Determination of potential use as probiotic culture of genetically characterized human lactobacillus gasseri strains

In this study, six Lactobacillus gasseri MA strains previously isolated from the human breast milk were genetically identified by PCR (Polymerase Chain Reaction) based molecular identification method. The potency of MA strains as probiotic cultures was determined in in-vitro conditions using different parameters such as; resistance to low pH (2 and 3) values and different (0.3 and 1 %) bile concentrations, resistance to simulated gastric and intestinal fluids and hemolytic activities. Additionally, to check the potential of these strains for utilization in various processes sodium benzoate resistance properties and Alfa amylase enzyme activities have been determined. The auto-aggregation abilities of MA strains was recorded as 97-93 % while the coaggregation abilities with the test microorganisms varies between 36 % and 58 %. All the MA strains were found to be resistant against Amicacin, Gentamicin, Kanamicin, Nalidixic Acid and were found susceptible to antibiotics such as Ofloxacin, Amoxicillin, Ampicillin, Cloxacillin, Erythromycin and Penicillin. The antimicrobial activities studies of MA strains (used as test microorganisms) against various pathogenic microorganisms revealed inhibition zones values as; 1.87-14.29 mm for fifteen human-food pathogens, 1.66-11.22 mm for seven fish pathogens, and for two Candida strains 2.78-4.80 mm. For MA-2 strain the highest inhibition zones were recorded against Staphylococcus epidermidis ATCC 11228 human-food pathogen, Staphylococcus epidermidis ATCC 11228 fish pathogen, Candida albicans ATCC 10231 fungus. According to the DPPH method the antioxidant activities of MA strains were determined to be between 33.33 % and 54.93 % and the iron ion chelating activities ranged from 7.73 % to 26.88 %. The highest antioxidant activity among all MA strains was recorded for the MA-5 strain as a common result for both methods.