Résumé
Background and Aims: Microorganisms are essential in cheese-making and ripening processes (starter, development of the organoleptic properties). The composition and structure of the raw milk cheese bacterial ecosystem depend in particular on the production practices (from milking to ripening). This study aims to characterise the bacterial microbiota of a French artisanal raw milk Uncooked Pressed Cheese (UPC) throughout the cheese-making and ripening processes with a special focus on the bacterial communities present on contact surfaces during the cheese manufacturing.Methods: Twenty farms situated in French mountains, producing an artisanal Protected Designation of Origin (PDO) bovine raw milk UPC were visited during summer 2023 (when the cows were in the mountain pastures). A comprehensive collection of samples corresponding to 16 distinct points (raw milk, cheese, contact surfaces, etc.) were collected during milking and cheese-making processes. Bacterial communities were analysed using 16S rRNA gene metabarcoding and alpha diversity was estimated by calculating Shannon index.Results: The study revealed high bacterial diversity in raw milk, milk filters, and contact surfaces.Conversely, samples involving starter cultures exhibited reduced diversity. Most of the sequences were associated with starter Lactic Acid Bacteria (Streptococcus, Lactobacillus, Lactococcus, etc.) or ripening-related taxa like orynebacterium, Intestinibacter, Acinetobacter, etc. Conclusions: This study advances our knowledge of intricate microbial dynamics in cheese production. Further analyses should be done to elucidate the precise role of contact surfaces microbiota in the cheese production process.