Dataset Information

Characterization of Salmonella Phage LPST153 That Effectively Targets Most Prevalent Salmonella Serovars.

ABSTRACT: Foodborne diseases represent a major risk to public health worldwide. In this study, LPST153, a novel Salmonella lytic phage with halo (indicative of potential depolymerase activity) was isolated by employing Salmonella enterica serovar Typhimurium ATCC 13311 as the host and had excellent lytic potential against Salmonella. LPST153 is effectively able to lyse most prevalent tested serotypes of Salmonella, including S. Typhimurium, S. Enteritidis, S. Pullorum and S. Gallinarum. Morphological analysis revealed that phage LPST153 belongs to Podoviridae family and Caudovirales order and could completely prevent host bacterial growth within 9 h at multiplicity of infection (MOI) of 0.1, 1, 10 and 100. LPST153 had a latent period of 10 min and a burst size of 113 ± 8 PFU/cell. Characterization of the phage LPST153 revealed that it would be active and stable in some harsh environments or in different conditions of food processing and storage. After genome sequencing and phylogenetic analysis, it is confirmed that LPST153 is a new member of the Teseptimavirus genus of Autographivirinae subfamily. Further application experiments showed that this phage has potential in controlling Salmonella in milk and sausage. LPST153 was also able to inhibit the formation of biofilms and it had the ability to reduce and kill bacteria from inside, including existing biofilms. Therefore, the phage LPST153 could be used as a potential antibacterial agent for Salmonella control in the food industry.

SUBMITTER: Islam MS

PROVIDER: S-EPMC7409278 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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Characterization of Salmonella Phage LPST153 That Effectively Targets Most Prevalent Salmonella Serovars.

Islam Md Sharifull MS Hu Yang Y Mizan Md Furkanur Rahaman MFR Yan Ting T Nime Ishatur I Zhou Yang Y Li Jinquan J

Microorganisms 20200721 7

Foodborne diseases represent a major risk to public health worldwide. In this study, LPST153, a novel Salmonella lytic phage with halo (indicative of potential depolymerase activity) was isolated by employing Salmonella enterica serovar Typhimurium ATCC 13311 as the host and had excellent lytic potential against Salmonella. LPST153 is effectively able to lyse most prevalent tested serotypes of Salmonella, including S. Typhimurium, S. Enteritidis, S.</ ...[more]

PMID: 32708328

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Project description:A total of 133 Salmonella isolates recovered from retail meats purchased in the United States and the People's Republic of China were assayed for antimicrobial susceptibility, the presence of integrons and antimicrobial resistance genes, and horizontal transfer of characterized antimicrobial resistance determinants via conjugation. Seventy-three (82%) of these Salmonella isolates were resistant to at least one antimicrobial agent. Resistance to the following antibiotics was common among the United States isolates: tetracycline (68% of the isolates were resistant), streptomycin (61%), sulfamethoxazole (42%), and ampicillin (29%). Eight Salmonella isolates (6%) were resistant to ceftriaxone. Fourteen isolates (11%) from the People's Republic of China were resistant to nalidixic acid and displayed decreased susceptibility to ciprofloxacin. A total of 19 different antimicrobial resistance genes were identified in 30 multidrug-resistant Salmonella isolates. The bla(CMY-2) gene, encoding a class A AmpC beta-lactamase, was detected in all 10 Salmonella isolates resistant to extended-spectrum beta-lactams. Resistance to ampicillin was most often associated with a TEM-1 family beta-lactamase gene. Six aminoglycoside resistance genes, aadA1, aadA2, aacC2, Kn, aph(3)-IIa, and aac(3)-IVa, were commonly present in the Salmonella isolates. Sixteen (54%) of 30 Salmonella isolates tested had integrons ranging in size from 0.75 to 2.7 kb. Conjugation studies demonstrated that there was plasmid-mediated transfer of genes encoding CMY-2 and TEM-1-like beta-lactamases. These data indicate that Salmonella isolates recovered from retail raw meats are commonly resistant to multiple antimicrobials, including those used for treating salmonellosis, such as ceftriaxone. Genes conferring antimicrobial resistance in Salmonella are often carried on integrons and plasmids and could be transmitted through conjugation. These mobile DNA elements have likely played an important role in transmission and dissemination of antimicrobial resistance determinants among Salmonella strains.

