Microbial Ecology of Artisanal Feta and Kefalograviera Cheeses, Part I: Bacterial Community and Its Functional Characteristics with Focus on Lactic Acid Bacteria as Determined by Culture-Dependent Methods and Phenotype Microarrays

Abstract

Artisanal cheesemaking is still performed using practices and conditions derived from tradition. Feta and Kefalograviera cheeses are very popular in Greece and have met worldwide commercial success. However, there is a lack of knowledge regarding their lactic acid microecosystem composition and species dynamics during ripening. Thus, the aim of the present study was to assess the microecosystem as well as the autochthonous lactic acid microbiota during the ripening of artisanal Feta and Kefalograviera cheeses. For that purpose, raw sheep’s milk intended for cheesemaking, as well as Feta and Kefalograviera cheeses during early and late ripening were analyzed, and the lactic acid microbiota was identified using the classical phenotypic approach, clustering with PCR-RAPD and identification with sequencing of the 16S-rRNA gene, as well as with the Biolog GEN III microplates. In addition, the functional properties of the bacterial community were evaluated using the Biolog EcoPlates, which consists of 31 different carbon sources. In general, concordance between the techniques used was achieved. The most frequently isolated species from raw sheep’s milk were Enteroroccus faecium, Lactiplantibacillus plantarum and Pediococcus pentosaceus. The microecosystem of Feta cheese in the early ripening stage was dominated by Lp. plantarum and E. faecium, whereas, in late ripening, the microecosystem was dominated by Weissella paramesenteroides. The microecosystem of Kefalograviera cheese in the early ripening stage was dominated by Levilactobacillus brevis and E. faecium, and in late ripening by W. paramesenteroides and E. faecium. Finally, Carbohydrates was the main carbon source category that metabolized by all microbial communities, but the extent of their utilization was varied. Kefalograviera samples, especially at early ripening, demonstrated higher metabolic activity compared to Feta cheese. However, dominating species within microbial communities of the cheese samples were not significantly different.

Microbial Ecology of Sheep Milk, Artisanal Feta, and Kefalograviera Cheeses. Part II: Technological, Safety, and Probiotic Attributes of Lactic Acid Bacteria Isolates

“…In the present study, weak caseinolytic strains were detected in all species assessed. Interestingly, the majority of them were isolated from the same source, namely Feta cheese in early ripening stage [20]. Caseinolysis does not seem to be a property shared among the majority of dairy LAB; in addition, the extend of proteolytic activity is strain-dependent [30,32,34,[37][38][39][44][45][46][47][48].…”

“…A total of 189 lactic acid bacteria (LAB) strains of the collection of Dairy Research Department (DRD) of Hellenic Agricultural Organization "DIMITRA" (ELGO-DIMITRA), isolated from sheep milk and artisanal Feta and Kefalograviera cheeses [20], belonging to the species Enterococcus faecium (46 strains), E. faecalis (3 strains), Lactococcus lactis (7 strains), Pediococcus pentosaceus (29 strains), Leuconostoc mesenteroides (6 strains), Lactiplantibacillus pentosus (2 strains), Latilactobacillus curvatus (6 strains), Lp. plantarum (29 strains), Levilac-tobacillus brevis (29 strains), and Weissella paramesenteroides (32 strains) were included in the present study (Table S1).…”

“…Milk acidification and coagulation was examined in 74 LAB representative strains, which were selected based on their different isolation source or separate genotypic cluster [20] DRD 2616DRD , 2634DRD , 2635DRD , 2652DRD , 2655DRD , 2657DRD , 2676DRD , 2681DRD , 2689DRD , 2694DRD , 2748DRD , 2749DRD , 2752DRD , 2753DRD , 2761. Overnight bacterial cultures of the representative strains were used to inoculate (1% inoculum) 10 mL skim milk (LAB M).…”

Impact of an Omega-3-Enriched Sheep Diet on the Microbiota and Chemical Composition of Kefalograviera Cheese

“…Microbiota is a key factor responsible for all sensory characteristics and product quality and may be beneficial in the case of probiotic microorganisms or harmful in the case of spoilage and pathogenic microorganisms [ 20 , 21 , 38 ]. Although we searched thoroughly for research papers on the effect of increased dietary omega-3 fatty acids on the microbiota of Kefalograviera cheese, we could not locate any.…”

“…Going one step further, a pivotal role in cheese qualitative characteristics is also played by the cheese-associated microbiota by metabolizing carbohydrates and proteins during the ripening procedures [ 19 ]. Cheese microbiota can be influenced by the physicochemical milk’s compounds and linked to several sheep feeding-related and geographical location factors [ 20 , 21 ]. Lactic acid bacteria in non-starter cultures have the ability to increase the bioactive fatty acids content in sheep cheeses.…”