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Huma imtiaz
Khkula imtiaz
Nain Taara
Shaista Jabeen
Eiman Ismail
Mian Sami Ullah
Muhammad Salman
Aasma Siddiqui
Sadia Sardar
Farah Shireen


Probiotics, Antagonistic activity, pathogen, Lactobacillus and Bifidobacterium


The consumption of yogurt, containing probiotic microorganisms like Lactobacillus and Bifidobacterium, has been associated with numerous health benefits, including improved gastrointestinal health. In this study, we investigated the antagonistic activity of Lactobacillus and Bifidobacterium strains isolated from commercially available yogurt against pathogenic enteric bacteria.  This study investigated 50 samples of traditional Pakistani yogurt obtained from various regions of Peshawar, Khyber Pakhtunkhwa. Using MRS agar and standard microbiological techniques, Lactobacillus and Bifidobacterium strains were identified based on 16S rRNA sequencing. Antimicrobial activity was assessed using the well-diffusion method, with Gram staining confirming the Gram-positive nature of the isolates. Notably, Staphylococcus aureus exhibited positive tube coagulase, Enterococcus was catalase-positive, and Salmonella typhi tested positive in indole tests. Lactobacillus species were identified through PCR targeting the 16S rRNA gene. Bifidobacterium strains displayed significant activity against S. aureus (17mm inhibition zone) and moderate activity against Escherichia coli. Both Lactobacillus and Bifidobacterium demonstrated substantial antibacterial effects against Salmonella typhi, with lesser activity against Enterococcus. At 100 µg/ml concentration, both strains displayed potent antibacterial activity against S. aureus, followed by Salmonella typhi and Enterococcus, with moderate activity towards E. coli. Furthermore, phylogenetic analysis of the 16S rRNA gene sequences provided insights into the evolutionary relationships among the isolated strains. These findings underscore the potential of Lactobacillus and Bifidobacterium strains from traditional Pakistani yogurt as natural agents with antibacterial properties, suggesting their potential in promoting gastrointestinal health and combating enteric infections.

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