Complete genome sequence of enterobacteria phage 4MG, a new member of the subgroup "PVP-SE1-like phage" of the "rV5-like viruses"

Isolation and characterization of Hena1 - a novel Erwinia amylovora bacteriophage

Fire blight, caused by plant pathogenic bacterium Erwinia amylovora, is one of the most important diseases of Rosaceae plants. Due to the lack of effective control measures, fire blight infections pose a recurrent threat on agricultural production worldwide. Recently, bacterial viruses, or bacteriophages, have been proposed as environmentally friendly natural antimicrobial agents for fire blight control. Here, we isolated a novel bacteriophage Hena1 with activity against E. amylovora. Further analysis revealed that Hena1 is a narrow-host-range lytic phage belonging to Myoviridae family. Its genome consists of a linear 148,842 bp dsDNA (48.42% GC content) encoding 240 ORFs and 23 tRNA genes. Based on virion structure and genomic composition, Hena1 was classified as a new species of bacteriophage subfamily Vequintavirinae. The comprehensive analysis of Hena1 genome may provide further insights into evolution of bacteriophages infecting plant pathogenic bacteria.

Characterization of Endolysin LysECP26 Derived from rV5-like Phage vB_EcoM-ECP26 for Inactivation of Escherichia coli O157:H7

With an increase in the consumption of non-heated fresh food, foodborne shiga toxin-producing Escherichia coli (STEC) has emerged as one of the most problematic pathogens worldwide. Endolysin, a bacteriophage-derived lysis protein, is able to lyse the target bacteria without any special resistance, and thus has been garnering interest as a powerful antimicrobial agent. In this study, rV5-like phage endolysin targeting E. coli O157:H7, named as LysECP26, was identified and purified. This endolysin had a lysozyme-like catalytic domain, but differed markedly from the sequence of lambda phage endolysin. LysECP26 exhibited strong activity with a broad lytic spectrum against various gram-negative strains (29/29) and was relatively stable at a broad temperature range (4°C- 55°C). The optimum temperature and pH ranges of LysECP26 were identified at 37°C-42°C and pH 7- 8, respectively. NaCl supplementation did not affect the lytic activity. Although LysECP26 was limited in that it could not pass the outer membrane, E. coli O157: H7 could be effectively controlled by adding ethylenediaminetetraacetic acid (EDTA) and citric acid (1.44 and 1.14 log CFU/ml) within 30 min. Therefore, LysECP26 may serv as an effective biocontrol agent for gram-negative pathogens, including E. coli O157:H7.

Complete genome sequence of C130_2, a novel myovirus infecting pathogenic Escherichia coli and Shigella strains

The genome sequence of a novel virulent bacteriophage, named " C130_2", that is morphologically a member of the family Myoviridae is reported. The 41,775-base-pair double-stranded DNA genome of C130_2 contains 59 ORFs but exhibits overall low sequence similarity to bacteriophage genomes for which sequences are publicly available. Phylogenetic analysis indicated that C130_2 represents a new phage type. C130_2 could be propagated well on enterohemorrhagic Escherichia coli (EHEC) O157:H7 and other pathogenic E. coli strains, as well as on strains of various Shigella species.

Different Ancestries of R Tailocins in Rhizospheric Pseudomonas Isolates

Bacterial genomes accommodate a variety of mobile genetic elements, including bacteriophage-related clusters that encode phage tail-like protein complexes playing a role in interactions with eukaryotic or prokaryotic cells. Such tailocins are unable to replicate inside target cells due to the lack of a phage head with associated DNA. A subset of tailocins mediate antagonistic activities with bacteriocin-like specificity. Functional characterization of bactericidal tailocins of two Pseudomonas putida rhizosphere isolates revealed not only extensive similarity with the tail assembly module of the Pseudomonas aeruginosa R-type pyocins but also differences in genomic integration site, regulatory genes, and lytic release modules. Conversely, these three features are quite similar between strains of the P. putida and Pseudomonas fluorescens clades, although phylogenetic analysis of tail genes suggests them to have evolved separately. Unlike P. aeruginosa R pyocin elements, the tailocin gene clusters of other pseudomonads frequently carry cargo genes, including bacteriocins. Compared with P. aeruginosa, the tailocin tail fiber sequences that act as specificity determinants have diverged much more extensively among the other pseudomonad species, mostly isolates from soil and plant environments. Activity of the P. putida antibacterial particles requires a functional lipopolysaccharide layer on target cells, but contrary to R pyocins from P. aeruginosa, strain susceptibilities surpass species boundaries.

Complete Genome Sequences of Two Escherichia coli O157:H7 Phages Effective in Limiting Contamination of Food Products

We previously demonstrated that application of bacteriophages significantly reduced Escherichia coli O157:H7 contamination in spinach and ground beef. Here, we present the genomic sequences of two bacteriophages, vB_EcoS_FFH_1, a T5-like phage, and vB_EcoM_FFH_2, an rV5-like phage, used in those treatments.