# Microbiota \"Fingerprint\" of Greek Feta Cheese through Ripening
## 4 Discussion
faecalis_, for example, exerts higher proteolytic and lipolytic activity than _E. ficeum_ and _E. durans_. According to [PERSON] et al. [49], enterococci from cheese can survive at low pH values and at exposure to high concentration of bile salts and some strains such as _E. ficeum_, _E. faecalis_, and _E. durans_ are the main producers of enterocins. Some of these bacteriocins can be grouped with typical bacteriocins produced by LABs, providing opportunities for more effective control of pathogenic bacteria [50]. Four staphylococcal species have been detected in Feta samples, all belonging to the co-agulase negative staphylococci (CoNS) group. Three of them were present only in the six months ripened-cheese, while _S. saprophyticus_ were detected only in three months ripened-cheese (Table 3). Usually, these bacteria are spoilage, originating from the ripening chamber or the packaging device and most probably could be a source of contamination of the produced cheese [51]. The Regulation does not refer to the occurrence of CoNS species in food. Food is often a reservoir of these bacteria, and their common occurrence results primarily from resistance to unfavorable environmental conditions during the production processes, food storage, and high adaptation abilities of those micro-organisms [52]. It is worth mentioning that some CoNs strains such as _Staphylococcus quorum_ are frequently involved in cheese ripening while specific strains of this microorganism could be used as a starter culture for smear ripened cheees. Other staphylococci such as _S. saprophyticus_, _S. lentus_, _S. sciuri_, and _S. succinus subsp. casei_ can also be involved in dairy fermentations [53], having an impact in the sensorial characteristics of the final products [54]. _Streptococcus salivarius spp. thermophilus_ is an industrial strain used in starter cultures which participate in the formation of aroma (aroma compounds such as leucine, phenylalanine, and methionine-derived aroma compounds), flavor, and texture through the metabolic pathway of proteolysis, the biosynthesis of vitamins (B-group), as well as the production of extracellular polysaccharides [55]. Since the cheese sampling of the present study was performed in registered dairy establishments in which the production process is according to the EU legislation and the milk was pasteurized, it is possible that the detected _Streptococcus thermophilus_ strains originated from starter cultures [56]. _Microococcus luteus_ (1 isolate) detected only in six months ripened cheese. Due to its antimicrobial compounds, was found antagonistic to a group of foodborne pathogens such as Listeria monocytogenes and Salmonella spp. It is part of the microflora of the surface of smear-ripened cheees and can be found in the core part of the cheese [57]. Despite the presence of the beneficial microbiota in the core Feta cheese samples, which characterize their identity of the product and its quality properties, a small number of microbial isolates detected refer to possible spoilage commensals considered as markers of poor hygienic situations in the holistic process of Feta cheese production. _Bacillus cereus_, (one isolate) was detected in one of the six months ripening samples (Table 3). These bacteria are rare and sporulate to survive pasteurization temperatures. Their presence indicates poor sanitation [58]. _Candida lustantiae_ (2 isolates) and _Kluyveromyces lactis_ (3 isolates) are opportunistic yeasts, considered as spoilage but mozzarella cheese, where _Candida lustantiae_ is part of the natural microbiota counting 4-6 log cfu/g [59; 60]. _Corynebacterium species_ (two isolates) are aerobic microorganisms usually growing on the surface of the cheese [61] and hence the presence of _C. flavescens_ in the core of a cheese sample is probably due to cracks and breaches. The microbiota of Feta cheese, include diverse genera and reflect similarities and differences among the two ripening periods (three vs. six months).