Characterization of a bacteriophage, vB_Eco4M-7, that effectively infects many Escherichia coli O157 strains

Abstract

The characterization of a recently isolated bacteriophage, vB_Eco4M-7, which effectively infects many, though not all, Escherichia coli O157 strains, is presented. The genome of this phage comprises doublestranded DNA, 68,084 bp in length, with a GC content of 46.2%. It contains 96 putative open reading frames (ORFs). Among them, the putative functions of only 35 ORFs were predicted (36.5%), whereas 61 ORFs (63.5%) were classified as hypothetical proteins. The genome of phage vB_Eco4M-7 does not contain genes coding for integrase, recombinase, repressors or excisionase, which are the main markers of temperate viruses. Therefore, we conclude that phage vB_Eco4M-7 should be considered a lytic virus. This was confirmed by monitoring phage lytic development by a one-step growth experiment. Moreover, the phage forms relatively small uniform plaques (1 mm diameter) with no properties of lysogenization. Electron microscopic analyses indicated that vB_Eco4M-7 belongs to the Myoviridae family. Based on mass spectrometric analyses, including the fragmentation pattern of unique peptides, 33 phage vB_Eco4M-7 proteins were assigned to annotated open reading frames. Importantly, genome analysis suggested that this E. coli phage is free of toxins and other virulence factors. In addition, a similar, previously reported but uncharacterized bacteriophage, ECML-117, was also investigated, and this phage exhibited properties similar to vB_Eco4M-7. Our results indicate that both studied phages are potential candidates for phage therapy and/or food protection against Shiga toxin-producing E. coli, as the majority of these strains belong to the O157 serotype.

Gida Kaynakli Patojen Escherichia Coli O157:h7’ye Karşi Etki̇li̇ Bakteri̇yofajlar

“…Ibrahim (1969) reported that E. coli phages were also effective against some Salmonella serovars. Liao et al (2019) (Necel et al, 2020). Chang and Kim (2011) Results from the present study are similar to these studies, revealing that some isolated phages are infective against E. coli O157:H7 strains with high target specificity and some isolated phages are infective against other E. coli strains and some Salmonella enterica serovars in addition to E. coli O157:H7 strains.…”

Characteristics of a Series of Three Bacteriophages Infecting Salmonella enterica Strains

“…The adsorption assay was performed according to the protocol described before [ 48 , 49 ], with some modifications. Adsorption rate of bacteriophages vB_SenM-1, vB_SenM-2, and vB_SenS-3 was analyzed at three different temperatures (25, 37, and 42 °C) and on four S. enterica strains: S. Typhimurium 12, S. Typhimurium 13, S. Enteritidis 64, and S. Enteritidis 1392 ( Table 1 ).…”

Characterization of the Bacteriophage vB_EfaS-271 Infecting Enterococcus faecalis

“…The incubation times of lysates with individual factors are listed in the Table 3 . Additionally, the stability of the phage particles was tested against five disinfectants used in the laboratory [ 80 ]. Each analysis was repeated three times.…”

“…DNA of vB_EfaS-271 was isolated from purified phage lysate according to a procedure described earlier [ 80 , 82 ]. The sample was treated with DNase I (1 U/µL; Thermo Fisher Scientific, Waltham, MA, USA) and RNaseA (5 µg/mL; Thermo Fisher Scientific) for 30 min at 37 °C to destroy bacterial nucleic acids.…”