Isolation Of Bacteriophages Research Articles

102 Development of a Bacteriophage-Based Feed Additive to Prevent Bovine Liver Abscesses

Abstract In the US, beef cattle feedlots commonly use antibiotic feed additives, such as tylosin and virginiamycin, to prevent liver abscesses, which can cause significant economic losses and animal welfare concerns. However, growing public and regulatory pressure to curb the proliferation of antibiotic resistant bacteria has prompted a need to reduce or eliminate their use. As an alternative, our group is working on a bacteriophage-based feed additive that targets Fusobacterium necrophorum, the primary cause of bovine liver abscesses, with the aim of reducing or eliminating the dependence on antibiotic feed additives. Using a combination of phage isolation techniques, we identified and characterized fifteen new F. necrophorum phages belonging to six genetically distinct groups. These phages exhibited a broad intraspecific host range and could infect various contemporary F. necrophorum strains isolated from different regions of the United States. All the phages were temperate, with dsDNA genomes ranging from around 36 kbp to 114 kbp. Almost all contemporary F. necrophorum isolates were found to have one or more active prophages upon bacterial genome sequencing and prophage induction. In vitro evolution resulted in the recovery of a potential virulent mutant, φBB37, which inhibited the growth of the high leukotoxin-producing F. necrophorum 8L1 strain for over 40 hours in vitro. Phage cocktails proved effective for up to 60 hours. After minimal optimization, most phages demonstrated high productivity (> 109 PFU/mL) and little yield variation during scale-up, highlighting their commercial potential. Unexpectedly, we discovered a previously unrecognized Fusobacterium species, Fusobacterium varium, is widely prevalent and frequently the most abundant member of the genus in cattle rumen. Previous studies on liver abscess control in cattle have almost exclusively focused on F. necrophorum, which may explain the lack of effectiveness observed. To elucidate the ecological role and potential pathogenicity of ruminal F. varium, we conducted genome sequencing and found these bovine strains to have multiple virulence factors and high similarity to human clinical isolates. However, phages with the ability to infect F. varium were plentiful in rumen fluid, with several demonstrating purely lytic activity. To assess the safety and in vivo dynamics of F. necrophorum and F. varium phage cocktails, a small-scale animal trial was recently conducted with ten cannulated cattle.

Isolation, characterization, and application of bacteriophage cocktails for the biocontrol of Pseudomonas fluorescens group strains in whole and skimmed milk.

Pseudomonas fluorescens group strains can lead to spoilage of milk as well as loss of quality in dairy products through their heat-resistant enzymes. Phages are important alternatives for combating spoilage bacteria in food industry and used successfully in many applications. The aim of this study was the isolation and characterization of phages and to assess the efficiency of a phage cocktail in whole and skimmed milk. For this purpose, phages effective against Pseudomonas fluorescens (L23.2), Pseudomonas tolaasii (P22.1), and Pseudomonas rhodesiae (A11.1) were isolated. Their host range was found to be highly specific, and the transmission electron micrographs indicates that they belonged to Tectiviridae family. Their genome sizes were found to be vary between 38.3 and 53.5 kb. The latent periods and burst sizes were determined as 15, 10, 15 min and 91, 20, 80 PFU/infected cell for L23.2, P22.1, and A11.1, respectively. All three phages were found to be sensitive to low pH and high temperature. The effect of the phage cocktail was monitored in milk with different fat contents during storage at 4 °C for 5 days. As a result, bacterial reductions up to 4.09 and 5.29 log-units were observed for the whole and skimmed milk, respectively. Thus, the efficacy of a phage cocktail against a bacterial mixture of different P. fluorescens strains was tested in milk samples with different fat contents in accordance with real-life scenarios for the first time.

Isolation, Characterization of Enterococcus phages and their application in control of E. faecalis in milk.

