The strains with antagonistic activity against indicator strains Pseudomonas aeruginosa, Proteus vulgaris, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumonia, Salmonella enterica were revealed among 58 Enterococcus strains isolated from gastrointestinal tract of long-livers. The influence of different components of MRS medium on the antagonistic effect was established. Antagonistic activity remained on the medium without glucose in 36% of strains, on the medium without tween 80--in 60% of strains, on the medium without sodium acetate and ammonium citric acid--in 65% of strains. The activity both for the lack of K2HPO4, MgSO4 and MnSO4, and in the absence of complex nitrogen sources (peptone, beef extract, yeast extract and hepatic extract) was shown in 76% of strains.