Microbial diversity of Pélardon, an artisanal raw goat milk cheese

Artisanal fermented foods represent a cultural heritage that needs to be preserved and protected; this is particularly true in the context of industrial food standardization. The manufacture and unique sensorial properties of such products mainly relies on autochthonous complex microbiota and their activities. The present study focuses on Pelardon, a Protection Designation of Origin (PDO) French artisanal soft rind cheese, exclusively produced from raw goat’s milk using a back slopping method in mountainous areas in southern France. Pelardon microbial ecology and dynamics were studied by culture-dependent and -independent methods. A complete production was followed at an artisanal cheese-making factory and sampling was performed at different cheese-making steps from the raw milk to cheese ripened for 3 months. Different population were monitored on different media. Fungal and bacterial isolates were collected and identified. The achieved results were compared to metabarcoding analyses targeting ITS 2 region for Fungi and V3-V4 region of the 16S RNAr for Bacteria. Focusing on cultivable microorganisms, higher microbial populations were observed in whey used for inoculation compared to raw milk. Results also highlighted the importance of fungi. Despite the initial low inoculum, yeast growth began as early as milk acidification and during the renetting step. Metagenetic results outlined the differences in both fungal and bacterial communities between cheese rind and core samples. Bacterial diversity increased during the ripening specially in the rind compared to the curd stage. Although yeasts were present early in the processing, fungal diversity remained limited at the end of ripening. To better understand the origin of the observed microbial diversity, environmental and raw material samples were also investigated and ongoing work should provide new insights about the dynamics of these microbial communities.