Influence of the Mefite D'Ansanto Valley on the chemical characteristics and microbial consortia of raw sheep milk for the production of Pecorino Carmasciano cheese

Pecorino Carmasciano cheese is produced from the milk of sheep that graze in a unique environment called Mefite d'Ansanto, a non-volcanic site located in the Ansanto Valley, in the province of Avellino (Campania, Italy). In order to provide new insights into the determinants of the distinctive quality of ewe milk used for the production of Pecorino Carmasciano cheese, we examined the chemical characteristics of the milk and evaluated the correlation with the bacterial composition, analysed using a high-throughput sequencing approach. The milk was analysed and compared with that belonging to sheep from other provinces of the Campania region (Caserta and Salerno). Milk from sheep grazing in the Ansanto Valley (Avellino province) especially showed significantly higher concentrations of proteins, iron, potassium and zinc compared to the other sheep milk studied (from Caserta and Salerno provinces). The pipelines used for metagenomic classification highlighted the predominant phyla in milk from the different provinces, with Proteobacteria as the dominant phylum, followed by Firmicutes and Bacteroides. Metagenomic analysis revealed however a greater diversity of families, genera and species in the milk from Avellino than in those from Caserta and Salerno. The statistical analysis of the data acquired on raw milk samples (physico-chemical, microbiological and amino acid composition) showed that the presence of metals had an impact on the higher number of species detected in milk from Avellino. Moreover, peculiar bacterial species (Anoxybacillus kestanbolensis, Petrobacter succinatimandens and Thermoanaerobacterium saccharolyticum), appeared related to the specific area of the Mefite.