Identification of Enterococcus genus by MALDI-TOF-TOF-MS in some traditional cheeses

Within the scope of this study, isolation and identification of Enterococcus spp. from Antep, Urfa, Malatya and Maras cheeses, which are produced from raw milk by traditional methods and generally called as squeezed cheeses, were studied. Isolates whose pre-identifications made by Gram, katalaz and morphological tests were evaluated to be Enterococcus spp according to specifications. 84 isolates were then stored at -24°C after purity control. Identification on species level was done by Matrix-Assisted Laser Desorption Ionization-Time of Flight- Time of Flight-Mass Spectrometry (MALDI-TOF-TOF-MS) method. Out of 84 isolates, 32 E. faecalis, 31 E. faecium, 13 E. durans, 4 E. gallinarum, 3 E. casseliflavus and 1 E. thailandicus were identified. Sixty six of the identified 84 isolates were found at a confidence interval of 3.000 ≥ ID ≥ 2.300, and a correct identification of 78.57% was achieved on species level. On the other hand, there was a statistically significant difference between the Antep and Urfa cheeses in terms of the number of enterococci (p <0.05), whereas, no statistically significant difference was found between Malatya and Maraş cheeses. In addition, Antep cheeses were statistically found similar with Malatya and Maraş cheeses. When the cheese groups were evaluated according to chemical compositions, there was no significant difference in terms of dry matter content (p >0.05), whereas ash values of Maraş cheese group differ significantly from the other three groups (p<0.05). In terms of protein contents, Maraş and Urfa cheeses, in terms of fat content Antep and Maraş cheeses, in terms of salt content Maraş and Antep cheeses, in terms of total acidity Antep and Urfa cheeses were found statistically similar. Lastly, in terms of pH values, Antep cheeses were found to be statistically different from other 3 cheese groups (p<0.05 ).