Complete genome sequence of bacteriophage phiAS7, a T7-like virus that infects Aeromonas salmonicida subsp. salmonicida

To date, a number of Myoviridae bacteriophages that infect Aeromonadaceae have been identified and characterized. However, the genome sequences of Aeromonas phages that not belong to the Myoviridae have not been investigated yet. Herein, we report the complete genome sequence of Aeromonas phage phiAS7, which belongs to the Podoviridae and infects Aeromonas salmonicida subsp. salmonicida.     

Characterization and complete genome sequence of vB_EcoP-Bp4,a novel polyvalent N4-like bacteriophage that infects chicken pathogenic Escherichia coli

正Dear Editor,Pathogenic Escherichia coli cause chicken colibacillosis,which is economically devastating to the poultry industry worldwide(Bagheri et al.,2014).Owing to increasing antibiotic resistance,phage therapy reagents have been developed to treat bacterial infections(Xu et al.,2015).Coliphage N4 is the first reported phage in theN4-like virusesgenus and the only member recognized by     

Swimming marine Synechococcus strains with widely different photosynthetic pigment ratios form a monophyletic group

Unicellular marine cyanobacteria are ubiquitous in both coastal and oligotrophic regimes. The contribution of these organisms to primary production and nutrient cycling is substantial on a global scale. Natural populations of marine Synechococcus strains include multiple genetic lineages, but the link, if any, between unique phenotypic traits and specific genetic groups is still not understood. We studied the genetic diversity (as determined by the DNA-dependent RNA polymerase rpoC1 gene sequence) of a set of marine Synechococcus isolates that are able to swim. Our results show that these isolates form a monophyletic group. This finding represents the first example of correspondence between a physiological trait and a phylogenetic group in marine Synechococcus. In contrast, the phycourobilin (PUB)/phycoerythrobilin (PEB) pigment ratios of members of the motile clade varied considerably. An isolate obtained from the California Current (strain CC9703) displayed a pigment signature identical to that of nonmotile strain WH7803, which is considered a model for low-PUB/PEB-ratio strains, whereas several motile strains had higher PUB/PEB ratios than strain WH8103, which is considered a model for high-PUB/PEB-ratio strains. These findings indicate that the PUB/PEB pigment ratio is not a useful characteristic for defining phylogenetic groups of marine Synechococcus strains.     

A restriction map of the bacteriophage T4 genome

Summary We report a detailed restriction map of the bacteriophage T4 genome and the alignment of this map with the genetic map. The sites cut by the enzymes BglII, XhoI, KpnI, SalI, PstI, EcoRI and HindIII have been localized. Several novel approaches including two-dimensional (double restriction) electrophoretic separations were used.     

Characterization and complete genome sequence of vB_EcoP-Bp4, a novel polyvalent N4-like bacteriophage that infects chicken pathogenic <Emphasis Type="Italic">Escherichia coli</Emphasis>

Electronic Supplementary MaterialSupplementary material is available for this article at 10.1007/s12250-016-3787-4 and is accessible for authorized users.     

The genome of bacteriophage K1F, a T7-like phage that has acquired the ability to replicate on K1 strains of Escherichia coli

Bacteriophage K1F specifically infects Escherichia coli strains that produce the K1 polysaccharide capsule. Like several other K1 capsule-specific phages, K1F encodes an endo-neuraminidase (endosialidase) that is part of the tail structure which allows the phage to recognize and degrade the polysaccharide capsule. The complete nucleotide sequence of the K1F genome reveals that it is closely related to bacteriophage T7 in both genome organization and sequence similarity. The most striking difference between the two phages is that K1F encodes the endosialidase in the analogous position to the T7 tail fiber gene. This is in contrast with bacteriophage K1-5, another K1-specific phage, which encodes a very similar endosialidase which is part of a tail gene "module" at the end of the phage genome. It appears that diverse phages have acquired endosialidase genes by horizontal gene transfer and that these genes or gene products have adapted to different genome and virion architectures.     

