Elucidation of the initial bacterial community of Ezine PDO cheese using next-generation sequencing

Abstract

This study aims to reveal initial bacterial consortia of Ezine PDO cheeses comprehensively by following a metagenomic approach. A total of 8 artisanal Ezine cheese samples were collected from the Bayramiç and Ezine districts of Çanakkale province of Turkey. Ezine cheese was found to contain Firmicutes, Bacteroidetes, and Proteobacteria phyla dominantly. Streptococcus, Lactococcus, and Lactobacillus genera dominated the microbiota with relative abundances of 4.47-56.07%, 7.33-20.34%, and 1.21-25.12%, respectively, followed by Bacteroides and Prevotella genera. Excluding two cheese samples obtained from the Ezine district, the most dominant species was Streptococcus thermophilus (8.24-54.34%). It was also found in greater proportions in the cheeses of the Bayramiç district. Unexpectedly, Lactobacillus graminis (11.50-23.63%) was the most abundant species in two samples collected from the Ezine district. However, lower bacterial diversity was determined in the samples collected from the Bayramiç district. The lowest species richness was 129 OTU-species in the cheeses from the Bayramiç district while the highest species richness was 267 OTU-species in cheeses from the Ezine district. In addition, the Simpson index was the highest in cheeses from the Ezine district, where different species were evenly distributed. Permutational multivariate analysis of variance tests also confirmed that the differences in the structure of bacterial consortia in cheeses from two different districts were statistically significant. This study will provide pioneer data for further investigations on the role of complex bacterial composition in maintaining and improving the quality and safety of Ezine cheese.

Keywords: Cheese microbiota; Diversity indexes; Species richness; Streptococcus thermophilus; White brined cheese.