Safety Assessment of <i><scp>E</scp>nterococcus faecium</i> and <i><scp>E</scp>nterococcus faecalis</i> Strains Isolated from <scp>T</scp>urkish <scp>T</scp>ulum <scp>C</scp>heese

Abstract

Abstract The aim of this study was to evaluate several genetic and phenotypic traits of clinical significance in 21 E nterococcus faecium and seven E. faecalis strains previously isolated from T urkish T ulum C heese. E nterococcus 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. E nterococcus 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 Application Enterococci 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 T urkish T ulum C heese 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 T urkish T ulum C heese may be potential risk factors for consumer health. For this reason, use of E nterococcus strains as starter cultures requires thorough safety evaluation.