Isolation and characterization of probiotic bacteria isolated from cow milk

BACKGROUND AND OBJECTIVESProbiotics are live beneficial bacteria with positive effects on the host's health. These bacteria can eliminate harmful pathogens in the intestine and maintaining the balance of intestinal microbial flora. For example, Lactobacilli acidophilus are "friendly" bacteria that normally live in our digestive, urinary and genital systems without causing disease. Some of the functions of these bacteria include antimicrobial activity, improving body metabolism, anti-diarrheal properties, and improving inflammatory bowel diseases. Accordingly, the aim of this research was to isolate and identify of probiotic bacteria from milk samples.MATERIALS AND METHODSSamples of cow milk were collected from Kerman city (south east of Iran) during spring ۲۰۲۳. Samples in Falcon tubes in ice-box were delivered to the research lab. Milk samples serially diluted from۱۰-۱ to ۱۰-۶. ۱۰۰ μL of different were inoculated on MRS agar medium. Pured probiotic bacteria were characterized by different standard tests such as Gram staining, catalase, indole production, motility, and determination of fermentation patterns of sorbitol, arabinose, glucose, lactose, galactose, sucrose, and mannitol.RESULTS AND DISCUSSIONMRS Agar was a medium for the cultivation and enumeration of Lactobacillus spp. and most lactic acid bacteria. Accordingly, out of ۳۰ milk samples, ۵ probiotic bacteria were isolated from Lactobacilli MRS Agar. Based on biochemical and diagnostic tests, all isolated strains were Gram-positive and catalase-negative. Four isolates were bacilli and the remaining one was coccus. Examination of indole production were negative, ۴ isolates were non-motile. Three strains were able to ferment arabinose, and ۲ ones were able to ferment sorbitol. None of them could ferment sucrose, galactose, or lactose. Additionally, all ۵ bacteria were able to ferment glucose.CONCLUSIONAs consumers require foods not only providing energy but also with the ability to improve and enhance their health, probiotic dairy products are in a special importance. Above mentioned isolates may be behave as good candidate probiotics, but further in vitro and in vivo studies on these strains are still required and ongoing .

کلیدواژه ها:

Probiotics ، milk ، isolation and chracterization