Project description:Foodborne diseases are a major challenge in the global food industry, especially those caused by multidrug-resistant (MDR) bacteria. Bacteria capable of biofilm formation, in addition to MDR strains, reduce the treatment efficacy, posing a significant threat to bacterial control. Bacteriophages, which are viruses that infect and kill bacteria, are considered a promising alternative in combating MDR bacteria, both in human medicine and animal production. Phage cocktails, comprising multiple phages, are commonly employed to broaden the host range and prevent or delay the development of phage resistance. There are numerous techniques and protocols available to evaluate the lytic activity of bacteriophages, with the most commonly used methods being Spot Test Assays, Efficiency of Plating (EOP), and infection assays in liquid culture. However, there is currently no standardization for which analyses should be employed and the possible differences among them in order to precisely determine the host range of phages and the composition of a cocktail. A preliminary selection using the Spot Test Assay resulted in four phages for subsequent evaluation against a panel of 36 Salmonella isolates of numerous serovars. Comparing EOP and infection assays in liquid culture revealed that EOP could underestimate the lytic activity of phages, directly influencing phage cocktail development. Moreover, the phage cocktail containing the four selected phages was able to control or remove biofilms formed by 66% (23/35) of the isolates, including those exhibiting low susceptibility to phages, according to EOP. Phages were characterized genomically, revealing the absence of genes associated with antibiotic resistance, virulence factors, or integrases. According to confocal laser scanning microscopy analysis, the biofilm maturation of one Salmonella isolate, which exhibited high susceptibility to phages in liquid culture and 96-well plates biofilm viability assays but had low values for EOP, was found to be inhibited and controlled by the phage cocktail. These observations indicate that phages could control and remove Salmonella biofilms throughout their growth and maturation process, despite their low EOP values. Moreover, using infection assays in liquid culture enables a more precise study of phage interactions for cocktail design timelessly and effortlessly. Hence, integrating strategies and techniques to comprehensively assess the host range and lytic activity of bacteriophages under different conditions can demonstrate more accurately the antibacterial potential of phage cocktails.

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Project description:BACKGROUND: Salmonella is a widely distributed foodborne pathogen that causes tens of millions of salmonellosis cases globally every year. While the genomic diversity of Salmonella is increasingly well studied, our knowledge of Salmonella phage genomic diversity is still rather limited, despite the contributions of both lysogenic and lytic phages to Salmonella virulence, diversity and ecology (e.g., through horizontal gene transfer and Salmonella lysis). To gain a better understanding of phage diversity in a specific ecological niche, we sequenced 22 Salmonella phages isolated from a number of dairy farms from New York State (United States) and analyzed them using a comparative genomics approach. RESULTS: Classification of the 22 phages according to the presence/absence of orthologous genes allowed for classification into 8 well supported clusters. In addition to two phage clusters that represent novel virulent Salmonella phages, we also identified four phage clusters that each contained previously characterized phages from multiple continents. Our analyses also identified two clusters of phages that carry putative virulence (e.g., adhesins) and antimicrobial resistance (tellurite and bicyclomycin) genes as well as virulent and temperate transducing phages. Insights into phage evolution from our analyses include (i) identification of DNA metabolism genes that may facilitate nucleotide synthesis in phages with a G+C % distinct from Salmonella, and (ii) evidence of Salmonella phage tailspike and fiber diversity due to both single nucleotide polymorphisms and major re-arrangements, which may affect the host specificity of Salmonella phages. CONCLUSIONS: Genomics-based characterization of 22 Salmonella phages isolated from dairy farms allowed for identification of a number of novel Salmonella phages. While the comparative genomics analyses of these phages provide a number of new insights in the evolution and diversity of Salmonella phages, they only represent a first glimpse into the diversity of Salmonella phages that is likely to be discovered when phages from different environments are characterized.

Dataset Information

Characterization of Salmonella Phage LPST153 That Effectively Targets Most Prevalent Salmonella Serovars.

Publications

Characterization of <i>Salmonella</i> Phage LPST153 That Effectively Targets Most Prevalent <i>Salmonella</i> Serovars.

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