Identification of Bacterial Biodiversity and Volatile Fraction of Bitto Storico Cheese in Different Alpine Pasture Areas

Bitto Storico cheese is a raw milk seasonal cheese produced in the Orobic Alps, whose production is closely associated to local traditional activities and alpine pastures. The aim of this work was to characterize the microbiota diversity and the volatile fractions of cheese produced in different alpine pasture areas. Fifty-four Bitto Storico cheeses samples, produced in six different Alpine pastures, were collected and processed. Bacterial DNA was extracted using an optimized protocol and 16S rRNA gene amplicons on V3-V4 region analyzed by Miseq (Illumina). The volatile fraction was characterized by means of Solid Phase Extraction-Gas Chromatography-Mass Spectrometry (SPME-GC-MS). The microbial community of ripened cheese was mainly dominated by Firmicutes phylum with a high abundance of Streptococcaceae and Lactobacillaceae. Each Alpine area was characterized by peculiar bacterial communities, due, probably, to the pasture composition and the cheesemaking process. A total of 24 volatile compounds resulting from microbial activity and diet were found, the formers being mostly alcohols and esters, the latter being terpenes derived directly from the pasture.