A pilot in vitro study of the antagonistic properties of Lactiplantibacillus plantarum isolates derived from the intestines of healthy adolescents in the Irkutsk region

Background. The growing antibiotic resistance; complicating the treatment of intestinal dysbiosis and related diseases; makes the development of probiotics for microbiota correction increasingly relevant. Lactiplantibacillus plantarum exhibits probiotic potential due to its antagonistic activity. Considering the strain-specific nature of this property; studying local isolates of L. plantarum is necessary for creating new; more effective probiotic preparations. The aim. To evaluate the in vitro antagonistic properties of five isolates of L. plantarum isolated from the intestines of healthy adolescents in the Irkutsk region against multidrug-resistant isolates of opportunistic bacteria and Escherichia coli. Materials and methods. Five isolates of L. plantarum 43p; 45p; 46p; 52p; and 57p were used; 25 multidrug-resistant isolates of opportunistic bacteria representing the species Enterobacter hormaechei; E. cloacae; Klebsiella pneumoniaе; K. oxytoca; K. variicola; Pseudomonas aeruginosa; Staphylococcus aureus; Citrobacter amalonaticus; and 23 isolates of E. coli with different characteristics. Antagonistic activity was evaluated by methods of perpendicular strokes and the well diffusion method. Results. L. plantarum isolates showed statistically significant variations in antagonistic activity; and these variations were also dependent on the testing method. A lot more activity was seen with the perpendicular strokes method. Statistically significant differences (p < 0.05) indicated that isolates 43p; 45p; and 46p were more effective antagonists than 52p and 57p; irrespective of the method. A marked antagonistic effect of L. plantarum isolates 43p; 45p; and 46p was observed against P. aeruginosa. Conclusion. This pilot study confirmed the strain-specific antagonistic potential of L. plantarum against multidrug-resistant opportunistic bacteria and E. coli; identifying L. plantarum isolates 43p; 45p; and 46p as the most promising candidates. These findings support the need for further screening of L. plantarum isolates; as well as other Lactobacillus species; cultured from the normal microbiota of healthy adolescents in the Irkutsk region. Furthermore; investigation of the mechanisms of antagonism is warranted to develop novel; effective probiotics based on local isolates.