Purpose: The present study aimed the characterization of the virulence potential and antibiotic resistance of bacteriocinogenic Enterococcus strains isolated from raw goat milk.
Methods: Thirty-two Enterococcus isolates obtained from raw goat milk previously identified by PCR and capable to produce bacteriocins were selected and subjected to rep-PCR for fingerprinting. Fourteen strains were selected and tested for the presence of virulence genes (gelatinase, hyaluronidase, aggregation substance, surface protein, cytolisin, endocarditic antigen, adhesion and vancomycin resistance) using PCR and for antibiotic resistance using Etest™ (vancomycin, chloramphenicol, ampicillin, rifampicin and gentamicin). Finally, the 32 isolates were subjected to phenotypic tests to identify the gelatinase and lipase production, and desoxyribonuclease and haemolytic activity.
Results: All tested strains presented at least one of the investigated virulence genes. None of them contained gene for hyaluronidase and vancomycin resistance. In counterpart, all strains were positive for enterococal surface protein gene. All strains were sensitive to the antibiotics vancomycin, chloramphenicol, ampicillin and rifampicin, and three strains were resistant to gentamicin. Nine strains presented α-haemolytic activity, and one was capable to produce lipase. Three strains that presented positive results for the gelatinase gene were also capable to produce it.
Significance: The study demonstrated that Enterococcus isolated from raw goat milk may present virulence genes and antibiotic resistance. Despite no reported foodborne infections by Enterococcus, these strains can transfer virulence genes to other pathogenic microorganisms. Therefore, is important to test these characteristics before using the strains for biopreservation of foods.