Isolation and characterization of Enterococcus phages and application of phage cocktail to control E. faecalis in milk. For phage isolations, double layer agar method was used. Host range of the phages were determined by the spot test. Twelve phages with varying host ranges were isolated. Phages PEF1, PEF7b, and PEF9 with different host ranges and lytic activities were selected for phage cocktails. Compared to two-phages cocktails tested, the cocktail containing all the three phages displayed stronger antibacterial and biofilm removal activities. The cocktail treatment reduced viable E. faecalis in biofilm by 6 log within 6h at both 30 and 4°C. In milk, the cocktail gradually reduced the viable count of E. faecalis and the count reached below the lower limit of detection at 48h at 4°C. The strong bactericidal and biofilm removal activities of the phage cocktail suggests the potential of this cocktail as a natural biocontrol agent for combating E. faecalis in milk. Enterococcus faecalis is an opportunistic pathogen being transmitted from food to humans and causes disease. This study demonstrated the effectiveness of the phage cocktail consisted of new isolated phages in controlling E. faecalis in food.

Isolation, Characterization and Genomic Analysis of a Novel Jumbo Phage, AerS_266, That Infects Aeromonas salmonicida.

Aeromonas salmonicida is the causative agent of septicemia in fish, and it is associated with significant economic losses in the aquaculture industry. While piscine Aeromonas infections are mainly treated with antibiotics, the emergence of resistance in bacterial populations requires the development of alternative methods of treatment. The use of phages can be one of them. A novel A. salmonicida jumbo phage, AerS_266, was isolated and characterized. This phage infects only mesophilic A. salmonicida strains and demonstrates a slow lytic life cycle. Its genome contains 243,674 bp and 253 putative genes: 84 encode proteins with predicted functions, and 3 correspond to tRNAs. Genes encoding two multisubunit RNA polymerases, chimallin and PhuZ, were identified, and AerS_266 was thus defined as a phiKZ-like phage. While similar phages with genomes >200 kb specific to Aeromonas hydrophila and Aeromonas veronii have been previously described, AerS_266 is the first phiKZ-like phage found to infect A. salmonicida.

Diversity and Current Classification of dsRNA Bacteriophages.

Half a century has passed since the discovery of Pseudomonas phage phi6, the first enveloped dsRNA bacteriophage to be isolated. It remained the sole known dsRNA phage for a quarter of a century and the only recognised member of the Cystoviridae family until the year 2018. After the initial discovery of phi6, additional dsRNA phages have been isolated from globally distant locations and identified in metatranscriptomic datasets, suggesting that this virus type is more ubiquitous in nature than previously acknowledged. Most identified dsRNA phages infect Pseudomonas strains and utilise either pilus or lipopolysaccharide components of the host as the primary receptor. In addition to the receptor-mediated strictly lytic lifestyle, an alternative persistent infection strategy has been described for some dsRNA phages. To date, complete genome sequences of fourteen dsRNA phage isolates are available. Despite the high sequence diversity, similar sets of genes can typically be found in the genomes of dsRNA phages, suggesting shared evolutionary trajectories. This review provides a brief overview of the recognised members of the Cystoviridae virus family and related dsRNA phage isolates, outlines the current classification of dsRNA phages, and discusses their relationships with eukaryotic RNA viruses.

Isolation, characterization, and genome analysis of novel bacteriophage – Stenotrophomonas phageCM1

A common environmental bacteria called Stenotrophomonas maltophilia has become an organism responsible for significant nosocomial infection, mortality in immunocompromised patients, and significantly increasing morbidity and is challenging to treat due to the antibiotic resistance activity of the organism. and bacteriophage therapy is one of the promising treatments against the organism. In this research, we isolated, identified, and characterized Stenotrophomonas phage CM1 against S. maltophilia. Stenotrophomonas phage CM1 head was measured to have a diameter of around 224.25 nm and a tail length of about 159 nm. The phage was found to have noticeable elongated tail spikes around 125 nm in length, the Myoviridae family of viruses, which is categorized under the order Caudovirales. The ideal pH for growth was around 7, demonstrated good thermal stability when incubated at 37–60 °C for 30 min or 60 min, and phage infectivity decreased marginally after 30 min of incubation at 1–5% chloroform concentration. Phage was 3,19,518 base pairs long and had an averaged G + C composition of 43.9 %; 559 open-reading frames (ORFs) were found in the bacteriophage genome, in which 508 of them are hypothetical proteins, 22 of them are other known proteins, 29 of them are tRNAs, and one of them is restriction enzyme. A phylogenetic tree was reconstructed, demonstrating that CM1 shares a close evolutionary relationship with other Stenotrophomonas phages.

The Isolation and Characterization of Bacteriophages Infecting Avian Pathogenic Escherichia coli O1, O2 and O78 Strains.

