In this study, we checked lactobacilli strains of human origin for their potential as probiotic. Samples were collected from oral mucosa of 16 healthy individuals, out of which twenty isolates were obtained and two of them were selected and identified as Lactobacillus plantarum (G1) and L. casei (G3). Both isolates exhibited antagonistic action towards pathogenic microorganisms such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Salmonella abony, and Clostridium sporogenes, but not on the growth of Candida albicans. The bacteriocin activity against Staphylococcus aureus ATCC 6358-P was shown only by L. plantarum G1. Moreover, the isolates G1 and G3 showed good viability in the acid gastric environment and in the gut environment containing bovine bile salts. The viability of G1 and G3 isolates in the gastrointestinal tract, and the adhesion to the intestinal mucosa were also confirmed in vivo. The biochemical tests of blood samples revealed lower levels of serum triglycerides and cholesterol, as well as reduced activity of alkaline phosphatase in all lactobacilli-treated Wistar rats, compared to control ones. No toxicity for NMRI Ham mice was observed. According to our experimental results, these findings imply that L. plantarum G1 and L. casei G3 could be characterized as potential probiotics

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The aim of this study was the partial characterization of the antimicrobial peptide bacteriocin G 2 produced by probiotic bacteria Lactobacillus plantarum G 2 , which was isolated from a clinical sample of a healthy person. Antimicrobial substance was secreted in the supernatant of an L. plantarum G 2 culture, and showed a diverse spectrum of antimicrobial activity of all the tested strains of the genera Lactobacillus and the pathogenic bacteria Staphylococcus aureus and Salmonella аbony. Isoelectric focusing revealed that bacteriocin G 2 is a cationic peptide (pI about 10) with a molecular mass of 2.2 kDa according to tricine-sodium dodecyl sulphate-polyacrylamide gel electrophoresis, SDS-PAGE. The antimicrobial activity of bacteriocin G 2 was diminished by the proteolytic action of trypsin and proteinase K. Bacteriocin G 2 preserved its biological activity in the temperature range 40-60 °C (15 min), which was lost at 80 °C. Bacteriocin G 2 was stable in the pH range 2-9, while treatment with 1 % Tween 80 and 1 % urea resulted in increased antimicrobial activity. The probiotic strain L. plantarum G 2 produces the antimicrobial substance proteinaceous in nature with bacteriocin characteristics. Bacteriocin production is one of the key properties of probiotic bacteria with clinical potential as antiinfective agents, which will increase the likelihood of its in vivo efficacy.

The aim of this study was to investigate the probiotic potential of bacteriocin-producing lactobacilli strain Lactobacillus plantarum G2 isolated from the vaginal mucus of healthy women. The antimicrobial effect of G2 was confirmed in the mixed culture with pathogenic Escherichia coli, Staphylococcus aureus, Salmonella abony and Pseudomonas aeruginosa, while bacteriocine activity was detected against S. aureus and S. abony only. The strain showed an excellent survival rate in low pH and in the presence of bile salts. The percentage of adhered cells of L. plantarum G2 to hexadecane was 63.85±2.0 indicating the intermediate hydrophobicity