Lactobacillus gasseri ATCC 33323 suşunun probiyotik potansiyelinin araştırılması

Lactic acid bacteria (LAB) as a prime part of the human gut microbiota, have gained increasing interest as a research subject for characterization and the potential to be used as a probiotic candidate to promote human and animal health. The introduction of beneficial bacterial species into the gastrointestinal tract (GIT) may be a very appealing option to restore microbial equilibrium and prevent diseases given that the use of antibiotics among other forms of treatment, may change the composition and have an effect on the GIT microbiota. The aim of this study was to investigate and characterize the probiotic potential of the L. gasseri ATCC33323 strain. Probiotic features of the strain were screened using several tests, which included antimicrobial activity, acidifying activity, cell surface properties testing, tolerance to pH, bile salts, and phenol, antibiotic susceptibility, and anti-microbial activity tests including PCR and cloning. Results showed that L. gasseri ATCC33323 had an antagonistic effect against three pathogenic bacteria, S. aureus, E. coli, and L. monocytogenes RSKK. This strain also showed a high percentage of auto-aggregation with the highest value being 97.026% at the 5h mark, and high co-aggregation with all five pathogenic bacteria. L. gasseri ATCC33323 showed low acidifying activity, tolerance to varying pH points including pH 2, tolerance to bile with a growth rate of 50.6% in 0.3% concentration at the 4h mark, and resistance to differing phenol concentrations (0.1%, 0.2%, 0.3%, 0.4%) with 8.515log for 0.4% concentration at 24h mark, and it was susceptible to all four antibiotics which are ampicillin, kanamycin, erythromycin, and neomycin. In-silico analysis for bacteriocin screening results indicated the presence of a small protein obtained using specially designed primers, but further studies are required to identify bacteriocins in this strain. This study demonstrated that the L. gasseri ATCC33323 strain fulfilled the basic desired properties as a probiotic candidate and therefore has considerable potential to be used in the pharmaceutical and food industry.