Avian pathogenic Escherichia coli (APEC), such as O1, O2 and O78, are important serogroups relating to chicken health, being responsible for colibacillosis. In this study, we isolated and characterized bacteriophages (phages) from hen feces and human sewage in Alberta with the potential for controlling colibacillosis in laying hens. The lytic profile, host range, pH tolerance and morphology of seven APEC-infecting phages (ASO1A, ASO1B, ASO2A, ASO78A, ASO2B, AVIO78A and ASO78B) were assessed using a microplate phage virulence assay and transmission electron microscopy (TEM). The potential safety of phages at the genome level was predicted using AMRFinderPlus and the Virulence Factor Database. Finally, phage genera and genetic relatedness with other known phages from the NCBI GenBank database were inferred using the virus intergenomic distance calculator and single gene-based phylogenetic trees. The seven APEC-infecting phages preferentially lysed APEC strains in this study, with ECL21443 (O2) being the most susceptible to phages (n = 5). ASO78A had the broadest host range, lysing all tested strains (n = 5) except ECL20885 (O1). Phages were viable at a pH of 2.5 or 3.5-9.0 after 4 h of incubation. Based on TEM, phages were classed as myovirus, siphovirus and podovirus. No genes associated with virulence, antimicrobial resistance or lysogeny were detected in phage genomes. Comparative genomic analysis placed six of the seven phages in five genera: Felixounavirus (ASO1A and ASO1B), Phapecoctavirus (ASO2A), Tequatrovirus (ASO78A), Kayfunavirus (ASO2B) and Sashavirus (AVIO78A). Based on the nucleotide intergenomic similarity (<70%), phage ASO78B was not assigned a genus in the siphovirus and could represent a new genus in class Caudoviricetes. The tail fiber protein phylogeny revealed variations within APEC-infecting phages and closely related phages. Diverse APEC-infecting phages harbored in the environment demonstrate the potential to control colibacillosis in poultry.

Isolation and Characterization of Bacteriophage against Drug-resistant Staphylococcus aureus

Staphylococcus aureus is one of the most successful pathogens due to its vast arsenal of virulence factors, including anchor proteins, secreted toxins and enzymes, polysaccharides, and immune system modulators. Bacteriophages are viruses that specifically target and infect bacterial cells. Bacteriophage is studied widely to improve the safety of foods and prevent food borne diseases of bacterial etiology, as well as to reduce the use of antibiotics in livestock. Besides, therapeutic applications of bacteriophage in human and the usage of phages in veterinary medicine and agriculture are also highly assessed. Hence, the present study aimed to isolate and to characterize Staphylococcus aureus specific bacteriophage. Bacteriophages were isolated from various environmental water samples. After incubation growth occurred in MSA and NA plate. On Staphylococcus aureus, antibiotic discs showed some useful identifying zones. It was performed with the use of five antibiotics: Penicillin, Oxacillin, Tetracyclin, Gentamycin and Cefoxitin. Penicillin, Oxacillin are showing no zones, for that reason showed resistant pattern. Environmental phages were then selected based on the size and clarity of their plaques. Bacteriophage produce some clear zone against bacteria. The isolated bacteriophages were found to be able to lyse the Staphylococcus aureus. S. aureus was isolated on nutrient agar media and mannitol salt agar media and confirmed by biochemical test like catalase test, coagulase test and oxidase test. Drug-resistant S. aureus also form some specific zones in the nutrient agar plates. Then allowed to compare this two specific zones stability.

Rare antibody phage isolation and discrimination (RAPID) biopanning enables identification of high-affinity antibodies against challenging targets

In vitro biopanning platforms using synthetic phage display antibody libraries have enabled the identification of antibodies against antigens that were once thought to be beyond the scope of immunization. Applying these methods against challenging targets remains a critical challenge. Here, we present a new biopanning pipeline, RAPID (Rare Antibody Phage Isolation and Discrimination), for the identification of rare high-affinity antibodies against challenging targets. RAPID biopanning uses fluorescent labeled phage displayed fragment antigen-binding (Fab) antibody libraries for the isolation of high-affinity binders with fluorescent activated sorting. Subsequently, discriminatory hit screening is performed with a biolayer interferometry (BLI) method, BIAS (Biolayer Interferometry Antibody Screen), where candidate binders are ranked and prioritized according to their estimated kinetic off rates. Previously reported antibodies were used to develop the methodology, and the RAPID biopanning pipeline was applied to three challenging targets (CHIP, Gαq, and CS3D), enabling the identification of high-affinity antibodies.

