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Staphylococcus aureus is a representative pathogenic bacterium carefully controlled in the dairy industry because it causes bovine mastitis and thus, can enter the dairy chain. Furthermore, the emergence of multi-drug resistant S. aureus is a big problem. We previously isolated a Lactococcus lactis strain producing a bacteriocin that exhibited strong antimicrobial activity against S. aureus. In this study, we investigated the synergistic inhibition of S. aureus by the bacteriocin and a bacteriophage (SAP84) which is specific to the organism. The bacteriocin (12.5–100 AU/mL) inhibited the growth of S. aureus KCTC 3881 in a dose-dependent manner, as did the bacteriophage SAP84 (0.001–1 MOI; multiplicity of infection). Co-treatment with the bacteriocin (100 AU/mL) and the bacteriophage (0.1 MOI) significantly inhibited the growth of S. aureus compared to each treatment alone (bacteriocin or bacteriophage), indicating the two components showed synergistic inhibition of S. aureus. Therefore, the bacteriocin and bacteriophage combination can be used as a good strategy for controlling pathogenic bacteria.

To reduce staphylococcal food poisoning (SFP), a phage-encoded cell wall hydrolase called endolysin has emerged as an attractive antibacterial agent. In this study, the Staphylococcus aureus infecting phage vB_SauS-SAP27 (ϕSAP27) was isolated from sewage and characterized morphologically and genetically. ϕSAP27 was identified as Siphoviridae temperate phage, with a genome of 43 kbp. A ϕSAP27 endolysin named LysSAP27 was produced recombinantly in Escherichia coli. LysSAP27 exhibited the highest activity at neutral pH and a temperature of 30 °C, and its lytic activity was upregulated by calcium ions. Following optimization of the enzymatic conditions, LysSAP27 was applied to S. aureus-contaminated milk. Treatment with 2 μM LysSAP27 led to a significant bactericidal effect, corresponding to a reduction in bacterial titer by 2.8 log CFU/mL within 1 h and 3.4 log CFU/mL within 2 h. Therefore, LysSAP27 could be used as an effective antimicrobial agent to prevent SFP in food. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10068-021-00910-2.

Foodborne Shiga toxin-producing Escherichia coli (STEC) cause severe diarrhea and hemolytic uremic syndrome (HUS) in humans. However, traditional methods for STEC sterilization are difficult to apply to fresh food. To control the pathogen, phage infecting E. coli O157:H7 were isolated and characterized. The isolated phage vB_EcoM-ECP26 had an icosahedral head and a contractile tail, and was classified as belonging to the Myoviridae family. The phage showed a broad host range against STEC and exhibited a large burst size of 1914 PFU/cell. The phage was highly stable at high temperatures (65 °C) and wide ranges of pH (4–10). The genome of vB_EcoM-ECP26 consists of 136,993 nucleotides, 214 open reading frames, and does not contain lysogenicity-related genes. Phylogenetic analysis showed that vB_EcoM-ECP26 is a V5-like species. STEC O157 growth was inhibited by vB_EcoM-ECP26 for 8 h. Furthermore, this phage not only significantly decreased the STEC population (p

Virulent Cronobacter sakazakii bacteriophage ES2 was isolated from swine fecal samples, and the genome sequence by was determined GS-Flx. Bacteriophage ES2 had a double-stranded DNA genome with a length of 22,162 bp and a G+C content of 50.08%. The morphological characteristics under a transmission electron microscope indicated that bacteriophage ES2 belongs to the family Myoviridae. The structural proteins, including the phage coat protein, were separated by SDS-PAGE and identified by Q-TOF. Bioinformatics analysis of the bacteriophage genome revealed 30 putative open reading frames (ORFs). The predicted protein products of the ORFs were determined and described. To our knowledge, the genome of the newly isolated bacteriophage ES2 was not significantly similar to that of any previously reported bacteriophages of members of the family Enterobacteriaceae.

Bacteriophages have been intensively-studied and applied in a variety of practical applications such as biocontrol of food-borne pathogens. Especially, endolysin of bacteriophage is highly specific to host strains that can hydrolyze cell wall. To get the control agent for foodpoisoning Bacillus cereus, cloning and nucleotide sequence of putative endolysin from temperate phage 250 (Tp250) of emetic B. cereus 250 were investigated. Tp250 was induced by mitomycin C and belonged to Siphoviridae family. Tp250, a circular dsDNA genome of 56,505 bp, consisted of various structural and functional genes for survival or propagation. ORFs from Tp250 were involved in replication, head morphogenesis, head-to-tail joining, tail morphogenesis, lysogenic module, host lysis, and other functional genes such as related metabolisms. For cloning of putative endolysin, Tp 250 DNA was extracted and pLYS250 was constructed. The pLYS250 had 752 ORF encoding a putative endolysin with 250 amino acids, which was expressed by around 28 kDa in Escherichia coli. Therefore, Tp250 and the endolysin might be applied as one of agents to reduce B.cereus pathogen in foods directly or through over-expression and purification.

The bacteriophage ES2 is a virus for bacterial host cells. Unlike other phages that are known for their therapeutic effects, the ES2 phage has never been clearly examined as a therapeutic agent. To systematically and conclusively evaluate its therapeutic efficacy, the expression of the surface markers CD86, CD40, and MHCII, the production of the proinflammatory cytokines IL-6, IL-1α, IL-1β, and TNF-α, and the underlying NF-κB signaling pathway in murine bone marrow-derived dendritic cells (BM-DCs) in response to ES2 phage infection were examined. The bacteriophage ES2, which was isolated from swine fecal samples an antigen, affected the expression of the cell surface molecules and proinflammatory cytokines that are associated with the DC maturation processes. Treatment with ES2 phage also led to NF-κBp65 activation and translocation to the nucleus, which indicates the activation of NF-κB signaling. Furthermore, the ES2 phage induced the promoter activity of IL-12p40. Our chromatin immunoprecipitation assay revealed that p65 was enriched at the IL12-p40 promoter as a direct target of chromatin. The present study demonstrates that the ES2 phage potently induces DC maturation via immune-enhancement processes.

Bacteriophage TEM126, a newly isolated temperate phage from a mitomycin-C-induced lysate of wild-type Staphylococcus aureus isolated from food, has an isometric head, a noncontractile tail, and a double-stranded DNA genome with a length of 33,540 bp and a G+C content of 33.94%. Bioinformatics analysis of the phage genome revealed 44 putative open reading frames (ORFs). Predicted protein products of the ORFs were determined and described. Temperate phage TEM126 can be classified as a member of the family Siphoviridae by morphology and genome structure. Temperate phage TEM126 showed 84% similarity with Staphylococcus phage phiNM1. To our knowledge, this is the first report of genomic sequencing and characterization of temperate phage TEM126 from a wild-type S. aureus isolated from foods in Korea.

Enterococcus faecalis is an important bacterium for use as a probiotic and is an opportunistic pathogen in human beings. The antibiotic resistance acquired by E. faecalis is restricted to antibiotics used in the clinical setting. While screening for alternative antibiotics for use against multidrug-resistant E. faecalis , we isolated a virulent enterococcal bacteriophage, SAP6, belonging to the family Siphoviridae . To our knowledge, this study is the first to report the complete genome sequence of bacteriophage SAP6, which might be used as a therapeutic agent in combination with alternative antibiotics for multidrug-resistant E. faecalis .