Dairy streptococcal cell wall and exopolysaccharide genome diversity.

The large-scale and high-intensity application of species in milk fermentation processes is associated with a persistent threat of (bacterio)phage infection. Phage infection of starter cultures may cause inconsistent, slow or even failed fermentations with consequent diminished product quality and/or output. The phage life cycle commences with the recognition of, and binding to, a specific host-encoded and surface-exposed receptor, which in the case of can be the rhamnose-glucose polysaccharide (RGP; specified by the gene cluster) or exopolysaccharide (EPS; specified by the gene cluster). The genomic diversity of 23 . strains isolated from unpasteurized dairy products was evaluated, including a detailed analysis of the and loci. In the present study, five novel genotypes were identified while variations of currently recognized gene cluster types were also observed. Furthermore, the diversity of genotypes amongst retrieved isolates positively correlated with phage diversity based on phageome analysis of eight representative dairy products. Our findings therefore substantially expand our knowledge on strain and phage diversity in (artisanal) dairy products and highlight the merit of phageome analysis of artisanal and traditional fermented foods as a sensitive marker of dominant microbiota involved in the fermentation.