Biological characteristics and genomic analysis of a Plesiomonas shigelloides phage phiP4-7

Abstract:

[Objective] The emergence of the multidrug resistant bacterial pathogens is posing great threats to food safety. Phages are the important bactericidal factors different from antibiotics. The evidence of phage application can be provided by analyzing the phage biological characteristics and genome. [Methods] In this study, one lytic phage phiP4-7 specific to the strain Plesiomonas shigelloides P4-7 was investigated on its biological characteristics, genome annotations, and taxonomic analysis. [Results] The images of transmission electron microscopy (TEM) showed that the phage has an icosahedral head with a diameter of (50.59±1.68) nm, a noncontractile tail with a length of (76.53±4.90) nm, belonging to the family of Siphoviridae. One-step growth curve suggested that phiP4-7 has a latent period of 25 min and its burst size was about 63 PFU/infection center. Additionally, phiP4-7 can effectively inhibit the growth of the host bacteria. The genome of phiP4-7 has been sequenced, assembled, and curated. It has a total of 39 825 bp with the GC content of 48.67%. Bioinformatic tools reveals that the phiP4-7 genome has 72 protein encoding genes, and no tRNA genes, antibiotic resistance genes, or virulence genes were identified. Comparative genomic and taxonomic analyses indicated that the genome of phiP4-7 showed little homology to any known viruses, and it can be classified as a member of a new genus of the Siphoviridae family. [Conclusion] A new Plesiomonas shigelloides phage was isolated, and its biological characteristics and genome were analyzed.