Isolation, whole genome sequencing and application of a broad-spectrum Salmonella phage.

Salmonella is considered as one of the most common zoonotic /foodborne pathogens in the world. The application of bacteriophages as novel antibacterial agents in food substrates has become an emerging strategy. Bacteriophages have the potential to control Salmonella contamination.We have isolated and characterized a broad-spectrum Salmonella phage, SP154, which can lyse 9 serotypes, including S. Enteritidis, S. Typhimurium, S. Pullorum, S. Arizonae, S. Dublin, S. Cholerasuis, S. Chester, S. 1, 4, [5], 12: i: -, and S. Derby, accounting for 81.9% of 144 isolates. SP154 showed a short latent period (40 min) and a high burst size (with the first rapid burst size at 107 PFUs/cell and the second rapid burst size at approximately 40 PFUs/cell). Furthermore, SP154 activity has higher survival rates across various environmental conditions, including pH 4.0-12.0 and temperatures ranging from 4 to 50 °C for 60 min, making it suitable for diverse food processing and storage applications. Significant reductions in live Salmonella were observed in different foods matrices such as milk and chicken meat, with a decrease of up to 1.9 log10 CFU/mL in milk contamination and a 1 log10 CFU/mL reduction in chicken meat. Whole genome sequencing analysis revealed that SP154 belongs to the genus Ithacavirus, subfamily Humphriesvirinae, within the family Schitoviridae. Phylogenetic analysis based on the terminase large subunit supported this classification, although an alternate tree using the tail spike protein gene suggested affiliation with the genus Kuttervirus, underscoring the limitations of relying on a single gene for phylogenetic inference. Importantly, no virulence or antibiotic resistance genes were detected in SP154. Our research highlights the potential of using SP154 for biocontrol of Salmonella in the food industry.

[An evaluation for the function and significance concerned to alterations of P16 3D structure with gene mutation in esophageal squamous cell carcinoma].

OBJECTIVE: To investigate the clinicopathologic significance of P16 3D structure alterations in human esophageal squamous cell carcinoma(ESCC) so as to open a new approach for the research on clinical prevention and treatment of ESCC. METHODS: All three techniques of polymerase chain reaction-single strand comformation polymorphism (PCR-SSCP), DNA sequencing and computerized three-dimensional protein-modeling were applied to analyze and determine the gene mutations and the computerized 3D changes of P16 protein molecule. RESULTS: The p16 gene abnormality were detected from thirty-three cases of sixty-nine ESCC, among which twenty-six cases of ESCC showed the alterations of amino acid residues located within the P16 functional domains (classified as group M2), but other seven cases displayed the amino acid changes happened to beyond the domains and far from the p16-CDK4/6 binding site (defined as group M1). The statistical analysis revealed that the significant differences in lymph node metastasis, distance metastasis and stage of clinical were found between M2 and M1 groups (P<0.05). However no significant difference in sex, age, invasion depth of tumor was observed (P>0.05). CONCLUSION: The mutations of p16 gene will alter the P16 protein structure. The four ankyrin repeats are the critical regions of P16 protein. The abnormalities in the ankyrin repeats will seriously alter the 3D structure and the activity of P16 protein, with resulting in lymph node metastasis, distance metastasis, and clinically advanced stage. The above results render an authentic criterion to the selection of the clinical cases with high risk of metastasis.