Isolation and characterization of Lactobacillus spp. from different fecal samples that can be used as probiotic in fish

The objective of this thesis is to identify the Lactobacillus species isolated from different feces sources (fish, chicken and infant) to investigate some probiotic properties of isolated bacteria. Nine from fish, 17 from chicken and 24 from infant faeces, in 50 lactic acid bacteria (LAB) were isolated and of these, possible Lactobacillus 12 isolates were selected by considering Gram stain, catalase and cell morphologies. Two different techniques, API CH and MALDI-TOF MS were performed for identification of each isolates. In both techniques, isolates of BL1, BL2, BL3 and BL4 L. plantarum, TL2 and TL4 L. salivarius, YL2 L. rhamnosus and YL4 L. fermentum were identified as same species. Some probiotic properties (hydrophobicity, pH and bile salt tolerance) of selected strains (BL1, TL1, TL2, TL4 and YL2) isolated from feces was determined in vitro conditions. It was found out that all isolates possess the property of hydrophobicity. In the pH tolerance test, at the end of the 8th hour, the pH 5.0 absorbance value of BL1, TL4 and YL2 isolates was found to be significantly higher than pH 3.0 and pH 4.0 (p<0.05). It was determined that the absorbance value of TL2 and TL4 isolates was significantly higher than 0.3% in the bile salt conditions at a rate of 0.03% (p<0.05). It was determined that the highest absorbance value in YL2 isolate was in the control group and in 0.03% bile salt conditions (p>0.05). In conclusion, these two isolates (L. salivarius TL4 and L. rhamnosus YL2) were assessed for the strain possessing probiotic property according to the tests carried out in our research, and it was inferred that both – L. salivarius TL4 and L. rhamnosus YL2 could tolerate pH 5 and bile concentration of 0.03 %.