Shipin Kexue (Jan 2024)
Characteristic Analysis of Salmonella Phage Pu29 and Its Application in Magnetic Separation and Enrichment of Salmonella
Abstract
Salmonella pullorum phage Pu29 was comprehensively analyzed for its biological and genomic characteristics. A magnetic separation and enrichment technique for Salmonella was established using the phage Pu29 as a recognition element. The phage belonged to the genus Roufvirus and had an icosahedron head and an irreducible long tail. Pu29 had a wide host spectrum with an adsorption rate of 88.67% on host cells in 15 min, a latent period of 30 min, a rise period of 180 min, and a burst size of 115.74 PFU/cell. Meanwhile, Pu29 had good heat resistance (30–60 ℃) and pH tolerance (pH 4–11). Its genome was composed of 45 715 bp (GC content 46.08%) and 81 open reading frames (ORFs), including 18 ORFs with known functions that did not carry genes encoding toxicity or resistance factors. PhagePu29-MBs were prepared as a probe by coupling the phage with carboxylated nano-magnetic beads (MBs) through amide reaction. When 25 μg of the probe was incubated with Salmonella at 37 ℃ for 20 min, the highest capture rate of Salmonella of 83.93% and the lowest captured bacterial concentration of 45 CFU/mL were obtained. Transmission electron microscopy (TEM) was used to observe that PhagePu29-MBs could specifically capture Salmonella. In spiked samples, the highest capture rate of Salmonella separated and enriched by the probe reached 92.92%. The separation and enrichment process took approximately 30 min. Therefore, this study established a fast and highly specific magnetic separation method for Salmonella based on phage Pu29, which may lay the foundation for the development of a phage-based method for the rapid separation and enrichment of foodborne pathogens in food samples.
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