Volume: 5, 2026
5th International PhD Students’ Conference at the University of Life Sciences in Lublin, Poland:
ENVIRONMENT – PLANT – ANIMAL – PRODUCT
Abstract number: A020
DOI: https://doi.org/10.24326/ICDSUPL5.A020
Published online: 22 April 2026
Evaluation of the antibacterial activity of bacteriocins and postbiotics produced by Lactococcus lactis and Enterococcus spp. against Staphylococcus aureus strains isolated from the milk of cows with mastitis
Joanna Kowalik1, Mariola Bochniarz1 and Andrea Lauková 2
1 Sub-Department of Veterinary Microbiology, Department of Preclinical Veterinary Sciences, Faculty of Veterinary Medicine, University of Life Sciences, 12 Akademicka St., 20-033 Lublin, Poland
2 Centre of Biosciences of the Slovak Academy of Sciences, Institute of Animal Physiology, Šoltésovej 4-6, 040 01 Košice, Slovakia
* Corresponding author: joanna.kowalik@up.edu.pl
Bacteriocins are peptides or proteins with antibacterial activity, naturally produced by bacteria to eliminate other, competing strains of microorganisms. They exhibit bactericidal or bacteriostatic activity. Their mechanism of action usually involves the formation of pores in the cell membrane of the target bacterium, leading to its lysis and death, the inhibition of cell wall synthesis, or the disruption of DNA replication processes.The aim of the studywas to evaluate the antibacterial activity of bacteriocins and postbiotics produced by Lactococcus lactis and Enterococcus spp. against strains of Staphylococcus aureus isolated from milk collected from Holstein-Friesian (HF) cows suffering from mastitis. The susceptibility of S. aureus strains to postbiotics was assessed using the ‘spot test’ method. The study used nisin, a bacteriocin produced by Lactococcus lactis subsp. lactis MCFB497, and the following postbiotics: PS/MK1/3 produced by the Lactococcus lactis MK1/3 strain isolated from raw goat’s milk, with GenBank accession number ON114093; PS/MK2/8 produced by Lactococcus lactis MK2/8, also isolated from raw goat’s milk (GenBank accession number PQ158272); PS/Ent 4231 produced by the rumen strain Enterococcus faecium CCM4231 and PS/Ent9296 produced by the strain Enterococcus faecium EF9296 used in the fermentation process.The postbiotic substances used were produced by strains isolated, characterised and studied at the Laboratory of Animal Microbiology, Centre for Biological Sciences of the Slovak Academy of Sciences, Institute of Animal Physiology in Košice, Slovakia.
Inhibitory activity was expressed in arbitrary units per millilitre (AU/ml) as the inverse of the highest twofold dilution of nisin and postbiotic substances that resulted in complete inhibition of the test strain. In the in vitro study, both the bacteriocin and the postbiotic substances produced by L. lactis exhibited high activity. The growth of all S. aureus strains was inhibited by nisin (800 AU/ml), PS/MK1/3 (100–200 AU/ml) and PS/MK2/8 (100–1600 AU/ml). In contrast, the postbiotic substances produced by E. faecium appeared to be ineffective. PS/Ent 4231 and PS/Ent 9296 did not show the ability to inhibit the growth of any of the tested S. aureus strains. The demonstrated research results indicate that bacteriocins constitute a promising alternative to antibiotics in the treatment of infections, including mastitis in cows.
Keywords: bacteriocins; cows; mastitis; Staphylococcus aureus
How to cite
Kowalik J., Bochniarz M., Lauková A., 2026. Evaluation of the antibacterial activity of bacteriocins and postbiotics produced by Lactococcus lactis and Enterococcus spp. against Staphylococcus aureus strains isolated from the milk of cows with mastitis. In: 5th International PhD Students’ Conference at the University of Life Sciences in Lublin, Poland: Environment – Plant – Animal – Product. https://doi.org/10.24326/ICDSUPL5.A020