Biodiversity of Phages Infecting the Dairy Bacterium Streptococcus thermophilus.
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ABSTRACT:
SUBMITTER: Hanemaaijer L
PROVIDER: S-EPMC8470116 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Streptococcus thermophilus strains are among the most widely employed starter cultures in dairy fermentations, second only to those of Lactococcus lactis. 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 (cos and pac groups), while more recently, two additional groups have been identified (5093 and 987 groups). This highlights the requirement for consistent monitoring of phage populations in the industry. Here, we report a survey of 35 samples of whey derived from 27 dairy fermentation facilities in ten countries against a panel of S. thermophilus strains. This culminated in the identification of 172 plaque isolates, which were characterized by multiplex PCR, restriction fragment length polymorphism analysis, and host range profiling. Based on this characterisation, 39 distinct isolates representing all four phage groups were selected for genome sequencing. Genetic diversity was observed among the cos isolates and correlations between receptor binding protein phylogeny and host range were also clear within this phage group. The 987 phages isolated within this study shared high levels of sequence similarity, yet displayed reduced levels of similarity to those identified in previous studies, indicating that they are subject to ongoing genetic diversification.
| S-EPMC6213268 | biostudies-literature
Project description:Streptococcus thermophilus is a lactic acid bacterium commonly used for the manufacture of yogurt and specialty cheeses. Virulent phages represent a major risk for milk fermentation processes worldwide, as they can inactivate the added starter bacterial cells, leading to low-quality fermented dairy products. To date, four genetically distinct groups of phages infecting S. thermophilus have been described. Here, we describe a fifth group. Phages P738 and D4446 are virulent siphophages that infect a few industrial strains of S. thermophilus The genomes of phages P738 and D4446 were sequenced and found to contain 34,037 and 33,656 bp as well as 48 and 46 open reading frames, respectively. Comparative genomic analyses revealed that the two phages are closely related to each other but display very limited similarities to other S. thermophilus phages. In fact, these two novel S. thermophilus phages share similarities with streptococcal phages of nondairy origin, suggesting that they emerged recently in the dairy environment.IMPORTANCE Despite decades of research and adapted antiphage strategies such as CRISPR-Cas systems, virulent phages are still a persistent risk for the milk fermentation industry worldwide, as they can cause manufacturing failures and alter product quality. Phages P738 and D4446 are novel virulent phages that infect the food-grade Gram-positive bacterial species Streptococcus thermophilus These two related viruses represent a fifth group of S. thermophilus phages, as they are significantly distinct from other known S. thermophilus phages. Both phages share similarities with phages infecting nondairy streptococci, suggesting their recent emergence and probable coexistence in dairy environments. These findings highlight the necessity of phage surveillance programs as the phage population evolves in response to the application of antiphage strategies.
| S-EPMC7301855 | biostudies-literature
Project description:The lactic acid bacterium Streptococcus thermophilus is widely used for the manufacture of yogurt and cheese. This dairy species of major economic importance is phylogenetically close to pathogenic streptococci, raising the possibility that it has a potential for virulence. Here we report the genome sequences of two yogurt strains of S. thermophilus. We found a striking level of gene decay (10% pseudogenes) in both microorganisms. Many genes involved in carbon utilization are nonfunctional, in line with the paucity of carbon sources in milk. Notably, most streptococcal virulence-related genes that are not involved in basic cellular processes are either inactivated or absent in the dairy streptococcus. Adaptation to the constant milk environment appears to have resulted in the stabilization of the genome structure. We conclude that S. thermophilus has evolved mainly through loss-of-function events that remarkably mirror the environment of the dairy niche resulting in a severely diminished pathogenic potential.
