Molecular identification and diversity of enterococci isolated from Slovak Bryndza cheese

Abstract

Three hundred and eight presumed enterococcal isolates were recovered from Bryndza, a soft sheep milk cheese. The cheese samples were obtained from five different commercial distributors in Slovakia and were taken at three different seasonal intervals. All isolates were identified to the species level using genotypic tools. Species-specific PCR using ddl genes highlighted the predominance of Enterococcus faecium (176 isolates) and assigned 50 isolates to the species Enterococcus faecalis. The remaining 82 isolates were classified using repetitive element sequence-based polymerase chain reaction (PCR) with primer (GTG)₅–(GTG)₅-PCR, in combination with phenylalanyl-tRNA synthase gene (pheS) sequence analysis and by whole-cell protein analysis (SDS-PAGE). These strains were identified as Enterococcus durans (59 strains), Enterococcus italicus (8 strains), Enterococcus casseliflavus (3 strains), Enterococcus gallinarum (3 strains), Enterococcus hirae (1 strain), and 8 strains were members of the species Lactococcus lactis. Of the seven enterococcal species isolated, three of them, E. durans, E. faecalis and E. faecium were present in all samples studied, with E. faecium as the predominant one. The precise identification of enterococci in Bryndza cheese is an essential step in the process of evaluation of their functional properties which will be further studied and assessed.