Phage Hunting in the High School Classroom: Phage Isolation and Characterization.

National science, technology, engineering, and mathematics education emphasizes science practices, such as hands-on learning. We describe a week-long activity where students participate in real-world scientific discovery, including "hunting" for bacteriophage in a variety of environmental samples. First, the students collect samples, then look for evidence of phage on "bait" bacteria, and finally amplify/purify the phages for further study.

Isolation and characterization of bacteriophages with activities against multi-drug-resistant Acinetobacter nosocomialis causing bloodstream infection invivo.

Acinetobacter nosocomialis (A. nosocomialis) is a glucose non-fermentative, gram-negative bacillus that belongs to the Acinetobacter calcoaceticus-baumannii complex. In recent years, studies have found an increased clinical prevalence of A. nosocomialis. However, given the increasing trend of antibiotic resistance, developing new antibacterial agents is vital. Currently, research regarding bacteriophage therapy against A. nosocomialis is only limited. Two A. nosocomialis bacteriophages, TCUAN1 and TCUAN2, were isolated from sewage. Experiments such as transmission electron microscopy (TEM), host-range analysis, and sequencing were performed to determine their biological and genomic characteristics. TCUAN2 were further subjected to invivo experiments and their derived-endolysin were cloned and tested against their bacteria host. Transmission electron microscopy revealed that TCUAN1 and TCUAN2 belong to Myoviridae and Podoviridae, respectively. Both phages show a broad host spectrum and rapid adsorption efficiency. Further biological analysis showed that TCUAN2 possesses a shorter latent period and larger burst size compared to TCUAN1. Because TCUAN2 showed a better antibacterial activity, it was injected into A. nosocomialis-infected mice which resulted in a significant decrease in bacterial load levels in the blood and increased the mice's survival. Finally, genomic analysis revealed that the complete nucleotide sequence of TCUAN1 is 49, 691 bps (containing 75 open reading frames) with a G+C content of 39.3%; whereas the complete nucleotide sequence of TCUAN2 is 41, 815 bps (containing 68 open reading frames) with a G+C content of 39.1%. The endolysin gene cloned and purified from TCUAN2 also showed antibacterial activity when used with a chelator EDTA.

SVep1, a temperate phage of human oral commensal Streptococcus vestibularis.

Bacteriophages play a vital role in the human oral microbiome, yet their precise impact on bacterial physiology and microbial communities remains relatively understudied due to the limited isolation and characterization of oral phages. To address this gap, the current study aimed to isolate and characterize novel oral phages. To achieve this, oral bacteria were isolated using a culture-omics method from 30 samples collected from healthy individuals. These bacteria were then cultured in three different types of media under both aerobic and anaerobic conditions. The samples were subsequently subjected to full-length 16S rRNA gene sequencing for analysis. Subsequently, we performed the isolation of lytic and lysogenic phages targeting all these bacteria. In the initial step, a total of 75 bacterial strains were successfully isolated, representing 30 species and 9 genera. Among these strains, Streptococcus was found to have the highest number of species. Using a full-length 16S rRNA gene similarity threshold of 98.65%, 14 potential novel bacterial species were identified. In the subsequent phase, a temperate phage, which specifically targets the human oral commensal bacterium S. vestibularis strain SVE8, was isolated. The genome of S. vestibularis SVE8 consists of a 1.96-megabase chromosome, along with a 43,492-base pair prophage designated as SVep1. Annotation of SVep1 revealed the presence of 62 open reading frames (ORFs), with the majority of them associated with phage functions. However, it is worth noting that no plaque formation was observed in S. vestibularis SVE8 following lytic induction using mitomycin C. Phage particles were successfully isolated from the supernatant of mitomycin C-treated cultures of S. vestibularis SVE8, and examination using transmission electron microscopy confirmed that SVep1 is a siphovirus. Notably, phylogenetic analysis suggested a common ancestral origin between phage SVep1 and the cos-type phages found in S. thermophilus. The presence of SVep1 may confer immunity to S. vestibularis against infection by related phages and holds potential for being engineered as a genetic tool to regulate oral microbiome homeostasis and oral diseases.

