Antagonistic Activity of Lactobacilli against Collection Strains of Escherichia coli

This research featured mesophilic lactobacilli Lacticaseibacillus casei 738-11, Lacticaseibacillus paracasei K-6, Lacticaseibacillus rhamnosus P, Limosilactobacillus fermentum 39, and Lactiplantibacillus plantarum 28 and 37 from the microbial culture collection of the All-Russian Scientific Research Institute of Butter and Cheese Production, Uglich. The research objective was to measure the activity of these cultures against Escherichia coli. The inhibitory effect depended on the strain. The inhibition areas obtained by the method of perpendicular strokes were 9.3 mm for L. casei 738-11, 11.3 mm for L. paracasei K-6, 10.3 mm for L. rhamnosus P, 12 mm for L. plantarum 28, and 11.7 mm for L. plantarum 37. The lactobacilli had no effect on E. coli during the first 24 h of co-culturing in milk; however, they accelerated the extinction. The highest rate of E. coli extinction was observed in the sample with L. rhamnosus P: the count of E. coli cells decreased by 4 after 48 h and by 6.5 after 72 h. The experiment revealed no correlation between the acid formation rate and the antagonistic activity of lactobacilli.