Purpose: A comprehensive investigation of the Feta cheese microbial ecosystem using metagenomics analysis.
Methods: In the present study, 12 artisanal Feta cheese samples from geographically dispersed regions in Greece along with five industrially produced Feta cheese samples were considered. After sensorial evaluation, 4 artisanal and 2 industrial samples were selected for further analysis. Samples were subjected to classical microbiological analysis, using selective growth media. Moreover, after total DNA extraction performed using a novel protocol developed in our laboratory, metagenomics analysis was performed by employing the 16S (bacteria) and ITS (yeasts) diversity assays. The data of the metagenomics analysis were analyzed using the MG-RAST server.
Results: The results of the classical microbiological analysis showed the presence of both bacteria and yeasts in all Feta cheeses, with bacteria being the dominant microbial community. Metagenomics analysis revealed the high variation among the numbers of bacterial and yeast species present in the ecosystem of the Feta cheese samples, with the number of the yeast species being almost twofold compared to the respective number of bacteria. Concerning bacteria, the dominant species were Streptococcus thermophilus and Lactobacillus delbrueckii (industrial samples) and Lactococcus lactis (artisanal samples). Furthermore, in all cheese samples, 4 yeast species were found to be the most abundant, namely Kluyveromyces lactis, Debaromyces hansenii, Pichia membranifaciens and Cryptococcus cyanovorans.
Significance: This study is the first report on the metagenomics analysis of the microbial diversity of Feta cheese.