Isolation and characterization of bacteriophages Salmonella spp.

Against the background of reduced immunity of the body, the role of pathogenic and opportunistic microorganisms, which usually circulate in poultry farms in various associations, among the causative agents of poultry bacteriosis, is sharply increasing. Salmonella is one of the main bacteria affecting poultry and the most essential zoonotic pathogen causing foodborne illness. The work aimed to search and isolate lytic phages active in museum strains of Salmonella from the environment of poultry farms. The presence of lytic phages in museum strains of salmonella (Salmonella typhimurium 144 and Salmonella adobraco 1) was determined in the poultry houses samples according to Oliver and Grazia's standard method. It was established that the frequency of isolation of bacteriophages to the strain Salmonella typhimurium 144 from poultry farms was from 17.6 to 30.8 %, and the strain Salmonella adobraco 1 was 1.5 to 3.0 times less. In contrast, most often, lytic bacteriophages were isolated from sewage poultry houses. The size of negative colonies was larger in bacteriophages against Salmonella typhimurium 144 strain and was 2.8 ± 0.3 mm, which is 1.4 times larger, compared with colonies of bacteriophages lytic against Salmonella adobraco 1 strain. According to the degree of transparency, bacteriophages of Salmonella typhimurium 144 strain were primarily transparent. At the same time, the colonies of Salmonella adobraco 1 phages were translucent in most cases. Therefore, isolated bacteriophages for the Salmonella typhimurium 144 strain are better suited for developing a biological preparation for industrial poultry farming.

Macromonas nakdongensis sp. nov., Isolated from Freshwater and Characterization of Bacteriophage BK-30P-The First Phage That Infects Genus Macromonas.

A Gram-stain-negative, non-motile, non-pigmented, rod-shaped bacterium was isolated from a freshwater sample of Nakdong River in South Korea and designated as strain BK-30T. An analysis of the 16S rRNA gene sequence of strain BK-30T revealed its closest phylogenetic neighbors were members of the genus Macromonas. Specifically, the strain formed a robust clade with Macromonas bipunctata DSM 12705T, sharing 98.4% similarity in their 16S rRNA gene sequences. The average nucleotide identity value between strain BK-30T and M. bipunctata DSM 12705T was 79.8%, and the genome-to-genome distance averaged 21.3%, indicating the representation of a novel genomic species. Strain BK-30T exhibited optimum growth at 30 °C and pH 7.0, in the absence of NaCl. The major respiratory isoprenoid quinone identified was ubiquinone-8 (Q-8). The principal fatty acids detected were C16:1ω7c and/or C16:1ω6c (49.6%), C16:0 (27.5%), and C18:1ω7c and/or C18:1 ω6c (9.2%). The DNA G+C content of the strain was determined to be 67.3 mol%. Based on these data, we propose a novel species within the genus Macromonas, named Macromonas nakdongensis sp. nov., to accommodate the bacterial isolate. Strain BK-30T is designated as the type strain (=KCTC 52161T = JCM 31376T = FBCC-B1). Additionally, we present the isolation and complete genome sequence of a lytic phage infecting strain BK-30T, named BK-30P. This bacteriophage is the first reported to infect Macromonas, leading us to propose the name "Macromonasphage".

Isolation and Identification of a Sewage Pseudomonas aeruginosa-infecting Bacteriophage

Isolation and Identification of a Sewage Pseudomonas aeruginosa-infecting Bacteriophage

Isolation and Characterization of Lytic Bacteriophages against Aeromonas dhakensis Isolated from Water in Thailand