| S-EPMC7416660 | biostudies-literature
Project description:Despite the persistent and costly problem caused by (bacterio)phage predation of Streptococcus thermophilus in dairy plants, DNA sequence information relating to these phages remains limited. Genome sequencing is necessary to better understand the diversity and proliferative strategies of virulent phages. In this report, whole genome sequences of 40 distinct bacteriophages infecting S. thermophilus were analyzed for general characteristics, genomic structure and novel features. The bacteriophage genomes display a high degree of conservation within defined groupings, particularly across the structural modules. Supporting this observation, four novel members of a recently discovered third group of S. thermophilus phages (termed the 5093 group) were found to be conserved relative to both phage 5093 and to each other. Replication modules of S. thermophilus phages generally fall within two main groups, while such phage genomes typically encode one putative transcriptional regulator. Such features are indicative of widespread functional synteny across genetically distinct phage groups. Phage genomes also display nucleotide divergence between groups, and between individual phages of the same group (within replication modules and at the 3' end of the lysis module)-through various insertions and/or deletions. A previously described multiplex PCR phage detection system was updated to reflect current knowledge on S. thermophilus phages. Furthermore, the structural protein complement as well as the antireceptor (responsible for the initial attachment of the phage to the host cell) of a representative of the 5093 group was defined. Our data more than triples the currently available genomic information on S. thermophilus phages, being of significant value to the dairy industry, where genetic knowledge of lytic phages is crucial for phage detection and monitoring purposes. In particular, the updated PCR detection methodology for S. thermophilus phages is highly useful in monitoring particular phage group(s) present in a given whey sample. Studies of this nature therefore not only provide information on the prevalence and associated threat of known S. thermophilus phages, but may also uncover newly emerging and genomically distinct phages infecting this dairy starter bacterium.
| S-EPMC5601072 | biostudies-literature
Project description:Receptors on the cell surfaces of bacterial hosts are essential during the infection cycle of bacteriophages. To date, the phage receptors of the industrial relevant dairy starter bacterium Streptococcus thermophilus remain elusive. Thus, we set out to identify cell surface structures that are involved in host recognition by dairy streptococcal phages. Five industrial S. thermophilus strains sensitive to different phages (pac type, cos type, and the new type 987), were selected to generate spontaneous bacteriophage-insensitive mutants (BIMs). Of these, approximately 50% were deselected as clustered regularly interspaced short palindromic repeat (CRISPR) mutants, while the other pool was further characterized to identify receptor mutants. On the basis of genome sequencing data, phage resistance in putative receptor mutants was attributed to nucleotide changes in genes encoding glycan biosynthetic pathways. Superresolution structured illumination microscopy was used to visualize the interactions between S. thermophilus and its phages. The phages were either regularly distributed along the cells or located at division sites of the cells. The cell wall structures mediating the latter type of phage adherence were further analyzed via phenotypic and biochemical assays. Altogether, our data suggested that phage adsorption to S. thermophilus is mediated by glycans associated with the bacterial cell surface. Specifically, the pac-type phage CHPC951 adsorbed to polysaccharides anchored to peptidoglycan, while the 987-type phage CHPC926 recognized exocellular polysaccharides associated with the cell surface.IMPORTANCE Streptococcus thermophilus is widely used in starter cultures for cheese and yoghurt production. During dairy fermentations, infections of bacteria with bacteriophages result in acidification failures and a lower quality of the final products. An understanding of the molecular factors involved in phage-host interactions, in particular, the phage receptors in dairy bacteria, is a crucial step for developing better strategies to prevent phage infections in dairy plants.
| S-EPMC6238053 | biostudies-literature
Project description:Streptococcus thermophilus ASCC 1275 (ST 1275), a typical dairy starter bacterium, yields the highest known amount (~1,000 mg/L) of exopolysaccharide (EPS) in milk among the species of S. thermophilus. The addition of this starter in milk fermentation exhibited texture modifying properties for fermented dairy foods such as yogurt and cheese in the presence of EPS as its important metabolite. In this genomic study, a novel eps gene cluster for EPS assembly of repeating unit has been reported. It contains two-pair epsC-epsD genes which are assigned to determine the chain length of EPS. This also suggests this organism produces two types of EPSs - capsular and ropy EPS, as observed in our previous studies. Additionally, ST 1275 appears to exhibit effective proteolysis system and sophisticated stress response systems to stressful conditions, and has the highest number of four separate CRISPR/Cas loci. These features may be conducive to milk adaptation of this starter and against undesirable bacteriophage infections which leads to failure of milk fermentation. Insights into the genome of ST 1275 suggest that this strain may be a model high EPS-producing dairy starter.
