Bacteriophage-host interactions in Streptococcus thermophilus and their impact on co-evolutionary processes.

Bacteriophages (or phages) represent a persistent threat to the success and reliability of food fermentation processes. Recent reports of phages that infect Streptococcus thermophilus have highlighted the diversification of phages of this species. Phages of S.

A structural discovery journey of streptococcal phages adhesion devices by AlphaFold2.

Successful bacteriophage infection starts with specific recognition and adhesion to the host cell surface. Adhesion devices of siphophages infecting Gram-positive bacteria are very diverse and remain, for the majority, poorly understood. These assemblies often comprise long, flexible, and multi-domain proteins, which limits their structural analyses by experimental approaches such as X-ray crystallography and electron microscopy.

Needle in a Whey-Stack: PhRACS as a Discovery Tool for Unknown Phage-Host Combinations.

The field of metagenomics has rapidly expanded to become the go-to method for complex microbial community analyses. However, there is currently no straightforward route from metagenomics to traditional culture-based methods of strain isolation, particularly in (bacterio)phage biology, leading to an investigative bottleneck. Here, we describe a method that exploits specific phage receptor binding protein (RBP)-host cell surface receptor interaction enabling isolation of phage-host combinations from an environmental sample.

Brussowvirus SW13 Requires a Cell Surface-Associated Polysaccharide To Recognize Its Streptococcus thermophilus Host.

Four acteriophage-nsensitive utants (BIMs) of the dairy starter bacterium Streptococcus thermophilus UCCSt50 were isolated following challenge with Brussowvirus SW13. The BIMs displayed an altered sedimentation phenotype. Whole-genome sequencing and comparative genomic analysis of the BIMs uncovered mutations within a family 2 glycosyltransferase-encoding gene (06955) located within the variable region of the cell wall-associated hamnose-lucose olymer (Rgp) biosynthesis locus (designated the gene cluster here).

Cell wall polysaccharides of Gram positive ovococcoid bacteria and their role as bacteriophage receptors.

Gram-positive bacterial cell walls are characterised by the presence of a thick peptidoglycan layer which provides protection from extracellular stresses, maintains cell integrity and determines cell morphology, while it also serves as a foundation to anchor a number of crucial polymeric structures. For ovococcal species, including streptococci, enterococci and lactococci, such structures are represented by rhamnose-containing cell wall polysaccharides, which at least in some instances appear to serve as a functional replacement for wall teichoic acids. The biochemical composition of several streptococcal, lactococcal and enterococcal rhamnose-containing cell wall polysaccharides have been elucidated, while associated functional genomic analyses have facilitated the proposition of models for individual biosynthetic pathways.

Revisiting the host adhesion determinants of Streptococcus thermophilus siphophages.

Available 3D structures of bacteriophage modules combined with predictive bioinformatic algorithms enabled the identification of adhesion modules in 57 siphophages infecting Streptococcus thermophilus (St). We identified several carbohydrate-binding modules (CBMs) in so-called evolved distal tail (Dit) and tail-associated lysozyme (Tal) proteins of St phage baseplates. We examined the open reading frame (ORF) downstream of the Tal-encoding ORF and uncovered the presence of a putative p2-like receptor-binding protein (RBP).

A cell wall-associated polysaccharide is required for bacteriophage adsorption to the Streptococcus thermophilus cell surface.

Streptococcus thermophilus strain ST64987 was exposed to a member of a recently discovered group of S. thermophilus phages (the 987 phage group), generating phage-insensitive mutants, which were then characterized phenotypically and genomically. Decreased phage adsorption was observed in selected bacteriophage-insensitive mutants, and was partnered with a sedimenting phenotype and increased cell chain length or aggregation.

Biodiversity of Phages in Global Dairy Fermentations.

strains are among the most widely employed starter cultures in dairy fermentations, second only to those of . The extensive application of this species provides considerable opportunity for the proliferation of its infecting (bacterio)phages. Until recently, dairy streptococcal phages were classified into two groups ( and groups), while more recently, two additional groups have been identified (5093 and 987 groups).

A Decade of Streptococcus thermophilus Phage Evolution in an Irish Dairy Plant.

Phages of present a major threat to the production of many fermented dairy products. To date, only a few studies have assessed the biodiversity of phages in dairy fermentations. In order to develop strategies to limit phage predation in this important industrial environment, it is imperative that such studies are undertaken and that phage-host interactions of this species are better defined.