Phenotypic characterization and genome analysis of a novel Salmonella Typhimurium phage having unique tail fiber genes

Abstract

Salmonella enterica serovar Typhimurium is a foodborne pathogen causing occasional outbreaks of enteric infections in humans. Salmonella has one of the largest pools of temperate phages in its genome that possess evolutionary significance for pathogen. In this study, we characterized a novel temperate phage Salmonella phage BIS20 (BIS20) with unique tail fiber genes. It belongs to the subfamily Peduovirinae genus Eganvirus and infects Salmonella Typhimurium strain (SE-BS17; Acc. NO MZ503545) of poultry origin. Phage BIS20 was viable only at biological pH and temperature ranges (pH7 and 37 °C). Despite being temperate BIS20 significantly slowed down the growth of host strain for 24 h as compared to control (P < 0.009). Phage BIS20 features 29,477-base pair (bp) linear DNA genome with 53% GC content and encodes for 37 putative ORFs. These ORFs have mosaic arrangement as indicated by its ORF similarity to various phages and prophages in NCBI. Genome analysis indicates its similarity to Salmonella enterica serovar Senftenberg prophage (SEStP) sequence (Nucleotide similarity 87.7%) and Escherichia virus 186 (~ 82.4% nucleotide similarity). Capsid genes were conserved however those associated with tail fiber formation and assembly were unique to all members of genus Eganvirus. We found strong evidence of recombination hotspot in tail fiber gene. Our study identifies BIS20 as a new species of genus Eganvirus temperate phages as its maximum nucleotide similarity is 82.4% with any phage in NCBI. Our findings may contribute to understanding of origin of new temperate phages.

Newly Isolated Virulent Salmophages for Biocontrol of Multidrug-Resistant Salmonella in Ready-to-Eat Plant-Based Food

“…The highest titer of salmophage BIS20 was observed at pH 7, whereas a significant reduction in titer was observed at pH 9 after 1 h of incubation. No plaque zones were observed at pH 2, 5, and 12 [ 72 ]. The pH stability test of the salmophage LPST153 showed that it was highly stable with pH ranging from 4 to 12.…”

Genetic characteristics and integration specificity of Salmonella enterica temperate phages

“…Salmonella enterica has been traditionally classified to different serotypes (serovars) and was reported that >2,500 serotypes cause most human infections ( Jackson et al, 2013 ). Many researches focus on identifying and characterizing the temperate phages for specific S. enterica serotypes, such as phage mTmV in S. enterica serotype Typhimurium ( S. typhimurium ) ST34 ( Tassinari et al, 2020 ), phage BIS20 in S. typhimurium ( Sattar et al, 2022 ), phage ZCSE9 in S. typhimurium ( Abdelsattar et al, 2023 ), phage SGP-C in S. enterica serotype gallinarum biovar gallinarum ( S. gallinarum ; Ilyas et al, 2022 ), phages vB_SenM-1, vB_SenM-2, vB_SenS-3 in 20 S. enterica serotypes, including S. heidelberg , S. panama , S. typhimurium , S. cholerasuis , S. enteritidis , S. virchow , etc. ( Kosznik-Kwasnicka et al, 2020 ).…”

Genomic Features and Phylogenetic Analysis of Antimicrobial-Resistant Salmonella Mbandaka ST413 Strains

“…Typhimurium, integrates near tRNAs and was found to be associated with tRNA-Arg (anticodon CCT) in our study with S. Mbandaka, facilitating pathogenicity islands integration, which can affect gene expression and modulate virulence [ 72 ]. While temperate phages like SW9 and phiV10 are related to aid Salmonella adaptation during infection [ 73 ], further investigation is needed on phiV10 integration in the Salmonella genus, given its specific association with E. coli O157:H7 [ 74 ], which is associated with severe intestinal infections [ 75 ]. Despite the diversity of phages described in this study, no genes encoding virulence or antibiotic resistance were predicted in the 10 phage sequences; however, our understanding of the ecology and diversity of S. Mbandaka phages is limited, and it is imperative to conduct additional tests to confirm the absence of these genes.…”