SAFETY ASSESSMENT OF ENTEROCOCCUS FAECIUM AND ENTEROCOCCUS FAECALIS STRAINS ISOLATED FROM TURKISH TULUM CHEESE

The aim of this study was to evaluate several genetic and phenotypic traits of clinical significance in 21 Enterococcus faecium and seven E.faecalis strains previously isolated from Turkish Tulum Cheese. Enterococcus strains were tested for the presence of 14 virulence genes and two vancomycin resistance genes by polymerase chain reaction (PCR). Biogenic amine production was also investigated by decarboxylase medium and PCR. Investigation of virulence factors by PCR amplification revealed the presence of genes encoding for gelatinase (gelE), cell wall adhesin (efaA(fm) and efaA(fs)), sex pheromone (ccf), cell wall-associated protein (esp(fm) and esp(fs)) and aggregation substance (agg). Other presumed virulence genes (cpd, cob, cad, ace, cylM, cylB and cylA) were not detected. At least one virulence gene was detected in all strains. The ccf (85.7%), efaA(fm) (75.0%) and gelE (32.1%) were detected most frequently present virulence genes in enterococcal strains. Phenotypic gelatinase testing revealed the existence of apparently silent gelE gene. None of the strains carried the vanA and vanB genes. Enterococcus strains did not decarboxylate histidine, lysine or ornithine, but the majority of strains (92.9%) produced tyramine from tyrosine. The tyrosine decarboxylase gene (tdc) was detected in all tyraminogenic strains. Practical ApplicationEnterococci are lactic acid bacteria that are important both in food and clinical microbiology. Enterococci species especially E.faecium and E.faecalis play an important role in the development of sensory characteristics of different traditional fermented foods such as dairy and meat products. On the other hand, E.faecium and E.faecalis are recognized as nosocomial pathogens. Results of this study indicated that E.faecium and E.faecalis strains isolated from Turkish Tulum Cheese carried some virulence genes and most of them produce tyramine. The findings of our study suggest that E.faecium and E.faecalis strains isolated from Turkish Tulum Cheese may be potential risk factors for consumer health. For this reason, use of Enterococcus strains as starter cultures requires thorough safety evaluation.