| S-EPMC4021336 | biostudies-literature
Project description:UnlabelledWe present the complete genome sequences of four members of a novel group of phages infecting Streptococcus thermophilus, designated here as the 987 group. Members of this phage group appear to have resulted from genetic exchange events, as evidenced by their "hybrid" genomic architecture, exhibiting DNA sequence relatedness to the morphogenesis modules of certain P335 group Lactococcus lactis phages and to the replication modules of S. thermophilus phages. All four identified members of the 987 phage group were shown to elicit adsorption affinity to both their cognate S. thermophilus hosts and a particular L. lactis starter strain. The receptor binding protein of one of these phages (as a representative of this novel group) was defined using an adsorption inhibition assay. The emergence of a novel phage group infecting S. thermophilus highlights the continuous need for phage monitoring and development of new phage control measures.ImportancePhage predation of S. thermophilus is an important issue for the dairy industry, where viral contamination can lead to fermentation inefficiency or complete fermentation failure. Genome information and phage-host interaction studies of S. thermophilus phages, particularly those emerging in the marketplace, are an important part of limiting the detrimental impact of these viruses in the dairy environment.
| S-EPMC4988201 | biostudies-literature
Project description:Lactobacillus brevis is a lactic acid bacterium that is known as a food and beverage spoilage organism, and more specifically as a beer-spoiler. Phages of L. brevis have been described, but very limited data is available regarding temperate phages of L. brevis. Temperate phages may exert benefits to the host, while they may also be employed to combat beer spoilage. The current study reports on the incidence of prophage sequences present in nineteen distinct L. brevis genomes. Prophage induction was evaluated using mitomycin C exposure followed by genome targeted-PCR, electron microscopy and structural proteome analysis. The morphological and genome sequence analyses revealed significant diversity among L. brevis prophages, which appear to be dominated by members of the Myoviridae phage family. Based on this analysis, we propose a classification of L. brevis phages into five groups.
| S-EPMC6805780 | biostudies-literature
Project description:Lipoprotein Ltp encoded by temperate Streptococcus thermophilus phage TP-J34 is the prototype of the wide-spread family of host cell surface-exposed lipoproteins involved in superinfection exclusion (sie). When screening for other S. thermophilus phages expressing this type of lipoprotein, three temperate phages-TP-EW, TP-DSM20617, and TP-778-were isolated. In this communication we present the total nucleotide sequences of TP-J34 and TP-778L. For TP-EW, a phage almost identical to TP-J34, besides the ltp gene only the two regions of deviation from TP-J34 DNA were analyzed: the gene encoding the tail protein causing an assembly defect in TP-J34 and the gene encoding the lysin, which in TP-EW contains an intron. For TP-DSM20617 only the sequence of the lysogeny module containing the ltp gene was determined. The region showed high homology to the same region of TP-778. For TP-778 we could show that absence of the attR region resulted in aberrant excision of phage DNA. The amino acid sequence of mature LtpTP-EW was shown to be identical to that of mature LtpTP-J34, whereas the amino acid sequence of mature LtpTP-778 was shown to differ from mature LtpTP-J34 in eight amino acid positions. LtpTP-DSM20617 was shown to differ from LtpTP-778 in just one amino acid position. In contrast to LtpTP-J34, LtpTP-778 did not affect infection of lactococcal phage P008 instead increased activity against phage P001 was noticed.
| S-EPMC3952083 | biostudies-literature
Project description:We report here the complete genome sequence of Streptococcus thermophilus DGCC 7710. S. thermophilus is widely used in industrial dairy production.
| S-EPMC5805889 | biostudies-literature