Faecal Enterococcus hirae from domestic ducks were studied for their bioactivity to select bioactive strain for more detailed study with its probable use in poultry and also to bring novelty in basic research. After defecation, faeces (n=23, faecal mixture of 40 ducks) were sampled from domestic ducks in eastern Slovakia; birds were aged from eight to 14 weeks. E. hirae strains were identified using Matrix-assisted laser desorption/ionization time-of flight mass spectrometry with a highly probable species identification score (2.300-3.000) or a secure genus identification/ /probable species identification score (2.000-2.299), confirmed by polymerase chain reaction and phenotypization in accordance with the properties for the type strain E. hirae ATCC 9790. Strains were hemolysis negative (γ-hemolysis), and did not have active enzyme stimulating disorders. Enterocin genes were detected in three strains out of seven. Three out of four Enterocin genes were detected in Kč1/b (Ent A, P, L50A); the most frequently detected was the Ent P gene. The strains inhibited indicator strains E. faecalis, listeriae, but also Escherichia coli and Buttiauxiella strains. Lactic-acid producing E. hirae were mostly susceptible to antibiotics. Based on parameter evaluation, E. hirae Kč1/b, Kč6 can be additionally studied to select the type of bioactive substance.

Enterococcus hirae belongs in the Enterococcus faecium group within the genus Enterococcus. This species occurs naturally in the environment, commensally in the alimentary tracts of animals, and pathologically for example in humans with urinary infections. Some strains of E. hirae possess virulence factors, including biofilm formation. Biofilm growth protects bacteria against host de- fences; biofilm can be a source of persistent infection. Testing bacterial strains for their ability to form biofilm might therefore facilitate their treatment or prevention. This study focuses on bio- film formation by E. hirae strains derived from various animals. This kind of testing has never been done before. A total of 64 identified E. hirae from laying hens, ducks, pheasants, ostriches, rabbits, horses and a goat were tested by means of three methods; using Congo red agar, the tube method and microtiter plate agar. The majority of strains were found to form biofilm. 62.5% of strains were biofilm-forming, four categorized as highly positive (OD570 ≥1); most strains were low-grade biofilm positive (0.1 ≤ OD 570 < 1). Related to poultry, 55 E. hirae strains were tested nd found to produce biofilm; 24 strains did not form biofilm, 31 strains were biofilm-forming; 27 strains showed low-grade biofilm formation, and four strains were highly biofilm-forming. Four strains from hens and ostriches reached the highest OD570 values, more than 0.500. Rabbit-derived E. hirae strains as well as strains isolated from horses and the goat were low-grade bio- film-forming. Microtiter plate assay proved to be the best tool for testing the in vitro biofilm for- mation capacity of E. hirae strains from different species of animals.