Selection and characterization of potential probiotic <italic>Lactobacilli spp</italic> isolated from chicken feces may be used as a potent antibacterial agent

Abstract

<italic>Lactobacillus</italic> strains commonly used as probiotics which possess some properties such as resistance to gastric acidity and bile salts, production of antimicrobial compounds, the ability to modulate immune responses, and adhesion to gut tissues. This study aimed to isolate, identify, production and characterization of the probiotic strains. Total of 10 digestive tracts of chickens fed without antibiotics for presence of <italic>Lactobacillus spp</italic> was evaluated. All isolates were grown with different conditions like effect of temperature, pH, pepsine, bile, sodium chloride tolerance, aggregation, adhesion and antibiotic resistance test tested and then antibacterial activity was determined.In this study, 34 lactic acid bacteria were investigated as putative probiotic candidates. Based on the molecular identification using 16S rDNA sequencing the isolates belonged to <italic>Lactobacillus</italic> species. The strains showed potent antibacterial activity. The results on acid tolerance showed that all the strains tested survived at pH 2.0 to 5.5. <italic>L. agilis</italic> strain M18, <italic>L. salivarius</italic> strain M10, <italic>L.vaginalis</italic> strains M8 and M19, and <italic>L. crispatus</italic> strains Or2 and M10 showed the lowest sensitivity to pepsine. All the studied Lactobacillus strains were able to grow at both 15 and 45°C . Five Lactobacillus strains adhered well to the Caco-2 cells. The result of antibiotic resistance test of 34 lactic acid bacteria showed that most of them were resistant or intermediate. Based on 34 <italic>Lactobacillus</italic> strains, <italic>L. vaginalis</italic> strain M8 and <italic>L. reuteri</italic> strain M6 were selected for the further in vivo assays and possible eventual use as prophylactic and therapeutic agent.