16S rRNA based Molecular Characterization and Probiotics Potential of Streptococcus thermophilus Isolated from Nilli-Ravi Buffalo Feces: A Promising Candidate for Antibiotics Free Diary Production

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From many years, antibiotics have been mixed with feedstock of animals in order to kill harmful pathogens to improve the secretion of milk, the overall health of and the physiology of intestine to enhance the immunity of the host. However, the overuse and misuse of antibiotic is continuously leading to adverse consequences on animal nutrition and resulting in the emergence of the resistant pathogenic strains. In addition, it also affects the gut microflora in a way that animal become more prone to the infection. Due to these adverse effects on animal flora, it is important to look for substitutes of antibiotics with more useful benefits and fewer limitations. Recently different food additives, typically probiotics and pre-biotics have shown positive results on the growth and function of animal health, which are commercially available. It has also been proved that the probiotics play a vital role in enhancing the gastric microflora and improves animal health. The recent study was performed to isolate and identify probiotic bacteria from the faces of Nili-Ravi buffalo. In these studies, different parameters were used to isolate and identify Streptococcus thermophilus from buffalo faecal samples. Two strains of S. thermophilus with initial identity NCP-F06 and NCP-F13 were selected for their probiotic potential. Analysis of 16srRNA revealed that the isolate NCP-F06 was closely related to S. thermophilus (KLDS 3.0606) with a similarity of 89%. On the other hand, S. thermophilus (NCP-F13) showed a similarity of 94.74% to S. thermophilus (ST106). Similarly, Both the strains were examined for probiotic potential as well. The ability of this strain to survive at high temperature and show resistance to an acidic environment provides the clue for probiotic potential. Isolated strains showed antimicrobial activity against Staphylococcus aureus, Escherichia coli, Bacillus cereus and Listeria monocytogenes. Furthermore, S. thermophilus were sensitive against different types of antibiotics i.e. Ampicillin, Gentamycin, Kanamycin, and Chloramphenicol, however, both strains were found resistant to Streptomycin and Tetracycline. Besides these, both strains show amylolytic, lipolytic and proteolytic activity. My study concludes that S. thermophilus strains isolated from buffalo faecal samples are promising alternatives to antibiotics in the dairy feeding system.

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