Lactobacillus spp., obtained from the oral cavity, on the contrary, are synergists of such pathogens. The data obtained open up avenues for understanding inter-microbial microsymbiont interactions and can be used both as diagnostic tools and for optimal selection of “candidates” in proposing new probiotics and synbiotics.