Phage therapy has emerged as a potential solution to the issue of multidrug-resistant bacteria. In this study, a novel bacteriophage vB_AdhS_M4 , which infects Aeromonas dhakensis, was isolated. A. dhakensis strains were isolated from water samples in Thailand and identified by biochemical and 16S rDNA sequence analysis. Four isolates, namely AM, NGP8, AK3, and SBKN4 were identified as A. dhakensis and used as hosts for phage isolation. Only 1 phage, vB_AdhS_M4, was obtained using A. dhakensis AM as host. Phage vB_AdhS_M4 morphology, host range, one-step growth curve, pH and temperature stability and genome were investigated. Transmission electron microscopy revealed that vB_AdhS_M4 has an icosahedral head of 64.8 ± 0.51 nm and a long tail of 185.4 ± 0.48 nm, suggesting that it belongs to the Siphoviridae family. Phage vB_AdhS_M4 had a latent period of 50 mins and a mean burst size of approximately 48 phage particles per infected cell. Our study on host-range determination demonstrated that this phage was specific for infecting A. dhakensis. Phage vB_AdhS_M4 was stable within a pH range of 4-7 and at temperatures ranging from 4 to 45 °C. The complete genome of Aeromonas phage vB_AdhS_M4 is 61,429 bp in length, with a G+C content of 61.7% and 77 open reading frames. In vitro A. dhakensis growth inhibition were observed with vB_AdhS_M4 at various MOIs. The greatest reduction in cell count occurred during the first 6-12 h of incubation with the phage, compared to the uninfected bacterial control, at all MOIs tested. Although the bacteria regrew after 24 h of incubation with the phage, the bacterial count remained lower than that of the control throughout the entire 48-h period. Based on these findings, it appears that vB_AdhS_M4 could be a valuable tool for biocontrol of A. dhakensis in aquaculture.

Characterization of Shiga toxin‐producing Escherichia coli bacteriophages isolated from agricultural environments and examination of their prevalence with bacterial hosts

AbstractIn the natural environment, ruminant livestock, including cattle, are the main reservoir of the outbreak–causing strains of Shiga toxin‐producing Escherichia coli (STEC), where bacteriophages sustainably thrive as well. This study focuses on the characterization of STEC‐specific bacteriophages isolated from cow manure samples in Maine farms and examines their prevalence with STEC hosts. Phenotypic features of representative isolates were characterized by using a transmission electron microscope. Similarly, host range, one‐step growth curve, thermal stability, lytic capability, and genomic analyses were performed to fully characterize selected representative isolates. Results showed that representative bacteriophage isolates belong to Myoviridae (S6P10 and S14P12) and Siphoviridae (S19). The most prevalent and common bacteriophages (46%) were specific to the O26 serogroup. The farm C sampling site had highly heterogenous bacteriophage populations that were specific to six STEC serogroups. The most prevalent bacteriophage isolate (S1P5, Escherichia phage vB_EcoM‐S1P5QW) was verified to have a double‐stranded DNA genome (166,102 bp) with 266 CDs of which 130 have known functions. The majority of the diverse bacteriophage isolates had strong lytic capabilities and a narrow host range that could withstand selected temperature conditions (−20, 37, and 62°C). Results of bacterial screening showed that STEC host strains were not detected in Farms A, C, and E, but were detected on Farms B and D. In conclusion, the highly‐diverse bacteriophage ecology found in cow manure samples may have been an important element in shaping the population of STEC serogroups, specifically in its natural environment, which can provide useful tools for potential antibiotic‐free therapeutics and diagnostic technologies.

Isolation and characterization of multidrug-resistant Salmonella-specific bacteriophages and their antibacterial efficiency in chicken breast

The use of phages as biocontrol agents against antibiotic-resistant strains of Salmonella spp. is gaining attention. This study aimed to isolate lytic bacteriophages specific for multidrug-resistant Salmonella enterica serovars Typhimurium; it also evaluated the bactericidal effect of isolated phages (STP-1, STP-2, STP-3, and STP-4) from sewage sample against S. Typhimurium as host strains. Moreover, a current study evaluated the efficacy of a bacteriophage cocktail against S. Typhimurium cocktail in chicken breast meat. The 4 phages were classified under the Caudoviricetes class by morphology characterization. On host range testing, they exhibited lytic activities against S. Typhimurium, S. Enteritidis, and S. Thompson. In the stability test, the phages exhibited resistance to heat (above 70°C for 1 h) and pH (strongly alkaline for 24 h). Additionally, the phages had comparable adsorption rates (approximately 80% adsorption in under 5 min). Additionally, the latent periods ranged from 30 to 50 min, with respective burst sizes of 31, 218, 197, and 218 PFU/CFU. In vitro, bacterial challenge demonstrated that at a multiplicity of infection (MOI) of 10, each phage consistently inhibited S. Typhimurium growth at 37°C for 24 h. In the food test, the phage cocktail (MOI=1,000) reduced S. Typhimurium in artificially contaminated chicken breast meat stored at 4°C by 0.9 and 1.2 log CFU/g after 1 and 7 d, respectively. The results point toward a promising avenue for addressing the challenge of multidrug-resistant S. Typhimurium in the food industry through the use of recently discovered phages. Notably, the exploration of phage cocktails holds significant potential for combating S. Typhimurium in chicken breast products in the times ahead.

