Microbial Ecology of Pecorino Siciliano PDO Cheese Production Systems

Pecorino Siciliano PDO is a semi-hard cheese that is produced in wooden vats using raw sheep's milk and its associated autochthonous microbial community. In the present study, we evaluated the microbial ecology of the milk, curd and whey from five Pecorino Siciliano PDO-producing farms in Sicily using a combination of metagenomic and microbiological approaches. We present an overview of the species and strain-level diversity of dairy lactococcal and streptococcal isolates using established genotyping tools and compare the lactic acid bacterial populations present in samples from these farms. Whole genome sequences of representative isolates of Lactococcus spp. and Streptococcus thermophilus were elucidated and the genetic diversity of the strains was established through analysis of predicted phage-resistance systems and prophage-associated regions. The analysis revealed farm-specific dairy lactococcal and streptococcal isolates that possess diverse genotypic features including newly described phage-resistance systems.