Evaluating the antimicrobial effect of postbiotic extract from Lactobacillus casei on Escherichia coli in commercial sterilized milk

The antimicrobial effect postbiotic extant of Lactobacillus casei was evaluated against Escherichia coli by well propagation method and growth inhibition zone diameter was measured. The selected concentration of the postbiotic extract of L. casei was added to milk containing E. coli, followed by evaluating the changes in colony number and pH during storage (1 and 5) days at 4°C then compared with control milk. The largest growth inhibition zone was formed at a concentration of 800 µl/ml against E. coli. Also, the counts of E. coli decreased on days 1 and 5 in the evaluated milk containing postbiotic (p≤ 0.05). The pH of milk containing postbiotic was 6.5-6.8 (p≤ 0.05). The results showed that the postbiotics of L. casei inhibited the growth of E. coli in milk containing.