Genomic and biological characterization of vB_PvuS_Pm34, a novel lytic bacteriophage that infects Proteus vulgaris

Proteus phage vB_PvuS_Pm34 (Pm34) isolated from the sewage, is a novel virus specific to Proteus vulgaris. Pm34 belonged to the family Siphovirodae with an icosahedron capsid head and a non-contractile tail. Its genome was 39,558 bp in length with a G + C content of 41.4%. Similarity analysis showed that Pm34 shared low identities of 27.6%–38.4% with any other Proteus phages, but had the 96% high identity with Proteus mirabilis AOUC-001. In the genome of Pm34, 70 open reading frames was deduced and 32 had putative functions including integrase and host lysis proteins. No tRNAs, antibiotic resistance and virulence genes were detected. Pm 34 presented a broad pH (4–8) and good temperature tolerance (<40 °C). This is the first report of the bacteriophage specific to P. vulgaris, which can enrich the knowledge of bacteriophages of Prouteus bacteria and provide the possibility for the alternative treatment of P. vulgaris infection.     

The genome of lipid-containing bacteriophage PRD1, which infects gram-negative bacteria, contains long, inverted terminal repeats.

The bacteriophage PRD1 is a lipid-bearing phage that infects a wide variety of gram-negative bacteria, including Escherichia coli and Salmonella typhimurium when they contain the appropriate plasmid. It contains a linear duplex DNA molecule that is covalently bound by its 5' ends to a terminal protein. We report here that the PRD1 genome contains a 111-base-pair terminal inverted repeat which does not bear homology to that of any known linear duplex DNAs with terminal proteins. We further report that its 3' termini are susceptible to enzymatic digestion by exonuclease III.     

The isolation and characterization of bacterial strains (Tab32) that restrict bacteriophage T4 gene 32 mutants

Summary Gene 32 of bacteriophage T4 codes for a single-stranded DNA binding protein. We have isolated mutants of Escherichia coli (called Tab32) that specifically restrict the growth of gene 32 missense mutants and allow normal growth of T4⁺. During infections of Tab32 with 32^tsL171, large amounts of DNA are synthesized and late proteins are made, but very few progeny phage are produced. At least two bacterial mutations are necessary for the restrictive phenotype; these mutations have been mapped to about min 41 and min 64.     

Evidence that bacteriophage T4 eph1 is a missense hoc mutation

An electrophoretic mutation of bacteriophage T4, eph1, appears to code for a missense hoc (highly antigenic outer capsid) protein. This is based on the observation that particles lacking hoc protein (hoc- particles), after incubation in a crude extract of Escherichia coli infected with phage carrying the eph1 mutation acquired the electrophoretic mobility of the eph1 strain (the electrophoretic mobility of the eph1 strain itself is slower than that of hoc- particles). Thus, it is likely that during infection of E. coli with the eph1 strain, a hoc protein is made that has a lower negative charge than normal hoc protein but can nevertheless bind to particles lacking hoc protein. These results confirm that eph1 is a hoc mutation.     

Mutants of bacteriophage T4 that produce infective fibreless particles

In wild type bacteriophage T4 the long tail fibres serve both in the initial attachment of the phage to its host and in the triggering of tail contraction. A two-step model for the control of triggering suggests that particles lacking the product of gene 9, which are also structurally fibreless, might be infective. This is shown to be the case, even though such phage do not plate on restrictive strains of bacteria. However, starting from phage carrying an amber mutation in gene 9 it is easy to isolate additional mutations which, under restrictive conditions, permit fibreless plating (pfp mutations). Three such pfp mutations, having also a temperature-sensitive phenotype, have been isolated and shown to map in genes coding for structural components of the baseplate. The mode of action of these pfp mutations is not clear, though they certainly destabilize the baseplate, thereby making triggering easier. The pfp mutations are effective only when in combination with an amber mutation in gene 9 and not with amber mutations in tail fibre genes, establishing the essentially inhibitory nature of the control of triggering exercised by gene 9 product.