Isolation and evaluation of some probiotic features of enterococci from Jersey cow milk and its fermented products in Qom

Enterococci are among the lactic acid bacteria with probiotic potential which are found in dairy products and especially in fermented products. The study aimed to isolate enterococci from raw milk of Jersey cows and its fermented products as well as to determine some probiotic properties of the isolates. Five specimens from each of raw milk, buttermilk, yogurt, cheese, and butter were obtained. Twelve isolates of Enterococcus faecium, Enterococcus avium, and Enterococcus faecalis were isolated. The antimicrobial effects of the isolates were investigated on indicator microorganisms. All isolates had an inhibitory effect on these microorganisms. Escherichia coli was more sensitive than the others. Pseudomonas aeruginosa and Listeria ivanovii followed, and the lowest susceptibility was observed in Listeria monocytogenes, Bacillus cereus, and Klebsiella pneumoniae, respectively. Overall, gram-negative microorganisms were significantly more sensitive than gram-positive microorganisms (p≤0.05). In the study of resistance of isolates in culture medium containing 0.3% bile, out of 12 isolates obtained from the tested samples, two isolates of E. avium (40%), three E. faecalis isolates (100%), and one E. faecium (20%) were found to be resistant. Amongst, one isolate of E. avium was resistant to acidic conditions. In general, milk and fermented products can be considered rich sources of Enterococcus species, a small number of which are resistant to the human gastrointestinal tract environment. Of course, these isolates must be further evaluated for safety.