Determination of virulence factors and decarboxylase actives of Enterococcus Faecium and Enteroccus Faecalis strains isolated from tulum cheese

In this study, the presence of 14 virulence genes (gelE, efaAfm, efaAfs, cpd, cob, ccf, cad, ace, espfm, espfs, agg, cylM, cylB and cylA) in 28 Enterococcus strains (21 Enterococcus faecium and 7 Enterococcus faecalis), isolated from Turkish Tulum cheese samples by Yogurtcu and Tuncer (2013), were investigated by polymerase chain reaction (PCR). Gelatinase and decarboxylase activities of these strains were also investigated by phenotypic methods. Investigation of virulence factors by PCR amplification revealed the presence of genes encoding for gelatinase (gelE), cell wall adhesions (efaAfm and efaAfs), sex pheromone (ccf), cell wall-associated protein (espfm and espfs) and aggregation substance (agg) in some Enterococcus strains. However, other presumed virulence genes (cpd, cob, cad, ace, cylM, cylB and cylA) in these strains were not detected. Enterococcal strains were found to contain virulence encoding genes which number ranging from 1 to 5 by PCR studies. Only one virulence factor was detected in E. faecalis NYE15, E. faecium NYE24, NYE45, NYE59 and NYE60 strains. On the other hand, E. faecalis NYE16, NYE46 and NYE48 strains were found to be contain the maximum virulence genes among tested enterococcal strains. PCR results showed that most frequently present virulence genes in enterococcal strains are ccf (85.7 %), efaAfm (75.0 %) and gelE (32.1 %). Four E. faecalis strains showed gelatinase activity on Todd-Hewitt Agar but, none of the E. faecium strains showed gelatinase activity. Phenotypic gelatinase test revealed the existence of apparently silent gelE gene. Silent gelE gene was identified in E. faecium NYE6, NYE23, NYE51, NYE52 and E. faecalis NYE16 strains. Lysine, ornithine and histidine were not decarboxylated by any enterococcal strains. However, tyrosine was decarboxylated by 92.9 % of the strains. The results of this study suggest that the use of Enterococcus strains as starter cultures to production of fermented foods requires careful safety evaluation.