Genomic diversity and biogeographic distributions of a novel lineage of bacteriophages that infect marine OM43 bacteria.

The marine methylotrophic OM43 clade is considered an important bacterial group in coastal microbial communities. OM43 bacteria, which are closely related to phytoplankton blooms, have small cell sizes and streamlined genomes. Bacteriophages profoundly shape the evolutionary trajectories, population dynamics, and physiology of microbes. The prevalence and diversity of several phages that infect OM43 bacteria have been reported. In this study, we isolated and sequenced two novel OM43 phages, MEP401 and MEP402. These phages share 90% of their open reading frames (ORFs) and are distinct from other known phage isolates. Furthermore, a total of 99 metagenomic viral genomes (MVGs) closely related to MEP401 and MEP402 were identified. Phylogenomic analyses suggest that MEP401, MEP402, and these identified MVGs belong to a novel subfamily in the family Zobellviridae and that they can be separated into two groups. Group I MVGs show conserved whole-genome synteny with MEP401, while group II MVGs possess the MEP401-type DNA replication module and a distinct type of morphogenesis and packaging module, suggesting that genomic recombination occurred between phages. Most members in these two groups were predicted to infect OM43 bacteria. Metagenomic read-mapping analysis revealed that the phages in these two groups are globally ubiquitous and display distinct biogeographic distributions, with some phages being predominant in cold regions, some exclusively detected in estuarine stations, and others displaying wider distributions. This study expands our knowledge of the diversity and ecology of a novel phage lineage that infects OM43 bacteria by describing their genomic diversity and global distribution patterns. IMPORTANCE OM43 phages that infect marine OM43 bacteria are important for host mortality, community structure, and physiological functions. In this study, two OM43 phages were isolated and characterized. Metagenomic viral genome (MVG) retrieval using these two OM43 phages as baits led to the identification of two phage groups of a new subfamily in the family Zobellviridae. We found that group I MVGs share similar genomic content and arrangement with MEP401 and MEP402, whereas group II MVGs only possess the MEP401-type DNA replication module. Metagenomic mapping analysis suggests that members in these two groups are globally ubiquitous with distinct distribution patterns. This study provides important insights into the genomic diversity and biogeography of the OM43 phages in the global ocean.

Bacteriophage Therapy to Control Bovine Mastitis: A Review.

Bovine mastitis is a polymicrobial disease characterised by inflammation of the udders of dairy and beef cattle. The infection has huge implications to health and welfare of animals, impacting milk and beef production and costing up to EUR 32 billion annually to the dairy industry, globally. Bacterial communities associated with the disease include representative species from Staphylococcus, Streptococcus, Enterococcus, Actinomyces, Aerococcus, Escherichia, Klebsiella and Proteus. Conventional treatment relies on antibiotics, but antimicrobial resistance, declining antibiotic innovations and biofilm production negatively impact therapeutic efficacy. Bacteriophages (phages) are viruses which effectively target and lyse bacteria with extreme specificity and can be a valuable supplement or replacement to antibiotics for bovine mastitis. In this review, we provide an overview of the etiology of bovine mastitis, the advantages of phage therapy over chemical antibiotics for the strains and research work conducted in the area in various model systems to support phage deployment in the dairy industry. We emphasise work on phage isolation procedures from samples obtained from mastitic and non-mastitic sources, characterisation and efficacy testing of single and multiple phages as standalone treatments or adjuncts to probiotics in various in vitro, ex vivo and in vivo bovine mastitis infection models. Furthermore, we highlight the areas where improvements can be made with focus on phage cocktail optimisation, formulation, and genetic engineering to improve delivery, stability, efficacy, and safety in cattle. Phage therapy is becoming more attractive in clinical medicine and agriculture and thus, could mitigate the impending catastrophe of antimicrobial resistance in the dairy sector.