Characterization of phiCFP‐1, a virulent bacteriophage specific for Citrobacter freundii

Abstract

Citrobacter freundii, a Gram-negative bacterium, causes many opportunistic infections. Bacteriophage phiCFP-1 was isolated and characterized by its ability to lyse the multidrug-resistant clinical C. freundii strain P10159. Transmission electron microscopy showed that the phage has an icosahedral head and a short tail, making it a Podoviridae family member. In a single-step growth experiment, phiCFP-1 exhibited an eclipse period of 20 min and a burst size of 100 particles per cell. Its genome assembled as a circular molecule when genomic sequencing was completed. However, based on genome content and organization, it was categorized as a classic T7-related phage, and such phages are known to have linear genomes with direct terminal repeats. With the quick and simple method established herein, the 38,625-bp linear double-stranded DNA with 229-bp direct terminal repeats was accurately identified. The genome contained 43 putative open reading frames and no tRNA genes. Using a proteomics-based approach, seven viral and two host proteins from purified phiCFP-1 particles were identified. Comparative genomics and recombination analyzes revealed close genetic relatedness among phiCFP-1, phiYeO3-12/vB_YenP_AP5 (from Yersinia enterocolitica O3), and phiSG-JL2 (from Salmonella enterica).

Isolation and characterization of a bacteriophage phiEap-2 infecting multidrug resistant Enterobacter aerogenes

“…Phage particles were resuspended in TM buffer (50 mM Tris-HCl [pH 7.8], 10 mM MgSO 4 ) and extracted with an equal volume of chloroform. After low-speed centrifugation (3,000 ×  g , 15 min, 4 °C), the aqueous phase was sedimented at about 25,000 ×  g for 60 min20.…”

Characterization and genome sequencing of a Citrobacter freundii phage CfP1 harboring a lysin active against multidrug-resistant isolates

“…To our knowledge, only two Podoviridae C. freundii-infecting phages (LK1 and phiCFP-1) were characterized so far (Chaudhry et al 2014;Zhao et al 2016). Recently, some myovirus genomes infecting C. freundii were also announced but without being microbiologically characterized.…”

“…Citrobacter phages remain understudied. To our knowledge, besides several Citrobacter phages have been sequenced (Edwards et al 2015;Hwang et al 2015;LeSage et al 2015), only three phages were characterized (Petty et al 2007;Chaudhry et al 2014;Zhao et al 2016). In fact, two Podoviridae C. freundii-infecting phages (LK1 and phiCFP-1) were partially characterized, being the third phage described as a transducing Podoviridae phage specific for Citrobacter rodentium.…”

DTDP-rhamnosyl transferase RfbF, is a newfound receptor-related regulatory protein for phage phiYe-F10 specific for Yersinia enterocolitica serotype O:3

“…The genomic comparisons indicated the phiYe-F10, PhiYeO3-12 and vB_YenP_AP5 were closely genetically related, and most of their DNA sequences appeared to have descended from a single common ancestral phage. The Podoviridae family phage was common in Enterobacteriaceae, which showed the morphologic characteristics of an icosahedral head and a short non-retractable tail when observed under transmission electron microscopy, and the phages were known to have double strands linear genomes with direct terminal repeats 39 40 . Currently, the reported Yersinia enterocolitica phage were belonged to different families, phage YeO3-12 and vB_YenP_AP5, which specific to infect Y. enterocolitica of serotype O:3 belonged to the family Podoviridae 12 14 ; however the temperate phage PY54 (GenBank accession no.…”